A large number of fractures dividing the troilite (FeS) into two distinct layers around metallic grains were observed in chondrite samples (ALH-764 and Y-791717) for the first time in the present study. A similar fracture was successfully reproduced in experiments with iron-meteorite sulfidation. The fracture texture shows that the troilite was formed by reaction between metallic grains mainly composed of Fe-Ni alloy and S-rich gas. The thickness distribution of troilite in chondrites can be used as an indicator of the cooling history of the gas, and as a result, some important constraints can be determined for the formation of chondrites.
This paper describes the synthesis of polymer hybrids between polyoxazoline and silica gel, in which the transition metal salts are incorporated. Organic-inorganic polymer hybrids were prepared by the acid-catalyzed sol-gel reaction of tetraethoxysilane in the presence of poly (2-methyl-2-oxazoline). To this system were added transition metal salts such as cupric chloride, cupric acetate, nickel chloride or palladium chloride. Cupric or nickel salts gave homogeneous and transparent glasses, while palladium salt caused turbid materials. These homogeneous polymer hybrids containing transition metal salts were subjected to pyrolysis at 600°C to eliminate polyoxazoline segments. The resulting porous silica showed high surface area (around 300m2/g). In these porous silica gels, the transition metals should be dispersed homogeneously in the matrix, which can be expected as an effective transition metal catalyst-supported inorganic materials (ceramics).
Supellapyrone [(2R, 4R)-5-(2, 4-dimethylheptyl)-3-methyl-2H-pyran-2-one (1)], the female-produced sex pheromone of the brownbanded cockroach (Supellalongipalpa), was synthesized by starting from mesitol(4).
The present study was undertaken to clarify the minimum level of digested protein required to induce larval molting. Newly-ecdysed fourth-instar larvae of Bombyx mori were reared on semi-synthetic diets containing various doses of protein (5 to 20%, dry weight basis), and the coefficient of digestibility as well as the ecdysteroid level of larval hemolymph was determined. According to the decrease in dietary protein, the ecdysteroid level of hemolymph lowered and the minimum dietary level of protein required to induce molting was found to be 7%. The ecdysteroid level of hemolymph increased when the amount of digested protein exceeded 18mg per larva during the 4th instar. When the protein amount exceeded 19mg, the larvae molted. Larvae reared on a 5% protein diet survived more than 20 days and died without molting. With a 5% protein diet, no increase was recognized in the ecdysteroid level of the larval hemolymph. But when the larvae were fed on a commercial diet in place of the P5-diet, the ecdysteroid level increased, and the larvae were able to molt.
Recent work has suggested that the length of thin filaments in skeletal muscles is determined by a protein ruler, nebulin, located along the long axis of thin filaments. To examine the function of nebulin, the length distribution of the thin filaments was investigated by staining actin filaments with fluorescent rhodamine-phalloidin in rabbit cardiac muscles, which do not contain nebulin, and in skeletal muscles, which contain nebulin, by laser scanning confocal microscopy. The microscopic observation showed a difference in staining patterns between cardiac and skeletal muscle fibers when the staining was done without chemical fixation. This suggests that nebulin suppresses the attachment of phalloidin to actin filaments. Analysis of fluorescence distribution showed that the length deviation of thin filaments in the cardiac muscle was as small as that in the skeletal muscle. This indicates that the length of the thin filaments is regulated even without nebulin.