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Kusano, Kanya*; Ichimoto, Kiyoshi*; Ishii, Mamoru*; Miyoshi, Yoshizumi*; Yoden, Shigeo*; Akiyoshi, Hideharu*; Asai, Ayumi*; Ebihara, Yusuke*; Fujiwara, Hitoshi*; Goto, Tadanori*; et al.
Earth, Planets and Space (Internet), 73(1), p.159_1 - 159_29, 2021/12
Times Cited Count：7 Percentile：42.16(Geosciences, Multidisciplinary)The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.
Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Takagi, Yasuhiko*; Nakamura, Tomoki*; Hiroi, Takahiro*; Matsuoka, Moe*; et al.
Nature Astronomy (Internet), 5(3), p.246 - 250, 2021/03
Times Cited Count：53 Percentile：96.13(Astronomy & Astrophysics)Here we report observations of Ryugu's subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. However, the strength and shape of the OH feature still suggests that the subsurface material experienced heating above 300 
C, similar to the surface. In contrast, thermophysical modeling indicates that radiative heating does not increase the temperature above 200 C at the estimated excavation depth of 1 m, even if the semimajor axis is reduced to 0.344 au. This supports the hypothesis that primary thermal alteration occurred due to radiogenic and/or impact heating on Ryugu's parent body.
F from 
O
?Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri, A.*; Hwang, S. H.*; et al.
Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05
Times Cited Count：18 Percentile：74.58(Physics, Multidisciplinary)The structure of a neutron-rich F nucleus is investigated by a quasifree (
) knockout reaction. The sum of spectroscopic factors of 
orbital is found to be 1.0 
0.3. The result shows that the O core of F nucleus significantly differs from a free O nucleus, and the core consists of 
35% O
, and 65% excited O. The result shows that the O core of F nucleus significantly differs from a free O nucleus. The result may infer that the addition of the 
proton considerably changes the neutron structure in F from that in O, which could be a possible mechanism responsible for the oxygen dripline anomaly.
Cui, Y.-T.*; Harada, Yoshihisa*; Niwa, Hideharu*; Oshima, Masaharu*; Hatanaka, Tatsuya*; Nakamura, Naoki*; Ando, Masaki*; Yoshida, Toshihiko*; Ishii, Kenji*; Matsumura, Daiju
NanotechJapan Bulletin (Internet), 11(4), 6 Pages, 2018/08
no abstracts in English
high energy resolution X-ray absorption spectroscopyCui, Y.-T.*; Harada, Yoshihisa*; Niwa, Hideharu*; Hatanaka, Tatsuya*; Nakamura, Naoki*; Ando, Masaki*; Yoshida, Toshihiko*; Ishii, Kenji*; Matsumura, Daiju; Oji, Hiroshi*; et al.
Scientific Reports (Internet), 7(1), p.1482_1 - 1482_8, 2017/05
Times Cited Count：21 Percentile：47.80(Multidisciplinary Sciences)
and O/HO adsorption revealed by in situ XAFS and hard X-ray photoelectron spectroscopyCui, Y.*; Harada, Yoshihisa*; Hatanaka, Tatsuya*; Nakamura, Naoki*; Ando, Masaki*; Yoshida, Toshihiko*; Ikenaga, Eiji*; Ishii, Kenji*; Matsumura, Daiju; Li, R.*; et al.
ECS Transactions, 72(8), p.131 - 136, 2016/10
Times Cited Count：1 Percentile：46.41(Electrochemistry)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
Onuki, Toshihiko; Kozai, Naofumi; Sakamoto, Fuminori; Suzuki, Yoshinori*; Yoshida, Takahiro*
Energy Procedia, 39, p.175 - 182, 2013/00
Times Cited Count：4 Percentile：88.59(Energy & Fuels)Accumulation ability of actinides and lanthanides by microorganisms has been studied. In the presence of organic acids, reduced U(IV) by microorganism was still dissolved, and Ce(IV) was present by complexing with Fe-chelate agents, causing Ce anomaly in the adsorption of lanthanides series elements. We introduce the application of these ability to Cs remediation.
and 
-AlO
Onuki, Toshihiko; Yoshida, Takahiro*
Chemistry Letters, 41(1), p.98 - 100, 2012/01
Times Cited Count：10 Percentile：35.40(Chemistry, Multidisciplinary)We have studied the interactions of REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er) - desferrioxamine B (DFO) complexes with cells and with -AlO, at pH 4 - 9. The higher percent adsorption of REEs was obtained at lower pHs on P. Fluorescens cells and at higher pHs on -AlO. Degree of negative anomaly of Ce compared to its neighboring REEs, La(III) and Pr(III) decreased with increasing pH. Thus, the pH dependence of Ce anomaly is predominantly dependent on the stability of Ce(IV)-DFO complex.
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.
Tobita, Kenji; Nishio, Satoshi*; Enoeda, Mikio; Nakamura, Hirofumi; Hayashi, Takumi; Asakura, Nobuyuki; Uto, Hiroyasu; Tanigawa, Hiroyasu; Nishitani, Takeo; Isono, Takaaki; et al.
JAEA-Research 2010-019, 194 Pages, 2010/08
JAEA-Research-2010-019-01.pdf:48.47MBJAEA-Research-2010-019-02.pdf:19.4MB
This report describes the results of the conceptual design study of the SlimCS fusion DEMO reactor aiming at demonstrating fusion power production in a plant scale and allowing to assess the economic prospects of a fusion power plant. The design study has focused on a compact and low aspect ratio tokamak reactor concept with a reduced-sized central solenoid, which is novel compared with previous tokamak reactor concept such as SSTR (Steady State Tokamak Reactor). The reactor has the main parameters of a major radius of 5.5 m, aspect ratio of 2.6, elongation of 2.0, normalized beta of 4.3, fusion out put of 2.95 GW and average neutron wall load of 3 MW/m
. This report covers various aspects of design study including systemic design, physics design, torus configuration, blanket, superconducting magnet, maintenance and building, which were carried out increase the engineering feasibility of the concept.
Tobita, Kenji; Nishio, Satoshi; Enoeda, Mikio; Kawashima, Hisato; Kurita, Genichi; Tanigawa, Hiroyasu; Nakamura, Hirofumi; Honda, Mitsuru; Saito, Ai*; Sato, Satoshi; et al.
Nuclear Fusion, 49(7), p.075029_1 - 075029_10, 2009/07
Times Cited Count：140 Percentile：97.59(Physics, Fluids & Plasmas)Recent design study on SlimCS focused mainly on the torus configuration including blanket, divertor, materials and maintenance scheme. For vertical stability of elongated plasma and high beta access, a sector-wide conducting shell is arranged in between replaceable and permanent blanket. The reactor adopts pressurized-water-cooled solid breeding blanket. Compared with the previous advanced concept with supercritical water, the design options satisfying tritium self-sufficiency are relatively scarce. Considered divertor technology and materials, an allowable heat load to the divertor plate should be 8 MW/m or lower, which can be a critical constraint for determining a handling power of DEMO (a combination of alpha heating power and external input power for current drive).
Onuki, Toshihiko; Yoshida, Takahiro*; Ozaki, Takuo; Kozai, Naofumi; Sakamoto, Fuminori; Nankawa, Takuya; Suzuki, Yoshinori; Francis, A. J.*
Journal of Nuclear Science and Technology, 46(1), p.55 - 59, 2009/01
Times Cited Count：8 Percentile：48.33(Nuclear Science & Technology)Model analysis of the transformation of Pu(VI) in a mixture of a common soil bacterium, Bacillus subtilis, and kaolinite clay was carried out. When we assumed in the model analysis that reduction rate of Pu(V) to Pu(IV) was higher on B. subtilis than on kaolinite, the estimated fractions of Pu in the solution and in the mixture, oxidation states of Pu in the solution and in the mixture were in good agreement with the measured ones. On the contrary, assumption that reduction rate of Pu(V) to Pu(IV) was the same on kaolinite as on 
gave wrong prediction of Pu association with the mixture. These results strongly suggested the electron transfer from the bacteria to Pu(V) on the bacterial cell to be reduced to Pu(IV) during the accumulation of Pu(VI) to the mixture.
Oya, Yasuhisa*; Hirohata, Yuko*; Nakahata, Toshihiko*; Suda, Taichi*; Yoshida, Masashi*; Arai, Takashi; Masaki, Kei; Okuno, Kenji*; Tanabe, Tetsuo*
Fusion Science and Technology, 52(3), p.554 - 558, 2007/10
Times Cited Count：0 Percentile：0.00(Nuclear Science & Technology)To investigate retention characteristics of hydrogen isotopes in the first wall tiles of JT-60U, surface morphology, erosion/deposition profiles and hydrogen isotope retentions were examined by SEM, XPS, TDS and SIMS. It was found that poloidal deuterium retention profile was rather uniform, while the thermal desorption behavior of deuterium was quite different depending on the locations of the tiles. Deuterium retained in the upper first wall, where was covered by thick boron layers with high concentration of B, was desorbed at lower temperature than that in the lower area covered by carbon layers with much less B content. D/H ratio in the first wall tiles was appreciably higher than that observed in the divertor tiles, suggesting the injection of high energy deuteron originating from NBI into the first wall. In addition, the lower temperature of the first wall compared to that of the divertor tiles would prohibit desorption of the implanted deuterium and/or its replacement by subsequent D or H impingement.
Onuki, Toshihiko; Yoshida, Takahiro*; Ozaki, Takuo; Kozai, Naofumi; Sakamoto, Fuminori; Nankawa, Takuya; Suzuki, Yoshinori*; Francis, A. J.
Environmental Science & Technology, 41(9), p.3134 - 3139, 2007/05
Times Cited Count：34 Percentile：57.61(Engineering, Environmental)We investigated the interactions of Pu(VI) with Bacillus subtilis, kaolinite clay, and a mixture of the two to determine and delineate the role of the microbes in regulating the environmental mobility of Pu. The amount of Pu sorbed by B. subtilis increased with time, but had not reached equilibrium in 48 h, whereas equilibrium was attained in kaolinite within 8 h. After 48 h, the oxidation state of Pu in the solutions exposed to B. subtilis and the mixture had changed to Pu(V), whereas the oxidation state of Pu associated with B. subtilis and the mixture was Pu(IV). In contrast, there was no change in the oxidation state of Pu in the solution or on kaolinite after exposure to Pu(VI). SEM-EDS analysis indicated that most of the Pu in the mixture was associated with B. subtilis. These results suggest that Pu(IV) is preferably sorbed to bacterial cells in the mixture, and that Pu(VI) is reduced to Pu(V) and Pu(IV).
Katayama, Hisato*; Kitamura, Harushige*; Mori, Mari*; Nakagawa, Junya*; Yoshida, Takahiro*; Kawai, Toshihiko*; Hase, Yoshihiro; Tanaka, Atsushi
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 94, 2007/02
no abstracts in English
Sekine, Toshihiko; Sawada, Shinichi; Yamaki, Tetsuya; Asano, Masaharu; Suzuki, Akihiro*; Terai, Takayuki*; Yoshida, Masaru
Transactions of the Materials Research Society of Japan, 31(4), p.871 - 874, 2006/12
no abstracts in English
Suzuki, Yoshinori; Nankawa, Takuya; Yoshida, Takahiro*; Ozaki, Takuo; Onuki, Toshihiko; Francis, A. J.; Tsushima, Satoru*; Enokida, Yoichi*; Yamamoto, Ichiro*
Radiochimica Acta, 94(9-11), p.579 - 583, 2006/11
Times Cited Count：21 Percentile：78.89(Chemistry, Inorganic & Nuclear)We examined the reduction behavior of UO
in citrate media at pH 2.0-7.0 by column electrodes. At pH 2.0, UO was reduced to U(IV) through a one-step reduction process, while it was reduced to U(IV) through a two-step reduction process at pH 3.0-5.0. The reduction potential of UO shifted to lower values with an increase in pH from 2.0 to 7.0. At pH 6.0 and 7.0, UO was not reduced to U(IV) completely at the electrode potential above -0.8 V. Ultraviolet-visible spectroscopy and speciation calculation of UO in citrate media indicated that uranium existed as a mainly UO at pH 2-3, and a predominant species at pH 3-5 was [(UO)Cit]
. At pH 5-7, polymeric complexes were present. These findings suggest that the reduction of UO is more difficult by polymerization of UO with citric acid at higher pHs.
Ozaki, Takuo; Kimura, Takaumi; Onuki, Toshihiko; Kirishima, Akira*; Yoshida, Takahiro*; Isobe, Hiroshi*; Francis, A. J.
Environmental Toxicology and Chemistry, 25(8), p.2051 - 2058, 2006/08
Times Cited Count：10 Percentile：23.89(Environmental Sciences)no abstracts in English
Ozaki, Takuo; Suzuki, Yoshinori*; Nankawa, Takuya; Yoshida, Takahiro; Onuki, Toshihiko; Kimura, Takaumi; Francis, A. J.*
Journal of Alloys and Compounds, 408-412, p.1334 - 1338, 2006/02
Times Cited Count：48 Percentile：86.88(Chemistry, Physical)We investigated the interactions of Eu(III) with the common soil bacterium Pseudomonas fluorescens and organic ligands, such as malic acid, citric acid, and a siderophore (DFO). Malic acid formed complexes with Eu(III), but degradation of malic acid was observed when the ratio of malic acid to Eu(III) was high. Citric acid formed a stoichiometric complex with Eu(III) that was not degraded by P. fluorescens. Adsorption of Eu(III) from the DFO complex occurred as a free ion dissociated from DFO and not as the Eu(III)-DFO complex. Time-resolved laser-induced fluorescence spectroscopy analysis showed that adsorption of Eu(III) on P. fluorescens was through a multidentate and predominantly inner-spherical coordination.
