Volume 04, No.4
目次 / Table of Contents
July issue 1999
1. ハイライト／HIGHLIGHT
2. SPring-8の現状／PRESENT STATUS OF SPring-8
3. 共用ビームライン／PUBLIC BEAMLINE
4. 原研･理研･R&Dビームライン／JAERI･RIKEN･R&D BEAMLINE
㈱日立製作所 基礎研究所 Advanced Research Laboratory, Hitachi, Ltd.
- Abstract
- Beamline BL16XU at SPring-8, together with its sister beamline BL16B2, was designed and constructed by an industrial consortium of 13 companies to characterize various materials developed for industrial purposes. The main experiments are fluorescence X-ray analysis and X-ray diffraction using X-ray beam of several tens-µm to sub-mm size. Optics for several-µm X-ray beam will also be available for characterization of sophisticated thin film devices and new fine structured materials.
日本電気㈱ 基礎研究所 Fundamental Research Laboratories, NEC Corporation
- Abstract
- Beamline BL16B2, together with its sister beamline BL16XU, is designed and constructed by an industrial consortium of 13 companies to characterize various materials developed for industrial purposes. The main experiments on this beamline are XAFS and X-ray topography, and in some cases X-ray diffraction and X-ray fluorescent analysis. The energy range from the titanium K-edge to the thulium K-edge is covered.
理化学研究所 X線干渉光学研究室 The Institute of Physical and Chemical Research (RIKEN)
5. 最近の研究から／FROM LATEST RESEARCH
（財）高輝度光科学研究センター 放射光研究所 利用促進部門 JASRI Experimental Facilities Division
- Abstract
- In order to analyze the local structure of heterogeneous system, the 'capacitance-XAFS' by measuring the x-ray photon-energy dependence of the capacitance of a Schottky barrier diode is proposed. Since the capacitance is sensitive to the localized electron in the deep level, dropping of the electron into a core hole arising from X-ray absorption of the atom in the deep level, not the bulk atom, increases the capacitance. The site-selectivity of the capacitance XAFS is successfully applied to AlGaAs:Se system. Several applications of the capacitance-XAFS to heterogeneous system, such as the interface XAFS, are introduced.
京都大学大学院 理学研究科 Division of Chemistry, Graduate School of Science, Kyoto University
- Abstract
- Hydrogenases are enzymes which are responsible for the hydrogen metabolism in bacteria. The active site of the [NiFe] hydrogenase has been reported as a hetero binuclear Ni-Fe complex with four non-protein ligands. The Ni atom is coordinated by four sulfur atoms of cysteinyl residues, and two of them coordinate to the Fe atom making the bridges between two metal atoms. The four non-protein ligands of the [NiFe] hydrogenase from D. vulgaris Miyazaki F in the oxidized form were assigned as SO, CO, CN and S. In contrast, those in the hydrogenase from D. gigas were reported as CO, CN, CN and O. Recently we found that the hydrogenase of Miyazaki strain liberated H2S upon reduction with H2 in the presence of its electron carrier. The x-ray crystal structure of the H2-reduced form of the Miyazaki enzyme at 1.4 Å resolution was successfully solved and refined to a crystallographic R-factor of 21.8 %. Though the structure was almost identical to that of the oxidized form, the non-protein monatomic bridge which was observed between the Ni and Fe atoms in the oxidized form disappeared. Considering the experimental results mentioned above, we have concluded that the monatomic bridge ligand between the Ni and Fe atoms must not be a oxygen species but a sulfur species, and this ligand should be removed as H2S when the enzyme is activated upon reduction with H2. This sulfur bridging ligand may have an essential key role for the catalytic cycle of the [NiFe] hydrogenase.
6. 研究会等報告／WORKSHOP AND COMMITTEE REPORT
（財）高輝度光科学研究センター 放射光研究所 ビームライン部門 JASRI Beamline Division、理化学研究所・播磨研究所 RIKEN Harima Institute
（財）高輝度光科学研究センタ− 技術支援方策検討委員会 委員長 姫路工業大学 理学部 Faculty of Science, Himeji Institute of Technology
