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Kobayashi, Keita; Okumura, Masahiko; Nakamura, Hiroki; Itakura, Mitsuhiro; Machida, Masahiko; Cooper, M. W. D.*
Scientific Reports (Internet), 12(1), p.9808_1 - 9808_11, 2022/06
no abstracts in English
Okita, Taira*; Terayama, Satoshi*; Tsugawa, Kiyoto*; Kobayashi, Keita; Okumura, Masahiko; Itakura, Mitsuhiro; Suzuki, Katsuyuki*
Computational Materials Science, 202, p.110865_1 - 110865_9, 2022/02
Kurita, Keisuke; Sakai, Takuro; Suzui, Nobuo*; Yin, Y.-G.*; Sugita, Ryohei*; Kobayashi, Natsuko*; Tanoi, Keitaro*; Kawachi, Naoki*
Japanese Journal of Applied Physics, 60(11), p.116501_1 - 116501_4, 2021/11
Radioisotope tracer imaging is useful for studying plant physiological phenomena. In this study, we developed an autoradiography system with phosphor powder (ZnS:Ag), "Live-autoradiography", for imaging radioisotope dynamics in a living plant. This system visualizes the element migration and accumulation in intact plants continuously under a light environment. An imaging test was performed on point sources of 
Cs, with a radioactivity of 10-100 kBq of being observed; this indicates satisfactory system linearity between the image intensity and the radioactivity of Cs. Moreover, dynamics imaging of Cs was performed on an intact soybean plant for four days. The serial images indicated Cs accumulation in the node, vein, and growing point of the plant. The developed system can be used for studying plant physiological phenomena and can be employed for quantitative measurement of radionuclides.
molecular dynamics simulations using the SCAN meta-GGA density functional and EXAFS spectroscopy studiesYamaguchi, Akiko; Kobayashi, Keita; Takahashi, Yoshio*; Machida, Masahiko; Okumura, Masahiko
Chemical Physics Letters, 780, p.138945_1 - 138945_5, 2021/10
Times Cited Count：0 Percentile：0.01(Chemistry, Physical)no abstracts in English
Kobayashi, Keita; Nagai, Yuki; Itakura, Mitsuhiro; Shiga, Motoyuki
Journal of Chemical Physics, 155(3), p.034106_1 - 034106_9, 2021/07
Times Cited Count：0 Percentile：0.01(Chemistry, Physical)no abstracts in English
Kobayashi, Keita; Nakamura, Hiroki; Yamaguchi, Akiko; Itakura, Mitsuhiro; Machida, Masahiko; Okumura, Masahiko
Computational Materials Science, 188, p.110173_1 - 110173_14, 2021/02
Times Cited Count：0 Percentile：0(Materials Science, Multidisciplinary)no abstracts in English
Nagai, Yuki; Okumura, Masahiko; Kobayashi, Keita*; Shiga, Motoyuki
Physical Review B, 102(4), p.041124_1 - 041124_6, 2020/07
Times Cited Count：2 Percentile：44.66(Materials Science, Multidisciplinary)no abstracts in English
Kobayashi, Keita*; Okumura, Masahiko; Yamada, Susumu; Machida, Masahiko; Aoki, Hideo*
Physical Review B, 94(21), p.214501_1 - 214501_7, 2016/12
Times Cited Count：38 Percentile：88.59(Materials Science, Multidisciplinary)no abstracts in English
Saigusa, Mikio*; Oyama, Gaku*; Matsubara, Fumiaki*; Takii, Keita*; Sai, Takuma*; Kobayashi, Takayuki; Moriyama, Shinichi
Fusion Engineering and Design, 96-97, p.577 - 582, 2015/10
Times Cited Count：4 Percentile：32.14(Nuclear Science & Technology)A wideband polarizer has been developed for an ECCD system in JT-60SA. The groove depth of the mirrors installed in miter bends were optimized for two frequencies (110 GHz and 138 GHz) by numerical simulations. All surfaces of Poincare spheres were covered at both of the frequencies in low power test. The thermal stress of polarizer were estimated by the numerical simulations. The twister polarizer has been tested up to 0.24 MW during 3 s at 110 GHz.
Kobayashi, Keita; Okumura, Masahiko; Ota, Yukihiro*; Yamada, Susumu; Machida, Masahiko
JPS Conference Proceedings (Internet), 3, p.016006_1 - 016006_6, 2014/06
no abstracts in English
-orbital attractive one-dimensional fermionic optical latticesKobayashi, Keita; Ota, Yukihiro; Okumura, Masahiko; Yamada, Susumu; Machida, Masahiko
Physical Review A, 89(2), p.023625_1 - 023625_6, 2014/02
Times Cited Count：8 Percentile：47.84(Optics)no abstracts in English
Kobayashi, Keita; Machida, Masahiko; Ota, Yukihiro*; Nori, F.*
Physical Review B, 88(22), p.224516_1 - 224516_5, 2013/12
Times Cited Count：16 Percentile：62.34(Materials Science, Multidisciplinary)no abstracts in English
Kobayashi, Keita; Ota, Yukihiro*; Machida, Masahiko
Physica C, 494, p.13 - 16, 2013/11
Times Cited Count：4 Percentile：23.31(Physics, Applied)no abstracts in English
Machida, Masahiko; Kobayashi, Keita; Koyama, Tomio*
Physica C, 491, p.44 - 46, 2013/08
Times Cited Count：1 Percentile：5.74(Physics, Applied)no abstracts in English
Kobayashi, Keita; Okumura, Masahiko; Ota, Yukihiro*; Yamada, Susumu; Machida, Masahiko
Physical Review Letters, 109(23), p.235302_1 - 235302_5, 2012/12
Times Cited Count：22 Percentile：75.43(Physics, Multidisciplinary)no abstracts in English
Kawamura, Yoshinori; Ochiai, Kentaro; Hoshino, Tsuyoshi; Kondo, Keitaro*; Iwai, Yasunori; Kobayashi, Kazuhiro; Nakamichi, Masaru; Konno, Chikara; Yamanishi, Toshihiko; Hayashi, Takumi; et al.
Fusion Engineering and Design, 87(7-8), p.1253 - 1257, 2012/08
Times Cited Count：15 Percentile：78.3(Nuclear Science & Technology)Tritium generation and recovery study on lithium ceramic packed bed was started by use of FNS in JAEA. Lithium titanate was selected as tritium breeding material. In this work, the effect of sweep gas species on tritium release behavior was investigated. In case of sweep by helium with 1% of hydrogen, tritium in water form was released sensitively corresponding to the irradiation. This is due to existence of the water vapor in the sweep gas. On the other hand, in case of sweep by dry helium, tritium in gaseous form was released first, and release of tritium in water form was delayed and was gradually increased.
Ota, Yukihiro*; Kobayashi, Keita; Machida, Masahiko; Koyama, Tomio*; Nori, F.*
Physics Procedia, 27, p.352 - 355, 2012/00
Times Cited Count：2 Percentile：66.99no abstracts in English
Miyazawa, Yutaka*; Sakashita, Tetsuya; Funayama, Tomoo; Hamada, Nobuyuki*; Negishi, Hiroshi*; Kobayashi, Akie*; Kaneyasu, Tomoko*; Oba, Atsushi*; Morohashi, Keita*; Kakizaki, Takehiko*; et al.
Journal of Radiation Research, 49(4), p.373 - 379, 2008/07
Times Cited Count：24 Percentile：62.01(Biology)We examined the role of root cap and elongation zone cells in root hydrotropism using heavy-ion and laser microbeam. Heavy-ion microbeam irradiation of the elongation zone, but not that of the columella cells, significantly and temporary suppressed the development of hydrotropic curvature. However, laser ablation confirmed that columella cells are indispensable for hydrotropism. Systemic heavy-ion broad-beam irradiation suppressed 
expression of 
gene, but not 
gene. Our results indicate that both the root cap and elongation zone have indispensable and functionally distinct roles in root hydrotropism, and that gene expression might be required for hydrotropism in the elongation zone, but not in columella cells.
Kobayashi, Keita*; Mine, Makoto*; Okumura, Masahiko; Yamanaka, Yoshiya*
Soryushiron Kenkyu, 116(2), p.B64 - B66, 2008/06
no abstracts in English
using heavy-ion microbeamMiyazawa, Yutaka*; Sakashita, Tetsuya; Negishi, Hiroshi*; Kobayashi, Akie*; Kaneyasu, Tomoko*; Oba, Atsushi*; Morohashi, Keita*; Kakizaki, Takehiko*; Funayama, Tomoo; Hamada, Nobuyuki*; et al.
JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 116, 2008/03
We examined the role of root cap and elongation zone cells in root hydrotropism of using heavy ion and laser microbeam. Heavy ion microbeam irradiation of the elongation zone, but not that of the columella cells, significantly and temporarily suppressed the development of hydrotropic curvature. However, laser ablation confirmed that columella cells are indispensable for hydrotropism. Systemic heavy ion broad beam irradiation suppressed de novo expression of INDOLE ACETIC ACID 5 gene. Our results indicate that both the root cap and elongation zone have indispensable and functionally distinct roles in root hydrotropism, and that de novo gene expression might be required for hydrotropism in the elongation zone, but not in columella cells.
