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Kumagai, Yuta; Nagaishi, Ryuji; Yamada, Reiji; Muroya, Yusa*; Katsumura, Yosuke
no journal, ,
Coexistence effect of colloidal silica on the radiation-induced reactions was studied by 
- and pulse radiolysis technique. First, reduction yields of metal ions in acidic aqueous solutions of colloidal silica were measured by radiolysis experiment. The yields slightly decrease with increasing amount of colloidal silica. From this result, primary yields of reactive species are unlikely to increase by addition of silica. Then reactivity of colloidal silica toward products of water radiolysis was studied by pulse radiolysis experiment. In sodium bicarbonate solution, the yield of carbonate radical formed by reaction of OH radical with bicarbonate ion was measured to decrease in the presence of colloidal silica. This result indicates a competitive reaction between colloidal silica and bicarbonate ion with OH radical, and the reactivity of colloidal silica toward OH radical.
Kumada, Takayuki; Noda, Yohei; Hashimoto, Takeji; Koizumi, Satoshi
no journal, ,
We plan to study structures of spur, blob, and shorttrack using dynamic nuclear polarization (DNP) and small-angle neutron scattering (SANS) methods. Recently, we measured SANS profiles of proton-spin polarized polyethylenes. We found clear evidence that polarization of crystalline part of polyethylene in which paramagnetic species of TEMPO were not doped was smaller than that in amorphous part. This result indicates that DNP is useful to make gradient of spin polarization which can be measured by SANS.
Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao; Muroya, Yusa*; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
no abstracts in English
Saiki, Seiichi; Nagasawa, Naotsugu; Hiroki, Akihiro; Morishita, Norio; Tamada, Masao; Muroya, Yusa*; Kudo, Hisaaki*; Katsumura, Yosuke*
no journal, ,
no abstracts in English
Yamashita, Shinichi; Katsumura, Yosuke; Maeyama, Takuya*; Murakami, Takeshi*; Meesungnoen, J.*; Jay-Gerin, J.-P.*
no journal, ,
Primary yields in water radiolysis with relativistic heavy ions from Heavy Ion Medical Accelerator in Chiba (HIMAC) of National Institute of Radiological Sciences (NIRS) have been measured covering wide range of beam conditions. Experimental results were summarized and compared with results obtained not only in a deterministic simulation but also in a stochastic one. Heavy-ion track structure was discussed from microscopic viewpoints based on the experimental and simulation results.
OH yield near the Bragg peakMaeyama, Takuya*; Yamashita, Shinichi; Katsumura, Yosuke; Baldacchino, G.*; Taguchi, Mitsumasa; Kimura, Atsushi; Murakami, Takeshi*
no journal, ,
Aqueous solution of Coumarin-3-carboxylic acid (CCA) has been applied to yield measurement of OH in water. Production yield of a fluorescent probe, 7OH-CCA, which is a stable product produced after scavenging reaction for OH by CCA, was determined by using HPLC connected to a fluorometer. Taking sensitiveness of fluorometry as an advantage, OH yields near the Bragg peaks, which are known very small compared to those in plateau LET region, have been measured. Contribution of fragmentations, which are known to be significant near the Bragg peaks of high-energy heavy ions, is also being discussed.
Hirade, Tetsuya; Lee, J.*; Nakamura, Takemi
no journal, ,
Stepanov et al. suggested that there are some reactions of ortho-positronium with some reactants, such as the spin-conversion with hydrated electrons and OH radicals. If there is a spin-conversion between ortho-positronium and para-positronium, it is probably possible to detect with the positron annihilation Age-Momentum Correlation measurement (AMOC). We have successfully obtained an experimental result that shows existence of the spin conversion reactions.
Nagaishi, Ryuji; Yamada, Reiji; Sato, Hideo; Kurosawa, Akira; Watahiki, Masaru; Hiyama, Toshiaki
no journal, ,
Radioactive glass wastes, which emit ionizing radiations and heats, are discharged from nuclear power reactor, and are now kept air-cooling at the stage of interim storage. They are expected to be utilized as useful materials or energy resources in the future. In the present study, radiation-induced reactions were investigated by using the analytical pieces of glass wastes at Tokai Reprocessing Plant (TRP), JAEA. Influences of or beta rays on reactions of metal ions in aqueous solution were measured, and the feasibility of wastes as a radiation source was also discussed.
-Al
O
under electron beam irradiationHakoda, Teruyuki; Matsumoto, Kanae*; Mizuno, Akira*; Hirota, Koichi
no journal, ,
no abstracts in English
CLin, M.; Jay-Gerin, J.-P.*; Katsumura, Yosuke; Muroya, Yusa*; Meesungnoen, J.*; Yamashita, Shinichi
no journal, ,
In this work, we measure the density dependent absorption spectra of hydrated electron in DO at 380, 390, and 400 C, and then compare with the literature data for subcritical water. The results show that at a fixed pressure (25 MPa), 
-
decreases monotonically with increasing temperature in passing through the liquid-supercritical water (SCW) phase transition at 
. By contrast, at a fixed density (0.2 and 0.65 g/cm
), - exhibits a minimum near . These behaviours are explained in terms of local density and configurational fluctuations of water structure in SCW.
Lin, M.; Katsumura, Yosuke; Fu, H.*; Yan, Y.*; Muroya, Yusa*; Yamashita, Shinichi
no journal, ,
The temperature dependent behaviors of the absorption spectrum of solvated electron in glycerol were studied from room temperature to 250 C by pulse radiolysis techniques. With a revisit of the absorption coefficient, the time dependent yield of solvated electron in glycerol, from picosecond to microsecond, was also investigated.
Takahashi, Hiroyuki*; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Kumagai, Yuta; Kudo, Hisaaki*
no journal, ,
It was purposed in this work to determine acid dissociation constant of hydroxyl radical (OH) at elevated temperatures because the acido-basic equilibrium reaction, OH 
H
+ O
, is one of the most important reactions in water radiolysis and such information is of crucial importance in management of water coolant in water-cooled nuclear reactors. Benzoic acid, one of typical aromatic compounds, was used as scavenges not only toward OH but also toward O. Pulse radiolysis technique was applied to determine rate constants of the scavenging reactions as well as to observe transient spectra of products in the scavenging reactions. In addition, it was also tried to estimate the p
value at elevated temperatures.
Fu, H.*; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Hata, Kuniki; Fujii, Kentaro; Yokoya, Akinari
no journal, ,
The transient spectral properties and rate constants of the free radical scavenger carnosine reacting with various one-electron oxidants such as OH, Br, N, and CClOO have been studied by pulse radiolysis techniques. Carnosine and its related compounds (CRC) also offer protection to plasmid DNA against X-ray radiation induced damages. Our data demonstrated that carnosine and CRC may play an important role in the maintenance of the antioxidant system.
Fujii, Kentaro; Yokoya, Akinari; Shikazono, Naoya
no journal, ,
To investigate the K-shell photoabsorption effect (photoelectric effect and subsequent secondary electron effect) of DNA damage, dry plasmid DNA (pUC18) films were irradiated with synchrotron monochromatic soft X-rays (270, 435, 560, and 760 eV). Irradiated plasmid DNA was analyzed by agarose gel electrophoresis and the yields of strand breaks were determined by measuring the band intensity of the separated closed circular, open circular and linear forms of the plasmid DNA. The yields of base lesions were determined by the post-irradiation-treatment of the DNA with enzymatic probes (Fpg and Nth) which excise base lesionand visualized it as a strand break. The obtained yields of single strand break (SSB) and the base lesions revealed by enzymatic sensitive sites (ESS) of Fpg and Nth showed the characteristic dependence for photon energy. This result indicates that DNA lesions are induced through varieties of reaction pathways after core-electron ionizations.
Asano, Masaharu; Kimura, Yosuke*; Chen, J.; Maekawa, Yasunari; Yoshida, Masaru
no journal, ,
no abstracts in English
Lin, M.; Muroya, Yusa*; Han, Z.*; Yamashita, Shinichi; Sakumi, Akira*; Ueda, Toru*; Katsumura, Yosuke
no journal, ,
An ultra-fast pulse radiolysis system based on pulse-and-probe method has been developed. The system consists of a 22-MeV S-band electron linac and a femtosecond Ti:Sapphire laser. Being the fs fundamental laser (795 nm) split into two, half of the laser beam is injected into the laser photocathode RF-gun to generate electron beam after converted into third harmonics (265 nm), and the other half is used as a probe laser. Since the wavelength of the probe light can be converted into variable wavelengths (535-2600 nm) by an optical parametric amplifier (TOPAS, Light Conversion Co. Ltd), transient absorption spectroscopy in wide wavelength range can be performed efficiently. Recently, the laser photocathode has been improved by replacing Mg by CsTe. Owing to high quantum efficiency of CsTe, better beam quality was realized such as 
2 nC in charge per pulse, 2 ps in beam width (FWHM) and 3 mm in diameter of full beam size. This system has been utilized to study initial yields and transient behaviors of presolvated and solvated electrons in water and various alcohols.
Ito, Kenji*; Oka, Toshitaka*; Kobayashi, Yoshinori*; Shirai, Yasuharu*; Wada, Kenichiro*; Matsumoto, Masataka*; Fujinami, Masanori*; Hirade, Tetsuya; Honda, Yoshihide*; Hosomi, Hiroyuki*; et al.
no journal, ,
An interlaboratory comparison for positron annihilation lifetime measurements for pure nickel, polycarbonate (PC) and fused silica was performed. Based on the reported data of positron (for nickel) and positronium (for PC and fused silica) components, the uncertainties in the PAL measurements were estimated and their possible source was discussed.
-radiolysis of aqueous sulfuric acid solutions containing oxide powderYamada, Reiji; Kumagai, Yuta; Nagaishi, Ryuji
no journal, ,
H gas released by -ray irradiation to the gas phase of samples of aqueous sulfuric acid solutions containing various alumina and zirconia powders was measured with gas chromatography. The experimental revealed that the amounts of H gas released depended on both solid structures and surface areas of oxide powders.
Park, J.*; Enomoto, Kazuyuki; Yamashita, Takashi*; Maekawa, Yasunari
no journal, ,
We prepared the polymer electrolyte membranes (PEMs) consisting of poly(styrenesulfonic acid) graft chains onto alicyclic polyimide (PI) films using radiation induced-graft polymerization and subsequent sulfonation with a chloro-sulfonic acid solution. The graft polymerization were proceeded with grafting degrees of 0
70%. Sulfonation degrees gradually increased and reached at near a quantitative yeild, indicating the selective sulfonation to the polystyrene graft chains. The PI-based PEMs showed the highest proton conductivity of 0.26 S/cm with water uptake lower than 100%. We could clearly demonstrate that a series of sulfonated polyimide ionomers for PEMs can be synthesized by radiation-graft polymerization of alicyclic polyimide.
Taguchi, Mitsumasa; Kurashima, Satoshi; Baldacchino, G.*; Sugo, Yumi; Kimura, Atsushi; Hirota, Koichi; Katsumura, Yosuke*
no journal, ,
no abstracts in English
Hata, Kuniki; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*; Fu, H.*; Yamashita, Shinichi; Kudo, Hisaaki*; Nakagawa, Keiichi*; Nakagawa, Hidehiko*
no journal, ,
Edaravone and its derivatives are good radical scavengers and expected as a potent radioprotector. In this study, their OH scavenging reactivity was measured by pulse radiolysis technique, and all derivatives showed high reactivity with OH. As a result of measuring rate constants by using competition methods by DMPO, it was shown that there was interaction between derivatives including pyridine ring and DMPO.