Motoyoshi Hatada

Protein permeation through poly(vinyl alcohol) hydrogel membranes

Hydrogel membranes were prepared by radiation and chemical cross-linking of poly(vinyl alcohol) (PVA) in aqueous solutions. Effects of PVA concentration, PVA molecular weight and radiation dose, as well as concentration of cross-linking agent, in the case of the chemical cross-linking procedure, on the permeation of insulin, albumin and immunoglobulin (IgG) through the membranes were investigated. Glucose permeation was also studied. The cross-linking density affected the size of the macromolecular mesh of the hydrogel network and thus the water content of the membrane responsible for the diffusion of the solutes. The diffusion coefficient linearly increased for all the solutes with increasing water content in the PVA hydrogels, indicating that diffusion occurs primarily through the water hydrating the polymer network. The permeability study showed that the water content as well as the mesh size had an influence on the diffusion of low molecular weight glucose and insulin. Although the diffusion of higher molecular weight solutes, such as albumin and IgG, was not so much affected by the mesh size of elaborated PVA hydrogel membranes, the diffusion of these proteins was very low.

Preparation of hydrogels by radiation technique

Abstract Moderately concentrated, aqueous solutions of poly(vinyl alcohol) (PVA), poly(ethylene oxide), polyacrylamide, polyvinylpyrrolidone, and methyl cellulose were cast on a glass plate and irradiated with electron beams to yield crosslinked hydrogels. Irradiation was carried out also for water-swollen films of PVA. In all cases, no attempt was made to expel air from the polymer-water mixture to be irradiated, since the hydrogels were readily formed by placing a glass plate or a plastics film on the mixture. The measurement of tensile properties of the hydrogels revealed that the hydrogel from PVA, especially prepared by irradiation of water-swollen films, gave the highest tensile strength among the hydrogels. The swelling of once dried PVA hydrogels was recovered almost to the initial swelling state when boiled in water.

Effect of irradiation temperature on the radiolysis of methane

Abstract The G-values of most products increase with temperature in the radiolysis of methane in a flow-type experiment over the temperature range 50–280°C at atmospheric pressure. The apparent activation energies of most products are higher at higher temperature region above 150°C than those obtained below about 100°C. Irradiation at higher temperature favors the formation of olefins. The results are qualitatively understood on the basis of known nature and reactivity of free radicals.

Fabrication of self-assembled monolayer patterns by selective electron beam irradiation and a chemical adsorption technique

Abstract Self-assembled monolayer patterns have been fabricated on silicon dioxide/silicon substrates by a chemical adsorption (CA) technique from 18-nonadecenyltrichlorosilane, 9-(heptadecafluorodecyl-dimethylsilyl) nonyltrichlorosilane etc. and a selective electron beam irradiation in a nitrogen atmosphere through an SUS mask. The fabrication of CA monolayer patterns was well confirmed by an X-ray photoelectron spectroscopy measurement, a contact angle measurement and film thickness measurement. A fine line and space pattern are fabricated in this study.

Low energy electron-impact emission from gases☆

Abstract To investigate higher excited states, including the superexcited states proposed by Platzman, a method was developed to analyse the entire emission spectra from the gases electron-bombarded with electrons of energy lower than 300 eV. From several standpoints (energetic relations, cascading processes and kinetic isotopic effects), the existence of the higher excited states could be confirmed in some simple aliphatic and aromatic compounds. On the basis of the results, their fragmentation schemes in radiolysis are discussed. The most extensive conclusions were drawn on comparing the ratio of H and D atoms produced from partially deuterated compounds by measuring the intensity of the corresponding Balmer lines.

Radiation-induced polymerization of monomolecular film of octadecyl acrylate at gas-water interface

Abstract Studies have been carried out on radiation-induced polymerization of octadecylacrylate monolayers at gas-water interface using automatic surface balance techniques. The monolayers were irradiated with electron beams from a Van de Graaff electron accelerator either at a nitrogen-water or at an air-water interface, and the reaction was followed by measuring surface pressure-area curves at intervals or by recording surface pressure change during irradiation. The polymerization was found to proceed at the nitrogen-water interface, while no indication of the formation of poly(octaclecyl acrylate) was obtained for the monolayer when irradiated at the air-water interface.

Radiolysis of methane containing small amounts of carbon monoxide—formation of organic acids

Electron beam irradiation of methane containing small amounts of carbon monoxide in a flow system at atmospheric pressure produced acetic and propionic acids in considerable yields. Propionic acid was formed in preference to acetic acid, especially at small molar ratios, [CO]/[CH4]. These acids were though to be formed via Koch-Haaf reactions CH3++CO→CH3CO+→H2OCH3COOH2+C2H5++CO→C2H5CO+→H2OC2H5COOH2+ The decrease in G(H2) observed by the addition of CO to methane was interpreted on the basis of the following reaction H+CO→k2HCO The estimated values of k2 were close to the reported value.

Radiation effects on COH2 gas mixture in the presence of silica gel

Abstract Electron beam irradiation of gas mixture of CO and H2 (1:6) in the presence of silica gel exclusively produces carbon dioxide and hydrocarbons in high yields. At the reaction temperature of 140°C, CO2 is preferentially produced, most of which are formed independently of hydrocarbons. The yields of hydrocarbons consisting predominantly of low molecular weight paraffins, obtained at 295°C, were higher by more than an order of magnitude than those by the homogeneous radiolysis and comparable to those by catalytic reactions over Fischer-Tropsch catalyst. Results obtained by irradiation of H2 over silica gel pre-irradiated under COHe gas stream indicate that secondary reactions between H2 and solid deposits produced from CO are responsible for the formation of hydrocarbons in the radiolysis of the COH2 mixture over silica gel.

Radiation effects on Fischer-Tropsch syntheses

Abstract Radiation effect on Fischer-Tropsch synthesis has been examined using high dose rate electron beams and Fe-Cu-diatomaceous earth catalyst. Yields of saturated hydrocarbons were found to increase by irradiation, but the yields of these compounds were decreased by raising reaction temperature without irradiation, suggesting the presence of radiation chemical process in catalytic reactions.

Radiation effect of a high energy electron beam on thin films of saturated and unsaturated fatty acids

Studies have been carried out on electron beam induced polymerization of LB films of saturated and unsaturated long chain aliphatic acids, in an attempt to obtain information about the dose dependence of conversion in relation to molecular arrangement. The results indicate that polymerization of unsaturated aliphatic acid LB films occurred when irradiation was carried out in a nitrogen atmosphere and that the LB films of a disordered state are more sensitive to radiation than tightly packed LB films.