Massey, D.*; Williams, C. D.*; Mu, J.*; Masters, A. J.*; Motokawa, Ryuhei; Aoyagi, Noboru; Ueda, Yuki; Antonio, M. R.*
Journal of Physical Chemistry B, 127(9), p.2052 - 2065, 2023/03
Micheau, C.; Ueda, Yuki; Akutsu, Kazuhiro*; Bourgeois, D.*; Motokawa, Ryuhei
Solvent Extraction and Ion Exchange, 20 Pages, 2023/00
Kobayashi, Taishi*; Fushimi, Tomokazu*; Mizukoshi, Hirofumi*; Motokawa, Ryuhei; Sasaki, Takayuki*
Langmuir, 38(48), p.14656 - 14665, 2022/12
no abstracts in English
Isozaki, Yuka*; Higashiharaguchi, Seiya*; Kaneko, Naoya*; Yamazaki, Shun*; Taniguchi, Tatsuo*; Karatsu, Takashi*; Ueda, Yuki; Motokawa, Ryuhei
Chemistry Letters, 51(6), p.625 - 628, 2022/06
Akutsu-Suyama, Kazuhiro*; Yamada, Norifumi*; Ueda, Yuki; Motokawa, Ryuhei; Narita, Hirokazu*
Applied Sciences (Internet), 12(3), p.1215_1 - 1215_10, 2022/02
no abstracts in English
Motokawa, Ryuhei; Kaneko, Koji; Oba, Yojiro; Nagai, Takayuki; Okamoto, Yoshihiro; Kobayashi, Taishi*; Kumada, Takayuki; Heller, W. T.*
Journal of Non-Crystalline Solids, 578, p.121352_1 - 121352_7, 2022/02
Okudaira, Takuya; Ueda, Yuki; Hiroi, Kosuke; Motokawa, Ryuhei; Inamura, Yasuhiro; Takata, Shinichi; Oku, Takayuki; Suzuki, Junichi*; Takahashi, Shingo*; Endo, Hitoshi*; et al.
Journal of Applied Crystallography, 54(2), p.548 - 556, 2021/04
Neutron polarization analysis (NPA) for small-angle neutron scattering (SANS) experiments using a pulsed neutron source was successfully achieved by applying a He spin filter as a spin analyzer for the scattered neutrons. The He spin filter covers a sufficient solid angle for performing SANS experiments, and the relaxation time of the He polarization is sufficient for continuous use over a few days, thus reaching the typical duration required for a complete set of SANS experiments. Although accurate evaluation of the incoherent neutron scattering, which is predominantly attributable to hydrogen atoms in samples, is practically difficult using calculations based on the sample elemental composition, the developed NPA approach with consideration of the influence of multiple neutron scattering enabled reliable decomposition of the SANS intensity distribution into the coherent and incoherent scattering components. To date, NPA has not been well established as a standard technique for SANS experiments at pulsed neutron sources. This work is anticipated to greatly contribute to the accurate determination of the coherent neutron scattering component for scatterers in various types of organic sample systems in SANS experiments at J-PARC.
Miura, Daisuke*; Kumada, Takayuki; Sekine, Yurina; Motokawa, Ryuhei; Nakagawa, Hiroshi; Oba, Yojiro; Ohara, Takashi; Takata, Shinichi; Hiroi, Kosuke; Morikawa, Toshiaki*; et al.
Journal of Applied Crystallography, 54(2), p.454 - 460, 2021/04
We developed a spin-contrast-variation neutron powder diffractometry technique that extracts the structure factor of hydrogen atoms, namely, the contribution of hydrogen atoms to a crystal structure factor. Crystals of L-glutamic acid were dispersed in a dpolystyrene matrix containing 4-methacryloyloxy-2,2,6,6,-tetramethyl-1-piperidinyloxy (TEMPO methacrylate) to polarize their proton spins dynamically. The intensities of the diffraction peaks of the sample changed according to the proton polarization, and the structure factor of the hydrogen atoms was extracted from the proton-polarization dependent intensities. This technique is expected to enable analyses of the structures of hydrogen-containing materials that are difficult to determine with conventional powder diffractometry.
Kumada, Takayuki; Motokawa, Ryuhei; Nakagawa, Hiroshi; Oba, Yojiro; Sekine, Yurina
Hamon, 31(1), p.5 - 6, 2021/02
no abstracts in English
Narita, Hirokazu*; Kasuya, Ryo*; Suzuki, Tomoya*; Motokawa, Ryuhei; Tanaka, Mikiya*
Encyclopedia of Inorganic and Bioinorganic Chemistry (Internet), 28 Pages, 2020/12
Oba, Yojiro; Motokawa, Ryuhei; Hino, Masahiro*; Adachi, Nozomu*; Todaka, Yoshikazu*; Inoue, Rintaro*; Sugiyama, Masaaki*
Chemistry Letters, 49(7), p.823 - 825, 2020/07
Kumada, Takayuki; Oba, Yojiro; Motokawa, Ryuhei; Morooka, Satoshi; Tominaga, Aki; Tanida, Hajime; Shobu, Takahisa; Konno, Azusa; Owada, Kenji*; Ono, Naoko*; et al.
Journal of Nuclear Materials, 528, p.151890_1 - 151890_7, 2020/01
We have developed an anomalous small-angle X-ray scattering (ASAXS) diffractometer in SPring-8 to investigate irradiation-induced nanostructural change in ion-beam irradiated stainless steel. A thermally-aged MA956 stainless steel sample displays power-law scattering that follows the Porod law at the magnitude of scattering vector, Q, below 0.5 nm and an overlapped shoulder around 0.7 nm. After the ion-beam irradiation, the intensity of the shoulder remained unchanged, whereas that of the power-law scattering nearly doubled. This result indicates that none of the structural parameters of the Cr-rich nanoprecipitates, such as the number density, size, and interface roughness, were changed by the irradiation.
Narita, Hirokazu*; Nicolson, R. M.*; Motokawa, Ryuhei; Ito, Fumiyuki*; Morisaku, Kazuko*; Goto, Midori*; Tanaka, Mikiya*; Heller, W. T.*; Shiwaku, Hideaki; Yaita, Tsuyoshi; et al.
Inorganic Chemistry, 58(13), p.8720 - 8734, 2019/07
Ueda, Yuki; Kikuchi, Kei; Sugita, Tsuyoshi; Motokawa, Ryuhei
Solvent Extraction and Ion Exchange, 37(5), p.347 - 359, 2019/07
We have newly-designed fluorous phosphate(TFP) for the effective Zr(IV) ion extractant as an alternative extractant against the conventional organic phosphate, tri--butyl phosphate(TBP). Zr(IV) ion extraction system using the TBP has many problems such as the formation of the third phase during liquid-liquid extraction. Here, we develop the fluorous extraction system based on the TFP-perfluorohexane for the Zr(IV) ion extraction to improve the Zr(IV) ion extraction system with an effective extractability and without the third phase formation. Our main findings were that the significant high extraction performance of the TFP for Zr(IV) ion as compared with TBP, and the origins of the high extraction performance of the TFP are related to the water and HNO contents in the fluorous phase and the stability of the complex, Zr(No)(TFP).
Kobayashi, Taishi*; Nakajima, Shogo*; Motokawa, Ryuhei; Matsumura, Daiju; Saito, Takumi*; Sasaki, Takayuki*
Langmuir, 35(24), p.7995 - 8006, 2019/06
Motokawa, Ryuhei; Kobayashi, Toru; Endo, Hitoshi; Mu, J.*; Williams, C. D.*; Masters, A. J.*; Antonio, M. R.*; Heller, W. T.*; Nagao, Michihiro*
ACS Central Science, 5(1), p.85 - 96, 2019/01
Mu, J.*; Motokawa, Ryuhei; Akutsu, Kazuhiro*; Nishitsuji, Shotaro*; Masters, A. J.*
Journal of Physical Chemistry B, 122(4), p.1439 - 1452, 2018/02
Okamoto, Yoshihiro; Nagai, Takayuki; Kaneko, Koji; Motokawa, Ryuhei; Haga, Yoshinori; Yamanaka, Keisuke*; Ota, Toshiaki*
2017-Nendo Seika Kokaigata Riyo Seika Hokokusho (Ritsumeikan Daigaku SR Senta), p.33 - 36, 2018/00
The high-level radioactive waste solution which generated from a spent nuclear fuel reprocessing process are mixed with a borosilicate glass frit in a vitrification process, and a chemical stable glass solidified body is produced. To understand local structure of light elements included in a glass solidified body, we carried out a B K-edge XANES measurement of raw glass frits and simulated radioactive waste glasses. As a result of this estimation of boron local structure in glass samples, it was found that the sp type boron (BO) percentage increases and the sp type (BO) percentage by increasing the sodium content in glass frits.
Narita, Hirokazu*; Maeda, Motoki*; Tokoro, Chiharu*; Suzuki, Tomoya*; Tanaka, Mikiya*; Motokawa, Ryuhei; Shiwaku, Hideaki; Yaita, Tsuyoshi
Analytical Sciences, 33(11), p.1305 - 1309, 2017/11
Hisamatsu, Shugo; Suzuki, Shinichi; Komoto, Shigeo*; Kishikawa, Keiki*; Yamamoto, Yusuke*; Motokawa, Ryuhei; Yaita, Tsuyoshi
Tetrahedron, 73(27-28), p.3993 - 3998, 2017/07