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Miura, Hikaru*; Ishimaru, Takashi*; Ito, Yukari*; Kuribara, Yuichi; Otosaka, Shigeyoshi*; Sakaguchi, Aya*; Misumi, Kazuhiro*; Tsumune, Daisuke*; Kubo, Atsushi*; Higaki, Shogo*; et al.
Scientific Reports (Internet), 11, p.5664_1 - 5664_11, 2021/03
Times Cited Count：8 Percentile：64.15(Multidisciplinary Sciences)For the first time, we isolated and investigated seven CsMPs (radioactive caesium-bearing microparticles) from marine particulate matter and sediment. From the elemental composition, the 
Cs/
Cs activity ratio, and the Cs activity per unit volume results, we inferred that the five CsMPs collected from particulate matter were emitted from Unit 2 of the FDNPP, whereas the two CsMPs collected from marine sediment were possibly emitted from Unit 3. The presence of CsMPs can cause overestimation of the solid-water distribution coefficient of Cs in marine sediments and particulate matter and a high apparent radiocaesium concentration factor for marine biota. CsMPs emitted from Unit 2, which were collected from the estuary of a river that flowed through a highly contaminated area, may have been deposited on land and then transported by the river. By contrast, CsMPs emitted from Unit 3 were possibly transported eastward by the wind and deposited directly onto the ocean surface.
Miura, Hikaru*; Kuribara, Yuichi; Yamamoto, Masayoshi*; Sakaguchi, Aya*; Yamaguchi, Noriko*; Sekizawa, Oki*; Nitta, Kiyofumi*; Higaki, Shogo*; Tsumune, Daisuke*; Itai, Takaaki*; et al.
Scientific Reports (Internet), 10, p.11421_1 - 11421_9, 2020/07
Times Cited Count：14 Percentile：69.92(Multidisciplinary Sciences)Kurihara, Momo*; Yasutaka, Tetsuo*; Aono, Tatsuo*; Ashikawa, Nobuo*; Ebina, Hiroyuki*; Iijima, Takeshi*; Ishimaru, Kei*; Kanai, Ramon*; Karube, Jinichi*; Konnai, Yae*; et al.
Journal of Radioanalytical and Nuclear Chemistry, 322(2), p.477 - 485, 2019/11
Times Cited Count：2 Percentile：25.74(Chemistry, Analytical)We assessed the repeatability and reproducibility of methods for determining low dissolved radiocesium concentrations in freshwater in Fukushima. Twenty-one laboratories pre-concentrated three of 10 L samples by five different pre-concentration methods (prussian-blue-impregnated filter cartridges, coprecipitation with ammonium phosphomolybdate, evaporation, solid-phase extraction disks, and ion-exchange resin columns), and activity of radiocesium was measured. The z-scores for all of the Cs results were within 
2, indicating that the methods were accurate. The relative standard deviations (RSDs) indicating the variability in the results from different laboratories were larger than the RSDs indicating the variability in the results from each separate laboratory.
) of radiocesium in the Kuchibuto River in FukushimaMiura, Hikaru*; Kurihara, Yuichi*; Sakaguchi, Aya*; Tanaka, Kazuya; Yamaguchi, Noriko*; Higaki, Shogo*; Takahashi, Yoshio*
Geochemical Journal, 52(2), p.145 - 154, 2018/00
Times Cited Count：43 Percentile：94.32(Geochemistry & Geophysics)Solid-water distribution coefficient () of radiocesium in rivers is apparently increased due to the possible presence of highly radioactive radiocesium-bearing microparticles (CsMPs) in the solid phase. In this study, we evaluated the contribution of CsMPs to apparent Kd values. The ratio of the radioactivity of the separated CsMPs to the total radiocesium on fluvial suspended particles ranged from 0 to 46%. This means that the existence of CsMPs in fluvial suspended partcles did not change apparent Kd values in order magnitude.
Yoshimura, Kazuya; Onda, Yuichi*; Sakaguchi, Aya*; Yamamoto, Masayoshi*; Matsuura, Yuki*
Journal of Environmental Radioactivity, 139, p.370 - 378, 2015/01
Times Cited Count：82 Percentile：93.1(Environmental Sciences)
AsKobayashi, Hisao*; Ikeda, Shugo*; Sakaguchi, Yui*; Yoda, Yoshitaka*; Nakamura, Hiroki; Machida, Masahiko
Journal of Physics; Condensed Matter, 25(2), p.022201_1 - 022201_6, 2013/01
Times Cited Count：9 Percentile：41.68(Physics, Condensed Matter)The electronic and vibrational properties of EuFeAs in the tetragonal phase between 0 and 5 GPa have been investigated using 
Fe M
ssbauer spectroscopy and Fe nuclear resonance inelastic scattering, respectively. We find a discontinuous increase of the center shift around 2.3 GPa, reflecting a change of the electronic state of Fe, and above 2.5 GPa a softening of the optical phonon modes associated with an increase of the relative volume of the FeAs
tetrahedron in the unit cell. Our findings reveal that an effective As-As hybridization along the c axis appears at approximately 2.3 GPa in the tetragonal phase of EuFeAs, along with a change in the electronic state of Fe, causing bulk superconductivity to appear at a low temperature. Consequently, the change in the electronic state of the Fe atom and the effective As-As hybridization play key roles in the pressure-induced superconductivity in the tetragonal phase of AFeAs.
Akiyama, Kazuhiko; Zhao, Y.*; Sueki, Keisuke*; Tsukada, Kazuaki; Haba, Hiromitsu; Nagame, Yuichiro; Kodama, Takeshi*; Suzuki, Shinzo*; Otsuki, Tsutomu*; Sakaguchi, Masahiko*; et al.
Journal of the American Chemical Society, 123(1), p.181 - 182, 2001/01
Times Cited Count：64 Percentile：84.55(Chemistry, Multidisciplinary)no abstracts in English
Sakaguchi, Hiroki*; Hatakeyama, Keisuke*; Satake, Yuichi*; Fujine, Shigenori*; Yoneda, Kenji*; Kanda, Keiji*; Matsubayashi, Masahito; Esaka, Takao*
Kashika Joho Gakkai-Shi, 20(suppl.1), p.373 - 374, 2000/07
no abstracts in English
Taniguchi, Keisuke*; Yoshimura, Kazuya; Smith, H.*; Blake, W.*; Yamamoto, Masayoshi*; Yokoyama, Akihiko*; Takahashi, Yoshio*; Sakaguchi, Aya*; Onda, Yuichi*
no journal, ,
no abstracts in English
Taniguchi, Keisuke*; Yoshimura, Kazuya; Smith, H.*; Blake, W.*; Takahashi, Yoshio*; Sakaguchi, Aya*; Yamamoto, Masayoshi*; Onda, Yuichi*
no journal, ,
no abstracts in English
Miura, Hikaru*; Kuribara, Yuichi; Yamamoto, Masayoshi*; Sakaguchi, Aya*; Higaki, Shogo*; Takahashi, Yoshio*
no journal, ,
A synchrotron radiation X-ray analysis was performed on radioactive particles released into the environment due to the Fukushima Dai-ichi Nuclear Power Plant accident, uranium particles (4 valence and 6 valence) with a size of several microns were present in the particles from the Unit 1. Since these uranium particles also contain zirconium, which is considered to be derived from the fuel cladding, it was presumed that the eutectic mixture of the fuel in the reactor and its cladding was incorporated into the radioactive particulates and released into the environment.
Sugiyama, Koichi*; Go, Shintaro*; Tomimatsu, Taro*; Kai, Tamito*; Nagae, Daisuke*; Ishibashi, Yuichi*; Matsunaga, Sotaro*; Nagata, Yuto*; Nishibata, Hiroki*; Washiyama, Kohei*; et al.
no journal, ,
We have successfully performed in-beam gamma-ray spectroscopy using the isomer-scope technique to study excited-state structure of neutron-rich heavy-actinide nuclei. The neutron-rich heavy-actinide nuclei were produced in the multinucleon-transfer reactions with a 
Cm target and 
O projectiles accelerated with the JAEA tandem accelerator. Projectile-like scattered particles were detected with Si E-
E telescopes placed at the backward angle, and target-like scattered particles of isomers were caught by an annular aluminum plate placed at about 60-mm downstream from the target. Four Ge detectors and 4 LaBr detectors were placed at the periphery of the aluminum plate, and detected gamma rays from the isomers. Gamma rays emitted from the actinide isomers were successfully observed with a good sensitivity owing to the tungsten shield placed between the target and the detectors.
Asai, Masato; Ishibashi, Yuichi*; Niwase, Toshitaka*; Makii, Hiroyuki; Ito, Yuta; Sato, Tetsuya; Tsukada, Kazuaki; Sakaguchi, Satoshi*; Morita, Kosuke*; Watanabe, Yutaka*; et al.
no journal, ,
Solar cells for power generation can be used as a high-energy heavy-ion detector because it has diode characteristics. To utilize the solar cells for fission-fragment measurements, we have investigated the response (energy resolution and pulse height defect) of a solar cell to heavy ions of various nuclides with several different energies.
