Research Themes

• Cell dynamics studied by X-ray laser diffraction
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (S)
  29 May 2015 - 31 Mar. 2020
  Nishino Yoshinori
  Through X-ray free electron laser (XFEL) imaging, we obtained results that contribute to basic microbiology, such as the nano-scale dynamics of prokaryotic cell division and the polyploidy of extreme thermophiles. Our XFEL imaging studies are also extended to a wide range of applied research including heat sterilization of dairy products, photothermal treatment of cancer cells using gold nanoparticles, influenza virus, drug delivery, and battery materials for electric vehicles. We also worked on technological development for molecular-level XFEL imaging.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (S), Hokkaido University, 15H05737
• Establishing imaging method for solution structure of complex biomolecular systems utilizing femtosecond coherent X-rays
  Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
  2011 - 2012
  NISHINO Yoshinori, JOTI Yasumasa, BESSHO Yoshitaka, TAKEUCHI Shoji
  We published a review paper describing the basic concept of pulsed coherent x-ray solution scattering (PCXSS) that we are proposing. We developed environmental cells to be used for sample holders which enable measurement in a controlled environment. By numerical simulation, we designed experimental configurations and developed algorithms for data analysis. We performed PCXSS measurement by using an x-ray free-electron laser facility SACLA, and succeeded in recording single-shot coherent x-ray diffraction patterns.
  Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 23651126
• Cryo-bioimaging by using coherent X-ray diffraction
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
  2010 - 2012
  NISHINO Yoshinori, MAESHIMA Kazuhiro
  We revised the established theory of the structure of human chromosomes by X-ray scattering experiments conducted using SPring-8. Experimental data indicate irregularly folded nucleosome fibers without a 30-nm chromatin structure or regularly folding of chromatin fibers. We also proposed a new coherent imaging method using a confined illumination, which can be applicable also to frozen-hydrated biological samples with extended ice layer, to overcome the limitation of conventional data analysis algorithm in X-ray diffraction microscopy.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 22310075
• Nanostructure Analysis of Biospecimens with Coherent X-ray Diffraction Microscopy
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
  2007 - 2009
  NISHINO Yoshinori, MAESHIMA Kazuhiro, TAKAHASHI Yukio
  We performed research in bioimaging with x-ray diffraction microscopy on various aspects concerning microscope hardware development, sample preparation, data acquisition, data analysis, etc. We achieved results including first three-dimensional observation of a cellular organelle using hard x-rays leading research in the field. Our study also provided structural information of biological interest. For example, in the chromosome image which we successfully visualized, axial structure was observed first without staining or other methods to artificially enhance image contrast.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), The Institute of Physical and Chemical Research, 19310084
• In-situ observation of 3 dimensional meso-scopic structures of metallic materials by coherent x-ray diffraction microscopy
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
  2006 - 2008
  MATSUBARA Eiichiro, TAKAHASHI Yukio, NISHINO Yoshinori, OKUDA Hiroshi, KOMURA Yoshiki, ICHITUBO Tetsu
  コヒーレントX線回折顕微鏡(CXDM : Coherent X-ray diffraction microscope)法を用いて、金属材料中のナノ組織観察の方法を確立することが本研究の目的である。軽量・高強度材料として実用上重要なアルミ基、マグネシウム基合金中の微細組織観察を通して、このCXDM法の金属材料に応用する場合の問題を明らかにし、それらを解決して、CXDM法を金属材料中の微細組織観察のための材料評価技術として確立する。CXDM法では、試料から得られるスペックルパターンと呼ばれる鋭い回折強度分布を精密に測定し、反復位相回復法を用いて回折プロファイルから試料の透過像を得る。この際に、位相回復を正確に行うために、オーバーサンプリング条件を満足する必要がある。ただ、現状での検出器の測定領域の大きさと位置分解能による制約から、測定試料の大きさは直径1μm程度に制限されている。この試料の物理的大きさに制限されないタイコグラフ法と呼ばれる手法についても実験的に調べた。
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Kyoto University, 18360304
• X線導波路現象を利用したナノビーム集光素子開発と応用　　　　　　　　　　　　　　　
  科学研究費助成事業 萌芽研究
  2004 - 2005
  松原 英一郎, 林 好一, 西野 吉則, 竹中 久貴
  X線導波路の特徴は、10〜100nmのサイズの干渉性の高いX線を発生することのできる微小X線源や、モノクロメーターのような分光器としての機能を有することである。ここではSi基板上に100nmのPMMAコア層をスピンコーティング法によって、さらにその上にスパッタ法によってSiクラッドを製膜した多層膜をX線導波路とした。計算機シミュレーションでは、効率よくX線を伝搬することのできるX線導波路の構造はエネルギーによって異なることを示しており、そのため、クラッド層の厚みは、0〜20nmの範囲において2nmステップで段階的に変化させた。本実験では、X線管球から放射される特性X線を分光させる目的でSi/PMMA/Siに対し白色X線を入射させ、X線導波路現象の観測を行った。WLβ線を最も効率よく伝搬させるためのクラッド層の厚みは、シミュレーションによって10nmと算出されたため、その試料に対して入射角度を調整し、伝搬X線を観測した。伝搬X線の出射角度依存性を詳細に調べた結果。TE0、1、2、3モードの導波路現象が生じていることが確認された。出射角度0°付近で観測されるTEOモードのエネルギーは9.75keVであり、WLβ線と一致し強度が増強されていることが判明した。MoKα線に対しても同様に分光が行えることも示された。
  また、ペンタセン薄膜においても同様にX線導波路現象を観測した。伝搬X線のエネルギーから導き出される膜の構造(膜厚50m、密度1.35g/cm^3)は他の評価法のものと良い一致を示した。AFMでの形態観測によると、膜厚に対して非常に大きな凹凸が表面に存在していたが、本結果より、滑らかな界面を持つ薄膜だけでなく、粗い界面を持つ薄膜に対してもX線導波路現象が生じることが示された。
  日本学術振興会, 萌芽研究, 16656192
• Understanding of optical luminescence mechanism of phosphors by establishment of X-ray luminescence holography　　　　　　　　　　　　　　　
  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
  2003 - 2005
  MATSUBARA Eiichiro, SHISHIDO Toetsu, HAYASHI Koichi, KISHIMOTO Shunji, NISHINO Yoshinori
  X-ray excited optical luminescence (XEOL) has been applied to the site selective XAFS measurements. On the other hand, atomic resolution x-ray holography, which can determine local structure around a specified atom, normally uses the x-ray fluorescence. Before starting this project, there has been no idea of the use of XEOL for othe X-ray holography. To explore new analytical possibility of the XEOL application, we focused on X-ray incident beam angular anisotropy of the XEOL intensity and studied a feasibility of atomic resolution X-ray holography. A ZnO epitaxial film on Al_2O_3 (sapphire) single crystal was adopted for the sample in the present study, because the XEOL is known to be occurred for ZnO and sapphire. The experiments were done at the synchrotron radiation facility SPring-8. The observed intensity variation of the XEOL corresponded to the hologram pattern of Al_2O_3 substrate, which was different from the X-ray fluorescence hologram pattern of Zn Kα. In order to attribute the XEOL hologram, we estimated positions and amplitudes of the X-rat standing wave lines observed in the hologram patterns by averaging over a given direction of reciprocal lattice space. Measurement of the XEOL spectrum from the ZnO/Al_2O_3 showed that the luminescence from sapphire was dominant, and this was consistent with the result of the XEOL hologram. The X-ray holography measurement using x-ray fluorescence is generally difficult for light elements, such as Al or Si, because of its low cross section for inner shell ionization and the absorption by air. The present study demonstrates that hard x-ray holography measurement for light element can be easily carried out using XEOL. Moreover, we found that the ZnO/AL_2O_3 sample used here emit the strong ultraviolet luminescence (373 nm), which corresponded to bang gap of ZnO thin film, by cooling to 100 K. By selecting the luminescence from ZnO thin film using a grating monochromator, the hologram pattern of ZnO layer could be recorded.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), 15360329