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Journal Articles

The Surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy

Kitazato, Kohei*; Milliken, R. E.*; Iwata, Takahiro*; Abe, Masanao*; Otake, Makiko*; Matsuura, Shuji*; Arai, Takehiko*; Nakauchi, Yusuke*; Nakamura, Tomoki*; Matsuoka, Moe*; et al.

Science, 364(6437), p.272 - 275, 2019/04

 Times Cited Count:72 Percentile:0.09(Multidisciplinary Sciences)

The near-Earth asteroid 162173 Ryugu, the target of Hayabusa2 sample return mission, is believed to be a primitive carbonaceous object. The Near Infrared Spectrometer (NIRS3) on Hayabusa2 acquired reflectance spectra of Ryugu's surface to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micron was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally- and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

Journal Articles

Transient ionization of the mesosphere during auroral breakup; Arase satellite and ground-based conjugate observations at Syowa Station

Kataoka, Ryuho*; Nishiyama, Takanori*; Tanaka, Yoshimasa*; Kadokura, Akira*; Uchida, Herbert Akihito*; Ebihara, Yusuke*; Ejiri, Mitsumu*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Sato, Kaoru*; et al.

Earth, Planets and Space (Internet), 71, p.9_1 - 9_10, 2019/01

 Times Cited Count:2 Percentile:36.74(Geosciences, Multidisciplinary)

Transient ionization of the mesosphere was detected at around 65 km altitude during the isolated auroral expansion occurred at 2221-2226 UT on June 30, 2017. A general-purpose Monte Carlo particle transport code PHITS suggested that significant ionization is possible in the middle atmosphere due to auroral X-rays from the auroral electrons of $$<$$10 keV.

Journal Articles

Structure analysis and derivation of deformed electron density distribution of polydiacetylene giant single crystal by the combination of X-ray and neutron diffraction data

Tashiro, Koji*; Kusaka, Katsuhiro*; Hosoya, Takaaki*; Ohara, Takashi; Hanesaka, Makoto*; Yoshizawa, Yoshinori*; Yamamoto, Hiroko*; Niimura, Nobuo*; Tanaka, Ichiro*; Kurihara, Kazuo*; et al.

Macromolecules, 51(11), p.3911 - 3922, 2018/06

 Times Cited Count:0 Percentile:100(Polymer Science)

Journal Articles

New precise measurement of muonium hyperfine structure interval at J-PARC

Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 Times Cited Count:2 Percentile:12.39

Journal Articles

New muonium HFS measurements at J-PARC/MUSE

Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12

 Times Cited Count:5 Percentile:6.11

Journal Articles

Chemical form consideration of released fission products from irradiated fast reactor fuels during overheating

Sato, Isamu; Tanaka, Kosuke; Koyama, Shinichi; Matsushima, Kenichi*; Matsunaga, Junji*; Hirai, Mutsumi*; Endo, Hiroshi*; Haga, Kazuo*

Energy Procedia, 82, p.86 - 91, 2015/07

 Times Cited Count:2 Percentile:73.04(Nuclear Science & Technology)

Experiments simulating overheating conditions of fast reactor severe accidents have been previously carried out with irradiated fuels. For the present study, the chemical forms of the fission products (FPs) included in the irradiated fuels were evaluated by thermochemical equilibrium calculations. At temperatures of 2773 K and 2973 K, the most stable forms of Cs, I, Te, Sb, Pd and Ag are gaseous compounds. Cs and Sb detected in the thermal gradient tube (TGT) in the experiments can take gaseous chemical forms of elemental Cs, CsI, Cs$$_{2}$$MoO$$_{4}$$, CsO and elemental Sb, SbO, SbTe, respectively. By comparing experimental results and the estimations, it is seen CsI thermochemically behaves in a manner that traps it in the TGT, while elemental Cs trends to move as fine particles. The moving behavior of the gaseous FPs will obey not only thermochemical principles, but also those of particle dynamics.

Journal Articles

Accurate structure analyses of polymer crystals on the basis of wide-angle X-ray and neutron diffractions

Tashiro, Koji*; Hanesaka, Makoto*; Yamamoto, Hiroko*; Wasanasuk, K.*; Jayaratri, P.*; Yoshizawa, Yoshinori*; Tanaka, Ichiro*; Niimura, Nobuo*; Kusaka, Katsuhiro*; Hosoya, Takaaki*; et al.

Kobunshi Rombunshu, 71(11), p.508 - 526, 2014/11

 Times Cited Count:4 Percentile:77.99(Polymer Science)

The crystal structure analysis of various polymer substances has been reviewed on the basis of wide-angle high-energy X-ray and neutron diffraction data. The progress in structural analytical techniques of polymer crystals have been reviewed at first. The structural models proposed so far were reinvestigated and new models have been proposed for various kinds of polymer crystals including polyethylene, poly(vinyl alcohol), poly(lactic acid) and its stereocomplex etc. The hydrogen atomic positions were also clarified by the quantitative analysis of wide-angle neutron diffraction data, from which the physical properties of polymer crystals have been evaluated theoretically. The bonded electron density distribution has been estimated for a polydiacetylene single crystal on the basis of the so-called X-N method or by the combination of structural information derived from X-ray and neutron diffraction data analysis. Some comments have been added about future developments in the field of structure-property relationship determination.

Journal Articles

Evaluation of performance for IBARAKI biological crystal diffractometer iBIX with new detectors

Kusaka, Katsuhiro*; Hosoya, Takaaki*; Yamada, Taro*; Tomoyori, Katsuaki; Ohara, Takashi; Katagiri, Masaki*; Kurihara, Kazuo; Tanaka, Ichiro*; Niimura, Nobuo*

Journal of Synchrotron Radiation, 20(6), p.994 - 998, 2013/11

 Times Cited Count:23 Percentile:17.49(Instruments & Instrumentation)

The IBARAKI biological crystal diffractometer, iBIX, is a high-performance time-of-flight neutron single-crystal diffractometer for elucidating mainly the hydrogen, protonation and hydration structures of biological macromolecules in various life processes. Since the end of 2008, iBIX has been available to user's experiments supported by Ibaraki University. Since August 2012, an upgrade of the 14-existing detectors has begun and 16 new detectors have been installed for iBIX. The total measurement efficiency of the present diffractometer has been impoved by one order of magnitude from the previous one with the increasing of accelerator power. In December 2012, commissioning of the new detectors was successful, and collection of the diffraction dataset of ribonucrease A as a standard protein was attempted in order to estimate the performance of the upgraded iBIX in comparison with previous results. The resolution of diffraction data, equivalence among intensities of symmetry-related reflections and reliability of the refined structure have been improved dramatically. iBIX is expected to be one of the highest-performance neutron single-crystal diffractometers for biological macromolecules in the world.

Journal Articles

Hydrogen-bond network and pH sensitivity in human transthyretin

Yokoyama, Takeshi*; Mizuguchi, Mineyuki*; Nabeshima, Yuko*; Kusaka, Katsuhiro*; Yamada, Taro*; Hosoya, Takaaki*; Ohara, Takashi; Kurihara, Kazuo; Tanaka, Ichiro*; Niimura, Nobuo*

Journal of Synchrotron Radiation, 20(6), p.834 - 837, 2013/11

 Times Cited Count:4 Percentile:69.76(Instruments & Instrumentation)

Transthyretin (TTR) is a tetrameric protein. TTR misfolding and aggregation are associated with human amyloid diseases. Dissociation of the TTR tetramer is believed to be the rate-limiting step in the amyloid fibril formation cascade. Low pH is known to promote dissociation into monomer and the formation of amyloid fibrils. In order to reveal the molecular mechanisms underlying pH sensitivity and structural stabilities of TTR, neutron diffraction studies were conducted using the IBARAKI Biological Crystal Diffractometer with the time-of-flight method. Crystals for the neutron diffraction experiments were grown up to 2.5 mm$$^{3}$$ for four months. The neutron crystal structure solved at 2.0 ${AA}$ revealed the protonation states of His88 and the detailed hydrogen-bond network depending on the protonation states of His88. This hydrogen-bond network is involved in monomer-monomer and dimer-dimer interactions, suggesting that the double protonation of His88 by acidification breaks the hydrogen-bond network and causes the destabilization of the TTR tetramer. Structural comparison with the X-ray crystal structure at acidic pH identified the three amino acid residues responsible for the pH sensitivity of TTR. Our neutron model provides insights into the molecular stability related to amyloidosis.

Journal Articles

Neutron and X-ray crystallographic analysis of the human $$alpha$$-thrombin-bivalirubin complex at pD 5.0; Protonation states and hydration structure of the enzyme-product complex

Yamada, Taro*; Kurihara, Kazuo; Onishi, Yuki*; Tamada, Taro; Tomoyori, Katsuaki; Masumi, Kenji*; Tanaka, Ichiro*; Kuroki, Ryota; Niimura, Nobuo*

Biochimica et Biophysica Acta; Proteins and Proteomics, 1834(8), p.1532 - 1538, 2013/08

 Times Cited Count:8 Percentile:66.82(Biochemistry & Molecular Biology)

The protonation states and hydration structures of the $$alpha$$-thrombin-bivalirubin complex were studied by joint XN refinement of the single crystal X-ray and neutron diffraction data at resolutions of 1.6 and 2.8 ${AA}$, respectively. The atomic distances were estimated by carrying out X-ray crystallographic analysis at 1.25 ${AA}$ resolution. The complex represents a model of the enzyme-product (EP) complex of $$alpha$$-thrombin. The neutron scattering length maps around the active site suggest that the side chain of H57/H was deuterated. The joint XN refinement showed that occupancies for D$$delta$$1 and D$$epsilon$$2 of H57/H were 1.0 and 0.7, respectively. However, no significant neutron scattering length density was observed around the hydroxyl oxygen O$$gamma$$ of S195/H, which was close to the carboxylic carbon atom of dFPR-COOH. These observations suggest that the O$$gamma$$ atom of S195/H is deprotonated and maintains its nucleophilicity in the EP complex. In addition to the active site, the hydration structures of the S1 subsite and the Exosite I, which are involved in the recognition of bivalirudin, are presented.

Journal Articles

Neutron and X-ray crystallographic analysis of ${it Achromobacter}$ protease I at pD 8.0; Protonation states and hydration structure in the free-form

Onishi, Yuki*; Yamada, Taro*; Kurihara, Kazuo; Tanaka, Ichiro*; Sakiyama, Fumio*; Masaki, Takeharu*; Niimura, Nobuo*

Biochimica et Biophysica Acta; Proteins and Proteomics, 1834(8), p.1642 - 1647, 2013/08

 Times Cited Count:5 Percentile:79.9(Biochemistry & Molecular Biology)

The structure of the free-form of ${it Achromobacter}$ protease I (API) at pD 8.0 was refined by simultaneous use of single crystal X-ray and neutron diffraction data sets to investigate the protonation states of key catalytic residues of the serine protease. Occupancy refinement of the catalytic triad in the active site of API free-form showed that ca. 30% of the imidazole ring of H57 and ca. 70% of the hydroxyl group of S194 were deuterated. This observation indicates that a major fraction of S194 is protonated in the absence of a substrate. The protonation state of the catalytic triad in API was compared with the bovine $$beta$$-trypsin-BPTI complex. The comparison led to the hypothesis that close contact of a substrate with S194 could lower the acidity of its hydroxyl group, thereby allowing H57 to extract the hydrogen from the hydroxyl group of S194. H210, which is a residue specific to API, does not form a hydrogen bond with the catalytic triad residue D113. Instead, H210 forms a hydrogen bond network with S176, H177 and a water molecule. The close proximity of the bulky, hydrophobic residue W169 may protect this hydrogen bond network, and this protection may stabilize the function of API over a wide pH range.

Journal Articles

Investigation of advanced divertor magnetic configuration for DEMO tokamak reactor

Asakura, Nobuyuki; Shinya, Kichiro*; Tobita, Kenji; Hoshino, Kazuo; Shimizu, Katsuhiro; Uto, Hiroyasu; Someya, Yoji; Nakamura, Makoto; Ono, Noriyasu*; Kobayashi, Masahiro*; et al.

Fusion Science and Technology, 63(1T), p.70 - 75, 2013/05

no abstracts in English

Journal Articles

Investigation of advanced divertor magnetic configuration for Demo tokamak reactor

Asakura, Nobuyuki; Shinya, Kichiro*; Tobita, Kenji; Hoshino, Kazuo; Shimizu, Katsuhiro; Uto, Hiroyasu; Someya, Yoji; Nakamura, Makoto; Ono, Noriyasu*; Kobayashi, Masahiro*; et al.

Fusion Science and Technology, 63(1T), p.70 - 75, 2013/05

 Times Cited Count:12 Percentile:22.05(Nuclear Science & Technology)

Design study of poloidal field coil (PFC) locations and current distribution for the advanced divertor in the Demo tokamak reactor was presented. Concept of the super-X divertor (SXD) for Demo reactor has an outer divertor leg longer than the conventional divertor, and it extends outboard to increase both the target wetted area and connection length to the outer target ($$L_{//}$$). Equilibrium calculation code, TOSCA, was developed by introducing two parameters, i.e. super-X null radius ($$R_{SX}$$) and a ratio of the poloidal flux at the super-X null to that at the separatrix ($$f_{SX}$$). Some SXD magnetic configurations with minimal number of PFCs located outside toroidal field coil (TFC) were Demonstrated. Locations of the divertor target were also investigated. It was found that the flux expansion can be increased up to 4-10 depending on the target location and $$f_{SX}$$, and that SXD has an advantage to increase $$L_{//}$$ with $$f_{SX}$$. Thus, the divertor plasma temperature is expected to decrease at the same upstream plasma density. On the other hand, large currents for the divertor PFCs were necessary. Other arrangements of PFCs such as (1) larger $$R_{SX}$$ and (2) inside TFC, can reduce the PFC currents.

Journal Articles

Development of proposed guideline of flow-induced vibration evaluation for hot-leg piping in a sodium-cooled fast reactor

Sakai, Takaaki; Yamano, Hidemasa; Tanaka, Masaaki; Ono, Ayako; Ohshima, Hiroyuki; Kaneko, Tetsuya*; Hirota, Kazuo*; Sago, Hiromi*; Xu, Y.*; Iwamoto, Yukiharu*; et al.

Proceedings of 15th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-15) (USB Flash Drive), 13 Pages, 2013/05

The development of flow-induced vibration evaluation methodology has reached a milestone that separate-effect experimental data under a high Reynolds number regime including swirl and deflected inflow conditions are available for the validation of the methodology. On the other hand, technical standards are desirable to be documented for designers of sodium-cooled fast reactors. From such a background, the documentation of a flow-induced vibration design guideline has been made for the hot-leg piping of Japan sodium-cooled fast reactor. This paper describes the design guideline of the flow-induced vibration evaluation methodology, which has been informed from main separate-effect experiments, as well as supplemental interpretation for the guideline.

Journal Articles

Effect of swirl inflow on flow pattern and pressure fluctuation onto a single-elbow pipe in Japan Sodium-cooled Fast Reactor

Yamano, Hidemasa; Sago, Hiromi*; Hirota, Kazuo*; Hayakawa, Satoshi*; Xu, Y.*; Tanaka, Masaaki; Sakai, Takaaki

Journal of Fluid Science and Technology (Internet), 7(3), p.329 - 344, 2012/09

As part of the development of a flow-induced vibration evaluation methodology for the primary cooling piping in Japan Sodium-cooled Fast Reactor, important factors were discussed in evaluating the flow-induced vibration for the hot-leg piping. To investigate a complex flow near the inlet of the hot-leg piping, a reactor scale numerical analysis was carried out for the reactor upper plenum flow, which was simulated in a 1/10-scale reactor upper plenum experiment. Based on this analysis, experimental conditions on swirl inflow and deflected inflow that were identified as important factors were determined for flow-induced vibration experiments simulating only the hot-leg piping. In this study, the effect of the swirl inflow on flow pattern and pressure fluctuation onto the pipe wall was investigated in a 1/3-scale hot-leg pipe experiment. The experiment has indicated less significant for the pressure fluctuations, while the flow separation region was slightly influenced by the swirl flow. Computational fluid dynamics simulation results also appear in this paper, focusing on its applicability to the hot-leg piping experiments.

Journal Articles

Structure of morpholinium tribromoplumbate C$$_{4}$$H$$_{8}$$ONH$$_{2}$$PbBr$$_{3}$$ studied using single-crystal neutron diffraction

Kawasaki, Takuro; Takahashi, Miwako*; Ohara, Takashi*; Tanaka, Ichiro*; Kusaka, Katsuhiro*; Hosoya, Takaaki*; Yamada, Taro*; Kurihara, Kazuo

Journal of the Physical Society of Japan, 81(9), p.094602_1 - 094602_6, 2012/09

 Times Cited Count:4 Percentile:69.5(Physics, Multidisciplinary)

Journal Articles

In-vessel tritium

Ueda, Yoshio*; Oya, Kaoru*; Ashikawa, Naoko*; Ito, Atsushi*; Ono, Tadayoshi*; Kato, Daiji*; Kawashima, Hisato; Kawamura, Gakushi*; Kenmotsu, Takahiro*; Saito, Seiki*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 88(9), p.484 - 502, 2012/09

no abstracts in English

Journal Articles

Hydrogen-bond network and pH sensitivity in transthyretin; Neutron crystal structure of human transthyretin

Yokoyama, Takeshi*; Mizuguchi, Mineyuki*; Nabeshima, Yuko*; Kusaka, Katsuhiro*; Yamada, Taro*; Hosoya, Takaaki*; Ohara, Takashi*; Kurihara, Kazuo; Tomoyori, Katsuaki*; Tanaka, Ichiro*; et al.

Journal of Structural Biology, 177(2), p.283 - 290, 2012/02

 Times Cited Count:32 Percentile:19.87(Biochemistry & Molecular Biology)

Journal Articles

Study on flow induced vibration evaluation for a large scale JSFR piping, 1; Current status of flow induced vibration evaluation for hot-leg piping

Yamano, Hidemasa; Sakai, Takaaki; Tanaka, Masaaki; Sago, Hiromi*; Hirota, Kazuo*; Xu, Y.*

Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 8 Pages, 2011/05

Journal Articles

X-ray and neutron protein crystallographic analysis of the trypsin-BPTI complex

Kawamura, Kenji*; Yamada, Taro*; Kurihara, Kazuo; Tamada, Taro; Kuroki, Ryota; Tanaka, Ichiro*; Takahashi, Haruyuki*; Niimura, Nobuo*

Acta Crystallographica Section D, 67(2), p.140 - 148, 2011/02

 Times Cited Count:20 Percentile:14.16(Biochemical Research Methods)

168 (Records 1-20 displayed on this page)