Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
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：49 Percentile：96.63(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.
-Na
V
O
Owada, Kenji; Yamauchi, Toru*; Fujii, Yasuhiko*; Ueda, Yutaka*
Physical Review B, 85(13), p.134102_1 - 134102_4, 2012/04
Times Cited Count：10 Percentile：40.14(Materials Science, Multidisciplinary)We have investigated the critical phenomena of the metal-to-insulator (MI) transition of -NaVO. The critical exponent of 0.226(3) and anisotropic diffuse scattering suggest that the MI transition of -NaVO is two-dimensional in nature and that the dimension of the order parameter is not Ising. The non-Ising-like order parameter indicates that the MI transition is not a simple order-disorder type such as that of 
'-NaVO but charge-density-wave-like, where the valence at each V site is continuous and the arrangement is modulated. This closely corresponds to the situation predicted by neutron diffraction measurements and NMR measurements.
Koyama, Shinichi; Suzuki, Tatsuya*; Ozawa, Masaki*; Kurosawa, Kiyoko*; Fujita, Reiko*; Mimura, Hitoshi*; Okada, Ken*; Morita, Yasuji; Fujii, Yasuhiko*
Procedia Chemistry, 7, p.222 - 230, 2012/00
Times Cited Count：2 Percentile：70.03(Chemistry, Analytical)Adv.-ORIENT cycle strategy has been proposed as a basic concept for trinitarian research on separation, transmutation and utilization of nuclides and elements based on FBR fuel cycle. Validation of principal separation method and related safety research were performed from 2006 through 2011 as Phase I program. First, more than 90% of Cs could be recovered from the actual spent fuel [IXC(I) step]. The next is the adsorption of the platinum group metals (PGM), lanthanides, Am and Cm were separated by using a tertiary pyridine-type resin (TPR) as ion exchange steps [IXC(II, III, IV) steps]. The separated PGM metals will be supplied to the electrochemical extraction [CEE step]. As experiment for safety issues, Hastelloy-B at RT and Ta at 90C were confirmed their anti-corrosive in highly concentrated HCl media. Thermo-chemical stability for TPR was verified. Issues to be solved for next phase based on the final results of phase I program.
Koyama, Shinichi; Yamagishi, Isao; Suzuki, Tatsuya*; Ozawa, Masaki*; Fujita, Reiko*; Okada, Ken*; Tatenuma, Katsuyoshi*; Mimura, Hitoshi*; Fujii, Yasuhiko
Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 8 Pages, 2011/12
Effective separation of MA and LLFP, transmutation and utilization were the main directions of Advanced OREINT Cycle project. Study for each integrant technology was concluded as first trial of the project. TPR enabled to separate MA/Ln and then Am/Cm precisely from spent fuel in HCl and HNO
media. CEE method could separate the light PGM and Tc by HCl media. Recovery of Cs from simulated HLLW coul be achieved more than 90 %. In addition, the perspective for next phase was proposed.
Suzuki, Tatsuya*; Nomura, Masao*; Fujii, Yasuhiko*; Ikeda, Atsushi; Takaoka, Toru*; Oguma, Koichi*
Nihon Ion Kokan Gakkai-Shi, 21(3), p.328 - 333, 2010/09
Zinc isotope fractionation in an anion exchange resin has been investigated in hydrochloric acid solution by chromatographic technique. It was found that the heavier zinc isotopes were located disproportionately in the solution phase. The isotope fractionation coefficient was varied from the order of 10
to 10
depending on the hydrochloric acid concentration. The maximum isotope fractionation coefficient was obtained in 1 
hydrochloric acid, while the distribution coefficient of zinc became maximum at around 2 hydrochloric acid. This difference has been further discussed based on the calculated speciation and structural information derived from X-ray absorption spectroscopy.
Ozawa, Masaki; Suzuki, Tatsuya*; Koyama, Shinichi; Yamagishi, Isao; Fujita, Reiko*; Okada, Ken*; Tatenuma, Katsuyoshi*; Mimura, Hitoshi*; Fujii, Yasuhiko*
Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.1117 - 1126, 2009/09
Fujii, Yasuhiko; Arai, Masatoshi
Oyo Butsuri, 78(8), p.758 - 764, 2009/08
The multipurpose facility "J-PARC", jointly built by JAEA and KEK, is used for research in a wide variety of scientific fields such as materials and life sciences using neutrons and muons, nuclear and particle physics using kaons and neutrinos, and nuclear transmutation using neutrons. The 8-year construction period is now over and we are entering a new era of user programs operated by J-PARC Center, also jointly organized by JAEA and KEK. Here we describe in details the world's strongest neutron (JSNS) and muon (MUSE) sources available for users worldwide.
Nagashima, Akira; Fujii, Yasuhiko
Nihon Genshiryoku Gakkai-Shi ATOMO
, 50(11), p.696 - 700, 2008/11
no abstracts in English
Miyazawa, Yutaka*; Sakashita, Tetsuya; Funayama, Tomoo; Hamada, Nobuyuki*; Negishi, Hiroshi*; Kobayashi, Akie*; Kaneyasu, Tomoko*; Oba, Atsushi*; Morohashi, Keita*; Kakizaki, Takehiko*; et al.
Journal of Radiation Research, 49(4), p.373 - 379, 2008/07
Times Cited Count：29 Percentile：64.30(Biology)We examined the role of root cap and elongation zone cells in root hydrotropism using heavy-ion and laser microbeam. Heavy-ion microbeam irradiation of the elongation zone, but not that of the columella cells, significantly and temporary suppressed the development of hydrotropic curvature. However, laser ablation confirmed that columella cells are indispensable for hydrotropism. Systemic heavy-ion broad-beam irradiation suppressed 
expression of 
gene, but not 
gene. Our results indicate that both the root cap and elongation zone have indispensable and functionally distinct roles in root hydrotropism, and that gene expression might be required for hydrotropism in the elongation zone, but not in columella cells.
Fujii, Yasuhiko; Arai, Masatoshi; Kadono, Ryosuke*; Kanaya, Toshiji*; Kamiyama, Takashi*; Niimura, Nobuo*; Nojiri, Hiroyuki*; Noda, Yukio*; Yagi, Takehiko*; Yamada, Kazuyoshi*
Kotai Butsuri, 43(7), p.441 - 450, 2008/07
no abstracts in English
Hasegawa, Makoto; Nakanishi, Takashi*; Fujii, Yasuhiko*; Odaka, Tomohiro*
Hosha Kagaku Nyusu, (17), p.29 - 35, 2008/03
no abstracts in English
O; Understanding of the details of the Ising spin and the competitive interactions which made the devil's flower bloomOwada, Kenji; Fujii, Yasuhiko; Muraoka, Jiro*; Nakao, Hironori*; Murakami, Yoichi*; Noda, Yukio*; Osumi, Hiroyuki*; Ikeda, Naoshi*; Shobu, Takahisa; Isobe, Masahiko*; et al.
Hoshako, 21(2), p.87 - 96, 2008/03
Devil's flower has been found in a temperature-pressure phase diagram of NaVO, which shows a charge disproportionation (CD) at ambient pressure. By a complementary use of an X-ray structural analysis and a resonant X-ray diffraction, which is sensitive to CD, we have investigated the structural relationship between two ground states appeared in lower and higher pressure regions including the charge arrangements. It has been clarified that two equivalent types of charge arrangement in CD correspond to the Ising variable in NaVO. The atomic shifts are regarded as linearly coupled to the Ising spins. The results lead us to the conclusion that it is the first time that the devil's flower blooms in a charge-disproportionation system. The results also lead us to a hypothesis that the competitive interactions between a Ising spins may result from the Ising spin-phonon coupling.
using heavy-ion microbeamMiyazawa, Yutaka*; Sakashita, Tetsuya; Negishi, Hiroshi*; Kobayashi, Akie*; Kaneyasu, Tomoko*; Oba, Atsushi*; Morohashi, Keita*; Kakizaki, Takehiko*; Funayama, Tomoo; Hamada, Nobuyuki*; et al.
JAEA-Review 2007-060, JAEA Takasaki Annual Report 2006, P. 116, 2008/03
We examined the role of root cap and elongation zone cells in root hydrotropism of using heavy ion and laser microbeam. Heavy ion microbeam irradiation of the elongation zone, but not that of the columella cells, significantly and temporarily suppressed the development of hydrotropic curvature. However, laser ablation confirmed that columella cells are indispensable for hydrotropism. Systemic heavy ion broad beam irradiation suppressed de novo expression of INDOLE ACETIC ACID 5 gene. Our results indicate that both the root cap and elongation zone have indispensable and functionally distinct roles in root hydrotropism, and that de novo gene expression might be required for hydrotropism in the elongation zone, but not in columella cells.
Ozawa, Masaki; Suzuki, Tatsuya*; Koyama, Shinichi; Akatsuka, Hiroshi*; Mimura, Hitoshi*; Fujii, Yasuhiko*
Progress in Nuclear Energy, 50(2-6), p.476 - 482, 2008/03
Times Cited Count：38 Percentile：89.97(Nuclear Science & Technology)For the minimization of the ecological burden originated in nuclear fuel recycling, a new R&D strategy was filed as "Adv.-ORIENT cycle". In the context, mutual precise separation of 
-elements, such as minor actinide (MA)/lanthanides (Lns) and Am/Cm, are highly essential for enhancing the MA (
Am) burning. The separation and utilization of rare metal fission products (RMFPs; Ru, Tc, etc) are a new direction in the partitioning and transmutation field. Separation of exothermic nuclides, 
Sr, 
Cs as well as MA, will significantly help to improve the repository tasks. A key separation media are ion exchange chromatography (IXC) by tertiary pyridine resin and a catalytic electrolytic extraction (CEE) by Pd
. On challenging the isotope separation of LLFP, theoretical and laboratory studies were begun for 
Cs, 
Sn in the first priority.
Yamamura, Osamu; Yamamoto, Ryuichi; Nomura, Shigeo; Fujii, Yasuhiko*
Progress in Nuclear Energy, 50(2-6), p.666 - 673, 2008/03
Times Cited Count：4 Percentile：28.95(Nuclear Science & Technology)The application of safeguards to the Tokai Reprocessing Plant(TRP), the world's first reprocessing plant with a sole objective of commercial use, was made on try and error basis because it was the first experience for both the plant and the inspection sides. Through thirty years' faithful cooperation to the IAEA-initiated safeguards program, TRP contributed also to the developments of the international credibility upon the concept of safeguards system of Reprocessing plant in non-nuclear weapon countries. TRP also has been processing over 1,123 ton of spent fuels from the beginning of its active operation in Sept.'77. For 30 years operation of TRP, many technological problems have been overcome to obtain the stable and reliable operation. The process for establishments of maintenance technology in TRP was evaluated through the analysis of significant plant equipment failures reported to the Government and so on. Discussion in this paper is also emphasized that the safeguards system and the maintenance technologies developed by TRP have been applied to the first Rokkasho commercial reprocessing plant (RRP). Furthermore, this operation knowledge base can contribute to the design and construction of the next generation reprocessing plant.
Shamoto, Shinichi; Fujii, Yasuhiko
JAEA-Review 2007-030, 196 Pages, 2007/10
JAEA-Review-2007-030.pdf:31.34MB
The 1st workshop of the Cooperative Research Program on Quantum Beam Technology among RIKEN, NIMS, and JAEA entitled "Quantum Complex Phenomena" was held on June 14, 2007 at Center for Computational Science & e-Systems, Japan Atomic Energy Agency. This workshop is aimed to reveal the mechanism of quantum complex phenomena for the developments of next generation functional materials on the basis of the Cooperative Research Program on Quantum Beam Technology among RIKEN, NIMS, and JAEA. This Cooperative Research Program was concluded on December 20, 2006, in order to lead the research and development of Quantum Beam Technology by the cooperation among RIKEN, NIMS, and JAEA. Along this meaning, this workshop is aimed to introduce own research characteristics for mutual understandings and to discuss starting cooperative research activity for intimate research collaborations. This report includes abstracts and materials of the presentations in the workshop.
O under high pressure; A Synchrotron X-ray diffraction studyOwada, Kenji; Fujii, Yasuhiko; Muraoka, Jiro*; Nakao, Hironori*; Murakami, Yoichi; Noda, Yukio*; Osumi, Hiroyuki*; Ikeda, Naoshi*; Shobu, Takahisa; Isobe, Masahiko*; et al.
Physical Review B, 76(9), p.094113_1 - 094113_10, 2007/09
Times Cited Count：10 Percentile：43.85(Materials Science, Multidisciplinary)Structural relations between two ground states of the ANNNI (Axial Next Nearest Neighbor Ising) compound NaVO, C
- and C
-phases below and above the transition pressure 
= 1 GPa, were investigated by X-ray diffraction and scattering techniques. The structure of the C-phase is well explained by the 
(
) pattern which is one of four layers (
) of the C-phase, however, the amount of the atomic shifts under the conditions 1.6 GPa and 6 K is 27% that under ambient pressure. On the other hand, resonant X-ray scattering showed that the charges are disproportionated under high pressure. Based on these facts, it was concluded that charge disproportionation corresponds to the Ising variable in NaVO, where the atomic shifts are regarded as linearly coupled to the Ising spins. These results lead to the hypothesis that the competitive interactions between the Ising spins may result from the Ising spin-phonon coupling.
Ozawa, Masaki; Koyama, Shinichi; Suzuki, Tatsuya*; Fujita, Reiko*; Mimura, Hitoshi*; Fujii, Yasuhiko*
Proceedings of International Conference on Advanced Nuclear Fuel Cycles and Systems (Global 2007) (CD-ROM), p.451 - 457, 2007/09
To minimize the ecological burden originating in nuclear fuel recycling, a new R&D strategy, Adv.-ORIENT (Advanced Optimization by Recycling Instructive ElemeNTs) cycle, was set forth. A key separation tool is ion exchange chromatography (IXC) by a tertiary pyridine resin having soft donor nitrogen atoms. This method has provided individual recovery of pure Am and Cm products with a Pu/U/Np fraction from irradiated fuel in just a 3-step separation. A catalytic electrolytic extraction (CEE) method by Pd has been employed to separate, purify and fabricate RMFP catalysts. High separation efficiency of RMFP proved hydrochloric acid as a suitable media for their recovery. Different functioned ion exchangers, e.g., ammonium molybdophosphate (AMP), have been investigated for the separation of Cs
. Theoretical and laboratory studies on the isotope separation of LLFPs were begun for 
Se, Sn and Cs.
Koyama, Shinichi; Ozawa, Masaki; Okada, Ken*; Kurosawa, Kiyoko*; Suzuki, Tatsuya*; Fujii, Yasuhiko*
Proceedings of International Conference on Advanced Nuclear Fuel Cycles and Systems (Global 2007) (CD-ROM), p.1530 - 1536, 2007/09
Simplified separation process was proposed based on ion-exchange technique. HCl, HNO and MeOH were used as an eluent. To develop an engineering scale concept, it is indispensable to establish the condition for safety operation. Corrosion test of structural materials in the HCl was performed by using some metals. In this experiment, it was proved that the Ta, Zr, Nb and hastelloy have good endurance to HCl solution. Research of thermal hazard of pyridine-type ion-exchange resin, MeOH and HNO media system was studied in the view point of fire and explosion safety. There is no hazardous reaction between IER/MeOH, HNO media system. In the case of more than 150C, we should pay attention to the exothermic reaction at dried condition NO-IER or IER/HNO media system.
Miyazawa, Yutaka*; Negishi, Hiroshi*; Sakashita, Tetsuya; Kobayashi, Akie*; Kaneyasu, Tomoko*; Oba, Atsushi*; Funayama, Tomoo; Wada, Seiichi*; Hamada, Nobuyuki*; Kakizaki, Takehiko; et al.
JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 119, 2007/02
