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Journal Articles

Hierarchical aggregation in a complex fluid; The Role of isomeric interconversion

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

 Times Cited Count:0 Percentile:0(Chemistry, Physical)

Journal Articles

Deuterated malonamide synthesis for fundamental research on solvent extraction systems

Micheau, C.; Ueda, Yuki; Akutsu, Kazuhiro*; Bourgeois, D.*; Motokawa, Ryuhei

Solvent Extraction and Ion Exchange, 20 Pages, 2023/00

 Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)

Journal Articles

Structural Approach to Understanding the Formation of Amorphous Metal Hydroxides

Kobayashi, Taishi*; Fushimi, Tomokazu*; Mizukoshi, Hirofumi*; Motokawa, Ryuhei; Sasaki, Takayuki*

Langmuir, 38(48), p.14656 - 14665, 2022/12

 Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Polymer photonic crystals prepared by triblock copolymerization-induced ${it in situ}$ microphase separation

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

 Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)

Journal Articles

New design of a sample cell for neutron reflectometry in liquid-liquid systems and its application for studying structures at air-liquid and liquid-liquid interfaces

Akutsu-Suyama, Kazuhiro*; Yamada, Norifumi*; Ueda, Yuki; Motokawa, Ryuhei; Narita, Hirokazu*

Applied Sciences (Internet), 12(3), p.1215_1 - 1215_10, 2022/02

 Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)

no abstracts in English

Journal Articles

Nanoscopic structure of borosilicate glass with additives for nuclear waste vitrification

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

 Times Cited Count:1 Percentile:12.48(Materials Science, Ceramics)

Journal Articles

Polarization analysis for small-angle neutron scattering with a $$^{3}$$He spin filter at a pulsed neutron source

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

 Times Cited Count:0 Percentile:0.01(Chemistry, Multidisciplinary)

Neutron polarization analysis (NPA) for small-angle neutron scattering (SANS) experiments using a pulsed neutron source was successfully achieved by applying a $$^{3}$$He spin filter as a spin analyzer for the scattered neutrons. The $$^{3}$$He spin filter covers a sufficient solid angle for performing SANS experiments, and the relaxation time of the $$^{3}$$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.

Journal Articles

Development of spin-contrast-variation neutron powder diffractometry for extracting the structure factor of hydrogen atoms

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


 Times Cited Count:1 Percentile:25.93(Chemistry, Multidisciplinary)

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.

Journal Articles

Introduction to SANS-J and PNO

Kumada, Takayuki; Motokawa, Ryuhei; Nakagawa, Hiroshi; Oba, Yojiro; Sekine, Yurina

Hamon, 31(1), p.5 - 6, 2021/02

no abstracts in English

Journal Articles

Precious metal separations

Narita, Hirokazu*; Kasuya, Ryo*; Suzuki, Tomoya*; Motokawa, Ryuhei; Tanaka, Mikiya*

Encyclopedia of Inorganic and Bioinorganic Chemistry (Internet), 28 Pages, 2020/12

Journal Articles

Nanostructural characterization of oleyl acid phosphate in poly-$$alpha$$-olefin using small-angle X-ray scattering

Oba, Yojiro; Motokawa, Ryuhei; Hino, Masahiro*; Adachi, Nozomu*; Todaka, Yoshikazu*; Inoue, Rintaro*; Sugiyama, Masaaki*

Chemistry Letters, 49(7), p.823 - 825, 2020/07

 Times Cited Count:0 Percentile:0(Chemistry, Multidisciplinary)

Journal Articles

Anomalous small-angle X-ray scattering (ASAXS) study of irradiation-induced nanostructure change in Fe-ion beam irradiated oxide dispersion-strengthened (ODS) steel

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

 Times Cited Count:1 Percentile:16.13(Materials Science, Multidisciplinary)

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$$^-1$$ and an overlapped shoulder around 0.7 nm$$^-1$$. 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.

Journal Articles

Proton chelating ligands drive improved chemical separations for rhodium

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

 Times Cited Count:10 Percentile:59.01(Chemistry, Inorganic & Nuclear)

Journal Articles

Extraction performance of a fluorous phosphate for Zr(IV) from HNO$$_{3}$$ solution; Comparison with tri-$$n$$-butyl phosphate

Ueda, Yuki; Kikuchi, Kei; Sugita, Tsuyoshi; Motokawa, Ryuhei

Solvent Extraction and Ion Exchange, 37(5), p.347 - 359, 2019/07

 Times Cited Count:8 Percentile:35.69(Chemistry, Multidisciplinary)

We have newly-designed fluorous phosphate(TFP) for the effective Zr(IV) ion extractant as an alternative extractant against the conventional organic phosphate, tri-$$n$$-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$$_{3}$$ contents in the fluorous phase and the stability of the complex, Zr(No$$_{3}$$)$$_{4}$$(TFP)$$_{3}$$.

Journal Articles

Structural approach to understanding the solubility of metal hydroxides

Kobayashi, Taishi*; Nakajima, Shogo*; Motokawa, Ryuhei; Matsumura, Daiju; Saito, Takumi*; Sasaki, Takayuki*

Langmuir, 35(24), p.7995 - 8006, 2019/06

 Times Cited Count:2 Percentile:10.48(Chemistry, Multidisciplinary)

Journal Articles

A Telescoping view of solute architectures in a complex fluid system

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

 Times Cited Count:40 Percentile:87.54(Chemistry, Multidisciplinary)

Journal Articles

A Novel microemulsion phase transition; Toward the elucidation of third-phase formation in spent nuclear fuel reprocessing

Mu, J.*; Motokawa, Ryuhei; Akutsu, Kazuhiro*; Nishitsuji, Shotaro*; Masters, A. J.*

Journal of Physical Chemistry B, 122(4), p.1439 - 1452, 2018/02

 Times Cited Count:33 Percentile:73.99(Chemistry, Physical)

Journal Articles

Local structure analysis of light elements included in simulated radioactive waste glasses by soft X-ray absorption fine structure

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$$^{3}$$ type boron (BO$$_{4}$$) percentage increases and the sp$$^{2}$$ type (BO$$_{3}$$) percentage by increasing the sodium content in glass frits.

Journal Articles

Comparison of the extractabilities of tetrachloro- and tetrabromopalladate(II) ions with a thiodiglycolamide compound

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

 Times Cited Count:9 Percentile:37.55(Chemistry, Analytical)

Journal Articles

A Chemiluminescence sensor with signal amplification based on a self-immolative reaction for the detection of fluoride ion at low concentrations

Hisamatsu, Shugo; Suzuki, Shinichi; Komoto, Shigeo*; Kishikawa, Keiki*; Yamamoto, Yusuke*; Motokawa, Ryuhei; Yaita, Tsuyoshi

Tetrahedron, 73(27-28), p.3993 - 3998, 2017/07

 Times Cited Count:15 Percentile:61.25(Chemistry, Organic)

127 (Records 1-20 displayed on this page)