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Hirohata, Atsufumi*; Lloyd, D. C.*; Kubota, Takahide*; Seki, Takeshi*; Takanashi, Koki; Sukegawa, Hiroaki*; Wen, Z.*; Mitani, Seiji*; Koizumi, Hiroki*
IEEE Access, 11, p.117443 - 117459, 2023/10
Times Cited Count：2 Percentile：13.47(Computer Science, Information Systems)Wei, D.*; Gong, W.; Tsuru, Tomohito; Lobzenko, I.; Li, X.*; Harjo, S.; Kawasaki, Takuro; Do, H.-S.*; Bae, J. W.*; Wagner, C.*; et al.
International Journal of Plasticity, 159, p.103443_1 - 103443_18, 2022/12
Times Cited Count：77 Percentile：99.57(Engineering, Mechanical)
SGo, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Aoi, Nori*; Azaiez, F.*; Furutaka, Kazuyoshi; Hatsukawa, Yuichi; Kimura, Atsushi; Kisamori, Keiichi*; Kobayashi, Motoki*; et al.
Physical Review C, 103(3), p.034327_1 - 034327_8, 2021/03
Times Cited Count：4 Percentile：48.14(Physics, Nuclear)SGo, Shintaro*; Ideguchi, Eiji*; Yokoyama, Rin*; Kobayashi, Motoki*; Kisamori, Keiichi*; Takaki, Motonobu*; Miya, Hiroyuki*; Ota, Shinsuke*; Michimasa, Shinichiro*; Shimoura, Susumu*; et al.
JPS Conference Proceedings (Internet), 6, p.030005_1 - 030005_4, 2015/06
Oguri, Hidetomo; Hasegawa, Kazuo; Ito, Takashi; Chishiro, Etsuji; Hirano, Koichiro; Morishita, Takatoshi; Shinozaki, Shinichi; Ao, Hiroyuki; Okoshi, Kiyonori; Kondo, Yasuhiro; et al.
Proceedings of 11th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.389 - 393, 2014/10
no abstracts in English
c characteristics in PIT wires based on BaFe
As with different substitutionsTamegai, Tsuyoshi*; Pyon, S.*; Ding, Q. P.*; Inoue, Hiroshi*; Kobayashi, Hiroki*; Tsuchiya, Yuji*; Sun, Y.*; Kajitani, Hideki; Koizumi, Norikiyo
Journal of Physics; Conference Series, 507(2), p.022041_1 - 022041_4, 2014/05
Times Cited Count：3 Percentile：75.69(Engineering, Electrical & Electronic)The author studied the effect of chemical compound for superconducting performance (c) of iron-based superconductors. As a result, it was revealed that BaFeAs showed high Jc. And more, BaFeAs showed higer c such as 32,000A/cm
(4.2K) by being applied of 120 MPa of hot isostatic pressure (HIP). Thus, higher c performance could be achieved.
As by 320 MeV Au irradiation in single crystals and by high-pressure sintering in powder-in-tube wiresPyon, S.*; Taen, Toshihiro*; Otake, Fumiaki*; Tsuchiya, Yuji*; Inoue, Hiroshi*; Akiyama, Hiroki*; Kajitani, Hideki; Koizumi, Norikiyo; Okayasu, Satoru; Tamegai, Tsuyoshi*
Applied Physics Express, 6(12), p.123101_1 - 123101_4, 2013/12
Times Cited Count：22 Percentile：64.99(Physics, Applied)We demonstrate a large enhancement of critical current density (
) up to 1.0 
10
A/cm at 5 K under self-field in (Ba,K)FeAs single crystals by irradiating 320 MeV Au ions. With the very promising potential of this material in mind, we have fabricated a (Ba,K)FeAs superconducting wire through a powder-in-tube method combined with the hot isostatic pressing technique, whose effectiveness has been proven in industrial Bi2223 tapes. The Jc in the wire at 4.2 K has reached 37 kA/cm under self-field and 3.0 kA/cm at 90 kOe. Magneto-optical imaging of the wire confirmed the large intergranular Jc in the wire core.
Hasegawa, Shin; Takahashi, Shuichi*; Iwase, Hiroki*; Koizumi, Satoshi; Onuma, Masato*; Maekawa, Yasunari
Polymer, 54(12), p.2895 - 2900, 2013/05
Times Cited Count：9 Percentile：27.99(Polymer Science)Radiation-induced graft polymerization of sulfo-containing styrene derivatives into crystalline poly(ether ether ketone) (PEEK) substrates was carried out to prepare thermally and mechanically stable polymer electrolyte membranes based on an aromatic hydrocarbon polymer, so-called "super-engineering plastics". Graft polymerization of the sulfo-containing styrene, ethyl 4-styrenesulfonate (E4S) into PEEK substrates with degrees of crystallinity (DC) of 11 - 26% gradually progressed, achieving a grafting degree of more than 50% after 72 hours, whereas graft polymerization of the substrates with DC above 26% did not proceed. When morphological change in these films were measured by SAXS, PEEK films with DC larger than 26% showed a new peak at d=14 nm, corresponding to lamella structure. Thus, the suppression of graft polymerization of PEEK films with DC above 26% was due to obstruct of monomer diffusion by the formation of the oriented lamella structure.
rangeIwase, Hiroki*; Sawada, Shinichi; Yamaki, Tetsuya; Koizumi, Satoshi; Onuma, Masato*; Maekawa, Yasunari
Macromolecules, 45(22), p.9121 - 9127, 2012/11
Times Cited Count：19 Percentile：53.01(Polymer Science)Fundamental understanding of the structure-property relationship of polymer electrolyte membranes (PEM) is prerequisite for a material design satisfying PEM performance requirement. Small-angle scattering in a wide- range was observed by focusing small-angle neutron scattering (FSANS), small-angle neutron scattering (SANS), and small-angle X-ray scattering (SAXS). The hierarchical structure of the PEM was characterized as being composed of conducting layers (graft domains) in lamellar stacks with 48-57 nm spacing on the surfaces of 480 nm diameter crystallites and ultra-small structures with a 1.7 nm correlation distance of the sulfonic acid groups in the conducting layers. From the change in the SAXS profiles as a function of grafting degrees, it was revealed that the graft domains around the crystallites were connected with the adjoining domains and thus, the PEMs with a higher degree of grafting had conductivity higher than that of Nafion.
Hasegawa, Shin; Chen, J.; Koshikawa, Hiroshi; Iwase, Hiroki*; Koizumi, Satoshi; Onuma, Masato*; Maekawa, Yasunari; Iwase, Hiroki*
Proceedings of 12th International Conference on Radiation Curing in Asia (RadTech Asia 2011) (Internet), p.238 - 239, 2011/06
Radiation-induced graft polymerization of sulfo-containing styrene derivatives into crystalline poly(ether ether ketone) (PEEK) substrates was carried out to prepare thermally and mechanically stable polymer electrolyte membranes based on an aromatic hydrocarbon polymer, so-called "super-engineering plastics". Graft polymerization of the sulfo-containing styrene, ethyl 4-styrenesulfonate (E4S) into PEEK substrates with degrees of crystallinity (DC) of 11 - 26% gradually progressed, achieving a grafting degree of more than 50% after 72 hours, whereas graft polymerization of the substrates with DC above 26% did not proceed. When morphological change in these films were measured by SAXS, PEEK films with DC larger than 26% showed a new peak at d=14 nm, corresponding to lamella structure. Thus, the suppression of graft polymerization of PEEK films with DC above 26% was due to obstruct of monomer diffusion by the formation of the oriented lamella structure.
Hasegawa, Shin; Takahashi, Shuichi*; Iwase, Hiroki*; Koizumi, Satoshi; Morishita, Norio; Sato, Ken*; Narita, Tadashi*; Onuma, Masato*; Maekawa, Yasunari
Polymer, 52(1), p.98 - 106, 2011/01
Times Cited Count：48 Percentile：80.90(Polymer Science)Radiation-induced graft polymerization of sulfo-containing styrene derivatives into poly(ether ether ketone) (PEEK) substrates was carried out to prepare thermally and mechanically stable polymer electrolyte membranes based on an aromatic hydrocarbon polymer. Graft polymerization of ethyl 4-styrenesulfonate into a 32% crystallinity degree PEEK substrate hardly progressed, whereas graft polymerization into 11% PEEK substrate gradually progressed, achieving a grafting degree of more than 50% after 72 h. From Electron Spin Resonance analysis of irradiated PEEK films, it apparent the graft polymerization initiate from the phenoxy radicals. Small-angle X-ray scattering and small-angle neutron scattering observations clearly showed that the graft-type PEEK membranes possessed ion channel domains with the average distance of 13 nm, being larger than that of Nafion. Furthermore, there was a micro-structure in the ion channels with the average distance of 1.8 nm.
Iwase, Hiroki*; Sawada, Shinichi; Yamaki, Tetsuya; Maekawa, Yasunari; Koizumi, Satoshi
International Journal of Polymer Science, 2011(2011), p.301807_1 - 301807_7, 2011/00
Times Cited Count：12 Percentile：37.14(Polymer Science)Preirradiation graft polymerization of styrene in a poly(tetrafluoroethylene) (PTFE) film was examined by time-resolved small-angle neutron scattering (SANS). A crosslinked PTFE film, thickness of which is about 50
m, was irradiated by 
-ray and immersed in a mixed solvent of styrene monomer and toluene. SANS elucidated that graft polymerization proceeds by two reaction processes (I) and (II). In process (I) at 0
200 min, graft polymerization occurs at an interface between crystalline and amorphous PTFE domains and the grafted polystyrene segregates from PTFE, forming a thin layer with a sharp interface. In process (II) at 200600 min, grafted PS layer starts to bridge between crystalline domains. At the end of process (II), 40% of total crystalline PTFE domain is covered by the grafted PS chains.
Iwase, Hiroki; Koizumi, Satoshi; Iikura, Hiroshi; Matsubayashi, Masahito; Yamaguchi, Daisuke; Maekawa, Yasunari; Hashimoto, Takeji
Nuclear Instruments and Methods in Physics Research A, 605(1-2), p.95 - 98, 2009/06
Times Cited Count：34 Percentile：88.95(Instruments & Instrumentation)We constructed an in-situ and simultaneous observation method as a result of combination between ultra-small-angle neutron scattering and neutron imaging (radiography). With this novel technique, we are able to visualize water distribution or transportation, occurring from micro to macro length scales in a polymer electrolyte fuel cell (PEFC). At a sample position of SANS-J-II at JRR-3, we installed a neutron imaging camera in order to construct an in-situ and simultaneous observation method by USANS and neutron imaging with monochromatized cold neutrons. In addition, in order to selectively observe MEA in a running PEFC by using the in-situ and simultaneous observation method, we need to replace carbon separators which cause strong small-angle scattering as a noise. To reduce this strong background, we replaced the carbon separators with the aluminium ones. As a result, the background scattering was minimized (1/10) as compared to before.
Koizumi, Satoshi; Zhao, Y.; Tomita, Yoko*; Kondo, Tetsuo*; Iwase, Hiroki; Yamaguchi, Daisuke; Hashimoto, Takeji
European Physical Journal E, 26(1-2), p.137 - 142, 2008/05
Times Cited Count：57 Percentile：86.19(Chemistry, Physical)no abstracts in English
observation from 10
to 2.0
using a focusing and polarized neutron small-angle scattering spectrometer, SANS-J-IIIwase, Hiroki; Koizumi, Satoshi; Suzuki, Junichi; Oku, Takayuki; Sasao, Hajime*; Tanaka, Hirokazu*; Shimizu, Hirohiko*; Hashimoto, Takeji
Journal of Applied Crystallography, 40(s1), p.s414 - s417, 2007/04
Times Cited Count：17 Percentile：82.01(Chemistry, Multidisciplinary)In order to extend an upper q-limit larger, high-angle He sub-detectors were installed on focusing and polarized neutron small-angle scattering spectrometer (SANS-J-II) at JRR-3, Tokai. Consequently, its upper q-limit was improved from 0.2 to 2. To quantitatively discriminate spin incoherent scattering from hydrogen or to perform nuclear spin polarization contrast variation, a remanent supermirror analyser is also available on the high-angle sub detector. By combining a focusing ultra-small angle scattering, realized by compound and/or magnetic lens and high resolution area detector, SANS-J-II is able to cover from 310
to 2 (four order of magnitude of q), which profits to investigate hierarchically ordered system, found widely in hard, soft and bio-materials.
Oku, Takayuki; Iwase, Hiroki; Shinohara, Takenao; Yamada, Satoru; Hirota, Katsuya*; Koizumi, Satoshi; Suzuki, Junichi; Hashimoto, Takeji; Shimizu, Hirohiko
Journal of Applied Crystallography, 40(s1), p.s408 - s413, 2007/04
Times Cited Count：30 Percentile：90.23(Chemistry, Multidisciplinary)Measuring efficiency and/or angular resolution of small-angle neutron scattering experiments can be improved by focusing neutrons on a detector plane. Thus, a magnetic focusing lens (MNL) have been installed into the SANS instrument, SANS-J-II, of JRR-3 in AEA for the focusing-geometry SANS (FSANS) experiments. The MNL is an extended Halbach-type permanent sextupole magnet. The inner diameter and length of the MNL are 35 mm and 1200 mm, respectively. As the MNL functions as the focusing lens only for the polarized neutron with positive polarity, the incident neutron polarization is set positive by using the supermirror polarizer and the two-coil spin flipper. The intensity distribution of the neutrons focused by the MNL at the detector position was measured by using a high-resolution photomultiplier-based scintillation detector. In this paper, the neutron focusing property of the focusing setup is investigated, and the performance of the FSANS instrument is discussed.
Koizumi, Satoshi; Iwase, Hiroki; Suzuki, Junichi; Oku, Takayuki; Motokawa, Ryuhei; Sasao, Hajime*; Tanaka, Hirokazu; Yamaguchi, Daisuke; Shimizu, Hirohiko; Hashimoto, Takeji
Physica B; Condensed Matter, 385-386(2), p.1000 - 1006, 2006/11
Times Cited Count：41 Percentile：81.06(Physics, Condensed Matter)no abstracts in English
Koizumi, Satoshi; Iwase, Hiroki; Tanaka, Hirokazu; Hashimoto, Takeji; Suzuki, Junichi; Oku, Takayuki; Sasao, Hajime*; Shimizu, Hirohiko
Hamon, 14(4), p.266 - 274, 2004/10
no abstracts in English
Seki, Masahiro; Hishinuma, Akimichi; Kurihara, Kenichi; Akiba, Masato; Abe, Tetsuya; Ishitsuka, Etsuo; Imai, Tsuyoshi; Enoeda, Mikio; Ohira, Shigeru; Okumura, Yoshikazu; et al.
Kaku Yugoro Kogaku Gairon; Mirai Enerugi Eno Chosen, 246 Pages, 2001/09
no abstracts in English
Masui, Tomomi; Shikinaka, Kazuhiro*; Kwon, H.*; Koizumi, Satoshi; Hashimoto, Takeji; Iwase, Hiroki; Kakugo, Akira*; Gong, J.*
no journal, ,
no abstracts in English
