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Journal Articles

Mechanisms responsible for adsorption of molybdate ions on alumina for the production of medical radioisotopes

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:0 Percentile:0(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$$_{4}$$$$^{2-}$$ or AlMo$$_{6}$$O$$_{24}$$H$$_{6}$$$$^{3-}$$) are adsorbed by electrostatic interaction. Alumina dissolves slightly in an acidic solution to form AlMo$$_{6}$$O$$_{24}$$H$$_{6}$$$$^{3-}$$, which is more easily desorbed than MoO$$_{4}$$$$^{2-}$$. 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$$_{4}$$$$^{2-}$$ ions. These findings will assist researchers in engineering more efficient and stable alumina-based adsorbents for molybdenum adsorption used in medical radioisotope ($$^{99}$$Mo/$$^{99m}$$Tc) generators.

Journal Articles

Additive-free hydrothermal leaching method with low environmental burden for screening of strontium in soil

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$$_{2}$$) was adsorbed onto soils for study and ten organic acids were evaluated for leaching Sr from simulated soils under hydrothermal conditions (120 to 200$$^{circ}$$C) 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 150$$^{circ}$$C 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 200$$^{circ}$$C 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 200$$^{circ}$$C 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.

Journal Articles

Supercritical water pretreatment method for analysis of strontium and uranium in soil (Andosols)

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:1 Percentile:48.83(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 $$^{90}$$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$$_{3}$$ 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.

Journal Articles

Experimental study of Gamow-Teller transitions via the high-energy-resolution $$^{18}$$O($$^3$$He,$$t$$)$$^{18}$$F reaction; Identification of the low-energy "super" -Gamow-Teller state

Fujita, Hirohiko*; Fujita, Yoshitaka*; Utsuno, Yutaka; Yoshida, Kenichi*; Adachi, Tatsuya*; Algora, A.*; Csatl$'o$s, M.*; Deaven, J. M.*; Estevez-Aguado, E.*; Guess, C. J.*; et al.

Physical Review C, 100(3), p.034618_1 - 034618_13, 2019/09

AA2019-0318.pdf:1.1MB

 Times Cited Count:8 Percentile:76.2(Physics, Nuclear)

no abstracts in English

Journal Articles

Determination of fusion barrier distributions from quasielastic scattering cross sections towards superheavy nuclei synthesis

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:10 Percentile:67.6(Physics, Multidisciplinary)

Excitation functions of quasielastic scattering cross sections for the $$^{48}$$Ca + $$^{208}$$Pb, $$^{50}$$Ti + $$^{208}$$Pb, and $$^{48}$$Ca + $$^{248}$$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 $$^{48}$$Ca + $$^{208}$$Pb and $$^{50}$$Ti + $$^{208}$$Pb systems coincide with those of the 2n evaporation channel cross sections for the systems, while that of the $$^{48}$$Ca + $$^{248}$$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.

Journal Articles

Study of the reaction $$^{48}$$Ca + $$^{248}$$Cm $$rightarrow$$ $$^{296}$$Lv$$^{ast}$$ at RIKEN-GARIS

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:17 Percentile:77.65(Physics, Multidisciplinary)

The fusion reaction of $$^{48}$$Ca + $$^{248}$$Cm $$rightarrow$$ $$^{296}$$Lv$$^{ast}$$ was studied using the gas-filled recoil-ion separator GARIS at RIKEN. A total of seven $$alpha$$ and spontaneous-fission decay chains were observed, which would originate from the reaction products of the element 116, $$^{292}$$Lv and $$^{293}$$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 $$^{285}$$Cn or the production of the new isotope $$^{294}$$Lv.

Journal Articles

Valence-band electronic structure evolution of graphene oxide upon thermal annealing for optoelectronics

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:10 Percentile:49.68(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 $$sim$$ 600$$^{circ}$$C. 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 500$$^{circ}$$C 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.

Journal Articles

Spin excitations in hole-overdoped iron-based superconductors

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:12 Percentile:67.09(Multidisciplinary Sciences)

Journal Articles

The Fermi chopper spectrometer 4SEASONS at J-PARC

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:79 Percentile:92.75(Physics, Multidisciplinary)

Journal Articles

Charge excitations in the stripe-ordered La$$_{5/3}$$Sr$$_{1/3}$$NiO$$_{4}$$ and La$$_{2-x}$$(Ba,Sr)$$_{x}$$CuO$$_{4}$$ superconducting compounds

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:24 Percentile:75.56(Physics, Multidisciplinary)

Journal Articles

Status of JT-60SA tokamak under the EU-JA broader approach agreement

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:16 Percentile:73.03(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Trends in stimulated Brillouin scattering and optical phase conjugation

Ostermeyer, M.*; Kong, H.-J.*; Kovalev, V. I.*; Harrison, R. G.*; Fotiadi, A. A.*; M$'e$gret, 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:40 Percentile:56.17(Physics, Applied)

Journal Articles

Low-energy spin fluctuations in the ground states of electron-doped Pr$$_{1-x}$$LaCe$$_x$$CuO$$_{4+delta}$$ cuprate superconductors

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:35 Percentile:81.33(Physics, Multidisciplinary)

Low-energy spin fluctuations have been investigated in the electron-doped Pr$$_{1-x}$$LaCe$$_x$$CuO$$_{4+delta}$$ over a wide concentration range of 0.07$$< x <$$0.18, spanning from the antiferromagnetic phase to the heavily overdoped superconducting (SC) phase. The low-energy excitations exhibit commensurate peaks centered at the ($$pi$$, $$pi$$) position for all $$x$$. Our data show that the characteristics of the excitations, such as the relaxation rate and the spin stiffness, decrease with increasing $$x$$ in the SC phase and disappear with the disappearance of superconductivity.

Journal Articles

Performance of stimulated Brillouin scattering used in several heavy fluorocarbons liquids and perfluoropolyether liquids

Yoshida, Hidetsugu*; Nagasawa, Muneyuki*; Okada, Hajime; Fujita, Hisanori*; Nakatsuka, Masahiro*; Park, H.*

Reza Kenkyu, 36(9), p.566 - 572, 2008/09

Journal Articles

Experimental tests of paleoclassical transport

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:27.14(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Progress in the ITER physics basis, 2; Plasma confinement and transport

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

Journal Articles

Numerical method for the stability analysis of ideal MHD modes with a wide range of toroidal mode numbers in tokamaks

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 $$n$$ 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-$$n$$ modes, and that with the ELITE code by comparing the growth rates of intermediate to high $$n$$ modes. With the MARG2D code, the edge stability of JT-60SA, the complementally experiment of ITER, is investigated.

Journal Articles

Incommensurate lattice distortion in the high temperature tetragonal phase of La$$_{2-x}$$(Sr,Ba)$$_{x}$$CuO$$_{4}$$

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:21 Percentile:71.37(Physics, Multidisciplinary)

We report incommensurate diffuse (ICD) scattering appearing in the high-temperature-tetragonal (HTT) phase of La$$_{2-x}$$(Sr,Ba)$$_{x}$$CuO$$_{4}$$ with $$0.07leq xleq 0.20$$ 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$$_6$$ octahedral tilting direction, that is, the diagonal Cu-Cu direction of the CuO$$_2$$ plane, above the LTO-HTT transition temperature $$T_s$$. The temperature dependences of the incommensurability $$delta$$ for all samples scale approximately as $$T/T_s$$, while those of the integrated intensity of the ICD peaks scale as $$(T-T_s)^{-1}$$. These observations together with absence of ICD peaks in the non-superconducting $$x=0.05$$ sample evince a universal incommensurate lattice instability of hole-doped 214 cuprates in the superconducting regime.

Journal Articles

Excitation and decay of the isovector spin-flip giant monopole resonance via the $$^{208}$$Pb($$^{3}$$He,${it tp}$) reaction at 410 MeV

Zegers, R. G. T.*; Abend, H.*; Akimune, Hidetoshi*; Van den Berg, A. M.*; Fujimura, Hisako*; Fujita, Hirohiko*; Fujita, Yoshitaka*; Fujiwara, Mamoru; Gal$`e$s, S.*; Hara, Keigo*; et al.

Nuclear Physics A, 731, p.121 - 128, 2004/02

 Times Cited Count:11 Percentile:57.89(Physics, Nuclear)

no abstracts in English

Journal Articles

Deep level transient spectroscopy study of electron-irradiated CuInSe$$_{2}$$ thin films

Okada, Hiroshi*; Fujita, Naoki*; Lee, H.-S.*; Wakahara, Akihiro*; Yoshida, Akira*; Oshima, Takeshi; Ito, Hisayoshi

Journal of Electronic Materials, 32(9), p.L5 - L8, 2003/09

 Times Cited Count:1 Percentile:12.61(Engineering, Electrical & Electronic)

no abstracts in English

38 (Records 1-20 displayed on this page)