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Shibuya-ku, Japan

Results of the recent considerations of the relationship between solution viscosity and molecular shape, based on the experimental results from H. Staudinger's school, are presented. The degree of polymerization is used instead of the molecular weight or the molecular length. The synthetic threadlike polymer polyvinylbenzene or polystyrene is found to be the most frequently used to validate the experimental formula of Staudinger. The experimental results formally provide an actual example of Kuhn's purely theoretical formula for the freely bending threadlike molecules. There is significant evidence to support the occurrence of intramolecular association. The results also show that the solvating low molecules work as if they were side chains of the polymers themselves, which reduces the flexibility of the polymer chains. Source

Kato A.,Tokyo Institute of Technology | Maeno Y.,Ebisu | Hirose S.,Tokyo Institute of Technology
Ichthyological Research

The grass puffer, Takifugu niphobles, is a peripheral freshwater fish often seen in brackish water. In the Sai River, Miyazu, Japan, we found that the grass puffer migrate to fresh water from salt water in June and July. Most of the grass puffer stayed in fresh water for 3.6 h on average and returned to the sea during the day. A low salinity tolerance experiment indicated that the grass puffer can live in fresh water for 2 days but not for longer than 4 days. Based on these findings, we discuss the physiological effects and ecological implications of the migration. © 2010 The Ichthyological Society of Japan. Source

Laskowski R.A.,European Bioinformatics Institute | Swindells M.B.,Ebisu
Journal of Chemical Information and Modeling

We describe a graphical system for automatically generating multiple 2D diagrams of ligand-protein interactions from 3D coordinates. The diagrams portray the hydrogen-bond interaction patterns and hydrophobic contacts between the ligand(s) and the main-chain or side-chain elements of the protein. The system is able to plot, in the same orientation, related sets of ligand-protein interactions. This facilitates popular research tasks, such as analyzing a series of small molecules binding to the same protein target, a single ligand binding to homologous proteins, or the completely general case where both protein and ligand change. © 2011 American Chemical Society. Source

Sakurada I.,Ebisu
Polymer Journal

Various representative forms of mixed polymerization reactions are explained by applying the mechanisms of activation and growth. It is reported that stilbene and maleic anhydride are difficult to polymerize independently, but polymerization proceeds easily when they are mixed. It is reported that stilbene and maleic anhydride are difficult to polymerize independently, but polymerization proceeds easily when they are mixed. If any of the four rate constants for a growth reaction are non-zero and comparable in magnitude to one another, a copolymer is produced. The production of true copolymers is controlled by the active site species in the growth reaction and is independent of the identity of the monomer added. The experimental results of the mixed polymerization of acrylonitrile and vinyl acetate, obtained by Okamura, Ota, and other members of our laboratory are in good agreement with the proposed theory. Source

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