Kumada, Takayuki; Ushida, Takahiro*; Shimizu, Yuta*; Kumagai, Jun*
Radiation Physics and Chemistry, 77(10-12), p.1318 - 1322, 2008/10
Very recently, we succeeded in observing totally more than 50 sharp ESR lines of H and its isotope substituents HD, HD, and HD in -ray irradiated solid para-H (p-H) and p-H-D and p-H-HD mixtures. We also observed isotope-substitution reactions such as H + HD HD + H and H + D HD + H. The H ions diffuse in solid p-H via the repetition of H + H H + H reactions which terminate by the H + HD or H + D reactions. The HD, HD, and HD ions, on the other hand, are immobile in solid p-H. They decay via geminate recombination with trapped electrons within the time-scale of 5 hours.
Kimura, Atsushi; Taguchi, Mitsumasa; Kondo, Takafumi*; Yang, J.*; Yoshida, Yoichi*; Hirota, Koichi
Radiation Physics and Chemistry, 77(10-12), p.1253 - 1257, 2008/10
Adachi, Masahiro; Saito, Yuichi; Chiba, Atsuya; Narumi, Kazumasa; Yamada, Keisuke; Kaneko, Toshiaki*
Radiation Physics and Chemistry, 77(10-12), p.1328 - 1332, 2008/10
no abstracts in English
Kitazawa, Sin-iti; Yamamoto, Shunya; Asano, Masaharu; Saito, Yuichi; Ishiyama, Shintaro
Radiation Physics and Chemistry, 77(10-12), p.1333 - 1336, 2008/10
Radiation-induced luminescence (RIL) was generated using 10-keV N irradiation at room temperature to study energy transfer in TiO targets produced by sol-gel and direct-oxidation methods. The RIL spectra in the UV-visible region exhibited numerous atomic lines and three humps; they were deconvolved and proved to be visible bands at 617 and 479 nm from crystalline defects and a UV band at 320 nm from electron transitions between the Ti 3d and O 2s states in the TiO crystal.
Yokoya, Akinari; Shikazono, Naoya; Fujii, Kentaro; Urushibara, Ayumi; Akamatsu, Ken; Watanabe, Ritsuko
Radiation Physics and Chemistry, 77(10-12), p.1280 - 1285, 2008/10
Ionizing radiation induces a variety of damages in cellular DNA, which is thought to be the critical target of biological effects of radiation, by both direct energy deposition on DNA (direct effect) and reactions with diffusible water radicals (indirect effect). One of the goals of our study is to clarify the nature of DNA damage induced by direct effect. The yields of single- and double-strand breaks, base lesions and clustered damage induced in a plasmid DNA were measured after exposing to various kinds of radiation (ion particles; 20 to 500 keV/ , photons; 0.4 keV to 1.3 MeV). Base excision repair enzymes were used to detect the oxidative base lesions. In order to obtain more detailed insights into the physicochemical mechanism of DNA damage induction, short-lived base radicals by applying an EPR spectrometer at a synchrotron ultrasoft X-ray beamline. Experimental evidences obtained by these methods will be discussed in comparison with the previous plasmid data.
Asano, Akira*; Yang, J.*; Kondo, Takafumi*; Norizawa, Kimihiro*; Nagaishi, Ryuji; Takahashi, Kenji*; Yoshida, Yoichi*
Radiation Physics and Chemistry, 77(10-12), p.1244 - 1247, 2008/10
The molar extinction coefficient and the radiolytic yield of solvated electrons in ionic liquid of DEMMA-TFSI were estimated respectively to be 2.310 L mol cm and 0.810 mol J by observing the reaction and kinetics of solvated electron and dry electron in the ionic liquid. The solvated electron in DEMMA-TFSI has a very broad absorption spectrum peaking at 1100 nm and reacts slowly with pyrene with a rate constant of 3.510 L mol s, while the dry electron is captured rapidly by pyrene with C value of 0.065 mol L.
Yang, J.*; Kondo, Takafumi*; Norizawa, Kimihiro*; Nagaishi, Ryuji; Taguchi, Mitsumasa; Takahashi, Kenji*; Kato, Ryuji*; Anishchik, S. V.*; Yoshida, Yoichi*; Tagawa, Seiichi*
Radiation Physics and Chemistry, 77(10-12), p.1233 - 1238, 2008/10
First observation of picosecond dynamics in ionic liquid of DEMMA-TFSI in radiation chemistry was reported. It is found that the electron produced by ionization is solvated to full solvation in ionic liquid with a rate constant of 3.910 s. The yield of solvated electrons in picosecond time region is 1.210 mol J. The dry electron in ionic liquid reacts rapidly with biphenyl and pyrene with a rate constant of 3.8 to 7.910 L mol s. The geminate ion recombination in n-dodecane and n-hexane was also observed by monitoring the transient absorptions at 523 nm.
Ukai, Masatoshi*; Yokoya, Akinari; Fujii, Kentaro; Saito, Yuji
Radiation Physics and Chemistry, 77(10-12), p.1265 - 1269, 2008/10
In order to substantiate the hydrated structure of DNA from the view point of the electronic properties, we develop a new spectroscopic technique for the photoelectrons ejected from solutions dissolving biological molecules using a soft X-ray synchrotron radiation (SPring-8, BL23SU) in combination with liquid jet technique in vacuum. In this paper, we present the first evidence of the spectrum of total photoelectron yields for a nucleotide, guanosine-5'-monophosphate, in solution in the energy region of so-called water window around nitrogen K-edge. A liquid nucleotide/water sample is maintained in the form of continuous thin water jet (diameter 20 m) in vacuum and is intersected by a highly focused soft X-ray beam. The obtained spectrum in solution shows common features with the spectrum in solid film. Nitrogen atoms only exist in the base site, so that the spectral similarities can be explained by the hydrophobic property of the base site.
Nikjoo, H.*; Emifietzoglou, D.*; Watanabe, Ritsuko; Uehara, Shuzo*
Radiation Physics and Chemistry, 77(10-12), p.1270 - 1279, 2008/10
Microdosimetry and track structure have been applied to scrutinize and understand aspects of radiation damage in biological molecules from a theoretical approach. To this end track structure has provided a basis for understanding the mechanism(s) that shape dose-effect relationships. There is a wealth of information and data accumulated from radiation biology that need to be placed in the framework of a general descriptive theory. While there are many classical radiobiology questions remain unanswered new ideas and challenging question are emerging. Among many, simulation of radiation track at molecular level is an emerging tool in radiobiology and theoretical radiotherapy. In this paper we present recent progress in development of low energy electron tracks in condensed media and high energy proton tracks and discuss progress in characterizing DNA damage in terms of types and complexity.
Kumagai, Yuta; Lin, M.; Lampre, I.*; Mostafavi, M.*; Muroya, Yusa*; Katsumura, Yosuke
Radiation Physics and Chemistry, 77(10-12), p.1198 - 1202, 2008/10
The absorption spectra of the hydrated electron in concentrated LiCl, LiClO, LiSO, MgCl and Mg(ClO) deuterated water solutions were measured by pulse radiolysis techniques from room temperature to 300 C at a constant pressure of 25 MPa. As salt effects, shifts to shorter wavelengths and broadening of the absorption band of the solvated electron were observed at room temperature. At elevated temperatures, similar spectral shifts were observed. The broadening of the spectrum, on the other hand, becomes smaller with increasing temperature. These result indicate that high concentration of salts not only form an ion atmosphere to cause the spectral shifts, but also affect the solvation structure of an electron. The smaller broadening at elevated temperatures suggest that a decrease in the density expand the distance between solvated electron and surrounding ions, and that therefore the effect on the solvation structure becomes smaller.
Lin, M.; Katsumura, Yosuke; Muroya, Yusa*; He, H.*; Miyazaki, Toyoaki*; Hiroishi, Daisuke*
Radiation Physics and Chemistry, 77(10-12), p.1208 - 1212, 2008/10
Sodium formate neutral aqueous solutions saturated with NO were studied by pulse radiolysis techniques from room temperature to 400 C. The absorption spectra of CO show a red shift from = 235 nm at 25 C to 280 nm at 400 C. The second-order decay of CO is not monotonically temperature-dependent: the rate constant (2/) slightly increases with temperature up to 200 C, then decreases to a valley at 300 C, and it sharply increases again for temperature 350 C. (CO) increases with temperature from room temperature to 400 C. Significant density effect on (CO) is found at 400 C. Assumed (CO) is independent on temperature, at 400 C, the density dependence of (CO) in the presence of NO agrees well with that of [(e)+(H)+(OH)].
Fu, H.*; Katsumura, Yosuke; Lin, M.; Muroya, Yusa*
Radiation Physics and Chemistry, 77(10-12), p.1300 - 1305, 2008/10
In the present work, laser photolysis techniques have been used to study the transient species of silybin (abbreviated as SLB) in ethanol solutions. It has been demonstrated that the exposure of silybin to 248 nm excimer laser gives rise to monophotonic ionization with a high quantum yield. The transient species have been identified, and a series of related kinetics parameters have also been obtained. For the sake of comparison, we approached the problem using another way to reduce silybin, i.e. attack of solvated electrons, e, produced in pulse radiolysis. The rate constant for reaction of e was determined to be 3.810 dmmols at 720 nm, which is consistent with 4.610 dmmols, obtained by laser photolysis.
Muroya, Yusa*; Lin, M.; Han, Z.*; Kumagai, Yuta; Sakumi, Akira*; Ueda, Toru*; Katsumura, Yosuke
Radiation Physics and Chemistry, 77(10-12), p.1176 - 1182, 2008/10
In order to study radiation-induced fast phenomena, a new pulse radiolysis system with higher time resolution based on pulse-and-probe method was developed and utilized for practical work. A few picosecond electron beam generated from a linear accelerator, in which a laser photocathode RF-gun is introduced, was synchronized with a femtosecond laser pulse which is employed as the analyzing light. The synchronization precision between them was suppressed within 1.6 ps (rms). Converting the fundamental laser into white light continuum or optical parametric amplification allows to measure in the wide wavelength from visible to infrared region.
Katsumura, Yosuke; Lin, M.; Yokoya, Akinari; Hatano, Yoshihiko
Radiation Physics and Chemistry, 77(10-12), P. 1119, 2008/10
As Guest Editors, we publish a special issue of Radiation Physics and Chemistry in conjunction with the ASR2007 Symposium, an international symposium on "Charged Particle and Photon Interactions with Matter" held on November 6-9, 2007 at the Advanced Science Research Center (ASRC), Japan Atomic Energy Agency (JAEA) in Tokai.
Enomoto, Kazuyuki; Takahashi, Shuichi; Maekawa, Yasunari
no journal, ,
The polymer electrolyte membranes consisting grafted sulfoalkyl ether on ETFE film were prepared. Grafting of vinyl acetate into the irradiated ETFE was carried out under Ar at 40 C. The grafting degrees increased with increasing an irradiation dose. The basic hydrolysis of poly(vinyl acetate) units in the grafting chain led to poly(vinyl alcohol) (PVA) in good yields. The sulfoalkylation of the hydroxyl group in the grafted PVA with 1,3-propanesultone was performed. A ring-opening reaction of 1,3-sultone induced by the nucleophilic addition of PVA gives sulfoalkyl ether in 70% yield. The ATR-IR spectrum of the membrane shows new peaks at 3369, 1647, and 1032 cm, which are assigned to sulfoalkyl ether. The SEM-EDS image of the membrane shows a homogenous distribution of S atoms. The ion exchange capacity and proton conductivity of the membrane are estimated to be 1.6 mequiv g and 0.12 S cm, which are high enough for a fuel cell application.
no journal, ,
no abstracts in English
Nakagawa, Seiko*; Taguchi, Mitsumasa; Ota, Nobuaki*; Hirota, Koichi
no journal, ,
no abstracts in English
no journal, ,
High energy positrons will transfer their energy to molecules on their tracks in insulators as high energy electrons do. Positrons in condensed matter annihilate with electrons by a lifetime of 0.1-10ns. Almost all of positrons are thermalized first. At the end of the positron track, there are many excess electrons and cations formed in the terminal spur. Geminate recombination of dry electrons and cations occur within about 1ps. The positron also has a chance to combine with one of the excess electrons to form a positronium(Ps). Reaction rate of Ps formation is probably close to that of the geminate recombination. These fast reactions are very important because the yield of products shall be controlled by these reactions. Only fast reactions can affect the Ps formation, because the lifetime of free positrons in molecular liquids or solids is about 400ps. I am introducing positron researches that are probably interesting for radiation chemistry.
Sugo, Yumi; Sasaki, Yuji; Taguchi, Mitsumasa; Nagaishi, Ryuji; Kimura, Takaumi
no journal, ,
no abstracts in English
Akamatsu, Ken; Fujii, Kentaro; Yokoya, Akinari; Wada, Seiichi*; Kobayashi, Yasuhiko
no journal, ,
High-dense radical field formed by high- LET radiations and short track electrons emitted from DNA constituent atoms by ultrasoft X- (USX-) irradiation have been suggested to produce severe DNA damage. The aim of this study is to clarify the difference of DNA damage induced by 4He ion beam and USX from that by Co-60 -rays. We have recently attended to unaltered base release, strand break terminus and base lesion, focusing on the effect of nitrogen and oxygen K-shell electron ionization in the USX experiments. The yields of unaltered bases released were determined by HPLC. To quantify and characterize the strand break termini, the digestion rates of the irradiated DNA pretreated with or without calf intestinal alkaline phosphatase by snake venom phosphodiesterase (SVPD) were measured.