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Shiraishi, Yuta*; Matsuya, Yusuke; Kusumoto, Tamon*; Fukunaga, Hisanori*
Physics in Medicine & Biology, 69(1), p.015017_1 - 015017_14, 2024/01
Times Cited Count：0 Percentile：0.05(Engineering, Biomedical)FLASH radiotherapy (FLASH-RT) using ultra-high dose rate (
40 Gy/sec) is known as a new treatment which is expected to enable preserving normal tissue functions, compared to the conventional radiotherapy (CONV-RT) with high dose rate (
6 Gy/min). To date, it is believed that the modulation of chemical processes caused by interactions between radiation tracks under FLASH-RT is a key factor in the functional preservation of normal tissues; however, the relationship between changes in chemical processes and cellular responses remains uncertain. In this study, we developed a prediction model (integrated microdosimetric-kinetic (IMK) model for FLASH-RT) taking into account of the relationship between the chemical process and the DNA damage yields (which is the initial response) under ultra-high dose rate irradiation, to investigate the cellular mechanisms. As a result, the developed model considering the chemical-processes dependent change in DNA damage yields successfully reproduced the measured cell-killing effects of both CONV-RT and FLASH-RT for various cell line types. This model development would contribute on not only precisely understanding of cellular mechanisms after FLASH-RT irradiation but also enabling the prediction of therapeutic effects with high precision.
Shiraishi, Fumito*; Chihara, Ryoji*; Tanimoto, Risa*; Tanaka, Kazuya; Takahashi, Yoshio*
Island Arc, 31(1), p.e12448_1 - e12448_9, 2022/05
Times Cited Count：0 Percentile：0(Geosciences, Multidisciplinary)At Yunotaki Fall in north Japan, manganese-oxidizing bacteria were previously assumed to have oxidized manganese to precipitate birnessite, which relied on oxygen released from algae. However, it remained unclear whether larger-scale manganese oxide precipitation was actually occurring under light conditions. This study evaluated the contribution of indirect oxidation using microelectrodes to analyze local water chemistry, in addition to bulk water chemistry and DNA analyses. The results of this study demonstrate that low bulk pH values in the hot spring water hindered indirect oxidation despite the occurrence of active oxygenic photosynthesis and that direct oxidation by manganese-oxidizing bacteria is considered to dominate in the investigated sample.
Suzuki, Ryosuke*; Matsubara, Masaaki*; Sakamoto, Kenji*; Suzuki, Masato*; Shiraishi, Taisuke*; Yanagihara, Seiji*; Izawa, Satoru*; Wakai, Takashi
Experimental Techniques, 40(1), p.253 - 260, 2016/09
Times Cited Count：0 Percentile：0.03(Engineering, Mechanical)The plastic collapse behavior and strength were investigated for an austenitic stainless steel pipe with two 90
through-wall notches perpendicular to the pipe axis direction. Double-notch specimens with various notch separation distances were coated with photo-plastic film. Arbitrary combined axial tensile and bending loads were applied to the specimens. Changes in the photo-plastic fringe pattern were observed during the tests to investigate the plastic collapse behavior. The plastic collapse strength was evaluated using a model based on an elastic-perfectly plastic body. The photo-plastic fringe patterns at the experimental plastic collapse point differed based on the loading history. Thus, the plastic collapse behavior depends on the loading history. In addition, the plastic collapse strength differed based on the loading history and hardly depended on the notch separation distance. The experimental plastic collapse occurred before reaching the theoretical plastic point for only some pure-tension loading tests. Thus, the model analysis based on an elastic-perfectly plastic body used in this study might give an unconservative estimate for the plastic collapse of a stainless steel pipe subjected to a pure tension load.
Hayashi, Nobuhiko; Honda, Mitsuru; Shiraishi, Junya; Miyata, Yoshiaki; Wakatsuki, Takuma; Hoshino, Kazuo; Toma, Mitsunori; Suzuki, Takahiro; Urano, Hajime; Shimizu, Katsuhiro; et al.
Europhysics Conference Abstracts (Internet), 39E, p.P5.145_1 - P5.145_4, 2015/06
Wakatsuki, Takuma; Suzuki, Takahiro; Hayashi, Nobuhiko; Shiraishi, Junya; Ide, Shunsuke; Takase, Yuichi*
Europhysics Conference Abstracts (Internet), 39E, p.P5.144_1 - P5.144_4, 2015/06
Wakatsuki, Takuma; Suzuki, Takahiro; Hayashi, Nobuhiko; Shiraishi, Junya; Ide, Shunsuke; Takase, Yuichi*
Plasma Physics and Controlled Fusion, 57(6), p.065005_1 - 065005_12, 2015/06
Times Cited Count：9 Percentile：41.18(Physics, Fluids & Plasmas)Mimura, Ryuji; Muraguchi, Yoshinori; Nakashio, Nobuyuki; Nemoto, Koichi; Shiraishi, Kunio
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05
The JAERI's Reprocessing Test Facility (JRTF) was the first engineering-scale reprocessing facility constructed in Japan. The JRTF was operated from 1968 to 1969 to reprocess spent fuels from the Japan Research Reactor No.3 (JRR-3). As a result of the operation (total 3 runs) by PUREX process, 200 g of highly purified plutonium (Pu) were extracted. In this operation, about 70 m
of liquid waste was generated and part of this waste, which including Pu, with relatively high radioactivity, was stored in six large tanks. After shutdown of the facility, the JRTF decommissioning program was started in 1990 to develop decommissioning technologies and to obtain experiences and data on dismantling of fuel cycle facilities. Liquid waste in the tanks was treated from 1982 to 1998. Dismantling of tanks started in 2002. The tanks were installed in narrow concrete cells and inside of the cell was high dose area. Dismantling method for the tank is important factor to decide manpower and time for dismantlement. In this paper, in-situ dismantling of the liquid waste storage tank and its preparation work are discussed.
Tachibana, Mitsuo; Kishimoto, Katsumi; Shiraishi, Kunio
International Nuclear Safety Journal (Internet), 3(4), p.16 - 24, 2014/11
Three research reactors were permanently shut down in the Nuclear Science Research Institute (NSRI) of the Japan Atomic Energy Agency (JAEA) as of October 2014. Safe storage or one-piece removal method was applied to decommissioning of these research reactors depending on decommissioning cost and utilization of facilities and so on. Various kinds of data and experiences were obtained through decommissioning of these research reactors. This report shows data and experiences on the research reactors decommissioning in the NSRI of the JAEA.
Shiraishi, Junya; Miyato, Naoaki; Matsunaga, Go; Honda, Mitsuru; Hayashi, Nobuhiko; Ide, Shunsuke
Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 8 Pages, 2014/10
Extension of the kinetic-magnetohydrodynamic (MHD) model is presented to include toroidal rotation shear effect for the first time. The sheared rotation is introduced through generalization of the guiding center Lagrangian, yielding two additional terms in a quadratic form of mode-particle resonance. Additionally, another new term is introduced by using the equilibrium distribution function with rotation effect. These three terms are overlooked in conventional models. The new model is applied to stability analysis of resistive wall modes (RWMs) successfully. Numerical results show that the rotation shear reduces RWM growth rates further, which is consistent with experimental results.
Aiba, Nobuyuki; Hirota, Makoto*; Matsuyama, Akinobu; Shiraishi, Junya; Bierwage, A.
Proceedings of 25th IAEA Fusion Energy Conference (FEC 2014) (CD-ROM), 8 Pages, 2014/10
A mechanism exciting magnetohydrodynamic (MHD) instabilities in rotating tokamak plasmas is found numerically for the first time. This mechanism is the interplay between a resistive wall mode (RWM) and a stable MHD mode. When the plasma has a stable discrete eigenmode, a reversed shear Alfv
n eigenmode (RSAE) for example, a MHD mode is destabilized when plasma equilibrium rotation frequency is similar to the frequency of this stable eigenmode in a static equilibrium. This destabilization is also observed even when the eigenmode couples with Alfvn continua. This result suggests that for steady state high beta tokamaks, like DEMO, it is necessary to shape the safety factor profile in such a way that no stable eigenmode exists in the band of rotation frequency.
Shiraishi, Junya; Aiba, Nobuyuki; Miyato, Naoaki; Yagi, Masatoshi
Nuclear Fusion, 54(8), p.083008_1 - 083008_8, 2014/08
Times Cited Count：10 Percentile：45.44(Physics, Fluids & Plasmas)Toroidal rotation effects are self-consistently taken into account not only in the linear magnetohydrodynamic (MHD) stability analysis but also in the equilibrium calculation. The MHD equilibrium computation is affected by centrifugal force due to the toroidal rotation. To study the toroidal rotation effects on resistive wall modes (RWMs), a new code has been developed. The RWMaC modules, which solve the electromagnetic dynamics in vacuum and the resistive wall, have been implemented in the MINERVA code, which solves the Frieman-Rotenberg equation that describes the linear ideal MHD dynamics in a rotating plasma. It is shown that modification of MHD equilibrium by the centrifugal force significantly reduces growth rates of RWMs. Moreover, it can open a stable window which does not exist under the assumption that the rotation affects only the linear dynamics.
Shiraishi, Junya; Miyato, Naoaki; Matsunaga, Go
Plasma and Fusion Research (Internet), 9, p.3403027_1 - 3403027_4, 2014/04
To investigate the rotation shear effect on the RWM (Resistive Wall Mode) stability, we generalize the formalism of kinetic RWM theory to include a general equilibrium rotation. Starting from the guiding-center Lagrangian with the non-uniform rotation, we generalize the energy functional associated with the drift-kinetic resonance. By the generalized kinetic energy functional, we derive a new dispersion relation in the large aspect ratio limit. Numerical analysis of the new dispersion relation indicates that the rotation shear stabilizes the RWMs as observed in experiments
Shiraishi, Iyo; Suzuki, Masao*; Shikazono, Naoya; Fujii, Kentaro; Yokoya, Akinari
Journal of Radiation Research, 55(Suppl.1), p.i92 - i93, 2014/03
spp. under the ISS environmental conditions for performing exposure experiments of microbes in the Tanpopo missionKawaguchi, Yuko*; Yang, Y.*; Kawashiri, Narutoshi*; Shiraishi, Keisuke*; Takasu, Masako*; Narumi, Issey*; Sato, Katsuya; Hashimoto, Hirofumi*; Nakagawa, Kazumichi*; Tanigawa, Yoshiaki*; et al.
Origins of Life and Evolution of Biospheres, 43(4-5), p.411 - 428, 2013/10
Times Cited Count：41 Percentile：80.34(Biology)Honda, Mitsuru; Shiraishi, Junya; Aiba, Nobuyuki
Purazuma, Kaku Yugo Gakkai-Shi, 89(5), P. 330, 2013/05
no abstracts in English
-type Si at room temperatureShiko, Eiji*; Ando, Kazuya*; Kubo, Kazuki*; Saito, Eiji; Shinjo, Teruya*; Shiraishi, Seiji*
Physical Review Letters, 110(12), p.127201_1 - 127201_5, 2013/03
Times Cited Count：153 Percentile：97.35(Physics, Multidisciplinary)A spin battery concept is applied for the dynamical generation of pure spin current and spin transport in -type silicon (-Si). Ferromagnetic resonance and effective s-d coupling in Ni
Fe
results in spin accumulation at the NiFe/-Si interface, inducing spin injection and the generation of spin current in the -Si. The pure spin current is converted to a charge current by the inverse spin Hall effect of Pd evaporated onto the -Si. This approach demonstrates the generation and transport of pure spin current in -Si at room temperature.
Ide, Shunsuke; Aiba, Nobuyuki; Bolzonella, T.*; Challis, C. D.*; Fujita, Takaaki; Giruzzi, G.*; Joffrin, E.*; Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Honda, Mitsuru; et al.
Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/03
Shiraishi, Junya; Aiba, Nobuyuki; Miyato, Naoaki; Yagi, Masatoshi
Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/03
Effects of plasma toroidal rotation are self-consistently taken into account not only in the magnetohydrodynamic (MHD) stability analysis but also in the equilibrium calculation. To study the effects of toroidal rotation on resistive wall modes (RWMs), a new code has been developed. The RWMaC modules, which solve the electromagnetic dynamics in vacuum and the resistive wall, have been implemented in the MINERVA code, which solves the Frieman-Rotenberg equation that describes the linear ideal MHD in a rotating plasma. It is shown for the first time that MHD equilibrium change induced by toroidal rotation significantly reduces the growth rates of RWMs. Moreover, it can open the stable window which does not exist under the assumption that the rotation affects only the linear dynamics. The rotation modifies the equilibrium pressure, current density, and mass density profiles, which results in the change of the potential energy including rotational effects.
Shiina, Takuya; Watanabe, Ritsuko; Shiraishi, Iyo; Suzuki, Masao*; Sugaya, Yuki; Fujii, Kentaro; Yokoya, Akinari
Radiation and Environmental Biophysics, 52(1), p.99 - 112, 2013/03
Times Cited Count：18 Percentile：59.22(Biology)Aiba, Nobuyuki; Shiraishi, Junya; Hirota, Makoto
Plasma Physics and Controlled Fusion, 55(7), p.074002_1 - 074002_7, 2013/00
Times Cited Count：6 Percentile：26.2(Physics, Fluids & Plasmas)The authors identified that plasma poloidal rotation sometimes plays an important role for ideal MHD stability due to changing the Doppler-shift frequency. As the result, the stability of edge localized MHD mode can depends on the direction of toroidal rotation; this dependence is qualitatively consistent with the experimental results observed in JT-60U. Plasma rotation is also responsible for the stability of resistive wall mode (RWM). In reversed shear plasmas, plasma rotation once stabilize this RWM but destabilize this again when rotation frequency reaches to certain frequency. This re-destabilization is thought to be related to the coupling between RWM and a stable MHD wave; this coupling is one of the destabilizing mechanisms discussed in previous theoretical papers. This re-destabilized RWM can become unstable in the plasma whose beta value is below no-wall beta limit.
