| Co-Investigator(Kenkyū-buntansha) |
KATO Minoru Department of Chemistry, Ritsumeikan University, Lecturer, 理工学部, 講師 (00241258)
OZUTSUMI Kazuhiko Department of Chemistry, Ritsumeikan University, Associate Professor, 理工学部, 助教授 (50177250)
SAWAMURA Seiji Department of Chemistry, Ritsumeikan University, Associate Professor, 理工学部, 助教授 (10167439)
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| Research Abstract |
The following results have been obtained by this project.
1) Structure of water under high temperatures and high pressures (HTHP) has been investigated by using an HTHP solution X-ray diffractometer. From the analysis of the radial distribution functions obtained it was found that a large extent of the H-bonding water structure was destroyes at high temperatures and high pressures, but still H-bonds in water remain to some extent, say, a few decades percentage, even at the critical point of water to keep the nearest intermolecular water-water distance to be 290-295 pm, which was elongated from that of the water-water distance in the normal water, 280-185 pm. On the other hand, the number of water molecules at the nearest neighbor (the coordination number, n) decreased to about 1.5. From these results it was concluded that water at HTHP consists of clusters containing rather small number of water molecules, even smaller oligomers, and monomeric water molecules. The conclusion derived by
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this study can explain properties of supercritical water quite well. Solution X-ray diffraction and NMR studies have been examined for some aqueous solutions under the normal condition.
2) The B-coefficients of viscosity of various aquenous electrolyte solutions have been determined at high pressures over a medium temperature range to investigate the structural changes of aqueous solutions with pressure. Dynamic properties of hydrated water molecules have been studied by using the NMR method. The B-coefficient increased with pressure at a relatively low temperature, but it decreased with the further increase in pressure, and thus, the B-coefficient showed a maximum at a certain pressure. At a constant pressure the B-coefficient increased with temperature and then decreased after passing through a maximum. At high temperatures the B-coefficient monotonously decreased with pressure. These changes in the B-coefficient of viscosity reflected the change of the water structure with temperature and pressure. The rotational motion of hydrated water molecules around alkaline ions was found to slow down with pressure.
3) Structural changes of proteins with pressure have been discussed by using Raman spectroscopy, FT-IR,and small-angle X-ray diffraction method. Less
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