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Journal Articles

Environmental effects on layer-dependent dynamics of Dirac fermions in quasicrystalline bilayer graphene

Zhao, Y.*; Suzuki, T.*; Iimori, T.*; Kim, H.-W.*; Ahn, J. R.*; Horio, Masafumi*; Sato, Yusuke*; Fukaya, Yuki; Kanai, T.*; Okazaki, K.*; et al.

Physical Review B, 105(11), p.115304_1 - 115304_8, 2022/03

 Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Report on participation in the 5th Asian and Oceanic Congress on Radiation Protection (AOCRP-5)

Sakoda, Akihiro; Okazaki, Toru*; Hashizume, Takuya*

Hoken Butsuri (Internet), 53(3), p.197 - 200, 2018/09

This article gives the report on participation in the 5th Asian and Oceanic Congress on Radiation Protection (AOCRP-5), which was held in Melbourne, Australia on between May 20th and 23rd, 2018.

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:45.75(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

Irradiation history of Itokawa regolith material deduced from noble gases in the Hayabusa samples

Nagao, Keisuke*; Okazaki, Ryuji*; Nakamura, Tomoki*; Miura, Yayoi*; Osawa, Takahito; Bajo, Kenichi*; Matsuda, Shintaro*; Ebihara, Mitsuru*; Ireland, T.*; Kitajima, Fumio*; et al.

Science, 333(6046), p.1128 - 1131, 2011/08

 Times Cited Count:118 Percentile:95.65(Multidisciplinary Sciences)

A steroid surface materials record regolith processes and a history of cosmic-ray irradiation. Noble gas isotopes in three rocky grains from Itokawa have been determined. High concentrations of solar He, Ne, and Ar, as high as those in lunar soils, are released at variable temperatures from each sample. The isotopic compositions are essentially identical to those of solar wind but distinguishable in He relative abundance. These noble gas characteristics can be explained by repeated implantation and preferential loss of solar He by removal of weathered He-rich rim on the grain surface through friction among regolith grains on Itokawa. Residence time of regolith materials on Itokawa is alculated to be shorter than 10 Myr, suggesting that regolith materials of small asteroids would escape easily to space.

Journal Articles

Structure of HIV-1 protease in complex with potent inhibitor KNI-272 determined by high-resolution X-ray and neutron crystallography

Adachi, Motoyasu; Ohara, Takashi; Kurihara, Kazuo; Tamada, Taro; Honjo, Eijiro; Okazaki, Nobuo; Arai, Shigeki; Shoyama, Yoshinari; Kimura, Kaname*; Matsumura, Hiroyoshi*; et al.

Proceedings of the National Academy of Sciences of the United States of America, 106(12), p.4641 - 4646, 2009/03

 Times Cited Count:105 Percentile:91.06(Multidisciplinary Sciences)

To further understand the catalytic mechanism and inhibitor recognition of HIV-1 protease, we need to determine the locations of key hydrogen atoms in the catalytic aspartates Asp25 and Asp125. The structure of HIV-1 protease in complex with transition-state analog KNI-272 was determined by combined neutron crystallography at 1.9 ${AA}$ resolution and X-ray crystallography at 1.4 ${AA}$ resolution. The resulting structural data shows that the catalytic residue Asp25 is protonated and that Asp125 is deprotonated. The proton on Asp25 makes a hydrogen bond with the carbonyl group of the allophenylnorstatine group in KNI-272. The deprotonated Asp125 bonds to the hydroxyl proton of Apns. The results provide direct experimental evidence for proposed aspects of the catalytic mechanism of HIV-1 protease; and can therefore contribute substantially to the development of specific inhibitors for therapeutic application.

Oral presentation

Neutron crystal structure analysis of HIV-1 protease complexed with KNI-272

Adachi, Motoyasu; Ohara, Takashi; Kurihara, Kazuo; Tamada, Taro; Honjo, Eijiro; Okazaki, Nobuo; Arai, Shigeki; Shoyama, Yoshinari; Matsumura, Hiroyoshi*; Sugiyama, Shigeru*; et al.

no journal, , 

We have determined a crystal structure of HIV-1 protease by neutron crystallography. The development of HIV-1 protease inhibitors is regarded as a major success of structure-based drug design and contributes to establish highly active anti-retroviral therapy for AIDS. To further understand the catalytic mechanism of HIV-1 protease and interaction between HIV-1 protease and its inhibitor, we have determined the crystal structure of HIV-1 protease in complex with a inhibitor, KNI-272 to 2.3 ${AA}$ resolution by neutron crystallography. Our results indicates that the carbonyl group of allophenylnorstatine (Apns) in KNI-272 forms a significant hydrogen bond with protonated Asp 25, and the hydrogen atom from the hydroxyl group of Apns forms a remarkable hydrogen bond with the deprotonated Asp125. These results show direct evidence that Asp25 provides a proton to carbonyl group of substrate and Asp125 contributes to activate the attacking water molecule as a nucleophile.

Oral presentation

Neutron crystallography for investigation of catalytic mechanism of HIV-1 protease

Adachi, Motoyasu; Ohara, Takashi; Kurihara, Kazuo; Tamada, Taro; Honjo, Eijiro; Okazaki, Nobuo; Arai, Shigeki; Shoyama, Yoshinari; Kimura, Kaname*; Matsumura, Hiroyoshi*; et al.

no journal, , 

HIV-1 protease is a dimeric aspartic protease that cleaves the nascent polyproteins of HIV-1 and plays an essential role in viral replication. To further understand the catalytic mechanism of HIV-1 protease, we have determined the crystal structure of HIV-1 protease in complex with a transition state mimetic tripeptide inhibitor, KNI-272 to 1.9 ${AA}$ resolution by neutron crystallography in combination with 1.4 ${AA}$ resolution X-ray diffraction data. Our results indicates that the carbonyl group of allophenylnorstatine in KNI-272 forms a significant hydrogen bond with protonated Asp 25, and the hydrogen atom from the hydroxyl group of Apns forms a remarkable hydrogen bond with the deprotonated Asp125. These results show direct evidence that Asp25 provides a proton to carbonyl group of substrate and Asp125 contributes to activate the attacking water molecule as a nucleophile.

Oral presentation

Structure analysis of HIV-1 protease by neutron diffraction

Adachi, Motoyasu; Ohara, Takashi; Kurihara, Kazuo; Tamada, Taro; Honjo, Eijiro; Okazaki, Nobuo; Arai, Shigeki; Shoyama, Yoshinari; Matsumura, Hiroyoshi*; Sugiyama, Shigeru*; et al.

no journal, , 

no abstracts in English

Oral presentation

Structure of HIV-1 protease in complex with potent inhibitor KNI-272 determined by neutron crystallography

Adachi, Motoyasu; Ohara, Takashi; Kurihara, Kazuo; Tamada, Taro; Honjo, Eijiro*; Okazaki, Nobuo; Arai, Shigeki; Shoyama, Yoshinari*; Matsumura, Hiroyoshi*; Adachi, Hiroaki*; et al.

no journal, , 

To understand the catalytic mechanism of HIV-1 protease, we have determined the crystal structure of HIV-1 protease in complex with a transition state mimetic inhibitor, KNI-272 by neutron crystallography. Our results indicates that the carbonyl group of allophenylnorstatine in KNI-272 forms a significant hydrogen bond with protonated Asp 25, and the hydrogen atom from the hydroxyl group of allophenylnorstatine forms a remarkable hydrogen bond with the deprotonated Asp125. These results show direct evidence that Asp25 provides a proton to carbonyl group of substrate and Asp125 contributes to activate the attacking water molecule as a nucleophile.

Oral presentation

Crystal structure analysis of HIV-1 protease by complementary use of synchrotron radiation and neutron

Adachi, Motoyasu; Ohara, Takashi; Kurihara, Kazuo; Tamada, Taro; Honjo, Eijiro*; Okazaki, Nobuo; Arai, Shigeki; Shoyama, Yoshinari*; Matsumura, Hiroyoshi*; Sugiyama, Shigeru*; et al.

no journal, , 

In this study, we determined crystal structures of HIV-1 protease complexed with inhibitor by neutron and X-ray crystallography. Finally, we refined the structures to R-factor of 17.3% and free R-factor 20.3% by neutron crystallography and to R-factor of 10.4 % and free R-factor 12.4% by X-ray crystallography. The result shows that Asp 25 residue is protonated and Asp 125 is deprotonated. These information is important to resolve catalytic mechanism and design of new potent inhibitor.

Oral presentation

Structure of HIV-1 protease in complex with potent inhibitor KNI-272 determined by neutron crystallography

Adachi, Motoyasu; Ohara, Takashi; Kurihara, Kazuo; Tamada, Taro; Honjo, Eijiro*; Okazaki, Nobuo; Arai, Shigeki; Shoyama, Yoshinari*; Matsumura, Hiroyoshi*; Adachi, Hiroaki*; et al.

no journal, , 

HIV-1 protease is a dimeric aspartic protease that cleaves the nascent polyproteins of HIV-1 and plays an essential role in viral replication. To further understand the catalytic mechanism of HIV-1 protease, we have determined the crystal structure of HIV-1 protease in complex with a transition state mimetic tripeptide inhibitor, KNI-272 to 1.9 ${AA}$; resolution by neutron crystallography in combination with 1.4 ${AA}$; resolution X-ray diffraction data. Our results indicates that the carbonyl group of allophenylnorstatine (Apns) in KNI-272 forms a significant hydrogen bond with protonated Asp 25, and the hydrogen atom from the hydroxyl group of Apns forms a remarkable hydrogen bond with the deprotonated Asp125. These results show direct evidence that Asp25 provides a proton to carbonyl group of substrate and Asp125 contributes to activate the attacking water molecule as a nucleophile.

Oral presentation

Fault exploration based on the microcrack distribution pattern; The Example of the Tsukiyoshi fault, central Japan

Otani, Tomoyuki*; Okazaki, Kazunari*; Nishimura, Yuki*; Kojima, Satoru*; Kuboshima, Koji; Sasao, Eiji; Tsuruta, Tadahiko

no journal, , 

no abstracts in English

Oral presentation

Fault exploration based on the microcrack distribution pattern; The Example of the Tsukiyoshi fault, central Japan

Otani, Tomoyuki*; Okazaki, Kazunari*; Nishimura, Yuki*; Kojima, Satoru*; Kuboshima, Koji; Sasao, Eiji; Tsuruta, Tadahiko

no journal, , 

no abstracts in English

Oral presentation

The Development of the magnetic order in multiferroic material NdCrTiO$$_{5}$$ revealed by the neutron diffraction study

Kori, Shunsuke*; Igarashi, Taichi*; Okazaki, Ryuji*; Taniguchi, Hiroki*; Tanisaki, Ichiro*; Yasui, Yukio*; Igawa, Naoki; Hoshikawa, Akinori*; Ishigaki, Toru*

no journal, , 

The neutron powder diffraction for the multiferroic material, NdCrTiO$$_{5}$$ has been carried out to investigate the development of the magnetic order in the material. We found the intensities of magnetic peaks increased with decreasing temperature below the transition temperature T$$_{N}$$. We discuss temperate dependence of magnetic moments and the development of magnetic order.

Oral presentation

Fault exploration based on the microcrack distribution pattern; The Example of the Tsukiyoshi fault, central Japan

Otani, Tomoyuki*; Okazaki, Kazunari*; Nishimura, Yuki*; Kojima, Satoru*; Kuboshima, Koji; Tsuruta, Tadahiko; Sasao, Eiji

no journal, , 

no abstracts in English

Oral presentation

Relation of the Tsukiyoshi fault and orientation distribution of microcracks in the borehole MIU-3 core in Mizunami City, Gifu Prefecture

Otani, Tomoyuki*; Yokoi, Kosuke*; Okazaki, Kazunari*; Nishimura, Yuki*; Kojima, Satoru*; Kuboshima, Koji*; Sasao, Eiji

no journal, , 

The orientation of microcracks was measured using the MIU-3 core penetrating the Tsukiyoshi fault to clarify the relation of the microcrack distribution near the fault. Attitude of microcracks in quartz grains in granite are measured under the optical microscope with the universal stage using three perpendicular thin sections. The healed microcracks was probably formed prior to the sealed microcracks. Both healed and sealed microcracks with moderate dip appears near the fault. The distribution of microcracks with moderate dip shows that the preferred orientation of microcracks near the fault is different from that far from the fault. The distribution of the sealed microcracks with moderate dip is narrower than that of the healed microcracks. This shows that the healed microcracks with moderate dip was developed in the intact granite at the earlier stage of the faulting history, and the sealed microcracks was in the weak fault zone which has repeated rupturing and healing at the later.

Oral presentation

The Property of fault zone and fault activity of the Shionohira Fault, Fukushima Prefecture, Japan

Kametaka, Masao*; Sakai, Toru*; Inada, Noriyuki*; Tanaka, Yumiko*; Okazaki, Kazuhiko*; Suzuki, Yuji*; Aoki, Kazuhiro; Tanaka, Yoshihiro; Seshimo, Kazuyoshi; Nakayama, Kazuhiko

no journal, , 

no abstracts in English

Oral presentation

Frictional properties of Shionohira Fault Gouge

Aoki, Kazuhiro; Seshimo, Kazuyoshi; Tanaka, Yoshihiro; Kametaka, Masao*; Sakai, Toru*; Okazaki, Kazuhiko*; Shimamoto, Toshihiko*

no journal, , 

no abstracts in English

Oral presentation

Technical support from the IAEA for improvement of operator's analytical quality for Safeguards

Okazaki, Hiro; Sumi, Mika; Kayano, Masashi; Matsuyama, Kazutomi; Suzuki, Toru

no journal, , 

The Plutonium Fuel Development Center of Japan Atomic Energy Agency (JAEA-PFDC) received Japan's first plutonium in 1966 and commenced research to develop plutonium fuel as a key objective of the Japanese nuclear fuel cycle. Since then fundamental research with plutonium-bearing materials, and the development and fabrication of mixed uranium-plutonium oxide fuels, has been carried out. It is essential that the Operator's measurement quality be continually reviewed and improved for effective and efficient implementation of international Safeguards. In this context, and recognizing the excellent technical cooperation with IAEA measurement experts, JAEA-PFDC has continually worked to improve its measurement system. This paper will present examples of continual measurement improvement by JAEA-PFDC, and will show the benefit and effectiveness of technical support from IAEA towards this goal.

Oral presentation

Introduction of a new thermal storage power station monitored by heat resistant FBG sensors

Nishimura, Akihiko; Takenaka, Yusuke*; Saegusa, Kunio; Hiroki, Seiji; Fujino, Toru*; Amano, Tamio*; Okazaki, Toru*; Yoshida, kazuo*

no journal, , 

no abstracts in English

25 (Records 1-20 displayed on this page)