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Asano, Masaharu; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Yamaguchi, Susumu*; Yamamoto, Kazuya*; Asazawa, Koichiro*; Yamada, Koji*; Tanaka, Hirohisa*
no journal, ,
no abstracts in English
Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Taguchi, Mitsumasa; Seko, Noriaki; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
no abstracts in English
Tago, Takanori; Nagasawa, Naotsugu; Taguchi, Mitsumasa; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
no abstracts in English
Idesaki, Akira; Hakura, Yoshihiko*; Uechi, Hiroki*; Oshima, Takeshi; Kishi, Hajime*
no journal, ,
Relationship between chemical structure of hardeners for epoxy resins and radiation resistance of obtained resins was investigated by gas analysis, bending test, dynamic viscoelasticity measurement, and so on. It was found that epoxy resins which were cured by hardeners containing benzene ring and/or C-N bond in the structure. Especially, epoxy resin which was cured by cyanate ester showed the highest radiation resistance.
Hakoda, Teruyuki; Shimada, Akihiko; Kimura, Atsushi; Taguchi, Mitsumasa; Araki, Koshi*; Hirota, Koichi
no journal, ,
An electron-beam irradiation/catalytic oxidation system was developed for the purification of a volatile organic compound (VOC) gas stream under a practical gas flow condition. The removal of toluene and/or xylene and their mineralization were examined with and without catalytic oxidation for a gas stream at a flow rate of 500 m
/h. A combined catalyst bed enhanced the removal of VOCs and the mineralization of VOC and its irradiation organic byproducts.
Lin, M.; Muroya, Yusa*; Katsumura, Yosuke*; Meesungneon, J.*; Jay-Gerin, J.-P.*; Mostafavi, M.*
no journal, ,
A setup was constructed to conduct picosecond time-resolved pulse radiolysis in UV region. Using this system, a direct observation of the picosecond kinetics of hydroxyl radical in pure H
O, 2.0 M HClO
aqueous solution and pure DO was realized for the first time. A good agreement between the experimental results and Monte-Carlo simulations was demonstrated.
irradiation to aqueous sulfuric acid solutions containing alumina powderYamada, Reiji; Kumagai, Yuta; Nagaishi, Ryuji
no journal, ,
The amounts of hydrogen peroxide produced by irradiation in aqueous and aqueous sulfuric acid solutions containing alumina powder were measured and compared with the results of relevant hydrogen gas production yields. The amounts of hydrogen peroxide were strongly depressed when alumina powders were added to the solutions and the hydrogen production yields were correlatively increased with increasing the amount of added alumina powder. The hydrogen peroxide generally hinders the formation of hydrogen gas in aqueous solutions. Our experimental results suggest that the addition of oxide in aqueous solutions induced the reduction of the concentration of peroxide by which the amounts of emitted hydrogen gas were increased.
Kumagai, Yuta; Muroya, Yusa*; Saiki, Seiichi; Yamada, Reiji; Nagaishi, Ryuji; Katsumura, Yosuke*
no journal, ,
Peculiar radiation effect at the interface between water and silica has been studied by time-resolved observation of the transient behaviors of radicals produced by irradiation in aqueous solution containing colloidal silica using pulse-radiolysis technique. Scavenging reaction of OH radical by colloidal silica was observed and the reactivity was dependent on pH of aqueous solution. On the other hand, the presence of colloidal silica had no significant effect on the decay kinetics of hydrated electron. Therefore the interaction of the interface with OH radical is expected but not with hydrated election Besides, ESR spectrum of transient radicals in the presence of colloidal silica was measured at 77 K. Change in the spectrum shapes of OH radical and HO radical suggests that there were interactions of colloidal silica with the radicals.
Kimura, Atsushi; Taguchi, Mitsumasa; Kondo, Takafumi*; Yang, J.*; Nagaishi, Ryuji; Yoshida, Yoichi*
no journal, ,
no abstracts in English
Hirade, Tetsuya; Oka, Toshitaka
no journal, ,
Pick off annihilation lifetime of ortho-positronium (o-Ps) depends on the size of the bubble formed by the positronium itself. The lifetime is longer at higher temperatures, because of the larger bubble size. However, only water shows reversed temperature dependence and it is considered that there exist more reactions of o-Ps with spur reactants at higher temperatures. Here, we tried to obtain the experimental evidence of these reactions of o-Ps by use of Age-Momentum Correlation measurement of annihilation -rays (AMOC). Obtained S(t) curves indicated in Fig.2 show that there were larger S values for higher temperatures at older positron age region. Larger S values indicate that there exist more spin conversion reactions of o-Ps.
Nagaishi, Ryuji; Aoyagi, Noboru; Taguchi, Mitsumasa; Kondo, Takafumi*; Yang, J.*; Yoshida, Yoichi*
no journal, ,
Reaction behaviors of radiolysis products in mixtures of different ionic liquids containing thiocyanate anion were studied by using pulse radiolysis technique. Dimer radical ion of thiocyanate in the visible range and electron in the near-infrared range were observed in the ns-pulse radiolysis to measure their yields and reactions. The formations of products increased with increasing the thiocyanate concentration, regardless of kinds of cations in the mixture. The products were also observed in the ps-pulse radiolysis to clarify their formation pathways.
Hiroki, Akihiro; Sato, Toshihiro*; Nagasawa, Naotsugu; Taguchi, Mitsumasa; Tamada, Masao
no journal, ,
Modification of mechanical properties of hydroxypropyl cellulose (HPC) gels by blending polyvinyl alcohol (PVA) was investigated. The blend gels constructed with HPC and PVA were prepared by electron beam irradiation to their high concentrated aqueous solution. Gel fraction of the blend gels increased sharply up to 10 kGy, and leveled off at 50 kGy. It was found that PVA content caused a decrease in the gel fraction. Elongation at break of the blend gel obtained at 50 kGy gradually increased with the PVA content beyond 0.4wt%, and reached 125% at 4wt% of PVA, which was about 1.8 times larger than that of the pure HPC gel. Therefore, the HPC hydrogels with desired mechanical properties were obtained by the combination of PVA blending with the radiation crosslinking technique.
Yamashita, Shinichi
no journal, ,
Water radiolysis with heavy-ion beams of energies up to 28 GeV provided from HIMAC, NIRS has been investigated from the viewpoint of correlation of products yields with track structure and its dynamics. For wide variety of heavy-ion beams in terms of LET, velocity, charge, etc., primary yields of major products in water radiolysis, e
, 
OH and HO, have been measured by employing scavenging method to convert transient water radicals into stable and easily detectable species. Temporal behavior of approximate sum of water radicals has also been experimentally estimated. A Monte-Carlo simulation code of water radiolysis developed by a group of Universit
de Sherbrooke, Canada was complementally used in discussion of microscopic track structure and its dynamics. In addition, a fluorescent probe was utilized in sensitive OH detection with HPLC-connected fluorometry.
Fujii, Kentaro
no journal, ,
We have revealed that the yields of base lesions as well as strand breaks strongly depend on soft X-ray energy around carbon, nitrogen and oxygen K-edge regions. The K-shell ionization of oxygen most likely contributes to the induction of nucleobase lesions. DNA single strand breaks, on the other hand, are preferably produced just below N K-edge. To investigate the mechanism of molecular changes in DNA irradiated with soft X-rays, we have also measured the spectra of X-ray absorption near edge structure (XANES) of DNA caused by exposure to monochromatic soft X-rays. The obtained results may provide important implications for selective induction of specific types of DNA damage through tuning the energy of soft X-rays.
Kumada, Takayuki; Noda, Yohei; Ishikawa, Norito; Takegahara, Keisuke*
no journal, ,
We carried out dynamic nuclear polarization study of electron- and ion-beam irradiated polyethylene. We found that grow and decay rates of polarization linearly increased proportional to the concentration of alkyl radicals, whereas they quadratically increased with TEMPO concentration in TEMPO-doped polystylene. This result suggests that pairs of alkyl radicals are produced by the radiolysis. The pair distance is estimated to be less than 1 nm.
Iwamatsu, Kazuhiro; Taguchi, Mitsumasa; Sugo, Yumi; Kimura, Atsushi; Kurashima, Satoshi; Katsumura, Yosuke
no journal, ,
no abstracts in English
-ray irradiation using a spin-trap CYPMPOOka, Toshitaka; Yamashita, Shinichi; Saiki, Seiichi; Yokoya, Akinari; Katsumura, Yosuke*; Kamibayashi, Masato*
no journal, ,
no abstracts in English
Oshima, Akihiro*; Shiraki, Fumiya*; Takasawa, Yuya*; Fujita, Hajime*; Yoshikawa, Taeko*; Tatsumi, Takahiro*; Tsubokura, Hidehiro*; Takahashi, Tomohiro*; Gowa, Tomoko*; Sakaue, Kazuyuki*; et al.
no journal, ,
no abstracts in English