Reaction between molten iron and silicate at high pressure and temperature was examined by employing a mixture of pure iron and (Mg0.9Fe0.1)2SiO4 olivine as the starting material. The experimental charge quenched at 24 GPa and 2550°C demonstrated that certain amount of SiO2 component (at least 2wt% of Si) dissolved into mol ten iron fromthe silicate melt. It is suggested that the dissolving would be enhanced with increasing pressure. The experimental results indicate that Si and O are the important alloying light-elements in the earth's core if the core segregation proceeded in the magma ocean of the proto-earth. Concurrently, SiO2 contents of the mantle should be substantially reduced from its primitive content.
In situ X-ray observation under high pressure was carried out to investigate the phase transformation in graphite induced by room temperature compression. Several diffraction peaks of the high pressure phase were clearly observed and could be indexed as a hexagonal diamond structure. The diffraction profiles from two different directions support the orientation relationship of the martensitic transformation from graphite to hexagonal diamond previously proposed. This hexagonal diamond has a large bulk modulus comparable to the cubic diamond.
Precardiac mesoderm (PCM) of chick embryo at stage 5 was excised with or without endoderm and ectoderm and cultured in vitro using Eagle's minimum essential medium (MEM) as a basic medium. PCM placed alone in MEM degenerated. When PCM was associated with endoderm, it produced beating tissue in MEM, while it did not show pulsation with ectoderm in the same condition. If MEM was supplemented with 15% horse serum, PCM developed into beating tissue without endoderm. Insulin (25μg/ml) was effective in differentiation of PCM to myocardial cells.
The ordered structure of polymethylmethacrylate-based latex particles in water dispersions have been studied by the Bonse-Hart type Ultra-small-angle X-ray scattering (USAXS) technique. The scattering patterns resembled a“powder diffraction pattern and distinct diffraction peaks were observed in the scattering curve. The lattice system was concluded to be a face-centered-cubic (fcc) lattice from the relative peak position. These findings indicate that the ordered structure has a limited size and that each ordered region orients randomly in the dispersion.
Electron microscopy revealed that bodywall muscle of the annelid Urechisunicinctus consisted of B type smooth muscle cells containing parallel thick (40nm in diameter) and thin (7nm) filaments. Myosin was extracted from Urechis bodywall muscle and purified to homogeneity. Urechis myosin, two-headed myosin, consisted of 200kDa heavy chain and two species of light chains, 24 and 19kDa. The ATPase activity was approximately 0.1μmole/mg/min in the presence of Ca2+ or EDTA. The Mg2+-ATPase activity was remarkably enhanced from 0.005 to 0.2μmole/mg/min by rabbit skeletal muscle actin. EGTA inhibited this actin-activated ATPase activity suggesting that the regulation by calcium ion is of the scallop type.