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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：97.1(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.
Shibano, Koya; Abe, Katsuo; Tsukasa, Kazuo*; Hosogane, Tatsuya; Kayano, Masashi; Sumi, Mika; Fujiwara, Hideki*; Yamaguchi, Kazuya*; Motoki, Chika*
Dai-41-Kai Nihon Kaku Busshitsu Kanri Gakkai Nenji Taikai Kaigi Rombunshu (Internet), 4 Pages, 2020/11
Large-sized dried spikes, called LSD spike, are used as reference material for accountancy analysis for Plutonium and Uranium by Isotope Dilution Mass Spectrometry. LSD spikes preparation is performed each steps as followed (1) Preparing Plutonium and Uranium mix solution, (2) Aliquoting mix solution to vials, and (3) Drying. J-MOX have planned prepared in-house LSD spike and utilized it for accountancy analysis. If LSD spikes are stored for long term, dried material peel off from bottom of vial and it may affect analytical results. In this study, LSD spikes, which have composition suitable for accountancy analysis in J-MOX, had been stored for about 2 years, then long-term stability of LSD spikes had been evaluated.
Gd
)Ni composed of heavy fermion CeNi and ferri-magnet GdNi through XMCD methodYano, Kazuo*; Okane, Tetsuo; Takeda, Yukiharu; Yamagami, Hiroshi; Fujimori, Atsushi; Nishimura, Katsuhiko*; Sato, Kiyoo*
Physica B; Condensed Matter, 515, p.118 - 125, 2017/06
Times Cited Count：1 Percentile：5.85(Physics, Condensed Matter)The electronic states of the three constituent elements in the crystal mixed system between CeNi and GdNi, CeGdNi, were investigated by soft X-ray magnetic circular dichroism (XMCD). Not only Gd 4f but also Ni 3d and Ce 4f electrons were magnetic and both magnetic moments of Ni and Ce were coupled anti-parallel to the direction of the Gd magnetic moment. After saturation, Ce magnetic moment decreased over 2 T and this behavior was explained by a spin-flip behavior of the Ce magnetic moment. In addition, sum rule analysis has revealed that the magnetic moments of Gd 4 f and Ni 3d electrons could retain small values of orbital magnetic moments.
GdNiOkane, Tetsuo; Takeda, Yukiharu; Yano, Kazuo*; Fujimori, Atsushi; Yamagami, Hiroshi; Nishimura, Katsuhiko*; Ishikawa, Yoshikazu*; Sato, Kiyoo*
JPS Conference Proceedings (Internet), 3, p.011028_1 - 011028_6, 2014/06
Gd
NiOkane, Tetsuo; Yano, Kazuo*; Yamagami, Hiroshi; Fujimori, Atsushi; Nishimura, Katsuhiko*; Ishikawa, Yoshikazu*; Sato, Kiyoo*
no journal, ,
no abstracts in English
-Lactamase TOHO-1 determined by combined high-resolution neutron and X-ray crystallographyKurihara, Kazuo; Sunami, Tomoko; Yamada, Mitsugu; Nitanai, Yasushi*; Okazaki, Nobuo; Adachi, Motoyasu; Tamada, Taro; Shimamura, Tatsuro*; Miyano, Masashi*; Ishii, Yoshikazu*; et al.
no journal, ,
To help resolve questions regarding the catalytic activity of -lactamase, the crystal structure of an unliganded form of the -lactamase Toho-1 with double mutation R274N/R276N (Toho-1/NN) has been determined by the use of high-resolution neutron and X-ray diffraction data. A large single crystal of Toho-1/NN with a dimension of 2.6 
2.5 1.3 mm
was used to collect 100 K neutron diffraction data to 1.5 
resolution and X-ray diffraction data to 1.4 resolution. The structural model of Toho-1/NN was refined to an R-factor of 19.7% using a program PHENIX. The structure showed that Glu166, a catalytic residue of Toho-1, was protonated even at pH 7 nonetheless for the close location to the positively charged side chain amino group (-NH3
) of Lys73. It is also found that there is a hydration water network bridging between the protonated Glu166 and the oxyanion hole comprising two main chain nitrogen atoms of Ser70 and Ser237. The neutron structure analysis also revealed the clear configuration of the proposed catalytic water molecule bridging Glu166 and Ser70. These observations are important to understand the catalytic action of -lactamase Toho-1.
Yano, Kimihiko; Kaji, Naoya; Washiya, Tadahiro; Saiki, Yohei*; Kakiuchi, Kazuo*; Kanaoka, Takuya*; Muta, Hiroaki*; Yamanaka, Shinsuke*
no journal, ,
no abstracts in English
