[en] Dicyclohexano-18-crown-6 (DC18C6), dissolved in chloroform, 1-octanol, toluene or cyclohexane, was irradiated by ⁶⁰Co γ-rays. Radiolytic destruction of DC18C6, measured by gas chromatography, decreased in the order: chloroform > cyclohexane > 1-octanol > toluene. Distribution coefficients in the solvent extraction of strontium from nitric acid solution were measured. These distribution coefficients were minimally affected by γ-irradiation in toluene solution, but decreased with the absorbed dose in chloroform solution. It was suggested that the distribution coefficient for the liquid-liquid extraction system was influenced by radiolytic products. The effect of radiolytic products on the distribution coefficients was evaluated by considering DC18C6 remaining in the organic phase after irradiation. The distribution coefficient measured for the organic phase with radiolytic products was larger than that without radiolytic products. The radiolytic products were thus shown to contribute to the increase in the distribution coefficient

[en] In a previous report, the conformation of polytetrahydrofuran (PTHF) in isopropyl alcohol as a theta solvent and in n-butyl alcohol as an intermediate solvent was examined by the small angle scattering of X-ray. As the result, the experimental scattering curve at theta temperature was explained well with the calculated curve obtained by superposing, while it was impossible to apply the similar method to the analysis of the scattering curve in the intermediate solvent. Recently, as the results of the calculation by Koyama on the angular distribution of light intensity scattered by stiff chain polymers and of the studies by Edwards and de Gennes on the asymptotic behavior of scattering curves in good solvents, the direct comparison of experimental and calculated scattering curves became possible. In this report, the comparison of the scattering curves of PTHF-alcohol systems is described. The systems employed were PTHF-n-propyl alcohol, PTHF-isobutyl alcohol, PTHF-sec-butyl alcohol, and PTHF-tert-butyl alcohol in addition to the previous two systems. The Guinier plots of the cross section factors of the PTHF-alcohol systems showed that the Guinier approximation on cross sections was not satisfied in cases of PTHF-isobutyl alcohol and PTHF-sec-butyl alcohol. The light scattering data at 44.6⁰ C, the theta temperature of PTHF-isopropyl alcohol, are given. From the figures comparing experimental and calculated scattering curves, it was shown that there was appreciable solvent effect on the scattering curves of PTHF-alcohol systems. The relation predicted by Edwards and de Gennes was satisfied well in case of the systems in good solvents. (Kako, I.)

[en] The effect of low doses of ultraviolet (UV) irradiation on morphology changes of cell has been studied based on the observation of the cell length. It was shown that UV-irradiated cell has different behavior in comparison with nonirradiated cell. From the histogram of cell-length distribution, it was confirmed that cell cycle of non irradiated cell was 28 hours, and that cell cycle of irradiated cell with dose of 20 Jm^-2 was delayed (39 hours), while irradiated cell with 40 Jm^-2 and 60 Jm^-2 did not divide and kept growing continuously. It was supposed that in case of 20 Jm^-2 of irradiation dose, the cell cycle was delayed because the checkpoint worked in order to repair DNA damage induced by generation of pyrimidine dimer, reactive oxygen species and so on. It was also supposed that in case of 40 Jm^-2 and 60 Jm^-2 of irradiation dose, overgrowth was induced because the checkpoint was not worked well. The morphology of overgrown cell was similar to that of normally senescent cell. Therefore, it was considered that cell senescence was accelerated by UV irradiation with irradiation doses of 40 Jm^-2 and 60 Jm^-2

[en] In order to improve the radiation stability of aliphatic polymers, radiation-induced graft polymerization of styrene onto low-density polyethylene (LDPE) has been studied. Two methods, namely, simultaneous irradiation and pre-irradiation method, were treated. In the case of simultaneous irradiation, it was indicated from the dependency of percent graft on monomer concentration and absorbed dose that grafting efficiency was reduced by the increase in the homo-polymerization of styrene. On the other hand, more highly grafting polymer could be prepared by the pre-irradiation method. Depth-profile of grafted phenyl ring was also analyzed by means of micro-FT-IR spectroscopy. Recently, radiation stability of the obtained graft polymer was tested

[en] Hybridization of a thermo-responsive N-isopropylacrylamide (NIPAAm) hydrogel with poly(vinyl chloride) (PVC) has been studied in order to improve its mechanical property without compensation for its functionality. In this study, a simultaneous radiation grafting method was applied to the hybridization. In an aqueous solution containing NIPAAm monomers without contacting to PVC, effective radiation-induced polymerization of NIPAAm was achieved. In the presence of a PVC film, graft polymers composed of PVC and NIPAAm was obtained. The graft polymers manifested the thermo-responsive deformation repeatedly. (author)

[en] In the study, we examined the effect of hydroxyl radical generated by γ-ray and UV irradiation on shrinkage of vitreous body. Change in gel ratio of vitreous body and change in the properties of its components (collagen, sodium hyaluronate) were analyzed. By comparing these results, the amount of hydroxyl radical, which induces the considerable shrinkage of vitreous body, was evaluated from theoretical calculation based on experimental condition and some reported kinetic parameters. It was concluded that the integrated amount of hydroxyl radical required to liquefy half of the vitreous body (vitreous body gel ratio = 50%) was estimated as 140 μmolg^-1 from γ-ray irradiation experiment. Also, from UV irradiation experiment result, it was confirmed that the effect of hydroxyl radical is larger than that of other reactive species. The causes of shrinkage of vitreous body are supposed as follows, 1) decrease in viscosity by cleavage of glycoside bond in sodium hyaluronate, 2) leaching of collagen from vitreous body and 3) leaching of crosslinked products and scission products of collagen

[en] The STRACASOL work showed that the availability of new experimental and theoretical tools brought about some important changes in the physics of polymers. There are still full of challenging problems in polymers and biopolymers, which will require a long and patient effort of understanding. A pleasant cooperation among the relevant different fields and an appropriate sample preparation will conquer difficulties expected. (author)

[en] Two types of silica were used: one is Aerosil-130 silica, which is easily aggregated in water and the other is Snowtex-C dispersed in water. These silicas were mixed with an aqueous solution of hydroxypropyl methyl cellulose (HPMC) that adsorbs on the silica surfaces to make silica suspensions. Small angle neutron scattering (SANS) technique was used to understand the structures and interactions of the silica suspensions and the corresponding silica slurries (no HPMC) as functions of HPMC and silica content. The wave vector q was ranged 0.03 to 0.8 nm^-1. In the scattering curves for Aerosil silica slurries and suspensions below q = 0.1 nm^-1, a power-law exponent of 2.1 was obtained independent of silica content. The scattering curves at higher q, however, approached a power-law scattering with an exponent of -4, namely followed the Porod's law. It was found that adsorption of HPMC did not effect on the scattering curves. On the other hand, for Snowtex-C the peak was observed at the intermediate q in the scattering curves, whose position shifts to higher q with an increase in silica content, indicating that an average distance between silica particles decreases. Snowtex-C suspensions showed an increase in scattering intensity below q = 0.1 nm^-1 by adsorption of HPMC. (author)

[en] Beams of organic ion which have an amino functional group like ⁺CH₂NH₂ were generated by using n-propylamine as an ion source gas with an organic beam accelerator. The current density of ⁺CH₂NH₂ beam was 7.5 nA/cm² at 30 keV. (author)

[en] Protection effects by aromatic compounds in irradiated liquid n-dodecane were studied as a model experiment for the radiolysis of aliphatic polymers. Final products of γ-radiolysis were analyzed by gas chromatography, while reactivity of additives towards reactive intermediate species was analyzed by pulse radiolysis. The yield of scission products was well reduced by increase of the degree of aromaticity and concentration of additives; moreover, the higher the degree of aromaticity of additive, the higher was the reactivity of additive towards excited molecules, radical cations, and electrons. In conclusion, reactivity between additive and reactive intermediate species is an important factor of radiation protection