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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：43 Percentile：96.93(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.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.
Science, 364(6437), p.272 - 275, 2019/04
Times Cited Count：259 Percentile：99.73(Multidisciplinary Sciences)The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.
Ueda, Daisuke*; Shirai, Koji*; Funayama, Tomoo; Sakashita, Tetsuya; Yokota, Yuichiro; Kobayashi, Yasuhiko
JAEA-Review 2014-050, JAEA Takasaki Annual Report 2013, P. 84, 2015/03
In this study, we investigated the effects of irradiation to the silkworm eggs at various developmental stages. First, we tried the irradiation to the unfertilized eggs (at 1.5 hour after oviposition). At this stage, the female pronucleus and the sperm nucleus are observed in the eggs, but not fertilized. After irradiation, the irradiated eggs stopped the development after fertilization. About 2 hours after, the egg restarted the nuclear cleavage. This result indicates the DNA damage on pronuleus cannot prevent the fertilization. We also investigated the effects of irradiation to the egg at the nuclear cleavage stage (at 6 hour after oviposition). The egg also stopped the development after irradiation, but the duration time of the developmental arrest was almost two times longer (about 4 hours) than that of the egg irradiated at fertilization.
Se
Ye, M.*; Kuroda, Kenta*; Takeda, Yukiharu; Saito, Yuji; Okamoto, Kazuaki*; Zhu, S.-Y.*; Shirai, Kaito*; Miyamoto, Koji*; Arita, Masashi*; Nakatake, Masashi*; et al.
Journal of Physics; Condensed Matter, 25(23), p.232201_1 - 232201_5, 2013/06
Times Cited Count：12 Percentile：48.79(Physics, Condensed Matter)no abstracts in English
Noda, Akira*; Nakao, Masao*; Soda, Hikaru*; Tongu, Hiromu*; Jimbo, Koichi*; Okamoto, Hiromi*; Osaki, Kazuya*; Yuri, Yosuke; Meshkov, I.*; Smirnov, A.*; et al.
Proceedings of 23rd Russian Particle Accelerator Conference (RuPAC 2012) (Internet), p.48 - 52, 2012/09
Ito, Kenji*; Oka, Toshitaka*; Kobayashi, Yoshinori*; Shirai, Yasuharu*; Wada, Kenichiro*; Matsumoto, Masataka*; Fujinami, Masanori*; Hirade, Tetsuya; Honda, Yoshihide*; Hosomi, Hiroyuki*; et al.
Materials Science Forum, 607, p.248 - 250, 2009/00
So far no standard procedure for the positron annihilation lifetime (PAL) technique has been established. A lack of the standards has led to difficulty in ensuring the equivalency and reliability of data from different laboratories. As a first, we conducted an interlaboratory comparison of PAL measurements for metal, polymer and silica glass with agreed procedures for data recording and analysis. The PAL data recorded at different laboratories were analyzed with a single lifetime component for the metal sample and with three components for the others, respectively. Based on the results of the reported positron and ortho-positronium lifetimes, the possible sources of the uncertainties in the PAL measurements are discussed. To reduce the effect of scattered 
rays, a lead shield was placed between the detectors. The uncertainty was significantly decreased, signifying that placing lead shields between the detectors effectively reduced the false signals due to the scattered rays.
Ito, Kenji*; Oka, Toshitaka*; Kobayashi, Yoshinori*; Shirai, Yasuharu*; Wada, Kenichiro*; Matsumoto, Masataka*; Fujinami, Masanori*; Hirade, Tetsuya; Honda, Yoshihide*; Hosomi, Hiroyuki*; et al.
Journal of Applied Physics, 104(2), p.026102_1 - 026102_3, 2008/07
Times Cited Count：48 Percentile：83.5(Physics, Applied)Interlaboratory comparison of positron annihilation lifetime measurements using synthetic fused silica and polycarbonate was conducted with the participation of 12 laboratories. By regulating procedures for the measurement and data analysis the uncertainties of the positron lifetimes obtained at different laboratories were significantly reduced in comparison with those reported in the past.
Shirai, Toshiyuki*; Tanabe, Mikio*; Soda, Hikaru*; Ikegami, Masahiro*; Fujimoto, Shinji*; Tongu, Hiromu*; Noda, Akira*; Noda, Koji*; Shibuya, Shinji*; Fujimoto, Tetsuya*; et al.
Proceedings of 9th Symposium on Accelerator and Related Technology for Application, p.19 - 22, 2007/06
Fukamoto, Kana; Shirai, Koji*; Sakata, Toshiyuki*; Sakashita, Tetsuya; Funayama, Tomoo; Hamada, Nobuyuki*; Wada, Seiichi*; Kakizaki, Takehiko; Shimura, Sachiko*; Kobayashi, Yasuhiko; et al.
Journal of Radiation Research, 48(3), p.247 - 253, 2007/05
Times Cited Count：17 Percentile：47.8(Biology)To carry out the radio-microsurgery study using silkworm, 
, we have already developed the specific irradiation systems for eggs and third to fifth instar larvae. In this study, a modified application consisting of the first instar silkworm larvae was further developed using heavy-ion microbeams. This system includes aluminum plates with holes specially designed to fix the first instar silkworm larvae during irradiation, and Mylar films were used to adjust energy deposited for planning radiation doses at certain depth. Using this system, the suppression of abnormal proliferation of epidermal cells in the knob mutant was examined. Following target irradiation of the knob-forming region at the first instar stage with 180-mum-diameter microbeam of 220 MeV carbon (
C) ions, larvae were reared to evaluate the effects of irradiation. The results indicated that the knob formation at the irradiated segment was specially suppressed in 5.9, 56.4, 66.7 and 73.6 % of larvae irradiated with 120, 250, 400 and 600 Gy, respectively, but the other knob formations at the non-irradiated segments were not suppressed in either irradiation. Although some larva did not survive undesired non-targeted exposure, our present results indicate that this method would be useful to investigate the irradiation effect on a long developmental period of time. Moreover, our system could also be applied to other species by targeting tissues, or organs during development and metamorphosis in insect and animals.
, after heavy-ion irradiation; Analysis by transplantation of the irradiated organs using a transgenic silkworm strainKiguchi, Kenji*; Shirai, Koji*; Sakata, Toshiyuki*; Fukamoto, Kana; Kakizaki, Takehiko; Wada, Seiichi*; Sakashita, Tetsuya; Funayama, Tomoo; Hamada, Nobuyuki*; Kobayashi, Yasuhiko
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 117, 2007/02
no abstracts in English
cyst formation from the implanted larval integument in the sweet potato hornworm, 
; A Simple model for studying wound healingFukamoto, Kana; Shirai, Koji*; Sato, Shigeru*; Kanekatsu, Rensuke*; Kiguchi, Kenji*; Kobayashi, Yasuhiko
Journal of Insect Biotechnology and Sericology, 75(3), p.99 - 106, 2006/10
no abstracts in English
Fukamoto, Kana; Shimura, Sachiko*; Shirai, Koji*; Kanekatsu, Rensuke*; Kiguchi, Kenji*; Sakashita, Tetsuya; Funayama, Tomoo; Kobayashi, Yasuhiko
Journal of Insect Biotechnology and Sericology, 75(3), p.107 - 114, 2006/10
no abstracts in English
Yoshida, Yumi*; Maeda, Koji*; Shirai, Osamu*; Onuki, Toshihiko
Chemistry Letters, 35(1), p.132 - 133, 2006/01
Times Cited Count：2 Percentile：13.65(Chemistry, Multidisciplinary)no abstracts in English
C
) irradiated hematopoietic organs in the silkworm, , through the way of phagocytosis of injured cells after invasionLing, E.*; Shirai, Koji*; Kanekatsu, Rensuke*; Kiguchi, Kenji*; Kobayashi, Yasuhiko; Funayama, Tomoo; Watanabe, Hiroshi*
Developmental and Comparative Immunology, 30(6), p.531 - 543, 2006/00
Times Cited Count：13 Percentile：54.39(Fisheries)no abstracts in English
Matsukado, Koji*; Esirkepov, T. Z.; Kinoshita, Kenichi*; Daido, Hiroyuki; Utsumi, Takayuki*; Li, Z.*; Fukumi, Atsushi*; Hayashi, Yukio; Orimo, Satoshi; Nishiuchi, Mamiko; et al.
Physical Review Letters, 91(21), p.215001_1 - 215001_4, 2003/11
Times Cited Count：136 Percentile：95.25(Physics, Multidisciplinary)no abstracts in English
, after locally targeted irradiation with heavy ion beamsLing, E.*; Fukamoto, Kana*; Xu, S.*; Shirai, Koji*; Kanekatsu, Rensuke*; Kobayashi, Yasuhiko; Tu, Z.; Funayama, Tomoo; Watanabe, Hiroshi; Kiguchi, Kenji*
Journal of Insect Biotechnology and Sericology, 72(2), p.95 - 100, 2003/09
no abstracts in English
?Ling, E.*; Shirai, Koji*; Kanekatsu, Rensuke*; Kobayashi, Yasuhiko; Tu, Z.; Funayama, Tomoo; Watanabe, Hiroshi; Kiguchi, Kenji*
Journal of Insect Biotechnology and Sericology, 72(2), p.101 - 109, 2003/09
no abstracts in English
Kusakabe, Toshio*; Miyamoto, Yoshiharu*; Ishida, Rikiya*; Ito, Kojiro*; Kuroyanagi, Nobuhiro*; Nakai, Yota*; Shirai, Toshizo
Nuclear Instruments and Methods in Physics Research B, 205, p.600 - 604, 2003/05
Times Cited Count：6 Percentile：43.07(Instruments & Instrumentation)no abstracts in English
Miura, Yukitoshi; Fujita, Takaaki; Oikawa, Toshihiro; Suzuki, Takahiro; Ide, Shunsuke; Sakamoto, Yoshiteru; Koide, Yoshihiko; Hatae, Takaki; Naito, Osamu; Isayama, Akihiko; et al.
IAEA-CN-94/EX/C3-1Ra (CD-ROM), 5 Pages, 2002/00
no abstracts in English
Sakamoto, Yoshiteru; Kamada, Yutaka; Ide, Shunsuke; Fujita, Takaaki; Shirai, Hiroshi; Takizuka, Tomonori; Koide, Yoshihiko; Fukuda, Takeshi; Oikawa, Toshihiro; Suzuki, Takahiro; et al.
Nuclear Fusion, 41(7), p.865 - 872, 2001/07
Times Cited Count：106 Percentile：93.35(Physics, Fluids & Plasmas)no abstracts in English
