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Moriyama, Junichiro*; Takakuwa, Osamu*; Yamaguchi, Masatake; Ogawa, Yuhei*; Tsuzaki, Kaneaki*
Computational Materials Science, 232, p.112650_1 - 112650_11, 2024/01
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)The present study focuses on a novel hydrogen-improved strength-ductility balance in some practical Fe-Cr-Ni-based austenitic alloys, which directly depends on the solute hydrogen content. The hydrogen absorption energy of the Fe-Cr-Ni model alloys with the face-centered cubic structure was examined using first-principles calculations to verify the contribution of Cr and Ni substitutions from Fe to the hydrogen solubility in the alloys. The Cr substitution substantially reduced the hydrogen absorption energy compared to the Ni substitution, whereby the increased Cr/Ni ratio exerts higher hydrogen solubility. The propensity in the calculations coincided with the experimental results obtained previously in the practical alloys with various Cr / Ni ratios.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count：44 Percentile：96.99(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 
C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
Motokawa, Ryuhei; Endo, Hitoshi*; Yokoyama, Shingo*; Ogawa, Hiroki*; Kobayashi, Toru; Suzuki, Shinichi; Yaita, Tsuyoshi
Langmuir, 30(50), p.15127 - 15134, 2014/12
Times Cited Count：27 Percentile：63.11(Chemistry, Multidisciplinary)
-butyl phosphate/-octane mixtures by X-ray and neutron scattering in a wide 
rangeMotokawa, Ryuhei; Suzuki, Shinichi; Ogawa, Hiroki*; Antonio, M. R.*; Yaita, Tsuyoshi
Journal of Physical Chemistry B, 116(4), p.1319 - 1327, 2012/02
Times Cited Count：36 Percentile：65.28(Chemistry, Physical)
collisions at 
= 200 and 62.4 GeVAdare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.
Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06
Times Cited Count：184 Percentile：99.42(Physics, Nuclear)Transverse momentum distributions and yields for 
, and 
in collisions at = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different collisions. We also present the scaling properties such as 
and 
scaling and discuss the mechanism of the particle production in collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.
and Au+Au collisions at 
= 200 GeVAdare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.
Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04
Times Cited Count：9 Percentile：52.86(Physics, Nuclear)Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to collisions.
Kikuchi, Masahiro; Ogawa, Hideyuki*; Morishita, Norio; Ukai, Mitsuko*; Kobayashi, Yasuhiko; Shimoyama, Yuhei*
Shokuhin Shosha, 44(1-2), p.9 - 13, 2009/09
no abstracts in English
Takamura, Shuichi*; Kado, Shinichiro*; Fujii, Takashi*; Fujiyama, Hiroshi*; Takabe, Hideaki*; Adachi, Kazuo*; Morimiya, Osamu*; Fujimori, Naoji*; Watanabe, Takayuki*; Hayashi, Yasuaki*; et al.
Kara Zukai, Purazuma Enerugi No Subete, P. 164, 2007/03
no abstracts in English
Kikuchi, Masahiro; Morishita, Norio; Kobayashi, Yasuhiko; Hussain, M. S.*; Ukai, Mitsuko*; Ogawa, Hideyuki*; Shimoyama, Yuhei*
no journal, ,
no abstracts in English
Kikuchi, Masahiro; Morishita, Norio; Kobayashi, Yasuhiko; Ukai, Mitsuko*; Ogawa, Hideyuki*; Shimoyama, Yuhei*
no journal, ,
no abstracts in English
Kikuchi, Masahiro; Ogawa, Hideyuki*; Morishita, Norio; Ukai, Mitsuko*; Kobayashi, Yasuhiko; Shimoyama, Yuhei*
no journal, ,
no abstracts in English
Moriyama, Junichiro*; Takakuwa, Osamu*; Ogawa, Yuhei*; Yamaguchi, Masatake; Tsuzaki, Kaneaki*
no journal, ,
no abstracts in English
Moriyama, Junichiro*; Takakuwa, Osamu*; Yamaguchi, Masatake; Ogawa, Yuhei*; Tsuzaki, Kaneaki*
no journal, ,
In some austenitic stainless steels (Fe-Cr-Ni basic composition), hydrogen exhibits a high solution strengthening capacity with increasing solid solution hydrogen concentration that is difficult to explain by dimensional effects. In order to understand this phenomenon, it is necessary to understand the local hydrogen concentration in addition to the average solid solution hydrogen concentration in the Fe-Cr-Ni system. Since the average solid solution hydrogen concentration depends on the amount of Cr and Ni, the interaction between these substitutional atoms and hydrogen atoms is considered to be an important factor to focus on. In this study, first-principles calculations were used to quantify the interaction between Cr and Ni atoms and hydrogen atoms, and to evaluate the average solid-solution hydrogen concentration (occupancy) and its effect on the distribution.
Ito, Tatsuya; Ogawa, Yuhei*; Gong, W.; Kawasaki, Takuro; Okada, Kazuho*; Shibata, Akinobu*; Harjo, S.
no journal, ,
no abstracts in English
Ito, Tatsuya; Ogawa, Yuhei*; Gong, W.; Mao, W.; Kawasaki, Takuro; Okada, Kazuho*; Shibata, Akinobu*; Harjo, S.
no journal, ,
no abstracts in English
in situ neutron diffractionIto, Tatsuya; Ogawa, Yuhei*; Gong, W.; Mao, W.; Kawasaki, Takuro; Okada, Kazuho*; Shibata, Akinobu*; Harjo, S.
no journal, ,
no abstracts in English
