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(001) surface using supersonic seeded oxygen molecular beamKatsube, Daiki*; Ono, Shinya*; Takayanagi, Shuhei*; Ojima, Shoki*; Maeda, Motoyasu*; Origuchi, Naoki*; Ogawa, Arata*; Ikeda, Natsuki*; Aoyagi, Yoshihide*; Kabutoya, Yuito*; et al.
Langmuir, 37(42), p.12313 - 12317, 2021/10
Times Cited Count：1 Percentile：6.17(Chemistry, Multidisciplinary)We investigated the oxidation of oxygen vacancies at the surface of anatase TiO(001) using supersonic seeded molecular beam (SSMB) of oxygen. The oxygen vacancies at the top-surface and sub-surface could be eliminated by the supply of oxygen using an SSMB. These results indicate that the interstitial vacancies can be mostly assigned to oxygen vacancies, which can be effectively eliminated by using an oxygen SSMB. Oxygen vacancies are present on the surface of anatase TiO(001) when it is untreated before transfer to a vacuum chamber. These vacancies, which are stable in the as-grown condition, could also be effectively eliminated using the oxygen SSMB.
investigation of radioactive Cs mobility around litter zone in contaminated forest using spent mushroom substrataOnuki, Toshihiko*; Sakamoto, Fuminori; Kozai, Naofumi; Yamasaki, Shinya*; Sasaki, Yoshito; Niizato, Tadafumi
Journal of Nuclear Science and Technology, 56(9-10), p.814 - 821, 2019/09
Times Cited Count：2 Percentile：20.94(Nuclear Science & Technology)We used the spent mushroom substrata (SMSs) which are a kind of by-product after growing edible mushrooms for the 
investigation of radioactive Cs mobility in litter zone in a forest of Fukushima prefecture, Japan. The powder SMS was filled in a plastic net bag of 0.35
0.55 m, then was placed in a forest for 
6 months under three kinds of different conditions without treatment (No treatment), covered with wooden box (With box), and with zeolite placed on upper position of ground surface (With zeolite). We determined the ratio of radioactivity (TF) in the SMS to that of the soil and litter beneath the SMS bags. TFs of "No treatment" and of "With zeolite" were determined between 0.01 and 0.05 for 6 months. On the other hand, TFs of "With box" were lower by one order at 2 and 4 months than those of "No treatment" and of "With zeolite", and nearly the same values as TFs of "No treatment" and "With zeolite" at 6 months. These results clearly indicate that radioactive Cs accumulates in SMS mainly by throughfall. In addition, for a period of several months, fungi contribute to the accumulation of radioactive Cs in the litter zone, even though radioactive Cs was tightly associated with the soil.
Yu, Q.; Onuki, Toshihiko; Tanaka, Kazuya; Kozai, Naofumi; Yamasaki, Shinya*; Sakamoto, Fuminori; Tani, Yukinori*
Geochimica et Cosmochimica Acta, 174, p.1 - 12, 2016/02
Times Cited Count：18 Percentile：58.30(Geochemistry & Geophysics)Although microorganisms possess high sorption capability for lanthanides (Lns), their biological response affecting Lns migration is unclear. We investigated the effects of microbial activity on transformation of Lns by contact of Lns with Aeremonium strictum under metabolically active condition with Mn(II). A biomolecule that specifically complex to Ce(IV) was found to be released from the fungal cell, facilitating the desorption of Ce(IV) from Mn oxide. This biomolecule was not associated with any other trivalent Lns or Fe, which differed from those non-nuclide-specific organic substances released from resting cells, as reported previously.
Nb
)
Ti
]O
crystal near the morphotropic phase boundaryShimizu, Daisuke*; Tsukada, Shinya*; Matsuura, Masato*; Sakamoto, Junya*; Kojima, Seiji*; Namikawa, Kazumichi*; Mizuki, Junichiro; Owada, Kenji
Physical Review B, 92(17), p.174121_1 - 174121_5, 2015/11
Times Cited Count：13 Percentile：49.65(Materials Science, Multidisciplinary)The phase diagram and the relationship between the crystal coherence length and electrical response of Pb[(MgNb)Ti]O (PMN-xPT) near the morphotropic phase boundary (MPB) have been precisely investigated using a single crystal with a Ti composition gradient by synchrotron X-ray diffraction and inelastic light scattering at room temperature. The crystal has two boundaries at Ti compositions of 29.0 mol% and 34.7 mol% which correspond to the phase boundaries between the monoclinic B (MB) and C (MC) phases and between the MC and tetragonal (T) phases, respectively. It is shown that there is a strong negative correlation between the electrical response and the crystal coherence length at the sub-
m scale. The results are explained by the size effects of domains near the MPB.
Onuki, Toshihiko; Jiang, M.*; Sakamoto, Fuminori; Kozai, Naofumi; Yamasaki, Shinya*; Yu, Q.; Tanaka, Kazuya; Utsunomiya, Satoshi*; Xia, X.*; Yange, K.*; et al.
Geochimica et Cosmochimica Acta, 163, p.1 - 13, 2015/08
Times Cited Count：21 Percentile：58.56(Geochemistry & Geophysics)The association of Ce(III) with the microbial cell surface and the formation of Ce phosphate nano-particles are responsible for suppressing the oxidation of Ce(III) to Ce(IV) in the mixtures.
Onuki, Toshihiko; Sakamoto, Fuminori; Yamasaki, Shinya*; Kozai, Naofumi; Shiotsu, Hiroyuki; Utsunomiya, Satoshi*; Watanabe, Naoko*; Kozaki, Tamotsu*
Journal of Environmental Radioactivity, 144, p.127 - 133, 2015/06
Times Cited Count：9 Percentile：26.71(Environmental Sciences)The accumulation of Cs by unicellular fungus of in the presence of minerals has been studied to elucidate the role of microorganisms in the migration of radioactive Cs in the environment. In the presence of minerals in the agar medium, the radioactivity in the yeast cells was in the order of mica 
smectite, illite 
vermiculite, phlogopite, zeolite. This order is inversely correlated to the ratio of the concentration of radioactive Cs between the minerals and the medium solution. These results strongly suggest that the yeast accumulates radioactive Cs competitively with minerals.
Arifi, E.*; Ishimatsu, Koichi*; Iizasa, Shinya*; Namihira, Takao*; Sakamoto, Hiroyuki*; Tachi, Yukio; Kato, Hiroyasu*; Shigeishi, Mitsuhiro*
Construction and Building Materials, 67(Part B), p.192 - 196, 2014/09
Times Cited Count：5 Percentile：25.65(Construction & Building Technology)The Fukushima Dai-ichi Nuclear Plant accident has resulted in a large amount of radioactively contaminated concrete. The possible application of the pulsed power discharge to reduce the amount of contaminated concrete as radioactive waste was investigated. The contaminated concrete was decontaminated by separating contaminated matrix from uncontaminated coarse aggregate under pulsed power discharge process. In this study, a stable Cs isotope was used to simulate radioactively contaminated concrete. As a result, while the volume of reclaimed aggregate from contaminated concrete could be reproduced was up to 60%, nevertheless Cs detected in the reclaimed aggregate was only approximately 3%. Thus most of the Cs were dissolved in water during the discharge process. It is expected that the pulsed power could reduce the contaminated concrete waste by reusing aggregate. Further investigations are requested to test the applicability of this method under the realistic conditions close to the actual waste.
Sakamoto, Fuminori; Onuki, Toshihiko; Kozai, Naofumi; Yamasaki, Shinya; Yoshida, Zenko*; Namba, Kenji*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 12(4), p.257 - 266, 2013/12
no abstracts in English
Yamasaki, Shinya; Shirai, Osamu*; Kano, Kenji*; Kozai, Naofumi; Sakamoto, Fuminori; Onuki, Toshihiko
Chemistry Letters, 42(8), p.819 - 821, 2013/08
Times Cited Count：5 Percentile：24.11(Chemistry, Multidisciplinary)The adsorption behavior of lanthanide ions (except for Pm) on liposomes composed of phosphatidylcholine and cholesterol was examined to understand the interaction between lanthanide ions and the phosphoryl moiety of phospholipids. The adsorption of lanthanide ions increased with an increase in pH under the weakly acidic conditions. Selective adsorption with the local maximum at the Er
ion and local minimum at the Er ion was observed, similar to the selective adsorption of the bacterial cell surface but different from that of orthophosphates. These results indicate that the adsorption of lanthanide on the phospholipid does not result from simple adsorption on orthophosphate functional groups but by the composition and molecular structure of the phospholipid. Our results strongly suggest that liposomes can be used as a simple biomembrane model without any biological activity for the study of adsorption of lanthanide ions.
Kozai, Naofumi; Onuki, Toshihiko; Arisaka, Makoto; Watanabe, Masayuki; Sakamoto, Fuminori; Yamasaki, Shinya; Jiang, M.
Journal of Nuclear Science and Technology, 49(5), p.473 - 478, 2012/05
Times Cited Count：65 Percentile：97.86(Nuclear Science & Technology)Chemical states of radioactive Cs in the contaminated soils by Fukushima Daiichi Nuclear Power Plant accident has been characterized by the desorption experiments using appropriate reagents solutions and size fractionation of the contaminated soils. Approximately 70% of radioactive Cs in the residual fraction were associated with the size fractions larger than the elutriated one, even though mica-like minerals were contained in the elutriated one. These results strongly suggest that radioactive Cs was irreversibly associated with soil components other than mica like minerals in the contaminated soil.
Sakamoto, Fuminori; Onuki, Toshihiko; Kozai, Naofumi; Igarashi, Shosuke*; Yamasaki, Shinya; Yoshida, Zenko; Tanaka, Shunichi*
Nihon Genshiryoku Gakkai Wabun Rombunshi, 11(1), p.1 - 7, 2012/01
The autoradiography analyses of plants and soils collected in Fukushima showed radioactive Cs was distributed on the branch and leaves of trees that were present at the accident and that only small fraction may be transported to new branch and leaves grown after the accident. Radioactive Cs was present on the grass and rice stubble on the soils, but not in the soils beneath the grass and rice stubble, indicating that the radioactive Cs was deposited on the grass and the rice plant. In addition the ratio of the radioactive Cs penetrated into soil layer by weathering was very small for two months after the accident. These results indicate that trees and plant would be the reservoir of the fallout Cs and function for retardation of the fallout Cs migration with rain water.
, AtRev1 and AtPol
in 
-ray-induced mutagenesisNakagawa, Mayu*; Takahashi, Shinya*; Narumi, Issei; Sakamoto, Ayako
Plant Signaling & Behavior (Internet), 6(5), p.728 - 731, 2011/05
, AtRev1 and AtPol in UV light-induced mutagenesis in Arabidopsis![$$^{1[W]}$$](/search/images/ERPHWMK1K3OX0JA.gif)
Nakagawa, Mayu*; Takahashi, Shinya*; Tanaka, Atsushi; Narumi, Issei; Sakamoto, Ayako
Plant Physiology, 155(1), p.414 - 420, 2011/01
Times Cited Count：15 Percentile：43.09(Plant Sciences)no abstracts in English
Takahashi, Shinya*; Nakagawa, Mayu; Tanaka, Atsushi; Narumi, Issei; Shimizu, Kikuo*; Sakamoto, Ayako
JAEA-Review 2008-055, JAEA Takasaki Annual Report 2007, P. 58, 2008/11
no abstracts in English
Takahashi, Shinya*; Sakamoto, Ayako; Tanaka, Atsushi; Shimizu, Kikuo*
Plant Physiology, 145(3), p.1052 - 1060, 2007/11
Times Cited Count：15 Percentile：37.46(Plant Sciences)To clarify the functions of AtREV1 protein, we expressed it in E. coli and purified it. The deoxynucleotidyl transferase activity of the recombinant AtREV1 was examined in a primer extension assay . The recombinant AtREV1 transferred one or two nucleotides to the primer end. Especially, it efficiently inserted dCMP regardless of the opposite base. AtREV1 also inserted a dCMP opposite the apurinic/apyrimidinic (AP) sites, which are physiologically generated or induced by various DNA-damaging agents. However, AtREV1 had no insertion activities against UV-inducible DNA lesions. Although the substrate specificity of AtREV1 was rather narrow in the presence of magnesium ion, it widened in the presence of manganese ion. These results suggest that AtREV1 serves as a deoxycytidyl transferase in plant cells.
Kobayashi, Shinji*; Yoshida, Maiko; Takenaga, Hidenobu; Sakata, Shinya; Kamada, Yutaka; Sakamoto, Yoshiteru; Koide, Yoshihiko; JT-60 Team
Plasma and Fusion Research (Internet), 2, p.S1049_1 - S1049_4, 2007/11
Real-time measurement system of the ion temperature profile has been developed for the feedback (FB) control of the ion temperature gradient (grad-
) with the filter charge exchange recombination spectroscopy (CXRS) system in JT-60U. The rapid analytical scheme without non-linear least square fitting enables us to calculate the ion temperature with four spatial points every 10 ms using a real-time processor system. The FB control experiment of grad- has been demonstrated in ELMy H-mode plasmas by use of the neutral beam injectors having different deposition profiles as actuators. Grad- was controlled to the reference value in the ramp-down phase, however, it did not recovered in the ramp-up phase because the internal transport barrier or transport was affected by the ramp-down of grad-. From the transient response analysis of grad-Ti, the increase in the central using the additional heating was required to recover the deteriorated grad-.
Takenaga, Hidenobu; Oyama, Naoyuki; Asakura, Nobuyuki; Sakamoto, Yoshiteru; Sakata, Shinya
NIFS-PROC-68, p.62 - 65, 2007/09
A mm-wave interferometer has been developed for divertor density measurements in JT-60U. The measurements performed for several plasma phases indicated the feasibility of the system except for the ELMy H-mode phase. In the ELMy H-mode phase, the signal intensity was significantly reduced probably due to refraction. A sharp drop in the divertor plasma density was found during a transition to the ELM free H-mode phase concomitant with a sharp drop in D
emission intensity. Low frequency fluctuation of 1.5 kHz was observed in the divertor plasma density during the quiescent H-mode phase. Feedback control of the divertor plasma density was successfully demonstrated using the mm-wave interferometer as a real-time monitor and the gas-puffing from the bottoms of the W-shaped divertor as an actuator.
and 
in translation synthesisTakahashi, Shinya; Sakamoto, Ayako; Sato, Shusei*; Kato, Tomohiko*; Tabata, Satoshi*; Tanaka, Atsushi
Plant Physiology, 138(2), p.870 - 881, 2005/06
Times Cited Count：50 Percentile：72.08(Plant Sciences)The error-prone DNA translation synthesis (error-prone TLS) has been well characterized in yeast and mammalians, but not in higher plants. Recent finding of an 
-disrupted mutant (
) in Arabidopsis suggested that the error-prone TLS is significant for tolerance to DNA damages in higher plant. To clarify the details of the error-prone TLS in higher plants, we analyzed the T-DNA inserted Arabidopsis mutants defective in or genes, which are thought to be involved in the error-prone TLS system. The mutant (
) was sensitive to UV-B and cisplatin. The mutant (
) was sensitive to long-term UV-B and cisplatin. These results suggest TLS mechanism exists in a higher plant and show that and have important roles in tolerating exposure to DNA-damaging agents, but their function might be redundant.
discharges and real-time control of current profile in JT-60USuzuki, Takahiro; Isayama, Akihiko; Sakamoto, Yoshiteru; Ide, Shunsuke; Fujita, Takaaki; Takenaga, Hidenobu; Luce, T. C.*; Wade, M. R.*; Oikawa, Toshihiro; Naito, Osamu; et al.
Proceedings of 20th IAEA Fusion Energy Conference (FEC 2004) (CD-ROM), 8 Pages, 2004/11
no abstracts in English
Nakata, Kotaro*; Nagasaki, Shinya*; Tanaka, Satoru*; Sakamoto, Yoshiaki; Tanaka, Tadao; Ogawa, Hiromichi
Radiochimica Acta, 90(9-11), p.665 - 669, 2002/12
Times Cited Count：52 Percentile：93.82(Chemistry, Inorganic & Nuclear)Sorption and desorption experiments of Np on magnetite and hematite under aerobic and anaerobic conditions were carried out to investigate the possibility of reduction of Np(V) to Np(IV) on the surfave of iron oxides including Fe(II). The results indicated that Np sorption mechanism on magnetite under anaerobic condition was completely different from that under aerobic condition. The evidence of the presence of Np(IV) on magnetite surface after sorption was obtained from the extraction experiment with TTA/xylene solution.
