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Shimizu, Kazuyuki*; Nishimura, Katsuhiko*; Matsuda, Kenji*; Akamaru, Satoshi*; Nunomura, Norio*; Namiki, Takahiro*; Tsuchiya, Taiki*; Lee, S.*; Higemoto, Wataru; Tsuru, Tomohito; et al.
Scripta Materialia, 245, p.116051_1 - 116051_6, 2024/05
Hydrogen at the mass ppm level causes hydrogen embrittlement in metallic materials, but it is extremely difficult to experimentally elucidate the hydrogen trapping sites. We have taken advantage of the fact that positive muons can act as light isotopes of hydrogen to study the trapping state of hydrogen in matter. Zero-field muon spin relaxation experiments and the density functional theory (DFT) calculations for hydrogen trapping energy are carried out for AlMn. The DFT calculations for hydrogen in AlMn have found four possible trapping sites in which the hydrogen trapping energies are 0.168 (site 1), 0.312 (site 2), 0.364 (site 3), and 0.495 (site 4) in the unit of eV/atom. Temperature variations of the deduced dipole field width () indicated step-like changes at temperatures, 94, 193, and 236 K. Considering their site densities, the observed change temperatures are interpreted by trapping muons at sites 1, 3, and 4.
Nishimura, Hiroki*; Kozuka, Mariko*; Fukuda, Akari*; Ishimura, Toyoho*; Amano, Yuki; Beppu, Hikari*; Miyakawa, Kazuya; Suzuki, Yohei*
Environmental Microbiology Reports (Internet), 15(3), p.197 - 205, 2023/06
Times Cited Count:1 Percentile:59.23(Environmental Sciences)The family Methanoperedenaceae archaea mediate anaerobic oxidation of methane (AOM). We newly developed a high-pressure laboratory incubation system and investigated groundwater from 214- and 249-m deep boreholes at Horonobe Underground Research Laboratory, Japan, where the high and low abundances of Methanoperedenaceae archaea have been revealed, respectively. We incubated the samples amended with or without amorphous Fe(III) and C-labelled methane at an in-situ pressure of 1.6 MPa. After three to seven-day incubation, AOM activities were not detected from the 249-m sample but from the 214-m sample. The AOM rates were 93.740.6 and 27.737.5 nM/day with and without Fe(III) amendment. Suspended particulates were not visible in the 249-m sample on the filter, while they were abundant and contained amorphous Fe(III) and Fe(III)-bearing phyllosilicates in the 214-m sample. This supports the in-situ activity of Fe(III)-dependent AOM in the deep subsurface borehole.
Bendo, A.*; Matsuda, Kenji*; Nishimura, Katsuhiko*; Nunomura, Norio*; Tsuchiya, Taiki*; Lee, S.*; Marioara, C. D.*; Tsuru, Tomohito; Yamaguchi, Masatake; Shimizu, Kazuyuki*; et al.
Materials Science and Technology, 36(15), p.1621 - 1627, 2020/09
Times Cited Count:8 Percentile:47.13(Materials Science, Multidisciplinary)Metastable phases in aluminum alloys are the primary nano-scale precipitates which have the biggest contribution to the increase in the tangible mechanical properties. The continuous increase in hardness in the 7xxx aluminum alloys is associated with the phase transformation from clusters or GP-zones to the metastable phase. The transformation which is structural and compositional should occur following the path of the lowest activation energy. This work is an attempt to gain insight into how the structural transformation may occur based on the shortest route of diffusion for the eventual structure to result in that of phase. However, for the compositional transformation to occur, the proposed mechanism may not stand, since it is a prerequisite for the atoms to be at very precise positions in the aluminum lattice, at the very beginning of structural transformation, which may completely differ from that of the GP-zones atomic arrangements.
Matsuda, Kenji*; Yasumoto, Toru*; Bendo, A.*; Tsuchiya, Taiki*; Lee, S.*; Nishimura, Katsuhiko*; Nunomura, Norio*; Marioara, C. D.*; Lervik, A.*; Holmestad, R.*; et al.
Materials Transactions, 60(8), p.1688 - 1696, 2019/08
Times Cited Count:14 Percentile:63.04(Materials Science, Multidisciplinary)no abstracts in English
Nishimura, Katsuhiko*; Matsuda, Kenji*; Lee, S.*; Nunomura, Norio*; Shimano, Tomoki*; Bendo, A.*; Watanabe, Katsumi*; Tsuchiya, Taiki*; Namiki, Takahiro*; Toda, Hiroyuki*; et al.
Journal of Alloys and Compounds, 774, p.405 - 409, 2019/02
Times Cited Count:3 Percentile:17.96(Chemistry, Physical)Toda, Hiroyuki*; Yamaguchi, Masatake; Matsuda, Kenji*; Shimizu, Kazuyuki*; Hirayama, Kyosuke*; Su, H.*; Fujihara, Hiro*; Ebihara, Kenichi; Itakura, Mitsuhiro; Tsuru, Tomohito; et al.
Tetsu To Hagane, 105(2), p.240 - 253, 2019/02
Times Cited Count:0 Percentile:0(Metallurgy & Metallurgical Engineering)no abstracts in English
Steppenbeck, D.*; Takeuchi, Satoshi*; Aoi, Nori*; Doornenbal, P.*; Matsushita, Masafumi*; Wang, H.*; Baba, Hidetada*; Go, Shintaro*; Holt, J. D.*; Lee, J.*; et al.
Physical Review C, 96(6), p.064310_1 - 064310_10, 2017/12
Times Cited Count:18 Percentile:80.82(Physics, Nuclear)no abstracts in English
Steppenbeck, D.*; Takeuchi, Satoshi*; Aoi, Nori*; Doornenbal, P.*; Matsushita, Masafumi*; Wang, H.*; Utsuno, Yutaka; Baba, Hidetada*; Go, Shintaro*; Lee, J.*; et al.
Physical Review Letters, 114(25), p.252501_1 - 252501_6, 2015/06
Times Cited Count:44 Percentile:87.83(Physics, Multidisciplinary)The neutron-rich nucleus Ar is produced by the fragmentation reactions of Ca, Sc, and Ti at the RIBF facility in RIKEN, and its deexcited rays are observed for the first time. The first level in Ar is identified to lie at 1178(18)keV from the most intense -ray spectra. This experimental data, together with the systematics of the levels for surrounding nuclei, is analyzed with large-scale shell-model calculations. Consequently, the sub-shell gap in Ar is equivalent to that of Ca, thus making the level in Ar higher than that of Ar. The shell-model calculation also predicts that the sub-shell gap enhances in going from Ca to Ar, which will be verified by forthcoming experiments for Ar.
Watanabe, H.*; Lorusso, G.*; Nishimura, Shunji*; Otsuka, T.*; Ogawa, K.*; Xu, Z. Y.*; Sumikama, Toshiyuki*; Sderstrm, P.-A.*; Doornenbal, P.*; Li, Z.*; et al.
Physical Review Letters, 113(4), p.042502_1 - 042502_6, 2014/07
Times Cited Count:24 Percentile:76.91(Physics, Multidisciplinary)Steppenbeck, D.*; Takeuchi, Satoshi*; Aoi, Nori*; Doornenbal, P.*; Matsushita, Masafumi*; Wang, H.*; Baba, Hidetada*; Fukuda, Naoki*; Go, Shintaro*; Homma, Michio*; et al.
Nature, 502(7470), p.207 - 210, 2013/10
Times Cited Count:285 Percentile:99.78(Multidisciplinary Sciences)no abstracts in English
Nishimura, Hiroki*; Kozuka, Mariko*; Fukuda, Akari*; Ishimura, Toyoho*; Amano, Yuki; Beppu, Hikari*; Miyakawa, Kazuya; Suzuki, Yohei*
no journal, ,
The family Methanoperedenaceae archaea mediate anaerobic oxidation of methane (AOM). We newly developed a high-pressure laboratory incubation system and investigated groundwater from 214- and 249-m deep boreholes at Horonobe Underground Research Laboratory, Japan, where the high and low abundances of Methanoperedenaceae archaea have been revealed, respectively. We incubated the samples amended with or without amorphous Fe(III) and C-labelled methane at an in-situ pressure of 1.6 MPa. After three to seven-day incubation, AOM activities were not detected from the 249-m sample but from the 214-m sample. The AOM rates were 93.740.6 and 27.737.5 nM/day with and without Fe(III) amendment. Suspended particulates were not visible in the 249-m sample on the filter, while they were abundant and contained amorphous Fe(III) and Fe(III)-bearing phyllosilicates in the 214-m sample. This supports the in-situ activity of Fe(III)-dependent AOM in the deep subsurface borehole.
Nishimura, Hiroki*; Kozuka, Mariko*; Fukuda, Akari*; Ishimura, Toyoho*; Amano, Yuki; Beppu, Hikari*; Miyakawa, Kazuya; Suzuki, Yohei*
no journal, ,
no abstracts in English