Thermally altered subsurface material of asteroid (162173) Ryugu

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

https://doi.org/10.1038/s41550-020-01271-2

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.

Assessment on mechanical effect of engineering barrier system to fault movement, 2

Saito, Yuya; Tanai, Kenji; Kikuchi, Hirohito*; Hirai, Takashi*; Nishimura, Mayuka*

JAEA-Research 2008-010, 35 Pages, 2008/03

JAEA-Research-2008-010.pdf:15.56MB

Site with the potential to adversely affect the performance of the disposal system should be avoided by site selection in Japan. On the other hand, according to Atomic Energy Commission, the possibility to occur the natural and artificial events suddenly should be examined. So it is important to examine about the critical state of the engineering barrier system (EBS) when if the fault move across the EBS. And this study helps to be understood by the nation. In this paper, we examined the influence of the velocity of fault movement by the model test, and tried to improve the precision of the simulation analysis. Test results showed that the total pressure of the buffer inside was about 20% decreased when the velocity was a one-tenth. And it is important to set the permeability of the near-field rock appropriately when simulating the behavior of the buffer material affected by fault movement.

Studies of superconducting alloys with structural changes induced by a mega-gravity

Nishio, Taichiro*; Hirai, Yuya*; Shimizu, Hideki*; Ono, Masao; Okayasu, Satoru; Ogata, Yudai*; Mashimo, Tsutomu*

no journal, , 

One of the ultimate goals in superconducting studies is the synthesis of a material which becomes superconducting at room temperature. However, the goal has not been in sight yet for more than 25 years after discovering a series of high-Tc copper-oxide superconductors. We think that behaviors of superconductors under extreme conditions give us a hint to obtain a higher transition temperature Tc. It is well known the Tc becomes higher under high pressure for most superconductors. The structual strain plays an important role for Tc. We forcus our attention to other structual strain caused by a mega-gravity. Under the mega-gravity, the heavier atoms move to the gravitational direction, and the lighter to the opposite. As a result, a different kind of strain can be applied. We show the changes of superconducting properties due to the maga-gravity for some superconductors.

Responses of the salt chemotaxis learning in wild type and mutant to microbeam irradiation

Suzuki, Michiyo; Hattori, Yuya; Ikeda, Hiroko; Muto, Yasuko*; Yokota, Yuichiro; Funayama, Tomoo; Hamada, Nobuyuki*; Shirai, Kana*; Kobayashi, Yasuhiko; Sakashita, Tetsuya

no journal, , 

We applied the microbeam irradiation (C, 18.3 MeV/u, LET = 119 keV/m) of the CNT in to analyze direct radiation effects at a tissue level. Also, to investigate the mechanism of modulatory effects of irradiation on the salt chemotaxis learning (SCL), we used two mutants ( and ) related to the SCL. Well-fed adults of wild-type and mutant were irradiated with 12,000 carbon ion particles corresponding to 500 Gy at 20 m micro-aperture area. Immediately after microbeam irradiation, the SCL performance was examined based on the chemotaxis index (CI). CI during the SCL was decreased in the wild-type and mutant animals, but microbeam irradiation did not significantly affect CIs of mutants. The difference of the SCL between and mutants will be discussed at the meeting.

Responses of the salt chemotaxis learning in wild type and mutant to microbeam irradiation

Sakashita, Tetsuya; Suzuki, Michiyo; Hattori, Yuya; Ikeda, Hiroko; Muto, Yasuko*; Yokota, Yuichiro; Funayama, Tomoo; Hamada, Nobuyuki*; Shirai, Kana*; Kobayashi, Yasuhiko

no journal, , 

We applied the microbeam irradiation of the central nervous tissue in to analyze direct radiation effects at a tissue level. Also, to investigate the mechanism of modulatory effects of irradiation on the salt chemotaxis learnign (SCL), we used two mutants ( and ) related to the SCL. Well-fed adults of wild-type and mutant were irradiated with 12,000 carbon ion particles corresponding to 500 Gy at micro-aperture area. Immediately after microbeam irradiation, the SCL performance was examined based on the chemotaxis index (CI). CI during the SCL was decreased in the wild-type and mutant animals, but microbeam irradiation did not significantly affect CIs of mutants. The difference of the SCL between and mutants will be discussed at the meeting.

Systematic change of strongly correlated mechanism in low carrier system semimetal CeX

Arai, Yosuke*; Kuroda, Kenta*; Tsutsui, Satoshi*; Hirai, Daigoro*; Tanaka, Hiroaki*; Yuyang, D.*; Iwata, Takuma*; Katayama, Kazu*; Shin, S.*; Kubota, Masato; et al.

no journal, , 

no abstracts in English