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Onishi, Kentaro*; Kobayashi, Takuma*; Mizobata, Hidetoshi*; Nozaki, Mikito*; Yoshigoe, Akitaka; Shimura, Takayoshi*; Watanabe, Heiji*
Japanese Journal of Applied Physics, 62(5), p.050903_1 - 050903_4, 2023/05
Times Cited Count:2 Percentile:71.03(Physics, Applied)While the formation of an GaO interlayer is key to achieving SiO/GaN interfaces with low defect density, it can affect the reliability and stability of metal-oxide-semiconductor (MOS) devices if the annealing conditions are not properly designed. In the present study, we aimed to minimize the growth of the GaO layer on the basis of the sputter deposition of SiO on GaN. Synchrotron radiation X-ray photoelectron spectrometry measurements confirmed the suppressed growth of the GaO layer compared with a SiO/GaN structure formed by plasma-enhanced chemical vapor deposition. Negligible GaO growth was also observed when subsequent oxygen annealing up to 600C was performed. A MOS device with negligible capacitance-voltage hysteresis, nearly ideal flat-band voltage, and low leakage current was demonstrated by performing oxygen and forming gas annealing at temperatures of 600C and 400C, respectively.
Watanabe, Jin*; Araki, Yasufumi; Kobayashi, Koji*; Ozawa, Akihiro*; Nomura, Kentaro*
Journal of the Physical Society of Japan, 91(8), p.083702_1 - 083702_5, 2022/08
Times Cited Count:4 Percentile:56.47(Physics, Multidisciplinary)We investigate magnetic orderings on kagome lattice numerically from the tight-binding Hamiltonian of electrons, governed by the filling factor and spin-orbit coupling (SOC) of electrons. We find that even a simple kagome lattice model can host both ferromagnetic and noncollinear antiferromagnetic orderings depending on the electron filling, reflecting gap structures in the Dirac and flat bands characteristic to the kagome lattice. Kane-Mele- or Rashba-type SOC tends to stabilize noncollinear orderings, such a magnetic spirals and 120-degree antiferromagnetic orderings, due to the effective Dzyaloshinskii-Moriya interaction from SOC. The obtained phase structure helps qualitative understanding of magnetic orderings in various kagome-layered materials with Weyl or Dirac electrons.
Ohshima, Hiroyuki; Morishita, Masaki*; Aizawa, Kosuke; Ando, Masanori; Ashida, Takashi; Chikazawa, Yoshitaka; Doda, Norihiro; Enuma, Yasuhiro; Ezure, Toshiki; Fukano, Yoshitaka; et al.
Sodium-cooled Fast Reactors; JSME Series in Thermal and Nuclear Power Generation, Vol.3, 631 Pages, 2022/07
This book is a collection of the past experience of design, construction, and operation of two reactors, the latest knowledge and technology for SFR designs, and the future prospects of SFR development in Japan. It is intended to provide the perspective and the relevant knowledge to enable readers to become more familiar with SFR technology.
Kurebayashi, Daichi*; Araki, Yasufumi; Nomura, Kentaro*
Journal of the Physical Society of Japan, 90(8), p.084702_1 - 084702_9, 2021/08
Times Cited Count:8 Percentile:68.36(Physics, Multidisciplinary)We theoretically study current- and charge-induced spin torque in magnetic Weyl semimetals. In magnetic Weyl semimetals (WSM), topologically nontrivial band structure mediates anomalous coupling between magnetization and transport, making WSMs preferable for spintronics systems. In this paper, we determine all current-induced spin torques including spin-orbit torque and spin-transfer torque, up to first order with respect to spatial and temporal derivatives and electrical currents. We also calculate the charge-induced spin torque microscopically. We find the charge-induced spin torque originates from the chiral anomaly due to the correspondence between spin operators and axial current operators in our model.
Vermeulen, M. J.; Nishio, Katsuhisa; Hirose, Kentaro; Kean, K. R.; Makii, Hiroyuki; Orlandi, R.; Tsukada, Kazuaki; Tsekhanovich, I.*; Andreyev, A. N.; Ishizaki, Shoma*; et al.
Physical Review C, 102(5), p.054610_1 - 054610_11, 2020/11
Times Cited Count:5 Percentile:51.79(Physics, Nuclear)Sugita, Tsuyoshi; Kobayashi, Kentaro*; Yamazaki, Taiki*; Isaka, Mayu*; Itabashi, Hideyuki*; Mori, Masanobu*
Journal of Photochemistry and Photobiology A; Chemistry, 400, p.112662_1 - 112662_8, 2020/09
Times Cited Count:1 Percentile:2.44(Chemistry, Physical)In this study, we developed an in-line photocatalytic performance evaluation system in which a flow reactor was connected to the ion chromatography to accurately evaluate the performance of the photocatalyst. This system was used to evaluate the photocatalyst supported by the two-layer support method on the substrate, such as glass beads. The performance of the photocatalyst was evaluated using dimethyl sulfoxide (DMSO), and it was possible to monitor the decomposition of DMSO by UV and the formation of by-products, such as methane sulfonate (MSO) and sulfate (SA). This system can be expected to be useful not only for evaluating the decomposition performance of an object using a photocatalyst but also for evaluating the byproducts.
Mori, Masanobu*; Sugita, Tsuyoshi; Fujii, Kengo*; Yamazaki, Taiki*; Isaka, Mayu*; Kobayashi, Kentaro*; Iwamoto, Shinji*; Itabashi, Hideyuki*
Analytical Sciences, 34(12), p.1449 - 1453, 2018/12
Times Cited Count:2 Percentile:6.98(Chemistry, Analytical)The photocatalyst coating stainless-steel wire mesh (TiO-WM) was prepared by double-layer coating method. The TiO-WM was evaluated using flow analytical system, which included the reactor and conductimetric detector (FAS-CD). The DMSO decomposition test through the FAS-CD reveal that photocatalytst was stable coating on the stainless-steel wire mesh.
Sugita, Tsuyoshi; Kobayashi, Kenichi*; Kobayashi, Kentaro*; Yamazaki, Taiki*; Fujii, Kengo*; Itabashi, Hideyuki*; Mori, Masanobu*
Journal of Photochemistry and Photobiology A; Chemistry, 356, p.71 - 80, 2018/04
Times Cited Count:5 Percentile:13.08(Chemistry, Physical)Photocatalysts shows high redox property only by light irradiation. However, the reaction performance is lowered in aqueous phase due to the low contact efficiency between catalyst and targets. In this study, to enhance aqueous adsorption and photodecomposition of anionic organic target, we developed an amino functional-based spacer (3-[2-(2- aminoethylamino)ethylamino]propyl-trimethoxysilane, DETA), and used it to modify TiO. The modified catalyst with positively charged amino groups could enhance the adsorption and photodecomposition of anionic organic targets.
Sakasai, Kaoru; Sato, Setsuo*; Seya, Tomohiro*; Nakamura, Tatsuya; To, Kentaro; Yamagishi, Hideshi*; Soyama, Kazuhiko; Yamazaki, Dai; Maruyama, Ryuji; Oku, Takayuki; et al.
Quantum Beam Science (Internet), 1(2), p.10_1 - 10_35, 2017/09
Neutron devices such as neutron detectors, optical devices including supermirror devices and He neutron spin filters, and choppers are successfully developed and installed at the Materials Life Science Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC), Tokai, Japan. Four software components of MLF computational environment, instrument control, data acquisition, data analysis, and a database, have been developed and equipped at MLF. MLF also provides a wide variety of sample environment options including high and low temperatures, high magnetic fields, and high pressures. This paper describes the current status of neutron devices, computational and sample environments at MLF.
Ohae, Chiaki*; Harries, J.; Iwayama, Hiroshi*; Kawaguchi, Kentaro*; Kuma, Susumu*; Miyamoto, Yuki*; Nagasono, Mitsuru*; Nakajima, Kyo*; Nakano, Itsuo*; Shigemasa, Eiji*; et al.
Journal of the Physical Society of Japan, 85(3), p.034301_1 - 034301_10, 2016/03
Times Cited Count:8 Percentile:52.16(Physics, Multidisciplinary)Ozu, Akira; Takase, Misao*; Haruyama, Mitsuo; Kurata, Noritaka*; Kobayashi, Nozomi*; Kureta, Masatoshi; Nakamura, Tatsuya; To, Kentaro; Sakasai, Kaoru; Suzuki, Hiroyuki; et al.
Nuclear Instruments and Methods in Physics Research A, 798, p.62 - 69, 2015/10
Times Cited Count:2 Percentile:17.52(Instruments & Instrumentation)The light transport properties of scintillator light inside alternative He-3 neutron detector modules using scintillator sheets have been investigated by a ray-tracing simulation code. The detector module consists of a light-reflecting tube, a thin rectangular ceramic scintillator sheet laminated on a glass plate, and two photo-multiplier tubes (PMTs) mounted at both ends of the detector tube. The light induced on the surface of the scintillator sheet via nuclear interaction between the scintillator and neutrons are detected by the two PMTs. The light output of various detector modules in which the scintillator sheets are installed with several different arrangements were examined and evaluated in comparison with experimental results. The results derived from the simulation reveal that the light transport property is strongly dependent on the arrangement of the scintillator sheet inside the tube and the shape of the tube.
Nishio, Katsuhisa; Andreyev, A. N.*; Chapman, R.*; Derkx, X.*; Dllmann, C. E.*; Ghys, L.*; Heberger, F. P.*; Hirose, Kentaro; Ikezoe, Hiroshi*; Khuyagbaatar, J.*; et al.
Physics Letters B, 748, p.89 - 94, 2015/09
Times Cited Count:44 Percentile:92.84(Astronomy & Astrophysics)Narita, Ayumi; Kaminaga, Kiichi; Yokoya, Akinari; Noguchi, Miho; Kobayashi, Katsumi*; Usami, Noriko*; Fujii, Kentaro
Radiation Protection Dosimetry, 166(1-4), p.192 - 196, 2015/09
Times Cited Count:3 Percentile:25.64(Environmental Sciences)For the knowledge about irradiation effects of mammalian cells depending on the cell cycle, most of them had been analyzed by statistical approches. Our purpose is to establish the method for real-time observation of irradiated cells under a microscope. Fluorescent ubiquitination-based cell cycle indicator (FUCCI) human cancer (HeLa) cells (red indicates G1; green, S/G2) were exposed to a synchrotron X-ray microbeam. Cells in either G1 or S/G2 were selectively irradiated according to cell color observed in the same microscopic field in a culture dish. Time-lapse micrographs of the irradiated cells were acquired for 24 h after irradiation. The cell cycle was strongly arrested by irradiation at S/G2 and never progressed to G1. In contrast, cells irradiated at G1 progress to S/G2 with a similar time course as non-irradiated control cells. These results show single FUCCI cell exposure and live cell imaging are powerful methods for studying radiation effects on the cell cycle.
Hayashi, Kentaro*; Kasahara, Seiji; Kurihara, Kohei*; Nakagaki, Takao*; Yan, X.; Inagaki, Yoshiyuki; Ogawa, Masuro
ISIJ International, 55(2), p.348 - 358, 2015/02
Times Cited Count:8 Percentile:39.46(Metallurgy & Metallurgical Engineering)Reducing coking coal consumption and CO emissions by application of iACRES (ironmaking system based on active carbon recycling energy system) was investigated using process flow modeling to show effectiveness of HTGRs (high temperature gas-cooled reactors) adoption to iACRES. Two systems were evaluated: a SOEC (solid oxide electrolysis cell) system using CO electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H produced by IS (iodine-sulfur) process. Both the effects on saving of the coking coal and reduction of CO emissions were greater in the RWGS system. It was the reason of the result that excess H which was not consumed in the RWGS reaction was used as reducing agent in the BF as well as CO. Heat balance in the HTGR, SOEC and RWGS modules were evaluated to clarify process components to be improved. Optimization of the SOEC temperature was desired to reduce Joule heat input for high efficiency operation of the SOEC system. Higher H production thermal efficiency in the IS process for the RWGS system is effective for more efficient HTGR heat utilization. The SOEC system was able to utilize HTGR heat to reduce CO emissions more efficiently by comparing CO emissions reduction per unit heat of HTGR.
Suzuki, Katsuki*; Hayashi, Kentaro*; Kurihara, Kohei*; Nakagaki, Takao*; Kasahara, Seiji
ISIJ International, 55(2), p.340 - 347, 2015/02
Times Cited Count:19 Percentile:65.56(Metallurgy & Metallurgical Engineering)Use of the Active Carbon Recycling Energy System in ironmaking (iACRES) has been proposed for reducing CO emissions. To evaluate the performance of iACRES quantitatively, a process flow diagram of a blast furnace model with iACRES was developed using Aspen Plus, a chemical process simulator. CO emission reduction and exergy analysis were performed by using mass and energy balance obtained from simulation results. The following CO reduction methods were evaluated as iACRES: solid oxide electrolysis cells (SOEC) with CO capture and separation (CCS), SOEC without CCS, and a reverse water-gas shift reactor powered by a high-temperature gas-cooled reactor. iACRES enabled CO emission reduction by 3-11% by recycling CO and H, whereas effective exergy ratio decreased by 1-7%.
Hayashi, Kentaro*; Kasahara, Seiji; Kurihara, Kohei*; Nakagaki, Takao*; Yan, X.; Inagaki, Yoshiyuki; Ogawa, Masuro
Tanso Junkan Seitetsu Kenkyukai Saika Hokokusho; Tanso Junkan Seitetsu No Tenkai, p.42 - 62, 2015/02
Reducing coking coal consumption and CO emissions by application of HTGRs (high temperature gas-cooled reactors) to iACRES (ironmaking system based on active carbon recycling energy system) was investigated using process flow modeling. Two systems were evaluated: a SOEC (solid oxide electrolysis cell) system using CO electrolysis and a RWGS (reverse water-gas shift reaction) system using RWGS reaction with H produced by IS (iodine-sulfur) process. Coking coal consumption was reduced from a conventional BF (blast furnace) steelmaking system by 4.3% in the SOEC system and 10.3% in the RWGS system. CO emissions were decreased by 3.4% in the SOEC system and 8.2% in the RWGS system. Remaining H from the RWGS reactor was used as reducing agent in the BF in the RWGS system. This was the reason of the larger reduction of coking coal consumption and CO emissions. Electricity generation for SOEC occupied most of HTGR heat usage in the SOEC system. H production in the IS process used most of the HTGR heat in the RWGS system. Optimization of the SOEC temperature for the SOEC system and higher H production thermal efficiency in the IS process for the RWGS system will be useful for more efficient heat utilization. One typical-sized BF required 0.5 HTGRs and 2 HTGRs for in the SOEC system and RWGS system, respectively. CO emissions reduction per unit heat input was larger in the SOEC system. Recycling H to the RWGS will be useful for smaller emissions per unit heat in the RWGS system.
Hayashi, Kentaro*; Suzuki, Katsuki*; Kurihara, Kohei*; Nakagaki, Takao*; Kasahara, Seiji
Tanso Junkan Seitetsu Kenkyukai Saika Hokokusho; Tanso Junkan Seitetsu No Tenkai, p.27 - 41, 2015/02
Applying Active Carbon Recycling Energy System to ironmaking (iACRES) process is a promising technology to reduce coal usage and CO emissions. To evaluate performance of iACRES quantitatively, a process flow diagram of the blast furnace model with iACRES was developed using Aspen Plus. CO emission reduction and exergy analysis was predicted by using mass and energy balance obtained from the simulation results. The followings were investigated as iACRES: solid oxide electrolysis cells (SOEC) with CO capture and separation (CCS), SOEC without CCS, and a reverse water-gas shift reactor as the a CO reduction reactor powered by a high-temperature gas-cooled reactor. iACRES could provide CO emission reductions of 3-11% by recycling CO and H, whereas the effective exergy ratio decreased by 1-7%.
Hayashi, Kentaro*; Katayanagi, Nobuko*; Fumoto, Tamon*; Hasegawa, Toshihiro*; Ono, Keisuke*; Katata, Genki
Nogyo Kankyo Gijutsu Kenkyojo Heisei 25 Nendo Kenkyu Seika Joho, 30 (Internet), 2 Pages, 2014/03
no abstracts in English
Ozu, Akira; Takase, Misao*; Kurata, Noritaka*; Kobayashi, Nozomi*; Tobita, Hiroshi; Haruyama, Mitsuo; Kureta, Masatoshi; Nakamura, Tatsuya; Suzuki, Hiroyuki; To, Kentaro; et al.
Proceedings of 2014 IEEE Nuclear Science Symposium and Medical Imaging Conference; 21st International Symposium on Room-Temperature Semiconductor X-ray and -ray detectors (NSS/MIC 2014), 5 Pages, 2014/00
In Japan Atomic Energy Agency, the helium-3 alternative neutron detector using ceramic scintillators for nuclear safeguards is under development with the support of the government. The alternative detector module consists of four components: an aluminum regular square tube, a light reflecting foil put on the inner surface of the square tube, a rectangular scintillator sheet sintered on a glass plate, and two PMTs provided at both ends of the tube. The scintillator sheet is fit on the diagonal inside the square tube. The light transport property of scintillator lights inside the tube influences on the fundamental performance of the alternative detector. Therefore, the properties of the lights emitted on the surface of the scintillator sheet and scintillation lights passing through the glass plate to the PMTs in several arrangements of the scintillator in the tubes were investigated with a ray-tracing simulation. The results are described in comparison with the experimental results.
Katata, Genki; Hayashi, Kentaro*; Ono, Keisuke*; Nagai, Haruyasu; Miyata, Akira*; Mano, Masayoshi*
Agricultural and Forest Meteorology, 180, p.1 - 21, 2013/10
Times Cited Count:19 Percentile:65.68(Agronomy)A multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) was modified to calculate the NH exchange fluxes over a paddy field. The heat transfer at the paddy water layer and the dry deposition of water-soluble gases such as NH and SO onto the wet canopy, as well as the emission potentials of NH from the rice foliage and the surface of floodwater or soil were incorporated into the model. The modified model reproduced the observed surface and NH fluxes, paddy water temperature, and soil temperature and moisture during both the fallow and cropping seasons. The "recaptured fraction" was defined as the ratio of the amount of volatilized NH recaptured by the foliage to the total amount. Numerical experiments using the modified model with varying emission potentials of NH showed that the recaptured fraction increased with an increase in the leaf area index (LAI) and saturated when LAI 1 because of the limitation of stomatal uptake.