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Journal Articles

Spin state of Co$$^{3+} $$ in LaCo$$_{1-x}$$ Rh$$_{x}$$O$$_{3}$$ investigated by structural phenomena

Asai, Shinichiro*; Okazaki, Ryuji*; Terasaki, Ichiro*; Yasui, Yukio*; Kobayashi, Wataru*; Nakao, Akiko*; Kobayashi, Kensuke*; Kumai, Reiji*; Nakao, Hironori*; Murakami, Yoichi*; et al.

Journal of the Physical Society of Japan, 82(11), p.114606_1 - 114606_6, 2013/11

 Times Cited Count:6 Percentile:43.6(Physics, Multidisciplinary)

Neutron and synchrotron X-ray diffraction for LaCo$$_{1-x}$$ Rh$$_{x}$$O$$_{3}$$ have been carried out in order to investigate the structural properties related with the spin state of Co$$^{3+}$$ ions. We have found that the values of the Co(Rh)-O bond lengths in the Co(Rh)O$$_{6}$$ octahedron of LaCo$$_{0.8}$$Rh$$_{0.2}$$O$$_{3}$$ are nearly identical at 10 K. The lattice volume for the Rh$$^{3+}$$ substituted samples decreases with the thermal expansion coefficient similar to that of LaCoO$$_{3}$$ from room temperature, and ceases to decrease around 70 K. These experimental results favor a mixed state consisting of the high-spin state and low-spin state Co$$^{3+}$$ ions, and suggest that the high-spin state Co$$^{3+}$$ ions are thermally excited in addition to those pinned by the substituted Rh$$^{3+}$$ ions.

Journal Articles

Gap junction communication and the propagation of bystander effects induced by microbeam irradiation in human fibroblast cultures; The Impact of radiation quality

Autsavapromporn, N.*; Suzuki, Masao*; Funayama, Tomoo; Usami, Noriko*; Plante, I.*; Yokota, Yuichiro; Muto, Yasuko*; Ikeda, Hiroko; Kobayashi, Katsumi*; Kobayashi, Yasuhiko; et al.

Radiation Research, 180(4), p.367 - 375, 2013/10

 Times Cited Count:57 Percentile:89.96(Biology)

We investigated the role of gapjunction intercellular communication (GJIC) in the propagation of stressful effects in confluent normal human fibroblast cultures wherein only 0.036-0.144% of cells in the population were traversed by primary radiation tracks. Confluent cells were exposed to graded doses from X ray, carbon ion, neon ion or argon ion microbeams in the presence or absence of an inhibitor of GJIC. After 4 h incubation, the cells were assayed for micronucleus (MN) formation. Micronuclei were induced in a greater fraction of cells than expected based on the fraction of cells targeted by primary radiation, and the effect occurred in a dose-dependent manner with any of the radiation sources. Interestingly, the inhibition of GJIC depressed the enhancement of MN formation in bystander cells from cultures exposed to high-LET radiation but not low-LET radiation. The results highlight the important role of radiation quality and dose in the observed effects.

JAEA Reports

Examination on small-sized cogeneration HTGR for developing countries

Sakaba, Nariaki; Tachibana, Yukio; Shimakawa, Satoshi; Ohashi, Hirofumi; Sato, Hiroyuki; Yan, X.; Murakami, Tomoyuki; Ohashi, Kazutaka; Nakagawa, Shigeaki; Goto, Minoru; et al.

JAEA-Technology 2008-019, 57 Pages, 2008/03

JAEA-Technology-2008-019.pdf:8.59MB

The small-sized and safe cogeneration High Temperature Gas-cooled Reactor (HTGR) that can be used not only for electric power generation but also for hydrogen production and district heating is considered one of the most promising nuclear reactors for developing countries where sufficient infrastructure such as power grids is not provided. Thus, the small-sized cogeneration HTGR, named High Temperature Reactor 50-Cogeneration (HTR50C), was studied assuming that it should be constructed in developing countries. Specification, equipment configuration, etc. of the HTR50C were determined, and economical evaluation was made. As a result, it was shown that the HTR50C is economically competitive with small-sized light water reactors.

JAEA Reports

Confirmation tests for fabrication of low density MOX pellet for FBR

Murakami, Tatsutoshi; Suzuki, Kiichi; Hatanaka, Nobuhiro; Hanawa, Yukio; Shinozaki, Masaru; Murakami, Shinichi; Tobita, Yoshimasa; Kawasaki, Takeshi; Kobayashi, Yoshihito; Iimura, Naoto; et al.

JAEA-Technology 2008-017, 97 Pages, 2008/03

JAEA-Technology-2008-017.pdf:2.76MB

Low density MOX pellets for FBR "MONJU" have not been fabricated in Plutonium Fuel Fabricating Facility (PFPF) for these 9 years since completion of the first reload fuel for "MONJU" in 1995. In this period, about 60 % of machines in the pellet fabrication process of PFPF have been replaced with new ones, and fabrication of MOX pellets for "JOYO" has been continued using these machines. Concerning the feed MOX powders for "MONJU", the amount of decay heat has been increased with increase of accumulated Am-241 in this period. In addition, powder characteristic of recycled MOX powder which is one of feed powders, MH-MOX powder, UO$$_{2}$$ powder and recycled MOX powder, was significantly changed by replacing former processing machine used for scrap recycling with improved one. Using MOX powder with increased decay heat and recycled MOX powder processed by new machine, a series of low density MOX pellet fabrication tests were conducted to confirm pellet fabrication conditions for current pellet fabrication machines from October in 2004 to August in 2006. As a conclusion, it was confirmed that low density MOX pellets could be fabricated using these feed powders and replaced machines by adjusting pellet fabrication conditions adequately. This report summarizes the results of a series of low density MOX pellet fabrication tests.

Journal Articles

Devil's flower resulting from a successive charge disproportionation of NaV$$_{2}$$O$$_{5}$$; Understanding of the details of the Ising spin and the competitive interactions which made the devil's flower bloom

Owada, 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 NaV$$_{2}$$O$$_{5}$$, 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 NaV$$_{2}$$O$$_{5}$$. 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.

Journal Articles

Structural relations between two ground states of NaV$$_{2}$$O$$_{5}$$ under high pressure; A Synchrotron X-ray diffraction study

Owada, 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:44.59(Materials Science, Multidisciplinary)

Structural relations between two ground states of the ANNNI (Axial Next Nearest Neighbor Ising) compound NaV$$_{2}$$O$$_{5}$$, C$$_{1/4}$$- and C$$_{0}$$-phases below and above the transition pressure $$P_{rm C}$$ = 1 GPa, were investigated by X-ray diffraction and scattering techniques. The structure of the C$$_{0}$$-phase is well explained by the $$A$$($$A'$$) pattern which is one of four layers ($$AAA'A'$$) of the C$$_{1/4}$$-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 NaV$$_{2}$$O$$_{5}$$, 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.

Journal Articles

Symmetry breaking in the metal-insulator transition of BaVS$$_{3}$$

Inami, Toshiya; Owada, Kenji; Kimura, Hiroyuki*; Watanabe, Masashi*; Noda, Yukio*; Nakamura, Hiroyuki*; Yamasaki, Tomoaki*; Shiga, Masayuki*; Ikeda, Naoshi*; Murakami, Yoichi

Physical Review B, 66(7), p.073108_1 - 073108_4, 2002/08

 Times Cited Count:43 Percentile:84.34(Materials Science, Multidisciplinary)

It has been believed for a long time that the metal-to-insulator (MI) transition of BaVS$$_{3}$$ is not accompanied by any spatial order of spin and lattice. We have carried out x-ray diffraction measurements of BaVS$$_{3}$$ single crystals using laboratory x-ray source as well as synchrotron radiation, and found that superlatiice reflections which double the lattice constant c exist below the transition temperature. The most porbable space group at the low-temperature insulator phase contains two in equivalent vanadium sites and thus a charge disproportionation of the vnadium ions is considered as the main cause of the MI transition.

Journal Articles

Evaluation of core thermal and hydraulic characteristics of HTTR

Maruyama, So; Fujimoto, Nozomu; Sudo, Yukio; Murakami, Tomoyuki*; Fujii, Sadao*

Nucl. Eng. Des., 152, p.183 - 196, 1994/00

 Times Cited Count:14 Percentile:75.32(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Evaluation of hot spot factors for thermal and hydraulic design of HTTR

Maruyama, So; Yamashita, Kiyonobu; Fujimoto, Nozomu; Murata, Isao; Sudo, Yukio; Murakami, Tomoyuki*; Fujii, Sadao*

Journal of Nuclear Science and Technology, 30(11), p.1186 - 1194, 1993/11

 Times Cited Count:7 Percentile:68.63(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Determination of hot spot factors for thermal and hydraulic design of High Temperature Engineering Test Reactor (HTTR)

Maruyama, So; Murakami, Tomoyuki*; Fujii, Sadao*; Fujimoto, Nozomu; Tanaka, Toshiyuki; Sudo, Yukio; Saito, Shinzo

Proc. of the 1st JSME/ASME Joint Int. Conf. on Nuclear Engineering,Vol. 1, p.425 - 430, 1991/00

no abstracts in English

JAEA Reports

Verification of combined thermal-hydraulic and heat conduction analysis code FLOWNET/TRUMP

Maruyama, So; Fujimoto, Nozomu; Kiso, Yoshihiro*; Murakami, Tomoyuki*; Sudo, Yukio

JAERI-M 88-173, 76 Pages, 1988/09

JAERI-M-88-173.pdf:1.78MB

no abstracts in English

JAEA Reports

Disign and evaluation of core flow distribution in High Temperature Engineering Test Reactor(HTTR)

Maruyama, So; Fujimoto, Nozomu; Kiso, Yoshihiro*; Murakami, Tomoyuki*; Takikawa, Noboru*; *; Sudo, Yukio

JAERI-M 88-154, 147 Pages, 1988/08

JAERI-M-88-154.pdf:2.9MB

no abstracts in English

JAEA Reports

Verification of in-vessel thermal and hydraulic analysis code "FLOWNET"

Maruyama, So; Murakami, Tomoyuki*; Kiso, Yoshihiro*; Sudo, Yukio

JAERI-M 88-138, 39 Pages, 1988/07

JAERI-M-88-138.pdf:1.03MB

no abstracts in English

Journal Articles

A Cobalt-accumulator plant, clethra barbinervis sieb. et zucc.

Yamagata, Noboru*; Murakami, Yukio

Nature, 181, p.1808 - 1809, 1958/00

no abstracts in English

Oral presentation

Development of cooling hopper for high heat generating MOX powder

Murakami, Tatsutoshi; Shibanuma, Kimikazu; Hanawa, Yukio; Yamaki, Takao; Suzuki, Mitsuru; Aono, Shigenori

no journal, , 

MOX powder containing organic additives is loaded in a hopper. The hopper has a cooling function to mitigate heat deterioration of organic additives, but its cooling may not be enough for higher order plutonium in the future. So temperature measurement of MOX powder in the hopper was carried out as a preliminarily test for development of cooling hopper.

Oral presentation

Source analysis of radiocaesium in the sediment of Dam-lake Horai using tracer materials in road dust

Saha, M.*; Murakami, Michio*; Yoshimura, Kazuya; Yamashita, Rei*; Sueki, Keisuke*; Koibuchi, Yukio*; Takada, Hideshige*; Onda, Yuichi*

no journal, , 

no abstracts in English

16 (Records 1-16 displayed on this page)
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