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Journal Articles

Ice I$$_{rm c}$$ without stacking disorder by evacuating hydrogen from hydrogen hydrate

Komatsu, Kazuki*; Machida, Shinichi*; Noritake, Fumiya*; Hattori, Takanori; Sano, Asami; Yamane, Ryo*; Yamashita, Keishiro*; Kagi, Hiroyuki*

Nature Communications (Internet), 11(1), p.464_1 - 464_5, 2020/02

 Times Cited Count:6 Percentile:9.79(Multidisciplinary Sciences)

Water freezes below 0$$^{circ}$$C at ambient pressure ordinarily to ice I$$_{rm h}$$, with hexagonal stacking sequence. Under certain conditions, ice with a cubic stacking sequence can also be formed, but ideal ice I$$_{rm c}$$ without stacking-disorder has never been formed until recently. Here we demonstrate a route to obtain ice I$$_{rm c}$$ without stacking-disorder by degassing hydrogen from the high-pressure form of hydrogen hydrate, C$$_{2}$$, which has a host framework isostructural with ice I$$_{rm c}$$. The stacking-disorder free ice I$$_{rm c}$$ is formed from C$$_{2}$$ via an intermediate amorphous or nano-crystalline form under decompression, unlike the direct transformations occurring in ice XVI from neon hydrate, or ice XVII from hydrogen hydrate. The obtained ice I$$_{rm c}$$ shows remarkable thermal stability, until the phase transition to ice I$$_{rm h}$$ at 250 K, originating from the lack of dislocations. This discovery of ideal ice I$$_{rm c}$$ will promote understanding of the role of stacking-disorder on the physical properties of ice as a counter end-member of ice I$$_{rm h}$$.

Journal Articles

Oxidation of silicon carbide in steam studied by laser heating

Pham, V. H.; Nagae, Yuji; Kurata, Masaki; Furumoto, Kenichiro*; Sato, Hisaki*; Ishibashi, Ryo*; Yamashita, Shinichiro

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.670 - 674, 2019/09

Journal Articles

Improving the corrosion resistance of silicon carbide for fuel in BWR environments by using a metal coating

Ishibashi, Ryo*; Tanabe, Shigetada*; Kondo, Takao*; Yamashita, Shinichiro; Nagase, Fumihisa

Proceedings of 2017 Water Reactor Fuel Performance Meeting (WRFPM 2017) (USB Flash Drive), 10 Pages, 2017/09

For improving the corrosion resistance of silicon carbide (SiC) in boiling-water-reactor environments, corrosion-resistant coatings on SiC were evaluated. Due to its hydrogen-generation rate and reaction heat being lower than those of conventional Zircaloy, SiC is expected to be an appropriate material for accident-tolerant fuels. However, there are still many critical issues with the practical application of SiC fuel cladding and fuel channel boxes, one of which is hydrothermal corrosion. Silicon carbide is chemically stable, but silicon oxide formed by oxidation of SiC dissolves in high temperature water. Although the rate of SiC dissolution is very small, the dissolution must be suppressed to comply with regulations for dissolved silica concentration in reactor coolant. In this study, the corrosion behavior of candidate coatings for SiC substrates were evaluated before and after exposure to unirradiated high-purity-water environments.

JAEA Reports

Study of specific energy for evaluation of in situ rock mass properties (Joint research)

Hikima, Ryoichi*; Hirano, Toru*; Yamashita, Masayuki*; Ishiyama, Koji*; Tanno, Takeo*; Sanada, Hiroyuki; Sato, Toshinori

JAEA-Research 2013-040, 51 Pages, 2014/03

JAEA-Research-2013-040.pdf:6.86MB

For the research and development about high-level radioactive waste disposal, it is important to evaluate the mechanical stability of the excavation and the long-term behavior of in situ rock. However, from the limited information such as the bowling core before the excavation, it is difficult to evaluate the mechanical properties of in situ rock containing cracks. For this reason, evaluation of rock properties based on Specific Energy using mechanical data from an excavation machine is carried out. This report describes the results of the joint research carried out in FY 2010 to FY 2012.

Journal Articles

Evaluation of rock properties using a hydraulic rock drill at Mizunami Underground Research Laboratory

Hikima, Ryoichi*; Hirano, Toru*; Yamashita, Masayuki*; Ishiyama, Koji*; Sato, Toshinori; Sanada, Hiroyuki; Tanno, Takeo

Heisei-25 Nendo (2013 Nen) Shigen, Sozai Gakkai Shuki Taikai Koenshu, p.247 - 248, 2013/08

no abstracts in English

Journal Articles

Evaluation of SCCVII tumor cell survival in clamped and non-clamped solid tumors exposed to carbon-ion beams in comparison to X-rays

Hirayama, Ryoichi*; Uzawa, Akiko*; Takase, Nobuhiro*; Matsumoto, Yoshitaka*; Noguchi, Miho; Koda, Kana*; Ozaki, Masakuni*; Yamashita, Kei*; Li, H.*; Kase, Yuki*; et al.

Mutation Research; Genetic Toxicology And Environmental Mutagenesis, 756(1-2), p.146 - 151, 2013/08

 Times Cited Count:16 Percentile:43.63(Biotechnology & Applied Microbiology)

JAEA Reports

The International Atomic Energy Agency Nuclear Energy Management School 2012

Ohgama, Kazuya; Ando, Yoko; Yamaguchi, Mika; Ikuta, Yuko; Shinohara, Nobuo; Murakami, Hiroyuki; Yamashita, Kiyonobu; Uesaka, Mitsuru*; Demachi, Kazuyuki*; Komiyama, Ryoichi*; et al.

JAEA-Review 2013-004, 76 Pages, 2013/05

JAEA-Review-2013-004.pdf:13.53MB

JAEA together with the Japan Nuclear Human Resource Development Network (JN-HRD Net), the University of Tokyo (UT) and the Japan Atomic Industrial Forum (JAIF) cohosted the IAEA-Nuclear Energy Management School in Tokai Village, aiming that Japan will be the center of nuclear HRD in the Asian region. In the school, not only lectures by IAEA experts, but also lectures by Japanese experts and technical visits were included for foreign participants. The school contributed to the internationalization of Japanese young professionals, development of nuclear human resource of other countries, and enhancement of cooperation between IAEA and Japan. Additionally, collaborative relationship within JN-HRD Net was strengthened by the school. In this report, findings obtained during the preparatory work and the school period are reported for future international nuclear HRD activities in Japan.

Journal Articles

Development of a methodology for the characterisation of long-term geosphere evolution, 1; Impacts of natural events and processes on the geosphere evolution of coastal setting, in the case of Horonobe area

Niizato, Tadafumi; Imai, Hisashi*; Maekawa, Keisuke; Yasue, Kenichi; Kurikami, Hiroshi; Shiozaki, Isao*; Yamashita, Ryo*

Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 10 Pages, 2011/10

A critical issue for building confidence in the long-term safety of geological disposal is to demonstrate the stability of the geosphere, taking into account its likely future evolution. This study aims to establish comprehensive techniques for characterising the overall evolution of coastal sites through studying the palaeohydrogeological evolution in the coastal system around the Horonobe area, Hokkaido, northern Japan. Information on natural events and processes related to the palaeohydrogelogical evolution of the area have been integrated into the conceptual models that indicates the temporal and spatial sequences of the events and processes, such as climatic and sea-level changes, palaeogeography, and geomorphological and geological evolution in the area. The groundwater flow simulation, which is based on the conceputualisation of the long-term geosphere evolution, shows the sensitivities of natural events and processes on groundwater flow properties in a coastal setting.

Journal Articles

Application of specific energy for evaluation of in situ rock mass properties; Study plan at Mizunami Underground Research Laboratory

Hikima, Ryoichi; Sato, Toshinori; Sanada, Hiroyuki; Tanno, Takeo; Hirano, Toru*; Yamashita, Masayuki*; Ishiyama, Koji*

Heisei-23 Nendo (2011 Nen) Shigen, Sozai Gakkai Shuki Taikai Koenshu, p.265 - 266, 2011/09

no abstracts in English

Journal Articles

A Neutron crystallographic analysis of phosphate-free ribonuclease A at 1.7 ${AA}$ resolution

Yagi, Daichi*; Yamada, Taro*; Kurihara, Kazuo; Onishi, Yuki*; Yamashita, Masahiro*; Tamada, Taro; Tanaka, Ichiro*; Kuroki, Ryota; Niimura, Nobuo*

Acta Crystallographica Section D, 65(9), p.892 - 899, 2009/09

 Times Cited Count:15 Percentile:19.67(Biochemical Research Methods)

A neutron crystallographic analysis of phosphate-free bovine pancreatic RNase A has been carried out at 1.7 $$AA$$ resolution using the BIX-4 single-crystal diffractometer at the JRR-3 reactor of the Japan Atomic Energy Agency. The high resolution structural model allowed us to determine that His12 acts mainly as a general base in the catalytic process of RNase A. Numerous other distinctive structural features such as the hydrogen positions of methyl groups, hydroxyl groups, prolines, asparagines and glutamines were also determined at 1.7$$AA$$ resolution. The protonation and deprotonation states of all of the charged amino-acid residues allowed us to provide a definitive description of the hydrogen-bonding network around the active site and the H atoms of the key His48 residue. Differences in hydrogen-bond strengths for the $$alpha$$-helices and $$beta$$-sheets were inferred from determination of the hydrogen-bond lengths and the H/D-exchange ratios of the backbone amide H atoms. The correlation between the B factors and hydrogen-bond lengths of the hydration water molecules was also determined.

JAEA Reports

Study on the effects of long-term evolution of geological environment on groundwater flow (Contract research)

Imai, Hisashi*; Yamashita, Ryo*; Shiozaki, Isao*; Urano, Kazuhiko*; Kasa, Hiroyoshi*; Maruyama, Yoshio*; Niizato, Tadafumi; Maekawa, Keisuke

JAEA-Research 2009-001, 116 Pages, 2009/03

JAEA-Research-2009-001.pdf:32.12MB

Evaluation of long-term geological evolution and its impact on groundwater flow is one of the major themes within the frame of Horonobe Underground Research Laboratory Project. For the purpose of development of a groundwater flow modeling methodology considering the effects of long-term geological evolution, following three items were studied: (1) Upgrade of SMS (Sequential Modeling System of geo-environmental evolution impact on groundwater flow) which was developed in 2006 FY; (2) Groundwater flow simulation under more realistic conditions of geological structures and hydrogeological conditions; and (3) Sensitivity study of geo-environmental evolution impacts on groundwater flow. The studies showed following suggestive results. (1) Development of a precise time step setting enabled to narrow the gaps in simulated head between time steps in which the model configuration used to deformed. (2) Several aspects have been found from studies on impact factors such as deposition on pore pressure, recharge rate and difference in density of saline groundwater. For evaluation of pore pressure induced by deposition, it is necessary to model the porosity and permeability variation considering the exceed pore pressure change. The setting of recharge rate during the Ice Age influence the characteristics of groundwater flow in coastal and hilly areas. The density of groundwater is not so influential as topological potential factors, however it is effective for the characteristics of groundwater flow in coastal area and intrusion of recharge water from ground surface. (3) The sensitivity study on faulting characteristics indicated that the two types of fault configuration and the hydraulic conductivity setting considered are not influential on the nature of groundwater flow above the depth of 500 m.

Journal Articles

Anti-FGF23 neutralizing antibodies show the physiological role and structural features of FGF23

Yamazaki, Yuji*; Tamada, Taro; Kasai, Noriyuki*; Urakawa, Itaru*; Aono, Yukiko*; Hasegewa, Hisashi*; Fujita, Toshiro*; Kuroki, Ryota; Yamashita, Takeyoshi*; Fukumoto, Seiji*; et al.

Journal of Bone and Mineral Research, 23(9), p.1509 - 1518, 2008/09

 Times Cited Count:133 Percentile:5.16(Endocrinology & Metabolism)

Fibroblast growth factor (FGF)23 is proposed to play a physiological role in the regulation of phosphate and vitamin D metabolism; deranged circulatory levels of FGF23 cause several diseases with abnormal mineral metabolism. We developed two antibodies (FN1 and FC1) that recognize the N- and C-terminal regions of FGF23, respectively. Both FN1 and FC1 inhibited FGF23 activity in a cell-based Klotho-dependent reporter assay. The present study using neutralizing antibodies confirms that FGF23 is a physiological regulator of phosphate and vitamin D metabolism. Then, we addressed the mechanism of action for these neutralizing antibodies. Structural analysis of the FGF23/FN1-Fab complex revealed that FN1 masked putative FGF receptor-binding sites in the N-terminal domain of FGF23, while biochemical analyses showed that FC1 interfered with the association between FGF23 and Klotho by binding to the C-terminal domain of FGF23. Taken together, our results suggest that the N- and C-terminal domains of FGF23 are responsible for association with cognate FGF receptors and Klotho, respectively, and that these interactions are indispensable for FGF23 activity.

Journal Articles

Analytical study of groundwater flow evolution due to climatic and sealevel change

Kurikami, Hiroshi; Yasue, Kenichi; Niizato, Tadafumi; Imai, Hisashi*; Shiozaki, Isao*; Yamashita, Ryo*

Chikasui Ryudo Kaiseki To Moderuka Ni Kansuru Shimpojium Happyo Rombunshu, p.59 - 66, 2007/01

no abstracts in English

Journal Articles

Ultraslow thermoresponse in hydrogels synthesized with radiation technique

Hiroki, Akihiro; Maekawa, Yasunari; Katakai, Ryoichi*; Yamashita, Takashi*; Muroya, Yusa*; Katsumura, Yosuke*; Yoshida, Masaru

Macromolecules, 39(12), p.4132 - 4137, 2006/06

 Times Cited Count:5 Percentile:81.37(Polymer Science)

Hydrogels, which were synthesized by radiation-induced polymerization and cross-linked reactions of acryloyl-L-proline methyl ester at 0$$^{circ}$$C in aqueous alcohol solutions, exhibit ultraslow volume change in response to variations in external temperature. The shrinking speed of the hydrogels prepared in aqueous alcohol is 1000 times slower than that of the hydrogel prepared in pure water; e.g., the hydrogel prepared in aqueous 1-propanol at 0$$^{circ}$$C shrank in 6 months. It is revealed that the ultraslow thermo-response consists of quick-shrinking and slow-shrinking periods; the ratio between the duration of the two periods depends on the alcohol molecules in the solution. The generation of hydroxyl group at the side chain of the polymer by the coupling reaction between $$alpha$$-hydroxyalkyl radicals of alcohols and $$alpha$$-radical of proline moiety was confirmed by GC/MS analysis of the radiation products. The hydrogen bonding domain containing the hydroxyl groups is proposed to be responsible for the ultraslow response.

JAEA Reports

Study on regionary groundwater flow analysis relevant to the Horonobe underground research program

Imai, Hisashi*; *; Yamashita, Ryo*; *; Amemiya, Kiyoshi*; Chijimatsu, Masakazu*

JNC-TJ1400 2002-004, 357 Pages, 2002/03

JNC-TJ1400-2002-004.pdf:25.69MB

JAEA Reports

Research on evaluation of coupled thermo-hydro-mechanical phenomena against full-scale in-situ experiment

Chijimatsu, Masakazu*; Amemiya, Kiyoshi*; Yamashita, Ryo*

JNC-TJ8400 2002-024, 53 Pages, 2002/02

JNC-TJ8400-2002-024.pdf:4.81MB

no abstracts in English

JAEA Reports

Research on evaluation of coupled thermo-hydro-mechanical phenomena against full-scale in-situ experiment

Chijimatsu, Masakazu*; Amemiya, Kiyoshi*; Yamashita, Ryo*

JNC-TJ8400 2002-023, 147 Pages, 2002/02

JNC-TJ8400-2002-023.pdf:10.91MB

In order to achieve the geological disposal of radioactive waste in safe, it is necessary to ensure the stability of the engineered barrier system (EBS). One of the most important factors for the stability of the EBS is the emplacement technology of the EBS. It is considered that the stability of the EBS is secured by the property emplacement based on the design requirement. In this research, the methods filling the gap between buffer and rock or buffer and over-pack were examined. Bentonite pellets were tested as the filling materials. To research the time-dependent phenomena of bentonite pellets after swelling, permeability tests were conducted with different period. Furthermore, to clarify the effect of test fluid, permeability test was conducted with synthetic seawater to compare the result with that of the test with distilled water. After emplacement of the engineered barrier system, it is expected that the near-field envilonment will be impacted by phenomena such as heat dissipation by conduction and other heat transfer mechanisms, infiltration of groundwater from the surrounding rock in to the engineered barrier system, stress imposed by the overburden pressure and generation of swelling pressure in the buffer due to water infiltration. In order to recognize and evaluate these coupled phenomena, it is necessary to make a confidence of the mathematical models and computer codes based on the information about the in-situ experiments regarding the engineered barrier system. In this research, technical investigations about the in-situ full-scale experiment (called Prototype Repository Project) in Aspo HRL facility by SKB of Sweden were performed.

JAEA Reports

Research on evaluation of coupled thermo-hydro-mechanical behavior in the engineered barrier

Chijimatsu, Masakazu*; Amemiya, Kiyoshi*; Yamashita, Ryo*

JNC-TJ8400 2002-022, 70 Pages, 2002/02

JNC-TJ8400-2002-022.pdf:5.66MB

no abstracts in English

JAEA Reports

Research on evaluation of coupled thermo-hydro-mechanical behavior in the engineered barrier

Chijimatsu, Masakazu*; Amemiya, Kiyoshi*; Yamashita, Ryo*

JNC-TJ8400 2002-021, 258 Pages, 2002/02

JNC-TJ8400-2002-021.pdf:8.82MB

After emplacement of the engineered barrier system (EBS), it is expected that the near-field environment will be impacted by phenomena such as heat dissipation by conduction and other heat transter mechanisms, infiltration of groundwater from the surrounding rock in to the engineered barrier system, stress imposed by the overburden pressure and generation of swelling pressure in the buffer due to water infiltation. In order to recognize and evaluate these coupled thermo-hydro-mechanical (THM) phenomena, it is necessary to make a confidence of the mathematical model and computer codes. Evaluating these coupled THM phenomena is important in order to clarify the initial transient behavior of the EBS within the near field. DECOVALEX project is an international co-opelative project for the DEvelopment of COupled models and their VALidation against EXperiments in nuclear waste isolation and it is significance to participate this project and to apply the code for the validation. Therefore, we tried to apply the developed numerical code against the subjects of DECOVALEX. In the above numerical code, swelling phenomenon is modeled as the function of water potential. However it does not evaluate the experiment results enough. Then, we try to apply the new model.

JAEA Reports

Study on regional ground water flow analysis method in sedimentary rock mass

Imai, Hisashi*; Yamashita, Ryo*; Amemiya, Kiyoshi*; Shiozaki, Isao*

JNC-TJ1410 2001-002, 318 Pages, 2001/08

JNC-TJ1410-2001-002.pdf:34.33MB

75 (Records 1-20 displayed on this page)