武田（本間）志乃　HOMMA-TAKEDA Shino^[1]、西村　義一　NISHIMURA Yoshikazu^[1]、渡辺　嘉人　WATANABE Yoshito^[1]、湯川　雅枝　YUKAWA Masae^[1]、上野　俊治　UENO Shunji^[2]、寺田　靖子　TERADA Yasuko^[3]

^[1]放射線医学総合研究所　National Institute of Radiological Sciences、^[2]北里大学　獣医畜産学部　Kitasato University, School of Veterinary Medicine & Animal Sciences、^[3]（財）高輝度光科学研究センター　JASRI

Abstract: Organotin compounds are widely used in industry and its environmental contamination by these compounds has recently become a concern. It is known that they act as endocrine disruptors but details of the dynamics of Sn in reproductive organs are still unknown. In the present study, we attempted to determine Sn in the testis of rats exposed to tributyltin chloride (TBTC) cell-selectively by synchrotron radiation X-ray florescence analysis with nanoprobe. TBTC was orally administered to rats at a dose of 45 µmol/kg per day for 3 days. One day later, Sn was detected in spermatozoa at the stage VIII seminiferous tubule, which are the final step of spermatogenesis in the testis. Sn levels in the microdissectioned seminiferous tubules determined by inductively coupled argon plasma-mass spectrometry were approximately equivalent to that in the testis. These data indicate that Sn accumulates in germ cells as well as in spermatozoa in a short period of TBTC exposure.

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低温・強磁場下における放射光X線回折測定
Synchrotron X-ray Diffraction Studies under High Magnetic Fields and Low Temperatures

勝又　紘一　KATSUMATA Koichi

（独）理化学研究所　播磨研究所　Harima Institute, RIKEN

Abstract: Diffraction studies of magnetic materials subjected to extreme conditions are illustrated with observations made by non-resonant X-ray diffraction, using beam-line BL19LXU at SPring-8, on materials held in high magnetic fields and low temperatures. The first observation is that of a giant magneto-volume effect in solid oxygen. From this finding, we confirm that magnetic interactions between oxygen molecules are a vital ingredient in determining the crystal structure. A second example is the determination of the high-field phase of a spin-Peierls system CuGeO₃. The X-ray diffraction pattern was measured in a magnetic field, H, up to 15 T. We find that the temperature dependence of the incommensurate peak is quite different at lower H from that at higher H, which is interpreted as stabilization of the incommensurate state by suppression of thermal fluctuations that is brought about by application of a magnetic field. The third example entails diffraction measurements on a sample held at a very low temperature. We observed a jump in the lattice constant of the ladder-like compound Cu₂(C₅H₁₂N₂)₂Cl₄ at about 40 mK associated with the field-induced magnetic ordering from the non-magnetic spin-liquid state. This is the first experimental confirmation of the theoretical prediction on the generalized spin-Peierls phenomenon in quantum magnets. Finally, future prospects are given.

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生体分子の軟X線円二色性の初測定
First Observation of Soft X-ray Circular Dichroism for Biomolecules

中川　和道　NAKAGAWA Kazumichi

神戸大学　発達科学部　Faculty of Human Development, kobe University

Abstract: Circular dichroism spectra of evaporated films of two amino acids (Phenylalanine and Serine) were measured at the soft X-ray energy region for the first time. Magnitude of signal was 0.1 % of the absorption coefficient. Asymmetric reaction will be explored from a view point of origin of life.

Pages 351 - 354 Download PDF (132.33 KB)