Researcher Profile and Settings

Affiliation

• Institute of Low Temperature Science　Frontier Ice and Snow Science

Job Title

• Professor

Degree

• Doctor of Engineering（Osaka City University）
• Master of Engineering（Osaka City University）
• Bachelor of Engineering（Osaka City University）

URL

http://www.lowtem.hokudai.ac.jp/ptdice/index.html

Research funding number

• 60261509

J-Global ID

• 200901076078296911

Research Interests

• crystal growth, ice, protein, development of advanced optical microscopy   Crystal Growth   

Research Areas

• Natural sciences / Bio-, chemical, and soft-matter physics
• Nanotechnology/Materials / Thin-film surfaces and interfaces
• Nanotechnology/Materials / Crystal engineering
• Nanotechnology/Materials / Applied materials

Educational Organization

•  Master's degree program　Graduate School of Science
•  Doctoral (PhD) degree program　Graduate School of Science

Academic & Professional Experience

• 2014/07 - 2014/09 Chinese Academy of Science National Microgravity Laboratory, Institute of Mechanics Visiting Professor
• 2007/08 - 2014/03 - Specially Appointed Professor,Dept. Electrical, Electronic and Information Engineering, Graduate School of Engineering, Osaka University
• 2007 - 2014/03 - 大阪大学大学院工学研究科電気電子情報工学専攻 特任教授
• 2008 - 2012 科学技術振興機構さきがけ研究者 さきがけ研究者
• 2008 - 2012 Hokkaido University Institute of Low Temperature Science
• 2008 - 2012 Researcher on Precursory Research for Embryonic Science and Technology (PRESTO),Japan Science and Technology Agency
• 2012 - 北海道大学低温科学研究所 教授
• 2012 - Professor,Institute of Low Temperature Science, Hokkaido University
• 2007 - 2008 スペイン科学研究高等評議会，アンダルシア地球科学研究所，結晶学研究室 契約研究者
• 2007 - 2008 Investigado Contrato,Laboratorio de Estudios Cristalograficos, Instituto Andaluz de Ciencias de la Tierra, Consejo Superior de Investigaciones Cientificas
• 2001 - 2007 Tohoku University Institute for Materials Research
• 2001 - 2007 Lecturer,Institute for Materials Research, Tohoku University
• 2004 - 2006 Tohoku University Center for Interdisciplinary Research
• 2004 - 2006 Project Leader,Center for Interdisciplinary Research, Tohoku University
• 2001 - 2004 Tohoku University Center for Interdisciplinary Research
• 2001 - 2004 Program Leader,Center for Interdisciplinary Research, Tohoku University
• 1994 - 2001 Tohoku University Institute for Materials Research
• 1994 - 2001 Research Associate,Institute for Materials Research, Tohoku University

Education

•        - 1994  Osaka City University
•        - 1994  Osaka City University  Graduate School, Division of Engineering  Department of Applied Chemistry
•        - 1991  Osaka City University
•        - 1991  Osaka City University  Graduate School, Division of Engineering
•        - 1989  Osaka City University  Faculty of Engineering
•        - 1989  Osaka City University  Faculty of Engineering  Department of Applied Chemistry

Association Memberships

• 応用物理学会   日本マイクログラビティ応用学会   日本物理学会   日本結晶成長学会   The Japan Society of Applied Physics   The Japan Society of Microgravity Application   The Physical Society of Japan   Japanese Association of Crystal Growth   

Research Activities

Published Papers

• The emergence of drop-type and thin-layer-type quasi-liquid layers on ice crystal surfaces and their thermodynamic origin

  Gen Sazaki, Ken ichiro Murata, Harutoshi Asakawa, Ken Nagashima, Shunichi Nakatsubo, Yoshinori Furukawa

  Journal of Crystal Growth 597 0022-0248 2022/11/01 

  Ice crystals play crucially important roles in wide variety of natural phenomena on the earth's surface. However, in-situ optical observation of quasi-liquid layers (QLLs), which governs properties of ice crystal surfaces at temperature close to 0 °C, has been an experimental challenge. In this review, we show our recent studies on the in-situ observation of QLLs formed by the surface melting of ice crystals at temperatures below 0 °C. We first show our advanced optical microscopy that can directly visualize individual elementary steps (0.4 nm in thickness) on ice crystal surfaces. Then we next demonstrate the emergence of two kinds of QLLs with different morphologies (droplets and thin layers) on basal and prism faces of ice crystals. We also determined the surface tension-to-shear viscosity ratio (the so-called characteristic velocity) of both QLLs, indicating that the drop-type and thin-layer-type QLLs are 20- and 200-times less fluidic than bulk water, respectively. In addition, we measured the contact angles of drop-type QLLs on ice crystal surfaces and found that the formation of the drop-type and thin-layer-type QLLs can be explained by the wetting transition of QLLs on ice crystal surfaces. Furthermore, we determined the water vapor pressure–temperature ranges, in which both QLLs can present, and found that both QLLs are formed kinetically only in supersaturated or undersaturated water vapor. Our findings show a novel picture of surface melting that were significantly different from the conventional picture in which one QLL phase appear uniformly on ice crystal surfaces.
• Growth Kinetics of Elementary Spiral Steps on Ice Prism Faces Grown in Vapor and Their Temperature Dependence

  Genki Miyamoto, Akira Kouchi, Ken-ichiro Murata, Ken Nagashima, Gen Sazaki

  CRYSTAL GROWTH & DESIGN 1528-7483 2022/10 

  We grew prism faces of ice crystals heteroepitaxially on a {10 (1) over bar0} CdSe wafer. Then, we observed the lateral growth of elementary spiral steps on prism faces in vapor by advanced optical microscopy. On prism faces, we found that outcrops of screw dislocations are mostly located in the interiors of prism faces and that distance L between adjacent spiral steps is uniform, whereas these two features are not observed on basal faces. We measured the velocity Vstep of elementary spiral steps on prism faces under various supersaturation and determined the step kinetic coefficient beta. Then, we revealed that the value of fi on prism faces monotonically decreases with decreasing temperature (T) from -2.6 to -25.0 degrees C. In this T range, the value of beta on prism faces is significantly smaller than that on basal faces (determined previously). We further analyzed the relation between L and driving force for crystallization Delta mu and found that at T similar to -15 degrees C, the step ledge free energy kappa on prism faces reaches a peak (8.5 x 10(-10) J/m), implying the change in surface structures at this temperature.
• Step-bunching instability of growing interfaces between ice and supercooled water

  Ken-ichiro Murata, Masahide Sato, Makio Uwaha, Fumiaki Saito, Ken Nagashima, Gen Sazaki

  Proceedings of the National Academy of Sciences 119 (10) 0027-8424 2022/03/08 [Refereed][Not invited]
   

  Ice-crystal growth in supercooled water is one of the most familiar examples of phase-transition dynamics, playing essential roles in various natural phenomena on Earth. Despite its fundamental importance, the microscopic view at the elementary step level remains elusive. Here, using an advanced optical microscope, we find self-organization of elementary steps during ice-crystal growth, called step-bunching instability (SBI), driven by the competition between step dynamics, interfacial stiffness, and latent heat diffusions. We also find that the SBI transiently induces screw dislocations and resulting spiral growth in the late stage of the growth process. Furthermore, quantitative observations with a two-beam interferometer allow us to obtain insights into the relative importance of the various mechanisms of the step-step interactions. Our finding offers a significant clue to understanding the general mechanism of melt growth beyond ice-crystal growth, inseparably involving several broad research fields, including cryobiological, geophysical, and material branches.
• Cuticular Lipid Topology on Insect Body Surfaces Studied by Synchrotron Radiation FTIR ATR Microspectroscopy

  Fumitoshi Kaneko, Chihiro Katagiri, Ken Nagashima, Gen Sazaki, Yuka Ikemoto

  JOURNAL OF PHYSICAL CHEMISTRY B 125 (34) 9757 - 9767 1520-6106 2021/09 [Refereed]
   

  The cuticular lipid covering the integument of insects is exposed to the environment and involved in a variety of functions offered by insect body surfaces, ranging from protection against the environment, such as the control of water transpiration, the reduction of abrasive damage, and the prevention of pathogen intrusion, to the communication between insects from intraspecific to interspecific interactions. In comparison with the importance of their physiological functions, there is remarkably little information on the structure and physical property of cuticular lipids on insect body surfaces. The lipid layer on the outer exoskeleton is very thin, estimated on the order of 0.01-1 mu m or less, and this has led to a lack of practical methodologies for detailed structural analyses. To fill this devoid, we have exploited the characteristics of Fourier transform infrared (FTIR) attenuated total reflection (ATR) spectroscopy, which allows us to conduct a chemical analysis on insect body surfaces and also to investigate depth-dependent structural changes. We have applied a combination of FTIR ATR microspectroscopy with IR radiation provided by a synchrotron facility to obtain in situ two-dimensional (2D) information of the cuticular lipid layer on the surface of the integument. The 2D FTIR spectra measured on the two-spotted cricket and the American cockroach show that the IR bands due to the cuticular lipid, such as CH2 symmetric and antisymmetric stretch, nu(a)(CH2) and nu(s)(CH2), change in intensity significantly, depending on the location of measurements. As if to keep pace with this, the bands of the amide group for the underlying cuticular layer also change in intensity significantly, although the changes are in the opposite direction; as the lipid bands increase in intensity, the amide band decreases, and vice versa. The ATR spectral analysis, which takes into account the characteristics of the evanescent wave, points out that the lipid layer would vary tens of times in the range of 0.01-1 mu m significantly. The nu(a)(CH2) and nu(s)(CH2) bands show frequency shifts, which correlate to some extent with their intensity changes, suggesting that the drastic uneven distribution of the cuticular lipid would be related to the solid-liquid phase separation and also the coarsening of the solid phase domains. The formation of such topological features, significant heterogeneity in the lipid layer thickness, and solid-liquid phase ratios would be accompanied by the partitioning of lipid components according to molecular structures and physicochemical properties. Considering that each lipid component in insect body surface lipids is involved in various physiological roles, the segregation of lipid components during the formation of such heterogeneous structures is thought to have a significant impact on the functionality of the insect body surface.
• HCl Droplets Induced Bunched Steps on Ice Crystal Surfaces under Atmospheric-Concentration HCl Gas

  Ken Nagashima, Ken-ichiro Murata, Gen Sazaki

  CRYSTAL GROWTH & DESIGN 21 (4) 2508 - 2515 1528-7483 2021/04 [Refereed]
   

  Surfaces of ice act as sites of various chemical reactions of atmospheric acidic gases, which cause serious environmental issues, such as the catalytic ozone depletion by hydrogen chloride (HCl) gas. Here, we show direct observations of ice basal faces by advanced optical microscopy under atmospheric-concentration HCl gases of 10(-4) and 10(-2) Pa. We found that liquid droplets and thin layers appeared/disappeared on the ice basal faces at about -1 degrees C with increasing/decreasing temperatures. These behaviors were similar to those in the absence of the HCl gases. In contrast, at temperatures below -10 degrees C, surprisingly we found that with decreasing temperature the HCl gases induced the appearance of droplets of an HCl aqueous solution on the basal faces. In addition, the HCl droplets pinned the lateral advancement of spiral steps, resulting in the formation of bunched steps. The HCl droplets were finally embedded in the ice crystals by further growth of the bunched steps. In contrast, with increasing temperature, the HCl droplets and the bunched steps disappeared at -10 degrees C. Our findings will give significant insights into various environmental issues caused by acidic gases in polar regions.
• First In Situ X-ray Scattering Measurements of Insect Body Surface Lipids: American Cockroach

  Fumitoshi Kaneko, Chihiro Katagiri, Ken Nagashima, Gen Sazaki

  JOURNAL OF PHYSICAL CHEMISTRY LETTERS 12 (7) 1969 - 1972 1948-7185 2021/02 [Refereed]
   

  In situ X-ray scattering measurements of insect body surface lipids were successfully attempted by using a synchrotron X-ray source. The temperature-dependent structural changes of the cuticular hydrocarbons covering the forewing of an American cockroach were able to be followed, which showed that the majority of the hydrocarbons were in a liquid state even far below the critical temperature of water transpiration through the body surface. The results clearly demonstrated that synchrotron radiation X-ray scattering has the potential to obtain the detailed information about the intact lipid structure and physical properties on insect body surfaces.
• Quasi-liquid Layers in Grooves of Grain Boundaries and on Grain Surfaces of Polycrystalline Ice Thin Films

  Jialu Chen, Takao Maki, Ken Nagashima, Ken-ichiro Murata, Gen Sazaki

  CRYSTAL GROWTH & DESIGN 20 (11) 7188 - 7196 1528-7483 2020/11 [Refereed]
   

  In nature, a large proportion of ice is present in a polycrystalline state. Thus, understanding the formation of quasi-liquid layers (QLLs) on/in polycrystalline ice is indispensable for understanding a wide variety of natural phenomena. In this study, we observed surfaces of polycrystalline ice thin films using our advanced optical microscope. We focused our attention on the macroscopic fluidity of objects observed on polycrystalline ice surfaces as evidence for the presence of QLLs. Systematic observations under various temperatures and water vapor pressures showed that, with increasing temperature, QLLs first appeared preferentially in grooves of grain boundaries and continued to exist at -1.9 +/- 0.4 degrees C, irrespective of the water vapor pressure (even in immediate vicinities of the vapor-ice equilibrium curve). From this result, we concluded that the QLLs were formed by melting of grain boundaries to relax lattice mismatches. With a further increase of temperature, droplet-type QLLs appeared on grain surfaces at -0.7 +/- 0.2 degrees C. However, as time elapsed, the droplet-type QLLs on the grain surfaces spontaneously disappeared within 5 +/- 3 min even though temperature and water vapor pressure were kept constant. Such appearance and subsequent disappearance of the droplet-type QLLs on the grain surfaces were observed even under relatively highly supersaturated and undersaturated conditions.
• Quasi-Liquid Layers Can Exist on Polycrystalline Ice Thin Films at a Temperature Significantly Lower than on Ice Single Crystals (vol 19, pg 116, 2019)

  Jialu Chen, Takao Maki, Ken Nagashima, Ken-ichiro Murata, Gen Sazaki

  CRYSTAL GROWTH & DESIGN 20 (7) 4852 - 4854 1528-7483 2020/07
• Appearance and Disappearance of Quasi-Liquid Layers on Ice Crystals in the Presence of Nitric Acid Gas

  Ken Nagashima, Josée Maurais, Ken-ichiro Murata, Yoshinori Furukawa, Patrick Ayotte, Gen Sazaki

  Crystals 10 (2) 72 - 72 2073-4352 2020/01 [Refereed][Not invited]
  
• The Surface of Ice under Equilibrium and Nonequilibrium Conditions

  Yuki Nagata, Tetsuya Hama, Ellen H. G. Backus, Markus Mezger, Daniel Bonn, Mischa Bonn, Gen Sazaki

  ACCOUNTS OF CHEMICAL RESEARCH 52 (4) 1006 - 1015 0001-4842 2019/04 [Refereed]
   

  CONSPECTUS: The ice premelt, often called the quasi-liquid layer (QLL), is key for the lubrication of ice, gas uptake by ice, and growth of aerosols. Despite its apparent importance, in-depth understanding of the ice premelt from the microscopic to the macroscopic scale has not been gained. By reviewing data obtained using molecular dynamics (MD) simulations, sum-frequency generation (SFG) spectroscopy, and laser confocal differential interference contrast microscopy (LCM-DIM), we provide a unified view of the experimentally observed variation in quasi-liquid (QL) states. In particular, we disentangle three distinct types of QL states of disordered layers, QL-droplet, and QL-film and discuss their nature. The topmost ice layer is energetically unstable, as the topmost interfacial H2O molecules lose a hydrogen bonding partner, generating a disordered layer at the ice-air interface. This disordered layer is homogeneously distributed over the ice surface. The nature of the disordered layer changes over a wide temperature range from -90 degrees C to the bulk melting point. Combined MD simulations and SFG measurements reveal that the topmost ice surface starts to be disordered around -90 degrees C through a process that the topmost water molecules with three hydrogen bonds convert to a doubly hydrogen-bonded species. When the temperature is further increased, the second layer starts to become disordered at around -16 degrees C. This disordering occurs not in a gradual manner, but in a bilayer-by-bilayer manner.When the temperature reaches -2 degrees C, more complicated structures, QL-droplet and QL-film, emerge on the top of the ice surface. These QL-droplets and QL-films are inhomogeneously distributed, in contrast to the disordered layer. We show that these QL-droplet and QL-film emerge only under supersaturated/undersaturated vapor pressure conditions, as partial and pseudopartial wetting states, respectively. Experiments with precisely controlled pressure show that, near the water vapor pressure at the vapor-ice equilibrium condition, no QL-droplet and QL-film can be observed, implying that the QL-droplet and QL-film emerge exclusively under nonequilibrium conditions, as opposed to the disordered layers formed under equilibrium conditions.These findings are connected with many phenomena related to the ice surface. For example, we explain how the disordering of the topmost ice surface governs the slipperiness of the ice surface, allowing for ice skating. Further focus is on the gas uptake mechanism on the ice surface. Finally, we note the unresolved questions and future challenges regarding the ice premelt.
• Crystal-plane-dependent effects of antifreeze glycoprotein impurity for ice growth dynamics

  Yoshinori Furukawa, Ken Nagashima, Shunichi Nakatsubo, Salvador Zepeda, Ken-ichiro Murata, Gen Sazaki

  Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377 (2146) 20180393 - 20180393 1364-503X 2019/04 [Refereed][Invited]
  
• Dynamic Properties of Quasi-Liquid Layers on Ice Crystal Surfaces Clarified by Advanced Optical Microscopy

  麻川 明俊, 佐﨑 元, 長嶋 剣, 中坪 俊一, 古川 義純

  Journal of the Society of Inorganic Materials, Japan : セッコウ・石灰・セメント・地球環境の科学 無機マテリアル学会 26 (399) 99 - 104 1345-3769 2019/03 [Refereed][Invited]
  
• How Do Ice Crystals Grow inside Quasiliquid Layers?

  Ken-ichiro Murata, Ken Nagashima, Gen Sazaki

  Physical Review Letters American Physical Society ({APS}) 122 (2) 0031-9007 2019/01 [Refereed][Not invited]
  
• Quasi-liquid layers can exist on polycrystalline ice thin films at a temperature significantly lower than on ice single crystals

  J. Chen, K. Nagashima, K. Murata, G. Sazaki

  Crystal Growth & Design 19 (1) 116 - 124 2019/01 [Refereed][Not invited]
  
• ATR FTIR Spectroscopic Study on Insect Body Surface Lipids Rich in Methylene-Interrupted Diene

  Fumitoshi Kaneko, Chihiro Katagiri, Gen Sazaki, Ken Nagashima

  The Journal of Physical Chemistry B American Chemical Society ({ACS}) 2018/12/27 [Refereed][Not invited]
  
• In situ observations of spiral growth on ice crystal surfaces

  Murata Ken-ichiro, Nagashima Ken, Sazaki Gen

  PHYSICAL REVIEW MATERIALS 2 (9) 2475-9953 2018/09/10 [Refereed][Not invited]
  
• Growth suppression of ice crystal basal face in the presence of a moderate ice-binding protein does not confer hyperactivity

  Bayer-Giraldi Maddalena, Sazaki Gen, Nagashima Ken, Kipfstuhl Sepp, Vorontsov Dmitry A, Furukawa Yoshinori

  PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 115 (29) 7479 - 7484 0027-8424 2018/07/17 [Refereed][Not invited]
  
• Uptake Mechanism of Atmospheric Hydrogen Chloride Gas in Ice Crystals via Hydrochloric Acid Droplets

  Nagashima Ken, Sazaki Gen, Hama Tetsuya, Murata Ken-ichiro, Furukawa Yoshinori

  CRYSTAL GROWTH & DESIGN 18 (7) 4117 - 4122 1528-7483 2018/07 [Refereed][Not invited]
   

  Surfaces of ice have attracted considerable attention as "reaction sites" where atmospheric gases cause various chemical reactions in nature. Hence, revealing the uptake mechanism of atmospheric gases on/in ice remains an experimental challenge. Here we show the direct observation of ice crystal surfaces by advanced optical microscopy in the presence of hydrogen chloride (HCl) gas, which triggers a series of chemical reactions that cause ozone depletion. We found that the HCl gas induced the appearance of droplets of HCl solution on ice crystal surfaces. Under supersaturated water vapor pressure, the HCl droplets were quickly embedded in the ice crystals during the growth of the ice. In contrast, under undersaturated conditions, the embedded HCl droplets reappeared on the ice crystal surfaces during the evaporation of the ice. We estimated that the mole fraction of HCl incorporated into the ice as the HCl droplets (0.19% at -15 degrees C) was ten times larger than the solubility of HCl gas in an ice crystal (0.017%). This picture of the uptake of HCl gas in ice is quite different from the conventional speculation in which HCl gas is confined to ice surfaces.
• Growth of Ice Crystals in the Presence of Type III Antifreeze Protein

  Dmitry A. Vorontsov, Gen Sazaki, Evgeniia K. Titaeva, Ekaterina L. Kim, Maddalena Bayer-Giraldi, Yoshinori Furukawa

  Crystal Growth and Design 18 (4) 2563 - 2571 1528-7505 2018/04/04 [Refereed][Not invited]
   

  The morphology and growth kinetics of ice single crystals in aqueous solutions of type III antifreeze protein (AFP-III) have been studied in detail over a range of AFP-III concentrations and supercoolings. In pure water, the shape of ice crystals changes from the circular disklike to planar dendritic with increasing supercooling. In AFP-III solutions, ice crystals in the form of faceted plates, irregular dendrites with polygonized tips, and needles appear with increasing supercooling and AFP-III concentration. The growth rate of ice crystals in the crystallographic a direction is 2 orders of magnitude higher than that in the c direction. AFP-III molecules cause the stoppage of the growth of the prismatic and basal faces at low supercoolings. When supercooling exceeds the critical value, AFP-III favors the acceleration of the growth in both a and c directions. The observed behavior of AFP-III is explained in terms of the Cabrera-Vermilyea pinning model and the specificity of the dissipation of latent heat from the growing crystals with different shapes.
• Temperature Dependence of the Growth Kinetics of Elementary Spiral Steps on Ice Basal Faces Grown from Water Vapor

  Masahiro Inomata, Ken-ichiro Murata, Harutoshi Asakawa, Ken Nagashima, Shunichi Nakatsubo, Yoshinori Furukawa, Gen Sazaki

  CRYSTAL GROWTH & DESIGN 18 (2) 786 - 793 1528-7483 2018/02 [Refereed][Not invited]
   

  We measured the velocity V-step of isolated elementary spiral steps and the distance L-eq between adjacent equivalent spiral steps on ice basal faces by advanced optical microscopy. We determined the step kinetic coefficient beta from V-step measured under various supersaturations. We performed similar experiments under various temperatures T, and determined the temperature dependence of beta of ice basal faces, for the first time, in the temperature range of -26.0 to 2.7 degrees C. When -6.2 <= T <= 2.7 degrees C, the value of beta decreased significantly with decreasing T. In contrast, when -15.0 <= T <= -6.2 degrees C, the value of beta increased with decreasing T, and had the maximum at T approximate to -15 degrees C. When -26.0 <= T <= 15.0 degrees C, the value of beta decreased monotonically with decreasing T. Such complicated temperature dependence of beta strongly implies the existence of unknown phenomena in the temperature range examined. To obtain a clue to the complicated behavior of beta, we also measured dependence of L-eq on surface supersaturation Aptsurf. When 13.0 <= T <= 3.2 degrees C, plots of L-eq vs 1/Delta mu(surf) satisfactorily follow the spiral growth model. However, when 26.0 <= T <= 15.0 C, the Leq vs 1/Delta mu(surf) plots do not follow any model: this temperature range agrees with the temperature range in which beta decreased monotonically with decreasing T.
• Self-Organized Formation of Parallel-Banded Structures through Synchronization of Twisted Growth

  Shingo Mizue, Shunsuke Ibaraki, Ryuta Ise, Gen Sazaki, Yuya Oaki, Hiroaki Imai

  CRYSTAL GROWTH & DESIGN 17 (7) 3694 - 3699 1528-7483 2017/07 [Refereed][Not invited]
   

  Self-organized formation of parallel-banded structures was demonstrated through the twisted growth of K2Cr2O7 in a thin layer of a viscous solution containing poly(acrylic acid) on a glass substrate. Dense branching of the twisted crystals was induced by increasing their growth rate under a controlled flow of nitrogen gas. Periodically banded structures were then obtained by the synchronization of the twist in the parallel branches. Specific structural colors originating from the parallel-banded structures as a diffraction grating were observed on the self-organized patterns of the twisted crystals.
• Oscillations and accelerations of ice crystal growth rates in microgravity in presence of antifreeze glycoprotein impurity in supercooled water

  Yoshinori Furukawa, Ken Nagashima, Shun-ichi Nakatsubo, Izumi Yoshizaki, Haruka Tamaru, Taro Shimaoka, Takehiko Sone, Etsuro Yokoyama, Salvador Zepeda, Takanori Terasawa, Harutoshi Asakawa, Ken-ichiro Murata, Gen Sazaki

  SCIENTIFIC REPORTS 7 2045-2322 2017/03 [Refereed][Not invited]
   

  The free growth of ice crystals in supercooled bulk water containing an impurity of glycoprotein, a bio-macromolecule that functions as 'antifreeze' in living organisms in a subzero environment, was observed under microgravity conditions on the International Space Station. We observed the acceleration and oscillation of the normal growth rates as a result of the interfacial adsorption of these protein molecules, which is a newly discovered impurity effect for crystal growth. As the convection caused by gravity may mitigate or modify this effect, secure observations of this effect were first made possible by continuous measurements of normal growth rates under long-term microgravity condition realized only in the spacecraft. Our findings will lead to a better understanding of a novel kinetic process for growth oscillation in relation to growth promotion due to the adsorption of protein molecules and will shed light on the role that crystal growth kinetics has in the onset of the mysterious antifreeze effect in living organisms, namely, how this protein may prevent fish freezing.
• Thermodynamic origin of surface melting on ice crystals

  Ken-ichiro Murata, Harutoshi Asakawa, Ken Nagashima, Yoshinori Furukawa, Gen Sazaki

  PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 113 (44) E6741 - E6748 0027-8424 2016/11 [Refereed][Not invited]
   

  Since the pioneering prediction of surface melting by Michael Faraday, it has been widely accepted that thin water layers, called quasi-liquid layers (QLLs), homogeneously and completely wet ice surfaces. Contrary to this conventional wisdom, here we both theoretically and experimentally demonstrate that QLLs have more than two wetting states and that there is a first-order wetting transition between them. Furthermore, we find that QLLs are born not only under supersaturated conditions, as recently reported, but also at undersaturation, but QLLs are absent at equilibrium. This means that QLLs are a metastable transient state formed through vapor growth and sublimation of ice, casting a serious doubt on the conventional understanding presupposing the spontaneous formation of QLLs in ice-vapor equilibrium. We propose a simple but general physical model that consistently explains these aspects of surface melting and QLLs. Our model shows that a unique interfacial potential solely controls both the wetting and thermodynamic behavior of QLLs.
• Preface

  G. Sazaki, H. Nada, S. Naritsuka

  Progress in Crystal Growth and Characterization of Materials 62 (2) 41 - 42 0960-8974 2016/06 [Refereed][Not invited]
  
• In-situ observation of crystal surfaces by optical microscopy

  Gen Sazaki, Ken Nagashima, Ken-ichiro Murata, Yoshinori Furukawa

  PROGRESS IN CRYSTAL GROWTH AND CHARACTERIZATION OF MATERIALS 62 (2) 408 - 412 0960-8974 2016/06 [Refereed][Not invited]
   

  In this experimental course, attendees will learn how to obtain useful information about growth processes of crystals using ordinary optical microscopes, which are usually available in laboratories. We will demonstrate how thicknesses of crystals can be estimated from interference colors. We will also show in-situ observations of spiral steps and strain distributions by differential interference contrast microscopy and polarizing microscopy, respectively. (C) 2016 Elsevier Ltd. All rights reserved.
• Special issue: Recent Progress on Fundamentals and Applications of Crystal Growth; Proceedings of the 16th International Summer School on Crystal Growth (ISSCG-16) Preface

  G. Sazaki, H. Nada, S. Naritsuka

  PROGRESS IN CRYSTAL GROWTH AND CHARACTERIZATION OF MATERIALS 62 (2) 41 - 42 0960-8974 2016/06 [Refereed][Not invited]
  
• Direct Visualization of Quasi-Liquid Layers on Ice Crystal Surfaces Induced by Hydrogen Chloride Gas

  Ken Nagashima, Gen Sazaki, Tetsuya Hama, Harutoshi Asakawa, Ken-ichiro Murata, Yoshinori Furukawa

  CRYSTAL GROWTH & DESIGN 16 (4) 2225 - 2230 1528-7483 2016/04 [Refereed][Not invited]
   

  Surface melting of ice crystals forms quasi liquid layers (QLLs) on ice surfaces, and affects a wide variety of natural phenomena. Since QLLs enhance various chemical reactions in ice clouds, the formation of QLLs by atmospheric gases has been studied intensively. However, such studies were performed using spectroscopy techniques, which have low spatial resolution. Here we show the first direct-visualization of QLLs on ice basal faces in the presence of hydrogen chloride (HCl) gas (model atmospheric gas) by advanced optical microscopy, which can visualize individual 0.37 nm-thick elementary steps on ice crystal surfaces. We found that the HCl gas induced the appearances of QLLs with a droplet shape in the temperature range from -15.0 to -1.5 degrees C, where no QLL appears in the absence of HCl gas. This result indicates that HCl gas adsorbed on ice crystal surfaces probably changed the surface structure of ice crystals and then induced the subsequent melting of ice surfaces. We also observed the movement, shape change, and splitting of the droplet QLLs when water vapor was undersaturated. The long-term (1 h) existence of the droplet QLLs under the undersaturated conditions strongly suggests that the droplet QLLs were thermodynamically stable HCl solutions.
• Two types of quasi-liquid layers on ice crystals are formed kinetically

  Harutoshi Asakawa, Gen Sazaki, Ken Nagashima, Shunichi Nakatsubo, Yoshinori Furukawa

  PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 113 (7) 1749 - 1753 0027-8424 2016/02 [Refereed][Not invited]
   

  Surfaces of ice are covered with thin liquid water layers, called quasi-liquid layers (QLLs), even below their melting point (0 degrees C), which govern a wide variety of phenomena in nature. We recently found that two types of QLL phases appear that exhibit different morphologies (droplets and thin layers) [Sazaki G. et al. (2012) Proc Natl Acad Sci USA 109(4):1052-1055]. However, revealing the thermodynamic stabilities of QLLs remains a longstanding elusive problem. Here we show that both types of QLLs are metastable phases that appear only if the water vapor pressure is higher than a certain critical supersaturation. We directly visualized the QLLs on ice crystal surfaces by advanced optical microscopy, which can detect 0.37-nm-thick elementary steps on ice crystal surfaces. At a certain fixed temperature, as the water vapor pressure decreased, thin-layer QLLs first disappeared, and then droplet QLLs vanished next, although elementary steps of ice crystals were still growing. These results clearly demonstrate that both types of QLLs are kinetically formed, not by the melting of ice surfaces, but by the deposition of supersaturated water vapor on ice surfaces. To our knowledge, this is the first experimental evidence that supersaturation of water vapor plays a crucially important role in the formation of QLLs.
• 21aBE-6 A simple physical model for surface melting of ice crystals

  Murata K., Asakawa H., Nagashima K., Furukawa Y., Sazaki G.

  Meeting Abstracts of the Physical Society of Japan 一般社団法人日本物理学会 71 2608 - 2608 2189-079X 2016
• 21aBE-5 Water Vapor Pressure Dependency of Behavior of hydrochloric acid droplets on Ice Crystal Surfaces

  Nagashima K., Sazaki G., Hama T., Murata K., Furukawa Y.

  Meeting Abstracts of the Physical Society of Japan 一般社団法人日本物理学会 71 2607 - 2607 2189-079X 2016
• In-situ measurements of velocity and spacing of elementary steps on ice basal faces

  Inomata Masahiro, Nagashima Ken, Murata Ken-ichiro, Sazaki Gen

  Meeting Abstracts of the Physical Society of Japan 一般社団法人 日本物理学会 71 2458 - 2458 2016 

  氷結晶ベーサル面上で単位ステップを光学その場観察し、ステップ前進速度とステップ間隔を計測した。講演では、これらの物理量と過飽和との相関を報告する。

• In situ Determination of Surface Tension-to-Shear Viscosity Ratio for Quasiliquid Layers on Ice Crystal Surfaces

  Ken-Ichiro Murata, Harutoshi Asakawa, Ken Nagashima, Yoshinori Furukawa, Gen Sazaki

  Physical Review Letters 115 (25) 1079-7114 2015/12/17 [Refereed][Not invited]
   

  We have experimentally determined the surface tension-to-shear viscosity ratio (the so-called characteristic velocity) of quasiliquid layers (QLLs) on ice crystal surfaces from their wetting dynamics. Using an advanced optical microscope, whose resolution reaches the molecular level in the height direction, we directly observed the coalescent process of QLLs and followed the relaxation modes of their contact lines. The relaxation dynamics is known to be governed by the characteristic velocity, which allows us to access the physical properties of QLLs in a noninvasive way. Here we quantitatively demonstrate that QLLs, when completely wetting ices, have a thickness of 9±3 nm and an approximately 200 times lower characteristic velocity than bulk water, whereas QLLs, when partially wetting ices, have a velocity that is 20 times lower than the bulk. This indicates that ice crystal surfaces significantly affect the physical properties of QLLs localized near the surfaces at a nanometer scale.
• Prism and Other High-Index Faces of Ice Crystals Exhibit Two Types of Quasi-Liquid Layers

  Harutoshi Asakawa, Gen Sazaki, Ken Nagashima, Shunichi Nakatsubo, Yoshinori Furukawa

  CRYSTAL GROWTH & DESIGN 15 (7) 3339 - 3344 1528-7483 2015/07 [Refereed][Not invited]
   

  Surface melting of ice significantly governs a wide variety of phenomena in nature. We recently succeeded in directly observing the surface melting on ice basal faces (Proc. Natl. Acad. Sci. U.S.A. 2012, 109, 1052-1055) by our advanced optical microscopy, which can detect 0.37-nm-thick elementary steps on basal faces. However, the direct observation of surface melting on the other prism and high-index faces remains an experimental challenge. To fully obtain a comprehensive understanding, we need to examine the surface melting on these faces. Here we show the appearance of two types of quasi-liquid layers (QLLs) on prism and high-index faces just below the melting point. We quickly raised the temperature of ice crystals and then observed prism and high-index faces during a roughening process. We found that with increasing temperature, round liquid-like droplets (alpha-QLLs) first appeared at temperatures higher than -1.4 to -0.5 degrees C, and then thin liquid-like layers (beta-QLLs) also appeared at temperatures higher than -0.8 to -0.3 degrees C, as in the case of basal faces. This result demonstrates that the presence of two types of QLL phases with different morphologies plays an intrinsically important role in the surface melting of ice crystals, irrespective of face indexes. We also revealed that the roughening process was caused thermally.
• Direct observation of bunching of elementary steps on protein crystals under forced flow conditions

  Gen Sazaki, Guoliang Dai

  Theoretical and Applied Mechanics Letters 5 (4) 173 - 176 2095-0349 2015/07/01 [Refereed][Not invited]
   

  Bunching of elementary steps by solution flow is still not yet clarified for protein crystals. Hence, in this study, we observed elementary steps on crystal surfaces of model protein hen egg-white lysozyme (HEWL) under forced flow conditions, by our advanced optical microscopy. We found that in the case of a HEWL solution of 99.99% purity, forced flow changed bunched steps into elementary ones (debunching) on tetragonal HEWL crystals. In contrast, in the case of a HEWL solution of 98.5% purity, forced flow significantly induced bunching of elementary steps. These results indicate that in the case of HEWL crystals, the mass transfer of impurities is more significantly enhanced by forced solution flow than that of solute HEWL molecules. We also showed that forced flow induced the incorporation of microcrystals into a mother crystal and the subsequent formation of screw dislocations and spiral growth hillocks.
• 17aCB-1 Liquid Layer on Ice Surfaces Induced by Hydrochloric Gas

  Nagashima K., Sazaki G., Hama T., Murata K., Nakatsubo S., Furukawa Y.

  Meeting Abstracts of the Physical Society of Japan 一般社団法人日本物理学会 70 2266 - 2266 2189-079X 2015
• 22aAE-9 Effect of Hydrogen Chloride on an Ice Basal face

  Nagashima K., Sazaki G., Hama T., Asakawa H., Murata K., Nakatsubo S., Furukawa Y.

  Meeting Abstracts of the Physical Society of Japan 一般社団法人日本物理学会 70 2601 - 2601 2189-079X 2015
• 21aAE-11 Hierarchical dynamics in melting processes

  Murata K., Asakawa H., Nagashima K., Furukawa Y., Sazaki G.

  Meeting Abstracts of the Physical Society of Japan 一般社団法人日本物理学会 70 2514 - 2514 2189-079X 2015
• Oscillatory growth for twisting crystals

  Shunsuke Ibaraki, Ryuta Ise, Koichiro Ishimori, Yuya Oaki, Gen Sazaki, Etsuro Yokoyama, Katsuo Tsukamoto, Hiroaki Imai

  CHEMICAL COMMUNICATIONS 51 (40) 8516 - 8519 1359-7345 2015 [Refereed][Not invited]
   

  We demonstrate the oscillatory phenomenon for the twisting growth of a triclinic crystal through in situ observation of the concentration field around the growing tip of a needle by high-resolution phase-shift interferometry.
• 氷ベーサル面上での形態が異なる2種類の擬似液体層の生成過程

  佐﨑元, 麻川明俊, 長嶋剣, 中坪俊一, 古川義純

  International Journal of Microgravity Science Application 31 (3) 100 - 105 2014/10/01 [Not refereed][Not invited]
  
• Attachment and Detachment Processes of Individual Lysozyme Molecules on a Surface of a Monoclinic Lysozyme Crystal Studied by Fluorescent Single-Molecule Visualization

  Guoliang Dai, Lei Zheng, Gen Sazaki, Yoshinori Furukawa

  CRYSTAL GROWTH & DESIGN 14 (10) 5303 - 5309 1528-7483 2014/10 [Refereed][Not invited]
   

  On a {10 (1) over bar} face of a monoclinic crystal of hen egg-white lysozyme (HEWL), we visualized the attachment and detachment processes of individual fluorescent-labeled HEWL (F-HEWL) molecules by a fluorescent single-molecule visualization technique. We measured the changes in number density of F-HEWL molecules, whose positions were not changed for longer than a certain residence time, as a function of an adsorption time. We first confirmed that under an equilibrium condition, there was an induction period (similar to 120 min) of the attachment/detachment processes, during which period the number density remained constant. After the induction period, the number density increased linearly with the adsorption time, as it was recently found on a tetragonal HEWL crystal [Dai, G. L. Cryst. Growth Des 2011, 11 (1), 88-92]. In addition, we performed similar measurements under a supersaturated condition. Then we found that supersaturation significantly enhanced the attachment process after the induction time. The attachment/detachment processes finally reached a steady state, in which the attachment rate was higher than the detachment one. Moreover, we also found that in a rare case, an F-HEWL molecule adsorbed on a step laterally moved following the advancement of a growing step.
• Antifreeze Effect of Carboxylated epsilon-Poly-L-lysine on the Growth Kinetics of Ice Crystals

  Dmitry A. Vorontsov, Gen Sazaki, Suong-Hyu Hyon, Kazuaki Matsumura, Yoshinori Furukawa

  JOURNAL OF PHYSICAL CHEMISTRY B 118 (34) 10240 - 10249 1520-6106 2014/08 [Refereed][Not invited]
   

  Some biological substances control the nucleation and growth of inorganic crystals. Antifreeze proteins, which prohibit ice crystal growth in living organisms, promise are also important as biological antifreezes for medical applications and in the frozen food industries. In this work, we investigated the crystallization of ice in the presence of a new cryoprotector, carboxylated epsilon-poly-L-lysine (COOH-PLL). In order to reveal the characteristics and the mechanism of its antifreeze effect, free-growth experiments of ice crystals were carried out in solutions with various COOH-PLL concentrations and degrees of supercooling, and the depression of the freezing point and growth rates of the tips of ice dendrites were obtained using optical microscopy. Hysteresis of growth rates and depression of the freezing point was revealed in the presence of COOH-PLL. The growth-inhibition effect of COOH-PLL molecules could be explained on the basis of the Gibbs-Thomson law and the use of Langmuir's adsorption isotherm. Theoretical kinetic curves for hysteresis calculated on the basis of Punin-Artamonova's model were in good agreement with experimental data. We conclude that adsorption of large biological molecules in the case of ice crystallization has a non-steady-state character and occurs more slowly than the process of embedding of crystal growth units.
• Roles of Surface/Volume Diffusion in the Growth Kinetics of Elementary Spiral Steps on Ice Basal Faces Grown from Water Vapor

  Harutoshi Asakawa, Gen Sazaki, Etsuro Yokoyama, Ken Nagashima, Shunichi Nakatsubo, Yoshinori Furukawa

  CRYSTAL GROWTH & DESIGN 14 (7) 3210 - 3220 1528-7483 2014/07 [Refereed][Not invited]
   

  We measured velocities V-step of lateral displacement of individual elementary steps on an ice basal face, for the first time, by advanced optical microscopy, under various bulk water vapor pressure p(H2O)(infinity). Distances L between adjacent spiral steps exhibited considerable variation under constant p(H2O)(infinity). Hence, we analyzed V-step as functions of L and p(H2O)(infinity). Then we found that (1) under a constant p(H2O)(infinity), V-step decreased with decreasing distances L when L <= 15 mu m and that V-step remained constant when L >= 15 mu m. We named V-step of L >= 15 mu m (isolated steps) V-step(int) and analyzed dependencies of V-step(int) on p(H2O)(infinity). Then we found that (2) the slope of the V-step(int) vs p(H2O)(infinity) plot gradually decreased with increasing p(H2O)(infinity). We proposed a model that took into account both the volume diffusion of water vapor molecules and the surface diffusion of water admolecules on a terrace. Our model could explain result (1) mainly by the competition of adjacent spiral steps for water admolecules diffusing on a terrace but could not explain the result (2) satisfactorily.
• Double Spiral Steps on I-h Ice Crystal Surfaces Grown from Water Vapor Just below the Melting Point

  Gen Sazaki, Harutoshi Asakawa, Ken Nagashima, Shunichi Nakatsubo, Yoshinori Furukawa

  CRYSTAL GROWTH & DESIGN 14 (5) 2133 - 2137 1528-7483 2014/05 [Refereed][Not invited]
   

  During the growth of ice crystals, spiral growth is one of the important growth mechanisms that dominate their growth. However, the structure of spiral steps on ice crystal surfaces at temperatures near the melting point has not been identified. Here we show a possible model structure of spiral steps on basal and prism faces of I-h ice crystals grown from water vapor just below 0 degrees C. We observed in situ the coalescences of spiral steps and steps of two-dimensional (2D) islands by our advanced optical microscopy, which can visualize individual elementary steps (single-bilayer height) of 2D islands on ice basal faces. We found that both spiral steps and 2D island steps on basal and prism faces show single-bilayer heights, though Burgers' vectors of screw dislocations on both faces need to have double-bilayer heights because of a crystallographic requirement. These results suggest that at the center of a spiral growth hillock, steps of two adjacent single bilayers coincide and then form a double-bilayer step and that the steps of two single bilayers gradually detach themselves with increasing radii of their spiral steps. We observed the appearance of double spiral steps, which strongly supports our model structure, at -15.0 degrees C (the lowest temperature of our setup).
• High Contrast Visualization of Cell-Hydrogel Contact by Advanced Interferometric Optical Microscopy

  Takahisa Matsuzaki, Gen Sazaki, Masami Suganuma, Tatsuro Watanabe, Takashi Yamazaki, Motomu Tanaka, Seiichiro Nakabayashi, Hiroshi Y. Yoshikawa

  JOURNAL OF PHYSICAL CHEMISTRY LETTERS 5 (1) 253 - 257 1948-7185 2014/01 [Refereed][Not invited]
   

  Hydrogels with tunable elasticity has been widely used as micromechanical environment models for cells. However, the imaging of physical contacts between cells and hydrogels with a nanometer resolution along the optical axis remain challenging because of low reflectivity at hydrogel-liquid interface. In this work, we have developed an advanced interferometric optical microscopy for the high contrast visualization of cell-hydrogel contact. Here, reflection interference contrast microscopy (RICM) was modified with a confocal unit, high throughput optics and coherent monochromatic light sources to enhance interferometric signals from cell-hydrogel contact zones. The advanced interferomety clearly visualized physical contacts between cells and hydrogels, and thus enabled the quantitative evaluation of the area of cell-hydrogel adhesion.
• Colloidal crystallization utilizing interfaces of unidirectionally growing ice crystals

  Yoshihisa Suzuki, Gen Sazaki, Kaori Hashimoto, Takahisa Fujiwara, Yoshinori Furukawa

  JOURNAL OF CRYSTAL GROWTH 383 67 - 71 0022-0248 2013/11 [Refereed][Not invited]
   

  We show the possibility of unidirectional freezing of colloidal random suspensions as a novel method for growing colloidal crystals. First we confirmed the rejection of polystyrene particles from unidirectionally growing ice water interfaces by observing color gradations of colloidal crystals formed in front of the interfaces. The rejection of particles from the growing interfaces increased particle concentration in the colloidal crystals. Then we succeeded in achieving colloidal crystallization in front of ice water interfaces during the unidirectional freezing of water suspensions of polystyrene particles. The colloidal crystals thus brained exhibited a columnar shape that is typically observed in the unidirectional colloidal crysrallizarion using centrifugation. (C) 2013 Elsevier B.V. All rights reserved.
• Protein Crystal Growth under a Forced Solution Flow

  丸山美帆子, 中村真利子, 佐崎元, 高橋義典, 吉村政志, 吉川洋史, 杉山成, 安達宏昭, 松村浩由, 井上豪, 高野和文, 村上聡, 森勇介

  日本結晶成長学会誌 40 (2) 72 - 82 0385-6275 2013/07 [Not refereed][Not invited]
  
• A Novel Approach for Protein Crystallization by a Synthetic Hydrogel with Thermoreversible Gelation Polymer

  Shigeru Sugiyama, Noriko Shimizu, Gen Sazaki, Mika Hirose, Yoshinori Takahashi, Mihoko Maruyama, Hiroyoshi Matsumura, Hiroaki Adachi, Kazufumi Takano, Satoshi Murakami, Tsuyoshi Inoue, Yusuke Mori

  CRYSTAL GROWTH & DESIGN 13 (5) 1899 - 1904 1528-7483 2013/05 [Refereed][Not invited]
   

  Agarose has been utilized in protein crystallization to control nucleation of protein crystals. It reduces convection, prevents crystal sedimentation, and increases tolerance to environmental perturbations, resulting in high-quality protein crystals. However, crystallographers have seldom used agarose hydrogel because it requires preincubating the crystallization solution at high temperatures where a high-temperature-sensitive protein may be inactivated or aggregated. To overcome this disadvantage, we used a thermoreversible gel polymer (TGP) made from synthetic polymer. TGP turns into hydrogel upon warming and liquefies upon cooling. This novel approach enabled us to prepare the crystallization solutions at low temperature (277-283 K) and to crystallize elastase, glucose isomerase, and lysozyme with TGP. We also found that TGP clearly increased the number of elastase, glucose isomerase, and lysozyme crystals. This approach will provide a wide variety of possibilities for protein crystallization in hydrogels.
• How do Quasi-Liquid Layers Emerge from Ice Crystal Surfaces?

  Gen Sazaki, Harutoshi Asakawa, Ken Nagashima, Shunichi Nakatsubo, Yoshinori Furukawa

  CRYSTAL GROWTH & DESIGN 13 (4) 1761 - 1766 1528-7483 2013/04 [Refereed][Not invited]
   

  Ice crystal surfaces melt at temperatures below 0 degrees C, and then quasi-liquid layers (QLLs) are formed. However, revealing the dynamic behavior of QLLs, which dominates the surface properties of ice crystals at temperatures near the melting point, remains an experimental challenge. Here, we demonstrate the similarities and differences in the generation mechanisms of two types of QLL phases, which show different morphologies and dynamics. We directly visualized the appearance of round liquidlike droplets (alpha-QLLs) and thin liquidlike layers (beta-QLLs) on ice basal faces by advanced optical microscopy, which can allow visualization of the individual elementary steps on basal faces. We found that alpha-QLLs always appear at outcrops of dislocations, and that beta-QLLs emerge from crystal surfaces where many microdefects are embedded. These results clearly demonstrate the similar function that strain induces the appearance of both types of QLLs. We also found that beta-QLLs are spontaneously formed at interfaces between basal faces and alpha-QLLs, when the diameter of the alpha-QLLs becomes larger than several tens of micrometers. This result arose from the different structures of alpha- and beta-QLLs: the beta-QLLs probably have a structure intermediate between those of basal faces and alpha-QLLs, resulting in a reduction of the total interfacial free energy.
• Elementary Growth Processes and Surface Melting of Ice Crystals Revealed by Advanced Optical Microscopy

  Gen Sazaki, Zepeda Salvador, Shunichi Nakatsubo, Yoshinori Furukawa

  JOURNAL OF THE JAPANESE SOCIETY FOR FOOD SCIENCE AND TECHNOLOGY-NIPPON SHOKUHIN KAGAKU KOGAKU KAISHI 60 (8) 445 - 449 1341-027X 2013 [Refereed][Not invited]
   

  Molecular-level understanding of ice crystal surfaces holds the key to unlocking the secrets of various fields. To observe ice crystal surfaces at the molecular level, we developed an advanced optical microscope, and succeeded in visualizing individual elementary steps of 0.37 nm in height on ice basal faces. Utilizing this microscope, we also attempted to visualize the surface melting processes of ice crystals. We found the presence of two types of surface liquid phases (quasi-liquid layer phases) that exhibit different morphologies and dynamics on ice basal faces.
• Growth of Protein Crystals in Hydrogels with High Strength

  SUGIYAMA Shigeru, HIROSE Mika, SAZAKI Gen, ADACHI Hiroaki, TAKANO Kazufumi, MURAKAMI Satoshi, MATSUMURA Hiroyoshi, MARUYAMA Mihoko, INOUE Tsuyoshi, MORI Yusuke

  X-RAYS The Crystallographic Society of Japan 54 (5) 300 - 303 0369-4585 2012/10/31 

  High-throughput X-ray protein crystallography offers unprecedented facilitation to structure based drug discovery. The popular way to prepare crystals of target protein in complex with a candidate compound is the soaking method. However, the method often causes damage due to osmotic pressure to crystals, especially when a compound is dissolved in an organic solvent or solution with high ionic strength. These solutions damage protein crystals by osmotic shock. To overcome this difficulty, we have developed a novel technique to grow protein crystals in the concentrated hydrogel. Here, we demonstrate that protein crystals grown in hydrogel are stable to soaking and suffer less damage.
• Spatially Precise, Soft Microseeding of Single Protein Crystals by Femtosecond Laser Ablation

  Hiroshi Y. Yoshikawa, Yoichiroh Hosokawa, Ryota Murai, Gen Sazaki, Tomoya Kitatani, Hiroaki Adachi, Tsuyoshi Inoue, Hiroyoshi Matsumura, Kazufumi Takano, Satoshi Murakami, Seiichiro Nakabayashi, Yusuke Mori, Hiroshi Masuhara

  CRYSTAL GROWTH & DESIGN 12 (9) 4334 - 4339 1528-7483 2012/09 [Refereed][Not invited]
   

  We developed a spatially precise, soft microseeding method for the production of single protein crystals that are suitable for X-ray crystallographic studies. We used focused femtosecond laser pulses to produce, via multiphoton absorption processes, seed crystals from small regions (similar to 1 mu m(2)) of crystals. Hen egg-white lysozyme seed crystals, produced in this manner, grew to be single crystals without any deterioration in their crystallinity. We also validated the technique using polycrystals for the membrane protein, acriflavine resistance protein B, for which single crystals are very difficult to obtain. In addition, we found that the shape of a tetragonal lysozyme crystal prepared from the seed could be controlled by altering the time interval between the initiation of crystallization and laser ablation. We also tried to comprehend the mechanism of femtosecond laser-induced microseeding. We visualized the ablated surfaces of the lysozyme crystals by atomic force microscopy and by laser confocal microscopy combined with differential interference microscopy. The results obtained in this study clearly demonstrate that femtosecond laser ablation of protein crystals is based on a photomechanical process, which ejects crystal fragments with little thermal damage. Femtosecond laser ablation is indeed very promising to produce high quality protein seed crystals from polycrystals or cracked crystals that are not suitable for X-ray diffraction studies.
• In Situ Observation of Elementary Growth Processes of Protein Crystals by Advanced Optical Microscopy

  Gen Sazaki, Alexander E. S. Van Driessche, Guoliang Dai, Masashi Okada, Takuro Matsui, Fermin Otalora, Katsuo Tsukamoto, Kazuo Nakajima

  PROTEIN AND PEPTIDE LETTERS 19 (7) 743 - 760 0929-8665 2012/07 [Refereed][Not invited]
   

  To start systematically investigating the quality improvement of protein crystals, the elementary growth processes of protein crystals must be first clarified comprehensively. Atomic force microscopy (AFM) has made a tremendous contribution toward elucidating the elementary growth processes of protein crystals and has confirmed that protein crystals grow layer by layer utilizing kinks on steps, as in the case of inorganic and low-molecular-weight compound crystals. However, the scanning of the AFM cantilever greatly disturbs the concentration distribution and solution flow in the vicinity of growing protein crystals. AFM also cannot visualize the dynamic behavior of mobile solute and impurity molecules on protein crystal surfaces. To compensate for these disadvantages of AFM, in situ observation by two types of advanced optical microscopy has been recently performed. To observe the elementary steps of protein crystals noninvasively, laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM) was developed. To visualize individual mobile protein molecules, total internal reflection fluorescent (TIRF) microscopy, which is widely used in the field of biological physics, was applied to the visualization of protein crystal surfaces. In this review, recent progress in the noninvasive in situ observation of elementary steps and individual mobile protein molecules on protein crystal surfaces is outlined.
• Effects of a Forced Solution Flow on the Step Advancement on {110} Faces of Tetragonal Lysozyme Crystals: Direct Visualization of Individual Steps under a Forced Solution Flow

  Mihoko Maruyama, Hisato Kawahara, Gen Sazaki, Syou Maki, Yoshinori Takahashi, Hiroshi Y. Yoshikawa, Shigeru Sugiyama, Hiroaki Adachi, Kazufumi Takano, Hiroyoshi Matsumura, Tsuyoshi Inoue, Satoshi Murakami, Yusuke Mori

  CRYSTAL GROWTH & DESIGN 12 (6) 2856 - 2863 1528-7483 2012/06 [Refereed][Not invited]
   

  To grow protein crystals of better quality, there still exists an open question whether a solution flow should be suppressed or intentionally introduced. To obtain a comprehensive understanding of the effects of a solution flow, we directly measured the velocities of individual elementary steps (on {110} faces of tetragonal lysozyme crystals) under a forced solution flow, for the first time, by laser confocal microscopy combined with differential interference contrast microscopy. When we used crystals grown by a two-dimensional (2D) nucleation growth mechanism in a solution of commercial lysozyme (98.5% purity, from Seikagaku Co.), while increasing the solution flow rate, the step velocity decreased monotonically. We confirmed that this decrease in the step velocity with flow rate was due to the enhancement of the mass transfer of impurity (mainly covalently bonded dimer), by the observation using a lysozyme further purified (dimer was removed). In contrast, when we used crystals grown by a spiral growth mechanism in a commercial lysozyme solution, with increasing the flow rate, the step velocity increased and had the maximum at the flow rate of 10 mu m/s; and then decreased monotonically. Also, the step velocity was 2-4 times higher than in the case of the 2D nucleation growth. These results demonstrate that the growth of spiral steps is less affected by impurities because the density of spiral steps is much higher than that of 2D island ones.
• Spiral-Mediated Growth Can Lead to Crystals of Higher Purity

  Mike Sleutel, Gen Sazaki, Alexander E. S. Van Driessche

  CRYSTAL GROWTH & DESIGN 12 (5) 2367 - 2374 1528-7483 2012/05 [Refereed][Not invited]
   

  The morphology and step kinetics of 2D islands and spiral hillocks of lysozyme crystals growing from purified and contaminated solutions were determined and compared. It was found that the morphology and step dynamics of spiral hillocks of lysozyme crystals are less affected by the presence of impurities in the growth solution as compared to steps generated by 2D nucleation. These observations could be satisfactorily explained considering the terrace exposure time of spiral hillocks (tau(sp)) and 2D islands (tau(2D)) and the characteristic impurity adsorption time (tau(i)). For lysozyme, overlapping time scales of terrace exposure and impurity adsorption exist and tau(i) approximate to tau(sp) < tau(2D). Hence, when crystal growth is dominated by spiral hillocks, less impurities are adsorbed onto the crystal surface and a more pure crystal lattice is formed. Although spiral hillocks reduce the effect of impurities, they do play a significant role in the mechanism of step bunching.
• Growth of Protein Crystals in Hydrogels Prevents Osmotic Shock

  Shigeru Sugiyama, Mihoko Maruyama, Gen Sazaki, Mika Hirose, Hiroaki Adachi, Kazufumi Takano, Satoshi Murakami, Tsuyoshi Inoue, Yusuke Mori, Hiroyoshi Matsumura

  JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 134 (13) 5786 - 5789 0002-7863 2012/04 [Refereed][Not invited]
   

  High-throughput protein X-ray crystallography offers a significant opportunity to facilitate drug discovery. The most reliable approach is to determine the three-dimensional structure of the protein ligand complex by soaking the ligand in apo crystals. However, protein apo crystals produced by conventional crystallization in a solution are fatally damaged by osmotic shock during soaking. To overcome this difficulty, we present a novel technique for growing protein crystals in a high-concentration hydrogel that is completely gellified and exhibits high strength. This technique allowed us essentially to increase the mechanical stability of the crystals, preventing serious damage to the crystals caused by osmotic shock. Thus, this method may accelerate structure-based drug discoveries.
• Quasi-liquid layers on ice crystal surfaces are made up of two different phases

  Gen Sazaki, Salvador Zepeda, Shunichi Nakatsubo, Makoto Yokomine, Yoshinori Furukawa

  PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 109 (4) 1052 - 1055 0027-8424 2012/01 [Refereed][Not invited]
   

  Ice plays crucially important roles in various phenomena because of its abundance on Earth. However, revealing the dynamic behavior of quasi-liquid layers (QLLs), which governs the surface properties of ice crystals at temperatures near the melting point, remains an experimental challenge. Here we show that two types of QLL phases appear that exhibit different morphologies and dynamics. We directly visualized the two types of QLLs on ice crystal surfaces by advanced optical microscopy, which can visualize the individual 0.37-nm-thick elementary steps on ice crystal surfaces. We found that they had different stabilities and different interactions with ice crystal surfaces. The two immiscible QLL phases appeared heterogeneously, moved around, and coalesced dynamically on ice crystal surfaces. This picture of surface melting is quite different from the conventional picture in which one QLL phase appears uniformly on ice crystal surfaces.
• Anomalous Diffusion in Supported Lipid Bilayers Induced by Oxide Surface Nanostructures

  Ryugo Tero, Gen Sazaki, Tom Ujihara, Tsuneo Urisu

  LANGMUIR 27 (16) 9662 - 9665 0743-7463 2011/08 [Refereed][Not invited]
   

  Hierarchic structure and anomalous diffusion on submicrometer scale were introduced into an artificial cell membrane, and the spatiotemporal dependence of lipid diffusion was visualized on nanostructured oxide surfaces. We observed the lipid diffusion in supported lipid bilayers (SLBs) on step-and-terrace TiO2(100) and amorphous SiO2/Si surfaces by single molecule tracking (SMT) method. The SMT at the time resolution of 500 mu s to 30 ms achieved observation of the lipid diffusion over the spatial and temporal ranges of 100 nm/millisecond to 1 mu m/second. The temporal dependence of the diffusion coefficient in the SLB on TiO2(100) showed that the crossover from anomalous diffusion to random diffusion occurred around 10 ms. The surface fine architecture on substrates will be applicable to induce hierarchic structures on the order of 100 nm or less, which correspond to the microcompartment size in vivo.
• \Anomalous diffusion in supported lipid bilayers induced by oxide surface nanostructures: Single molecule tracking on opaque and highly-refractive substrates

  Ryugo Tero, Gen Sazaki, Toru Ujihara, Tsuneo Urisu

  ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 242 0065-7727 2011/08 [Refereed][Not invited]
  
• Effect of Evaporation on Protein Crystals Grown in Semi-Solid Agarose Hydrogel

  Shigeru Sugiyama, Mika Hirose, Noriko Shimizu, Mayumi Niiyama, Mihoko Maruyama, Gen Sazaki, Ryota Murai, Hiroaki Adachi, Kazufumi Takano, Satoshi Murakami, Tsuyoshi Inoue, Yusuke Mori, Hiroyoshi Matsumura

  JAPANESE JOURNAL OF APPLIED PHYSICS 50 (2) 0021-4922 2011/02 [Refereed][Not invited]
   

  High-accuracy X-ray diffraction measurements of protein crystals are an important process to determine three-dimensional structures. Investigators must manipulate crystals in X-ray diffraction measurement. Protein crystals are exposed to evaporation during manipulation, and their exposure to evaporation for a long time causes serious damage. Recently, we have developed a novel technique of protein crystallization using a semi-solid agarose gel (SSAG), which demonstrated several desirable merits such as the growth of crystals with high quality, growth with a high nucleation rate, and the possibility of automated crystal capture. To further assess the merits of SSAG-grown crystals, we evaluated the effects of evaporation on the quality of SSAG-grown crystals using X-ray diffraction and subsequent structural analyses. The results demonstrate that the SSAG-grown crystals showed a high tolerance to evaporation, compared with the solution-grown crystals. These comparative experiments also demonstrate the practical advantages of efficient protection by the SSAG surrounding the protein crystals. (C) 2011 The Japan Society of Applied Physics
• Gradual Immobilization Processes of Molecules during Transitions from Solute to Solid States

  Guoliang Dai, Gen Sazaki, Takuro Matsui, Katsuo Tsukamoto, Kazuo Nakajima, Qi Kang, Wenrui Hu

  CRYSTAL GROWTH & DESIGN 11 (1) 88 - 92 1528-7483 2011/01 [Refereed][Not invited]
   

  The adsorption/desorption behavior of mobile solute molecules at a solution-crystal interface has been explored using crystals of model protein hen egg-white lysozyme (HEWL) and fluorescent-labeled HEWL (F-HEWL) molecules. We have tracked the transient processes occurring during adsorption/desorption of identical F-HEWL molecules on a tetragonal HEWL crystal surface by single-molecule visualization using a total internal reflection fluorescent microscope and pulsed discontinuous laser illumination. We found an induction period (similar to 70 min) after which the number density of F-HEWL molecules adsorbed mainly on steps increased linearly with the adsorption time. We show direct evidence that the residence time of molecules on the crystal surface gradually increases during the transition process from a solute species to the crystal after successive multistep processes.
• Elementary steps at the surface of ice crystals visualized by advanced optical microscopy

  Gen Sazaki, Salvador Zepeda, Shunichi Nakatsubo, Etsuro Yokoyama, Yoshinori Furukawa

  PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 107 (46) 19702 - 19707 0027-8424 2010/11 [Refereed][Not invited]
   

  Due to the abundance of ice on earth, the phase transition of ice plays crucially important roles in various phenomena in nature. Hence, the molecular-level understanding of ice crystal surfaces holds the key to unlocking the secrets of a number of fields. In this study we demonstrate, by laser confocal microscopy combined with differential interference contrast microscopy, that elementary steps (the growing ends of ubiquitous molecular layers with the minimum height) of ice crystals and their dynamic behavior can be visualized directly at air-ice interfaces. We observed the appearance and lateral growth of two-dimensional islands on ice crystal surfaces. When the steps of neighboring two-dimensional islands coalesced, the contrast of the steps always disappeared completely. We were able to discount the occurrence of steps too small to detect directly because we never observed the associated phenomena that would indicate their presence. In addition, classical two-dimensional nucleation theory does not support the appearance of multilayered two-dimensional islands. Hence, we concluded that two-dimensional islands with elementary height (0.37 and 0.39 nm on basal and prism faces, respectively) were visualized by our optical microscopy. On basal and prism faces, we also observed the spiral growth steps generated by screw dislocations. The distance between adjacent spiral steps on a prism face was about 1/20 of that on a basal face. Hence, the step ledge energy of a prism face was 1/20 of that on a basal face, in accord with the known lower-temperature roughening transition of the prism face.
• In Situ Observation of Step Dynamics on Gypsum Crystals

  Alexander E. S. Van Driessche, Juan Manuel Garcia-Ruiz, Jose Manuel Delgado-Lopez, Gen Sazaki

  CRYSTAL GROWTH & DESIGN 10 (9) 3909 - 3916 1528-7483 2010/09 [Refereed][Not invited]
   

  In this work we studied the kinetics of gypsum crystals growing from aqueous solutions as a function of temperature and supersaturation. Laser confocal differential interference contrast microscopy (LCM-DIM) and atomic force microscopy (A FM) were used to observe in situ the step advancement and the evolution of the surface morphology of the {010} face. We found that, for the experimental conditions used in this study, 2D nucleation is the main step generation mechanism, even at low supersaturations, and only a few spiral hillocks were observed. Due to the elongated morphology of 2D islands along the c-axis and the frequent nucleation of multilayer 2D islands, {010} faces growing from a supersatured solution developed a "hill and valley" topography. This type of surface topography is observed at all temperatures. The step kinetic coefficient, beta(st), was determined in the temperature range 20-80 degrees C, and a steep increment in the kinetic coefficient is found with increasing temperature. From these data, the activation barrier for incorporation of building units in the (010) face was determined to be 70.7 +/- 5.0 kJ/mol. Analysis of the kinetic data shows that at low temperatures (<= 40 degrees C) growth of the {010) face is dominated by a mixed regime and at higher temperatures (>40 degrees C) growth is controlled solely by diffusion.
• First Direct Observation of Elementary Steps on the Surfaces of Glucose Isomerase Crystals under High Pressure (vol 9, pg 4289, 2009)

  Yoshihisa Suzuki, Gen Sazaki, Masamitsu Matsumoto, Makoto Nagasawa, Kazuo Nakajima, Katsuhiro Tamura

  CRYSTAL GROWTH & DESIGN 10 (4) 2020 - 2020 1528-7483 2010/04 [Refereed][Not invited]
  
• An Approach to DNA Crystallization Using the Thermal Reversible Process of DNA Duplexes

  Toshiyuki Chatake, Gen Sazaki, Tatsuhiko Kikkou, Satoru Fujiwara, Takuya Ishikawa, Osamu Matsumoto, Yukio Morimoto

  CRYSTAL GROWTH & DESIGN 10 (3) 1090 - 1095 1528-7483 2010/03 [Refereed][Not invited]
   

  We propose a technique for DNA crystallization using the thermal reversible process of DNA. A double-stranded DNA (dsDNA) can be converted into two single-stranded DNAs (ssDNAs) at high temperatures to improve its water solubility. Thus, this thermal conversion can be utilized for increasing the solubility of DNA crystals by changing solute species. We investigated the solubility of the crystals of a DNA hexamer d(CGCGCG) and their melting temperature, at which thermal conversion occurs from it dsDNA to ssDNAs or vice versa. A van't Hoff plot showed two crystallization processes with it change in temperature dependency of the solubility at around 315 K. This result almost corresponded to the melting temperature (322 K) measured by UV spectroscopy. These Findings suggest that the conversion from a dsDNA to ssDNAs results in an increase in solubility. Using this temperature-controlled technique, single crystals of the DNA hexamer could be obtained from a small amount of DNA samples; X-ray assessment demonstrated that these crystals were high grade. This easy-to-apply technique would be superior to the conventional vapor diffusion technique in that it allows the solubility of DNA crystals to be controlled with no need for expensive Setups.
• Nucleation and Polymorphism of Calcium Carbonate by a Vapor Diffusion Sitting Drop Crystallization Technique

  Jaime Gomez-Morales, Angeles Hernandez-Hernandez, Gen Sazaki, Juan Manuel Garcia-Ruiz

  CRYSTAL GROWTH & DESIGN 10 (2) 963 - 969 1528-7483 2010/02 [Refereed][Not invited]
   

  The nucleation and polymorphism of calcium carbonate have been studied using a microdevice named the crystallization mushroom. This setup allows carrying out precipitation experiments reproducibly by the vapor diffusion sitting drop technique. Within the range of concentrations investigated (from 10 to 500 mmol/L CaCl(2) and from 1 to 25 mmol/L NH(4)HCO(3)), the dominant polymorph to appear first in the drops wits calcite, or mixtures of calcite and vaterite followed by aragonite. Additionally, amorphous calcium carbonate (ACC) was not observed. The order of appearance of the polymorphs in the droplets is explained by intrinsic features of the crystallization mushroom, that is, the slow increase in the ionic activity product caused by slow diffusion of NH(3) and CO(2) gases, which favors the least soluble phase calcite to crystallize before other more soluble polymorphs. The appearance of calcite its the first nucleating dominant polymorph in the drops allowed us to calculate its surface free energy from induction time measurements assuming the mononuclear nucleation model. The experimentally calculated result of 35 mJ/m(2) is lower than the value predicted for homogeneous nucleation. The cause is the existence of heterogeneous nucleation taking place at the air-solution and solution-support interfaces.
• 1SC1105 Micro-structure formation and its effect on molecular diffusion in supported lipid bilayer membranes(1SC Fluctuation and Function of Biomolecules,The 48th Annual Meeting of the Biophysical Society of Japan)

  Tero Ryugo, Sazaki Gen, Ujihara Toru, Urisu Tsuneo

  Seibutsu Butsuri 一般社団法人 日本生物物理学会 50 (2) S2 - S3 2010
• Enhancement of femtosecond laser-induced nucleation of protein in a gel solution

  Ryota Murai, Hiroshi Y. Yoshikawa, Yoshinori Takahashi, Mihoko Maruyama, Shigeru Sugiyama, Gen Sazaki, Hiroaki Adachi, Kazufumi Takano, Hiroyoshi Matsumura, Satoshi Murakami, Tsuyoshi Inoue, Yusuke Mori

  APPLIED PHYSICS LETTERS 96 (4) 0003-6951 2010/01 [Refereed][Not invited]
   

  We found that the use of a gel solution with agarose enhanced femtosecond laser-induced nucleation and produced hen egg white lysozyme crystals at three to five times lower supersaturation than those by the femtosecond laser or agarose alone. The fast fluorescence imaging of the protein in the gel solution revealed that cavitation bubbles created high-concentration regions at the focal point, which could be the trigger for protein nucleation. The lower diffusions of protein molecules in agarose gel retained the high-concentration regions for a longer time, and facilitated the nucleation.
• Solubility measurements of protein crystals under high pressure by in situ observation of steps on crystal surfaces

  T. Fujiwara, Y. Suzuki, G. Sazaki, K. Tamura

  INTERNATIONAL CONFERENCE ON HIGH PRESSURE SCIENCE AND TECHNOLOGY, JOINT AIRAPT-22 AND HPCJ-50 215 1742-6588 2010 [Refereed][Not invited]
   

  We successfully measured equilibrium temperatures T(e) of tetragonal hen egg-white lysozyme crystals under high pressure by in situ observation of steps on the {110} faces of the crystals. The dependence of T(e) on the concentration of lysozyme corresponds to that of the solubility C(e) on temperature. The precision of the solubility determined in this study is significantly higher than that in previous works. One T(e) could be measured during short time less than 70 minutes. This method for solubility measurements of protein crystals under high pressure is the fastest one at this stage.
• Crystal quality enhancement by magnetic fields

  Gen Sazaki

  PROGRESS IN BIOPHYSICS & MOLECULAR BIOLOGY 101 (1-3) 45 - 55 0079-6107 2009/11 [Refereed][Not invited]
   

  From the latter half of the 90s, many studies of the effects of magnetic fields on protein crystallization have been carried out. It has been found that the crystallization of proteins under both homogeneous and inhomogeneous (gradient) magnetic fields enhances the quality of protein crystals. The quality enhancement is attributed to the magnetic orientation of protein crystals and the magnetic suppression of buoyancy convection in protein solutions. The magnetic fields also affect the kinetics of protein crystallization and hence change the habit of protein crystals. In this review, the effects of magnetic fields on protein crystallization, their mechanisms and indispensable future studies are outlined. (C) 2009 Elsevier Ltd. All rights reserved.
• First Direct Observation of Elementary Steps on the Surfaces of Glucose Isomerase Crystals under High Pressure

  Yoshihisa Suzuki, Gen Sazaki, Masamitsu Matsumoto, Makoto Nagasawa, Kazuo Nakajima, Katsuhiro Tamura

  CRYSTAL GROWTH & DESIGN 9 (10) 4289 - 4295 1528-7483 2009/10 [Refereed][Not invited]
   

  We have succeeded in the first direct observation under high pressure of the elementary steps (7.2 nm high) on {011} faces of glucose isomerase (GI) crystals, by using a laser confocal microscope combined with a differential interference contrast microscope (LCM-DIM) and a specially designed high-pressure vessel with a sapphire window of 1 mm thickness. The images of elementary steps taken under 50 MPa exhibited a sufficiently high contrast level for subsequent studies of crystal growth. By in situ observations, we directly confirmed that, irrespective of pressure, {011} faces of GI crystals grew by two-dimensional (2D) nucleation growth of the polynucleation type, and that pressure did not affect growth morphology. We measured the solubility of GI crystals under high pressure by observing in situ the growth and dissolution of elementary steps and ridges on the crystals. The resulting solubility curve exhibited much higher precision than those determined by interferometry, and revealed a significant decrease in solubility with increasing pressure. We also measured the 2D nucleation rates of 2D islands and the velocities of elementary steps under high pressure.
• Direct Observation of Adsorption Sites of Protein Impurities and Their Effects on Step Advancement of Protein Crystals

  Alexander E. S. Van Driessche, Gen Sazaki, Guoliang Dai, Fermin Otalora, Jose A. Gavira, Takuro Matsui, Izumi Yoshizaki, Katsuo Tsukamoto, Kazuo Nakajima

  CRYSTAL GROWTH & DESIGN 9 (7) 3062 - 3071 1528-7483 2009/07 [Refereed][Not invited]
   

  We measured noninvasively step velocities of elementary two-dimensional (2D) islands on {110} faces of tetragonal lysozyme crystals, under various supersaturations, by laser confocal microscopy combined with differential interference contrast microscopy. We studied the correlation between the effects of protein impurities on the growth of elementary steps and their adsorption sites on a crystal surface, using three kinds of proteins: fluorescent-labeled lysozyme (F-lysozyme), covalently bonded dimers of lysozyme (dimer), and a 18 kDa polypeptide (18 kDa). These three protein impurities suppressed the advancement of the steps. However, they exhibited different supersaturation dependencies of the Suppression of the step velocities. To clarify the cause of this difference, we observed in situ the adsorption sites of individual molecules of F-lysozyme and fluorescent-labeled dimer (F-dimer) on the crystal surface by single-molecule visualization. We found that F-lysozyme adsorbed preferentially on steps (i.e., kinks), whereas F-dimer adsorbed randomly on terraces. Taking into account the different adsorption sites of F-lysozyme and F-dimer, we could successfully explain the different effects of the impurities on the step velocities. These observations strongly suggest that 18 kDa also adsorbs randomly on terraces. Seikagaku lysozyme exhibited a complex effect that could not alone be explained by the two major impurities (dimer and 18 kDa) present in Seikagaku lysozyme, indicating that trace amounts of other impurities significantly affect the step advancement.
• Chiral and Achiral Mechanisms of Regulation of Calcite Crystallization

  Mihoko Maruyama, Katsuo Tsukamoto, Gen Sazaki, Yoshihiro Nishimura, Peter G. Vekilov

  CRYSTAL GROWTH & DESIGN 9 (1) 127 - 135 1528-7483 2009/01 [Refereed][Not invited]
   

  The regulation of calcite mineralization by chiral biological molecules is one of the fundamental unresolved issues at the interface between biological, geological, and physical sciences. Here we address the role of chirality of L-aspartic acid (L-Asp), a model additive, in the regulation of the growth of calcite crystals. We apply phase-shift interferometry to nonintrusively monitor in-situ the morphology of the surface and quantify the velocity of propagation of the edges of the unfinished crystal layers, the steps, during crystallization. We show that L-Asp leads to several-fold increase in the step velocity, in all directions, at low supersaturations, and several-fold decrease in the step velocity at high supersaturations. L-Asp also introduces asymmetry in the velocity of steps related by mirror symmetry, however, of <= 10%. To explain the complex effects of L-Asp and, likely, of other biological regulators of calcite crystallization, we show that prior to incorporation into steps, calcium and carbonate ions adsorb on the terraces and diffuse toward the steps. L-Asp accelerates the surface diffusion toward the steps, an achiral process, likely because of rearrangement by L-Asp of the structure of the water coating the calcite crystal surface. Importantly, L-Asp delays by similar to 20x the incorporation of calcite ions into the steps, the only chiral process in the calcite crystallization mechanism, likely by blocking a significant fraction of the kinks. We show that the low asymmetry between the two chiral directions is due to suppression of chirality by the symmetric surface supply fields of the steps. The results and analyses presented here suggest that the chiral effects of biogenerated molecules on crystallization may be too weak to determine the biological or nonbiological origin of minerals.
• Influence of micro-impurity on protein crystal growth studied by the etch figure method

  Guoliang Dai, Xingyu Liu, Gen Sazaki, Xiaogang Zhang

  JOURNAL OF CRYSTAL GROWTH 311 (3) 548 - 552 0022-0248 2009/01 [Refereed][Not invited]
   

  The investigation of the effect of micro impurity on crystal growth by optical microscopy has been validated. The results showed that the growth rate of a lysozyme crystal was affected even if the concentration of impurity of fluorescent-labeled lysozyme (abbreviation, F-lysozyme) was very small. Different concentrations of F-lysozyme had different effects on crystal growth rate. The growth rate decreased much more as F-lysozyme concentration increased. The density of incorporated F-lysozyme on different grown layers of a lysozyme crystal during crystal growth was obtained from the results of flat-bottomed etch pits density. (C) 2008 Elsevier B.V. All rights reserved.
• Femtosecond laser-induced nucleation of protein in agarose gel

  Hiroshi Y. Yoshikawa, Ryota Murai, Shigeru Sugiyama, Gen Sazaki, Tornoya Kitatani, Yoshinori Takahashi, Hiroaki Adachi, Hiroyoshi Matsumura, Satoshi Murakami, Tsuyoshi Inoue, Kazufumi Takano, Yusuke Mori

  JOURNAL OF CRYSTAL GROWTH 311 (3) 956 - 959 0022-0248 2009/01 [Refereed][Not invited]
   

  We have performed femtosecond laser-induced nucleation of protein in agarose gel to study the crystallization dynamics. The use of agarose gel facilitates the monitoring of laser-induced crystallization from the focal point, because the gel forms a highly viscous solution at low supersaturation and thereby suppresses the diffusion of laser-induced bubbles and microcrystals. We succeeded in monitoring the crystallization process from the focal point in the time range from microseconds to days. In addition, by combining an agarose gel system with fluorescence imaging, we revealed that the shrinking of laser-induced cavitation bubbles causes a local increase of protein concentration, which could be the trigger for protein nucleation. (c) 2008 Elsevier B.V. All rights reserved.
• The adsorption of protein molecules at a crystal/solution interface observed by an improved TIRFM

  Guoliang Dai, Gen Sazaki

  2009 3RD INTERNATIONAL CONFERENCE ON BIOINFORMATICS AND BIOMEDICAL ENGINEERING, VOLS 1-11 2382 - + 2009 [Refereed][Not invited]
   

  We have improved the ordinary total internal reflection fluorescence microscopy (TIRFM). Two improvements have been achieved, one is the interface between opaque material and solution can be observed, another is the interface far away (usually several ten micro meters) the objective lens can be observed. By this improved TIRFM, the adsorption of protein molecules at a crystal/solution interface had been successfully observed. We have obtained the results of relationship between the amount of adsorbed protein molecules on bunched steps and the height of bunched steps of a protein crystal.
• Comparison of Different Experimental Techniques for the Measurement of Crystal Growth Kinetics

  Alexander E. S. Van Driessche, Fermin Otalora, Gen Sazaki, Mike Sleutel, K. Tsukamoto, Jose A. Gavira

  CRYSTAL GROWTH & DESIGN 8 (12) 4316 - 4323 1528-7483 2008/12 [Refereed][Not invited]
   

  The relative merits and domains of application of three observation techniques (atomic force microscopy, Michelson interferometry, and laser confocal microscopy with differential interference contrast microscopy) for the investigation of crystal growth kinetics are discussed in the context of protein crystallization. Growth rate measurements on the same system under identical experimental conditions using different techniques show differences up to 5-fold in growth rate and a different behavior of growth rate as a function of supersaturation. These results are discussed in terms of differences in mass transport at the crystal interface during data collection in the first case and as data processing artifacts in the second. Guidelines are provided for the selection of the optimal observation technique in crystal growth studies as a function of the specific problem under investigation, showing that AFM is best suited for nanometere-size, slow processes; LCM-DIM for nanometer-micrometer size, slow and medium processes; and PSMI for micrometer size, fast processes.
• Laser energy dependence on femtosecond laser-induced nucleation of protein

  Hiroshi Y. Yoshikawa, Ryota Murai, Syou Maki, Tomoya Kitatani, Shigeru Sugiyama, Gen Sazaki, Hiroaki Adachi, Tsuyoshi Inoue, Hiroyoshi Matsumura, Kazufumi Takano, Satoshi Murakami, Takatomo Sasaki, Yusuke Mori

  APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING 93 (4) 911 - 915 0947-8396 2008/12 [Refereed][Not invited]
   

  We have investigated femtosecond laser-induced nucleation of hen egg-white lysozyme (HEWL) as a function of the laser pulse energy and pulse time width. This is the first recorded study to confirm that the femtosecond laser-induced nucleation of HEWL can be induced at a specific threshold laser energy. The threshold energy is comparable to that of cavitation bubble generation. The results strongly suggest that morphological changes in the solution are key factors for protein nucleation.
• Is agarose an impurity or an impurity filter? In situ observation of the joint gel/impurity effect on protein crystal growth kinetics

  Alexander E. S. Van Driessche, Fermin Otalora, Jose A. Gavira, Gen Sazaki

  CRYSTAL GROWTH & DESIGN 8 (10) 3623 - 3629 1528-7483 2008/10 [Refereed][Not invited]
   

  The joint effect of agarose gel and impurities on hen egg white lysozyme crystal growth kinetics was investigated in situ by comparing the two-dimensional (2D) nucleation rate and the step velocity of crystals growing from free and gelled (agarose) solutions having two different levels of purity: highly purified (99.99% pure) and commercial grade (98.5% pure). The 2D nucleation rate and step velocity were measured on {110} faces of tetragonal lysozyme crystals using laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM). 2D nucleation rates are enhanced by the presence of gel fibers that act as heterogeneous nucleation sites. These results also show that the specific surface energies are similar for the gel fiber/crystal interface and for the gel fiber/solution interface. This is consistent with the observed incorporation of agarose fibers into the lysozyme crystal lattice and the small effect of gel fibers on step velocity. 2D nucleation in the presence of both gel and impurities is also enhanced but not as much as for gelled purified solutions. The presence of agarose has an almost negligible effect on the step velocity in purified solutions but significantly modifies the step velocity in crystals growing from impure solutions, shifting these values closer to the velocities measured in purified solutions. This velocity increase corresponds to a 7-fold reduction in the concentration of adsorbed impurities at the crystal surface with respect to ungelled experiments. This direct evidence of the diffusive impurity filtering concept is also consistent with the qualitative observations on 2D island morphologies.
• Single-molecule visualization of diffusion at the solution - Crystal interface

  Gen Sazaki, Masashi Okada, Takuro Matsui, Tomonobu Watanabe, Hideo Higuchi, Katsuo Tsukamoto, Kazuo Nakajima

  CRYSTAL GROWTH & DESIGN 8 (6) 2024 - 2031 1528-7483 2008/06 [Refereed][Not invited]
   

  We directly observed the diffusion of individual fluorescence-labeled protein molecules at an interface between a solution and a protein crystal using a single-molecule visualization technique, by which we can observe individual molecules with fluorescence labels. We simulated the diffusion behavior of mobile solute molecules at a solution-crystal interface, using fluorescence-labeled lysozyme and tetragonal lysozyme crystals. We found that the molecules diffused along the crystal surface 4-5 orders of magnitude slower (diffusion coefficient (6.9 +/- 1.2) x 10(-15) m(2)/S) than in a bulk solution, indicating that the molecules strongly interacted with molecules that were aligned at the crystal surface. This result denotes that slow two-dimensional diffusion inside a range of interactions from the crystal surface is a general picture of surface diffusion at an interface between an aqueous solution and a hydrophilic crystal surface. In addition, the number density of the molecules at the interface was 3 orders of magnitude higher than that estimated from a concentration of a bulk solution, demonstrating that interaction from the crystal surface drastically condensed the molecules at the interface. The average residence time and average diffusion length of the molecules at the interface were 0.47 s and 0.11 mu m, respectively.
• In situ observation of Si faceted dendrite growth from low-degree-of-undercooling melts

  Kozo Fujiwara, Kensaku Maeda, Noritaka Usami, Gen Sazaki, Yoshitaro Nose, Akiko Nomura, Toetsu Shishido, Kazuo Nakajima

  ACTA MATERIALIA 56 (11) 2663 - 2668 1359-6454 2008/06 [Refereed][Not invited]
   

  We directly observed the transition of crystal growth behavior of Si in a low undercooling region. We succeeded in observing the initiation of faceted dendrite growth from a portion of parallel twins with increasing degrees of undercooling. The critical undercooling for growing a faceted dendrite was experimentally determined to be Delta T= 10 K. We also confirmed that parallel twins associated with faceted dendrite growth were formed between grain boundaries and not at grain boundaries during melt growth. The parallel-twin formation was explained in terms of a model of twin formation on the {111} facet plane at the growth interface. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
• Single-molecule measurements and dynamical simulations of protein molecules near silicon substrates

  Itsuo Hanasaki, Hiroto Takahashi, Gen Sazaki, Kazuo Nakajima, Satoyuki Kawano

  JOURNAL OF PHYSICS D-APPLIED PHYSICS 41 (9) 0022-3727 2008/05 [Refereed][Not invited]
   

  Interactions between protein molecules and inorganic substrates were studied both experimentally and numerically to obtain fundamental insight into the assembly of biomacromolecules for engineering applications. We experimentally traced individual fluorescent-labelled lysozyme (F-lysozyme) molecules, diffusing in the vicinity of interfaces between a protein solution and oxidized Si( 1 0 0) and glass plates. The results indicate that diffusion coefficients of F-lysozyme molecules on both substrates are more than three orders of magnitude smaller than those in a bulk solution. The molecular dynamics simulations reveal a drastically diminished diffusion coefficient of lysozyme on the substrates of pure Si( 1 1 1) and oxidized Si( 1 0 0) with a hydroxy-terminated surface compared with that in bulk solution due to molecular adsorption behaviour on the substrate, which is in good agreement with experimental results. Furthermore, full atomistic description of the behaviour provides detailed information of deformation due to the adsorption process. Lysozyme on pure Si( 1 1 1) undergoes substantial deformation whereas that on oxidized Si( 1 0 0) does not, which indicates the importance of substrate surface condition to preserve the structure, i.e. functionality of adsorbed biomolecules.
• Two Epitaxal Structures of Pentacene Polycrystalline Thin Films Crystals on a Hydrogen Terminated Si(111)

  S. Nishikata, G. Sazaki, J.T. Sadowski, A.Al-Mahboob, T. Nishihara, S. Suto, T. Sakurai, K. Nakajima

  Phys. Rev. B 76 165424-1 - 10 2007/11/15 [Refereed][Not invited]
  
• Polycrystalline domain structure of pentacene thin films epitaxially grown on a hydrogen-terminated Si(111) surface

  S. Nishikata, G. Sazaki, J. T. Sadowski, A. Al-Mahboob, T. Nishihara, Y. Fujikawa, S. Suto, T. Sakurai, K. Nakajima

  PHYSICAL REVIEW B 76 (16) 1098-0121 2007/10 [Refereed][Not invited]
   

  Single-monolayer high pentacene (Pn) dendrites grown on a hydrogen-terminated Si(111) surface [H-Si(111)] under ultrahigh vacuum were observed by low-energy electron microscopy and microbeam low-energy electron diffraction analyses. We determined the epitaxial structure (type I) inside a unique polycrystalline domain structure of such dendrites, each of which has six equivalent epitaxial orientations of Pn two-dimensional (2D) unit cells. There are three sets of these cells, which are rotated +/- 120 degrees relative to each other. Domain boundaries inside each dendrite were successfully observed by scanning tunneling microscopy. In addition, we found another epitaxial relation (type II): the polycrystalline domain structure and lattice parameters are similar to those of the type-I dendrite; however, the 2D unit cells of the type-II dendrite are rotated approximately 90 degrees relative to those of the type-I dendrite. These results suggest that the crystal structure of the dendrites on H-Si(111) is determined mainly by the interaction between Pn molecules. Each dendrite is composed of domains that are exclusively of type I or II. The so-called point-on-line coincidences are found between the Pn 2D lattices of types I and II, and H-Si(111). The higher commensurability of the type-I dendrites than the type-II dendrites results in a higher probability of type-I dendrite formation. Moreover, for both the type-I and type-II dendrites, we found supercell structures. We estimated the minimum interface energy between the dendrite and H-Si(111) from an island's free energy, which is necessary to reproduce the growth of a single-monolayer high dendrite.
• Direct and noninvasive observation of two-dimensional nucleation behavior of protein crystals by advanced optical microscopy

  Alexander E. S. Van Driessche, Gen Sazaki, Fermin Otalora, Francisco M. Gonzalez-Rico, Peter Dold, Katsuo Tsukamoto, Kazuo Nakajima

  CRYSTAL GROWTH & DESIGN 7 (10) 1980 - 1987 1528-7483 2007/10 [Refereed][Not invited]
   

  We observed two-dimensional (2D) nucleation behavior on {110} and {101} faces of tetragonal crystals of model protein lysozyme by laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM). We measured, for the first time directly and noninvasively, the 2D nucleation rates using 99.99% pure lysozyme, 98.5% pure lysozyme (Seikagaku Co.), and 99.99% pure lysozyme with intentionally added impure proteins (fluorescent-labeled lysozyme, covalently bonded dimer of lysozyme, and IS kDa polypeptide). We found that 2D nucleation was the dominant growth mechanism under conditions adopted in this study, and the 2D nucleation occurred randomly on the entire crystal surface irrespective of supersaturation within the range of sigma = ln(C/C-e) = 0-1.4, where C is a bulk lysozyme concentration and C, the solubility (crystal size: 0.2-0.3 mm). Repeated 2D nucleation, which continued for 3-4 layers, was also observed mainly when the impure proteins were present. In addition, multilayered 2D islands were formed after the adsorption of relatively large foreign particles on the crystal surface. From the comparison between the 2D nucleation rates determined on the {110} faces with and without the impure proteins, we concluded that homogeneous 2D nucleation occurred under a higher supersaturation range (sigma > 0.8), irrespective of the presence of the impurities. In contrast, under a lower supersaturation range (sigma < 0.8), we found that significant heterogeneous 2D nucleation dominated the growth mainly when the impure proteins were present. The {101} faces exhibited more significant heterogeneous 2D nucleation induced by smaller amounts of impurities than in the case of the {110} faces. We also determined the ledge free energies of the homogeneous and heterogeneous nucleation. Within the experimental conditions used in this study, we could not find significant dependence of the ledge free energies of the heterogeneous nucleation on the kinds of impure proteins.
• Preparation of an ultraclean and atomically controlled hydrogen-terminated si(111)-(1x1) surface revealed by high resolution electron energy loss spectroscopy, atomic force microscopy, and scanning Tunneling microscopy: Aqueous NH4F etching process of si(111)

  Hiroki Kato, Takumi Taoka, Susumu Nishikata, Gen Sazaki, Taro Yamada, Ryszard Czajka, Andrzej Wawro, Kazuo Nakajima, Atsuo Kasuya, Shozo Suto

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS 46 (9A) 5701 - 5705 0021-4922 2007/09 [Refereed][Not invited]
   

  We propose an improved wet chemical process for preparing a high-quality hydrogen-terminated Si(111)-(1 x 1) surface and show an atomically ordered and ultraclean surface without carbon and oxygen contamination. The vibrational properties and surface morphology are investigated by high-resolution electron energy loss spectroscopy (HREELS), atomic force microscopy (AFM), and scanning tunneling microscopy (STM). The HREELS spectra and images of AFM and STM reveal the precise aqueous NH4F etching process of Si(111) and indicate the high controllability of steps and terraces at the atomic scale. The surface cleanliness and morphology strongly depend on the etching time. At the etching time of 10 min, we obtain an ultraclean and atomically ordered surface with wide terraces of 36 +/- 17 nm step distance. It is confirmed by AFM and STM that 1.0% ammonium sulfite is useful for removing dissolved oxygen in the 40% NH4F etching solution and for preparing a high-quality H:Si(I I I)-(I x 1) surface with a low density of etch pits. The onset of tunneling current and the gap of 1.39 eV are measured by scanning tunneling spectroscopy. There is no peak at -1.3 eV in comparison with the previous report.
• Surface-enhanced hyper-Raman spectroscopy using optical trapping of silver nanoparticles for molecular detection in solution

  H. Yoshikawa, T. Adachi, G. Sazaki, T. Mastui, K. Nakajima, H. Masuhara

  JOURNAL OF OPTICS A-PURE AND APPLIED OPTICS 9 (8) S164 - S171 1464-4258 2007/08 [Refereed][Not invited]
   

  Optical trapping of silver nanoparticles dispersed with rhodamine 6G (R6G) and NaCl in water gives surface-enhanced hyper-Raman scattering (SEHRS) of R6G. In this paper we have measured the SEHRS spectrum in the R6G concentration range between 10(-7) and 10(-11) M. SEHRS intensity and signal-to-noise ratio show clear differences at the lower R6G concentrations than similar to 10(-9) M, indicating that the number of R6G in a trapped silver aggregate approaches the single-molecule level. This trapping SEHRS technique is applied for the detection of lysozyme molecules labelled with tetramethylrhodamine dye.
• Formation mechanism of parallel twins related to Si-facetted dendrite growth

  K. Fujiwara, K. Maeda, N. Usami, G. Sazaki, Y. Nose, K. Nakajima

  SCRIPTA MATERIALIA 57 (2) 81 - 84 1359-6462 2007/07 [Refereed][Not invited]
   

  We propose a simple model to explain formation mechanism of parallel twins that are related to Si-facetted dendrite growth, and attempt to confirm its validity by in situ observations. The model involves the formation of a twin boundary at the {1 111 facet plane on the growth interface followed by formation of another twin parallel to the first one. Subsequently, a facetted dendrite grows parallel to the facet plane in this model. This growth behavior was successfully observed by growth experiments. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
• Detection of covalent-bonded dimer in photochemically induced crystallization of protein

  Kenji Furuta, Tetsuo Okutsu, Gen Sazaki, Izumi Yoshizaki, Hiroaki Horiuchi, Tetsuya Shimizu, Masaki Yamamoto, Yoshihito Tanaka, Hiroshi Hiratsuka

  CHEMISTRY LETTERS 36 (6) 714 - 715 0366-7022 2007/06 [Refereed][Not invited]
   

  We investigate light-induced crystallization mechanism of hen egg-white lysozyme. Photochemical intermediate radical has been expected to form cluster which grows to nucleus. To confirm the nucleation process that the radical grows to the crystal, SDS-PAGE, crystallization experiments were carried out. Covalent-bonded dimer was produced by photochemical reaction, and it grows to the crystal. We conclude that the dimer plays the role of the smallest stable cluster in early stage of the crystallization process.
• Step-induced anisotropic growth of pentacene thin film crystals on a hydrogen-terminated Si(111) surface

  Susumu Nishikata, Gen Sazaki, Toshihiko Takeuchi, Noritaka Usami, Shozo Suto, Kazuo Nakajima

  CRYSTAL GROWTH & DESIGN 7 (2) 439 - 444 1528-7483 2007/02 [Refereed][Not invited]
   

  We investigate thin film crystals of an organic semiconductor, pentacene (Pn), grown on hydrogen-terminated Si(111) (H-Si(111)) surfaces with various interstep distances to elucidate the effects of vicinal steps of H-Si(111) on the growth of the Pn layers. By observing the morphology of the thin films with atomic force microscopy, we conclude that the vicinal steps induce significant anisotropy in the growth of the first layers of Pn: dendritic branches evolve in a lower-terrace side (the Si[11 (2) over bar] direction), but a compact shape appears in an upper-terrace side (the Si[(1) over bar(1) over bar2] direction), although the first layers grow in an isotropic shape on a flat H-Si(111) surface. Furthermore, the growth of the first layers is much faster in the lower-terrace-side direction than in the upper-terrace-side direction. The anisotropy of the growth increases with decreasing interstep distances of H-Si(111), in particular <= 10 nm. Since such anisotropic growth was observed in a similar way irrespective of the directions of an incident Pn molecular beam, we conclude that the cause of the anisotropic growth is not the anisotropy of the surface diffusion and admolecule distribution of Pn molecules. Under the substrate temperature of 30-90 degrees C, the degree of the anisotropy remained constant within experimental error.
• 2P243 Direct microscopic observation of biomembrane dynamics under a static magnetic field(Native and artificial biomembranes-structure and properties,Poster Presentations)

  Tamatsukuri Kouya, Ohba Tetsuhiko, Sazaki Gen, Ohki Kazuo

  Seibutsu Butsuri 一般社団法人 日本生物物理学会 47 S173  2007
• Single-nucleus polycrystallization in thin film epitaxial growth

  J. T. Sadowski, G. Sazaki, S. Nishikata, A. Al-Mahboob, Y. Fujikawa, K. Nakajima, R. M. Tromp, T. Sakurai

  PHYSICAL REVIEW LETTERS 98 (4) 0031-9007 2007/01 [Refereed][Not invited]
   

  We have observed, by use of low-energy electron microscopy, the first direct evidence of self-driven polycrystallization evolved from a single nucleus in the case of epitaxial pentacene growth on the Si(111)-H terminated surface. In this Letter we demonstrate that such polycrystallization can develop in anisotropic systems (in terms of crystal structure and/or the intermolecular interactions) when kinetic growth conditions force the alignment of the intrinsic preferential growth directions along the density gradient of diffusing molecules. This finding gives new insight into the crystallization of complex molecular systems, elucidating the importance of nanoscale control of the growth conditions.
• Impurity effects of lysozyme molecules specifically labeled with a fluorescent reagent on the crystallization of tetragonal and monoclinic lysozyme crystals

  Takuro Matsui, Gen Sazaki, Hironori Hondoh, Yoshiki Matsuura, Toshitaka Nakada, Kazuo Nakajima

  JOURNAL OF CRYSTAL GROWTH 293 (2) 415 - 422 0022-0248 2006/08 [Refereed][Not invited]
   

  To study the effects of impure proteins, i.e. proteins with heterogeneous features that are minor constituents within "purified" protein solutions, on the crystallization of target proteins, and in particular the effects of such impurities on intermolecular contacts, we modified only the e-amino group of the N-terminal lysine of hen egg-white lysozyme with a fluorescent reagent, tetramethylrhodamine-5-isothiocyanate (5-TRITC), which has a high detection sensitivity. We then investigated the effects of the fluorescent-labeled lysozyme (Flysozyme) on the nucleation and growth of tetragonal and monoclinic lysozyme crystals. In the tetragonal and monoclinic crystals, the fluorescent labels were located at molecular surfaces of lysozyme inside and outside of the intermolecular contact areas, respectively. We found that addition of a low concentration (0.02 mg/ml) of F-lysozyme significantly suppressed nucleation of the tetragonal crystals but had no effect on that of the monoclinic crystals. In contrast, addition of a higher concentration (0.05 mg/ml) of F-lysozyme significantly promoted the heterogeneous nucleation of both polymorphs. In addition, the decrease in the growth rate of the tetragonal crystal by Flysozyme was much more significant than that of the monoclinic one, although the effective distribution coefficients of F-lysozyme for the tetragonal and monoclinic crystals were similar (2.9 and 3.2, respectively). These results clearly indicate that inhibiting the formation of specific intermolecular contacts plays a crucial role in the effects of impure proteins. (c) 2006 Elsevier B.V. All rights reserved.
• Step velocity in tetragonal lysozyme growth as a function of impurity concentration and mass transport conditions

  P. Dold, E. Ono, K. Tsukamoto, G. Sazaki

  JOURNAL OF CRYSTAL GROWTH 293 (1) 102 - 109 0022-0248 2006/07 [Refereed][Not invited]
   

  The step velocity on {110} faces of tetragonal lysozyme crystals has been measured in situ by high-resolution phase contrast microscopy. The movement of the steps shows a distinct anisotropy with respect to the growth velocity and the interaction with impurities. Under high-purity conditions (using lysozyme of 99.99% purity), the step velocity nu(step) in the < 110 > direction exceeds the one in the < 001 > direction by a factor of 6. Spiral hillocks as well as 2D islands show an elongated, lens shaped morphology with pronounced tips in the < 110 > direction. The ratio of nu(step) < 1110 >/nu(step) < 001 > is reduced to approximate to 2-4 when commercial grade lysozyme (purity: 98.5%) is used. The morphology of the hillocks/islands changes from the lens-shaped one to a rounded one. The step velocity into the fast growing < 110 > direction is significantly more affected by impurities than the growth into the < 001 > direction. The step velocity of monolayer islands (5.6 nm in height), of multilayer islands and of growth spirals is similar within the accuracy of the measurements. On the topside, the crystal is exposed to protein solution of approximate to 0.5 mm width. This results in convective mass transport conditions. On the backside of the crystal, there is a small gap of a few hundred nanometers. Within this gap, the crystal is growing under diffusive transport conditions. Changing the focus position from the topside of the crystal to the backside, the growth can be observed on the same crystal under convective as well as under diffusive conditions. Using commercial grade lysozyme, the growth velocity is higher under diffusive conditions than under convectively dominated ones. The morphology of the islands grown from a commercial grade solution under diffusive mass transport conditions is similar to the island morphology obtained otherwise only from high-purity solutions. Using high-purity solution, the step velocity and the island morphology does not differ as a function of the mass transport conditions. These results prove the extension of the depletion zone of the impurities and the reduced transport of impurities toward the growing interface under diffusive transport conditions. (c) 2006 Elsevier B.V. All rights reserved.
• Intermixing of Ge and Si during exposure of GeH4 on Si

  G Watari, N Usami, Y Nose, K Fujiwara, G Sazaki, K Nakajima

  THIN SOLID FILMS 508 (1-2) 163 - 165 0040-6090 2006/06 [Refereed][Not invited]
   

  Exposure of GeH4 on Si was attempted at various temperatures to establish growth conditions for high-quality Ge on Si or Si-on-insulator, which could be utilized for on-chip 1.3-1.55 mu m photodetectors. The grown film was found to be not pure-Ge but Ge-rich SiGe, and Si composition in the film increased with the rise of the growth temperature. This behavior could be utilized for growth of Ge on a compositionally graded SiGe buffer layer just by decreasing growth temperature. In fact, a preliminary experiment in order to obtain such a structure was successfully demonstrated by decreasing temperature from 700 to 500 degrees C at a rate of -6.7 degrees C/min. (c) 2005 Elsevier B.V. All rights reserved.
• In situ observation of dislocations in protein crystals during growth by advanced optical microscopy

  G Sazaki, K Tsukamoto, S Yai, M Okada, K Nakajima

  CRYSTAL GROWTH & DESIGN 5 (5) 1729 - 1735 1528-7483 2005/09 [Refereed][Not invited]
   

  We attempted to visualize defects in a tetragonal lysozyme crystal in situ by laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM). Birefringence microscopy (BM) and phase-contrast microscopy (PCM) were also employed for the in situ observations. LCM-DIM enabled us to observe the {1 10} surfaces of the crystals and visualize the strain fields around the dislocations normal to a light beam with sufficient contrast during growth for the first time. Relatively large inclusions (60 to 300 mu m) inside the crystal could also be visualized during growth, with the use of BM and PCM. We found that the dislocations appeared in bundles and were probably generated at the periphery of the relatively large inclusions inside the crystal. The existence of the dislocations was confirmed by etching experiments, in which we observed two kinds of etch pits: those with a point bottom and those with a flat bottom; the former corresponded to the dislocations inside the crystal and the latter corresponded to microdefects. Two different critical undersaturations existed above which the point-bottomed and flat-bottomed etch pits started to appear. The critical undersaturation for the point-bottomed etch pits was definitely less than that for the flat-bottomed ones. In the central region of the spiral growth hillock were many point-bottomed etch pits corresponding to the dislocations but not contributing to the formation of spiral growth steps. Although the point-bottomed etch pits were formed in only the central region of the spiral growth hillock, the flat-bottomed ones were randomly formed all over the {110} surfaces.
• Crystal quality of a 6H-SiC layer grown over macrodefects by liquid-phase epitaxy: a Raman spectroscopic study

  T Ujihara, S Munetoh, K Kusunoki, K Kamei, N Usami, K Fujiwara, G Sazaki, K Nakajima

  THIN SOLID FILMS 476 (1) 206 - 209 0040-6090 2005/04 [Refereed][Not invited]
   

  Liquid-phase epitaxial (LPE) growth, on silicon carbide. simultaneously covers macroscale defects, e.g., micropipes, and improves the quality of the crystal. In this study, an epi-layer grown over a macrodefect was evaluated by micro-Raman scattering spectroscopy. Before the growth process, the density of the stacking fault was high and the carrier density spatially inhomogeneous in the vicinity of the macrodefects. On the other hand, after growth, the layer over the macrodefect displayed good quality; the density of the stacking fault was less than that before growth and the homogeneity of the carrier density improved. (c) 2004 Elsevier B.V. All rights reserved.
• High-pressure acceleration of the growth kinetics of glucose isomerase crystals

  Y Suzuki, G Sazaki, T Matsui, K Nakajima, K Tamura

  JOURNAL OF PHYSICAL CHEMISTRY B 109 (8) 3222 - 3226 1520-6106 2005/03 [Refereed][Not invited]
   

  The growth and dissolution rates of glucose isomerase crystals (11 0 11 face) were measured in situ at 0.1 and 100 MPa. From these data, we determined that the solubilities at 25 degreesC were C-e = 3.1 +/- 0.9 and 2.6 +/- 0.5 mg mL(-1) at 0.1 and 100 MPa, respectively. At the same supersaturation of sigma = 2.5 (or ln(C/C-e), C = the concentration of glucose isomerase, C-e = the solubility) and temperature (T = 25 degreesC), the growth rate under 100 MPa was 7.6 times larger than that under 0.1 MPa. This result shows, for the first time, a kinetic acceleration of the growth rates of protein crystals with increasing pressure. The growth rates vs sigma data fitted well with a two-dimensional nucleation growth model of a polynucleation type. The fitting results indicate that the acceleration is mainly due to the decrease in the molecular surface energy of the glucose isomerase crystal with pressure.
• Structural consequences of hen egg-white lysozyme orthorhombic crystal growth in a high magnetic field: validation of X-ray diffraction intensity, conformational energy searching and quantitative analysis of B factors and mosaicity

  S Saijo, Y Yamada, T Sato, N Tanaka, T Matsui, G Sazaki, K Nakajima, Y Matsuura

  ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY 61 207 - 217 0907-4449 2005/03 [Refereed][Not invited]
   

  A novel method has been developed to improve protein-crystal perfection during crystallization in a high magnetic field and structural studies have been undertaken. The three-dimensional structure of orthorhombic hen egg-white (HEW) lysozyme crystals grown in a homogeneous and static magnetic field of 10 T has been determined and refined to a resolution of 1.13 Angstrom and an R factor of 17.0%. The 10 T crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 56.54 (3), b = 73.86 (6), c = 30.50 (2) Angstrom and one molecule per asymmetric unit. A comparison of the structures of the 0 T and 10 T crystals has been carried out. The magnitude of the structural changes, with a root-mean-square deviation value of 0.75 Angstrom for the positions of all protein atoms, is similar to that observed when an identical protein structure is resolved in two different crystalline lattices. The structures remain similar, with the exception of a few residues e.g. Arg68, Arg73, Arg128 and Gln121. The shifts of the arginine residues result in very significant structural fluctuations, which can have large effects on a protein's crystallization properties. The high magnetic field contributed to an improvement in diffraction intensity by (i) the displacement of the charged side chains of Arg68 and Arg73 in the flexible loop and of Arg128 at the C-terminus and (ii) the removal of the alternate conformations of the charged side chains of Arg21, Lys97 or Arg114. The improvement in crystal perfection might arise from the magnetic effect on molecular orientation without structural change and differences in molecular interactions. X-ray diffraction and molecular-modelling studies of lysozyme crystals grown in a 10 T field have indicated that the field contributes to the stability of the dihedral angle. The average difference in conformational energy has a value of -578 U mol(-1) per charged residue in favour of the crystal grown in the magnetic field. For most protein atoms, the average B factor in the 10 T crystal shows an improvement of 1.8 Angstrom(2) over that for the 0 T control; subsequently, the difference in diffraction intensity between the 10 T and 0 T crystals corresponds to an increase of 22.6% at the resolution limit. The mosaicity of the 10 T crystal was better than that of the 0 T crystal. More highly isotropic values of 0.0065, 0.0049 and 0.0048degrees were recorded along the a, b and c axes, respectively. Anisotropic mosaicity analysis indicated that crystal growth is most perfect in the direction that corresponds to the favoured growth direction of the crystal, and that the crystal grown in the magnetic field had domains that were three times the volume of those of the control crystal. Overall, the magnetic field has improved the quality of these crystals and the diffracted intensity has increased significantly with the magnetic field, leading to a higher resolution.
• Investigations on electromigration phenomena for protein crystallization using crystal growth cells with multiple electrodes: effect of the potential control

  Elizabeth Nieto-Mendoza, Bernardo A. Frontana-Uribe, Gen Sazaki, Abel Moreno

  JOURNAL OF CRYSTAL GROWTH 275 (1-2) E1437 - E1446 0022-0248 2005/02 [Refereed][Not invited]
   

  Investigations on electromigration phenomena for protein crystallization in gels and solution using a crystal growth cell with multiple electrodes at constant current (2 mu A per circuit) are discussed. In this work, the advantages and disadvantages of different electrode dispositions number, and electrode connections inside the cell are shown. A pH change effect was discarded as the main factor affecting the selective growth of the crystals at the cathode and the fact is explained in terms of electromigration phenomena. Additionally, controlled potential experiments were carried out in order to avoid parasitic reactions observed at constant current, resulting in an increase of reproducibility and better control of crystal growth. (C) 2004 Elsevier B. V. All rights reserved.
• Effects of vicinal steps on the island growth and orientation of epitaxially grown perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) thin film crystals on a hydrogen-terminated Si(111) substrate

  G Sazaki, T Fujino, N Usami, T Ujihara, K Fujiwara, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 273 (3-4) 594 - 602 0022-0248 2005/01 [Refereed][Not invited]
   

  On flat and off-cut Si(1 1 1) substrates terminated with monohydride, thin film crystals of organic semiconductor perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) were grown by molecular beam epitaxy (MBE) and were observed by atomic force microscopy (AFM). The thin film crystals on the hydrogen-terminated Si(1 1 1) surface (H-Si(1 1 1)) have a mesa-type island shape. On the flat H-Si(1 1 1) (average step distance > 500 rim, off-angle < 0.04degrees), with an increase in a thin film thickness, the size and number of the PTCDA islands were increased and decreased, respectively. These results show that the islands coalesced during the growth. After the coalescence of the islands, some islands became single crystals and the others became polycrystals. The ratio of the single crystal islands was estimated from the shapes of the islands. We found that the ratio of the single crystal islands after the coalescence was 48% and this value was much larger than a probability (1/6) estimated from an epitaxial relation. This result suggests that Ostwald ripening occurred in the PTCDA/H-Si(1 1 1) system. The PTCDA thin film crystals were also grown on the off-cut H-Si(1 1 1) (average step distance = 10 nm, off-angle = 1.8degrees). The number of the islands was much larger than that on the flat H-Si(1 1 1) and this result shows that the vicinal steps on the surface can work as effective nucleation sites. Coalescence of the islands was also observed on the off-cut H-Si(I 1 1). After the coalescence, the ratio of the single crystal islands on the off-cut H-Si(1 1 1) was 10% larger than that on the flat H-Si(1 1 1). This result shows that the orientation of the PTCDA islands can be controlled using the vicinal steps on the Substrate surface. (C) 2004 Elsevier B.V. All rights reserved.
• Growth of InGaAs and SiGe homogeneous bulk crystals which have complete miscibility in the phase diagrams

  K Nakajima, Y Azuma, N Usami, G Sazaki, T Ujihara, K Fujiwara, T Shishido, Y Nishijima, T Kusunoki

  INTERNATIONAL JOURNAL OF MATERIALS & PRODUCT TECHNOLOGY 22 (1-3) 185 - 212 0268-1900 2005 [Refereed][Not invited]
   

  Growth of binary and ternary single crystals which have complete miscibility in the phase diagrams, have been studied by several newly developed methods such as the liquid encapsulated Czochralski, Bridgman, and multi-component zone melting methods for InGaAs bulk crystals, and the multi-component zone melting methods and Bridgman methods for Ge-rich and Si-rich SiGe bulk crystals. Crystals grown by these methods are compared with each other, to find the proper growth conditions to obtain single crystals with uniform composition. Techniques for the precise control of the temperature at the growing interface and for the continuous supply of the depleted solute elements to the growth melt were developed. InGaAs bulk crystals with uniform composition were obtained by the multicomponent zone melting method. Si-rich and Ge-rich SiGe bulk crystals with uniform composition were obtained in the Ge compositional range from 10 to 78%. The advanced technologies to obtain the InGaAs and SiGe bulk crystals with much higher-quality are discussed in this paper.
• Investigation of crystal growth behavior of silicon melt for growing high quality polycrystalline silicon by cast method

  K Fujiwara, N Usami, Y Nose, G Sazaki, K Nakajima

  Conference Record of the Thirty-First IEEE Photovoltaic Specialists Conference - 2005 1081 - 1083 0160-8371 2005 [Refereed][Not invited]
   

  We investigated crystal growth behaviors of silicon melt by using an in-situ monitoring system consisting of a furnace and a microscope. Morphology of solid/liquid interface and directional growth processes of polycrystalline silicon were directly observed. We found two kinds of grain expanding mechanisms. It is suggested that we can control a dominant orientation on a wafer surface of polycrystalline silicon by controlling those two mechanisms during casting method.
• Molten metal flux growth and properties of CrSi2

  T Shishido, S Okada, Y Ishizawa, K Kudou, K Iizumi, Y Sawada, H Horiuchi, K Inaba, T Sekiguchi, J Ye, S Miyashita, A Nomura, T Sugawara, K Obara, M Oku, K Fujiwara, T Ujihara, G Sazaki, N Usami, S Kohiki, Y Kawazoe, K Nakajima

  JOURNAL OF ALLOYS AND COMPOUNDS 383 (1-2) 319 - 321 0925-8388 2004/11 [Refereed][Not invited]
   

  Single crystals of CrSi2 were obtained in the form of hexagonal prisms by the solution growth method using molten tin as a flux. The maximum size of the crystal is about 0.3 mm in diameter and 25 mm in length. The crystal structure of CrSi2 has hexagonal symmetry with space group P6(2)22 and the lattice parameters are a = 0.425(2) nm and c = 0.6375(1) nm, respectively. The crystals are semiconducting. The value of the micro-Vickers hardness for the {1100} face with hexagonal symmetry is 11.2 +/- 0.4 GPa. Weight gain of the crystals heated up to 1473 K in air is negligible. (C) 2004 Elsevier B.V. All rights reserved.
• On the origin of strain fluctuation in strained-Si grown on SiGe-on-insulator and SiGe virtual substrates

  K Kutsukake, N Usami, T Ujihara, K Fujiwara, G Sazaki, K Nakajima

  APPLIED PHYSICS LETTERS 85 (8) 1335 - 1337 0003-6951 2004/08 [Refereed][Not invited]
   

  We investigated the microscopic strain fluctuation in strained-Si grown on SiGe-on-insulator (SGOI) and SiGe virtual substrates, and clarified the origins of the strain fluctuation in the strained-Si film. A periodic strain fluctuation, which reflects a cross-hatch pattern of the substrate, was observed in the sample on the virtual substrate. On the other hand, a featureless strain fluctuation with suppressed amplitude was observed in the sample on SGOI substrate. By analyzing the correlation of the Raman peak positions of the Si-Si modes in strained-Si and SiGe, the dominant mechanism of the strain fluctuation in the strained Si film was found to be the compositional fluctuation in underlying SiGe for the sample on SGOI, and the strain fluctuation reflecting the cross-hatch pattern for the sample on the virtual substrate, respectively. (C) 2004 American Institute of Physics.
• Grain growth behaviors of polycrystalline silicon during melt growth processes

  K Fujiwara, Y Obinata, T Ujihara, N Usami, G Sazaki, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 266 (4) 441 - 448 0022-0248 2004/06 [Refereed][Not invited]
   

  We investigated the grain growth behaviors of polycrystalline silicon during directional growth from melt. Two types of grain growth behaviors were directly observed using an in situ monitoring system. In the first, when the moving velocity of solid-liquid growth interface is slow and the interfacial morphology is flat, a grain with a plane of lower surface energy with respect to the growth direction expands to lateral direction. In the second, when the interface moves fast and it has an irregular shape because of the differences of the growth rate among grains, a faster growing grain competitively expands to lateral direction covering the slower one. We suggested that the undercooling at the growth front is the key parameter to divide those growth behaviors. (C) 2004 Elsevier B.V. All rights reserved.
• Effects of growth temperature on the surface morphology of silicon thin films on (111) silicon monocrystalline substrate by liquid phase epitaxy

  T Ujihara, E Kanda, K Obara, K Fujiwara, N Usami, G Sazaki, A Alguno, T Shishido, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 266 (4) 467 - 474 0022-0248 2004/06 [Refereed][Not invited]
   

  We investigated the effects of growth temperature on the surface morphology of silicon layers grown by liquid phase epitaxy method on a (1 1 1) oriented silicon substrate in a relatively low-temperature range from 600degreesC to 900degreesC using Au-Bi alloy solvent. Layers are formed in the following growth sequence: (1) commencing in the form of initial nuclei as starting points of growth, (2) these structures grow along lateral and vertical directions as island structures, and (3) coalesce each other. Moreover, it was made clear that flat layers tend to cover the substrate completely at high growth temperature, in order to clarify the main factor that influences the surface morphology, an empirical model of the growth process was constructed. As a result, the temperature dependence of the surface morphology mainly depends on the temperature dependence of the preferential growth direction of Si on Si (1 1 1). (C) 2004 Elsevier B.V. All rights reserved.
• Effects of high pressure on the solubility and growth kinetics of monoclinic lysozyme crystals

  T Asai, Y Suzuki, G Sazaki, K Tamura, T Sawada, K Nakajima

  CELLULAR AND MOLECULAR BIOLOGY 50 (4) 329 - 334 0145-5680 2004/06 [Refereed][Not invited]
   

  Average growth rates of the (0 1 0) and (0 (1) over bar0) faces (R-<0 1 0>) of monoclinic lysozyme crystals were measured in situ under 0.1 and 100 MPa. From the dependence of the growth rates on the lysozyme concentration, we determined the solubility of the crystal as a function of temperature at 0.1 and 100 MPa. The solubility increased with an increase in pressure. From the comparison between the growth rates under 0.1 and 100 MPa at the same supersaturation level, we found that the growth rates of the monoclinic lysozyme crystals kinetically increase with an increase in pressure. Supersaturation dependencies of the growth rates under 0.1 and 100 MPa were well fitted with a two-dimensional (2D) nucleation growth model of a birth-and-spread type. The fitting results suggest that the increase in the growth rates with pressure can be explained by the decrease in the average ledge surface energy of 2D island, the average distance between the kinks on a step and the activation energies in the incorporation processes of solute molecules.
• Effects of spacer thickness on quantum efficiency of the solar cells with embedded Ge islands in the intrinsic layer

  A Alguno, N Usami, T Ujihara, K Fujiwara, G Sazaki, K Nakajima, K Sawano, Y Shiraki

  APPLIED PHYSICS LETTERS 84 (15) 2802 - 2804 0003-6951 2004/04 [Refereed][Not invited]
   

  We report on the effects of spacer thickness on the external quantum efficiency (EQE) of the solar cells with Ge islands embedded into the intrinsic region of the Si-based p-i-n diode. The EQE response of the solar cells in the near-infrared region is dependent on the spacer thickness that separates the layers of self-assembled Ge islands. It was found that the EQE response has an optimum value when the spacer thickness can sustain a good vertical ordering of islands. On the other hand, random nucleation of islands due to a thicker spacer layer exhibits an inferior EQE response. Furthermore, a drastic decrease of the EQE response of the solar cells for a thinner spacer layer was observed. (C) 2004 American Institute of Physics.
• A Novel Approach to Protein Crystallization : Use of a Magnetic Field and High-Pressure

  SAZAKI Gen, YANAGIYA Shin-ichiro, SUZUKI Yoshihisa, MIYASHITA Satoru, SATO Takao, MATSUURA Yoshiki, MATSUI Takuro, NAKAJIMA Kazuo

  Seibutsu Butsuri 日本生物物理学会 44 (2) 58 - 63 0582-4052 2004/03/25 

  A magnetic field and high-pressure are effective parameters to control protein crystallization. A magnetic field significantly affects the number, orientation and growth rate (morphology) of protein crystals and damps the buoyancy convection in protein solutions. Quality of protein crystals can be also improved by a magnetic field. The improvement in the crystal quality is due to a magnetic orientation effect. High-pressure can also give large effects on the solubility and growth kinetics of protein crystals. Changes in the solubility with pressure results from a difference in the volume between bulk water and the water hydrating the contact regions of protein molecules inside the crystal.
• The use of a new ad hoc growth cell with parallel electrodes for the nucleation control of lysozyme

  A Moreno, G Sazaki

  JOURNAL OF CRYSTAL GROWTH 264 (1-3) 438 - 444 0022-0248 2004/03 [Refereed][Not invited]
   

  In this work, the effects of an internal electric field (a direct current) on the crystallization of hen egg-white lysozyme were investigated. The crystallization was carried out in solution and gel placed in a crystallization cell. This crystallization growth cell has two parallel Pt electrodes (0.2 mm diameter and 15 mm length), and those electrodes were in contact with crystallization media. A direct current of 2.0 muA was applied (1.9 x 10(-3)V) for 8 h in solution and 12 h in gel media. During the crystallization, no generation of gas was observed. Lysozyme crystals appeared only around the cathode (negatively charged electrode), while amorphous precipitation was observed around the anode (positively charged electrode). By applying the direct current, the number of the deposited crystals was significantly decreased, and consequently the size of the crystals was increased. The direct current also decreased the induction time of nucleation. No significant change in pH was observed during the crystallization. The deposition of the crystals only around the cathode and the decrease in the induction time can be explained by an opposite polarity of the lysozyme molecules and the electrodes and by interactions between the lysozyme molecules and the Cl- in the vicinity of the electrodes. Electric potential generated by an electric field would be also responsible for the decrease in the number of the deposited crystals. (C) 2004 Elsevier B.V. All rights reserved.
• Fabrication of SiGe-on-insulator by rapid thermal annealing of Ge on Si-on-insulator substrate

  K Kutsukake, N Usami, K Fujiwara, T Ujihara, G Sazaki, K Nakajima, BP Zhang, Y Segawa

  APPLIED SURFACE SCIENCE 224 (1-4) 95 - 98 0169-4332 2004/03 [Refereed][Not invited]
   

  We report on fabrication of SiGe single crystal film on insulator by a simple approach including a growth of a thin Ge film on a commercially available Sol substrate, formation of a SiO2 protective layer, and rapid thermal annealing (RTA) in an Ar atmosphere. Homogeneity of the local Si fraction in SiGe-on-insulator (SGOI) was found to be closely connected with the SiGe phase diagram, and RTA below the solidus line is required to obtain homogeneous SGOI. In spite of the high annealing temperature beyond the melting point of Ge, obtained SGOI was revealed to be single crystalline as evidenced by electron back scattering pattern analysis. (C) 2003 Elsevier B.V All rights reserved.
• Fabrication of solar cell with stacked Ge islands for enhanced absorption in the infrared regime

  N Usami, A Alguno, K Sawano, T Ujihara, K Fujiwara, G Sazaki, Y Shiraki, K Nakajima

  THIN SOLID FILMS 451 604 - 607 0040-6090 2004/03 [Refereed][Not invited]
   

  We fabricated Si-based solar cell with stacked Ge islands grown via the Stranski-Krastanov growth mode in the intrinsic layer of pin diodes. The onset of the external quantum efficiency in the near infrared regime was extended up to approximately 1.4 mum for the solar cells with stacked Ge islands. The quantum efficiency was found to increase with increasing number of stacking, showing that a part of electron-hole pairs generated within Ge islands was separated by the internal electric field and contributed to the photocurrent. Increase of the processing temperature for the impurity diffusion was found to bring blue-shift of the band gap through the intermixing of Si and Ge as well as the deformation of Ge islands. Therefore, low-temperature process was suggested to be necessary for further enhancement of quantum efficiency in the near infrared regime. (C) 2003 Elsevier B.V. All rights reserved.
• In-situ observations of melt growth behavior of polycrystalline silicon

  K Fujiwara, Y Obinata, T Ujhara, N Usami, G Sazaki, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 262 (1-4) 124 - 129 0022-0248 2004/02 [Refereed][Not invited]
   

  Melt growth behavior of polycrystalline silicon was observed using a newly developed in-situ monitoring system consisting of a furnace and a microscope. It is possible to perform a directional growth from seed crystal or crucible wall and to observe the growth interface by using this system. Differences of growth rate or interfacial morphology among each grain of polycrystalline silicon were observed during melt growth. The Mullins-Sekerka instability of growth interface was also observed in a silicon melt for the first time. This observation system is confirmed to become a useful tool for revealing the growth mechanism of polycrystalline silicon. (C) 2003 Elsevier B.V. All rights reserved.
• Epitaxial relation and island growth of perylene-3.4.9.10-tetracarboxylic dianhydride (PTCDA) thin film crystals on a hydrogen-terminated Si(111) substrate

  G Sazaki, T Fujino, JT Sadowski, N Usami, T Ujihara, K Fujiwara, Y Takahashi, E Matsubara, T Sakurai, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 262 (1-4) 196 - 201 0022-0248 2004/02 [Refereed][Not invited]
   

  Surface of an off-cut Si(1 1 1) substrate with an average step distance of 100 Angstrom was terminated with monohydride. On this substrate, thin film crystals of organic semiconductor PTCDA were grown by molecular beam epitaxy (MBE). Surface of the thin film crystals on the hydrogen-terminated Si(1 1 1) surface (H-Si(1 1 1)) were observed using ultra-high vacuum scanning tunneling microscopy (UHV-STM) and atomic force microscopy (AFM). The PTCDA thin film crystals had an island shape of Volmer-Weber type. From the direction of the vicinal steps of the substrate [1 (1) over bar 0], we determined the size and orientation of the PTCDA thin film crystals on the H-Si(1 1 1). Long-axis of the two-dimensional (2D) unit cell of the thin film crystals matches the vector (6, 2) of the H-Si(1 1 1) surface. We proposed two conceivable epitaxial relations: one is ((6)(2/3) (2)(11/3)) and the other is point-on-line coincidence. 2D unit cells of the thin film crystals have widely stretched structure (2-10%), and the island growth of Volmer-Weber type is probably due to this large lattice misfit. (C) 2003 Elsevier B.V. All rights reserved.
• In situ observation of elementary growth steps on the surface of protein crystals by laser confocal microscopy

  G Sazaki, T Matsui, K Tsukamoto, N Usami, T Ujihara, K Fujiwara, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 262 (1-4) 536 - 542 0022-0248 2004/02 [Refereed][Not invited]
   

  Surface micro-topography of the {110} faces of tetragonal lysozyme crystals was observed in situ by laser confocal microscopy (LCM) combined with differential interference contrast microscopy (DIM). We could observe two-dimensional (213) nucleation and subsequent growth of the 2D islands in real time. When steps of neighboring 2D islands coalesced, the contrast of the steps disappeared completely and the 2D islands merged smoothly. This result proved that the height of the steps observed by LCM combined with DIM was always the same and these steps were elementary ones (5.6 nm high). The combination of LCM and DIM was necessary to observe elementary steps with sufficient contrast. The elementary steps on a spiral growth hillock could also be observed using the LCM-DIM system, although their contrast was much smaller than that of the 2D islands because of much smaller inter-step distance. (C) 2003 Elsevier B.V. All rights reserved.
• Novel coupling effects of the magnetic and electric fields on protein crystallization

  G Sazaki, A Moreno, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 262 (1-4) 499 - 502 0022-0248 2004/02 [Refereed][Not invited]
   

  Novel effects of combining the magnetic and internal electric fields on protein crystallization were studied in this report. Homogeneity in crystal size and ratio of magnetically orientated crystals were significantly increased, when a homogeneous magnetic field of 10T and an internal electric field (a direct current of 2 muA) were applied to the crystallization of hen egg-white lysozyme at the same time. When the directions of the magnetic field and the electric current were parallel, there were not significant effects observed. This result suggests that the Lorenz force is responsible for the coupling effects of the magnetic and internal electric fields. (C) 2003 Elsevier B.V. All rights reserved.
• Relationship between device performance and grain boundary structural configuration in a solar cell based on multicrystalline SiGe

  N Usami, WG Pan, K Fujiwara, T Ujihara, G Sazaki, K Nakajima

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS 43 (2B) L250 - L252 0021-4922 2004/02 [Refereed][Not invited]
   

  The grain boundary character distribution of multicrystalline SiGe (mc-SiGe) solar cells with microscopic compositional distribution was revealed to have a significant effect on the photovoltaic performance of solar cells. This was clarified by comparing the photovoltaic performance of small-area (approximate to0.02 cm(2)) solar cells fabricated in a large-area solar cell with their local structures. With increasing fraction of random grain boundaries in a small-area solar cell, the conversion efficiency was found to decrease. On the other hand, Sigma3 grain boundaries are found to be dominant in a solar cell with good performance. These results suggest that the development of a crystal growth technique that fully controls the grain boundary character distribution is the key to improving the conversion efficiency of the solar cell based on multicrystalline semiconductors.
• Excellent Effect of Gallium Solvent on Preparation of High Lifetime Silicon Crystal by LPE Method

  Toru Ujihara, Yusuke Satoh, Kazuo Obara, Kozo Fujiwara, Gen Sazaki, Noritaka Usami, Toetsu Shishido, Kazuo Nakajima

  14th PVSEC, 26-30 January (2004) Chulalongkorn University, Bangkok, Thailand ?  2004 [Refereed][Not invited]
  
• Phase diagram of growth mode for the SiGe/Si heterostructure system with misfit dislocations

  K Nakajima, T Ujihara, N Usami, K Fujiwara, G Sazaki, T Shishido

  JOURNAL OF CRYSTAL GROWTH 260 (3-4) 372 - 383 0022-0248 2004/01 [Refereed][Not invited]
   

  The strain, surface and interface energies of the SiGe/Si (SiGe grown on Si) heterostructure system with and without misfit dislocations were calculated for the Frank-van der Merwe (FM), Stranski-Krastanov (SK) and Volmer-Weber (VW) growth modes essentially based on the three kinds of fundamental and simple structures. The free energies for each growth mode were derived from these energies, and it was determined as a function of the composition and layer thickness of SiGe on Si. By comparison of the free energies, the phase diagrams of the FM, SK and VW growth modes for the SiGe/Si system were determined. The (111) and (100) reconstructed surfaces were selected for this calculation. From the phase diagrams, it was found for the growth of SiGe on Si that the layer-by-layer growth such as the FM mode was easy to be obtained when the Ge composition is small, and the island growth on a wetting layer such as the SK mode was easy to be obtained when the Ge composition is large. The VW mode is energetically stable in the Ge-rich compositional range, but it is difficult for the VW mode to appear in the actual growth of SiGe on Si because the VW region is right above the SK region. The regions of the SK and VW modes for the (111) heterostructure are larger than those for the (100) one because the strain energy of the (111) face is larger than that of the (100) face. The regions of the SK and VW modes for the heterostructure with misfit dislocations are narrower than those for the one without misfit dislocations because the strain energy is much released by misfit dislocations. The phase diagrams roughly explain the behavior of the FM and SK growth modes of SiGe on Si. (C) 2003 Elsevier B.V. All rights reserved.
• A unique dye-decolorizing peroxidase, DyP, from Thanatephorus cucumeris Dec 1: heterologous expression, crystallization and preliminary X-ray analysis

  T Sato, S Hara, T Matsui, G Sazaki, S Saijo, T Ganbe, N Tanaka, Y Sugano, M Shoda

  ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY 60 149 - 152 0907-4449 2004/01 [Refereed][Not invited]
   

  The dye-decolorizing peroxidase DyP is a key enzyme in the decolorizing fungus Thanatephorus cucumeris Dec 1 that degrades azo and antraquinone dyes. The gene dyp from T. cucumeris Dec 1, which has low homology to other peroxidase genes, was cloned and transformed into Aspergillus oryzae and glycosylated DyP was expressed at high levels. Purified DyP was deglycosylated using GST Endo F1 and then crystallized in a strong magnetic field ( 10 T) at 283 K using ammonium sulfate as precipitant. X-ray diffraction data to 2.96 Angstrom resolution collected from a native crystal at the Photon Factory ( Tsukuba, Japan) showed that the crystal belonged to the hexagonal space group P6(5)22, with unit-cell parameters a = b = 136.15, c = 363.46 Angstrom. The asymmetric unit of the crystal contained four DyP molecules, with a corresponding Matthews coefficient (V-M) of 2.50 Angstrom(3) Da(-1) and a solvent content of 51%. Heavy-atom derivatives of DyP have been obtained and electron-density maps have been calculated. The haem is visible and continuous electron density between the haem and protein clearly indicates the location of the proximal histidine ligand.
• Crystal quality evaluation of 6H-SiC layers grown by liquid phase epitaxy around micropipes using micro-Raman scattering spectroscopy

  T Ujihara, S Munetoh, K Kusunoki, K Kamei, N Usami, K Fujiwara, G Sazaki, K Nakajima

  SILICON CARBIDE AND RELATED MATERIALS 2003, PRTS 1 AND 2 457-460 633 - 636 0255-5476 2004 [Refereed][Not invited]
   

  We performed homoepitaxial growth of 6H-SiC layers on substrates including micropipes by the LPE method and evaluated the crystal quality by Raman scattering spectroscopy. In particular, we focused on the crystal quality of layers covering micropipes. It was made clear that there is no stress due to morphological macroscopic defects in the crystal over micropipes. Moreover, LPE growth not only closes a micropipe but also reduces the inhomogeneity of carrier density which exists in the area of the micropipe before growth.
• High-temperature solution growth and characterization of chromium disilicide

  T Shishido, S Okada, Y Ishizawa, K Kudou, K Iizumi, Y Sawada, H Horiuchi, K Inaba, T Sekiguchi, JH Ye, S Miyashita, A Nomura, T Sugawara, K Obara, Y Murakami, K Fujiwara, T Ujihara, G Sazaki, N Usami, M Oku, Y Yokoyama, S Kohiki, Y Kawazoe, K Nakajima

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 42 (12) 7292 - 7293 0021-4922 2003/12 [Refereed][Not invited]
   

  Single crystals of CrSi2 were obtained in the form of hexagonal prisms by a high-temperature solution growth method using molten tin as a solvent. Their maximum dimensions were approximately 0.3 mm in diameter and 2.5 mm in length. The crystals had hexagonal symmetry with space group P6(2)22 and their lattice parameters were a=0.425(2) nm and c=0.6375(1) nm. The crystals were semi conducting. The value of the micro-Vickers hardness for the {1100} face with hexagonal symmetry was 11.2 +/- 0.4 GPa. The weight gain of the crystals heated to 1473 K in air was negligible.
• Enhanced quantum efficiency of solar cells with self-assembled Ge dots stacked in multilayer structure

  A Alguno, N Usami, T Ujihara, K Fujiwara, G Sazaki, K Nakajima, Y Shiraki

  APPLIED PHYSICS LETTERS 83 (6) 1258 - 1260 0003-6951 2003/08 [Refereed][Not invited]
   

  We report on the performance of solar cells with stacked self-assembled Ge dots in the intrinsic region of Si-based p-i-n diode. These dots were epitaxially grown on p-type Si(100) substrate via the Stranski-Krastanov growth mode by gas-source molecular beam epitaxy. Enhanced external quantum efficiency (EQE) in the infrared region up to 1.45 mum was observed for the solar cells with stacked self-assembled Ge dots compared with that without Ge dots. Furthermore, the EQE was found to increase with increasing number of stacking. These results show that electron-hole pairs generated in Ge dots can be efficiently separated by the internal electric field, and can contribute to the photocurrent without considerable recombination in Ge dots or at Ge/Si interfaces. (C) 2003 American Institute of Physics.
• Stacked Ge islands for photovoltaic applications

  N. Usami, A. Alguno, T. Ujihara, K. Fujiwara, G. Sazaki, K. Nakajima, K. Sawano, Y. Shiraki

  SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 4 (4) 1468-6996 2003/07 [Refereed][Not invited]
   

  Stacked Ge islands formed via the Stranski-Krastanov growth mode were incorporated into the intrinsic layer of Si-based pin diode to improve the performance of the solar cells in the near-infrared regime. The onset of the external quantum efficiency was extended up to around 1.4 mm for the solar cells with stacked Ge islands. The quantum efficiency was found to increase with increasing number of stacking, and the onset of the photocurrent response was in good agreement with room-temperature photoluminescence energy of the Ge islands. These results manifest that the Ge islands did play a role to increase the quantum efficiency. Furthermore, a part of electron-hole pairs generated within Ge islands was separated by the internal electric field and contribute to the photocurrent. (C) 2003 Elsevier Ltd. All rights reserved.
• Influence of the elastic strain on the band structure of ellipsoidal SiGe coherently embedded in the Si matrix

  N Usami, T Ichitsubo, T Ujihara, T Takahashi, K Fujiwara, G Sazaki, K Nakajima

  JOURNAL OF APPLIED PHYSICS 94 (2) 916 - 920 0021-8979 2003/07 [Refereed][Not invited]
   

  We report on a theoretical investigation of the elastic strain in an ellipsoidal SiGe inclusion coherently embedded in Si and its influence on the band structure of SiGe. The strain was calculated as a function of the Ge fraction in SiGe and the aspect ratio of the ellipsoid, and utilized to derive the shift of the band edge. When the principal axis of the ellipsoid was chosen to be parallel to [001], the band structure of SiGe was predicted to be Si like regardless of the aspect ratio. The band gap of strained SiGe was also calculated, and the deviation of the aspect ratio from unity was found to be effective to decrease the band gap due to the breaking of the crystal symmetry. These results suggest the importance of controlling strain, shape, and local Ge fraction in multicrystalline SiGe, which we propose as a promising material for solar cell applications. (C) 2003 American Institute of Physics.
• Effects of high pressure on the growth kinetics of orthorhombic lysozyme crystals

  Y Nagatoshi, G Sazaki, Y Suzuki, S Miyashita, T Matsui, T Ujihara, K Fujiwara, N Usami, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 254 (1-2) 188 - 195 0022-0248 2003/06 [Refereed][Not invited]
   

  Growth processes of the (0 1 1) and (0 (1) over bar 1) faces of an orthorhombic lysozyme crystal were observed in situ under 0.1 and 100 MPa, The growth rates of the (0 1 1) and (0 (1) over bar 1) faces were equal within an experimental error. From the comparison between the growth rates under 0.1 and 100 MPa at the same supersaturation level, we. found that the growth kinetics of the orthorhombic lysozyme crystals significantly decreases with an increase in pressure. Supersaturation dependencies of the growth rates under 0.1 and 100MPa were well fitted with a two-dimensional (2D) nucleation growth model of a birth-and-spread type. The fitting results show that the decrease in the growth kinetics with pressure can be explained by the increase activation energies in the incorporation processes of solute molecules. (C) 2003 Elsevier Science B.V. All rights reserved.
• Recrystallization of Cu-phthalocyanine on KCl (001) substrates by annealing method

  S Yanagiya, S Nishikata, G Sazaki, A Hoshino, K Nakajima, T Inoue

  JOURNAL OF CRYSTAL GROWTH 254 (1-2) 244 - 250 0022-0248 2003/06 [Refereed][Not invited]
   

  In order to establish the general way to prepare thin film crystals of organic semiconductors, we studied annealing effects on the heteroepitaxial growth of Cu-phthalocyanine (CuPc) crystallites on KCl {0 0 1} substrate crystals. CuPc was deposited on a cleaved KCl. single crystal by vacuum evaporation (under 10(-4)Torr). Then, the sample was taken out from the vacuum chamber and annealed in the air. On the CuPc as-deposited surface, no clear contrast was observed by scanning electron microscopy (SEM). On the contrary, many needle-like crystallites could be observed after the annealing treatment. Those crystallites were oriented so that their long axis was parallel to the <1 0 0> direction of the KCl substrate. We also investigated the effects of the annealing temperature and annealing duration time to find an optimal annealing condition. (C) 2003 Elsevier Science B.V. All rights reserved.
• Growth of SiGe bulk crystals with uniform composition by utilizing feedback control system of the crystal-melt interface position for precise control of the growth temperature

  Y Azuma, N Usami, T Ujihara, K Fujiwara, G Sazaki, Y Murakami, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 250 (3-4) 298 - 304 0022-0248 2003/04 [Refereed][Not invited]
   

  We developed an automatic feedback control system of the crystal-melt interface position to keep the temperature at the interface constant during growth, and demonstrate its successful application to grow Ge-rich SiGe bulk crystals with uniform composition. In this system, the position of the crystal-melt interface was automatically detected by analyzing the images captured,using in situ monitoring system based on charge-coupled-devices camera, and the pulling rate of the crucible was corrected at every 1 min. The system was found to be effective to keep the crystal-melt interface position during growth even when the variation of the growth rate is quite large. Especially, the interface position was kept for 470 h during growth of Ge-rich SiGe bulk crystal when we started with a long growth melt of 80 mm. As a result, a 23 mm-long Si(0.22)Geo(0.78) bulk crystal with uniform composition was obtained thanks to the constancy of the growth temperature during growth through the control of the interface position. Our technique opens a possibility to put multicomponent bulk crystal in a practical use. (C) 2002 Elsevier.Science B.V. All rights reserved.
• High-quality crystalline silicon layer grown by liquid phase epitaxy method at low growth temperature

  T Ujihara, K Obara, N Usami, K Fujiwara, G Sazaki, T Shishido, K Nakajima

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS 42 (3A) L217 - L219 0021-4922 2003/03 [Refereed][Not invited]
   

  We investigated the effect of growth temperature on crystal quality of crystalline silicon layers grown by liquid phase epitaxy (LPE) with gold-bismuth binary alloy solvent. The electrical and structural properties were examined by means of minority-carrier lifetime measurement and micro-Raman scattering spectroscopy. Both electrical and structural qualities improve with decreasing growth temperature. In the present study, the lifetime of the silicon layer grown at the lowest temperature was higher than that of monocrystalline silicon substrate though the solvent includes gold which is a well-known strong recombination site. On the other hand, the structural quality of layers is inferior to that of the substrate even at the lowest growth temperature. Thus, the temperature dependence of lifetime was concluded to be mainly due to the reduction of the solubility of gold impurity in the layer rather than the improvement of structural quality.
• Fabrication of SiGe-on-insulator through thermal diffusion of Ge on Si-on-insulator substrate

  K Kutsukake, N Usami, K Fujiwara, T Ujihara, G Sazaki, BP Zhang, Y Segawa, K Nakajima

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS 42 (3A) L232 - L234 0021-4922 2003/03 [Refereed][Not invited]
   

  We report on the fabrication of a homogeneous SiGe-on-insulator as a substrate for strained Si-on-insulator (SOI) metal-oxide-semiconductor field-effect-transistors. The fabrication process includes the growth of a thin Ge film on a commercially available SOI substrate at 100degreesC using a molecular beam epitaxy system, the formation of a SiO2 cap layer by radio-frequency sputtering, and rapid thermal annealing (RTA) in an Ar atmosphere. After RTA at an appropriate temperature, the SiGe-on-insulator with a laterally homogeneous Si fraction was successfully obtained by the formation of epitaxial SiGe on a thin SOI as a seed and interdiffusion of Ge and Si atoms. However, inhomogeneous SiGe films were obtained when the annealing temperature was very high. The conditions for the realization of SiGe with a homogeneous Si fraction were found to be closely related to the phase diagram of the Si-Ge binary alloy.
• Spatial distribution of composion and strain in multicrystalline SiGe bulk crystal and their impact on solar cell applications

  N Usami, T Takahashi, AC Alguno, K Fujiwara, T Ujihara, T Ichitsubo, G Sazaki, K Nakajima

  PROCEEDINGS OF 3RD WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION, VOLS A-C 98 - 101 2003 [Refereed][Not invited]
   

  We report on microscopic structural characterizations of multicrystalline SiGe (mc-SiGe) bulk crystal, which contains microscopic compositional distribution, and discuss possible influence on solar cell applications. By combining microscopic Raman spectroscopy and energy-dispersive x-ray analysis, the existence of built-in strain and its spatial distribution were experimentally obtained. By a simple calculation assuming ellipsoidal SiGe inclusion coherently embedded in Si-matrix, effect of the built-in strain on the band gap is quantitatively estimated. For example, an ellipsoidal Si0.5Ge0.5 inclusion with an aspect ratio less than 0.10 is predicted to have the similar band gap with unstrained Ge. Therefore, to utilize strain is concluded to be important to realize spectroscopic response in the near infrared regime with minimizing incorporation of Ge.
• Direct observations of crystal growth from silicon melt

  K Fujiwara, K Nakajima, T Ujihara, N Usami, G Sazaki, H Hasegawa, S Mizoguchi, K Nakajima

  PROCEEDINGS OF 3RD WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION, VOLS A-C 110 - 113 2003 [Refereed][Not invited]
   

  Crystal growth behavior from silicon melt was observed using a confocal scanning laser microscope with an infrared image furnace. The morphology of growth interface changed from planar to facet with increasing growth rate. The facet vanishing process was also observed. It was shown the (111) facet formed at a steady state. The undercooling in front of the facet interface was measured by an infrared camera and found to be almost 7 degrees. The growth behavior from silicon melt was explained by the analytical expression based on two-dimensional nucleation model.
• Structure and property of directionally grown SiGe multicrystals with microscopic compositional distribution

  K Fujiwara, T Takahashi, N Usami, T Ujihara, G Sazaki, K Nakajima

  PROCEEDINGS OF 3RD WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION, VOLS A-C 158 - 160 2003 [Refereed][Not invited]
   

  Mullticrystalline SiGe with microscopic compositional distributions is an attractive material for a new high efficiency solar cell because it has a possibility to absorb the near infrared light, which is transparent to Si. In this study, structural property and absorption coefficient was investigated for mc-SiGe and those were compared with mcSi. Columnar structure for mc-SiGe was obtained using directional growth method. It was found that the preferential crystallographic orientation of mc-SiGe is {110} plane, which is different from mc-Si. By measuring the absorption coefficient, we demonstrated that the introduction of microscopic compositional distribution in mc-SiGe is an effective way to increase absorption coefficient in longer wavelength. Mc-SiGe is therefore concluded to be promising for enabling the realization of low-cost and highly efficient solar cells.
• What is the most important growth parameter on crystal quality of the silicon layer by LPE method?

  T Ujihara, K Obara, N Usami, K Fujiwara, G Sazaki, T Shishido, K Nakajima

  PROCEEDINGS OF 3RD WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION, VOLS A-C 1241 - 1244 2003 [Refereed][Not invited]
   

  We investigated the effect of growth parameters, growth temperature, growth rate and solvent, on crystal quality of silicon thin layers grown by LPE method. Electrical and structural properties were examined by means of minority-carrier lifetime measurement and micro-Raman scattering spectroscopy. It was made clear that crystal quality strongly depends oil the growth temperature mainly due to equilibrium impurity solubility in the silicon layers. In addition, it is important to choose an appropriate solvent whose Solubility in crystalline silicon is low and effective capture cross section is small. In actual, we successfully grew the silicon layer of which the lifetime was higher than that of monocrystalline silicon crystal as a substrate.
• Improved quantum efficiency of solar cells with Ge dots stacked in multilayer structure

  A Alguno, N Usami, T Ujihara, K Fujiwara, K Sawano, G Sazaki, Y Shiraki, K Nakajima

  PROCEEDINGS OF 3RD WORLD CONFERENCE ON PHOTOVOLTAIC ENERGY CONVERSION, VOLS A-C 2746 - 2749 2003 [Refereed][Not invited]
   

  We report on the improved external quantum efficiency of solar cells in the infrared region with self-assembled Ge dots stacked in multilayer structure embedded within the intrinsic region of a p-i-n diode. This quantum efficiency was found to increase with increasing number of stacking. This indicates that additional photocarriers are generated in the Ge dots and have a high probability of escaping from the dots and/or at Ge/Si interfaces without significant recombination under the influence of the internal electric field.
• Strain distribution of Si thin film grown on multicrystalline-SiGe with microscopic compositional distribution

  N Usami, T Takahashi, K Fujiwara, T Ujihara, G Sazaki, Y Murakami, K Nakajima

  JOURNAL OF APPLIED PHYSICS 92 (12) 7098 - 7101 0021-8979 2002/12 [Refereed][Not invited]
   

  We report on growth and characterizations of Si/multicrystalline-SiGe (mc-SiGe) heterostructure as a promising candidate to surpass mc-Si solar cells. Spatial distribution of the status of strain in Si was investigated using microscopic Raman spectroscopy. The strain was found to be strongly influenced by the composition and microstructure of underlying mc-SiGe. Spatial variation of the strain as well as strain relaxation was found to be suppressed by decreasing average Ge composition of underlying SiGe. (C) 2002 American Institute of Physics.
• Significant decrease in the solubility of glucose isomerase crystals under high pressure

  Y Suzuki, G Sazaki, K Visuri, K Tamura, K Nakajima, S Yanagiya

  CRYSTAL GROWTH & DESIGN 2 (5) 321 - 324 1528-7483 2002/09 [Refereed][Not invited]
   

  Solubility of glucose isomerase (from Streptomyces rubiginosus) crystals was measured in situ at 0.1 and 100 MPa. An equilibrium temperature of the crystal with the solution of a given concentration was measured using a two-beam interferometer. The solubility of the crystal decreased to about one-ninth with increasing pressure from 0.1 to 100 MPa at 30 degreesC. This means that the supersaturation, sigma (= In C/C-e, C = protein concentration, C-e = solubility), increases significantly with increasing pressure at the same temperature. This strongly suggests that the substantial acceleration of the crystallization of glucose isomerase with increasing pressure reported by Visuri et al. is due to the significant decrease in the solubility. The enthalpy and entropy of the dissolution were estimated from the van't Hoff plots. The volume change accompanying the dissolution took a large positive value as DeltaV = 54 +/- 31 cm(3) mol(-1) at 30 degreesC.
• In situ observations of crystal growth behavior of silicon melt

  K Fujiwara, K Nakajima, T Ujihara, N Usami, G Sazaki, H Hasegawa, S Mizoguchi, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 243 (2) 275 - 282 0022-0248 2002/08 [Refereed][Not invited]
   

  Crystal growth behavior of silicon melt was observed using a confocal scanning laser microscope with an infrared image furnace. The morphology of the growth interface changed from planar to facet with increasing growth rate. The facet vanishing process was also observed. It was shown the (111) facet formed at a steady state. The undercooling in front of the facet interface was measured by an infrared camera and found to be almost 7degrees. The growth behavior of silicon melt was explained by an analytical expression based on a two-dimensional nucleation model. (C) 2002 Elsevier Science B.V. All rights reserved.
• Crystal structures of the reaction intermediate and its homologue of an extradiol-cleaving catecholic dioxygenase

  N Sato, Y Uragami, T Nishizaki, Y Takahashi, G Sazaki, K Sugimoto, T Nonaka, E Masai, M Fukuda, T Senda

  JOURNAL OF MOLECULAR BIOLOGY 321 (4) 621 - 636 0022-2836 2002/08 [Refereed][Not invited]
   

  BphC derived from Pseudomonas sp. strain KKS102 is an extradiol-cleaving catecholic dioxygenase. This enzyme contains a non-heme iron atom and plays an important role in degrading biphenyl/polychlorinated biphenyls (PCBs) in the microbe. To elucidate detailed structures of BphC reaction intermediates, crystal structures of the substrate-free form, the BphC-substrate complex, and the BphC-substrate-NO (nitric oxide) complex were determined. These crystal structures revealed (1) the binding site of the O-2 molecule in the coordination sphere and (2) conformational changes of His194 during the catalytic reaction. On the basis of these findings, we propose a catalytic mechanism for the extradiol-cleaving catecholic dioxygenase in which His194 seems to play three distinct roles. At the early stage of the catalytic reaction, His194 appears to act as a catalytic base, which likely deprotonates the hydroxyl group of the substrate. At the next stage, the protonated His194 seems to stabilize a negative charge on the O-2 molecule located in the hydrophobic O-2-binding cavity. Finally, protonated His194 seems to function as a proton donor, whose existence has been proposed. (C) 2002 Elsevier Science Ltd. All rights reserved.
• Growth and properties of SiGe multicrystals with microscopic compositional distribution for high-efficiency solar cells

  K Nakajima, N Usami, K Fujiwara, Y Murakami, T Ujihara, G Sazaki, T Shishido

  SOLAR ENERGY MATERIALS AND SOLAR CELLS 73 (3) 305 - 320 0927-0248 2002/07 [Refereed][Not invited]
   

  The growth technique and physical properties of SiGe multicrystals with microscopic compositional distribution are demonstrated for new high-efficiency solar cells in which the wavelength dependence of the absorption coefficient can be freely designed by controlling the compositional distribution in the SiGe multicrystals. This growth technique is suitable for the practical casting method, and it is made up of melt growth of SiGe multicrystals with wide and microscopic distribution of the composition from Si to Ge all over the crystals. It is studied how much widely the microscopic compositional distribution in SiGe multicrystals grown from binary Si-Ge melts can be controlled by the melt composition and the cooling process. The range of the microscopic compositional distribution becomes wider as the starting Si concentration in the growth melt becomes larger. SiGe multicrystals with various microscopic compositional distribution can be freely controlled by optimizing the melt composition and the cooling process. The wavelength dependence of the absorption coefficient of such SiGe multicrystals can also be freely designed. Using the experimentally determined absorption coefficient of a SiGe crystal with microscopic compositional distribution, the short circuit photo-current of solar cells was calculated and it is demonstrated that the short circuit photo-current can be much larger for SiGe with microscopic compositional distribution than for SiGe with uniform composition. Si thin film can be easily grown on such a SiGe multicrystal and the Si/SiGe heterostructure can be obtained. These results show that SiGe multicrystals with microscopic compositional distribution are hopeful for new high-efficiency solar cell applications by using the practical casting method. (C) 2002 Elsevier Science B.V. All rights reserved.
• Simultaneous in situ measurement of solute and temperature distributions in the alloy solutions

  T Ujihara, K Fujiwara, G Sazaki, N Usami, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 242 (3-4) 313 - 320 0022-0248 2002/07 [Refereed][Not invited]
   

  We established an in situ and simultaneous measurement system for solute distribution and temperature distribution in high-temperature solutions. The system consists of an infrared camera, an X-ray fluorescence spectrometer for concentration measurement and a sample stage with a two-zone heater. A sample holder is composed of some graphite parts with a quartz glass window at the bottom of holder for monitoring the infrared image. Concentration measurements are performed by the X-ray analysis through the graphite lid at the top of the holder. The present system was applied to the in situ measurement of the solute and temperature distributions in the gallium-zinc solution during the crystal growth by the solute supplied zone melting method. We selected the thin sample with the thickness of 500 pm to observe the solute distribution characterized by diffusion process. As a result, we successfully observed the process in which the solute distribution changed and consequently reached the stationary state due to the diffusion in the linear temperature gradient. These results show that the present system can be a powerful tool for actual survey of supercooling and supersaturation. (C) 2002 Elsevier Science B.V. All rights reserved.
• Evidence of the presence of built-in strain in multicrystalline SiGe with large compositional distribution

  N Usami, T Takahashi, K Fujiwara, T Ujihara, G Sazaki, Y Murakami, K Nakajima

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 41 (7A) 4462 - 4465 0021-4922 2002/07 [Refereed][Not invited]
   

  Multicrystalline SiGe (mc-SiGe) with microscopic compositional distribution, which has been proposed as a promising material for solar cell applications, was characterized by microscopic Raman spectroscopy. As expected, a strong spatial variation of Raman spectra was observed. However, the compositional distribution obtained by a separate energy-dispersive X-ray analysis did not fully explain the observed spatial variation of Raman spectra. A plausible explanation of the inconsistency is the existence of built-in strain, which originates from the lattice mismatch between Si and Ge.
• New method for measurement of interdiffusion coefficient in high temperature solutions based on Fick's first law

  T Ujihara, K Fujiwara, G Sazaki, N Usami, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 241 (3) 387 - 394 0022-0248 2002/06 [Refereed][Not invited]
   

  We propose a new method for determination of interdiffusion coefficient in high temperature solutions. This method can be characterized by the three following facts: the flux of diffusion is temporarily measured by in situ measurement technique for solution concentration in a diffusion cell; the intrinsic diffusion coefficient is derived from the flux on a basis of Fick's first law; the interdiffusion coefficients are evaluated from the intrinsic diffusion coefficients. In practice, the interdiffusion coefficient of GaZn binary system was successfully determined using the present method. (C) 2002 Elsevier Science B.V. All rights reserved.
• Compositional variation in Si-rich SiGe single crystals grown by multi-component zone melting method using Si seed and source crystals

  K Nakajima, T Kusunoki, Y Azuma, N Usami, K Fujiwara, T Ujihara, G Sazaki, T Shishido

  JOURNAL OF CRYSTAL GROWTH 240 (3-4) 373 - 381 0022-0248 2002/05 [Refereed][Not invited]
   

  The effect of the supply of depleted Si solute elements on the compositional variation in the Si-rich SiGe bulk crystals was studied using the method which was used to grow Ge-rich SiGe single crystals with a uniform composition. By selecting the proper pulling rate, we can obtain Si-rich Si1-xGex bulk crystals with uniform composition of x = 0.1 without using the supply mechanism of depleted Si solute elements. When the supply mechanism of Si solute elements was used. the initial composition in Si-rich SiGe crystals can be much more easily determined by controlling the growth temperature than that in Ge-rich crystals because the Si seed crystal is not melted down. The supply of Si solute elements is very effective to change the compositional variation even for Si-rich SiGe crystals. (C) 2002 Elsevier Science B.V. All rights reserved.
• Melt growth of multicrystalline SiGe with large compositional distribution for new solar cell applications

  K Nakajima, N Usami, K Fujiwara, Y Murakami, T Ujihara, G Sazaki, T Shishido

  SOLAR ENERGY MATERIALS AND SOLAR CELLS 72 (1-4) 93 - 100 0927-0248 2002/04 [Refereed][Not invited]
   

  The melt-growth conditions to obtain SiGe multicrystals with microscopic compositional distribution are presented. These SiGe multicrystals are useful for new solar cells whose wavelength dependence of the absorption coefficient can be freely designed. The multicrystals with wide compositional distribution from Si to Ge can be grown by a melt growth technique such as the practical casting method. In this work, it was studied as to how much the micro and macroscopic compositional distribution in SiGe multicrystals grown from binary Si-Ge melts could be controlled by the melt composition and the cooling process. Such SiGe multicrystals with wide distribution of the composition would also have wide distribution of the absorption coefficient, and could be hopeful for new solar cell applications using the practical casting method. (C) 2002 Elsevier Science B.V. All rights reserved.
• In-situ monitoring system of the position and temperature at the crystal-solution interface

  G Sazaki, Y Azuma, S Miyashita, N Usami, T Ujihara, K Fujiwara, Y Murakami, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 236 (1-3) 125 - 131 0022-0248 2002/03 [Refereed][Not invited]
   

  We developed an in-situ observation system of the position and temperature at the crystal-solution interface grown under high temperature. A zone furnace of vertical type has an optical window made of quartz glass, and a sample in the furnace can be directly observed from outside through this window. Beam splitter made of an Si single crystal reflects the visible light comming from the sample, and the visible light image is observed using a CCD camera. Infrared light emitted from the sample penetrates the beam splitter, and the infrared image is monitored by an infrared CCD camera (thermoviewer). A growth process of a SiGe mixed crystal was chosen as a model system. Using the newly developed in-situ monitoring system, the position of the growth interface could be monitored with a spatial resolution of 300 mum. Temperature distribution around the growth interface could be determined with a spatial resolution of 230 mum and an accuracy of +8degreesC. (C) 2002 Elsevier Science B.V. All rights reserved.
• Protein crystallization under high pressure

  Y Suzuki, G Sazaki, S Miyashita, T Sawada, K Tamura, H Komatsu

  BIOCHIMICA ET BIOPHYSICA ACTA-PROTEIN STRUCTURE AND MOLECULAR ENZYMOLOGY 1595 (1-2) 345 - 356 0167-4838 2002/03 [Refereed][Not invited]
   

  Pressure is expected to be an important parameter to control protein crystallization, since hydrostatic pressure affects the whole system uniformly and can be changed very rapidly. So far, a lot of studies on protein crystallization have been done. Solubility of protein depends on pressure. For instance, the solubility of tetragonal lysozyme crystal increased with increasing pressure, while that of orthorhombic crystal decreased. The solubility of subtilisin increased with increasing pressure. Crystal growth rates of protein also depend on pressure. The growth rate of glucose isomerase was significantly enhanced with increasing pressure. The growth rate of tetragonal lysozyme crystal and subtilisin decreased with increasing pressure. To study the effects of pressure on the crystallization more precisely and systematically, hen egg white lysozyme is the most suitable protein at this stage, since a lot of data can be used. We focused on growth kinetics under high pressure, since extensive studies on growth kinetics have already been done at atmospheric pressure, and almost all of them have explained the growth mechanisms well, The growth rates of tetragonal lysozyme decreased with pressure under the same supersaturation. This means that the surface growth kinetics significantly depends on pressure. By analyzing the dependence of supersaturation on growth rate, it was found that the increase in average ledge surface energy of the two-dimensional nuclei with pressure explained the decrease in growth rate. At this stage, it is not clear whether the increase in surface energy with increasing pressure is the main reason or not. Fundamental studies on protein crystallization under high pressure will be useful for high pressure crystallography and high pressure protein science. (C) 2002 Elsevier Science B.V. All rights reserved.
• Fabrication of SiGe bulk crystals with uniform composition as substrates for Si-based heterostructures

  N Usami, Y Azuma, T Ujihara, G Sazaki, K Fujiwara, Y Murakami, K Nakajima

  MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY 89 (1-3) 364 - 367 0921-5107 2002/02 [Refereed][Not invited]
   

  SiGe bulk crystal was grown by the multicomponent zone-melting method equipped with an in situ monitoring system of the position and the temperature at the crystal-solution interface. By utilizing the in situ monitoring system, an attempt was made to control the interface position at a fixed position during growth by balancing the growth rate and the pulling rate of the crystal. This led to realization of SiGe bulk crystal with Ge composition of 0.86 +/- 0.004 over 22 mm in length. However, as growth proceeds. development of small angle boundaries was evidenced by X-ray characterizations. This polycrystallization was found to be accompanied with appearance of deep-level emission in photoluminescence spectra. A preliminary result to grow SiGe with intermediate composition. which is important for Si-based heterostructures. was also performed. (C) 2002 Elsevier Science B.V. All rights reserved.
• Control of macroscopic absorption coefficient of multicrystalline SiGe by microscopic compositional distribution

  Noritaka Usami, Kozo Fujiwara, Toru Ujihara, Gen Sazaki, Hiroyuki Yaguchi, Yoshihiro Murakami, Kazuo Nakajima

  Japanese Journal of Applied Physics, Part 2: Letters 41 (1 A/B) L37 - L39 0021-4922 2002/01/15 [Refereed][Not invited]
   

  We report on the growth and optical characterizations of multicrystalline SiGe (mc-SiGe) with microscopic compositional distribution for solar cell applications. Mc-SiGe was grown by a simple technique based on the casting method. The compositional distribution and solidification structure of mc-SiGe were found to be strongly dependent on the cooling rate, suggesting that they can be controlled by the growth parameters. Spatial variation of the extinction coefficient, corresponding to the microscopic compositional distribution, was revealed by spectroscopic ellipsometry, and macroscopic optical properties were found to be controlled by the microscopic compositional distribution. The advantage of mc-SiGe was further revealed by the increased absorption in the lower energies compared with uniform SiGe with almost the same average composition.
• Erratum: Effects of pressure on growth kinetics of tetragonal lysozyme crystals (Journal of Crystal Growth (2000) 208 (638-644) PII: S0022024899005370)

  Yoshihisa Suzuki, Satoru Miyashita, Gen Sazaki, Toshitaka Nakada, Tsutomu Sawada, Hiroshi Komatsu

  Journal of Crystal Growth 234 (2-3) 610  0022-0248 2002 [Refereed][Not invited]
  
• Evaluation of mutual and intrinsic diffusion coefficients in the liquid GaGe binary system using novel determination method based on Fick's first law

  T. Ujihara, K. Fujiwara, G. Sazaki, N. Usami, K. Nakajima

  J. Non-Cryst. Solids 312-314 196-202  2002 [Refereed][Not invited]
  
• Effect of growth temperature on surface morphology and crystal quality of Si thin-film by liquid phase epitaxial growth technique

  Toru Ujihara, Eiji Kanda, Kozo Fujiwara, Noritaka Usami, Gen Sazaki, Kazuo Nakajima

  Proc. PV in Europe from PV Technology to Energy Solutions Conference and Exhibition, Palazzo dei Congressi, Roma, Italy, 7-11 October (2002) 408-411  2002 [Refereed][Not invited]
  
• Crystal growth of silicon-germanium homogeneous bulk crystal and related measurement

  UJIHARA Toru, AZUMA Yukinaga, USAMI Noritaka, SAZAKI Gen, FUJIWARA Kozo, SHISHIDO Toetsu, NAKAJIMA Kazuo

  J. Japanese association for crystal growth 日本結晶成長学会 29 (5) 339 - 348 0385-6275 2002 [Not refereed][Not invited]
   

  To prepare a silicon-germanium bulk crystal with uniform composition distribution, it is necessary to supply solute component to the growth interface and to control the growth interface temperature. The multicomponent zone melting method with the feedback system of the growth interface temperature which we established fulfills these necessary conditions. The homogeneous bulk crystal with the length of 20 mm over was successfully grown by this method. This paper provides an overview of this growth method and related in-situ techniques to measure position and temperature of growth interface during the crystal growth. To grow high quality crystals, it is also necessary to control supercooling and supersaturation in the solution. We also introduce an in-situ observation technique for supersaturation.
• In situ observation of the Marangoni convection in a NaCl aqueous solutions under microgravity

  G Sazaki, S Miyashita, M Nokura, T Ujihara, K Fujiwara, N Usami, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 234 (2-3) 516 - 522 0022-0248 2002/01 [Refereed][Not invited]
   

  Using a drop experiment facility. Maragnoni convection induced by a temperature gradient in a 7.35 wt% NaCl aqueous solution was observed in situ under microgravity in order to reveal Marangoni effects on the crystallization from aqueous solution in a spaceship. In the drop experiment, after microgravity was achieved, the buoyant convection diminished completely within 1.0 s. Since the flow rate became quite steady after 1.0 s of microgravity, this was regarded as the flow rate of Marangoni convection. The flow rates of Marangoni convection were also measured as a function of the exposure time of the solution surface to the surrounding air, The flow rate decreased exponentially with an increase in the exposure time. This decrease could be explained by a model containing Langmuir type adsorption of the air on the solution surface. Our result suggests that the solution surface would be entirely contaminated by the adsorbed gas molecules within several hours. and Marangoni convection would diminish. (C) 2002 Elsevier Science B.V. All rights reserved.
• Evaluation of the diffusion coefficients in liquid GaGe binary alloys using a novel method based on Fick's first law

  T Ujihara, K Fujiwara, G Sazaki, N Usami, K Nakajima

  JOURNAL OF NON-CRYSTALLINE SOLIDS 312-14 196 - 202 0022-3093 2002 [Refereed][Not invited]
   

  The intrinsic diffusion coefficients in a liquid GaGe alloy were determined using a novel method based on Fick's first law. The mutual and self diffusion coefficients also were derived. The intrinsic diffusion coefficients of both components are similar to each other and so both components equally contribute to the mutual diffusion coefficient. Also, the values of the self diffusion coefficient agree with values reported in the literature. A comparative study of the gallium self diffusion coefficients between the GaGe and GaZn systems indicated that the self diffusion coefficient depends on the second alloy component. (C) 2002 Elsevier Science B.V. All rights reserved.
• In situ measurements of the solubility of protein crystals under high pressure

  Y Suzuki, T Sawada, S Miyashita, G Sazaki, T Nakada, H Komatsu, T Arao, K Tamura

  TRENDS IN HIGH PRESSURE BIOSCIENCE AND BIOTECHNOLOGY, PROCEEDINGS 19 117 - 122 0921-0423 2002 [Refereed][Not invited]
   

  Using a two-beam interferometer and a high-pressure cell with transparent windows, we measured the solubility of lysozyme crystals under high pressure in situ. The change in the concentration with time during equilibration was measured accurately and continuously starting from a supersaturated state (growth relaxation) and an undersaturated state (dissolution relaxation). The concentration for the dissolution relaxation reached to a constant value in a week, which did not coincide with a concentration for the growth relaxation in a comparable period. From a theoretical point of view, we regarded the asymptotic concentration for the dissolution relaxation as the solubility. The molar enthalpy of thermal denaturation of pressurized (1hour at 100 MPa) sample (lysozyme: 5mg/ml) was also measured with a differential scanning microcalorimeter (DSC). The enthalpy was not different from that of non-pressurized sample. Thus, the effect of the irreversible pressure denaturation of lysozyme up to 100 MPa on the results of our experiments was negligible.
• Effects of pressure on growth kinetics of protein crystals

  Y Suzuki, S Miyashita, T Sawada, G Sazaki, T Nakada, H Komatsu, T Arao, K Tamura

  TRENDS IN HIGH PRESSURE BIOSCIENCE AND BIOTECHNOLOGY, PROCEEDINGS 19 123 - 130 0921-0423 2002 [Refereed][Not invited]
   

  Normal growth rates of {110} and {101} faces of tetragonal hen egg-white lysozyme crystals were measured in situ under 0.1, 50, and 100 MPa. The solubilities under high pressure enabled us to evaluate supersaturation under high pressure. We found that both growth rates decreased with pressure under the same supersaturation. This means that the surface growth kinetics depends on pressure significantly. The birth and spread model was applied to understand the pressure effects on the growth kinetics. It was found that the increase in the average ledge surface energy of the two-dimensional nuclei with pressure explained the decrease in the growth rate. The molar enthalpy of thermal denaturation of pressurized (1hour at 100 MPa) sample (lysozyme: 5mg/ml) was also measured with a differential scanning microcalorimeter (DSC). The enthalpy was not different from that of non-pressurized sample. Thus, the effect of the irreversible pressure denaturation of lysozyme up to 100 MPa on the results of our experiments was negligible.
• Effects of pressure on growth kinetics of tetragonal lysozyme crystals (vol 208, pg 638, 2000)

  Y Suzuki, S Miyashita, G Sazaki, T Nakada, T Sawada, H Komatsu

  JOURNAL OF CRYSTAL GROWTH 234 (2-3) 610 - 610 0022-0248 2002/01 [Refereed][Not invited]
  
• Si/multicrystalline-SiGe heterostructure as a candidate for solar cells with high conversion efficiency

  N Usami, T Takahashi, K Fujiwara, T Ujihara, G Sazaki, Y Murakami, K Nakajima

  CONFERENCE RECORD OF THE TWENTY-NINTH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE 2002 247 - 249 2002 [Refereed][Not invited]
   

  We report on growth and. characterizations of Si/multicrystalline-SiGe (mc-SiGe) heterostructure as a promising candidate to surpass multicrystalline-Si solar cells. A 0.5 mum-thick Si thin film was grown on mc-SiGe using a solid-source molecular beam epitaxy system. Spatial distribution of the status-of strain in S! was found to be strongly dependent on the, composition and microstructure of underlying mc-SiGe. Large strain distribution and partial strain relaxation were revealed in Si on mc-SiGe with average Ge composition of 0.72. On the other hand, almost uniformly strained-Si film was grown on mc-SiGe with average Ge composition of 0.30. To avoid introduction of recombination centers at the Si/SiGe interface, it is necessary to avoid strain relaxation by decreasing average Ge composition in mc-SiGe.
• Grain growth of polycrystalline Si thin film for solar cells and its effect on crystal properties

  T Ujihara, E Kanda, K Fujiwara, G Sazaki, N Usami, Y Murakami, K Kitahara, K Nakajima

  CONFERENCE RECORD OF THE TWENTY-NINTH IEEE PHOTOVOLTAIC SPECIALISTS CONFERENCE 2002 1339 - 1342 2002 [Refereed][Not invited]
   

  In this study, in order to inquire into the principle of the fabrication of the poly-Si film via the grain growth process, we clarified the grain growth mechanism of the thin film for the solar cell by investigating temporal change of the grain size distribution. Moreover, this process was explained by a theoretical model taking two- and three- dimensional growth modes into account. In addition, the crystal quality. was evaluated using Raman spectroscopy. The quality was very high comparing with the film prepared by the laser annealing technique.
• Improvement in diffraction maxima in orthorhombic HEWL crystal grown under high magnetic field

  T Sato, Y Yamada, S Saijo, T Hori, R Hirose, N Tanaka, G Sazaki, K Nakajima, N Igarashi, M Tanaka, Y Matsuura

  JOURNAL OF CRYSTAL GROWTH 232 (1-4) 229 - 236 0022-0248 2001/11 [Refereed][Not invited]
   

  Orthorhombic crystals of hen egg-white lysozyme (HEWL) were grown under a homogeneous magnetic field of 10 T (B = 10 T). In the magnetic field, crystals were oriented such that their crystallographic c-axes were parallel to the magnetic field, and gave narrower average rocking widths than those grown under 0 T. Crystal quality was evaluated using the full-width at half-maximum (FWHM) of the rocking curve, and the effects of a magnetic field were examined by comparing FWHM of seven crystals grown at 10 T with an equal number grown at 0 T. FWHM values in (10 0 0), (0 8 0), and (0 0 6) reflections decreased by 25%, 38%, and 32%, respectively, and those of general reflections decreased by 7-45 % in crystals grown under high magnetic field. These results show that a magnetic field of 10 T improved the crystal perfection of the orthorhombic lysozyme crystals. At the same time, the maximum resolution limit of X-ray diffraction increased from 1.33 Angstrom for 0 T to 1.13 Angstrom for 10 T. These facts suggest that the application of magnetic field for crystallization might generally have a striking effect in enhancing the diffraction power of protein crystals. (C) 2001 Elsevier Science B.V. All rights reserved.
• Molecular beam epitaxy of GaAs on nearly lattice-matched SiGe substrates grown by the multicomponent zone-melting method

  N Usami, Y Azuma, T Ujihara, G Sazaki, K Nakajima, Y Yakabe, T Kondo, K Kawaguchi, S Koh, Y Shiraki, BP Zhang, Y Segawa, S Kodama

  SEMICONDUCTOR SCIENCE AND TECHNOLOGY 16 (8) 699 - 703 0268-1242 2001/08 [Refereed][Not invited]
   

  A detailed study of molecular beam epitaxy of GaAs on homemade SiGe substrates has been performed. It was found that the initial migration-enhanced epitaxy process with As prelayer is crucial to obtain high-quality GaAs. By (004) x-ray diffraction, the lattice mismatch between GaAs and SiGe was demonstrated to be reduced compared with the conventional GaAs/Ge heterostructure. Furthermore, narrower halfwidth of the rocking curve and stronger photoluminescence intensity were found for GaAs on SiGe. These results show that SiGe is a promising material as an alternative substrate to Ge to realize exact lattice matching to GaAs for solar cell applications.
• Physical model for the evaluation of solid-liquid interfacial tension in silicon

  T Ujihara, G Sazaki, K Fujiwara, N Usami, K Nakajima

  JOURNAL OF APPLIED PHYSICS 90 (2) 750 - 755 0021-8979 2001/07 [Refereed][Not invited]
   

  We proposed a simple lattice model to describe a solid-liquid interface of silicon based on experimental facts and molecular dynamics simulation results, and evaluated the relationship between the interface structure and the interfacial tension by comparing the model with experimental values. As a result, the entropy was found to give a major contribution to the interfacial tension, and it was revealed that the difference of entropy due to lattice disorder of bulk liquid and interface structure is the dominant factor of the entropy contribution. Moreover, the solid-liquid bond energy, which is crucial to estimate the contribution of the enthalpy, was successfully derived. The present model can be also applied to be the semiconductor material which has a diamond structure or a zinc blende structure. (C) 2001 American Institute of Physics.
• Macrobond analysis of the macro- and micromorphology of monoclinic lysozyme crystal

  H Hondoh, G Sazaki, S Miyashita, SD Durbin, K Nakajima, Y Matsuura

  CRYSTAL GROWTH & DESIGN 1 (4) 327 - 332 1528-7483 2001/07 [Refereed][Not invited]
   

  Intermolecular contacts in crystals of monoclinic form hen egg-white lysozyme were analyzed using the macrobond approach. Both the macroscopic crystal morphology and the microscopic morphology observed by atomic force microscopy were explained well using macrobond energies. The features of the advancing steps of the growing surface were related to the step ledge energies. The hydration enthalpy of dissolution of the crystal was estimated using the macrobond energies and the dissolution enthalpy of the crystal obtained from solubility measurements, and showed good agreement with the reported values obtained from thermodynamic measurements.
• Growth of SixGe1-x (x=0.15) bulk crystal with uniform composition utilizing in situ monitoring of the crystal-solution interface

  N Usami, Y Azuma, T Ujihara, G Sazaki, S Miyashita, Y Murakami, K Nakajima

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 40 (6A) 4141 - 4144 0021-4922 2001/06 [Refereed][Not invited]
   

  A new growth system, which allows in situ monitoring of the crystal-solution interface, was developed and applied to grow SixGe1-x (x = 0.15) bulk crystal with uniform composition by the multicomponent zone-melting method. By utilizing the system, the dynamical change of the growth rate was evaluated from the nonlinear upward shift of the interface as a function of the growth time. Based on the monitoring, an attempt was made to balance the pulling rate of the ampoule with the growth rate of the crystal, which led to the suppression of the upward shift of the growth interface, Consequently, the compositional uniformity of the crystal in the growth direction was markedly improved.
• Growth of SiGe bulk crystal with uniform composition by directly controlling the growth temperature at the crystal-melt inter-face using in situ monitoring system

  Y Azuma, N Usami, T Ujihara, G Sazaki, Y Murakami, S Miyashita, K Fujiwara, K Nakajima

  JOURNAL OF CRYSTAL GROWTH 224 (3-4) 204 - 211 0022-0248 2001/04 [Refereed][Not invited]
   

  A SiGe bulk crystal with uniform composition was successfully fabricated by clarifying and controlling the growth parameters at the crystal-melt interface. An apparatus was developed for the direct in situ observation and precise control of the interface parameters such as the temperature and the position. The dynamical change of the growth rate of a SiGe bulk crystal in a temperature gradient can be known by utilizing the apparatus. The growing crystal was continuously pulled down at the pulling rate balanced to the growth rate to keep the interface temperature constant, which resulted in the excellent uniformity of the grown crystal. Our technique opened the possibility to incorporate multicomponent semiconductor substrates to the semiconductor heterostructure technology. (C) 2001 Published by Elsevier Science B.V.
• Protein crystallization : to what extent crystal growth physics can play a role now

  Sazaki G., Nakajima K.

  Seibutsu Butsuri 一般社団法人 日本生物物理学会 41 S17  2001
• Effects of misfit dislocations and AlN buffer layer on the GaInN/GaN phase diagram of the growth mode

  K Nakajima, T Ujihara, S Miyashita, G Sazaki

  JOURNAL OF APPLIED PHYSICS 89 (1) 146 - 153 0021-8979 2001/01 [Refereed][Not invited]
   

  The thickness-composition phase diagrams of the growth modes were determined for the GaInN-on-GaN (GaInN/GaN) and the GaInN-on-AlN-on-GaN (GaInN/AlN/GaN) structures. For this determination, the strain energy was calculated by considering the stress relaxation due to introduction of misfit dislocations, the surface energy was estimated from bonding enthalpy of the nearest-neighbor bonds on the surface, and the interface energy was estimated by considering both effects of the dangling bonds due to lattice misfit and the abrupt transition of bonding species at the heterointerface. From these phase diagrams, it was found that the layer-by-layer growth such as the Frank-van der Merwe mode was very difficult to obtain for the epitaxial growth of GaInN on GaN when the InN fraction is large. The Volmer-Weber mode is dominant in the phase diagram of the GaInN/GaN structures. The influence of an AlN buffer layer with a larger surface energy was studied by introducing an AlN layer between the GaInN layer and the GaN substrate. It was known that the layer-by-layer growth could be more easily obtained if misfit dislocations were introduced and an AlN layer was used as a buffer. (C) 2001 American Institute of Physics.
• Morphology and solubility of multiple crystal forms of Taka-amylase A

  K Ninomiya, T Yamamoto, T Oheda, K Sato, G Sazaki, Y Matsuura

  JOURNAL OF CRYSTAL GROWTH 222 (1-2) 311 - 316 0022-0248 2001/01 [Refereed][Not invited]
   

  An alpha -amylase originating from a mold Aspergillus oryzae, Taka-amylase A (Mr of 52 kDa, pI of 3.8), has been purified to an electrophoretically single band grade. Crystallization behaviors were investigated using ammonium sulfate and polyethleneglycol 8000 as precipitants. The variations in the morphology of the crystals obtained with changing crystallization parameters are described. Five apparently different crystal forms were obtained, and their morphology and crystallographic data have been determined. Solubility values of four typical forms were measured using a Michelson-type two-beam interferometer. The results of these experiments showed that this protein can be a potentially interesting and useful model for crystal growth study with a gram-amount availability of pure protein sample. (C) 2001 Elsevier Science B.V. All rights reserved.
• Phase diagram calculation for epitaxial growth of GaInAs on InP considering the surface, interfacial and strain energies

  K Nakajima, T Ujihara, G Sazaki, N Usami

  JOURNAL OF CRYSTAL GROWTH 220 (4) 413 - 424 0022-0248 2000/12 [Refereed][Not invited]
   

  In order to know the effects of the surface, interfacial and strain energies on the calculation of the phase diagram, these energies were calculated for the GaxIn1-xAs/InP structure and the Ga-In-As ternary phase diagram for the epitaxial growth of GaInAs on (111) InP was determined. The layer-thickness dependence of the liquidus temperature and solidus composition was determined. It was found that the liquidus and solidus phases were strongly influenced by these energies when the layer thickness was thinner than about 0.06 mum. The consideration of the effects of the surface, interfacial and strain energies is effective to explain the peculiar behavior of the experimental results near the lattice-matched composition (x = 0.47), which is called the latching effect. (C) 2000 Elsevier Science B.V. All rights reserved.
• SiGe bulk crystal as a lattice-matched substrate to GaAs for solar cell applications

  N Usami, Y Azuma, T Ujihara, G Sazaki, K Nakajima, Y Yakabe, T Kondo, S Koh, Y Shiraki, B Zhang, Y Segawa, S Kodama

  APPLIED PHYSICS LETTERS 77 (22) 3565 - 3567 0003-6951 2000/11 [Refereed][Not invited]
   

  SiGe bulk crystal fabricated by a multicomponent zone-melting method was used as a substrate for epitaxial growth of GaAs. Compared with conventional GaAs/Ge heterostructure, the lattice mismatch of GaAs/Si0.022Ge0.978 was confirmed to be reduced by a decrease of the peak separation of (400) x-ray diffraction from the epitaxial GaAs layer and the substrate. Furthermore, the linewidth of the rocking curve of GaAs on SiGe was found to be narrower than that of GaAs on Ge. These results show that SiGe is promising material as an alternative substrate to Ge for realization of exactly lattice-matched GaAs/SiGe solar cells. (C) 2000 American Institute of Physics. [S0003-6951(00)01249-3].
• In situ measurement of composition in high-temperature solutions by X-ray fluorescence spectrometry

  T Ujihara, G Sazaki, S Miyashita, N Usami, K Nakajima

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS 39 (10) 5981 - 5982 0021-4922 2000/10 [Refereed][Not invited]
   

  We proposed an ill situ technique based on X-ray fluorescence spectrometry to measure the composition of a high-temperature solution in a crucible. The sample holder for this technique was composed of carbon, which is transparent to X-rays. Using the present technique, equilibrium compositions of zinc in a gallium solution were measured. The results agreed well with the liquidus curve of the Ga-Zn phase diagram, and thus the validity of this technique was proved.
• Enhancement in the perfection of orthorhombic lysozyme crystals grown in a high magnetic field (10 T)

  T Sato, Y Yamada, S Saijo, T Hori, R Hirose, N Tanaka, G Sazaki, K Nakajima, N Igarashi, M Tanaka, Y Matsuura

  ACTA CRYSTALLOGRAPHICA SECTION D-BIOLOGICAL CRYSTALLOGRAPHY 56 1079 - 1083 0907-4449 2000/08 [Refereed][Not invited]
   

  Orthorhombic crystals of hen egg-white (HEW) lysozyme were grown in a homogeneous and static magnetic field of 10 T. All crystals grown at 10 T were oriented such that their crystallographic c axes were parallel to the magnetic field direction and showed a narrower average full-width at half-maximum (FWHM) of the rocking curve than those grown at 0 T. Rocking-width measurements were made at the BL-10A station at the Photon Factory, Tsukuba, Japan, using a high-resolution vertical-type four-circle diffractometer. Crystal perfection was evaluated using the FWHM of the rocking curve; the effects of the magnetic field on the quality of the crystals were examined by comparison of the FWHM of seven crystals grown at 10 and 0 T. The FWHMs of the reflections along the a, b and c axes decreased by 23.5, 35.3 and 27.8%, respectively, and those of other general reflections decreased by 17.4-42.2% in the crystals grown at high magnetic field. These results clearly showed that a magnetic field of 10 T improved the crystal perfection of the orthorhombic lysozyme crystals. As a result, the maximum resolution of X-ray diffraction increased from 1.3 Angstrom at 0 T to 1.13 Angstrom at 10 T. The magnetic field also affected the dimensions of the unit cell, increments being 0.2% for the a and c axes and 0.1% for the b axis, respectively. These facts suggest that the application of a high magnetic field during crystallization might result in remarkable enhancements in the diffraction power of protein crystals having magnetic anisotropy.
• Thickness dependence of stable structure of the Stranski-Krastanov mode in the GaPSb/GaP system

  K Nakajima, T Ujihara, S Miyashita, G Sazaki

  JOURNAL OF CRYSTAL GROWTH 209 (4) 637 - 647 0022-0248 2000/02 [Refereed][Not invited]
   

  Many types of structure of the SK mode have possibility to appear as the crystal grows. In order to understand the most stable structure for the SK mode and the minimum-energy path through which the SK mode structure with the smallest free energy appears at each layer-thickness, the strain, surface, and interfacial energies of the GaPSb/GaP system were calculated for the FM, VW and several types of SK mode structures. The free energy for each structure was derived from these energies. By comparison of the free energies of the several types of the SK structure, it is found that the most stable structure of the SK mode is a cluster with four lattice layers or minimum thickness on a wetting layer whose lattice layer increases. As the crystal grows in the SK mode, the path on which only the wetting layer becomes thicker is the most stable. The path on which only the cluster on the wetting layer becomes larger is the most unstable. The thickness-composition phase diagrams for the FM, SKj (j = 1-2) and VW modes were determined for the GaPSb/GaP(1 1 1) system. The area of the SKj region becomes smaller as the cluster height j increases, and that of the VW region becomes larger. In order to compare these phase diagrams, the phase diagram for the case of the SK mode structure whose wetting layer is always one lattice layer thick was determined, and the phase diagram for the SKI mode was also determined by considering the reconstruction of dangling bonds for the calculation of the surface energy. (C) 2000 Elsevier Science B.V. All rights reserved.
• An interferometric study of the solubility of lysozyme crystals under high pressure

  Y Suzuki, T Sawada, S Miyashita, H Komatsu, G Sazaki, T Nakada

  JOURNAL OF CRYSTAL GROWTH 209 (4) 1018 - 1022 0022-0248 2000/02 [Refereed][Not invited]
   

  The effect of hydrostatic pressure on the solubility of tetragonal hen egg-white lysozyme crystals was measured in situ by a two-beam interferometer combined with a high-pressure optical cell which was newly designed by our group. The change in the concentration with time during equilibration was measured accurately and continuously starting from a supersaturated state (growth relaxation) and an undersaturated state (dissolution relaxation). The solubility value thus measured at 100 MPa was 28% larger than that at 0.1 MPa, and this increase was much smaller than those of previous reports. (C) 2000 Elsevier Science B.V. All rights reserved.
• Effects of a magnetic field on the growth rate of tetragonal lysozyme crystals

  S Yanagiya, G Sazaki, SD Durbin, S Miyashita, K Nakajima, H Komatsu, K Watanabe, M Motokawa

  JOURNAL OF CRYSTAL GROWTH 208 (1-4) 645 - 650 0022-0248 2000/01 [Refereed][Not invited]
   

  The growth process of tetragonal lysozyme crystals under static and homogeneous magnetic field of 11 T was observed in situ by using an optical microscope which was specially designed and prepared. This optical system, having a spatial resolution of 0.5 mu m, was used to measure the growth rate of the lysozyme crystals under 0 and 11 T. The effect of the magnetic field of 11 T was to decrease the growth rate of the crystals. The effect of a magnetic field on the dissolution process of the crystal was also investigated. (C) 2000 Elsevier Science B.V. All rights reserved.
• Effects of pressure on growth kinetics of tetragonal lysozyme crystals

  Y Suzuki, S Miyashita, G Sazaki, T Nakada, T Sawada, H Komatsu

  JOURNAL OF CRYSTAL GROWTH 208 (1-4) 638 - 644 0022-0248 2000/01 [Refereed][Not invited]
   

  Growth kinetics of tetragonal hen egg-white lysozyme crystals under high pressures was studied by in situ measurements. Normal growth rates of {1 1 0} and {1 0 1} faces were measured under 0.1, 50, and 100 MPa. The solubilities under high pressure enabled us to evaluate supersaturation under high pressure. We found that both growth rates decreased with pressure under the same supersaturation. This means that the surface growth kinetics significantly depends on pressure. The birth and spread model was applied to understand the pressure effects on the growth kinetics. It was found that the increase in the average ledge surface energy of the two-dimensional nuclei with pressure explained the decrease in the growth rare. (C) 2000 Elsevier Science B.V. All rights reserved.
• Effects of the dislocation density and surface energy on phase diagrams of the S-K growth mode for the GaInN/GaN and GaPSb/GaP systems

  K Nakajima, T Ujihara, S Miyashita, G Sazaki

  MORPHOLOGICAL AND COMPOSITIONAL EVOLUTION OF HETEROEPITAXIAL SEMICONDUCTOR THIN FILMS 618 285 - 290 0272-9172 2000 [Refereed][Not invited]
   

  The growth of thin films has been categorized into three types namely the Frank-van der Merwe (PM) mode, the Stranski-Krastanov (SK) mode, and the Volmer-Weber (VW) mode. The strain, surface, and interfacial energies were calculated for the three types of growth mode of the GaInN/GaN and GaPSb/GaP systems by considering the effects of the dislocation density and reconstruction of dangling bonds. The phase diagrams of the growth modes were determined for the GaInN/GaN and GaPSb/GaP systems. In the GaInN/GaN system, the VW mode appears in the most region of the phase diagram. The region of the VW mode becomes smaller as the dislocation density increases. In the GaPSb/GaP system, the SK and VW modes appear and the region of these modes becomes larger as the reconstruction ratio increases.
• Growth of Y2Cu2O5 single crystals by the traveling solvent floating zone method

  Y Nishimura, Y Matsuoka, S Miyashita, H Komatsu, M Motokawa, T Nakada, G Sazaki

  JOURNAL OF CRYSTAL GROWTH 207 (3) 206 - 213 0022-0248 1999/12 [Refereed][Not invited]
   

  Sufficiently large single crystals of Y2Cu2O5 for use in neutron diffraction experiments were successfully grown by the traveling-solvent floating zone method under an oxygen partial pressure of 40-100%. The optimum composition for growth from a high-temperature solution was determined in situ using high-temperature optical microscopy. The growth direction was parallel to the crystallographic b-axis. This crystal exhibited well-defined metamagnetic transitions. (C) 1999 Elsevier Science B.V. All rights reserved.
• New growth method of oxide crystals by PO2 change applied to SmBa2Cu3Ox single crystals

  Y Nishimura, S Miyashita, SD Durbin, T Nakada, G Sazaki, H Komatsu

  JOURNAL OF CRYSTAL GROWTH 205 (4) 503 - 509 0022-0248 1999/09 [Refereed][Not invited]
   

  Reliable liquidus lines of SmBa2Cu3Ox in the SmBa2Cu3Ox-Ba7Cu18O25 system under various oxygen partial pressures were determined precisely by in situ observation. The dependence of the liquidus line on oxygen partial pressure was revealed: as the oxygen partial pressure increased, the liquidus shifted to higher temperature. Using this data, SmBa2Cu3Ox crystals were grown. This process was successfully observed in situ by high-temperature optical microscopy. (C) 1999 Elsevier Science B.V. All rights reserved.
• Growth of Ge-rich SixGe1-x single crystal with uniform composition (x=0.02) on a compositionally graded crystal for use as GaAs solar cells

  K Nakajima, S Kodama, S Miyashita, G Sazaki, S Hiyamizu

  JOURNAL OF CRYSTAL GROWTH 205 (3) 270 - 276 0022-0248 1999/08 [Refereed][Not invited]
   

  An improved growth technology was developed to grow Ge-rich SiGe crystals on Ge seeds on the basis of the Multi-component zone melting method. The purpose of growing such a crystal is the preparation of exactly lattice-matched GaAs/SiGe heterostructures for higher-efficiency tandem cells than GaAs/Ge cells. In this method, Si solute elements are continuously supplied from the Si source crystal, and the compositional profile in the SiGe crystal is controlled by the pulling rate. We were successful in preparing a SixGe1-x single crystal with a uniform composition (x = 0.02) following a graded composition (from x = 0 to 0.02). The size of the uniform crystal is 2 cm in length and 1.5 cm in diameter. The combined structure of uniform SiGe/graded SiGe/Ge has two expected merits. A lattice-matched GaAs epitaxial layer can be grown on the SiGe uniform crystal, and the graded composition from Ge (x = 0) to uniform SiGe (x = 0.02) widens the range of absorbed wavelengths of the solar spectrum. (C) 1999 Elsevier Science B.V. All rights reserved.
• Magnetic damping of the temperature-driven convection in NaCl aqueous solution using a static and homogeneous field of 10 T

  G Sazaki, SD Durbin, S Miyashita, T Ujihara, K Nakajima, M Motokawa

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS 38 (7B) L842 - L844 0021-4922 1999/07 [Refereed][Not invited]
   

  Temperature-driven convection in 25 w% NaCl aqueous solution was observed in situ under a static and homogeneous magnetic field of 10 T. The convection in the solution was visualized using polystyrene latex particles of 5 mu m diameter. A magnetic field of 10 T reduced the velocity of convection by a factor of two. Magnetic damping of convection in an electrolyte solution could be a useful technique to control the growth of crystals such as proteins.
• Phase diagrams and stable structures for Sranski-Krastanov mode of III-V ternary quantum dots

  K. Nakajima, T. Ujihara, S. Miyashita, G. Sazaki

  Journal of Korean Association of Crystal Growth 9 387-395  1999 [Refereed][Not invited]
  
• Effect of a magnetic field on the orientation of hen egg-white lysozyme crystals

  S Yanagiya, G Sazaki, SD Durbin, S Miyashita, T Nakada, H Komatsu, K Watanabe, M Motokawa

  JOURNAL OF CRYSTAL GROWTH 196 (2-4) 319 - 324 0022-0248 1999/01 [Refereed][Not invited]
   

  Recent experiments have shown that lysozyme crystallization in a magnetic field of the order of 1 T can result in a significant degree of orientation of the crystals. We present more extensive experimental results and propose a model to account for this phenomenon. Because of the small susceptibility anisotropy of most protein molecules, the orienting effect is unimportant for smaller aggregates, even those much larger than a critical nucleus. However, during sedimentation crystals grow larger and are more likely to become aligned. The degree of orientation thus depends on crystal growth rate and container geometry, in addition to magnetic field strength, as we have confirmed experimentally. (C) 1999 Elsevier Science B.V. All rights reserved.
• Incorporation of impurity to a tetragonal lysozyme crystal

  K Kurihara, S Miyashita, G Sazaki, T Nakada, SD Durbin, H Komatsu, T Ohba, K Ohki

  JOURNAL OF CRYSTAL GROWTH 196 (2-4) 285 - 290 0022-0248 1999/01 [Refereed][Not invited]
   

  Concentration of a phosphor-labeled impurity (ovalbumin) incorporated into protein (hen egg white lysozyme) crystals during growth was measured by fluorescence. This technique enabled us to measure the local impurity concentration in a crystal quantitatively. Impurity concentration increased with growth rate, which could not be explained by two conventional models (equilibrium adsorption model and Burton-Prim-Slichter model); a modified model is proposed. Impurity concentration also increased with the pH of the solution. This result is discussed considering the electrostatic interaction between the impurity and the crystallizing species. (C) 1999 Elsevier Science B.V. All rights reserved.
• Solubility of tetragonal and orthorhombic lysozyme crystals under high pressure

  G Sazaki, Y Nagatoshi, Y Suzuki, SD Durbin, S Miyashita, T Nakada, H Komatsu

  JOURNAL OF CRYSTAL GROWTH 196 (2-4) 204 - 209 0022-0248 1999/01 [Refereed][Not invited]
   

  Two-beam interferometry was applied to measure lysozyme solubility under high pressure. This rapid method allowed determination of one data point within 3 h. The solubility of tetragonal lysozyme crystals was determined as a function of temperature at 0.1? 50, and 100 MPa, and that of orthorhombic crystals was measured at 0.1 and 100 MPa. The solubility of tetragonal crystals increased with pressure; however, that of orthorhombic crystals decreased. In both cases, the enthalpy and entropy of dissolution decreased with pressure. (C) 1999 Elsevier Science B.V. All rights reserved.
• Direct AFM observations of impurity effects on a lysozyme crystal

  T Nakada, G Sazaki, S Miyashita, SD Durbin, H Komatsu

  JOURNAL OF CRYSTAL GROWTH 196 (2-4) 503 - 510 0022-0248 1999/01 [Refereed][Not invited]
   

  Impurity effects on the growth of tetragonal lysozyme crystals have been studied using in situ atomic force microscopy. Commercially available hen egg white lysozyme was characterized by sodium dodecyl sulfate polyacrylamide gel electrophoresis with silver staining, and purified by re-crystallization and successive high pressure liquid chromatography. On the (1 1 0) crystal surface, there was no significant difference in morphology between crystals grown in commercial and in purified solutions. On the (1 0 1) surface, however, a large number of small particles were found when the crystal was grown in the commercial solution, while the surface grown in the purified solution was quite smooth. Among the typical residual impurities contained in commercial lysozyme, only covalently bound lysozyme dimer yielded such particles. From measurements of particle separation and an estimate of the critical nucleation size, we infer that the particles reduced the step velocity according to the mechanism described by Cabrera et al. [N. Cabrera, D.A. Vermilyea, in: R.H. Doremus et al. (Eds.) Growth and Perfection of Crystals, 1958, p. 393]. (C) 1999 Elsevier Science B.V. All rights reserved.
• Crystallization studies on a concanavalin A crystal with high-index faces

  E Kashimoto, G Sazaki, K Hasegawa, T Nakada, S Miyashita, H Komatsu, K Sato, Y Matsuura, H Tanaka

  JOURNAL OF CRYSTAL GROWTH 186 (3) 461 - 470 0022-0248 1998/03 [Refereed][Not invited]
   

  Well-faceted crystals of concanavalin A were obtained in two different morphologies. Prior to the crystallization, concanavalin A was homogeneously metallized with Mn2+ and Ca2+ cations, Using the metallized samples, we measured the solubility of a well-faceted crystal. The as-grown crystal was bounded by flat faces with high Miller indices. We measured the normal growth rate (R) of these flat faces with respect to the supersaturation (sigma). The R-sigma relation showed that the growth mode corresponded to two-dimensional nucleation growth of a birth and spread type. (C) 1998 Elsevier Science B.V. All rights reserved.
• Concentration Field around a Growing Crystal under Microgravity

  MIYASHITA Satoru, KURIHARA Kazuo, HASEGAWA Kazuhiro, SAZAKI Gen, NAKADA Toshitaka, Stephen D. Durbin, KOMATSU Hiroshi, FUJISHIMA Motoi, KOYAMA Masato

  International Journal of Microgravity Science and Application 15 (Supplement II) 577 - 581 1998 [Refereed][Not invited]
  
• Effects of a magnetic field on the nucleation and growth of protein crystals

  G Sazaki, E Yoshida, H Komatsu, T Nakada, S Miyashita, K Watanabe

  JOURNAL OF CRYSTAL GROWTH 173 (1-2) 231 - 234 0022-0248 1997/03 [Refereed][Not invited]
   

  Crystallization of hen egg-white lysozyme and horse-spleen ferritin was carried out under a steady and uniform magnetic field of 10 T and compared with the crystals grown under 0 T. It is clearly demonstrated that a magnetic field reduced the number of nuclei and not only oriented the crystals but also modified the habit of protein crystals. The present experimental result indicates that application of a magnetic field is an efficient method for growing a small number of large crystals.
• In-situ Observation of Oxidation Process on Au(111) Electrode by Atomic Force Microscopy.

  Nakda Toshitaka, Nishizawa Tsuyoshi, Sazaki Gen, Miyashita Satoru, Komatsu Hiroshi

  Butsuri 一般社団法人 日本物理学会 52 (2) 114 - 117 0029-0181 1997
• In Situ Observation of the Concentration Distribution around a Lysozyme Crystal by Two-beam Interferometry

  SAZAKI Gen, KURIHARA Kazuo, MIYASHITA Satoru, KOMATSU Hiroshi, NAKADA Toshitaka

  Journal of the Japanese Association of Crystal Growth 日本結晶成長学会 23 (5) 413 - 421 0385-6275 1996/12 [Refereed][Not invited]
   

  The bottle neck of a three-dimensional structural analysis of protein molecules is the crystallization of large (>0.1μm) and suitable high quality crystals. To overcome this difficulty, the growth process of protein crystals, such as the mass transfer of the molecules and the growth kinetics of the crystals, must be quantitatively analyzed. Two-beam interferometry is a powerful technique for an in situ observation of the concentration distribution around a growing crystal. By using interferometer of Michelson type, we have been successfully observed the concentration distribution around a hen egg-white lysozyme crystal. Here, we outline the principle of two-beam interferometry, and explain how the growth mode and the diffusion coefficient of lysozyme molecules can be obtained. We also show a rapid solubility measurement of protein crystals by using the same interferometric technique, which can determine the solubility of lysozyme crystals at one point in a phase diagram within 1-2 hrs. This technique is about ten times quicker than other ordinary methods so far used for a solubility measurement.
• AFM observation of a sulfate adlayer on Au(111) in sulfuric acid solution

  T Nishizawa, T Nakada, Y Kinoshita, S Miyashita, G Sazaki, H Komatsu

  SURFACE SCIENCE 367 (3) L73 - L78 0039-6028 1996/12 [Refereed][Not invited]
   

  In situ atomic force microscopy (AFM) has been applied to study the structure of the Au(111) in sulfuric acid solution. Above 0.88 V versus Ag/AgCl, the Au(111) surface was observed to form an ordered structure having (2/1 1/2) periodicity of the structure agrees with the previous STM experiments, the corrugation of the AFM image was different to the STM images. The AFM image indicates that sulfate anions adsorb on the Au(111) surface with C-2v symmetry.
• A novel approach to the solubility measurement of protein crystals by two-beam interferometry

  G Sazaki, K Kurihara, T Nakada, S Miyashita, H Komatsu

  JOURNAL OF CRYSTAL GROWTH 169 (2) 355 - 360 0022-0248 1996/11 [Refereed][Not invited]
   

  A novel technique was developed for the rapid solubility measurement of protein crystals (lysozyme) by two-beam interferometry. The merits of this technique are: (1) time saving (less than 2 h to obtain one experimental point), (2) the small amount of the sample (similar to 66 mu l), (3) high accuracy, (4) applicable to the solubility measurement of a metastable phase and (5) insensitive to impurities. The limitations of the present technique are also discussed.
• Interferometric study on the crystal growth of tetragonal lysozyme crystal

  K Kurihara, S Miyashita, G Sazaki, T Nakada, Y Suzuki, H Komatsu

  JOURNAL OF CRYSTAL GROWTH 166 (1-4) 904 - 908 0022-0248 1996/09 [Refereed][Not invited]
   

  Using a Michelson interferometer, the concentration-gradient layers around a growing hen-egg-white lysozyme, tetragonal crystal were observed. By measuring by concentration distribution and the normal growth rate, the growth mode and the diffusion coefficient of lysozyme molecules were evaluated. The experimental results indicate that the growth is regulated by two-dimensional nucleation in the supersaturation range of 6 less than or equal to sigma(surf) less than or equal to 20. The diffusion coefficient was nearly constant, 4.9 +/- 0.7 x 10(-11) m(2) s(-1) over a wide supersaturation range, differing from that of supersaturated bulk solutions.
• Atomic force microscopic study of subsurface ordering and structural transforms in n-alcohol on mica and graphite

  T Nakada, S Miyashita, G Sazaki, H Komatsu, AA Chernov

  JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS 35 (1A) L52 - L55 0021-4922 1996/01 [Refereed][Not invited]
   

  Structure forces in n-alcohols (CnH2n+1OH (8 less than or equal to n less than or equal to 12)) on the mica or graphite surfaces were investigated using an atomic force microscope (AFM). The structure force on graphite has a periodicity of similar to 0.5 nm, which is independent of temperature. The structure force on mica has a periodicity of 0.86 nm when T < 40 degrees C which increases linearly with n in the range 1.7 to 2.3 nm when T > 40 degrees C. This phase transition corresponds to a change in the alignment of molecules on the surface from parallel (lying, at T < 40 degrees C) to normal (standing, at T > 40 degrees C).
• Effect of self-degradation products on crystallization of protease thermolysin

  Gen Sazaki, Satoshi Aoki, Hiroshi Ooshima, Jyoji Kato

  Journal of Crystal Growth 139 (1-2) 95 - 103 0022-0248 1994/05/01 [Refereed][Not invited]
   

  The effect of self-degradation products of protease thermolysin on the crystallization of thermolysin was investigated. Crystallizations were carried out at the concentration of the self-degradation products of 0 to 0.622 mg/ml, 5°C and pH 7.0. The initial concentration of thermolysin was constant (1.70 ± 0.01 mg/ml). Crystallizations were monitored by dynamic light scattering and photomicroscopy. The crystallization of thermolysin in the presence of the self-degradation products proceeded through two successive steps: the formation of primary particles and the formation of large crystals by the aggregation of the primary particles. Low concentration of the self-degradation products (0.212 mg/ml) accelerated the formation of the primary particles and also the formation of the large crystals. High concentration of the self-degradation products, however, inhibited the formation of the primary particles and their aggregation to the large crystals. As the result, a large number of small aggregates which had not grown to the large crystals were observed by photomicroscopy. An analysis of the crystals and the primary particles formed in the presence of the self-degradation products by gel filtration high performance liquid chromatography revealed that the self-degradation products are not incorporated in the primary particles, but are incorporated probably in the openings between the primary particles during the crystallization. © 1994.
• EFFECT OF SUPERSATURATION RATIO ON THE GROWTH-RATE AND NUMBER OF PROTEASE THERMOLYSIN CRYSTALS

  G SAZAKI, H OOSHIMA, J KATO

  JOURNAL OF CRYSTAL GROWTH 135 (1-2) 199 - 208 0022-0248 1994/01 [Refereed][Not invited]
   

  The effect of initial supersaturation ratio on the growth rate and number of protease thermolysin crystals was investigated at the initial supersaturation ratio of 8.9 to 17.9 and pH 7.0. The average diameter and number of thermolysin crystals were measured by dynamic light scattering during crystallization. The crystallization of thermolysin proceeded through two successive steps: the formation of primary particles and the formation of large crystals from the primary particles. The size of the primary particles was not affected by the initial supersaturation ratio and was about 60 nm in diameter. The growth rate of thermolysin crystals had a maximum at the initial supersaturation ratio of 9.5. On the other hand, the number of thermolysin crystals decreased with an increase of the initial supersaturation ratio, and turned to increase through a minimum at the initial supersaturation ratio of 13.4. The dependencies of the size and number of thermolysin crystals on the initial supersaturation ratio were explained hy the successive two step mechanism of crystallization.
• Mechanism of crystallization of enzyme protein thermolysin

  Gen Sazaki, Hiroshi Ooshima, Jyoji Kato, Yoshio Harano, Norio Hirokawa

  Journal of Crystal Growth 130 (3-4) 357 - 367 0022-0248 1993 [Refereed][Not invited]
   

  The mechanism of crystallization of enzyme protein thermolysin was investigated. The size distribution of thermolysin precipitates was measured by dynamic light scattering during precipitation, and the surface and cross section of the finally obtained precipitate were observed by scanning electron microscopy. The thermolysin precipitates obtained at the initial supersaturation ratio of 8.9 to 164 and pH 7.0 were hexagonal rods having an average size of 9.2×1.5 μm, and were composed of a number of small particles of 15 to 200 nm in diameter. The average size of the small particles was 60 nm in diameter, and the formation of the particles was found to be completed in the early stage of precipitation. Observation of the finally recovered thermolysin precipitate by polarizing microscopy revealed that the precipitate is a crystalline solid. From these data, a possible mechanism of thermolysin crystallization was proposed. The crystallization proceeds through two steps: the first step is the formation of primary particles, and the second step is crystal growth by highly ordered aggregation of the primary particles. © 1993.

Books etc

• 図説 表面分析ハンドブック

  日本表面真空学会 (Joint work微分干渉顕微鏡・位相差顕微鏡, pp. 220-223)
  朝倉書店 2021/06 (ISBN: 4254201702) 558
• 有機・無機材料の相転移ダイナミクス : 数理から未来のマテリアル開発まで

  日本化学会 (Joint work氷結晶の相転移ダイナミクスを見る, pp.58-66)
  化学同人 2020/03 (ISBN: 9784759813951) vi, 194p, 図版 [4] p
• Compendium of surface and interface analysis

  The Surface Science Society of Japan (Joint workChapter 10. Differential interference contrast microscopy/phase-contrast microscopy, pp.55-60)
  Springer 2018/03 (ISBN: 9789811061554) xvi, 853 p.
• 低温環境の科学事典

  河村, 公隆 (Joint work第11-7項 表面融解, pp.368-369)
  朝倉書店 2016/07 (ISBN: 9784254161281) xii, 411p, 図版 [8] p
• 低温科学便覧 = Handbook of low temperature science

  北海道大学低温科学研究所 (Joint work第2章 氷および雪の結晶成長, pp. 11-49)
  丸善出版 2015/10 (ISBN: 9784621089644) xvii, 383p
• Solid-solid interfaces and thin films

  Wandelt, K. (Klaus) (Joint workChapter 17 Surface of Ice, pp. 305-348)
  Wiley-VCH 2014 (ISBN: 9783527411573) xxviii, p. 421-974
• Physics and Chemistry of Ice, 2010

  Yoshinori Furukawa, Gen Sazaki, Tsutomu Uchida, Naoki, Watanabe (Compilation)
  Hokkaido University Press 2011 (ISBN: 9784832903616) xi, 472 p.
• タンパク質結晶の新展開 : 新しい育成技術から構造解析・応用研究へ

  高野, 和文 (Joint work第II編第5章2節 圧力, pp.89-96 および第II編第8章 成長観察・評価, pp.142-154)
  シーエムシー出版 2008/05 (ISBN: 9784781300245) ix, 326p

MISC

• In-situ optical microscopy observation of elementary steps on ice crystals grown in vapor and their growth kinetics

  Gen Sazaki, Masahiro Inomata, Harutoshi Asakawa, Etsuro Yokoyama, Shunichi Nakatsubo, Ken-ichiro Murata, Ken Nagashima, Yoshinori Furukawa  PROGRESS IN CRYSTAL GROWTH AND CHARACTERIZATION OF MATERIALS  67-  (4)  2021/11  

  Ice is one of the most abundant materials on the earth's surface, and its growth governs various natural phenomena. Hence, the molecular-level understanding of ice crystal surfaces is crucially important. However, it is generally acknowledged that the molecular-level observation of ice crystal surfaces by ordinary microscopy techniques, such as atomic force microscopy and scanning electron microscopy, is very difficult at temperatures near the melting point (0 degrees C). To overcome such difficulties, we have developed laser confocal microscopy combined with differential interference contrast microscopy (LCM-DIM). We proved that LCM-DIM can visualize individual elementary steps (0.37 nm in thickness) on a basal face by observing two-dimensional nucleation growth. Then we found by LCM-DIM that spiral steps on a basal face exhibit a double-spiral pattern, which can be expected from ice's crystallographic structure. In addition, we revealed that temperature dependence of growth kinetics of elementary spiral steps on a basal face exhibits complicated behaviors, which show the presence of unknown phenomena in the growth kinetics. Furthermore, we proved that surface diffusion of water admolecules on a basal face plays a crucially important role in the lateral growth of elementary steps when the distance between adjacent spiral steps is smaller than 15 mu m. These findings will provide a clue for unlocking growth kinetics of ice crystals. In addition, through the use of LCM-DIM much progress has been made in studies on the surface melting of ice and the interaction between ice and atmospheric gasses.
• 第16回結晶成長国際サマースクール(ISSCG-16)報告 (第18回結晶成長国際会議(ICCGE-18) 第16回結晶成長国際サマースクール(ISSGE-16)特別号)

  佐﨑 元, 灘 浩樹, 成塚 重弥, 長嶋 剣, 川野 潤, 大鉢 忠, 柿本 浩一  日本結晶成長学会誌 = Journal of the Japanese Association for Crystal Growth  43-  (5)  277  -284  2016  [Not refereed][Not invited]
  
• 氷結晶表面で生成する2種類の擬似液体層の安定性

  麻川明俊, 佐崎元, 村田憲一郎, 長嶋剣, 中坪俊一, 古川義純  日本物理学会講演概要集(CD-ROM)  70-  (1)  2015
• 氷プリズム面及び高指数面上で2種類の擬似液体層は現れるのか?

  麻川明俊, 佐崎元, 村田憲一郎, 長嶋剣, 中坪俊一, 古川義純  応用物理・物理系学会中国四国支部合同学術講演会講演予稿集  2015-  2015
• 氷結晶の自励振動成長―国際宇宙ステーション実験の概要―

  FURUKAWA YOSHINORI, NAGASHIMA KEN, ASAKAWA HARUTOSHI, NAKATSUBO SHUN'ICHI, MURATA KEN'ICHIRO, SAZAKI GEN, YOSHIZAKI IZUMI, TAMARU HARUKA, SHIMAOKA TARO, SONE TAKEHIKO, MAKI TAKAO, YAMAMOTO ASUKA  結晶成長国内会議予稿集(CD-ROM)  44th-  ROMBUNNO.07AC02  2014/11/06  [Not refereed][Not invited]
  
• 氷ベーサル面の成長に与える塩化水素ガスの効果

  NAGASHIMA KEN, SAZAKI GEN, HAMA TETSUYA, ASAKAWA HARUTOSHI, MURATA KEN'ICHIRO, NAKATSUBO SHUN'ICHI, FURUKAWA YOSHINORI  結晶成長国内会議予稿集(CD-ROM)  44th-  ROMBUNNO.07AC03  2014/11/06  [Not refereed][Not invited]
  
• 氷プリズム面上での2種類の擬似液体層の生成過程

  ASAKAWA HARUTOSHI, SAZAKI GEN, MURATA KEN'ICHIRO, NAGASHIMA KEN, NAKATSUBO SHUN'ICHI, FURUKAWA YOSHINORI  結晶成長国内会議予稿集(CD-ROM)  44th-  ROMBUNNO.07AC04  2014/11/06  [Not refereed][Not invited]
  
• Optical In-situ Observation of Crystal Surfaces(The Memory of The Late Professor Ichiro Sunagawa)

  Sazaki Gen  Journal of the Japanese Association of Crystal Growth  41-  (1)  27  -27  2014/04
• 30aAQ-2 Generation mechanisms and thermodynamic stability of quasi-liquid layers on ice basal faces

  Sazaki Gen, Asakawa Harutoshi, Nagashima Ken, Nakatsubo Syunichi, Furukawa Yoshinori  Meeting abstracts of the Physical Society of Japan  69-  (1)  902  -902  2014/03/05
• 氷結晶表面の擬似液体層の生成機構と熱力学的安定性

  SAZAKI GEN, ASAKAWA HARUTOSHI, NAGASHIMA KEN, NAKATSUBO SHUN'ICHI, FURUKAWA YOSHINORI  日本物理学会講演概要集  69-  (1)  357  2014/03/05  [Not refereed][Not invited]
  
• 気相から成長する氷結晶の単位ステップの成長カイネティクス

  ASAKAWA HARUTOSHI, SAZAKI GEN, YOKOYAMA ETSURO, NAGASHIMA KEN, NAKATSUBO SHUN'ICHI, FURUKAWA YOSHINORI  日本物理学会講演概要集  69-  (1)  897  2014/03/05  [Not refereed][Not invited]
  
• Special Issue : The Memory of The Late Professor Ichiro Sunagawa

  塚本 勝男, 佐﨑 元  日本結晶成長学会誌 Journal of the Japanese Association for Crystal Growth  41-  (1)  1  -36  2014
• Report on the 15th International Summer School on Crystal Growth(News of JACG)

  Sazaki Gen  Journal of the Japanese Association of Crystal Growth  40-  (3)  193  -194  2013/10
• 氷ベーサル面上での渦巻ステップの構造について

  SAZAKI GEN, ASAKAWA HARUTOSHI, NAGASHIMA KEN, NAKATSUBO SHUN'ICHI, FURUKAWA YOSHINORI  日本物理学会講演概要集  68-  (2)  787  2013/08/26  [Not refereed][Not invited]
  
• The Forefront of Protein Crystal Growth

  SAZAKI Gen, UENO Satoru  Journal of the Japanese Association of Crystal Growth  40-  (2)  71  -71  2013/07/31
• Pressure Effects on Crystal Growth of Proteins

  SUZUKI Yoshihia, SAZAKI Gen, FUJIWARA Takahisa, TSUKAMOTO Masayuki  Journal of the Japanese Association of Crystal Growth  40-  (2)  107  -114  2013/07/31  

  Pressure is an attractive thermodynamic parameter. In this review, I present the great potentialities of high pressure for the promotion of studies on the enhancement of protein crystallization processes and correlation between functions and 3D structures of protein molecules. As a tool for enhancing the crystal growth, three of eight proteins show the decrease in its solubility under high pressure. Acceleration of growth and nucleation kinetics of glucose isomerase crystals occurred under high pressure. Step velocities under high pressure provided us direct information on activation volumes during incorporation processes of protein molecules at a kink site of crystals. Such activation volumes were negative in the case of glucose isomerase crystals. Precise discussion on the activation volume will be useful for understanding dehydration mechanisms during the incorporation processes. Usefulness of our standalone-type Be vessel for high-pressure protein crystallography was confirmed. With the vessel, precise high-pressure 3D structure analysis of protein crystals which are also grown under high pressure will be achieved.
• In-Situ Observation of Diffusion, Adsorption and Desorption Processes of Individual Protein Molecules on Protein Crystal Surfaces

  SAZAKI GEN, OKADA MASASHI, DAI GUOLIANG, MATSUI TAKURO, TSUKAMOTO KATSUO, NAKAJIMA KAZUO  日本結晶成長学会誌  40-  (2)  83  -90  2013/07  [Not refereed][Not invited]
   

  We observed in-situ individual fluorescence-labeled protein molecules, to reveal the dynamic behavior of protein molecules during diffusion, adsorption and desorption at an interface between a protein solution and a protein crystal. We found that protein molecules diffused along a crystal surface 4-5 orders of magnitude slower than in a bulk solution, indicating that the molecules strongly interacted with molecules that were aligned at the crystal surface. This result denotes that slow two-dimensional diffusion inside a range of interactions from the crystal surface is a general picture of surface diffusion at an interface between an aqueous solution and a hydrophilic crystal surface. We also found the existence of an induction period (〜70 min) after which the number density of protein molecules adsorbed on steps increased linearly with the adsorption time. We show direct evidences that the residence time of molecules on a crystal surface gradually increases during the transition process from a solute species to the crystal after successive multistep processes.
• 氷ベーサル面上での単位ステップの成長カイネティクス

  ASAKAWA HARUTOSHI, SAZAKI GEN, NAGASHIMA KEN, NAKATSUBO SHUN'ICHI, FURUKAWA YOSHINORI  日本物理学会講演概要集  68-  (1)  992  2013/03/05  [Not refereed][Not invited]
  
• In situ optical observation of the appearance of two types of quasi-liquid layers on ice crystal surfaces

  SAZAKI Gen, ZEPEDA Salvador, NAKATSUBO Shunichi, FURUKAWA Yoshinori  應用物理  82-  (2)  150  -153  2013/02/10
• In-situ observation of elementary steps and quasi-liquid layers on ice crystal surfaces by advanced optical microscopy

  佐﨑 元, ゼペダ サルバドール, 中坪 俊一, 古川 義純  低温科学  71-  1  -13  2013  

  氷は地球上で極めて大量に存在するため, その相転移（成長や融解・昇華）は様々な自然現象を支配する. 特に氷結晶の表面は, 相転移が進行するのみならず, 様々な物理的・化学的過程の鍵を握る. そのため, 氷結晶の表面を分子レベルで理解することは極めて重要であるが, そのような観察手法がこれまではなかった. そこで我々は, 株式会社オリンパスエンジニアリングと共同で開発したレーザー共焦点微分干渉顕微鏡に, その性能を極限まで引き出すべくさらに改良を加えた. そして, 過飽和水蒸気中で成長させた氷結晶（雪結晶と同じ）の表面で, 単位ステップ（結晶表面に偏在する分子層の端）を直接観察することに初めて成功した. これにより, 氷結晶が成長する様子を初めて分子レベルで追跡することが可能となった. また, 同じ手法を用いて, 氷結晶の表面が融点（０℃）以下の温度で融解する過程を初めて可視化することにも成功した. その結果, 形態とダイナミクスが全く異なる２種類の表面液体相（擬似液体層）が出現する事を見出した. 本成果は, 表面液体相が重要な役割を果たす幅広い現象の機構解明に役立つと期待される.Due to the abundance of ice on earth, the phase transition of ice plays crucially important roles in various phenomena in nature. Hence, the molecular-level understanding of ice crystal surfaces holds the key to revealing various phenomena,although so far there has been no means for molecular-level observation. Hence, we tried to improve a laser confocal microscope combined with a differential interference contrast microscope (LCM-DIM), which was developed by us and Olympus Engineering Co., Ltd. Then we succeeded in directly visualizing elementary steps (the growing ends of ubiquitous molecular layers with the minimum height)of ice crystals and their dynamic behavior at air-ice interfaces. We could also directly visualize surface melting processes of ice crystals at temperatures below the melting point (0℃). Then we found that two types of surface-liquid phases (quasi-liquid layers)appear that exhibit different morphologies and dynamics. Such novel insights into the nature of surface-liquid phases may play a crucially important role in understanding a variety of phenomena in which surface-liquid phases play a vital role.
• 氷ベーサル面上での単位ステップの成長カイネティクス

  麻川明俊, 佐崎元, 長嶋剣, 中坪俊一, 古川義純  結晶成長国内会議予稿集(CD-ROM)  43rd-  2013
• ねじれ成長における濃度場のその場観察

  茨城俊介, 荒木優希, 忍健太郎, 緒明佑哉, 佐崎元, 塚本勝男, 今井宏明  結晶成長国内会議予稿集(CD-ROM)  43rd-  ROMBUNNO.08AC08  2013  [Not refereed][Not invited]
  
• 19aFN-6 Strain induces the generation of two types of quasi-liquid layers on ice crystal surfaces

  Sazaki Gen, Asakawa Harutoshi, Nagashima Ken, Nakatsubo Shunichi, Furukawa Yoshinori  Meeting abstracts of the Physical Society of Japan  67-  (2)  824  -824  2012/08/24
• Advanced optical microscopy for observing elementary growth processes of protein crystals

  SAZAKI GEN, OKADA MASASHI, DAI GUOLIANG, VAN DRIESSCHE ALEXANDER, TSUKAMOTO KATSUO, NAKAJIMA KAZUO, FURUKAWA YOSHINORI  日本蛋白質科学会年会プログラム・要旨集  12th-  21  2012/05/31  [Not refereed][Not invited]
  
• In situ Observation of Elementary Steps on Ice Crystal Surfaces by Laser Confocal Microscopy Combined wiht Differential Interference Contrast Microscopy

  SAZAKI Gen, ZEPEDA Salvador, NAKATSUBO Shunichi, FURUKAWA Yoshinori  光学  41-  (1)  33  -35  2012/01/10
• 氷表面上での擬似液体層の生成挙動に対するガスの影響

  麻川明俊, 佐崎元, 長嶋剣, 中坪俊一, 古川義純  日本物理学会講演概要集  67-  (2)  2012
• 氷表面で生成する擬似液体層の安定性

  麻川明俊, 佐崎元, 長嶋剣, 中坪俊一, 古川義純  結晶成長国内会議予稿集(CD-ROM)  42nd-  2012
• 21aRC-7 Colloidal crystallization and irreversible coagulation by uni-directional freezing of water dispersion of polystyrene particles

  Suzuki Yoshihisa, Sazaki Gen, Fujiwara Takahisa, Furukawa Yoshizumi  Meeting abstracts of the Physical Society of Japan  66-  (2)  900  -900  2011/08/24
• 22aJB-2 In-situ observation of effects of antifreeze protein at water-ice interfaces by advanced optical microscopy

  Sazaki Gen, Nakatsubo Shunichi, Furukawa Yoshinori  Meeting abstracts of the Physical Society of Japan  66-  (2)  910  -910  2011/08/24
• 21aRC-8 Effects of pressure on the step velocity of tetragonal hen-egg white lysozyme crystals

  Fujiwara Takahisa, Suzuki Yoshihisa, Sazaki Gen, Yanagiya Shin-ichiro, Tamura Katsuhiro  Meeting abstracts of the Physical Society of Japan  66-  (2)  900  -900  2011/08/24
• 21pRC-2 Direct visualization of elementary growth processes of protein crystals by advanced optical microscopy

  Sazaki Gen, Dai Guoliang, Furukawa Yoshinori  Meeting abstracts of the Physical Society of Japan  66-  (2)  904  -904  2011/08/24
• 酸化物基板表面上の細胞膜モデルシステム : 支持平面脂質膜のダイナミクスと基板表面の影響

  手老 龍吾, 佐崎 元, 宇治原 徹, 宇理須 恒雄  Molecular electronics and bioelectronics  22-  (2)  89  -92  2011/05/30
• Report on the Workshop on "Principle of Nucleation and its Application" in Conjunction with "Elucidation of Ice Crystal Growth by in-situ Observation and Crystal Growth Theory"

  SAZAKI Gen, FURUKAWA Yoshinori  Journal of the Japanese Association of Crystal Growth  38-  (1)  65  -66  2011/04/30
• 25pTH-10 In-situ observation of water-ice (melt-crystal) interfaces by advanced optical microscopy

  Sazaki Gen, Zepeda Salvador, Nakatsubo Shunichi, Furukawa Yoshionri  Meeting abstracts of the Physical Society of Japan  66-  (1)  910  -910  2011/03/03
• 25pTH-11 Effects of pressure on the step velocity of tetragonal hen-egg white lysozyme crystals

  Fujiwara Takahisa, Suzuki Yoshihisa, Sazaki Gen, Yanagiya Shin-ihciro, Tamura Katsuhiro  Meeting abstracts of the Physical Society of Japan  66-  (1)  910  -910  2011/03/03
• 氷の物理化学に関する国際会議(PCI 2010)参加報告

  内田 努, 佐崎 元, 古川 義純, 田崎 友衣子, 谷 篤史, 灘 浩樹, 坂下 真実, 櫻井 俊光, 保井 みなみ, 深澤 裕, 竹谷 敏  雪氷 : 日本雪氷協會雜誌  72-  (6)  391  -396  2010/11/15  [Not refereed][Not invited]
  
• 24aWX-4 Dependence of step velocities on interstep distances : in-situ measurement on monoclinic lysozyme crystal surfaces

  Dai Guoliang, Sazaki G., Sato M., Yokoyama E., Furukawa Y.  Meeting abstracts of the Physical Society of Japan  65-  (2)  844  -844  2010/08/18
• ILTS Workshop on the Latest Developments in Crystal Growth

  SAZAKI Gen, FURUKAWA Yosinori  Journal of the Japanese Association of Crystal Growth  37-  (1)  60  -60  2010/04/30
• 21pGL-5 In-situ observation of surface melting and roughening at air-ice interfaces by advanced optical microscopy

  Sazaki Gen, Zepeda Salvador, Nakatsubo Shunichi, Yokoyama Etsuro, Furukawa Yoshinori  Meeting abstracts of the Physical Society of Japan  65-  (1)  941  -941  2010/03/01
• 27aYH-3 In situ observation of vapor growth of ice crystals by advanced optical microscopy

  Sazaki Gen, Zepeda Salvador, Nakatsubo Shunichi, Yokoyama Etsuro, Furukawa Yoshinori  Meeting abstracts of the Physical Society of Japan  64-  (2)  837  -837  2009/08/18
• 28aYH-1 Explanation of aim : crystal growth of colloids and macromolecules

  Sazaki Gen  Meeting abstracts of the Physical Society of Japan  64-  (2)  295  -295  2009/08/18
• Japan-Netherlands Symposium on Crystal Growth : Theory and in situ Measurements 2008

  FURUKAWA Yoshinori, SAZAKI Gen  Journal of the Japanese Association of Crystal Growth  36-  (1)  55  -56  2009/04/30
• 28pTE-3 In situ observation of crystal surfaces of ice by advanced optical microscopy

  Sazaki Gen, Zepeda Salvador, Nakatsubo Shunichi, Furukawa Yoshinori  Meeting abstracts of the Physical Society of Japan  64-  (1)  891  -891  2009/03/03
• Gravity Dependent Growth Rate of Lysozyme Crystals

  TSUKAMOTO KATSUO, YAMAZAKI TOMOYA, MIURA HITOSHI, PAN WEICHUN, SAZAKI GEN, YOSHIZAKI IZUMI, RUIZ J.GARCIA  結晶成長国内会議予稿集  39th-  58  2009  [Not refereed][Not invited]
  
• Preparation and Characterization of ultraclean H: Si (111)-(1x1) surface studied by HREELS, SFM and STM-STS

  Hiroki Kato, Takumi Taoka, Shozo Suto, Susumu Nishikata, Gen Sazaki, Kazuo Nakajima, Taro Yamada, Ryszard Czajka, Andrzej Wawro, Atsuo Kasuya  e-Journal of Surface Science and Nanotechnology, e-J. Surf. Sci. Nanotech  7-  557  -562  2009  [Not refereed][Not invited]
   

  We review a wet chemical process to prepare the high quality hydrogen-terminated Si(111)-(1×1) surface and show that the two key issues for the high reproducibility are the etching time and the oxygen in the etching solution. We add ammonium sulfite to remove the oxygen according to the previous report [Appl. Surf. Sci. 130, 146 (1998)]. To elucidate the optimal etching time, the vibrational properties and the surface morphology are investigated by high-resolution electron-energy-loss spectroscopy (HREELS), atomic force microscopy (AFM) and scanning tunneling microscopy (STM). The HREELS spectra and images of AFM and STM reveal the precise aqueous NH₄F etching process of Si(111) and indicate the high controllability of steps and terraces with atomic scale. The surface cleanliness and morphology strongly depend on the etching time. At the etching time of 10 min, we obtain an ultra-clean and atomically ordered surface with wide terraces of 36 ± 7 nm step distance. It is confirmed by AFM and STM that the 1.0% ammonium sulfite is useful to remove dissolved oxygen in the 40% NH₄F etching solution and to prepare a high quality H:Si(111)-(1×1) surface with low density of etch pits. The measurement of scanning tunneling spectroscopy(STS) shows the Schottky diode character of the surface. This surface is well applied to the initial stages of the nano-particle and film growth of Ag atoms and Pentacene molecules. [DOI: 10.1380/ejssnt.2009.557]
• Preface for Special Issue on Crystal Growth Controlled by Macromolecules

  FURUKAWA Yoshinori, UENO Satoru, SAZAKI Gen  Journal of the Japanese Association of Crystal Growth  35-  (3)  145  -145  2008/10/31
• Growth rate of protein crystals under microgravity using FOTON-M3 Satellite

  TSUKAMOTO Katsuo, SAZAKI Gen, ONO Erika, KOJIMA Kenichi, TACHIBANA Masaru, KOISHI Mayumi, YOSHIZAKI Izumi, GARCIA RUIZ J. M, VLIEG E  JASMA : Journal of the Japan Society of Microgravity Application  25-  (4)  730  -730  2008/10/30  [Not refereed][Not invited]
  
• 光学顕微技術で見るタンパク質結晶の成長素過程

  佐崎元, VAN DRIESSCHE Alexander E. S, DAI Guoliang, 塚本勝男, 中嶋一雄  応用物理学会学術講演会講演予稿集  69th-  (0)  94  2008/09/02  [Not refereed][Not invited]
  
• 「The 4th Asian Conference on Crystal Growth and Crystal Technology (CGCT-4)」 報告

  太子 敏則, 吉村 政志, 福山 博之, 宇佐美 徳隆, 佐崎 元  日本結晶成長学会誌 = Journal of the Japanese Association for Crystal Growth  35-  (2)  126  -128  2008/07/12
• Visualization of Chiral Molecules on Growing Calcite Surface

  MARUYAMA MIHOKO, TSUKAMOTO KATSUO, SAZAKI GEN, VEKILOV PETER G  結晶成長国内会議予稿集  38th-  99  -100  2008  [Not refereed][Not invited]
  
• Growth processes from solutions revealed by advanced optical microscopy

  SAZAKI GEN, VAN DRIESSCHE A.E.S, DAI G, YOSHIZAKI IZUMI, OTALORA F, TSUKAMOTO KATSUO, NAKAJIMA KAZUO  結晶成長国内会議予稿集  38th-  101  -102  2008  [Not refereed][Not invited]
  
• 21pXL-5 Preparation of High Quality Si (111)1×1 Surface

  Kato H., Taoka T., Nishikata S., Sazaki G., Yamada T., Czajka R., Wawro A., Nakajima K., Kasuya A., Suto S.  Meeting abstracts of the Physical Society of Japan  62-  (2)  917  -917  2007/08/21
• Joint Symposium "Dynamics of Molecular Assembling Processes"

  FURUKAWA Yoshinori, SAZAKI Gen  Journal of the Japanese Association of Crystal Growth  34-  (2)  96  -96  2007/07/12
• 固液界面での結晶成長素過程の高分解光学観察

  佐崎元, 岡田雅史, 松井拓郎, DAI Guoliang, 塚本勝男, 中嶋一雄  電気化学会大会講演要旨集  74th-  128  2007/03/29  [Not refereed][Not invited]
  
• 成長メカニズムに依存するタンパク質結晶の完全性研究ワーキンググループ報告—Report from the WG of dependence of growth condition on the perfection of protein crystals

  塚本, 勝男, 松浦, 良樹, 橘, 勝, 入澤, 寿美, 森, 勇介, 奥津, 哲夫, 和泉, 研二, 西村, 良浩, 吉崎, 泉, 佐崎, 元, Tsukamoto, Katsuo, Matsuura, Yoshiki, Tachibana, Masaru, Irisawa, Toshiharu, Mori, Yusuke, Okutsu, Tetsuo, Waizumi, Kenji, Nishimura, Yoshihiro, Yoshizaki, Izumi, Sazaki, Gen  宇宙利用シンポジウム 第23回 平成18年度 = Space Utilization Research: Proceedings of the Twenty-third Space Utilization Symposium  12  -15  2007/03  

  Correlation between the surface topography of lysozyme crystals which were grown in well controlled condition and X-ray topography of the crystals using monochromatic synchrotron beams were for the first time performed. It was found that the difference of growth step propagation will show up different contrast in the topography, which means that some of the inhomogeneity in the crystals are caused by the difference of step propagation. A new method to use a seed crystal for the X-ray topography is also proposed together with a new space experiment using Photon M3 for the mission in September 2007. 資料番号: AA0063349004
• ”成長メカニズムに依存するタンパク質結晶の完全性”研究ワーキンググループ報告

  塚本勝男, 松浦良樹, 橘勝, 入澤寿美, 森勇介, 奥津哲夫, 和泉研二, 西村良浩, 吉崎泉, 佐崎元, 小沼一雄, 横山悦郎, 小島謙一  宇宙利用シンポジウム  23rd-  2007
• In situ observation of molecular steps on the surface of protein crystal under high pressure

  Yoshihisa Suzuki, Gen Sazaki, Masamitsu Matsumoto, Makoto Nagasawa, Kazuo Nakajima, Katsuhiro Tamura  Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu  17-  (1)  50  -56  2007  [Not refereed][Not invited]
   

  Velocities of elementary steps and two-dimensional nucleation rates on the {101} face of glucose isomerase (GI) crystals were measured at pressures of 0.1, 25 and 50 MPa. We conducted in situ observation of the steps by using a laser confocal microscope combined with differential interference contrast microscope (LCM-DIM) and high-pressure vessel with a sapphire window (t = 1 mm). Both step velocities and 2D nucleation rates increased with increasing pressure at T = 26.4°C and C = 5.6 mg ml-1. Solubilities Ce at high pressures were also measured by in situ observation of the moving steps around equilibrium temperatures. The solubility decreased with increasing pressure.
• The influence of dimer on the nucleation of lysozyme crystal

  KOIZUMI MASAKO, ONO ERIKA, SAZAKI GEN, TSUKAMOTO KATSUO  結晶成長国内会議予稿集  37th-  111  2007  [Not refereed][Not invited]
  
• Photochemically Induced Nucleation in Supersaturated and Undersaturated Thaumatin Solutions

  T. Okutsu, K. Sugiyama, K. Furuta, I. Watanabe, H. Mori, K. Obi, K. Horota, H. Horiuchi, G. Sazaki, S. Veesler, H. Hiratsuka  Photochem. Photobiol. A: Chemistry  2007  [Not refereed][Not invited]
  
• Effects of high pressure on the step velocity and two-dimensional nucleation rate of glucose isomerase crystals

  SUZUKI Yoshihisa, SAZAKI Gen, MATSUMOTO Masamitsu, NAGASAWA Makoto, NAKAJIMA Kazuo, TAMURA Katsuhiro  Journal of the Japanese Association of Crystal Growth  33-  (4)  350  -350  2006/11/30  

  Average step velocities (V_) and two-dimensional nucleation rates on the {101} face of glucose isomerase (GI) crystals increased with increasing pressure at C=5.6 mgml^<-1> (C: GI concentration). Solubility curves of the GI crystals were determined by in situ observation of elementary growth steps under 0.1, 25 and 50 MPa. Kinetic coefficients of V_ had a tendency to increase with increasing pressure.
• Low energy electron microscopic observation of pentacene thin film crystals on a H-Si(111) surface II : a formation mechanism of domain structures

  NISHIKATA S., SAZAKI G., SADOWSKI J. T., AL-MAHBOOB A., FUJIKAWA Y., SUTO S., SAKURAI T., NAKAJIMA K.  Journal of the Japanese Association of Crystal Growth  33-  (4)  236  -236  2006/11/30  

  Dendritic growth of pentacene (Pn) thin film crystals on a H-Si(111) surface was observed in situ by low-energy electron microscopy. We found that each dendrite branch is always composed of three domains with different orientations of 2D unit cells (Fig. 1(a)), and the center domain whose b axes of the 2D unit cell is parallel to the growth direction of the dendrite branch grows faster than outer two domains. This result indicates the direction of the b axis of the Pn 2D unit cell is a preferential growth direction. In addition, since the b axes of the outer two domains are rotated ±60 deg in relation to that of the center domain (Fig. 1(a)), the outer directions of the branch are the preferential growth directions of the outer domains. Hence, when a child branch appears, the outer domain of the mother branch becomes a center domain of the child branch.
• Control of growth directions of pentacene thin film crystals using vicinal steps

  NISHIKATA S., SAZAKI G., TAKEUCHI T., USAMI N., SUTO S., NAKAJIMA K.  Journal of the Japanese Association of Crystal Growth  33-  (4)  237  -237  2006/11/30  

  The "vicinal steps" on a substrate surface are useful to control in-plane orientations of organic thin-film crystals at a "nucleation" stage. In addition to a "nucleation" process, we also focused attention on a "growth" process, on which vicinal steps should also give their effects. Hence, we grew Pentacene (Pn) thin film crystals on vicinal hydrogen-terminated Si(111) (H-Si(111)) surfaces, and studied the effects of vicinal steps of H-Si(111) on the growth of the Pn thin film crystals by observing the morphology of the thin film with atomic force microscopy. We found that the first layer of the Pn thin film crystals exhibited a significantly anisotropic shape on a vicinal H-Si(111) surface: dendritic branches evolved in a lower terrace side (Si[112] direction) but compact shape appeared in an upper terrace side (Si[112] direction), although the first layer showed an isotropic shape on a flat H-Si(111) surface. Furthermore, the growth of the first layer was much faster in the lower-terrace-side direction than in the upper-terrace-side direction. Since such anisotropic growth was observed irrespective of the directions of an incident Pn molecular beam, we tentatively concluded that the cause of the anisotropic growth would be the anisotropy in the incorporation kinetics of Pn molecules at the edges of the thin film crystals on a vicinal surface.
• Low energy electron microscopic observation of pentacene thin film crystals on a H-Si(111) surface I : epitaxial structures

  NISHIKATA S., SAZAKI G., SADOWSKI J. T., AL-MAHBOOB A., FUJIKAWA Y., SUTO S., SAKURAI T., NAKAJIMA K.  Journal of the Japanese Association of Crystal Growth  33-  (4)  235  -235  2006/11/30  

  The growth of pentacene (Pn) thin film crystals on a H-Si(111) surface was observed in situ by low-energy electron microscopy. We succeeded in visualizing not only the morphology of the thin film crystals but also their polycrystalline multi-domain structures. We determined the epitaxial structures of Pn/H-Si(111). We found that there were two types of epitaxial relations. The two kinds of epitaxial relations have almost same molecular packing, but their angular relations with a H-Si(111) surface are different.
• GROWTH MECHANISMS AND DEFECT GENERATION IN PROTEIN CRYSTAL GROWTH

  DOLD P., TSUKAMOTO K., NAKADA T., SAZAKI G.  Journal of the Japanese Association of Crystal Growth  33-  (4)  332  -332  2006/11/30
• Mechanism of Light-induced Nucleation of Protein

  FURUTA Kenji, OKUTSU Tetsuo, YOSHIZAKI Izumi, SAZAKI Gen, HIRATSUKA Hiroshi  Journal of the Japanese Association of Crystal Growth  33-  (4)  345  -345  2006/11/30  

  We investigate the mechanism of light-induced nucleation of protein. The light-induced nucleation of protein was caused through intermediate protein radical. When the radical was scavenged, nucleation was inhibited. Protein dimmers of lysozyme or ribonucleaseA were deteced by electrophoresis experiments, which indicates that the dimer behaves first cluster formation to from protein nucleus.
• Growth mechanisms of protein crystals at high supersaturation

  DOLD PETER, TSUKAMOTO KATSUO, ONO ERIKA, SAZAKI GEN  日本マイクログラビティ応用学会誌  23-  (4)  307  2006/11/30  [Not refereed][Not invited]
  
• Light scattering measurement of calcite nucleation in micro gravity

  MARUYAMA Mihoko, DOLD Peter, SAZAKI Gen, TSUKAMOTO Katsuo  JASMA : Journal of the Japan Society of Microgravity Application = 日本マイクログラビティ応用学会誌  23-  (4)  291  -291  2006/11/30  [Not refereed][Not invited]
  
• Liquid-liquid Phase Separation of Lysozyme Solution under Microgravity

  KOIZUMI Masako, DOLD Peter, SAZAKI Gen, TSUKAMOTO Katsuo  JASMA : Journal of the Japan Society of Microgravity Application = 日本マイクログラビティ応用学会誌  23-  (4)  297  -297  2006/11/30  [Not refereed][Not invited]
  
• In-situ Characterization of Defects during Protein Crystal Growth

  ONO Erika, DOLD Peter, NAKADA Toshitaka, TSUKAMOTO Katsuo, SAZAKI Gen  JASMA : Journal of the Japan Society of Microgravity Application = 日本マイクログラビティ応用学会誌  23-  (4)  298  -298  2006/11/30  [Not refereed][Not invited]
  
• 01aD08 The first direct observation of "the adsorption/desorption process" of individual molecules of fluorescent-labeled protein on a protein crystal surface by a single-molecule visualization technique(NCCG-36)

  Dai Guoliang, Sazaki Gen, Matsui Takuro, Tsukamoto Katsuo, Nakajima Kazuo  Journal of the Japanese Association of Crystal Growth  33-  (4)  239  -239  2006/11/01  [Not refereed][Not invited]
   

  We have succeeded in observing in situ the adsorption process of individual molecules of fluorescent-labeled protein on a protein crystal surface, for the first time. We found that the molecules preferentially adsorb on steps (not on a terrace), and the amount of adsorption suddenly increases after a certain time period (induction time). Existence of the "induction time" indicates that the adsorption proceeds gradually through series of successive elementary processes.
• 01aD09 Roles of impurity adsorption sites on step advancement of a protein crystal(NCCG-36)

  Driessche A. Van, Sazaki G, Yoshizaki I, Otalora F, Tsukamoto K, Nakajima K  Journal of the Japanese Association of Crystal Growth  33-  (4)  240  -240  2006/11/01  [Not refereed][Not invited]
   

  We studied the impurity effects of two impure proteins, fluorescent-labeled lysozyme and covalently-bonded dimmer of lysozyme, on the behavior of elementary growth steps of tetragonal lysozyme crystals. Two impure proteins gave the different supersaturation dependencies of the step velocities. To clarify the cause, we observed in situ the adsorption processes of these two impure proteins on the surface of the lysozyme crystals, and concluded that the different adsorption sites of the impurities resulted in the different supersaturation dependencies of the step velocities.
• 02aD05 Direct measurement of 2D nucleation rate of a protein crystal and impurity effects(NCCG-36)

  Driessche A. Van, Sazaki G, Otalora F, Tsukamoto K, Nakajima K  Journal of the Japanese Association of Crystal Growth  33-  (4)  300  -300  2006/11/01  [Not refereed][Not invited]
   

  By laser con focal microscopy combined with differential interference contrast microscopy, we directly measured the two-dimensional (2D) nucleation rates on {110} faces of tetragonal lysozyme crystals, under various supersaturation, with various impurities added intentionally. We found that all impurities used in our experiments significantly promote heterogeneous 2D nucleation under a low supersaturation range, whereas under a high supersaturation range, homogeneous 2D nucleation dominates the growth of the crystals.
• 03aC02 The influence of liquid : liquid phase separation of protein solution on crystal growth(NCCG-36)

  Koizumi Masako, Dold Peter, Ono Erika, Tsukamoto Katsuo, Sazaki Gen  Journal of the Japanese Association of Crystal Growth  33-  (4)  325  -325  2006/11/01  [Not refereed][Not invited]
   

  The crystallization process of lysozyme crystals via liquid-liquid phase separation was observed in-situ by employing transmission phase-contrast microscopy and growth rate was measured. It is interesting to note that growth rate of crystals becomes considerably large when the liquid-liquid phase separation occurs in the present experiment.
• 03aC03 In-situ Characterization of Defects during Protein Crystal Growth(NCCG-36)

  Ono Erika, Dold Peter, Koizumi Masako, Tsukamoto Katsuo, Sazaki Gen  Journal of the Japanese Association of Crystal Growth  33-  (4)  326  -326  2006/11/01  [Not refereed][Not invited]
   

  Slight in-situ etching method has been applied to the (110) face of tetragonal hen egg-white lysozyme crystals after crystal growth at various conditions, so as to reveal various growth defects in crystal.
• 03aC04 The promoted step velocity of calcite by chiral amino acids(NCCG-36)

  Maruyama Mihoko, Nishimura Yoshihiro, Sazaki Gen, Tsukamoto Katsuo  Journal of the Japanese Association of Crystal Growth  33-  (4)  327  -327  2006/11/01  [Not refereed][Not invited]
   

  Newly developed Phase-Shift Interferometer was introduced for the observation of calcite growth. Calcite was grown in pure and L-aspartic acid (L-Asp) system respectively. Surprising enough, the step velocity with L-Asp was calculated to be 680% larger than that of pure system when σ was 0.2. We therefore concluded that Asp act as a promoter rather than an inhibiter.
• 高分解光学系を用いたタンパク質結晶成長素過程のその場観察--格子欠陥発生機構の解明に向けて (クリスタル小特集)

  佐崎 元, 中嶋 一雄, 塚本 勝男  日本電子材料技術協会会報  37-  17  -20  2006/10  [Not refereed][Not invited]
  
• 25pYC-1 Molecular level in situ observation of elementary growth processes of protein crystals : Approach using macromolecules

  Sazaki Gen, Okada Masashi, Dai Guoliang, Matsui Takuro, Tsukamoto Katsuo, Nakajima Kazuo  Meeting abstracts of the Physical Society of Japan  61-  (2)  746  -746  2006/08/18  [Not refereed][Not invited]
  
• 食品加工における高圧利用の新展開(7)圧力印加による酵素の結晶成長の促進

  鈴木 良尚, 佐崎 元, 松本 雅光  食品と容器  47-  (6)  320  -327  2006
• DEFECT GENERATION DURING CRYSTAL GROWTH OF LYSOZYME

  DOLD Peter, PETROVA Elena, TSUKAMOTO Katsuo, SAZAKI Gen  JASMA : Journal of the Japan Society of Microgravity Application = 日本マイクログラビティ応用学会誌  22-  (4)  289  -289  2005/11/28  [Not refereed][Not invited]
  
• In Situ Observation of Elementary Growth Steps of Glucose Isomerase Crystals under High Pressure

  SUZUKI Yoshihisa, SAZAKI Gen, MATSUMOTO Masamitsu, NAGASAWA Makoto, NAKAJIMA Kazuo, TAMURA Katsuhiro  Journal of the Japanese Association of Crystal Growth  32-  (3)  228  -228  2005/08/17  

  We have observed elementary growth steps of glucose isomerase (GI) crystals by using a laser confocal-diferencial interference contrast microscope at 45MPa, for the first time. Growth mode of the GI crystals at 45MPa was a two-dimensional (2D) nucleation growth mode of a poly-nucleation type. Both step growth rates and 2D nucleation rates increased with increasing pressure.
• In situ measurements of the step velocity of 2D islands on {110} surfaces of tetragonal lysozyme crystals by laser confocal microscopy

  VAN DRIESSCHE A., SAZAKI G., OTALORA F., YOKOYAMA E., TSUKAMOTO K., NAKAJIMA K.  Journal of the Japanese Association of Crystal Growth  32-  (3)  225  -225  2005/08/17  

  We measured the step velocities of 2D islands on {110} faces of tetragonal lysozyrne crystals at different temperatures and supersaturations. We compared them to those obtained by atomic force microscopy (AFM) and interferometry, and attempted to discus the differences.
• THE EFFECT OF SUPERSATURATION ON THE STEP BUNCHING ON LYSOZYME (110)-FACES

  DOLD P., ONO E., TSUKAMOTO K., SAZAKI G.  Journal of the Japanese Association of Crystal Growth  32-  (3)  166  -166  2005/08/17
• In situ measurements of individual protein molecules diffusing in the vicinity of a protein crystal surface

  OKADA Masashi, SAZAKI Gen, MATSUI Takuro, WATANABE Tomonobu, HIGUCHI Hideo, NAKAJIMA Kazuo  Journal of the Japanese Association of Crystal Growth  32-  (3)  277  -277  2005/08/17  

  Diffusing process of individual protein molecules in the vicinity of a protein crystal surface was observed in-situ. By increasing the number of molecules analyzed, we attempted to discuss dynamic behavior of diffusion process.
• The first direct observation of the adsorption process of individual impurity molecules on a protein crystal surface by optical microscopy

  DAI GUOLIANG, SAZAKI GEN, MATSUI TAKURO, TSUKAMOTO KATSUO, NAKAJIMA KAZUO  日本結晶成長学会誌  32-  (3)  278  2005/08/17  [Not refereed][Not invited]
  
• 18aC03 Effects of forced flow on growth of protein crystals(NCCG-35)

  Sazaki Gen, Tsukamoto Katsuo, Yokoyama Etsuro, Nakajima Kazuo  Journal of the Japanese Association of Crystal Growth  32-  (3)  227  -227  2005/08/17  [Not refereed][Not invited]
   

  We applied forced flow to {110} surfaces of tetragonal lysozyme crystals, and observed the growth of spiral growth hillocks in situ using a laser confocal microscope combined with a differential interference contrast microscope. We found that forced flow drastically enhance the transport of impurity to the crystal surface and developed bunched steps all over the crystal surface.
• 18aC02 In situ observation of dislocations inside protein crystals during growth(NCCG-35)

  Sazaki Gen, Yai Satomi, Tsukamoto Katsuo, Nakajima Kazuo  Journal of the Japanese Association of Crystal Growth  32-  (3)  226  -226  2005/08/17  [Not refereed][Not invited]
   

  We successfully observed dislocations and relatively large inclusions inside lysozyme crystals during growth using advanced optical microscopy for the first time. Dislocations were generated in bundles, probably at the periphery of the relatively large inclusions. We also observed the dissolution process of the crystal. Critical undersaturation for point-bottomed etch pits (dislocations) was definitely smaller than that for flat-bottomed ones (micro-defects).
• 17pC05 A method for analyzing motion of steps on a crystal surface using spatio-temporal image(NCCG-35)

  Yokoyama E, Sazaki G, Irisawa T, Furukawa Y, Tsukamoto K  Journal of the Japanese Association of Crystal Growth  32-  (3)  168  -168  2005/08/17  [Not refereed][Not invited]
   

  We propose a method for analyzing motion of steps on the surface for a growing crystal using the cross section of a spatio-temporal volume from an observation image sequence. A step motion is represented as a trajectory in the cross section.
• 17pC04 In Situ Observation of The Crystal Surface of Lysozyme under Microgravity(NCCG-35)

  Tsukamoto Katsuo, Li Chaorong, Sazaki Gen, Yokoyama Etsuro  Journal of the Japanese Association of Crystal Growth  32-  (3)  167  -167  2005/08/17  [Not refereed][Not invited]
  
• Surface observation of protein crystals by high-resolution optical microscopy

  SAZAKI Gen, MATSUI Takuro, TSUKAMOTO Katsuo, NAKAJIMA Kazuo  應用物理  74-  (5)  608  -612  2005/05/10  [Not refereed][Not invited]
  
• Molecular level in situ observation of elementary growth processes of protein crystals by advanced optical microscopy

  G. Sazaki, M. Okada, G. Dai, T. Matsui, K. Tsukamoto, T. Watanabe, H. Higuchi, K. Nakajima  The 3rd Asian Conference on Crystal Growth and Crystal Technology Abstracts, FA03(CD-ROM)  2005  [Not refereed][Not invited]
  
• The first in situ observation of the adsorption process of individual protein molecules on a protein crystal surface under an equilibrium condition

  Dai, G, Sazaki, G, Matsui, T, Tsukamoto, K, Nakajima, K  The 3rd Asian Conference on Crystal Growth and Crystal Technology Abstracts, FA09 (CD-ROM)  2005  [Not refereed][Not invited]
  
• High-Quality Protein Crystals Grown in High-Viscous Crystallization Solution under Microgravity Environment

  YAMANAKA Mari, TANAKA Hiroaki, TAKAHASHI Sachiko, INAKA Koji, SUGIYAMA Shigeru, SATO Masaru, MOTOHARA Moritoshi, SANO Satoshi, YOSHIZAKI Izumi, NAKAMURA Hirohiko, FUKUYAMA Seijiro, KOBAYASHI Tomoyuki, YOSHITOMI Susumu, SAZAKI Gen, KOMATSU Hiroshi  JASMA : Journal of the Japan Society of Microgravity Application = 日本マイクログラビティ応用学会誌  21-  2  -2  2004/11/04
• Effect of Growth Mechanism on The Formation of Defects in Protein Crystals

  TSUKAMOTO Katsuo, SAZAKI Gen  JASMA : Journal of the Japan Society of Microgravity Application = 日本マイクログラビティ応用学会誌  21-  5  -5  2004/11/04  [Not refereed][Not invited]
  
• Effects of Internal Electric Field (Direct Current) on Protein Crystallization

  SAZAKI Gen, MORENO Abel, NAKAJIMA Kazuo  Journal of the Japanese Association of Crystal Growth  31-  (3)  201  -201  2004/08/25  

  We have studied the effects of an internal electric field (direct current) on protein crystallization. In the case of the internal electric field, similar effects to those found in an external field (no current) could be obtained by applying very small voltage and current (1.9mV, 2.0μA). In addition, we found novel coupling effects when the internal electric field and a magnetic field were applied at the same time.
• Impurity effects of fluorescent labeled lysozyme on the crystallization of tetragonal and monoclinic crystals

  MATSUI T, SAZAKI G, OKADA M, MATSUURA Y, FUJIWARA K, UJIHARA T, USAMI N, NAKAJIMA K  Journal of the Japanese Association of Crystal Growth  31-  (3)  194  -194  2004/08/25  

  To grow high quality protein crystals, impurity effects have to be studied from the viewpoint of intermolecular bondings. Recently, intermolecular bondings in hen egg-white lysozyme (HEWL) crystals were systematically studied by Matuura and Chemov. Based on their results, we modified the specific surface of HEWL with fluorescent reagent, and studied the impurity effects on the nucleation and growth of tetragonal and monoclinic HEWL crystals.
• A molecular-level discussion on the growth kinetics of glucose isomerase crystals

  SUZUKI Yoshihisa, SAZAKI Gen, MATSUURA Yoshiki, HONDOH Hironori, SAKURABA Haruhiko, OHSHIMA Toshihisa, NAKAJIMA Kazuo, TAMURA Katsuhiro  Journal of the Japanese Association of Crystal Growth  31-  (3)  203  -203  2004/08/25  

  Growth rates of (101) face of glucose isomerase crystals kinetically increased with increasing pressure. We have concluded that the increase in the growth rate was due to a decrease in the average step ledge energy of two-dimensional islands on the (101) face.
• In situ observation of the diffusing process of individual protein molecules in the vicinity of crystal surfaces

  OKADA Masashi, SAZAKI Gen, MATSUI Takuro, WATANABE Tomonobu, HIGUCHI Hideo, NAKAJIMA KAZUO  Journal of the Japanese Association of Crystal Growth  31-  (3)  250  -250  2004/08/25  

  In this study, we have applied a single molecule visualization technique and succeeded in directly observing the anisotropic diffusion process of individual protein molecules in the vicinity of crystal surfaces, for the first time.
• 26aA03 In situ Observation of Elementary Growth Steps of Protein Crystals by Laser Confocal Differential Interference Contrast Microscopy(NCCG-34)

  Sazaki Gen, Matsui Takuro, Okada Masashi, Tsukamoto Katsuo, Nakajima Kazuo  Journal of the Japanese Association of Crystal Growth  31-  (3)  193  -193  2004/08/25  [Not refereed][Not invited]
   

  In this study, we have developed laser confocal microscopy combined with differential interference contrast microscopy, and succeeded in observing elementary growth steps of 5.6nm in height and two-dimensional nucleation growth on the {110} faces of tetragonal lyusozyme crystals in situ.
• 25pA3 In situ Observations of Elementary Growth Steps on Protein Crystals and Individual Protein Molecules Diffusing in the Vicinity of Crystal Surfaces(NCCG-34)

  Sazaki Gen, Okada Masashi, Matsui Takuro, Higuchi Hideo, Watanabe Tomonobu, Tsukamoto Katsuo, Nakajima Kazuo  Journal of the Japanese Association of Crystal Growth  31-  (3)  115  -116  2004/08/25  [Not refereed][Not invited]
   

  Mechanisms of defects incorporation have to be clarified to grow high quality single crystals. To approach this problem, elementary growth processes, such as 1) movement of elementary growth steps and 2) diffusion of solute molecules in the vicinity of crystal surfaces have to be observed in situ. Recently, we have succeeded in observing these elementary processes by advanced optical microscopy utilizing large size of protein molecules.
• 28aYE-5 In situ observation of elementary growth processes of protein crystals at a molecular level

  Sazaki G, Okada M, Matsui T, Higuchi H, Tsukamoto K, Nakajima K  Meeting abstracts of the Physical Society of Japan  59-  (1)  364  -364  2004/03/03  [Not refereed][Not invited]
  
• SiGeバルク単結晶と多結晶の成長技術およびそれらのデバイス応用； 均一組成のバルク単結晶とミクロ分散的組成分布を有する太陽電池用バルク多結晶

  中嶋一雄, 藤原航三, 宇佐美徳隆, 藩 伍根, 佐崎 元, 宇治原徹, 宍戸統悦  日本結晶成長学会誌  31-  (1)  29  -37  2004/01  [Not refereed][Not invited]
  
• Effects of High Pressure on Protein Crystallization

  SAZAKI Gen, NAKAJIMA Kazuo, SUZUKI Yoshihisa, TAMURA Katsuhiro, MIYASHITA Satoru, SAWADA Tsutomu, KOMATSU Hiroshi  X-RAYS  46-  (2)  152  -158  2004  [Not refereed][Not invited]
   

  Hydrostatic pressure is a useful parameter to control protein crystallization. One can change the solubility of protein crystals quickly by changing pressure. Information about the hydration of the specific surfaces of protein molecules can be obtained from the pressure dependency of solubility. When a protein molecule is hydrophobic or when its molecular volume in a solution is significantly larger than that in a crystal, applying high pressure is expected to be an effective method to promote crystallization. Pressure also affects the growth kinetics of protein crystals. Dependency of a growth rate on a driving force for crystallization was measured on typical proteins and analyzed using a two-dimensional nucleation growth model of a poly-nuclei type. High-pressure effects on growth kinetics could be explained by changes in a surface free energy, an activation energy and an average distance between kinks. Common understanding, however, has not yet been obtained for growth kinetics.
• The Origin of the Structural Phase Transition in the Growth of Ultra-Thin Bi Films on Si(111)

  J. T. Sadowski, T. Nagao, M. Saito, S. Yaginuma, Y. Fujikawa, G. E. Thayer, R. M. Tromp, K. Nakajima, G. Sazaki, T. Ohno, T. Sakurai  AIP Conf. Proc.  696-  738  -744  2003/12  [Not refereed][Not invited]
  
• Hetero-epitaxial structure of organic semiconductor PTCDA thin film crystals on hydrogen-terminated Si (111) surfaces

  SAZAKI Gen, FUJINO Takuho, SADOWSKI Jerzy T., USAMI Noritaka, UJIHARA Toru, FUJIWARA Kozo, SAKURAI Toshio, NAKAJIMA Kazuo  Journal of the Japanese Association of Crystal Growth  30-  (3)  111  -111  2003/07/05  

  Thin film crystals of organic semiconductor PTCDA were grown on hydrogen-terminated Si(111) surfaces by MBE method. Hetero-epitaxial structure of the thin film crystals was determined using UHV-STM. We found that its lattice matching mode is close to commensurate one.
• Control of the grain orientation of organic semiconductor PTCDA thin film crystals using vicinal steps on hydrogen-terminated Si (111) surface

  SAZAKI Gen, FUJINO Takuho, GUNJI Atsushi, NISHIKATA Susummu, USAMI Noritaka, UJIHARA Toru, FUJIWARA Kozo, NAKAJIMA Kazuo  Journal of the Japanese Association of Crystal Growth  30-  (3)  112  -112  2003/07/05  

  Orientation of the grains of organic semiconductor PTCDA thin film crystals was controlled using vicinal steps on hydrogen-terminated Si(111) substrates. The ratio of single crystalline grains on the vicinal substrate was 10% larger than that on fiat substrate. This increase in the ratio of single crystalline grains is probably due to the preferential orientation of the PTCDA molecules along the steps.
• Real-time measurement of protein concentration for supersaturation control

  MATSUI Takuro, SAZAKI Gen, USAMI Noritaka, UJIHARA Toru, FUJIWARA Kozo, NAKAJIMA Kazuo  Journal of the Japanese Association of Crystal Growth  30-  (3)  80  -80  2003/07/05  

  In protein crystallization, supersaturation control is one of the most basic approaches to grow a high quality single crystal. In order to apply this approach, protein concentration should be monitored all though the crystallization process. Then we tried to develop a real-time monitoring system of protein concentration using a two-beam interferometer. This system enable us to measure the protein concentration with following advantages: wide dynamic range, small volume, and applicable in micro batch and dialysis systems.
• Poly-crystallization due to strain-induced constitutional supercooling

  UJIHARA Toru, AZUMA Yukinaga, FUJIWARA Kozo, SAZAKI Gen, USAMI Noritaka, NAKAJIMA Kazuo  Journal of the Japanese Association of Crystal Growth  30-  (3)  55  -55  2003/07/05  

  When a crystal is strained during growth from a solution, the solution in the vicinity of interface is supersaturated. Based on the fact, we proposed the model of poly-crystallization due to strain during solution growth. According to our model, strain free crystals nucleate heterogenerously on the strained crystal and consequently poly-crystallization occurs. The results of Monte Carlo simulations support the model of the poly-crystallization due to strain.
• Crystal Surface and Defects in Protein Crystals Revealed by High-Resolution Optical Microscopies

  Tsukamoto Katsuo, Yai Satomi, Sazaki Gen  Journal of the Japanese Association of Crystal Growth  30-  (3)  81  -81  2003/07/05  [Not refereed][Not invited]
   

  High resolution microscopies have successfully been applied to reveal monomolecular growth steps of protein crystals during crystal growth, the method of which has also been applied to reveal defects in the protein crystals by slight etching to find the mutual relation between growth centers and defects. Dislocations with hollow cores were found to be responsible for the formation of giant spiral hillocks. While, a large numbers of microdefects revealed as shallow etch pits were found to promote 2D nucleation growth on the lysozyme crystals because of the linear relationship between the density of the shallow etch pits and the 2D islands.
• 有機半導体薄膜結晶化の現状 : どこまでわかっているか

  佐崎 元, 中嶋 一雄  應用物理  72-  (6)  774  -775  2003/06/10
• Preface of Special Issue on Biocrystallization

  SAZAKI Gen  Journal of the Japanese Association of Crystal Growth  30-  (1)  2  -2  2003/03/25
• Crystallization control of glucose isomerase under high pressure

  Suzuki Yoshihisa, Sazaki Gen, Visuri Kalevi, Tamura Katsuhiro, Nakajima Kazuo  Meeting abstracts of the Physical Society of Japan  58-  (1)  842  -842  2003/03/06
• 基礎セミナー タンパク質の結晶化:結晶成長学から提言

  佐崎 元, 中嶋 一雄  構造生物  8-  (3)  34  -48  2003
• Protein crystallization under high hydrostatic pressure

  Yoshihisa Suzuki, Gen Sazaki, Tsutomu Sawada, Satoru Miyashita, Hiroshi Komatsu, Katsuhiro Tamura  Review of High Pressure Science and Technology/Koatsuryoku No Kagaku To Gijutsu  13-  (2)  149  -156  2003  [Not refereed][Not invited]
   

  In this article, recent advances in the fundamental research in the protein crystallization under high pressure were reviewed. Pressure is expected to be an important parameter to control protein crystallization, since hydrostatic pressure affects the whole system uniformly and can be changed very rapidly. So far, a lot of studies of protein crystallization under high pressure have been done, some less systematic than others. We have particularly focused on fundamental aspects (the solubility and the crystal growth kinetics) of protein crystallization under high pressure. The studies reviewed contribute significantly to high-pressure crystallography and high-pressure protein science.
• Impact of the annealing temperature on the homogeneity of SiGe-on-insulator

  N. Usami, K. Kutsukake, K. Fujiwara, T. Ujihara, G. Sazaki, S. Ito, B. P. Zhang, K. Nakajima  Third International Conference of SiGe(C) Epitaxy and Heterostructures  200  -202  2003  [Not refereed][Not invited]
  
• Impurity effect on the quality of protein crystals

  MATSUI Takuro, SAZAKI Gen, SATO Takao, UJIHARA Toru, FUJIWARA Kozo, USAMI Noritaka, NAKAJIMA Kazuo  Journal of the Japanese Association of Crystal Growth  29-  (2)  71  -71  2002/07/01  

  Impurity effect was investigated on the crystallization of the hen egg lysozyme tetragonal crystals. From the X-rey diffraction data and the observation of the growth sector boundary, we found that quality of the crystals decreases with a decrease in the supersaturation.
• Can strain induce poly-crystallization during melt growth?

  UJIHARA Torn, FUJIWARA Kozo., SAZAKI Gen., USAMI Noritaka, NAKAJIMA Kazuo  Journal of the Japanese Association of Crystal Growth  29-  (2)  146  -146  2002/07/01  

  Strain in crystals lowers the melting point. On a basis of this fact, we newly explained the strain induced poly-crystallization during met growth. According to our model, strain free crystal nucleates heterogenerously on the strained crystal from the supercooled melt in the vicinity of liquid-solid interface. Moreover, we successfully reproduced the poly-crystallization due to this model by the Monte Carlo simulation.
• Effects of a Pressure on the Growth Kinetics of Glucose Isomerase Crystals

  SUZUKI Y., SAZAKI G., VISURI Kalevi., TAMURA K., NAKAJIMA K.  Journal of the Japanese Association of Crystal Growth  29-  (2)  74  -74  2002/07/01  

  Solubility and growth rates of the crystals of glucose isomerase under high pressure have been measured. The solubility significantly decreased with increasing pressure. The growth rates of (101) face of the crystals at 100 MPa (30℃) were slightly larger than those at 0.1 MPa at the same supersaturation.
• Impurity effects of hydrothermally grown ZnO single crystals

  MIYASHITA S., TAMAO T., OKABE T., SEKIGUCHI T., SAKAGAMI N., OBARA K., SHISHIDO T., SAZAKI G., NAKAJIMA K.  Journal of the Japanese Association of Crystal Growth  29-  (2)  115  -115  2002/07/01  

  ZnO crystals doped with Al_2O_3, Ga_2O_3, In_2O_3 were hydrothermally grown in order to be used as homo-epitaxial growth substrates. Growth behavior and electrical and optical properties of these are reported.
• 24aWD-9 Faculty of Engineering, The Univ. Tokushima

  Suzuki Yoshihisa, Sazaki Gen, Visuri Kalevi, Tamura Katsuhiro, Nakajima Kazuo  Meeting abstracts of the Physical Society of Japan  57-  (1)  818  -818  2002/03/01
• Effects of a Magnetic Field on the Crystallization of Protein

  G. Sazaki, S. Yanagiya, S. D. Durbin, S. Miyashita, T. Nakada, H. Komatsu, T. Ujihara, K. Nakajima, K. Watanabe, M. Motokawa  Materials Science in Static High Magnetic Fields, edited by K. Watanabe and M. Motokawa,Springer-Verlag, Berlin  283  -300  2002  [Not refereed][Not invited]
  
• Protein Crystallization : Increase in the Crystal Perfection by Applying a Magnetic Field

  SAZAKI Gen, SATO Takao, MATSUURA Yoshiki, NAKAJIMA Kazuo  Bulletin of the Japan Institute of Metals  41-  (7)  481  -488  2002  [Not refereed][Not invited]
  
• 第11回結晶成長国際夏期スクール(ISSCG-11)報告

  佐藤 清隆, 古川 義純, 大鉢 忠, 中嶋 一雄, 宇佐美 徳隆, 佐崎 元  日本結晶成長学会誌  28-  (4)  233  -240  2001/12/15
• In-situ observation of the Marangoni convection in a protein solution under microgravity

  SAZAKI Gen, MIYASHITA Satoru, UJIHARA Toru, FUJIWARA Kozo, USAMI Noritaka, NAKAJIMA Kazuo  JASMA : Journal of the Japan Society of Microgravity Application  18-  79  -79  2001/10/01
• Novel measurement method for diffusion coefficients of high temperature solutions based on Fick's first law

  FUJIWARA Kozo, UJIHARA Toru, SAZAKI Gen, USAMI Noritaka, NAKAJIMA Kazuo  JASMA : Journal of the Japan Society of Microgravity Application  18-  65  -65  2001/10/01
• Morphology and Solubility of a New Crystal Growth Model Protein Taka-amylase A

  NINOMIYA Kumiko, YAMAMOTO Tenyu, OHEDA Tadashi, SATO Kiyotaka, SAZAKI Gen, MATSUURA Yoshiki  JASMA : Journal of the Japan Society of Microgravity Application  18-  74  -74  2001/10/01
• Observation of para-nitroaniline crystals by Laue Topography using Synchrotoron Radiation

  Yanagiya S., Izumi K., Imai Y., Kajiwara K., Hondo H., Matsui T., Sazaki G., Nakajima K., Mori A., Inoue T.  Meeting abstracts of the Physical Society of Japan  56-  (2)  718  -718  2001/09/03
• Evaluation of the quality of protein crystals by X-ray Laue topography

  Sazaki G., Matsui T., Miyashita S., Hondoh H., Yanagiya S., Kajiwara K., Imai Y., Izumi K., Ujihara T., Fujiwara K., Usami N., Nakajima K.  Meeting abstracts of the Physical Society of Japan  56-  (2)  719  -719  2001/09/03
• 汚れが対流を遅くする--微小重力下での水溶液中のマランゴニ対流のその揚観察:タンパク質の結晶化に及ぼす影響について (<特集>第3回21世紀の境界領域研究を考えるシンポジウム)

  佐崎 元, 宮下 哲, 野倉 正樹  バウンダリ-  17-  (8)  17  -19  2001/08
• Preface for Special Issue on Environmental Problem and Crystal Growth

  SAZAKI Gen, SHIMAMURA Kiyoshi  日本結晶成長学会誌  28-  (2)  52  -52  2001/06/26
• Effects of protein concentration and gas adsorption on the Marangoni convection of protein solution

  Sazaki G., Miyashita S., Ujihara T., Fujiwara K., Usami N., Nakajima K.  Meeting abstracts of the Physical Society of Japan  56-  (1)  781  -781  2001/03/09
• 生体高分子の結晶化に及ぼす磁場の影響 (強磁場下の結晶成長及び強磁場の化学・生物学効果の研究)

  佐崎 元, 松井 拓郎, 中嶋 一雄  東北大学金属材料研究所強磁場超伝導材料研究センター年次報告  2001-  186  -189  2001
• In-situ observation of the Marangoni convection in a protein solution under microgravity

  Sazaki Gen, Miyashita Satoru, Ujihara Toru, Usami Noritaka, Nakajima Kazuo  Meeting abstracts of the Physical Society of Japan  55-  (2)  747  -747  2000/09/10
• 強磁場下でのタンパク質の結晶成長 (第2回「21世紀の境界領域研究を考えるシンポジウム」)

  佐崎 元, 柳谷 伸一郎, Durbin Stephen D.  バウンダリ-  16-  (9)  32  -33  2000/09
• Morphology and Solubility of Taka-Amylase A(TAA) crystals

  YAMAMOTO Tenntyu, SATO Kiyotaka, MATSUURA Yoshiki, SAZAKI Gen  Journal of the Japanese Association of Crystal Growth  27-  (1)  115  -115  2000/07/01  

  solubility values and morphological changes of taka-amylase A crystals were examined in solutions using two types of precipitants; ammonium surface and PEG 8000.
• AFM observation of monoclinic HEWL crystal

  HONDOH H., SAZAKI G., MIYASHITA S., DURBIN S.D., NAKAJIMA K, MATSUURA Y.  Journal of the Japanese Association of Crystal Growth  27-  (1)  113  -113  2000/07/01  

  In-situ observation of micro-morphology on the (10-1) face was carried out using Atomic Force Microscope with a tapping mode. A number of spiral steps have been observed on the surface. The features of the surface micro-morphology will be discussed using the anisotropy of macrobonds on the step edges.
• Effects of a Magnetic Field on the Growth Rate of Protein Crystals

  SAZAKI G., YANAGIYA S., DURBIN Stephen D., MIYASHITA S., UJIHARA T., USAMI N., NAKAJIMA K., MOTOKAWA M.  Journal of the Japanese Association of Crystal Growth  27-  (1)  131  -132  2000/07/01  

  Magnetic field effects on the growth rate of protein crystals and the convection in an aqueous electrolyte solution are outlined. It was found that a steady and homogeneous magnetic field decreased the growth rate of hen egg-white lysozyme crystals and also the flow rate of the buoyancy convection in a NaCl aqueous solution. The magnetic damping of the convection may be responsible for the decrease in the growth rate.
• In-situ observation of the Marangoni flow of water under microgravity

  SAZAKI G., MIYASHITA S., UJIHARA T., USAMI N., NAKAJIMA K.  Journal of the Japanese Association of Crystal Growth  27-  (1)  51  -51  2000/07/01  

  Marangoni flow in 7.35 wt% NaCl aqueous solution was observed in-situ using drop experiment facility of MGLAB at Toki. It was found that the contamination of water-air interface strongly affect on the Marangoni flow and the flow rate decreased to smaller than 1/4 within 30 min.
• Enhancements of resolution maximum of diffaction in protein crystal grown under high magnetic field

  Sato Takao, Yamada Yusuke, Saijo Shinya, Tanaka Nobuo, Sazaki Gen, Nakajima Kazuo, Igarashi Noriyuki, Tanaka Masahiko, Matsuura Yoshiki  Journal of the Japanese Association of Crystal Growth  27-  (1)  114  -114  2000/07/01  [Not refereed][Not invited]
   

  Orthorhombic lysozyme crystals grown under high magnetic field showed improvements both in maximum resolution of diffraction ( 1.33Å to 1.13Å) and lower mosaicity (30 % decrease) for X-ray analysis.
• 生体高分子の結晶化に及ぼす磁場の影響 (強磁場下の結晶成長及び強磁場の化学・生物学効果の研究)

  佐崎 元, Durbin Stephen D., 宮下 哲  東北大学金属材料研究所強磁場超伝導材料研究センタ-年次報告  (1999)  196  -204  2000/06
• Molecular contacts and crystal growth of lysozyme monoclinic crystal

  Hondoh H., Sazaki G., Miyashita S., Durbin S. D., Nakajima K., Matsuura Y.  Meeting abstracts of the Physical Society of Japan  55-  (1)  767  -767  2000/03/10
• 生体高分子の結晶化に及ぼす磁場の影響

  佐崎 元, Durbin Stephen D., 宮下 哲  東北大学金属材料研究所強磁場超伝導材料研究センター年次報告  2000-  222  -232  2000
• Effects of a Magnetic Field on Protein Crystallization

  SAZAKI Gen, YANAGIYA Shin-inchiro, DURBIN Tephen D, MIYASHITA Satoru, NAKADA Toshitaka, KOMATSU Hiroshi, NAKAJIMA Kazuo, MOTOKAWA Mitsuhiro  Journal of the Surface Science Society of Japan  20-  (11)  770  -776  1999/11/10
• Pressure Effects of Crystallization of Hen Egg White Lysozyme

  MIYASHITA S, SAZAKI G, NAGATOSHI Y, SUZUKI Y, SAWADA T, NAKADA T, KOMATSU H, NAKAJIMA K  Journal of the Japanese Association of Crystal Growth  26-  (4)  192  -202  1999/09/30  

  Pressure effects of crystallization of protein were studied with hen egg white lysozyme as a model protein. Direct observation with use of a diamond anvil cell revealed that the solubility of tetragonal form crystals increased and that the nucleation rate decreased with pressure. To conduct quantitative studies on the crystal growth rates, a novel technique was developed for the rapid solubility measurement under high pressures by two-beam interferometry. The solubility of tetragonal form crystals was determined as a function of temperature at 0.1, 50, and 100 Mpa. And that of orthorhbmbic ones was measured at 0.1 and 100 Mpa. It was shown that the solubility of the tetragonal crystals in-creases with pressure, while the solubility of the orthorhombic crystals decreases with increasing pressure. This tendency was discussed by considering the hydration of the molecular binding sites in the crystals. Normal growth rates were also measured as a function of supersaturation under high pressures. They decreased with pressure. It indicates that the surface growth kinetics depends on pres-sure significantly. The birth and spread model was applied to understand the pressure effects on the growth kinetics. It was found that increase in the average ledge surface energy of the two dimensional nuclei with pressure explained decrease in the growth rate.
• 24aZ-11 Impurty effects on the growth rate of leucine complex crystal

  Hasegawa H., Miyashita S., Sasaki G., Nakada T., Komatsu K.  Meeting abstracts of the Physical Society of Japan  54-  (2)  786  -786  1999/09/03
• 25pZ-6 Magnetic damping effects on NaCl aqueous solution

  SASAKI G, MIYASHITA T, Durbin S.D, UJIHARA T, Nakajima K, Motokawa M  Meeting abstracts of the Physical Society of Japan  54-  (2)  810  -810  1999/09/03
• 25pZ-1 Optical properties of hydorothemally grown ZnO single crystals

  Miyashita T, Sekiguchi T, Nishimura Y, Ohara K, Shishido T, Sasaki G, Nakajima K, Haga K  Meeting abstracts of the Physical Society of Japan  54-  (2)  809  -809  1999/09/03  [Not refereed][Not invited]
  
• Growth kinetics of orthorhombic lysozyme crystals under high pressure

  SAZAKI G., NAGATOSHI Y., D. DURBIN Stephen, MIYASHITA S., UJIHARA T., NAKAJIMA K.  Journal of the Japanese Association of Crystal Growth  26-  (2)  107  -107  1999/07/01  

  Growth rate of orthorhombic lysozyme crystals was measured in situ under 0.1 and 100 Mpa. High pressure effect was to decrease the growth kinetics of orthorhombic crystals as in the case of the tetragonal ones.
• Crystal structure of hen egg-white lysozyme within high magnetic-field environment

  SATO Takao, KATSUYA Yoshio, SAZAKI Gen, MATSUURA Yoshiki  Journal of the Japanese Association of Crystal Growth  26-  (2)  105  -105  1999/07/01  

  The effect of a magnetic field on HEW lysozyme crystals was studied using X-ray structure analysis. Both crystals of tetragonal form were grown with and without the high magnetic field. The two structures are nearly identical with the r. m. s. deviation 0.5Å. The changes of the side-chain of amino acid within C-terminus were found out at the interface between adjacent molecules. This difference will be hereafter discussed by use of the structure of orthorhombic crystal.
• Optical property of hydrothermally grown ZnO single crystals

  MIYASHITA S, NISHIMURA Y, SEKIGUCHI T, OBARA K, SAZAKI G, SHISHIDO T, NAKAJIMA K, SAKAGAMI N  Journal of the Japanese Association of Crystal Growth  26-  (2)  40  -40  1999/07/01  [Not refereed][Not invited]
   

  Optical property of hydrothermally grown ZnO single crystals was measured by the cathode luminescence method. The obtained spectra from as-growth surfaces differed depending on the type and amount of the defects. The growth sector of the m-surface had the best optical property.
• 29p-N-5 Crystal growth mechanism of an L-leucine complex in flowing solution

  Hasegawa K., Miyashita S., Sazaki G., Nakada T., Komatsu H.  Meeting abstracts of the Physical Society of Japan  54-  (1)  92  -92  1999/03/15
• 30p-N-12 In-situ Observation of Temperature Distribution Around Growing Crystals from Melt

  Sazaki G., Miyashita S., Nakajima K.  Meeting abstracts of the Physical Society of Japan  54-  (1)  95  -95  1999/03/15
• 31a-N-6 In-situ observation of protein crystal growth under a magnetic field

  Yanagiya Shinichiro, Sazaki Gen, Durbin Stephen D., Miyashita Satoru, Nakajima Kazuo, Watanabe Kazuo, Motokawa Mitsuhiro, Komatsu Hiroshi  Meeting abstracts of the Physical Society of Japan  54-  (1)  97  -97  1999/03/15
• Report on 7th International Conference on the Crystallization of Biological Macromolecules (ICCBM-7)

  Sazaki Gen  Journal of the Japanese Association of Crystal Growth  25-  (4)  175  -177  1998/09/30
• Impurity effccts on the growth of lysozyme crystals

  NAKADA T., SAZAKI G., MIYASHITA S., DURBIN S.D, KOMATSU H.  Meeting abstracts of the Physical Society of Japan  53-  (2)  98  -98  1998/09/05
• Polymorphs and solubilities of lysozyme crystals under high pressure

  NAGATOSHI Yukiko, SAZAKI Gen, SUZUKI Yoshihisa, DURBIN Stephen D, MIYASHITA Satoru, NAKADA Toshitaka, KOMATSU Hiroshi  Meeting abstracts of the Physical Society of Japan  53-  (2)  97  -97  1998/09/05
• Concentration field around a growing crystal in microgravity

  MIYASHITA S., KURIHARA K., HASEHAWA K., SAZAKI G., NAKADA T., D. DURBIN Sephen, KOMATSU H.  Journal of the Japanese Association of Crystal Growth  25-  (3)  A147  1998/07  

  Change in concentration distribuion around a growing crystal caused by a sudden change in gravity from 1g to μg was measured with interferometric optical microscopy. Effect of the buoyancy driven convection on the concentration distribution is discussed with the results.
• Pressure dependence on solubility of orthorhombic lysozyme crystal

  SAZAKI Gen, NAGATOSHI Yukiko, SUZUKI Yoshihisa, D. DURBIN Stephen, MIYASHITA Satoru, NAKADA Toshitaka, KOMATSU Hiroshi  Journal of the Japanese Association of Crystal Growth  25-  (3)  A91  1998/07  

  Pressure dependence of sulubilities of both tetragonal and orthorhombic form crystals of HEW lysozyme was studied using an improved interference microscope. Solubility of orthorhombic form decreased with pressure, while that of tetragonal form increased. This difference is discussed thermodynamically and explained by use of the concept of the contact area between molecules.
• Incorporation of impurity to a tetragonal lysozyme crystal

  KURIHARA Kazuo, MIYASHITA Satoru, SAZAKI Gen, NAKADA Toshitaka, KOMATSU Hiroshi, OHBA Tetsuhiko, OHKI Kazuo  Journal of the Japanese Association of Crystal Growth  25-  (3)  A90  1998/07  

  Concentration of a phosphor-labeled impurity (ovalbumin) incorporated into protein (lysozyme) crystals during growth was measured by fluorescence. Impurity concentration increased with growth rate, which could not be explained by two conventional models. Impurity concentration also increased with the pH of the solution. This result is discussed considering the electrostatic interaction between the impurity and the crystallizing species.
• Growth and characterization of single crystals of Y_2Cu_2O_5 by the TSFZ method

  NISHIMURA Y, MATSUOKA Y, MIYASHITA S, SAZAKI G, NAKADA T, KOMATSU H, MITSUDO S, MOTOKAWA M  Journal of the Japanese Association of Crystal Growth  25-  (3)  A123  1998/07  [Not refereed][Not invited]
   

  Liquidus composition of the Y_2Cu_2O_5 was confirmed by in-situ method under a high temperature optical microscop. With this result. Y_2Cu_2O_5 single crystals were successfully grown by the TSFZ method. This crystal showed antiferromagnetic transition below 13K and metamagnetic behavior which two magnetization steps were observed.
• Measurement of The Solubility of Oboalubmin Crystals

  Yoneda K, Tsukamoto K, Sato H, Matsubara Y, Sazaki G  Journal of the Japanese Association of Crystal Growth  25-  (3)  A156  1998/07/01  [Not refereed][Not invited]
   

  The solubility of oboalubmin was measured by observing the critical concentration of alubumin and ammonium sulfate under the microscope.
• Concentration field around a growing crystal in microgravity.

  MIYASHITA S., KURIHARA K., HASEGAWA K., SAZAKI G., NAKADA T., DURBIN S., KOMATSU H.  Meeting abstracts of the Physical Society of Japan  53-  (1)  90  -90  1998/03/10
• 6a-P-6 Phase Transition of Paraffin Crystals

  Izumi K., Sazaki G., Miyashita T.  Meeting abstracts of the Physical Society of Japan  52-  (2)  88  -88  1997/09/16
• 6p-P-5 Step kinetics of the silver single crystal surface in perchloric acid

  Ujihara T., Nakada T., Miyashita S., Sazaki G., Komatsu H.  Meeting abstracts of the Physical Society of Japan  52-  (2)  91  -91  1997/09/16
• 6a-P-8 The relation between growth rate and impurity incorporation in lysozyme crystals.

  Kurihara Kazuo, Miyashita Satoru, Sazaki Gen, Makada Toshitaka, Komatsu Hiroshi, Ohba Tetsuhiko, Ohki Kazuo  Meeting abstracts of the Physical Society of Japan  52-  (2)  89  -89  1997/09/16
• 6a-P-7 AFM observation of impurity adsorption on lysozyme crystals.

  Makada T., Miyashita S., Sazaki G., Komatsu H.  Meeting abstracts of the Physical Society of Japan  52-  (2)  89  -89  1997/09/16
• 6a-P-9 In-situ observation of the concentration gradient around protein crystals under high pressure.

  Nagatoshi Yukiko, Sazaki Gen, Suzuki Yoshihisa, Miyashita Satoru, Nakada Toshitaka, Komatsu Hiroshi  Meeting abstracts of the Physical Society of Japan  52-  (2)  89  -89  1997/09/16
• Effect of Magnetic field on the crystallization of hen egg-white lysozyme

  YANAGIYA Shin-ichiro, SAZAKI Gen, MIYASHITA Satoru, NAKADA Toshitaka, KOMASTU Hiroshi, WATANABE Kazuo  Journal of the Japanese Association of Crystal Growth  24-  (2)  119  -119  1997/07/01  

  We crystallized HEW lysozyme under the magnetic field of 1-10T. The magnetic field drastically affected the habit of tetragonal lysozyme crystal. We tried to explain the habit change by using solubility change caused by the magnetic field. The effect of the magnetic field on the growth rate will be also discussed.
• Morphodrom of Hourse Spleen Ferritin Crystal

  SAZAKI Gen, YOSHIDA Eriko, NAKADA Toshitaka, MIYASHITA Satoru, KOMATSU Hiroshi, NIMURA Nobuo  Journal of the Japanese Association of Crystal Growth  24-  (2)  105  -105  1997/07/01  

  We studied the crystallization of horse spleen ferritin. The size of a ferritin molecule is 13 nm in diameter, and the molecule has very high symmetry (F432). Morphology of the ferritin crystal was drastically changed with the changes in the supersaturation and the type and concentration of impurities. The mechanism of the morphology change will be discussed.
• In-situ observation for nucleation of Taka-amylase A

  OHEDAI Tadashi, UENO Satoru, YANO Junko, SATO Kiyotaka, SAZAKI Gen, MIYASHITA Satoru, KOMATSU Hiroshi, MATSUURA Yoshiki  Journal of the Japanese Association of Crystal Growth  24-  (2)  106  -106  1997/07/01  

  We studied a nucleation of Taka-arnylase A (TAA).TAA was purificated TAA from Sumizyme and crystallized it from Tris-HCI buffer. A bipyramid crystal form was obtained under the condition of the previous study 1). Solubiity fo TAA was measured T.B.I. method. It was convinced that the solubirity of TAA was significantly high cornpared with lysozyme and strongry depended on temperature.
• Impurity effects on growth kinetics of tetragonal lysozyme crystals

  NAKADA T., SAZAKI G., MIYASHITA S., KOMATSU H.  Journal of the Japanese Association of Crystal Growth  24-  (2)  102  -102  1997/07/01  

  In-situ atomic force microscopy has been employed to investigate the surface structure of growing lysozyme crystals in aqueous solutions with various impurity concentrations.In high purity(>99.9%) lysozme solution.which was purified by high pressure liquid chromatography. the(101)surface showed welldeveloped flat terraces with molecular height steps,while the surface in lower purity solution was covered with a number of impurity particles.
• In-situ observation of the concentration gradient layer around an L-leucine complex crystal

  HASEGAWA Kazuhiro, MIYASHITA Satoru, SAZAKI Gen, NAKADA Toshitaka, SANO Chiaki, KOMATSU Hiroshi  Journal of the Japanese Association of Crystal Growth  24-  (2)  117  -117  1997/07/01  

  We measured the concentration gradient layer around a growing L-leucine complex crystal in order to clarify the effect of the solution flow on the crystal growth. With this result and observation of the surface growth morphology, we will discuss the growth mode change introduced by the flow.
• In-situ observation of the solution growth of Nd123

  NAKAYAMA M, NISHIMURA Y, MIYASHITA S, NAKADA T, SAZAKI G, KOMATSU H  Journal of the Japanese Association of Crystal Growth  24-  (2)  242  -242  1997/07/01  [Not refereed][Not invited]
   

  Crystallization of NdBa_2Cu_30_<7-8>crystals from high temperature solutions was observed in-situ. Changjng the supersaturation we could observed the morphologjcal change of the crystal shape. And measurement of the nucleation temperature enabled us to estimate the metastable region for nucleation.
• 28a-G-13 AFM observation of growing lysozyme crystals.

  Nakada T., Miyashita S., Sazaki G., Komatsu H.  Meeting abstracts of the Physical Society of Japan  52-  (1)  101  -101  1997/03/17
• 28a-G-10 Crystal growth of L-leucine complex in the flow system of solution

  Hasegawa Kazuhiro, Miyashita Satoru, Nakada Toshitaka, Sazaki Gen, Sano Chiaki, Komatsu Hiroshi  Meeting abstracts of the Physical Society of Japan  52-  (1)  101  -101  1997/03/17
• 28a-G-12 Solubility measurement of lysozyme crystals and its thermodynamical interpretation

  SAZAKI G., KURIHARA K., NAKADA T., MIYASHITA S., KOMATSU H., Matsuura Y.  Meeting abstracts of the Physical Society of Japan  52-  (1)  101  -101  1997/03/17
• Growth of superconducting oxide crystals from the high-temperature solution by the change of oxygen partial pressure

  Nishimura Y., Takemoto J, Miyashita S., Sazaki G., Nakada T., Komatsu H.  Abstracts of the meeting of the Physical Society of Japan. Sectional meeting  1996-  (2)  4  -4  1996/09/13
• Atomic force microscopy of Cu(III)electrode in perchloric acid solution

  Kinoshita Yusuke, Nakada Toshitaka, Miyashita Satoru, Sazaki Gen, Komatsu Hiroshi  Abstracts of the meeting of the Physical Society of Japan. Sectional meeting  1996-  (2)  3  -3  1996/09/13
• Relation between the refractive index and the growth rate of a tetragonal lysozyme crystal.

  KURIHARA Kazuo, MIYASHITA Satoru, SAZAKI Gen, NAKADA Toshitaka, KOMATSU Hiroshi  Abstracts of the meeting of the Physical Society of Japan. Sectional meeting  1996-  (2)  1  -1  1996/09/13
• Oxidation process of Au(III)in sulfuric acid solutions.

  Nakada T., Nishizawa T., Kinoshita Y., Sazaki G., Miyashita S., Komatsu H.  Abstracts of the meeting of the Physical Society of Japan. Sectional meeting  1996-  (2)  3  -3  1996/09/13
• Effect of Magnetic field on the nucleation and orientation of hen egg-white Lysozyme crystals

  YANAGIYA Shin-ichiro, SAZAKI Gen, MIYASHITA Satoru, NAKADA Toshitaka, KOMATSU Hiroshi, WATANABE Kazuo  Abstracts of the meeting of the Physical Society of Japan. Sectional meeting  1996-  (2)  1  -1  1996/09/13
• Growth of superconducting oxide crystals from the high-temperature solution by the change of partial oxygen pressure

  NISHIMURA Yoshihiro, NAKAYAMA Masao, MIYASHITA Satoru, NAKADA Toshitaka, SAZAKI Gen, KOMATSU Hiroshi  Journal of the Japanese Association of Crystal Growth  23-  (3)  134  -134  1996/07/10
• Kinetics of the surface steps on a tetragonal lysozyme crystal

  NAKADA T, MIYASHITA S, SAZAKI G, KOMATSU H  Journal of the Japanese Association of Crystal Growth  23-  (3)  132  -132  1996/07/10
• High resolutional observations of protein surfaces bu atomic force microscopy

  NAKADA T., SAZAKI G., MIYASHITA S., KOMATSU H.  Journal of the Japanese Association of Crystal Growth  23-  (3)  220  -220  1996/07/10
• Effect of Magnetic Field on the Nucleation and Orientation of protein crystals

  SAZAKI Gen, YOSHIDA Eriko, NAKADA Toshitaka, MIYASHITA Satoru, KOMATSU Hiroshi, AWAJI Satoshi, WATANABE Kazuo, MOTOKAWA Mitsuhiro  Journal of the Japanese Association of Crystal Growth  23-  (3)  286  -286  1996/07/10
• Determination of the liquidus of the NdBa_2Cu_3O_<7-δ> system by in-situ observation

  NAKAYAMA M., NISHIMURA Y., MIYASHITA S., NAKADA T., SAZAKI G., KOMATSU H.  Journal of the Japanese Association of Crystal Growth  23-  (3)  275  -275  1996/07/10
• Formation of visinal face and its growth mechanism of concanavalin A crystal

  SAZAKI Gen, KASHIMOTO Eigo, NAKADA Toshitaka, MIYASHITA Satoru, KOMATSU Hiroshi  Journal of the Japanese Association of Crystal Growth  23-  (3)  285  -285  1996/07/10
• 31p-PSB-7 Atomic force microscopic observations of the liquid structure near the solid-liquid interface II.

  Nakada T, Miyashita S, Sazaki G, Komatsu H, Chernov A.A.  Abstracts of the meeting of the Physical Society of Japan. Annual meeting  51-  (2)  483  -483  1996/03/15
• 31a-B-2 Solubility measurement of protein crystals by Interferometry

  SAZAKI Gen, KURIHARA Kazuo, MIYASHITA Satoru, NAKADA Toshitaka, KOMATSU Hiroshi  Abstracts of the meeting of the Physical Society of Japan. Annual meeting  51-  (2)  1  -1  1996/03/15
• 29p-PSB-19 Atomic force microscopic observations of the liquid structure near the solid-liquid interface

  Nakada T., Miyashita S., Komatsu H., Chernov A.A.  Abstracts of the meeting of the Physical Society of Japan. Sectional meeting  1995-  (2)  497  -497  1995/09/12
• Crystal Growth of Lectin Protein Concanavalin A

  KASHIMOTO Eigo, SAZAKI Gen, KOMATSU Hiroshi  Journal of the Japanese Association of Crystal Growth  22-  (3)  137  -137  1995/07/10
• The surface morphology of a lysozyme crystal

  Sakuma Kazuki, Miyashita Satoru, Nakada Toshitaka, Sazaki Gen, Komatsu Hiroshi  Abstracts of the meeting of the Physical Society of Japan. Annual meeting  50-  (2)  15  -15  1995/03/16

Industrial Property Rights

• 光学顕微鏡と光学的観察方法

  特開2005-309415
• 有機半導体薄膜のエピタキシャル成長

  特開2005-79535A
• 水素生成光デバイス

  特開2003-238104

Awards & Honors

• 2009/11 Japanese Association for Crystal Growth The 26th Best Paper Award
   Development of advanced optical microscopy and elucidation of growth mechanisms of protein crystals at the molecular level 

  受賞者: SAZAKI Gen
• 2003/10 The Japan Society of Microgravity Application The 1st Young Scientist Award
   Effects of external fields on protein crystallization 

  受賞者: SAZAKI Gen

Research Grants & Projects

• Presumption of statistical mechanical state distribution of 3D protein structure in solution states by crystallization

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2021/04 -2024/03 

  Author : 鈴木 良尚, 佐藤 正英, 佐崎 元

   

  「研究実施計画」において、初年度はニワトリ卵白リゾチーム（HEWL）斜方晶系結晶を使って、NaCl濃度を細かく刻んで結晶化し、Na+サイト周辺で、変化する電子密度のNaCl濃度依存性を明らかにする予定であったが、塩濃度の変化による構造変化よりも、温度変化による構造変化の効果が圧倒的に大きいという予定外の事実が判明したため、急遽確認作業に追われた。2022年度に実験を予定していて、予備実験を実施していたグルコースイソメラーゼ（GI）について、沈殿剤フリーの遠心濃縮によって得られた結晶を、SPring-8において90 Kで構造解析して得られた構造と、Protein Data Bank（PDB）に登録されている、硫酸アンモニウムによる塩析で得られた結晶による1XIBという構造を比較したところ、構成分子の平均二乗変位（RMSD）が0.234Åであった。それに対して、研究室線源で100 Kで構造解析した沈殿剤フリー結晶で得られた構造のとの間のRMSD は 0.075Åであったため、塩濃度による違いが明らかに出たと思っていた。ところが、念のため、硫酸アンモニウムの塩析結晶における構造の一つである4A8Iと比較したところ、RMSD = 0.072Åとなり、塩濃度による違いはなかった。4A8Iは100 Kで構造解析していたため、温度変化の方がはるかに大きかった。これらの結果から、再現性の良い、常温における沈殿剤フリーのタンパク質結晶構造解析法が必要となり、その過程で、蒸発によるタンパク質の新規結晶化法を開発できたためCrystals誌に論文化した。 また、タンパク質分子の単純化モデルとしてパッチ粒子の相互作用と結晶構造の相関について、シミュレーションした結果をScientific reports, Japanese Journal of Applied Physics誌に投稿した。
• Exploring general nature of interfacial melting on ice crystals: in situ approach by optical microscopy

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2021/04 -2024/03 

  Author : 村田 憲一郎, 佐崎 元

   

  令和3年度は，主に①正立型レーザー共焦点微分干渉顕微鏡（LCM-DIM）システムの構築とLCM-DIMによる一分子段差の検出，および②全反射照明を組み込んだ氷成長観察チャンバー（正立用）の開発に取り組んだ．以下にその概要を記す．
  ①正立型LCM-DIMの構築後，標準試料として石膏とシリコンカーバイトの結晶表面を観察し，両サンプルにおいて一分子段差（それぞれ，0.76nm，0.5nm）の観察に成功した．当初の計画通り，既存のLCM-DIM（オリンパス社製）と同等の高さ分解能を達成しつつ，時間分解能を上回る性能を得られた．加えて，Zeiss社の独自技術である円偏光微分干渉顕微鏡（C-DIC）の共焦点化にも取り組んだ．通常の微分干渉顕微鏡は，段差コントラストに異方性を持ち，特定方向のコントラストが落ちることが知られている．従来のLCM-DIMにおいても同様の弱点があり，コントラストの弱い単位ステップのダイナミクスをその場観察する上で弊害となり得る．一方，C-DICでは円偏光を用いることで，コントラストの異方性を任意の方向に制御することが可能である．今回の研究により，C-DICの共焦点化に成功し，Åオーダーの高さ分解能を維持しつつコントラストの異方性を任意に調整することが可能となった．
  ②倒立型顕微鏡用にプロトタイプとして作成していた全反射照明系氷成長観察チャンバーを改良し，正立型LCM-DIMで使用できるようにした．これにより，次年度にシングルフォトン検出器を導入次第，直ちに微粒子からのエバネッセント光の散乱を観察できる段階に入った．
• 多結晶氷の表面融解機構の解明

  平成31年度科学研究費補助金，基盤研究(B)

  Date (from‐to) : 2019/04 -2022/03 

  Author : 佐﨑 元
• Crystallization and crystallography of proteins at in vivo salt concentrations

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2018/04 -2021/03 

  Author : SUZUKI Yoshihisa

   

  We have clarified significant structure changes in three-dimensional structure of protein molecules in crystals from different growth conditions. We studied effects of the difference in precipitant condition on the structure, and published papers on the result. In addition, in dilute precipitant conditions, liquid-liquid phase separation frequently occurred during centrifugal concentration of solutions. In the dense liquid phase after the separation, nucleation and growth of crystals occurred very rapidly. Growth rates of obtained crystals in the dense liquid were at least an order of magnitude faster than those in conventional salting-out conditions. In spite of such very rapid processes, maximum resolution limits of obtained crystals were very high (less than 0.1 nm, for instance).
• Communication of insects through body surface lipids: proposal of a new mechanism employing mechanoreceptors

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2018/06 -2020/03 

  Author : Kaneko Fumitoshi

   

  The outermost layer of insects is a very thin layer (0.1-1 μm) of hydrocarbons. In addition to their barrier functions to adopt the environment, the body lipid is used for the communication between insects. Although it is the common view that insects communicate each other by detecting the difference in the chemical composition of the body lipid by using chemical sensors on antennae, we have postulated the possibility that insects also detect the difference in the physical properties by mechanical sensors. To inspect the validity of this postulation, the body lipid of the field cricket, which shows a gender gap in composition, has been studied with respect to the structure and properties at in-situ on body surfaces by using atomic force microscopy (AFM) and other methods. The friction force detected by AFM is clearly different between male, female, and degreased body surfaces, which strongly suggests that such differences are detected by the mechanical sensor systems of insects.
• Anisotropic function of antifreeze protein for ice crystal growth - To elucidate growth promotion and inhibition mechanism

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2014/04 -2018/03 

  Author : FURUKAWA Yoshinori

   

  Growth experiments of an ice crystal in a supercooled solution of antifreeze protein were carried out and separately measured the growth rates for the basal and prism faces. We clarified that the growth of basal faces was enhanced by the effect of antifreeze protein, while the growth of prism faces was suppressed. It means that the effects of antifreeze proteins for ice crystal growth were different for every crystallographic faces. The growth promotion of basal face was explained by a new model that the adsorbed antifreeze protein molecules on the edges of growth steps may work as the new sources to generate new growth steps on the basal faces. We clarified that the mechanism for the freezing inhibition of living organisms under the sub-zero temperature environments was compatibly explained on the basis of the anisotropic functions of antifreeze proteins for ice crystal growth.
• 不凍タンパク質が示す相互作用の解明：拡散・吸着ダイナミクスの蛍光１分子計測

  平成28年度科学研究費補助金，挑戦的萌芽研究

  Date (from‐to) : 2016/04 -2018/03 

  Author : 佐﨑 元
• 結晶表面上の化学反応を可視化する：氷表面上での酸性ガスの吸着・融解反応の解明

  平成27年度科学研究費補助金，基盤研究(A)

  Date (from‐to) : 2015/04 -2018/03 

  Author : 佐﨑 元
• Melt-like growth of protein crystals

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2014/04 -2017/03 

  Author : Suzuki Yoshihisa

   

  Salt-free protein crystallization method with centrifugal concentration apparatus has been developed. With this method, nucleation of hen egg-white lysozyme (HEWL) crystals occurs in hyper-concentrated liquid phase obtained by liquid-liquid phase separation during centrifugal concentration processes. We could successfully observed molecular steps on the obtained crystal surface. Three-dimensional structure of lysozyme molecule obtained in this method is significantly different from that obtained by normal salting-out method.
• Development of label-free and quantitative imaging of cell adhesion

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2014/04 -2016/03 

  Author : YOSHIKAWA Hiroshi, SAZAKI Gen

   

  In this work, a high-contrast and quantitative imaging method of cell adhesion has been developed by improving instruments and analysis of optical interferometry. In addition, the new method was applied to the study of the quantitative correlation between adhesion and functions of various cells. In particular, the method provided the first quantitative insights into the correlation between adhesion and metastatic ability of cancer cells, which clearly shows the potential of this method for the applications to label-free screening of cell adhesion.
• Computer Simulation on Creative Development of Fusion Materials through Molecular Control

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2010/04 -2015/03 

  Author : NADA Hiroki, SAZAKI Gen

   

  In this study, attention was paid to the fact that the crystallization of minerals in organisms (biomineralization) is precisely controlled by additives, such as proteins, peptides and polymers. For several topics concerning the crystallization control of calcium carbonate, which is a representative mineral in biomineralization, we elucidated the mechanism of the crystallization control by additives using a computer simulation method at the molecular scale. An important conclusion derived from this study is that water at the crystal surface is crucial in the crystallization control. This study contributed to the creative development of fusion materials by providing fundamental knowledge obtained in this study for experimental groups concerning the design of functional molecules and materials synthesis in the fusion materials project.
• 高分解光学観察による氷結晶表面での疑似液体層の動的挙動の解明

  平成23年度科学研究費補助金，基盤研究(A)

  Date (from‐to) : 2011/04 -2015/03 

  Author : 佐﨑 元
• 水−氷（融液−結晶）界面の分子レベル直接観察：超高感度位相差顕微鏡の開発

  平成24年度科学研究費補助金，挑戦的萌芽研究

  Date (from‐to) : 2012/04 -2014/03 

  Author : 佐﨑 元
• Static and kinetic effect of impurities on instability of shape of crystal

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2011 -2013 

  Author : SATO Masahide, SAZAKI Gen, SUZUKI Yoshihisa, KATSUNO Hiroyasu

   

  We studied effects of impurities attached to a surface from theoretical and experimental points of view. We showed that increasing of the diameter of 2-dimensional island-like crystal is caused by impurities. Carrying out Monte Carlo simulation, we studied motions of steps on a vicinal face during bunching induced by impurities. We also showed the possiblity of increasing the diffusion coefficient of 2-dimensional island like crystal due to impurities. We tried to study the effect of impurities in solid on behaviors of 2-dimensional island-like crystal, which is caused by long range interaction, and to form an alloy of 2 types of proteins. We cannnot obtain clear conclusioins about The studies, so we continue studying these themes.
• 不凍タンパク質作用発現機構の解明を目指したその場光観察

  科学技術振興機構：戦略的創造研究推進事業さきがけ

  Date (from‐to) : 2008/10 -2012/03 

  Author : 佐﨑 元
• 分子レベルその場観察によるタンパク質結晶へのマイクロ欠陥取り込み機構の解明

  平成18年度科学研究費補助金，基盤研究(B)

  Date (from‐to) : 2006/04 -2009/03 

  Author : 佐﨑 元
• Anisotropic dynamics of ice growth promotion and its self-oscillation induced by the interfacial adsorption of biological macro molecules

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2006 -2009 

  Author : FURUKAWA Yoshinori, SAZAKI Gen, KATAGIRI Chihiro, YOKOYAMA Etsuro, NADA Hiroki, KANEKO Fumitoshi

   

  Experimental and theoretical studies of antifreeze proteins, which have the special function to prevent the freezing of living organisms under the subzero environment, were carried out. Direct evidence for the relation between the adsorption of proteins on the ice interfaces and the prohibition of crystal growth was first demonstrated directly, and it was made clear that the protein molecule adsorption proceeded in two stages depending on the conformation change of protein molecules. This adsorption mode was completely new and called as "two-step reversible adsorption". This adsorption model also explained the growth promotion of basal planes of ice and the self oscillations of growth rates.
• X線導波路現象を利用した有機薄膜高次構造のリアルタイム観測

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2006 -2008 

  Author : 林 好一, 佐崎 元

   

  放射光実験施設Photon FactoryのBL3Cにおいて、白色X線を用いたX線導波路の実験を行った。ここでは、Si/PMMA/Siの多層膜を作製し、白色X線を薄膜試料に照射し、薄膜端面から放出されるX線をエネルギー分散型X線検出器によって観測した。PMMA層においてX線の共鳴現象を起こすため、薄膜端面からのX線は分光され、TE(transverse electric)0、TE1、TE2の3つの共鳴モードのピークを観測することができた。また、これらのピークのエネルギー値は、薄膜の高次構造に大きく影響されるため、エネルギー値を解析することによって、薄膜の膜厚、密度を精度よく決定することができる。さらに、本年度は、リアルタイムで、X線導波路現象によるX線スペクトルの変化を観測することによって、薄膜の高次構造の素早い時間変化を追うことを試みた。一つのスペクトルの測定時間は10秒である。上記試料に対し、強力な放射光白色X線を照射することにより、即座に試料の変性が開始され、約200秒後に短時間で、その変化が完了することがわかった。ここでは、特に、TE2のピークのシフト量がTEOのものより大きいことが特徴的であった。このことより、PMMA層の密度は大きく変化せず、膜厚のみが変性したことが示された。標準のX線反射率測定装置も用い、詳細に解析した結果、元々膜厚100nm程度であったものが、約10%程度小さくなり90nm程度になることが観測された。今回の実験から、白色X線を用いたX線導波路現象による分光X線の観測が、薄膜高次構造のリアルタイム観測に非常に有望であることが判明した。
• Crystal Growth of Snow and Ice

  Date (from‐to) : 2008
• タンパク質結晶-溶液界面におけるタンパク質１分子の吸着・脱離・拡散ダイナミクス

  平成17年度科学研究費補助金，特定領域研究（公募研究）

  Date (from‐to) : 2005/04 -2007/03 

  Author : 佐﨑 元
• Study of atomistic diffusion, nucleation and cluster formation process of atoms and molecules

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2005 -2007 

  Author : SUTO Shozo, SAZAKI Gen, YAMADA Taro, HAYAKAWA Yoshinori

   

  Recently, it is possible to observe atomistic motion of single atoms or single molecules on solid surfaces due to the development of surface probe microscopy, in particular scanning tunneling microscopy (STM). First goal of this study is to understand a cluster formation process from atomistic diffusion of single atoms, just after deposition up to 8 hours. We observed the atomistic motion of Ag atoms on a Si(111)7x7 surface and the formation process of (Ag)n clusters in a 7x7 surface potentials. It is found that the diffusion is cooperative where the hopping rates depend on the nearest neighbor sites. We also measured the tunneling spectroscopy and found that the n=5 and 6 clusters have a specific electronic energy level: Second goal is to investigate the weakest interaction between substrate and the adsorbate atoms or molecules. We observed two -epitaxial structures of pentacene polycrystalline thin film crystals on a hydrogen-terminated Si(111) surface and commensurabilites. Furthermore, we observed the step-induced anisotropic growth of pentacene thin film crystals on a hydrogen-terminated Si(111) surface. In the early stage of this study, we proposed the process for ultra-clean and atomically controlled hydrogen-terminated Si(111)-(1x1) Surface and it is revealed by high resolution electron energy loss spectroscopy, atomic force microscopy and scanning tunneling microscopy. We also propose the deuterium terminated Si(111) surface and observed the surface phonons. Third goal is to investigate the strong interaction between substrate and the adsorbate atoms. Formation process and surface structure of platinum silicide thin layers was studied using STM. Now, we are able to manipulate the single atom or molecule and, then, we try to estimate the cluster size and the electronic structure. Our final goal is to understand the cluster formation process, surface reaction and to form an electronic devices in the atomic scale.
• 蛍光顕微法を用いた有機半導体薄膜結晶粒間の位相欠陥イメージング

  平成16年度科学研究費補助金，萌芽研究

  Date (from‐to) : 2004/04 -2006/03 

  Author : 佐﨑 元
• タンパク質結晶成長素過程の１分子その場観察による格子欠陥取り込み機構の解明

  平成16年度科学研究費補助金，基盤研究(B)

  Date (from‐to) : 2004/04 -2006/03 

  Author : 佐﨑 元
• 環境型バイオデバイス創製のための有機・無機ヘテロエピタキシャル結晶成長技術の開発

  財団法人稲盛財団：平成13年度研究助成

  Date (from‐to) : 2001/04 -2002/03 

  Author : 佐﨑 元
• 強磁場下でのタンパク質結晶周囲の濃度場観察

  平成12年度科学研究費補助金，奨励研究(A)

  Date (from‐to) : 2000/04 -2002/03 

  Author : 佐﨑 元
• Research on functional electronic devices based on straind-Si on SiGe alloy substrates

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2001 -2002 

  Author : USAMI Noritaka, KOH Shinji, NAKAGAWA Kiyokazu, NAKAJIMA Kazuo, UJIHARA Toru, SAZAKI Gen

   

  The purpose of this research is to realize strain-controlled Si-based heterostructures with superior electronic properties on homemade SiGe substrates wish uniform Ge composition. Firstly, we tried to develop a feedback control system of the crystal-melt interface position and temperature based on in-situ monitoring system. Automatic recognition of the interface position was successful by binarization and differentiation of the CCD image. By utilizing newly developed system, we succeeded in growing SiGe with uniform composition. To improve the crystal quality, we systematically changed the temperature gradient at around the crystal-melt interface. At a result, systematic decrease of the line-width of the X-ray rocking curve and increase of the intensity were confirmed presumably due to the suppression of constitutional supercooling. In addition, crystal quality was found to be strongly dependent on the orientation of the seed crystal. On homemade SiGe, modulation doped structure with strained-Ge channel was grown by molecular beam epitaxy. Although improved carrier mobility was not achieved, controllability of strain was confiemed.
• 過冷炉度を制御した融液成長法による太陽電池用Si多結晶の大粒径化と高効率化

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 2001 -2002 

  Author : 中嶋 一雄, 宇治原 徹, 佐崎 元, 宇佐美 徳隆, 北原 邦紀, 藤原 航三

   

  研究目的:多結晶シリコンは実用太陽電池材料として利用されているが単結晶材料に比べてエネルギー変換効率が低い。その原因として、結晶粒界や転位や不純物など結晶欠陥の影響が考えられている。このような結晶欠陥は融液成長時に導入されるが、その制御方法は確立されていない。本研究では融液成長時の過冷度を精密に制御して成長を行い過冷度や潜熱と結晶欠陥および結晶粒径の相関を解明する。 本年度の実績:本年度は融液成長過程および成長温度を同時に観察できる装置を設計・導入した。本装置は観察窓付きの一方向成長特殊小型炉と赤外線放射温度計を組み合わせた装置である。小型炉は高真空に引いた後アルゴンガス置換でき、冷却速度および炉内温度を精密制御できる。また、冷却ガスによる強制冷却機構と種付け機構を有する。さらに示差熱検出機構を有している。放射型温度計は顕微機構を有し、赤外と同時に高速度CCDカメラで可視像を観察できるため、成長過程と温度を同時に測定できる。試料サイズは10×15×5mm^3程度であり、成長後組織解析を行うのに十分な大きさである。 予備実験としてレーザー顕微鏡とイメージ炉を組み合わせた装置を用いてシリコンの融液成長過程をその場観察した。φ3×2mm^3の試料を融解後さまざまな速度で冷却し界面の形態および成長速度を実測した。3K/minで冷却した試料の成長界面はplanar界面であったが25K/min、40K/min、および45k/min冷却した試料ではfacet界面であった。定常状態における成長速度はplaner界面ではV【less than or equal】30μmであったがfacet界面では150μm【less than or equal】V【less than or equal】390μmであった。また非定常状態ではfacet面の消滅過程も観察された。非定常状態ではさまざまなfacet面が形成されたが(111)facet以外の面は消滅し、定常状態では(111)facetのみ形成した。また、赤外線カメラを用いてfacet界面前方の温度測定を行った。界面前方の過冷度はおよそ7度であった。
• Development of advanced optical microscopy

  Date (from‐to) : 2002
• 磁場を利用した微小重力下でのタンパク質の結晶化

  財団法人日本宇宙フォーラム：平成10年度宇宙環境利用に関する公募地上研究 フェーズIA

  Date (from‐to) : 1998/10 -2001/03 

  Author : 佐﨑 元
• 磁場中の溶液挙動の解明とそれを用いたタンパク質の良質結晶育成

  日本原子力研究所：黎明研究

  Date (from‐to) : 2000/04 -2001/02 

  Author : 佐﨑 元
• 磁場によるタンパク質の高品位結晶育成

  平成10年度科学研究費補助金，基盤研究(B)

  Date (from‐to) : 1998/04 -2000/03 

  Author : 佐﨑 元
• Research on spatially and temporally resolved spectroscopy of semiconductor quantum structures by using ulta small probe light

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1999 -2000 

  Author : USAMI Noritaka, UJIHARA Toru, SAZAKI Gen, NAKAJIMA Kazuo, SHIRAKI Yasuhiro

   

  In this project, we have tried to establish spectroscopic technique to evaluate microscopic interface roughness, and to characterize inherent optical properties of quantum structures without being affected by structural fluctuations. As a technique, we exploited to combine local probe spectroscopy to use objective lens for microscope and lithography technique to fabricate small window on top of the sample, leading to improved spatial resolution. We selected quantum structures made from compound semiconductors, which are studied to improve electrical and optical device performance. By reducing the feature sizes such as quantum wires and quantum dots, the impact of the size fluctuations on the properties becomes significant. This explains why we selected the quantum structures. We found that localized excitons trapped by some microscopic potential fluctuations in InGaAs/GaAs quantum wells, which are not detected by macroscopic photoluminescence, can be detected by our technique. By measuring growth teroperature dependence, we clarified that the increase of the growth temperature lead to the deterioration of the interface abruptness due to the In surface segregations, however, the interface roughness is improved compared to the sample grown at lower temperatures. In addition, we succeeded in observing charged excitons in quantum dots and controlling the charged states by applying electric field to modulation-doped quantum dots. Furthermore, we tried to create novel quantum structures to insert ultra thin film as a localized center for electrons, and succeeded in improving drastically improve the luminescence efficiency of indirect semiconductors, and we found that stacking of quantum dots greatly modify the growth mode. As a next step, we will apply our spectroscopic technique to these quantum structures and clarify their microscopic structures and mechanisms for improved luminescence efficiency.
• Development of multicomponent bulk single crystal with uniform composition by the multicomponent zone-melting method

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1999 -2000 

  Author : NAKAJIMA Kazuo, UJIHARA Toru, SAZAKI Gen, USAMI Noritaka, ISHIKAWA Hiroshi, MIYASHITA Satoru

   

  In this project, we have tried to establish a technology to grow multicomponent semiconductor bulk crystals with uniform composition, which are expected to lead to the creation of new functional heterostructures by greatly widening the choices of lattice constant and band gap of semiconductor substrates. By utilizing the technology, we have grown SiGe bulk crystals. In Fy1999, we designed new growth system equipped with an in-situ monitoring system of the position and the temperature at the growth interface. The system includes a quartz slit which allows an optical access, and a CCD camera to observe the position of the interface, and a thermoviewer to obtain the temperature distribution. In addition, the information can be used to control the pulling rate of the ampoule for the crystal growth. Therefore, precise control of the growth temperature is possible. The starting materials for the SiGe bulk crystal are a Si single crystal as a source, polycrystalline Ge, and Ge (100) single crystal as a seed. By putting the ampoule in an appropriate temperature gradient, polycrystalline Ge and a top part of Ge single crystal are melted to prepare a growth melt. Then, Si dissolves into Ge melt and Si atoms are carried to the interface, mainly by diffusion originating from the concentration gradient, and also by possible influence of convection. Consequently, the supercooling is formed around the growth interface and a driving force for the growth of SiGe crystal is established. By monitoring the interface position during the growth with fixed ampoule, we obtained the growth rate of the crystal. By pulling down the ampoule balanced with the growth rate, we succeeded in growing SiGe with fixed interface position. The pulling down the ampoule was confirmed not to affect the temperature distribution. In other words, SiGe was grown under fixed growth temperature. In fact, EDX analysis clarified that the composition of the crystal is uniform over 20mm. As a next step, we will apply this technique to various material system, and perform epitaxial growth on our original substrates to create new functional heterostructures.
• 磁場によるタンパク質の高品位単結晶育成

  日本原子力研究所：黎明研究

  Date (from‐to) : 1998/04 -1999/02 

  Author : 佐﨑 元
• タンパク質分子の等電点の新測定法と電極界面凝集化過程のその場観察

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1999 -1999 

  Author : 宮下 哲, ダービン・ステファン デュエン, 佐ざき 元, 中嶋 一雄

   

  タンパク質のような両性イオンの溶液内での挙動を理解するとき、等電点は重要な物理量である。特にタンパク質の吸着・凝集・結晶核形成では、凝集力を評価する鍵になる。タンパク質分子の基板への吸着は、分子の等電点・基板の電位・溶液水素イオン濃度と密接に関係しているはずである。本研究は、電気化学原子間力顕微鏡を使い、タンパク質溶液内に置いた導電性の基板の観察を行い、電位変化に対する像の様子から等電点を決める新手法の開発を目指した。 研究では、等電点の分かっている卵白リゾチーム(等電点=11)水溶液を使い、この中に置いた高配向グラファイト基板上へのタンパク質分子の吸着の様子を観察した。リゾチームの等電点は11であるため、溶液の水素イオン濃度が11よりも大きいと分子は負に帯電し、逆に11よりも小さいと正に帯電する。従って、水素イオン濃度が11よりも小さい溶液を用意し、基板電位を負にすると、タンパク質分子は基板に吸着するはずである。実験では未飽和の水素イオン濃度5のリゾチーム溶液を使用した。電位を0の状態にして、まず基板のμmサイズの明瞭な表面像を得た。この状態から基板電位を低下させたところ、ある電位を境に像が不明瞭となった。この状態から電位を上げると再び基板表面像が得られたが、以前ほどは明瞭ではなくなっていた。また、基板表面像が得られた電位は像が不明瞭になった電位よりも高かった。このことはある基板電位よりも下でリゾチーム分子が基板に吸着したことを示しており、吸着電位と溶液水素イオン濃度から等電点を求めることが可能であることが明らかになった。臨界電位と水素イオン濃度の関係を求めるのが次の課題であるが、そのためには再現性良く臨界電位を求める手順を決めることが必要である。また、水の電気分解のため使用できる電位幅に制限が存在する。水素イオン濃度を適当な幅で変えて観察を行うことが必要になってくる。
• In situ study of protein crystallization at the molecular level using atomic force microscopy

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1998 -1999 

  Author : DARBIN Stephen d., SAZAKI Gen, MIYASHITA Satoru

   

  The goal of this work has been to extend the investigation of protein crystallization mechanisms to the level of individual molecules. Within this area, the research followed several directions : 1) use of atomic force microscopy (AFM) to follow the kinetics of protein crystal growth in situ, relating the observable parameters such as step velocity to molecular scale quantities such as bond energies ; 2) development of a modification of the conventional AFM technique to directly monitor single-molecule events during crystal growth, such as surface diffusion and incorporation ; 3) use of optical techniques to monitor properties which might be related to molecular level phenomena, such as alignment effects due to extremely high magnetic field, or changes in molecular hydration under high pressure. In addition, other research on crystal growth was carried out using the AFM and therefore considered to be indirectly supported. Regarding 1), AFM observation was used to elucidate the mechanism of impurity action in inhibiting crystal growth of tetragonal form lysozyme, which can be understood in terms of a step-blocking model. AFM was also used to investigate the kinetics of step motion on monoclinic lysozyme crystals, which could be related to the intermolecular "macrobonds" which determined the morphology of the crystal. In connection with 2), we developed a modified commercial atomic force microscope combined with a high-speed data acquisition system to pursue more direct single-molecule measurements. The AFM, operated in tapping mode without scanning, gave a signal representing sample height changes due to motion of the topmost protein molecule under the tip. A much improved signal-to-noise ratio can be obtained by using very small cantilevers ; with these, the system should be capable of the ultimate goal of single-molecule observation. As for area 3), fluorescence microscopy observations were used to demonstrate the role of molecular charge and crystal growth rate on impurity incorporation, and polarization rotation and in situ optical microscopy were used to study magnetic field effects, which could be understood via the observed reduction of solution convection, but had at most small influence on molecular-scale parameters such as alignment. Meanwhile, understanding of the action of ever-present impurities and means of optimizing crystal morphology through solution conditions and external fields have already enabled the production of higher quality crystals for structure determination at higher resolution
• Growth of single crystalline films of bismuth based oxide superconductors by the liquid phase epitaxy method

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1997 -1998 

  Author : MIYASHITA Satoru, SAZAKI Gen

   

  Growth conditions of Bi2212 superconducting films on the substrate crystal by the liquid phase epitaxial growth method using KCl as a solvent were investigated, In the case of the starting composition of Bi : Sr : Ca : Cu=2 : 2 : 1 : 2, the best growth temperature ranged from 840 to 870ﾟC.Under this condition, only the 2212 phase film grew on the substrate. In the early stage, the growth mechanism was the island growth and the changed to the continuous film growth mode. When islands met on the substrate, large steps occurred and this made film flattness poor. When we used the LaAlO3(1 10) substrate, however, grown 2201 films showed atomically flat area extending few micrometers square. When we used the NdGaO_3 * (001) substrate, nearly twin free film was obtained. Dessolution and solidification process of the oxide system of Bi-Sr-Ca-Cu-O was in situ observed with high temperature optical microscopy. We could determined the primary crystallization field (rough region of temperature and composition where the crystals grow as the first solid) for the self flux growth of the Bi based oxide superconductors system. This region we determined contained much bismuth than those ever reported. Traveling solvent floating zone method was applied on the basis of the knowledge of the primary crystallization field. To obtain single crystals thick in the crystallographic c-axis direction, the control of the nucleation by such as seeding was found to be needed. Using the seed crystal, we succeeded in continuous growth from the seed crystal and this indicated that the primary crystallization field we determined was reliable and useful. Next subject on the primary crystallization field is to clearly separate the 2212 phase and the 2201 phase region. We tried the liquid phase epitaxial method using the self flux, to fail. Corrosion of the substrates by the flux enabled us to obtaine the single film crystal. Further study is needed.
• 光干渉法を用いたタンパク質結晶化過程のその場観察

  住友財団：基礎科学研究助成

  Date (from‐to) : 1996/12 -1997/11 

  Author : 佐﨑 元
• 光干渉法による低接触角の新測定法

  日本学術振興会：科学研究費助成事業

  Date (from‐to) : 1997 -1997 

  Author : 小松 啓, 中田 俊隆, 宮下 哲, 佐崎 元

   

  本研究は光干渉法を用いて、濡れ性の良好な固体と液体の接触角の計測法を確立するとともに、液体の接触角測定で重要なパラメータである雰囲気と温度を制御し、この新手法のもつ可能性を開発することを目標とした。現有の光学顕微鏡に長焦点低倍率のMichelson型二光束干渉対物レンズを装着し、干渉縞を使って濡れ性の良い固体と液体の接触角の計測を行えるようにした。測定の結果、不透明な液滴の場合、3°以下、透明な液滴の場合、液体の屈折率がわかっている場合は5°以下の接触角が正確に計測できることが明らかになった。この方法の利点は、従来の液滴側面から計測する方法に比べて、1.濡れの良い場合の低接触角の高精度の測定 2.液滴の形状の対称性が必要とならない点がある。一方、短所としては、接触角がこの値よりも大きいときは、液滴上での干渉縞が密になることと、液滴表面からの反射光が顕微鏡の光路に戻ってこないため、像が暗くなり、測定困難となる。この点の改良が今後の課題である。 この装置に室温近くではペルチエ素子を使った温度セル、高温では光集光型の温度セルを使って接触角の測定を行った。特に対物レンズの焦点距離を長く(25mm)しているため、高温セルを使った測定が可能になっている。また、対象を酸化物を中心に考えているため、高温セルは雰囲気の酸素分圧を酸素メータと自動弁と調節器により自動制御できるようにした。これを使って白金基板上の酸化銅の接触角を計測した。1230℃で測定した場合、酸素分圧に対して45%付近で極小点をもつように変化した。また室温でグリセリン水溶液とマイカとの接触角を計測した。グリセリン濃度に対する接触角の変化を精密に測定できた。
• Nucleation and Growth Kinetics of Protein Crystals

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1997 -1997 

  Author : KOMATSU Hiroshi, VEKILOV Peter, ROSENBERGER Franz, SAZAKI Gen, NAKADA Toshitaka, MIYASHITA Satoru

   

  Results obtained by this project were summarized as below. (1) Japanese team developed a Michelson Interferometer objective lens of super-long working distance (25.5 mm) with Nikon Co. Using this interferometer, a novel technique for determining solubility was developed, and solubilities of tetragonal and orthorhombic lysozyme crystal were detemined as a function of temperature for the first time. (2) Japanese team studied magnetic field effects on the crystallization of lysozyme, and found that a magnetic field (i) increased a growth rate and (ii) decreased a solubility. Equipment to measure magnetic birefringence was developed. (3) Japanese team highly-purified commercial lysozyme (99.9%) by purification technique developed by U.S.A.team. Growthprocess of lysozyme crystals were in situ observed by atomic force microscopy. It was found that small amount of impurity (1%) drastically decreased growth rate of (101) face of tetragonal crystal. (4) Japanese team developed a novel technique to measure impurity content and its distribution in the crystal with a fluorescense indicator. A novel mechanism of the impurity incorporation into the crystal was proposed. (5) U.S.A.team analyzed the concentration distribution around growing lysozyme crystals using computer simulation technique. Japanese team measured the actual concentration distribution around the crystal by interferometry. These two results were compared each other and found that they mostly agreed. It was found that buoyancy driven convection can be stopped when the thickness of the solution is smaller than l50オm. (6) Japanese team observed the concentration distribution around lysozyme crystals under lg to micro-g using free fall facilities. The changes in the concentration distribution were analyzed.
• タンパク質（コンカナバリンA）の結晶成長過程の動的研究

  平成７年度科学研究費補助金，奨励研究(A)

  Date (from‐to) : 1995/04 -1996/03 

  Author : 佐﨑 元
• Nucleation and Growth Kinetics in Protein Crystallization

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1995 -1996 

  Author : KOMATSU Hiroshi, THOMAS Bill, VEKILOV Peter, ROSENBERGER Franz, SAZAKI Gen, NAKADA Toshitaka, MIYASHITA Satoru, OBINATA Masuo, MUSHOL Martin

   

  Achievements of this year are as follows ; 1. The Japanese group (J-group) measured solubilities of tetragonal, orthorhombic and triclinic form of hen egg white lysozyme (HEW lysozyme) using two beam interferometry. 2. J-group developed an interferometic method to measure the refractive index inside crystals (HEW lysozyme). 3. J-group got highly purified HEW lysozyme samples using HPLC.With this sample, they observed crystal interfaces using atomic force microscopy. This result was discussed with the American group (A-group) comparing with A-group's result. 4. J-group tried to perform crystallization of HEW lysozyme in a high magnetic field. And they found that it could control the nucleation rate and orientation of crystals. 5. Appoferritin (A-group) and ferritin (J-group) were highly purified and then crystallized. They showed again that removement of impurities is indispensable for growth of crystals of high quality. J-group made a morphodrom of ferritin. 6. A-group performed light scattering experiments of HEW lysozyme solution and discuss the aggregation process. They estimated the second virial coefficient of the solution and discussed relation between ion intensity and intermolecular interaction. 7. A-group precisely measured topography of vicinal surface with use of the laser interferometry and obtained time evolution of normal and step growth rates and slope of the vicinal surfaces. 8. A-group found that there existed a region where HEW lysozyme solution separated into two liquid phases. They made a phase diagram for this segregation with use of the light scattering technique. 9. In order to estimate the solution layr thickness where convection is ignored, A-grup performed computer simulation of the concentration profiles around a growing crystal changing thickness of the solution layr. J-group measured concentration profiles around a growing lysozyme crystal changing the thickness of the cell. These results were compared each other. 10. J-group measured solubility of HEW lysozyme in situ in high pressure. Pressure dependence of the growth rate was also studied.
• Crystal Growth of Protein

  Date (from‐to) : 1994

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• 2023/08 - Today   International Organization for Crystal Growth   Vice president
• 2016/08 -2020/02   Journal of Crystal Growth   Associate Editor