In order to clarify the effect of non-hydrostaticity of pressure on the crystal lattice of minerals, various pressures with different hydrostaticity were applied to silica (cristobalite) at room temperature and high pressure in situ x-ray observations were made. Under strongly non-hydrostatic compression, cristobalite transformed to an“X-I phase”reported in the previous study, while under quasi-hydrostatic compression, a new polymorph was synthesized. Although the new polymorph gives very similar diffraction profile to stishovite, its unit cell dimension is meaningfully different from that of stishovite. Present study clarified that in cristobalite the crystal structure of high pressure polymorph changes completely depending on the hydrostaticity of applied pressure.
Direct observation and sampling by research submersible Shinkai 6500 together with bathymetric and geophysical survey revealed that sequences of serpentinized peridotite, basalt and limestone are exposed on the landward slope of the Palau Trench. A huge block (larger than 3km2 in horizontal dimension) of coral-reef limestone was discovered at depths ranging from 4, 900m to 6, 500m. The result seems to indicate that extensive slope failure is occurring on the landward slope from which great amount of mass is wasted to the trench axis. Nevertheless, greater portion of the Palau Trench axis has V-shaped bottom with little sediment cover, regardless its very slow rates of plate convergence accompanied with no deep-focus earthquakes. Islands of Palau (Belau) are extraordinarily close to the trench axis and appear to be now uplifted. A hypothesis is postulated to explain this unique situation.
Asymmetric total syntheses of Taxol and of 8-demethyltaxoids 24-27 from the 8-membered ring compounds 29 and 12 respectively were completed via successive formation of the BC ring system by intramolecular aldol reaction, then the ABC ring system utilizing an intramolecular pinacol cyclization. The conversion of the tricyclic compound 43 to 7-TES baccatin III (49) was carried out by way of a newly devised method of constructing the oxetane ring. The dehydration condensation between a derivative of N- benzoylphenylisoserine and 49, followed by deprotection afforded the antitumor agent Taxol.
The synchronous machine are operated extensively, as both AC generators and AC motors, and its utilization is still growing. In spite of its long and old history of its operation, the conventional theories have not provided adequate analytical solutions and explanations of the machine performance, especially in respect to electromagnetic transient phenomena, such as sudden short circuit of the machine. The author proposed the SV method and in this paper he applies it to asymmetrical sudden short circuits of the machine, which have been untouched by the conventional theories.
An insertion sequence (IS1164), which is present in the high-molecular mass nitrile hydratase gene cluster of an industrial strain Rhodococcus rhodochrous J1, has two pairs of terminal inverted repeats flanked by direct repeats and contains an open reading frame encoding a putative transposase. Structures of the terminal region containing the inverted repeats were found to be highly conserved both in IS1164 and in IS1081 from Mycobacterium bovis. Hybridization analyses showed that R. rhodochrous J1 had 2-3 other IS1164-like elements and that 11 out of 16 Rhodococcus strains contained IS1164-like elements varying in copy number from one to at least seven. These elements were present not only in Rhodococcus producing recalcitrant nitriles- degrading enzymes but also in Rhodococcus utilizing alkylbenzenes and hydrocarbons.
Upon tight binding of two molecules, it is frequently observed that NMR chemical shifts change significantly. We propose a novel method that incorporates this information in the model building procedure, so that the atomic model of the complex structure is built without human manipulation. When the chemical shift of an atom is changed significantly, we call it an active atom. Then, we have added a heuristic restraint in the simulated annealing procedure. It gives no penalty when the active atom of a molecule is near at least one of active atoms in the other molecule, but it imposes a large penalty when the active atom is far from the other molecule. The structures of the individual molecules are formed and maintained by the intramolecular distance restraints. Results are shown for a model of an SH3 domain with a polyproline peptide, in which the complex structure can be rebuilt with both a rigid and a flexible ligand peptide.