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Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke*; Hirata, Yuho; Tsuchida, Hidetsugu*; Yokoya, Akinari*
Journal of Chemical Physics, 162(15), p.154102_1 - 154102_11, 2025/04
Times Cited Count：0 Percentile：0.00(Chemistry, Physical)Scientific knowledge of low-energy electrons resulting from water radiolysis is required to estimate radiation DNA damage. However, since the analysis of water radiolysis is very complex, this study focuses on the experimental values of low-energy electrons related to simple water photolysis and those generated by photoirradiation of electrodes in water. Both experimental analyses involve the presence or absence of a Coulomb field in the parent ion. In this study, we analyzed these experimental values using a calculation code that combines Monte Carlo and molecular dynamics methods. As a result, it was shown that the code reproduced the experimental values even under different experimental conditions, and the code was validated. The calculation code will be a powerful tool for analyzing the interaction between low-energy electrons and DNA, and is expected to be applied to elucidate the formation mechanism of radiation DNA damage.
Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke*; Hirata, Yuho; Tsuchida, Hidetsugu*; Ito, Yuma*; Yokoya, Akinari*
Communications Chemistry (Internet), 8, p.60_1 - 60_9, 2025/03
Times Cited Count：1 Percentile：77.31(Chemistry, Multidisciplinary)Radiation DNA damage is formed from direct and indirect effects. The direct effect is the interaction between DNA and a radiation, while the indirect effect is the chemical reaction between DNA and radiolytic chemical species. We believed that when the direct effect is induced, multiple lesions are formed within 10 base pairs (about 3.4 nm) of DNA. The damage reduces repair efficiency and induces biological effects. In this study, DNA damage induced by only indirect effects was quantitatively evaluated. Our results indicated that the multiple damage is formed when only 10s of eV energy is deposited to water in the vicinity of DNA, although its formation probability is less than 1%. In other words, the possibility of late biological effects cannot be excluded simply by imparting energy to water in the extreme vicinity of DNA without direct interaction between radiation and DNA. Our results are one of the most important findings for understanding low-dose radiation risk.
Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke*; Hirata, Yuho; Tezuka, Tomoya*; Tsuchida, Hidetsugu*; Yokoya, Akinari*
Scientific Reports (Internet), 14, p.24722_1 - 24722_15, 2024/10
Times Cited Count：2 Percentile：58.46(Multidisciplinary Sciences)Scientific insight of water radiolysis is essential to estimate the direct and indirect effects of radiation DNA damage. Secondary electrons produced by water radiolysis are responsible for both effects. Here, we use a first-principles code to calculate the femtosecond dynamics of secondary electrons produced as a result of 20-30 eV energy deposition to water and analyze the formation mechanism of radiolytic chemical species produced in a nano-size ultra-small space region. From the results, it was clarified that the chemical species produced by water radiolysis begin to densify in the ultra-small region of a few nanometers when the deposition energy exceeds 25 eV. Our results provide important scientific insights into the formation of clustered DNA damage, which is believed to cause biological effects such as cell death.
Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke; Hirata, Yuho; Tezuka, Tomoya*; Tsuchida, Hidetsugu*; Yokoya, Akinari*
RSC Advances (Internet), 13(46), p.32371 - 32380, 2023/11
Times Cited Count：4 Percentile：39.53(Chemistry, Multidisciplinary)Although scientific knowledge of photolysis and radiolysis of water is widely used in the life sciences and other fields, the formation mechanism of the spatial distribution of hydrated electrons (spur) resulting from energy deposition to water is still not well understood. The chemical reaction times of hydrated electrons, OH radicals, and H
O
in the spur strongly depend on the spur radius. In our previous study, we elucidated the mechanism at a specific given energy (12.4 eV) by first-principles calculations. In the present study, we performed first-principles calculations of the spur radius at the deposition energies of 11-19 eV. The calculated spur radius is 3-10 nm, which is consistent with the experimental prediction (~4 nm) for the energy range of 8-12.4 eV, and the spur radius gradually increases with increasing energy. The spur radius is a new scientific knowledge and is expected to be widely used for estimating radiation DNA damage.
Kai, Takeshi; Toigawa, Tomohiro; Matsuya, Yusuke*; Hirata, Yuho; Tezuka, Tomoya*; Tsuchida, Hidetsugu*; Yokoya, Akinari*
RSC Advances (Internet), 13(11), p.7076 - 7086, 2023/03
Times Cited Count：10 Percentile：64.35(Chemistry, Multidisciplinary)Scientific insights of water radiolysis are widely used in the life sciences and so on, however, the formation mechanism of radicals, a product of water radiolysis, is still not well understood. We are challenging to develop a simulation code to solve this formation mechanism from the viewpoint of radiation physics. Our first-principles calculations have revealed that the behavior of secondary electrons in water is governed not only by collisional effects but also by polarization effects. Furthermore, from the predicted ratio of ionization to electronic excitation, based on the spatial distribution of secondary electrons, we successfully reproduce the initial yield of hydrated electrons predicted in terms of radiation chemistry. The code provides us a reasonable spatiotemporal connection from radiation physics to radiation chemistry. Our findings are expected to provide newly scientific insights for understanding the earliest stages of water radiolysis.
Hosoya, Yoshihiro*; Matsumura, Yuta*; Tomota, Yo*; Onuki, Yusuke*; Harjo, S.
ISIJ International, 60(9), p.2097 - 2106, 2020/09
Times Cited Count：9 Percentile：36.86(Metallurgy & Metallurgical Engineering)Hosoya, Yoshihiro*; Matsumura, Yuta*; Tomota, Yo*; Onuki, Yusuke*; Harjo, S.
Tetsu To Hagane, 106(3), p.154 - 164, 2020/03
Times Cited Count：3 Percentile：12.45(Metallurgy & Metallurgical Engineering)Iwata, Keiji*; Imafuku, Muneyuki*; Suzuki, Kanki*; Shobu, Takahisa; Orihara, Hideto*; Sakai, Yusuke*; Akita, Koichi; Oya, Shinichi*; Ishiyama, Kazushi*
Journal of Applied Physics, 117(17), p.17A910_1 - 17A910_4, 2015/03
Times Cited Count：8 Percentile：31.50(Physics, Applied)Internal stress distribution for generating closure domains occurring in laser-irradiated Fe-3%Si(110) steels was investigated using high-energy X-ray analysis and domain theory based on the variational principle. The measured triaxial stresses inside the specimen were compressive and the stress in the rolling direction became more dominant than stresses in the other directions. The calculations based on the variational principle of magnetic energy for closure domains showed that the measured triaxial stresses made the closure domains more stable than the basic domain without closure domains. The experimental and calculation results reveal that the laser-introduced internal stresses result in the occurrence of the closure domains.
and reference compound ThCd; Studied by the de Haas-van Alphen effectHirose, Yusuke*; Miura, Yasunao*; Tsutsumi, Hiroki*; Yoshiuchi, Shingo*; Oya, Masahiro*; Sugiyama, Kiyohiro*; Takeuchi, Tetsuya*; Yamagami, Hiroshi*; Yamamoto, Etsuji; Haga, Yoshinori; et al.
Physica Status Solidi (B), 250(3), p.642 - 645, 2013/03
Times Cited Count：4 Percentile：18.66(Physics, Condensed Matter)
Si and YbTZn
(T: Co, Rh, Ir)Onuki, Yoshichika; Yasui, Shinichi*; Matsushita, Masaki*; Yoshiuchi, Shingo*; Oya, Masahiro*; Hirose, Yusuke*; Dung, N. D.*; Honda, Fuminori*; Takeuchi, Tetsuya*; Settai, Rikio*; et al.
Journal of the Physical Society of Japan, 80(Suppl.A), p.SA003_1 - SA003_6, 2011/12
ZnOnuki, Yoshichika; Yasui, Shinichi*; Yoshiuchi, Shingo*; Oya, Masahiro*; Matsushita, Masaki*; Hirose, Yusuke*; Takeuchi, Tetsuya*; Honda, Fuminori*; Settai, Rikio*; Sugiyama, Kiyohiro*; et al.
Journal of Physics; Conference Series, 273, p.012013_1 - 012013_4, 2011/02
Times Cited Count：1 Percentile：32.13(Physics, Condensed Matter)ZnTakeuchi, Tetsuya*; Yasui, Shinichi*; Toda, Masatoshi*; Matsushita, Masaki*; Yoshiuchi, Shingo*; Oya, Masahiro*; Katayama, Keisuke*; Hirose, Yusuke*; Yoshitani, Naohisa*; Honda, Fuminori*; et al.
Journal of the Physical Society of Japan, 79(6), p.064609_1 - 064609_15, 2010/06
Times Cited Count：43 Percentile：82.95(Physics, Multidisciplinary)ZnYoshiuchi, Shingo*; Toda, Masatoshi*; Matsushita, Masaki*; Yasui, Shinichi*; Hirose, Yusuke*; Oya, Masahiro*; Katayama, Keisuke*; Honda, Fuminori*; Sugiyama, Kiyohiro*; Hagiwara, Masayuki*; et al.
Journal of the Physical Society of Japan, 78(12), p.123711_1 - 123711_4, 2009/12
Times Cited Count：41 Percentile：82.54(Physics, Multidisciplinary)
-edgeUkai, Masatoshi*; Yokoya, Akinari; Nonaka, Yusuke*; Fujii, Kentaro; Saito, Yuji
Radiation Physics and Chemistry, 78(12), p.1202 - 1206, 2009/12
Times Cited Count：6 Percentile：39.36(Chemistry, Physical)To substantiate the hydrated structure of DNA from the view point of the electronic properties, we developed a new spectroscopic technique of photoelectrons ejected from solutions dissolving biological molecules using soft X-ray synchrotron radiation in combination with liquid jet in vacuum. The experiments are carried out at the BL23SU in SPring-8, Japan. The liquid sample is maintained in the form of continuous micro-beam (
= 20 
m) in vacuum and is intersected by a well focused nearly micro-beam of synchrotron-radiation of less than 50 m. In this paper, we present (1) the partial yields of photoelectrons for liquid water molecules and oxygen Auger electron spectra in the energy range around the oxygen K-edge, and (2) the total photoelectron yields for DNA nucleotides (AMP, CMP, and GMP) in water solutions near nitrogen K-edge, which correspond to the X-ray absorption spectra (XANES).
Sakasai, Akira; Ishida, Shinichi; Matsukawa, Makoto; Akino, Noboru; Ando, Toshinari*; Arai, Takashi; Ezato, Koichiro; Hamada, Kazuya; Ichige, Hisashi; Isono, Takaaki; et al.
Nuclear Fusion, 44(2), p.329 - 334, 2004/02
no abstracts in English
Sakasai, Akira; Ishida, Shinichi; Matsukawa, Makoto; Akino, Noboru; Ando, Toshinari*; Arai, Takashi; Ezato, Koichiro; Hamada, Kazuya; Ichige, Hisashi; Isono, Takaaki; et al.
Nuclear Fusion, 44(2), p.329 - 334, 2004/02
Times Cited Count：7 Percentile：22.24(Physics, Fluids & Plasmas)no abstracts in English
Kamiya, Junichiro; Noshiroya, Shiyoji; Namekawa, Yuya; Hikichi, Yusuke; Sato, Atsushi; Kinsho, Michikazu; Yanagibashi, Toru*
no journal, ,
The 3 GeV synchrotron (Rapid Cycling Synchrotron: RCS) in J-PARC facility is one of the highest proton beam power accelerators, aiming 1 MW beam power. The RCS was completed in 2007. Since then, the vacuum system of the RCS has been stably operated through the steady/non-steady maintenances and the additional upgrades. This report aims to introduce the upgrade in the RCS vacuum system and the vacuum status of the beam line during the accelerator operation period.
Sakai, Yusuke*; Akita, Koichi*; Oya, Shinichi*; Sueyoshi, Kazuyuki*; Shobu, Takahisa; Imafuku, Muneyuki*; Suzuki, Kanki*; Iwata, Keiji*
no journal, ,
no abstracts in English
Kobayashi, Kazuhiro; Hayashi, Takumi; Nishikawa, Yusuke*; Oya, Yasuhisa*; Yamanishi, Toshihiko; Okuno, Kenji*
no journal, ,
no abstracts in English
Takubo, Yusaku*; Takayama, Yusuke; Idiart, A.*; Toya, Naruhisa*; Ishida, Keisuke*; Fujisaki, Kiyoshi*
no journal, ,
Coupled THC analysis below 100 degrees was performed for existing studies (laboratory tests and Full-scale Engineered Barriers Experiment (FEBEX) in-situ tests) using PFLOTRAN, which has been applied as a TH/THC coupled analysis code. By comparing the results of each test measurement and analysis, input parameters that are considered to have a significant impact on the analysis result of the chemical field were investigated.
