研究者データベース

研究者情報

マスター

アカウント(マスター)

  • 氏名

    惠良田 知樹(エラタ トモキ), エラタ トモキ

所属(マスター)

  • 工学研究院 応用化学部門 生物工学分野

所属(マスター)

  • 工学研究院 応用化学部門 生物工学分野

独自項目

syllabus

  • 2020, 大学院共通授業科目(一般科目):自然科学・応用科学, Inter-Graduate School Classes(General Subject):Natural and Applied Sciences, 修士課程, 大学院共通科目, 生体高分子,水産廃棄物と木質系廃棄物,生分解性高分子,バイオリアクターリサイクル
  • 2020, 生物資源化学特論, Bioresources Chemistry, 修士課程, 総合化学院, 生体高分子,水産廃棄物と木質系廃棄物,生分解性高分子,バイオリアクターリサイクル
  • 2020, 分析化学Ⅱ, Analytical Chemistry Ⅱ, 学士課程, 工学部, 機器分析 スペクトル 有機化学
  • 2020, 化学Ⅰ, Chemistry I, 学士課程, 全学教育, 原子の構造、原子軌道、化学結合、混成軌道、物質の三態、電解質溶液
  • 2020, 物質変換工学, Applied Chemistry and Biochemistry, 学士課程, 工学部, 有機合成,有機材料,化学プロセス,反応器設計,生体材料,高分子材料,分子機能,無機材料,複合材料,電子材料,光機能材料
  • 2020, 応用化学学生実験Ⅲ, Applied Chemistry Laboratory Ⅲ, 学士課程, 工学部, 微生物の培養,微生物の観察,遺伝子工学,形質転換,大量発現,タンパク質精製

researchmap

プロフィール情報

学位

  • 理学博士(筑波大学)

プロフィール情報

  • 惠良田, エラタ
  • 知樹, トモキ
  • ID各種

    201501025598516128

対象リソース

業績リスト

研究キーワード

  • バクテリアセルロース   リグニン   ヨウ素   酢酸菌   セルロース   導電性   電荷移動錯体   ドーピング   CIDNP   菌体サポーター   上下リザーバー   連続抄紙機試作   無終端ベルト   ESR測定   DNAラベリングインデックス   グルコース代謝経路   ラベル化セルロース   動的ヤング率   回転円盤型バイオリアクター   微生物高分子   温度特性   水溶性多糖   面状発熱体   フェノキシラジカル   歯周炎   組織再生   グルコン酸   リアクター   pH   イカ甲キチン   

研究分野

  • ナノテク・材料 / 高分子材料 / セルロース化学
  • ライフサイエンス / 生体材料学
  • ライフサイエンス / 生体医工学
  • ライフサイエンス / 薬系分析、物理化学

経歴

  • 2007年 - 現在 北海道大学 大学院・工学研究科 准教授
  • 1997年 - 2007年 北海道大学 大学院・工学研究科 助教授

受賞

  • 2004年07月 セルロース学会 セルロース学会賞
     固体NMR法を用いた天然セルロースの結晶構造解析 
    受賞者: 惠良田知樹

論文

  • Satoshi Nomura, Yuki Kugo, Tomoki Erata
    Cellulose 27 7 3553 - 3563 2020年05月 [査読有り][通常論文]
  • Satoshi Nomura, Shin-ichiro Sato, Tomoki Erata
    Chemical Physics Letters 742 137154 - 137154 2020年03月 [査読有り][通常論文]
  • Fujita Shin-Ichiro, Segawa Shinji, Kawashima Kazuki, Nie Xuejing, Erata Tomoki, Arai Masahiko
    JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY 34 12 2521 - 2528 2018年12月 [査読有り][通常論文]
  • Markus Bacher, Takashi Hosoya, Nele Sophie Zwirchmayr, Satoshi Nomura, Lars Gille, Thomas Dietz, Tomoki Erata, Antje Potthast, Tapani Vuorinen, Thomas Rosenau
    Cellulose 25 6 3197 - 3203 2018年06月01日 [査読有り][通常論文]
     
    Abstract: 2,5-Dihydroxy-[1,4]-benzoquinone (DHBQ) and 5,8-dihydroxy-[1,4]-naphthoquinone (DHNQ) are two key chromophores which are almost ubiquitous in cellulosic materials. Their fate under conditions of alkaline peroxide bleaching (P stage) has been established previously, but the intermediacy of cyclic peroxides, which so far had only been postulated, remained an open issue. By means of 17O NMR spectroscopy, additionally supported by other NMR techniques, it was demonstrated that both DHBQ and DHNQ form cyclic peroxides as primary intermediates in the reaction with hydrogen peroxide under alkaline conditions. These intermediates are subsequently further degraded to products already known. The experimental confirmation of the cyclic peroxides is an important step in the understanding of reaction mechanisms in pulp bleaching chemistry. Graphical Abstract: [Figure not available: see fulltext.].
  • Tomoki Erata, Hiroyuki Kono
    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 245 2013年04月 [査読有り][通常論文]
  • Y. Satoh, K. Tajima, S. Nakamoto, H. Xuerong, T. Matsushima, T. Ohshima, S. Kawano, T. Erata, T. Dairi, M. Munekata
    JOURNAL OF APPLIED MICROBIOLOGY 111 4 811 - 817 2011年10月 [査読有り][通常論文]
     
    Aims: The aim of this study was to isolate a thermotolerant micro-organism that produces polyhydroxyalkanoates (PHAs) composed of medium-chain-length (mcl) HA units from a biodiesel fuel (BDF) by-product as a carbon source. Methods and Results: We successfully isolated a thermotolerant micro-organism, strain SG4502, capable to accumulate mcl-PHA from a BDF by-product as a carbon source at a cultivation temperature of 45 degrees C. The strain could also produce mcl-PHA from acetate, octanoate and dodecanoate as sole carbon sources at cultivation temperatures up to 55 degrees C. Taxonomic studies and 16S rRNA gene sequence analysis revealed that strain SG4502 was phylogenetically affiliated with species of the genus Pseudomonas. This study is the first report of PHA synthesis by a thermotolerant Pseudomonas. Conclusions: A novel thermotolerant bacterium capable to accumulate mcl-PHA from a BDF by-product was successfully isolated. Significance and Impact of the Study: A major issue regarding industrial production of microbial PHAs is their much higher production cost compared with conventional petrochemical-based plastic materials. Especially significant are the cost of a fermentative substrate and the running cost to maintain a temperature suitable for microbial growth. Thus, strain SG4502, isolated in this study, which assimilates BDF by-product and produces PHA at high temperature, would be very useful for practical application in industry.
  • Tomoki Erata
    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 235 2008年04月 [査読有り][通常論文]
  • Tomoki Erata, Hiroyuki Kono
    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 231 2006年03月 [査読有り][通常論文]
  • A Nakayama, A Kakugo, JP Gong, Y Osada, M Takai, T Erata, S Kawano
    ADVANCED FUNCTIONAL MATERIALS 14 11 1124 - 1128 2004年11月 [査読有り][通常論文]
     
    Double-network (DN) hydrogels with high mechanical strength have been synthesized using the natural polymers bacterial cellulose (BC) and gelatin. As-prepared BC contains 90% water that can easily be squeezed out, with no more recovery in its swelling property. Gelatin gel is brittle and is easily broken into fragments under a modest compression. In contrast, the fracture strength and elastic modulus of a BC-gelatin DN gel under compressive stress are on the order of megapascals, which are several orders of magnitude higher than those of gelatin gel, and almost equivalent to those of articular cartilage. A similar enhancement in the mechanical strength was also observed for the combination of BC with polysaccharides, such as sodium alginate, gellan gum, and i-carrageenan.
  • Y Marubashi, T Higashi, S Hirakawa, S Tani, T Erata, M Takai, J Kawamata
    OPTICAL REVIEW 11 6 385 - 387 2004年11月 [査読有り][通常論文]
     
    The molecular chain orientation of mercerized cellulose II was examined by optical second harmonic generation (SHG) measurements. The SHG intensities of several kinds of mercerized cellulose II were found to be much larger than those expected for a structural model with an antiparallel molecular chain orientation as proposed by X-ray studies. This result suggests that the orientation of mercerized cellulose II is parallel as suggested by molecular dynamics simulation. (C) 2004 The Optical Society of Japan.
  • H Kono, Y Numata, T Erata, M Takai
    MACROMOLECULES 37 14 5310 - 5316 2004年07月 [査読有り][通常論文]
     
    Through-bond C-13-C-13 and C-13-H-1 correlations in the crystal structure of cellulose II were determined by the two-dimensional (2D) refocused INADEQUATE and MAS-J-HMQC spectra of the mercerized cellulose, which was biosynthesized by Acetobacter xylinum ATCC 10245 from the uniformly labeled glucose (D-(U-C-13(6))glucose). Mercerization of the bacterial cellulose was achieved in a solution of 20% NaOH in water for 2 weeks. In the 2D INADEQUATE spectrum of cellulose II, two sets of the through-bond C-13-C-13 connectivities from C1 through C6 were clearly observed, which enabled us to completely assign the complex 1D CP/MAS C-13 spectrum of cellulose II. Following the C-13 assignment, the H-1 resonance for the proton(s) attached to each carbon of cellulose II could be assigned by use of the 2D MAS-J-HMQC spectrum of the mercerized cellulose.
  • K Tajima, Y Satoh, K Nakazawa, H Tannai, T Erata, M Munekata, M Kamachi, RW Lenz
    MACROMOLECULES 37 12 4544 - 4546 2004年06月 [査読有り][通常論文]
     
    We succeeded in developing of a new method for in vitro poly(3-hydroxybutyrate) (P(3HB)) synthesis with coenzyme A (CoA) recycling. Thiophenyl (R)-3-hydroxybutyrate was used as a precursor for the monomer, (R)-3-hydroxybutylCoA ((R)-3HBCoA). The (R)-3HBCoA was synthesized by the ester exchange reaction between thiophenyl (R)-3-hydroxybutyrate and CoA. Although the polymerization reaction in the buffer (water phase) was performed, the reaction did not occurred. The results of a PHA synthase assay in the presence of thiophenol suggested that the reaction was inhibited by a small amount of thiophenol. To avoid the inhibition of PHA synthase by thiophenol, a water-organic solvent two-phase reaction system was developed for the polymerization reaction. The water-organic solvent two-phase reaction system has been used previously for the bioconversion of substrates with low solubility in water; it was used to remove thiophenol released during the ester exchange reaction from the water phase. Thiophenyl (R)-3-hydroxybutyrate and PHA synthase were dissolved in the organic solvent and water phases, respectively. Ester exchange between thiophenol and CoA occurs at the interface of water and the organic solvent phase, and the (R)-3HB 3-hydroxybutylCoA synthesized was polymerized sequentially by PhaC. The organic solvents with high a logP(ow) of more than 3.9 such as hexane, octane, decane, or dodecane were found to be suitable for the organic solvent phase in the two-phase system. The polymerization reaction mixture showed signs of turbidity in 2 h, after which white precipitates formed. The structural analyses by H-1 NMR spectroscopy indicated that the product was P(3HB). The weight-averaged molecular weight and molecular weight distribution of P(3HB) synthesized were found to be 1.6 x 10(6) and 2.9, respectively. The maximum yield of P(3HB) based on thiophenyl (R)-3-hydroxybutyrate was 47%.
  • S Shimokawa, T Yokono, T Mizuno, H Tamura, T Erata, T Araiso
    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS & EXPRESS LETTERS 43 4B L545 - L547 2004年04月 [査読有り][通常論文]
     
    X-ray diffraction measurements were made on water irradiated with far-infrared (FIR) light. It was found that the X-ray diffraction intensity at a 2theta angle of 30degrees increased by about 2 times with the irradiation. The increase in the X-ray diffraction intensity was interpreted in terms of the destruction of water clusters.
  • Y Numata, H Kumagai, H Kono, T Erata, M Takai
    SEN-I GAKKAISHI 60 3 75 - 80 2004年03月 [査読有り][通常論文]
     
    A computer aided molecular design (CAMD) technique was applied to investigate a possible packing model for cellulose triacetate I (CTA I). The model was constructed based on structural data obtained by CP/MAS (13) NMR. The starting model was determined by molecular mechanics (MM) calculations on the basis of a model proposed previously by X-ray diffraction data. Molecular dynamics (MD) calculation data indicated the CTA I crystalline has a one-chain, monoclinic structure with unit cell parameters of a = 1.19 nm, b = 0.65 nm, c (fiber repeat) = 1.08 nm, and gamma = 104degrees; the torsion angles chi (C4-C5-C6-O6) are gauche-gauche (gg); and that the side chains are one kind of conformation, respectively. This structure reveals that a glucopyranose residue becomes an asymmetric unit, whereas the previous model contains two independent chains per unit cell with P2(1). Hence, we propose a refined structure of CTA I.
  • Hiroyuki Kono, Yukari Numata, Tomoki Erata, Mitsuo Takai
    Polymer 45 8 2843 - 2852 2004年 [査読有り][通常論文]
  • Y Numata, H Kono, S Kawano, T Erata, M Takai
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 96 5 461 - 466 2003年11月 [査読有り][通常論文]
     
    Complete assignments of the cross-polarization/magic-angle spinning (CP/MAS) C-13 nuclear magnetic resonance (NMR) spectrum of the cellulose I-ethylenediamine (EDA) complex, which is the intermediate of the reaction from cellulose I to cellulose III1, were performed. In this paper, we used the (13) C-enriched cellulose that was biosynthesized by Acetobacter xylinum ATCC10245 strain from culture medium containing D-(2-C-13), D-(3-C-13), or D-(5-C-13)glucose as a carbon source. After conversion into cellulose I-EDA complex by sufficient EDA treatment, the CP/MAS C-13 NMR spectra of the C-13-enriched cellulose I-EDA complexes were measured. As a result, C-11 resonance lines of each carbon of the cellulose moiety in the complex appeared as a singlet, suggesting that all glucose residues of the complex are magnetically equivalent. The difference in chemical shifts for each carbon between cellulose I-EDA and cellulose I-alpha, I-beta, and IIII, respectively, suggests that the conformation of the cellulose chains for cellulose I-EDA differs from that for cellulose Ialpha, Ibeta, and III1. In addition, fitting analysis of the C-13 spectrum of Valonia cellulose I-EDA complex revealed that the complex contains one EDA molecule per two glucose residues in the cellulose chain.
  • H Kono, T Erata, M Takai
    MACROMOLECULES 36 14 5131 - 5138 2003年07月 [査読有り][通常論文]
     
    wsing the two-dimensional (2D) refocused CP-INADEQUATE spectra of natural abundance Cladophora and tunicate celluloses, we determined the C-13 homonuclear through-bond correlations of cellulose I (alpha) and I-beta, respectively. Two sets of the C-13-C-13 connectivities from C1 through C6 were observed in the 2D INADEQUATE spectrum of the respective cellulose where two directly bonded carbons share the common frequency in the double quantum dimension, which indicated that both cellulose I-alpha and I-beta contain two magnetically nonequivalent anhydroglucose residues in the unit cells. After the C-13 assignment of each carbon of the cellulose I-alpha and i(beta) assignments of the H-1 chemical shifts of protons attached to each carbon of the both allomorphs were performed by use of the 2D MAS-J-HMQC spectra of the cellulose samples for the first time. These spectra gave the through-bond C-13-H-1 correlations, which allowed the assignment of the H-1 chemical shifts of protons that bind to C1, C3, C4, and C6 of the cellulose I-alpha and I-beta. From the differences in the C-13 and H-1 shifts of cellulose L, and It, it was revealed that the primary difference between two forms of cellulose 1 was in the conformations of anhydroglucose residues contained in the cellulose chains. In addition, the conformational difference in the torsion angle around the beta-1,4 linkage between cellulose I-alpha and I-beta was suggested by the notable differences in their H-1 chemical shifts of protons attached to C1.
  • H Kono, T Erata, M Takai
    MACROMOLECULES 36 10 3589 - 3592 2003年05月 [査読有り][通常論文]
     
    For the assignment of C-13 resonance for C2, C3, and C5 of cellulose IIII, C-13-enriched celluloses were biosynthesized by Acetobacter xylinum (A. xylinum) ATCC 10245 in the culture medium containing D-(2-C-13), D-(3-C-13), or D-(5-C-13)glucose. After the C-13-enriched celluloses and Cladophora cellulose were converted into IIII allomorph by the ethylenediamine treatment, cross-polarization/magic angle spinning (CP/MAS) C-13 NMR spectra of these cellulose IIII samples were measured. By comparison of the CP/MAS C-13 NMR spectrum of Cladophora cellulose sample with those of the C-13-enriched celluloses, C-13 resonance lines of the cellulose IIII were completely assigned for the first time. As a result, all carbons of cellulose IIII were shown in singlet in the CP/MAS spectrum of cellulose IIII, which suggests that cellulose IIII is made up of one kind of glucopyranose residue.
  • T Erata
    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 225 U272 - U273 2003年03月 [査読有り][通常論文]
  • J Kawamura, N Kuwata, Y Nakamura, T Erata, T Hattori
    SOLID STATE IONICS 154 183 - 188 2002年12月 [査読有り][通常論文]
     
    A narrow Ag-109 NMR spectrum of superionic conductor glass containing AgI exhibits strong broadening at low temperature or at low concentration of AgI. This broadening of the spectrum is attributed to the inhomogeneity of the local structure around Ag+ ions in the glass. The temperature and composition dependence of the spectra can be well explained by a multisite exchange (MSE) model. The existence of the local inhomogeneity and the exchange of Ag+ ions among them can be detected by site-selective hole-burning NMR technique. In this paper, the first measurement of the NMR hole-burning spectra of a superionic conductor glass of AgI-AgPO3 is reported. A clear hole is observed below -20 degreesC, which diffuses to the higher-frequency region corresponding to AgI-rich sites, where the exchange rate is faster. This technique is very useful to investigate site exchange of ions in disordered systems. (C) 2002 Elsevier Science B.V. All rights reserved.
  • S Kawano, K Tajima, Y Uemori, H Yamashita, T Erata, M Munekata, M Takai
    DNA RESEARCH 9 5 149 - 156 2002年10月 [査読有り][通常論文]
     
    About 14.5 kb of DNA fragments from Acetobacter xylinum. ATCC23769 and ATCC53582 were cloned, and their nucleotide sequences were determined. The sequenced DNA regions contained endo-beta-1,4-glucanase, cellulose complementing protein, cellulose synthase subunit AB, C, D and beta-glucosidase genes. The results from a homology search of deduced amino acid sequences between A. xylinum ATCC23769 and ATCC53582 showed that they were highly similar. However, the amount of cellulose production by ATCC53582 was 5 times larger than that of ATCC23769 during a 7-day incubation. In A. xylinum ATCC53582, synthesis of cellulose continued after glucose was consumed, suggesting that a metabolite of glucose, or a component of the medium other than glucose, may be a substrate of cellulose. Oil the other hand, cell growth of ATCC23769 was twice that of ATCC53582. Glucose is the energy source in A. xylinum as well as the substrate of cellulose synthesis, and the metabolic pathway of glucose in both strains may be different. These results suggest that the synthesis of cellulose and the growth of bacterial cells are contradictory.
  • S Kawano, K Tajima, H Kono, T Erata, M Munekata, M Taka
    JOURNAL OF BIOSCIENCE AND BIOENGINEERING 94 3 275 - 281 2002年09月 [査読有り][通常論文]
     
    Endo-beta-1,4-glucanase (CMCax; EC 3.2.1.4) from Acetobacter xylinum ATCC23769 was expressed as a 6xHis-tagged fusion protein in Escherichia coli. The optimal temperature, pH, K. and V-max of the purified His-tagged CMCax toward carboxymethyl cellulose were 50degreesC, 4.5, 20 mg/ml and 37.2 muM/min, respectively. The number of recognition residues of cello-oligosaccharide by this enzyme were five (cellopentaose) or longer, and the stereochemical course of hydrolysis was of the inverting type. Addition of a small amount (1.5 mg/l) of His-tagged CMCax into a culture medium enhanced cellulose production 1.2-fold. CMCax overproduction in A. xylinum also enhanced the yield of cellulose production. Transmission electron microscopic analysis revealed that the cellulose ribbons secreted from the CMCax overproducing strain were dispersed compared with those from the wild type strain in the same manner as by carboxymethyl cellulose addition. These results could suggest that CMCax from A. xylinum influences in cellulose ribbon assembly, which is considered to be a rate-determined process in cellulose synthesis.
  • H Kono, T Erata, M Takai
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 124 25 7512 - 7518 2002年06月 [査読有り][通常論文]
     
    Complex ring C-13 resonance lines of the cross-polarization/magic angle spinning (CP/MAS) C-13 NMR spectra of cellulose triacetate (CTA) I and CTA II were completely assigned, for the first time, by C-13-enriched CTA allomorphs. The C-13-enriched CTA I was prepared by heterogeneous acetylation of bacterial cellulose which was biosynthesized by Acetobacter xylinum (A. xylinum) ATCC10245 from culture medium containing D-(2-C-13)-, D-(3-C-13)-, or D-(5-C-13)glucose as a carbon source, while CTA II samples were obtained by solution acetylation of the C-13-enriched bacterial celluloses. From comparison of the spectra of normal CTA prepared from ramie with those of the enriched CTA samples, it was revealed that all carbons composed of CTA I appeared as a singlet, while those of CTA II except for Cl were shown as equal-intensity doublets in the CP/MAS C-13 NMR spectrum. This finding suggests that CTA I is made up of one kind of glucopyranose residue while there are two magnetically inequivalent sites in the unit cell of CTA II in the same population.
  • H Kono, S Yunoki, T Shikano, M Fujiwara, T Erata, M Takai
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 124 25 7506 - 7511 2002年06月 [査読有り][通常論文]
     
    The precise assignments of cross polarization/magic angle spinning (CP/MAS) C-13 NMR spectra of cellulose I-alpha and I-beta were performed by using C-13 labeled cellulose biosynthesized by Acetobacter xylinum (A. xylinum) ATCC10245 strain from culture medium containing D-[1,3-C-13]glycerol or D-[2-C-13]glucose as a carbon source. On the CP/MAS C-13 NMR spectrum of cellulose from D-[1,3-C-13] glycerol, the introduced C-13 labeling were observed at C1, C3, C4, and C6 of the biosynthesized cellulose. In the case of cellulose biosynthesized from D-[2-C-13]glucose, the transitions of C-13 labeling to C1, C3, and C5 from C2 were observed. With the quantitative analysis of the C-13 transition ratio and comparing the CP/MAS C-13 NMR spectrum of the Cladophora cellulose with those of the C-13 labeled celluloses, the assignments of the cluster of resonances which belong to C2, C3, and C5 of cellulose, which have not been assigned before, were performed. As a result, all carbons of cellulose I-alpha and I-beta except for C1 and C6 of cellulose I-alpha and C2 of cellulose I-beta were shown in equal intensity of doublet in the CP/MAS spectrum of the native cellulose, which suggests that two inequivalent glucopyranose residues were contained in the unit cells of both cellulose I-alpha and I-beta allomorphs.
  • H Kono, T Erata, M Takai
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 124 25 7512 - 7518 2002年06月 [査読有り][通常論文]
     
    Complex ring C-13 resonance lines of the cross-polarization/magic angle spinning (CP/MAS) C-13 NMR spectra of cellulose triacetate (CTA) I and CTA II were completely assigned, for the first time, by C-13-enriched CTA allomorphs. The C-13-enriched CTA I was prepared by heterogeneous acetylation of bacterial cellulose which was biosynthesized by Acetobacter xylinum (A. xylinum) ATCC10245 from culture medium containing D-(2-C-13)-, D-(3-C-13)-, or D-(5-C-13)glucose as a carbon source, while CTA II samples were obtained by solution acetylation of the C-13-enriched bacterial celluloses. From comparison of the spectra of normal CTA prepared from ramie with those of the enriched CTA samples, it was revealed that all carbons composed of CTA I appeared as a singlet, while those of CTA II except for Cl were shown as equal-intensity doublets in the CP/MAS C-13 NMR spectrum. This finding suggests that CTA I is made up of one kind of glucopyranose residue while there are two magnetically inequivalent sites in the unit cell of CTA II in the same population.
  • M Nishikawa, K Ono, E Kita, H Yanagihara, T Erata, A Tasaki
    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 238 1 91 - 100 2002年01月 [査読有り][通常論文]
     
    Multilayers composed of Fe and MgF2 with layer thicknesses between 9 Angstrom and 100 Angstrom and of 30 Angstrom, respectively, were prepared with an ultrahigh-vacuum deposition technique. Medium-angle X-ray data show that the Fe layers in the BCC phase have considerable (I 10) texture. Periodicity due to multilayered structures was confirmed by a small-angle X-ray diffraction study and cross-section transmission electron microscope for films with Fe layer thicknesses > 45 Angstrom. In an Fe/MgF2(9 Angstrom/30 Angstrom) sample, an island structure for the Fe layers was suggested by the existence of superparamagnetism in a film. At 4.2K, enhancements of both magnetization and hyperfine field were observed in films having Fe layers thinner than 40 A. The maxima in the magnetization (233 emu/g of Fe) and in the average hyperfine field (390 kOe) at 4.2K were found in an Fe/MgF2(9Angstrom/30Angstrom) film and were approximately 105% and 115% that of the bulk alpha-Fe, respectively. The thickness dependence suggests a 12% enhancement in the magnetic moment of interface Fe atoms. No exchange bias was found in the films, implying that antiferromagnetic fluorides are not formed at the interface, which is different from the case of Fe/LiF and Fe/CaF2 multilayers. (C) 2002 Elsevier Science B.V. All rights reserved.
  • K Furuya, K Ogawa, Y Mineo, A Matsufuji, J Okuda, T Erata
    JOURNAL OF PHYSICS-CONDENSED MATTER 13 14 3519 - 3532 2001年04月 [査読有り][通常論文]
     
    The lithium insertion reactions with tin (II) oxide (SnO) and tin-based composite oxide (abbreviated as TBCO) are studied by solid Li-7-NMR Knight shift, T-1 and T-1 rho, relaxation rate, TEM and tn situ XRD methods. By the insertion reaction for SnO, the lithium oxide and beta -tin are produced first at Li/Sn = 2; at Li/Sn = 3 to 6 the products are not simple and a mixture of LiSn2, LiSn, Li5Sn2 and Li7Sn2 alloys is detected during the insertion. For the TBCO, which is revealed as amorphous, mainly constituted by randomly distributed very short-range (order of 10(-9) In) regions by TEM observation, it is found that elsctrochemically inserted lithium forms Li2O and produces metallic tin (Sn) in the first step (Li/Sn < 2), then the highly ionic lithium-tin alloys, Li7Sn2 land Li7Si2), are produced in the second step (Li/Sn > 2). During the second step, the Li/Sn ratio of formed lithium-tin alloy is kept at almost 4. By the analyses of Li-7 NMR Knight shifts, line shape and lit situ XRD, the lithium-inserted TBCOs are characterized as almost amorphous and mixtures of highly ionic components.
  • T Seino, A Yoshioka, M Fujiwara, KL Chen, T Erata, M Tabata, M Takai
    WOOD SCIENCE AND TECHNOLOGY 35 1-2 97 - 106 2001年04月 [査読有り][通常論文]
     
    An electron spin resonance (ESR) method combined with a spin trapping reagent was successfully applied to trap and characterize unstable radicals which were generated by ultrasonic irradiation of dimethylsulfoxide (DMSO) solution of hardwood, Fagus crenata lignin. It was found, consequently, that a secondary carbon radical, similar to CH . was trapped as the nitroxide spin adduct when the DMSO solution was subjected to ultrasonic irradiation in the presence of a spin trapping reagent: 2, 4, 6-tri-tert-butylnitrosobenzene (BNB) at 50 degreesC for 60 minutes under vacuum. This means that the alkyl phenyl ether bonds known as lignin linkage bonds were homolytically scissoned by the ultrasonic irradiation, although the phenoxy radical, Ph-O . as the counter radical of the secondary carbon radical was not trapped by the BNB spin trap. Further, the data showed that the primary carbon radical, similar to OCH2. is trapped by the BNB to form the corresponding spin adduct, indicating that the hydrogen abstraction from the ortho methoxy group in the syringyl and/or guaiacyl moiety is induced by the secondary carbon radical when irradiated. Based on these findings it was concluded that the Ph-O . radicals produced by the homolytic rupture of the alkyl phenyl ether bonds were not trapped by the BNB spin trap. This suggests that large steric hindrances operate between the syringyl with two methoxy moieties and/or guaiacyl with a methoxy moiety at the ortho position, and the BNB molecule bearing two bulky ortho tert-butyl groups.
  • Hiroyuki Kono, Markus R. Walchli, Masashi Fujiwara, Tomoki Erata, Mitsuo Takai
    Recent Advance in Environmentally Compatible Polymers, J. F. Kennedy, G. O. Phillips, and P. A. Williams (Eds.), Woodhead Publishing Limited, Cambridge 365 - 370 2001年03月 [査読有り][通常論文]
  • Masashi Fujiwara, Yoshiko Osada, Shunji Yunoki, Hiroyuki Kono, Tomoki Erata, Mitsuo Takai
    Recent Advance in Environmentally Compatible Polymers, J. F. Kennedy, G. O. Phillips, and P. A. Williams (Eds.), Woodhead Publishing Limited, Cambridge 359 - 364 2001年03月 [査読有り][通常論文]
  • Hiroyuki Kono, Yukari Numata, Nobuhiro Nagai, Masashi Fujiwara, Tomoki Erata, Mitsuo Takai
    Recent Advance in Environmentally Compatible Polymers, J. F. Kennedy, G. O. Phillips, and P. A. Williams (Eds.), Woodhead Publishing Limited, Cambridge 269 - 274 2001年03月 [査読有り][通常論文]
  • H Konno, T Erata, K Fujita, Y Aoki, K Shiba, N Inoue
    CARBON 39 5 779 - 782 2001年 [査読有り][通常論文]
  • K Tajima, T Tanio, Y Kobayashi, H Kohno, M Fujiwara, T Shiba, T Erata, M Munekata, M Takai
    DNA RESEARCH 7 4 237 - 242 2000年08月 [査読有り][通常論文]
     
    The levansucrase gene (lsxA) was cloned from the genomic DNA of Acetobacter xylinum NCI 1005, and the nucleotide sequence of the lsxA gene (1,293 bp) was determined. The deduced amino acid sequence of the lsxA gene showed 57.4% and 46.2% identity with the levansucrases from Zymomonas mobilis and Erwinia amylovora, respectively, while only 35.2% identity with that from Acetobacter diazotrophicus. The gene product of lsxA (LsxA) that was overproduced in E. coli coded for a polypeptide of molecular mass 47 kDa. The LsxA released glucose and produced polysaccharide from sucrose, the structure of which was analyzed by nuclear magnetic resonance spectroscopy and determined to be a beta-(2,6)-linked polyfructan. From these results, it can be concluded that the lsxA gene encodes A. xylinum levansucrase.
  • T Akasaka, Y Maeda, T Wakahara, T Mizushima, W Ando, M Walchli, T Suzuki, K Kobayashi, S Nagase, M Kako, Y Nakadaira, M Fujitsuka, O Ito, Y Sasaki, K Yamamoto, T Erata
    ORGANIC LETTERS 2 17 2671 - 2674 2000年08月 [査読有り][通常論文]
     
    [GRAPHICS] In the photochemical bis-germylation of C-60 with 1,1,2,2-tetrakis(2,6 diethylphenyl)-1,2-digermirane (1), a cycloadduct (2) is obtained in high yield for the first time. Spectroscopic analysis and theoretical investigation confirm that 2 (which has C-1 symmetry) results from 1,4-cycloaddition. Control experiments and laser flash photolysis experiments suggest that an exciplex intermediate is responsible for the formation of 2. The redox properties of 2 were examined by differential pulse voltammetry.
  • H Kono, S Kawano, T Erata, M Takai
    JOURNAL OF CARBOHYDRATE CHEMISTRY 19 2 127 - 140 2000年 [査読有り][通常論文]
     
    A new beta-glucosidase, which was partially purified from Trichoderma viride cellulase, catalyzed a transglycosylation reaction of cellobiose to give beta-D-Glcp-(1-->6)beta-D-Glcp-(1 --> 4)-D-Glcp 1 and beta-D-Glcp-(1 --> 6)-beta-D-Glcp-(1 --> 6)-beta-D-Glcp-(1 --> 4)-D-Glcp 2, regioselectively. Furthermore, the enzyme converted laminaribiose and gentiobiose into beta-D-Glcp-(1 -->6)-beta-D-Glcp-(1 --> 3)-D-Glcp 3 and beta-o-Glcp-(1 --> 6)-beta-D-Glcp-(1 --> 6)-D-Glcp 4, respectively. Selective beta-(1-->6) transglycosylation was achieved.
  • H Kono, Y Numata, N Nagai, T Erata, M Takai
    CARBOHYDRATE RESEARCH 322 3-4 256 - 263 1999年12月 [査読有り][通常論文]
     
    The series of crystalline oligomers from alpha-cellobiose octaacetate through alpha-cellohexaose eicosaacetate, listed as below, was prepared from homogeneous acetylation of the corresponding cellooligosaccharides and characterized by C-13 CP/MAS NMR spectroscopy and X-ray analysis in order to obtain the structural models of cellulose triacetate (CTA) in solid state. Progressing toward the hexamer, the NMR spectral feature of the oligomers, in comparison with two allomorphs of CTA I and CTA II, gradually approached that of CTA I. Specifically, chemical shifts of both the hexamer and the pentamer were in considerable respective agreement with those of CTA I. In addition, X-ray diffraction patterns of the oligomers established that the crystalline pentamer and hexamer have a CTA I lattice in spite of recrystallization from ethylacetate-hexane. We therefore concluded that the pentamer and hexamer would be useful models for the CTA I structure. (C) 1999 Elsevier Science Ltd. All rights reserved.
  • H Kono, Y Numata, N Nagai, T Erata, M Takai
    JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY 37 22 4100 - 4107 1999年11月 [査読有り][通常論文]
     
    A series of crystalline oligomers from alpha-D-cellobiose octaacetate through alpha-D-cellohexaose eicosaacetate were prepared by homogeneous acetylation of the corresponding cellooligosaccharides and characterized by cross-polarization and magic angle sample spinning (CPMAS) carbon-13 nuclear magnetic resonance (C-13 NMR) spectroscopy and X-ray analysis to obtain the structural models of cellulose triacetate (CTA) in the solid state. Progressing toward the hexamer, the NMR spectral features of the oligomers, in comparison with two allomorphs of CTA I and CTA II, gradually approached those of CTA I. Specifically, chemical shifts of both the hexamer and pentamer were in agreement with those of CTA I. In addition, X-ray diffraction patterns of the oligomers established that the crystalline pentamer and hexamer had a CTA I lattice despite recrystallization from ethylacetate-n-hexane. Therefore, we conclude that the pentamer and hexamer are useful models for the CTA I structure. (C) 1999 John Wiley & Sons, Inc.
  • H Kono, MR Waelchili, M Fujiwara, T Erata, M Takai
    CARBOHYDRATE RESEARCH 321 1-2 67 - 74 1999年09月 [査読有り][通常論文]
     
    A new beta-glucosidase was partially purified from Trichoderma viride cellulase complex. This beta-glucosidase hydrolyzed beta-(1-->2)-, beta-(1-->3)-, beta-(1-->4)-, and beta-(1-->6)-linked glucobioses and catalyzed a transglycosylation reaction of cellobiose to give regioselectively beta-D-Glc-(1-->6)-beta-D-Glc-(1-->4)-D-Glc (yield: 18.8%) and beta-D-Glc-(1-->6)-beta-D-Glc-(1-->6)-beta-D-Glc-(1-->4)-D-Glc (3.7%). Furthermore, the enzyme converted laminarabiose and gentiobiose into beta-D-Glc-(1-->6)-beta-D-Glc-(1-->3)-D-Glc (15.3%) and beta-D-Glc-(1-->6)-beta-D-Glc-(1-->6)-D-Glc (20.2%), respectively. The structures of the products were determined by H-1 and C-13 NMR spectroscopy. This high regio- and stereoselectivity demonstrated by the enzyme could be applied for oligosaccharide synthesis in general. (C) 1999 Elsevier Science Ltd. All rights reserved.
  • H Kono, S Kawano, K Tajima, T Erata, M Takai
    GLYCOCONJUGATE JOURNAL 16 8 415 - 423 1999年08月 [査読有り][通常論文]
     
    A new beta-glucosidase was partially purified from Trichoderma viride cellulase. This beta-glucosidase catalyzed a transglycosylation reaction of cellobiose to give beta-D-Glc-(1 --> 6)-beta-D-Glc-(1 --> 4)-D-Glc (1, yield: 18.8%) and beta-D-Glc-(1 --> 6)-beta-D-Glc-(1 --> 6)-beta-D-Glc-(1 --> 4)-D-Glc (2, 3.7%), regioselectively. Furthermore, the enzyme regioselectively converted laminaribiose and gentiobiose into beta-D-Glc-(1 --> 6)-beta-D-Glc-(1 --> 3)-D-Glc (3, 15.3%) and beta-D-Glc-(1 --> 6)-beta-D-Glc-(1 --> 6)-D-Glc (4, 20.2%), respectively. The structures (1-4) of the products were determined by H-1 and C-13 NMR spectroscopies. This high regio- and stereoselectively of the beta-glucosidase could be applied for oligosaccharide synthesis. [GRAPHICS]
  • H Kono, MR Waelchli, M Fujiwara, T Erata, M Takai
    CARBOHYDRATE RESEARCH 319 1-4 29 - 37 1999年06月 [査読有り][通常論文]
     
    A commercial cellulase from Trichoderma viride was fractionated into three fractions, F1, F2, and F3, in order to investigate transglycosylation activities. Among these fi actions, F3, which demonstrated highly hydrolytic activity toward p-nitrophenyl P-D-glucopyranoside and Avicel, most effectively catalyzed the transglycosylation of cellobiose and converted cellobiose into beta-Glc-(1 --> 6)-beta-glc-(1 --> 4)-Glc and beta-Glc-(1 --> 6)-beta-Glc-(1 --> 6)-beta-Glc-(1 --> 4)-Glc. The F3 fraction contained the enzyme to catalyze beta-glucosyl transfer toward only the C-6 position of the sugar acceptor, and thus it is expected to be of use for syntheses of functional oligosaccharides. (C) 1999 Elsevier Science Ltd. All rights reserved.
  • H Yamada, J Takeuchi, H Nakamura, Y Seo, A Tasaki, T Erata
    JOURNAL OF MAGNETIC RESONANCE 135 1 99 - 103 1998年11月 [査読有り][通常論文]
     
    This is a trial to simplize sequences to get the relaxation function f(31)(t), which is usually detected by the double- or triple-quantum filtered (DQF or TQF) NMR in an isotropic phase, The results indicate that only two phase cycling is needed to get the f(31)(t) function, which shows the advantage of SIN (signal-to-noise ratio) in a minimum acquisition time. The filtering of coherence levels in the creation time need not be limited to double- or triple-quantum coherences. An Rb-87 signal from a 4% (w/w) agar powder in 500-mM RbCl solution is recorded at 130.9 MHz as a Larmor frequency using a Bruker MSL 400 spectrometer. (C) 1998 Academic Press.
  • K Tajima, N Uenishi, M Fujiwara, T Erata, M Munekata, M Takai
    CARBOHYDRATE RESEARCH 305 1 117 - 122 1997年12月 [査読有り][通常論文]
     
    A new water-soluble polysaccharide (WSP) was isolated from a culture of Acetobacter xylinum NCI 1005 grown on sucrose. The structure of the WSP was analysed by nuclear magnetic resonance spectroscopy and determined to be a beta-(2-->6)-linked polyfructan, which is structurally different from the polymer synthesized from glucose instead of sucrose by the same strain. The discovery of this new polysaccharide has revealed that the bacterium is able to synthesize two different kinds of water-soluble polysaccharides. (C) 1998 Elsevier Science Ltd.
  • T Akasaka, S Nagase, K Kobayashi, M Walchli, K Yamamoto, H Funasaka, M Kako, T Hoshino, T Erata
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION IN ENGLISH 36 15 1643 - 1645 1997年08月 [査読有り][通常論文]
  • T Akasaka, S Nagase, K Kobayashi, M Walchli, K Yamamoto, H Funasaka, M Kako, T Hoshino, T Erata
    ANGEWANDTE CHEMIE-INTERNATIONAL EDITION IN ENGLISH 36 15 1643 - 1645 1997年08月 [査読有り][通常論文]
  • K Tajima, N Uenishi, M Fujiwara, T Erata, M Munekata, M Takai
    MACROMOLECULAR SYMPOSIA 120 19 - 28 1997年07月 [査読有り][通常論文]
     
    A new polysaccharide was isolated from the culture of Acetobacter aceti subsp. xylinum (A. xylinum) NCl 1005 grown on sucrose. The structure of the polymer was analyzed by nuclear magnetic resonance (NMR) spectroscopy, The water-soluble polysaccharide (WSP) was determined to be beta(2, 6) linked polyfructan, which was structurally different from the polymer synthesized from glucose instead of sucrose by the same strain. The discovery of the new polysaccharide has elucidated that the bacterium has the ability to synthesize two different kinds of water-soluble polysaccharides.
  • J Takeuchi, H Nakamura, H Yamada, E Kita, A Tasaki, T Erata
    SOLID STATE NUCLEAR MAGNETIC RESONANCE 8 2 123 - 128 1997年04月 [査読有り][通常論文]
     
    Lattice defects in a compound semiconductor, gallium-arsenide are evaluated by two-dimensional nutation nuclear magnetic resonance. Especially in the case of indium doped gallium-arsenide, analysis of the nutation patterns indicates that the electric field gradient exists in the whole crystal. Asymmetry parameters and quadrupolar coupling constants are determined as approximately 1.0 and 93 kHz, respectively. These results suggest that the whole crystal is under slight strain. Through this work, it is demonstrated that a two-dimensional nutation nuclear magnetic resonance is the useful method to investigate the lattice defects in gallium-arsenide. (C) 1997 Elsevier Science B.V.
  • T ERATA, T SHIKANO, Y SHIMIZU, M TAKAI, J HAYASHI
    MACROMOLECULAR SYMPOSIA 99 25 - 29 1995年09月 [査読有り][通常論文]
     
    Two-dimensional C-H correlation NMR spectra are presented for the native cellulose types I alpha and I beta from Cladophora sp. A remarkable difference of correlation peaks between I alpha and I beta was observed, which indicates an essential structure difference between the two types of native cellulose.
  • Y MASUTOMI, N FURUKAWA, T ERATA
    HETEROATOM CHEMISTRY 6 1 19 - 27 1995年01月 [査読有り][通常論文]
     
    Pentafluorophenyl phenyl telluride (1) and 3,5-dichloro-2,4,6-trifluorophenyl phenyl telluride (2) react with pentafluorophenyllithium or 3,5-dichloro-2,4,6-trifluorophenyllithium in THF at low temperatures to form the corresponding tellurium ate complexes (A) and (B) as sole intermediates in the ligand exchange on the hypervalent tellurium atom. The corresponding selenides (3) and (4) also react with identical aryllithium reagents in THF to form the discrete intermediates, selenium ate complexes (C) and (D), in the exchange reactions. In these ligand exchange reactions of tellurides and selenides, electron-withdraw ing ligands occupy the apical positions and the exchange lakes place between these apical-oriented groups. The low-temperature H-1, C-13, Se-77, and Te-125 NMR spectroscopic techniques are effective methods for detection of unstable tellurium and selenium ate complexes.
  • T KUSUKAWA, Y KABE, T ERATA, B NESTLER, W ANDO
    ORGANOMETALLICS 13 11 4186 - 4188 1994年11月 [査読有り][通常論文]
     
    The photochemical reaction of bis(alkylidene)disilacyclobutanes 1a,b with C-60 afforded the stable 1:1 adducts 3a,b, resulting from an unexpected rearrangement of the disilacyclobutane unit. The structures of 3a,b were determined by spectroscopic methods, including Si-29-H-1 HMBC hetero nuclear shift correlation experiments.
  • W ANDO, T KADOWAKI, A WATANABE, N CHOI, Y KABE, T ERATA, M ISHII
    NIPPON KAGAKU KAISHI 3 214 - 223 1994年03月 [査読有り][通常論文]
     
    A series of chalcogen cage compounds are derived from removal of chalcogen of adamantane (II a) and double-decker (IIb) sesquichalcogenide. These chalcogenide are termed nor-adamantane (VIIIa), bisnor-adamantane (VIIb), nor-doubledecker (VIIIb) and bisnor-doubledecker (IXb), respectively. After trichloromonogermane ([1a] and [1b]), trichloromonosilane ([8a] and [8b]), trichloromonostannane ([10a] and [10b]) were subjected to sulfation reaction using H2S/pyridine, Li2S, Na2S, (NH4)2S5, and (Me3Si)2S, only trichloromonogermane ([1a] and [1b]) produced tetrakis(t-butylgermane)pentasulfide as minor products, which has Ge-Ge bonds. As major products, adamantane sesquisulfides ([9a],[9b],[11a], and [11b]), were formed from trichloromonosilane, trichloromonostannane as well as trichloromonogermane. On the contrary, the sulfation and selenation of tetrachlorodisilane [12] and tetrachlorodigermane [15] disclosed with efficient formation of tetrakis[t-butylsilane (germane)] pentasulfide and pentaselenide ([13a],[13b], and [5a]). The X-ray analysis of [13a], and [13b] established nor-adamantane structures, which are formed from Si-Si bonds cleavage. Interestingly, tetrachlorodigermane also produced tetrakis(t-butylgermane)tetrasulfide ([16]), which is derived without Ge-Ge bond cleavage. X-ray analysis confirmed bisnor-adamantane structure for [16].
  • M HATTORI, Y ONODA, T ERATA, ME SMITH, M HATTORI, H OHKI, R IKEDA
    ZEITSCHRIFT FUR NATURFORSCHUNG SECTION A-A JOURNAL OF PHYSICAL SCIENCES 49 1-2 291 - 296 1994年01月 [査読有り][通常論文]
     
    Temperature dependences of Cl-35 and H-2 quadrupole coupling constants and Cl-35 NMR spin-lattice relaxation times in polycrystalline samples were measured in the rotator phase of the butylammonium chlorides C4H9NH3Cl and C4H9ND3Cl, obtainable above the phase transition temperature of 241 K. A rapid decrease of the quadrupole coupling constants of both nuclei upon heating is attributed to increasing dynamic disorder formed around the polar head. The presence of self-diffussion of Cl- ions was revealed from the spin-spin relaxation time and resonance line-width in single crystals, and confirmed by measuring the dc electrical conductivity.
  • M KENMOTSU, H HONDA, H OHKI, R IKEDA, T ERATA, A TASAKI, Y FURUKAWA
    ZEITSCHRIFT FUR NATURFORSCHUNG SECTION A-A JOURNAL OF PHYSICAL SCIENCES 49 1-2 247 - 252 1994年01月 [査読有り][通常論文]
     
    The spin-lattice relaxation time of K-39 NMR observed in the low-temperature phase (T < 264.1 K) of KNO2 is explained by the quadrupole mechanism contributed from a newly found NO2- motion. The in-plane C3 reorientation and the overvall NO2- rotation as well as the self-diffusion were shown in the intermediate phase (T less-than-or-equal-to 314.7 K) and the high-temperature plastic phase (T < melting point: 710 K), respectively, by observing K-39 and N-15 NMR relaxation times and N-15 lineshapes.
  • Masakazu Nishikawa, Eiji Kita, Tomoki Erata, Akira Tasaki
    Journal of Applied Ohysics 73 10 6350 - 6352 1993年10月 [査読有り][通常論文]
  • H OHKI, K HARAZONO, T ERATA, A TASAKI, R IKEDA
    ZEITSCHRIFT FUR NATURFORSCHUNG SECTION A-A JOURNAL OF PHYSICAL SCIENCES 48 10 1005 - 1008 1993年10月 [査読有り][通常論文]
     
    Applying Cu-63 NMR technique, we observed exchange between the nonequivalent copper sites in crystalline Cu6PS5Br, known as a member of the mineral ''argyrodite''. Below 200 K, where the motion of the copper(I) ion is slow, we could distinguish several nonequivalent copper sites. On increasing the temperature, the chemical exchange between the nonequivalent cation sites was seen oo the Cu-63 NMR spectra. We could determine the activation energy for this motion to be 35 kJ mol(-1), in good agreement with the published ionic conductivity.
  • H FUJIHARA, H MIMA, T ERATA, N FURUKAWA
    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY 115 21 9826 - 9827 1993年10月 [査読有り][通常論文]
  • M NISHIKAWA, E KITA, T ERATA, A TASAKI
    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 126 1-3 303 - 306 1993年09月 [査読有り][通常論文]
     
    Multilayered thin films composed of Co (thickness 15-75 angstrom) and MgO (fixed 30 angstrom) showed enhanced magnetization. In particular, the maximum value of magnetization was about 180 emu/g in T(Co) = 23 angstrom at 4.2 K. The increase in magnetization was about 10% of the value of bulk Co (fcc 165 emu/g, hcp 162 emu/g).
  • M NISHIKAWA, E KITA, T ERATA, A TASAKI
    JOURNAL OF APPLIED PHYSICS 73 10 6350 - 6352 1993年05月 [査読有り][通常論文]
     
    Multilayered thin films composed of Co and MgO layers were fabricated with an ultrahigh vacuum deposition technique. Magnetization measurements suggest that antiferromagnetic Co oxides do not form at the interface with the MgO layers. An enhancement of the magnetization is observed in a film with the Co layer thickness thinner than 30 angstrom. The maximum enhancement is about 10% of the bulk magnetization of hcp Co metal in a Co/MgO(22/30 angstrom) multilayered thin film whose magnetization is 180 emu per gram of Co.
  • H FUJIHARA, T UEHARA, T ERATA, N FURUKAWA
    CHEMISTRY LETTERS 22 2 263 - 266 1993年02月 [査読有り][通常論文]
     
    The reaction of 5H,7H-dibenzo[b,g][1,5]ditellurocin with I2 resulted in the formation of the diiodo-ditellurane as a new class of bis-hypervalent chalcogenide. Treatment of the dibromo-derivative of 5H,7H-dibenzo[b,g][1,5]telluraselenocin with aqueous NaOH solution afforded exclusively the telluroxide which showed the strong transannular hypervalent interaction between the tellurinyl group and the selenyl group as evidenced by Se-77 and Te-125 NMR spectroscopy.
  • S OGAWA, Y MASUTOMI, T ERATA, N FURUKAWA
    CHEMISTRY LETTERS 21 12 2471 - 2474 1992年12月 [査読有り][通常論文]
     
    Pentafluorophenyl phenyl telluride and 3,5-dichloro-2,4,6-trifluorophenyl phenyl telluride reacted with pentafluorophenyllithium or 3,5-dichloro-2,4,6-trifluorophenyl-lithium at low temperature to form the corresponding tellurium ate complexes as sole intermediates of the ligand exchange on the hypervalent tellurium centers. In these tellurium ate complexes electron-withdrawing aryl ligands were arranged at apical positions and the ligand exchanges took place between the apical-directing groups.
  • E KITA, M OCHI, T ERATA, A TASAKI
    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 117 1-2 294 - 300 1992年11月 [査読有り][通常論文]
     
    Multilayered thin films of Fe and fluorides (CaF2, LiF) were produced by an ultra-high vacuum electron beam evaporation. Mossbauer studies show that Fe and the fluorides are mixed at their interface and form imperfect compounds implying Fe3+ ions. The presence of exchange anisotropy was confirmed in both Fe/CaF2 and Fe/LiF multilayered thin films, suggesting that magnetic coupling between ferromagnetic and antiferromagnetic parts exists in the film. It was found that the mixing between Fe and LiF occurred mainly at the "tail" interface.
  • Hisashi Fujihara, Yutaka Takaguchi, Takeshi Ninoi, Tomoki Erata, Naomichi Furukawa
    Journal of the Chemical Society, Perkin Transactions 1 20 2583 - 2584 1992年10月 [査読有り][通常論文]
     
    1,5-Ditelluracyclooctane 1 reacted with halogens (I2 and Cl2) to give new dihalogenoditelluranes with a Te(IV)-Te(IV). Reduction of the latter with aqueous NaOH, PhSH, Na2S and SMl2 gave the neutral bis-telluride 1.
  • Satoru TUZI, Kyoko, SHINZAWA‐ITOH, Tomoki ERATA, Akira NAITO, Shinya YOSHIKAWA, Hazime SAITÔ
    The FEBS Journal 208 3 713 - 720 1992年09月 [査読有り][通常論文]
     
    We have recorded 100.6-MHz high-resolution solid-state C-13-NMR spectra of crystalline cytochrome-c oxidase from bovine heart muscle and hen egg-white lysozyme, to compare conformation and dynamics of a typical membrane-protein complex with those of lysozyme. The absence of severe interference with the solid-state C-13-NMR spectra, from both the line broadenings from paramagnetic centers and overlapping of intense detergent signals, provided spectral resolution of C-13-NMR feature of cytochrome-c oxidase crystals comparable to that of lysozyme crystal and better than that of dissolved or lyophilized samples. In fact, the observed peak intensities of the polar heads of the detergents BL8SY and Brij 35 were only about 10% and 3% of the anticipated values, respectively. The dynamic behavior of the backbone and side chains of cytochrome-c oxidase was compared with that of lysozyme on the basis of the C-13 spin-lattice relaxation times (T1): the backbone of the cytochrome-c oxidase turned out to be more flexible than that of lysozyme. Molecular motions of the detergent molecules attached to the proteins are found to be highly heterogeneous. Detergent molecules undergo rapid tumbling motions in the crystals in about 10 ns as detected by T1. In addition to rapid motions, slow motions were detected by H-1 spin-lattice relaxation time in the rotating frame (T1rho(H)) and cross-polarization time (T(CH)), together with data from static spectra, indicating that the aliphatic portion of the detergent interacts more strongly with hydrophobic protein surfaces than do the polar heads.
  • S OGAWA, Y MASUTOMI, N FURUKAWA, T ERATA
    HETEROATOM CHEMISTRY 3 4 423 - 429 1992年08月 [査読有り][通常論文]
     
    Diaryl tellurides undergo rapid ligand exchange and disproportionation reactions on treatment with phenyllithium at -78-degrees-C. Triaryltelluranes [10-Te-3(C3)]- Li+ were identified as discrete intermediates during the reactions by Te-125, H-1, C-13, and CH-COSY NMR studies.
  • Hisashi Fujihara, Hisatomo Mima, Tomoki Erata, Naomichi Furukawa
    Journal of American Chemical Society 114 8 3117 - 3118 1992年04月 [査読有り][通常論文]
  • Satoshi Ogawa, Soichi Sato, Tomoki Erata, Naomichi Furukawa
    Tetrahedron Letters 33 14 1915 - 1918 1992年03月 [査読有り][通常論文]
     
    Solution-state structures of bis(2,2'-biphenylylene)selenurane (1) and tellurane (2) were studied by H-1 and C-13 NMR at low temperature. The first examples of the activation parameters for intramolecular ligand exchange (pseudorotation) of these pentacoordinated group 16 elements bound to four carbon ligands were presented by DNMR experiments.
  • T ERATA, K MISHIMA, E KITA, A TASAKI
    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 104 1589 - 1590 1992年02月 [査読有り][通常論文]
     
    The NMR studies were carried out on the ultra fine particles of vanadium. The observed signal with Knight shift 0.7% might arise form surface region since its intensity increases relatively with decrease of the particle size. The spin-lattice relaxation time of this line maintains the Korringa's relation, which indicates that the surface electrons have still metallic character. This low field shift suggests that the existence of a narrow band and rather localized character of the surface electrons.
  • M OCHI, E KITA, N SAEGUSA, T ERATA, A TASAKI
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 61 1 35 - 38 1992年01月 [査読有り][通常論文]
     
    Multilayered thin films of iron and lithium fluoride (LiF) were prepared using ultrahigh-vacuum deposition with two independently controlled E-guns as heat sources. Mossbauer spectra corresponding to metallic Fe atoms and Fe3+ ions were observed in these films. The magnetization curve at 4.2 K was shifted with a magnetic field cooling from room temperature where absolute values of Hc's for + magnetic field and - magnetic field were different. This suggests that exchange anisotropy due to magnetic exchange coupling between ferromagnetic and antiferromagnetic parts exists in the film.
  • H FUJIHARA, Y TAKAGUCHI, JJ CHIU, T ERATA, N FURUKAWA
    CHEMISTRY LETTERS 21 1 151 - 154 1992年01月 [査読有り][通常論文]
     
    A new heterocycle containing tellurium and sulfur atoms, 5H,7H-dibenzo-[b,g][1,5]tellurathiocin (1), has been synthesized. The transannular bond formation between tellurium and sulfur atoms was found in the reaction of 1 with concd H2SO4 by H-1, C-13, and Te-125 NMR spectroscopy. Two-electron oxidation of 1 with 2 equiv. of NOPF6 gave the tellurathia dication salt 3 (> Te+-S+ < 2PF6-) which acts as an oxidizing agent.
  • Hitoaki Yoshida, Yoichi Takahara, Tomoki Erata, Wataru Ando
    Journal of the American Chemical Society 114 3 1098 - 1100 1992年01月01日 [査読有り][通常論文]
  • S OGAWA, Y MATSUNAGA, S SATO, T ERATA, N FURUKAWA
    TETRAHEDRON LETTERS 33 1 93 - 96 1992年01月 [査読有り][通常論文]
     
    Direct evidence for the formation of tetraphenyl sulfurane was presented in the reactions of triphenylsulfonium hexafluorophosphate and diphenyl sulfoxide with phenyllithium by H-1, C-13, and CH-COSY NMR studies at low temperature.
  • H FUJIHARA, T NINOI, R AKAISHI, T ERATA, N FURUKAWA
    TETRAHEDRON LETTERS 32 35 4537 - 4540 1991年08月 [査読有り][通常論文]
     
    A new cyclic bis-telluride, 1,5-ditelluracyclooctane (1), has been synthesized. Two-electron oxidation of 1 with two equivalents of NOBF4 or NOPF6 afforded a novel ditelluride dication BF4- or PF6- salt 2 which was characterized by Te-125 NMR spectroscopy, and the dication 2 behaves as an oxidizing agent.
  • Hazime Saitô, Junko, Yamada, Yuko Yoshioka, Yûkô Shibata, Tomoki Erata
    Biopolymers 31 8 933 - 940 1991年07月 [査読有り][通常論文]
     
    High-resolution solid-state C-13-nmr spectra of (1 --> 3)-beta-D-xylan from Bryopsis maxima and Caulerpa brachypus were recorded for various preparations from intact through dried frond to anhydrous and hydrated xylan, to gain insight into their secondary structures as compared with those of (1 --> 3)-beta-D-glucans. It turned out that C-13-nmr peaks of intact or dried frond were mainly ascribed to the peaks from (1 --> 3)-beta-D-linked xylose residue, although some peaks were seen at the carbonyl and aliphatic regions. Dehydration of frond by either air drying or ethanol, and extraction of xylan with acid, did not result in substantial spectral change, although extraction with saturated ZnCl2 solution caused appreciable displacements of the C-3 as well as C-2 and C-5 peaks. This means that no major conformational change was induced during the above-mentioned processes of the dehydration and the extraction with acid. The extraction with ZnCl2 solution, however, induced major conformational change. Thus, we found that the above-mentioned three distinct conformations-triple helix, single helix, and single chain-are also present in (1 --> 3)-beta-D-xylan, as judged from the conformation-dependent displacements of C-13 chemical shifts, hydration/dehydration-induced spectral change, and the x-ray diffraction data on Penicillus dumetosus by Atkins et al. In particular, we found that all the preparations except for the extraction with ZnCl2 solution retain the triple helix form, whereas the anhydrous and hydrate samples of the latter preparations take the single-chain and single-helix form, respectively. Further, we measured the C-13 spin-lattice relaxation times of laboratory frame of the xylan to gain insight into better understanding of the role of the hydroxymethyl group as an efficient relaxation pathway in (1 --> 3)-beta-D-glucan.
  • S OGAWA, S SATO, T ERATA, N FURUKAWA
    TETRAHEDRON LETTERS 32 27 3179 - 3182 1991年07月 [査読有り][通常論文]
     
    First evidence for the formation of tetraaryl selenuranes was presented in the reaction of triphenyl selenonium salt or 2,2'-biphenylylene phenyl selenonium salt with phenyllithium by Se-77, H-1, C-13 and CH-COSY NMR studies at low temperature. These selenuranes were also formed in the reactions of the corresponding selenoxides with two equivalents of phenyllithium.
  • Hisashi Fujihara, Hisatomo Mima, Tomoki Erata, Naomichi Furukawa
    Journal of Chemical Society, Chemical Communication 2 98 - 99 1991年01月 [査読有り][通常論文]
     
    A new heterocycle containing selenium and nitrogen atoms, N-methyl-5H,7H-dibenzo[b,g][1,5]selenazocine 1, has been synthesized; the reaction of the selenoxide of 1 with (CF3SO2)2O gave a novel selenaza dication salt which was characterized by Se-77 NMR spectroscopy, and the dication acts as an oxidizing agent.
  • Y AMAKO, T NAKA, M ONODA, H NAGASAWA, T ERATA
    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 59 6 2241 - 2250 1990年06月 [査読有り][通常論文]
  • Hisashi Fujihara, Ryouichi Akaishi, Tomoki Erata, Naomichi Furukawa
    J. Chem. Soc., Chem. Commun. 23 1789 - 1790 1989年12月 [査読有り][通常論文]
  • Y ONODA, M WATANABE, Y FUJIKI, Y KUDO, T ERATA, S YOSHIKADO, T OHACHI, TANIGUCHI, I
    SOLID STATE IONICS 28 179 - 184 1988年09月 [査読有り][通常論文]
  • Saitô Hazime, Tabeta Ryoko, Yokoi Motoko, Erata Tomoki
    Bulletin of Chemical Scociety of Japan 60 12 4259 - 4266 1987年12月 [査読有り][通常論文]
  • O LUTZ, T ERATA, H FORSTER, D MULLER
    NATURWISSENSCHAFTEN 73 2 97 - 99 1986年02月 [査読有り][通常論文]
  • H NAGASAWA, T ERATA, M ONODA, H SUZUKI, S UJI, Y KANAI, S KAGOSHIMA
    MOLECULAR CRYSTALS AND LIQUID CRYSTALS 121 1-4 121 - 124 1985年 [査読有り][通常論文]
  • T Erata, H Nagasawa
    Journal of the Physical Society of Japan 52 10 3652 - 3659 1983年 [査読有り][通常論文]
  • H. Nagasawa, T. Erata, M. Onoda, H. Suzuki, Y. Kanai, S. Kagoshima
    J. Mag. & Mag. Mater. 31-34 1153 - 1154 1983年 [査読有り][通常論文]
  • Stronge Electron Phonon Interaction in Quasi One Dimensional Conductor MxV2O5 Systems
    H. Nagasawa, T. Erata, M. Onoda, H. Suzuki, Y. Kanai, S. Kagoshima
    J. Phys. (France) 44 C3-1737 - C3-1740 1983年 [査読有り][通常論文]
  • H. Nagasawa, T. Takahashi, T. Erata, M. Onoda, Y. Kanai, S. Kagoshima
    Molecular Crystals and Liquid Crystals 86 1-4 1935 - 1942 1982年 [査読有り][通常論文]
  • T Erata, T Takahashi, H Nagasawa
    Solid State Communications 39 2 321 - 324 1981年 [査読有り][通常論文]

MISC

書籍等出版物

  • 物性測定の進歩I
    惠良田知樹 (担当:共著範囲:1章1.6)
    丸善株式会社 1997年10月

講演・口頭発表等

  • セルロース分子のコンフォメーション変化が結晶化に与える影響の検討  [通常講演]
    野村智, 佐藤信一郎, 惠良田知樹
    セルロース学会年次大会 2018年07月 ポスター発表
  • Computational Chemistry Approach on the Change of Hydrogen Bonding Network of Cellulose I and II  [通常講演]
    Satoshi Nomura, Shin-ichiro Sato, Tomoki Erata
    International Cellulose Conference 2017 2017年10月 ポスター発表
  • NMR 法を用いた酢酸菌 ATCC23769 のセルロース生合成経路の精密定量解析  [通常講演]
    牧野礼佳, 野村 智, 惠良田知樹
    セルロース学会年次大会 2017年07月 ポスター発表
  • 新規回転螺旋型リアクターによるバクテリアセルロースの連続生合成  [通常講演]
    惠良田知樹, 野村智, 牧野礼佳, 加納理宏
    セルロース学会年次大会 2017年07月 ポスター発表

所属学協会

  • セルロース学会   


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