The Philippine-Sea plate in the northwestern Pacific Ocean is moving horizontally toward N55°W at rates of 40 to 90mm/yr (greater southward) relative to underlying asthenosphere. The Palau and Yap Trenches situated at its southeastern margin are moving together with the Philippine-Sea plate. Resistance of viscous asthenosphere against vertically subducted rigid slabs is estimated based upon a simple viscous flow model. It has been shown that appreciably large uplifting pressure is generated in the frontal zone of the vertical slab, while tectonic erosion in the trench bottom proceeds both under the influence of the viscous flow. This model may reasonably explain enigmatic features of the Palau and Yap Trench-Arc systems revealed by detailed topographic mapping and submersible investigation such as (1) large water depths (exceeding 8000m) in spite of their extremely small plate convergence rates, (2) exposure of serpentinized peridotite, gabbro and basalt despite a large amount of slope failure deposits containing a huge reefal limestone block, (3) abnormally close proximity of islands to the trench axis, (4) deficiency of barrier reefs on their trench-facing side in spite of the easterly to northeasterly prevailing wind.
Wooden anchors equipped with a pair of granitic anchor stones were found and recovered form a number of submerged wrecks located in Imari Bay of Takashima, Nagasaki Prefecture. These remains are from wrecked Mongolian warships that were involved in the second Mongol invasion of 1281. All the granitic anchor stones from different anchors are alkali granite, consisting mainly of microcline-micro-perthite and quartz with trace amounts of biotite and plagioclase. The CHIME (chemical Th-U-total Pb isochron method) age determination was carried out on zircons from the recovered granitic anchor stones to try to identify the original source area for the anchor stones. The CHIME zircon ages for 3 anchor stones from different anchors are 110±1Ma, 108±3Ma and 108±2Ma. The ages together with the Sr-poor nature of the bulk chemistry suggest that the anchor stones were derived from a leucocratic alkali granite body found close to Quanzhou, southeastern China. This result implies that the wrecked warships were constructed in Quanzhou and supports the view that the Moslem traders in Quanzhou contributed significantly to the second Mongol invasion by providing ships and seamen.
Organic thin films in which DNA double strands aligned in one direction were prepared by two methods: i) the polyion complex of DNA anions and cationic amphiphiles was prepared, the organic solution of the DNA-lipid complex was cast on the plate, and the obtained transparent film was stretched in one direction, and ii) DNA anions were solubilized in subphase with intercalated dyes and were transferred with cationic lipid monolayers by vertical dipping method. DNA strands could be aligned along stretching direction in the cast film and along dipping direction in the Langmuir-Blodgett (LB) film. The orientation of DNA strands in these thin films was confirmed by X-ray diffraction and polarized absorption spectra. The DNA-aligned films prepared by both cast-stretching and LB methods showed a large anisotropic and ohmic electric current (10-3-10-5 S cm-1 ratio=104) along DNA strands in the film.