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Yamamoto, Takeshi; Fujita, Manami; Gogami, Toshiyuki*; Harada, Takeshi*; Hayakawa, Shuhei*; Hosomi, Kenji; Ichikawa, Yudai; Ishikawa, Yuji*; Kamata, K.*; Kanauchi, H.*; et al.
EPJ Web of Conferences, 271, p.03001_1 - 03001_5, 2022/11
Fujita, Manami; Hosomi, Kenji; Ishikawa, Yuji*; Kanauchi, H.*; Koike, Takeshi*; Ogura, Yu*; Tamura, Hirokazu; Tanida, Kiyoshi; Ukai, Mifuyu*; Yamamoto, Takeshi
Nuclear Instruments and Methods in Physics Research A, 1042, p.167439_1 - 167439_9, 2022/11
Times Cited Count:2 Percentile:53.91(Instruments & Instrumentation)Fujita, Yoshitaka; Niizeki, Tomotake*; Fukumitsu, Nobuyoshi*; Ariga, Katsuhiko*; Yamauchi, Yusuke*; Malgras, V.*; Kaneti, Y. V.*; Liu, C.-H.*; Hatano, Kentaro*; Suematsu, Hisayuki*; et al.
Bulletin of the Chemical Society of Japan, 95(1), p.129 - 137, 2022/01
Times Cited Count:8 Percentile:76.16(Chemistry, Multidisciplinary)In this work, the mechanisms responsible for the adsorption of molybdate ions on alumina are investigated using in-depth surface analyses carried out on alumina specimens immersed in solutions containing different molybdate ions at different pH values. The obtained results reveal that when alumina is immersed in an acidic solution containing molybdate ions, the hydroxyl groups present on the surface are removed to generate positively charged sites, and molybdate ions (MoO or AlMoOH) are adsorbed by electrostatic interaction. Alumina dissolves slightly in an acidic solution to form AlMoOH, which is more easily desorbed than MoO. Furthermore, the enhancement in the Mo adsorption or desorption property may be achieved by enriching the surface of the alumina adsorbent with many -OH groups and optimizing Mo solution to adsorb molybdate ions on alumina as MoO ions. These findings will assist researchers in engineering more efficient and stable alumina-based adsorbents for molybdenum adsorption used in medical radioisotope (Mo/Tc) generators.
Kato, Takuma*; Nagaoka, Mika; Guo, H.*; Fujita, Hiroki; Aida, Taku*; Smith, R. L. Jr.*
Environmental Science and Pollution Research, 28(39), p.55725 - 55735, 2021/10
Times Cited Count:0 Percentile:0(Environmental Sciences)In this work, hydrothermal leaching was applied to simulated soils (clay minerals vermiculite, montmorillonite, kaolinite) and actual soils (Terunuma, Japan) to generate organic acids with the objective to develop an additive-free screening method for determination of Sr in soil. Stable strontium (SrCl) was adsorbed onto soils for study and ten organic acids were evaluated for leaching Sr from simulated soils under hydrothermal conditions (120 to 200C) at concentrations up to 0.3 M. For strontium-adsorbed vermiculite (Sr-V), 0.1 M citric acid was found to be effective for leaching Sr at 150C and 1 h treatment time. Based on these results, the formation of organic acids from organic matter in Terunuma soil was studied. Hydrothermal treatment of Terunuma soil produced a maximum amount of organic acids at 200C and 0.5 h reaction time. To confirm the possibility for leaching of Sr from Terunuma soil, strontium-adsorbed Terunuma soil (Sr-S) was studied. For Sr-S, hydrothermal treatment at 200C for 0.5 h reaction time allowed 40% of the Sr to be leached at room temperature, thus demonstrating an additive-free method for screening of Sr in soil. The additive-free hydrothermal leaching method avoids calcination of solids in the first step of chemical analysis and has application to both routine monitoring of metals in soils and to emergency situations.
Nagaoka, Mika; Fujita, Hiroki; Aida, Taku*; Guo, H.*; Smith, R. L. Jr.*
Applied Radiation and Isotopes, 168, p.109465_1 - 109465_6, 2021/02
Times Cited Count:0 Percentile:0.01(Chemistry, Inorganic & Nuclear)The radioactivities in the environmental samples are analyzed to monitor the nuclear power facilities. The pretreatment of radioactive nuclides of alpha and beta emitters in the environmental samples is performed with acid to decompose organic matter and extract object nuclide such as Sr, U and Pu. However, the pretreatment methods are time-consuming and used many concentrated acid solutions that are unsafe and hazardous. Therefore, we develop to the new pretreatment method using supercritical water instead of acid. Hydrothermal pretreatment of soils (Andosols) from Ibaraki prefecture (Japan) was used to improve methods for monitoring radioactive Sr and U. Calcined samples were pretreated with subcritical or supercritical water (SCW) followed by extraction with 0.5 M HNO solutions. With SCW pretreatment, recoveries of Sr and U were 70% and 40%, respectively. Experimental recoveries obtained can be described by a linear relationship in water density. The proposed method is robust and can lower environmental burden of routine analytical protocols.
Fujita, Hirohiko*; Fujita, Yoshitaka*; Utsuno, Yutaka; Yoshida, Kenichi*; Adachi, Tatsuya*; Algora, A.*; Csatls, M.*; Deaven, J. M.*; Estevez-Aguado, E.*; Guess, C. J.*; et al.
Physical Review C, 100(3), p.034618_1 - 034618_13, 2019/09
Times Cited Count:12 Percentile:77.09(Physics, Nuclear)no abstracts in English
Tanaka, Taiki*; Narikiyo, Yoshihiro*; Morita, Kosuke*; Fujita, Kunihiro*; Kaji, Daiya*; Morimoto, Koji*; Yamaki, Sayaka*; Wakabayashi, Yasuo*; Tanaka, Kengo*; Takeyama, Mirei*; et al.
Journal of the Physical Society of Japan, 87(1), p.014201_1 - 014201_9, 2018/01
Times Cited Count:18 Percentile:74.47(Physics, Multidisciplinary)Excitation functions of quasielastic scattering cross sections for the Ca + Pb, Ti + Pb, and Ca + Cm reactions were successfully measured by using the gas-filled recoil-ion separator GARIS. Fusion barrier distributions were extracted from these data, and compared with the coupled-channels calculations. It was found that the peak energies of the barrier distributions for the Ca + Pb and Ti + Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the Ca + Cm is located slightly below the 4n evaporation ones. This results provide us helpful information to predict the optimum beam energy to synthesize superheavy nuclei.
Kaji, Daiya*; Morita, Kosuke*; Morimoto, Koji*; Haba, Hiromitsu*; Asai, Masato; Fujita, Kunihiro*; Gan, Z.*; Geissel, H.*; Hasebe, Hiroo*; Hofmann, S.*; et al.
Journal of the Physical Society of Japan, 86(3), p.034201_1 - 034201_7, 2017/03
Times Cited Count:28 Percentile:81.43(Physics, Multidisciplinary)The fusion reaction of Ca + Cm Lv was studied using the gas-filled recoil-ion separator GARIS at RIKEN. A total of seven and spontaneous-fission decay chains were observed, which would originate from the reaction products of the element 116, Lv and Lv. Decay properties observed in the chains are in good agreement with the previously published ones. However, one of the chains showed a discrepancy, indicating the new spontaneous-fission branch in Cn or the production of the new isotope Lv.
Yamaguchi, Hisato*; Ogawa, Shuichi*; Watanabe, Daiki*; Hozumi, Hideaki*; Gao, Y.*; Eda, Goki*; Mattevi, C.*; Fujita, Takeshi*; Yoshigoe, Akitaka; Ishizuka, Shinji*; et al.
Physica Status Solidi (A), 213(9), p.2380 - 2386, 2016/09
Times Cited Count:13 Percentile:52.49(Materials Science, Multidisciplinary)We report valence-band electronic structure evolution of graphene oxide (GO) upon its thermal reduction. The degree of oxygen functionalization was controlled by annealing temperature, and an electronic structure evolution was monitored using real-time ultraviolet photoelectron spectroscopy. We observed a drastic increase in the density of states around the Fermi level upon thermal annealing at 600C. The result indicates that while there is an apparent bandgap for GO prior to a thermal reduction, the gap closes after an annealing around that temperature. This trend of bandgap closure was correlated with the electrical, chemical, and structural properties to determine a set of GO material properties that is optimal for optoelectronics. The results revealed that annealing at a temperature of 500C leads to the desired properties, demonstrated by a uniform and an order of magnitude enhanced photocurrent map of an individual GO sheet compared to an as-synthesized counterpart.
Horigane, Kazumasa*; Kiho, Kunihiro*; Fujita, Kei*; Kajimoto, Ryoichi; Ikeuchi, Kazuhiko*; Ji, S.*; Akimitsu, Jun*; Lee, C. H.*
Scientific Reports (Internet), 6, p.33303_1 - 33303_6, 2016/09
Times Cited Count:14 Percentile:66.32(Multidisciplinary Sciences)Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Mizuno, Fumio; Nakajima, Kenji; Kawamura, Seiko; Yokoo, Tetsuya*; Nakatani, Takeshi; Maruyama, Ryuji; Soyama, Kazuhiko; et al.
Journal of the Physical Society of Japan, 80(Suppl.B), p.SB025_1 - SB025_6, 2011/01
Times Cited Count:102 Percentile:94.01(Physics, Multidisciplinary)Wakimoto, Shuichi; Kimura, Hiroyuki*; Ishii, Kenji; Ikeuchi, Kazuhiko; Adachi, Tadashi*; Fujita, Masaki*; Kakurai, Kazuhisa; Koike, Yoji*; Mizuki, Junichiro; Noda, Yukio*; et al.
Physical Review Letters, 102(15), p.157001_1 - 157001_4, 2009/04
Times Cited Count:25 Percentile:74.98(Physics, Multidisciplinary)Matsukawa, Makoto; Kikuchi, Mitsuru; Fujii, Tsuneyuki; Fujita, Takaaki; Hayashi, Takao; Higashijima, Satoru; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Ide, Shunsuke; Ishida, Shinichi; et al.
Fusion Engineering and Design, 83(7-9), p.795 - 803, 2008/12
Times Cited Count:17 Percentile:72.86(Nuclear Science & Technology)no abstracts in English
Ostermeyer, M.*; Kong, H.-J.*; Kovalev, V. I.*; Harrison, R. G.*; Fotiadi, A. A.*; Mgret, P.*; Kalal, M.*; Slezak, O.*; Yoon, J. W.*; Shin, J. S.*; et al.
Laser and Particle Beams, 26(3), p.297 - 362, 2008/09
Times Cited Count:41 Percentile:55.6(Physics, Applied)Fujita, Masaki*; Matsuda, Masaaki; Lee, S.-H.*; Nakagawa, Masaaki*; Yamada, Kazuyoshi*
Physical Review Letters, 101(10), p.107003_1 - 107003_4, 2008/09
Times Cited Count:37 Percentile:80.76(Physics, Multidisciplinary)Low-energy spin fluctuations have been investigated in the electron-doped PrLaCeCuO over a wide concentration range of 0.070.18, spanning from the antiferromagnetic phase to the heavily overdoped superconducting (SC) phase. The low-energy excitations exhibit commensurate peaks centered at the (, ) position for all . Our data show that the characteristics of the excitations, such as the relaxation rate and the spin stiffness, decrease with increasing in the SC phase and disappear with the disappearance of superconductivity.
Yoshida, Hidetsugu*; Nagasawa, Muneyuki*; Okada, Hajime; Fujita, Hisanori*; Nakatsuka, Masahiro*; Park, H.*
Reza Kenkyu, 36(9), p.566 - 572, 2008/09
Callen, J. D.*; Anderson, J. K.*; Arlen, T. C.*; Bateman, G.*; Budny, R. V.*; Fujita, Takaaki; Greenfield, C. M.*; Greenwald, M.*; Groebner, R. J.*; Hill, D. N.*; et al.
Nuclear Fusion, 47(11), p.1449 - 1457, 2007/11
Times Cited Count:7 Percentile:25.84(Physics, Fluids & Plasmas)no abstracts in English
Doyle, E. J.*; Houlberg, W. A.*; Kamada, Yutaka; Mukhovatov, V.*; Osborne, T. H.*; Polevoi, A.*; Bateman, G.*; Connor, J. W.*; Cordey, J. G.*; Fujita, Takaaki; et al.
Nuclear Fusion, 47(6), p.S18 - S127, 2007/06
no abstracts in English
Aiba, Nobuyuki; Tokuda, Shinji; Fujita, Takaaki; Ozeki, Takahisa; Chu, M. S.*; Snyder, P. B.*; Wilson, H. R.*
Plasma and Fusion Research (Internet), 2, p.010_1 - 010_8, 2007/04
Numerical method for the stability analysis of ideal MHD modes is invented by using the physical model based on the two-dimensional Newcomb equation in combination with the conventional ideal MHD model. The MARG2D code built on this numerical method realizes to analyze the stability of wide range of ideal MHD modes. The validity of MARG2D has been confirmed with the benchmarking test with the DCON code by identifying the stability boundary of low- modes, and that with the ELITE code by comparing the growth rates of intermediate to high modes. With the MARG2D code, the edge stability of JT-60SA, the complementally experiment of ITER, is investigated.
Wakimoto, Shuichi; Kimura, Hiroyuki*; Fujita, Masaki*; Yamada, Kazuyoshi*; Noda, Yukio*; Shirane, Gen*; Gu, G.*; Kim, H.*; Birgeneau, R. J.*
Journal of the Physical Society of Japan, 75(7), p.074714_1 - 074714_6, 2006/07
Times Cited Count:23 Percentile:72.23(Physics, Multidisciplinary)We report incommensurate diffuse (ICD) scattering appearing in the high-temperature-tetragonal (HTT) phase of La(Sr,Ba)CuO with observed by the neutron diffraction technique. For all compositions, a sharp superlattice peak of the low-temperature-orthorhombic (LTO) structure is replaced by a pair of ICD peaks with the modulation vector parallel to the CuO octahedral tilting direction, that is, the diagonal Cu-Cu direction of the CuO plane, above the LTO-HTT transition temperature . The temperature dependences of the incommensurability for all samples scale approximately as , while those of the integrated intensity of the ICD peaks scale as . These observations together with absence of ICD peaks in the non-superconducting sample evince a universal incommensurate lattice instability of hole-doped 214 cuprates in the superconducting regime.