Contrast dependence of scattering profiles for poly(ethylene glycol) in water; Investigation by small-angle neutron scattering with He spin filter and small-angle X-ray scattering

Ryoki, Akiyuki*; Watanabe, Fumi*; Okudaira, Takuya*; Takahashi, Shingo*; Oku, Takayuki; Hiroi, Kosuke; Motokawa, Ryuhei; Nakamura, Yo*

Journal of Chemical Physics, 160(11), p.114907_1 - 114907_9, 2024/03

https://doi.org/10.1063/5.0192680

Water fraction dependence of the aggregation behavior of hydrophobic fluorescent solutes in water-tetrahydrofuran

Tsuji, Hayato*; Nakahata, Masaki*; Hishida, Mafumi*; Seto, Hideki*; Motokawa, Ryuhei; Inoue, Takeru*; Egawa, Yasunobu*

Journal of Physical Chemistry Letters (Internet), 14(49), p.11235 - 11241, 2023/12

https://doi.org/10.1021/acs.jpclett.3c02882

Heterogeneous aggregation of humic acids studied by small-angle neutron and X-ray scattering

Saito, Takumi*; Motokawa, Ryuhei; Okubo, Takahiro*; Miura, Daisuke*; Kumada, Takayuki

Environmental Science & Technology, 57(26), p.9802 - 9810, 2023/07

https://doi.org/10.1021/acs.est.3c02028

Microscopic structural changes during the freeze cross-linking reaction in carboxymethyl cellulose nanofiber hydrogels

Miura, Daisuke*; Sekine, Yurina; Nankawa, Takuya; Sugita, Tsuyoshi; Oba, Yojiro; Hiroi, Kosuke; Ozawa, Tatsuhiko

Carbohydrate Polymer Technologies and Applications (Internet), 4, p.100251_1 - 100251_9, 2022/12

https://doi.org/10.1016/j.carpta.2022.100251

The reaction mechanism of carboxymethyl cellulose nanofiber (CMCF) hydrogel formed by freeze-crosslinking was investigated. We succeeded in observing the hierarchical structural changes during the freeze-crosslinking reaction. Freeze-crosslinked CMCF hydrogels exhibited a characteristic hierarchical alignment structure from the angstrom to micrometer scale that differed from normal cross-linked CMCF hydrogels produced by a conventional method without freezing. It was shown that the characteristic hierarchical structure contributes the excellent mechanical properties of freeze-crosslinked CMCF hydrogels.

Polarization analysis for small-angle neutron scattering with a 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

https://doi.org/10.1107/S1600576721001643

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.

X-ray and neutron study on the structure of hydrous SiO glass up to 10 GPa

Urakawa, Satoru*; Inoue, Toru*; Hattori, Takanori; Sano, Asami; Kohara, Shinji*; Wakabayashi, Daisuke*; Sato, Tomoko*; Funamori, Nobumasa*; Funakoshi, Kenichi*

Minerals (Internet), 10(1), p.84_1 - 84_13, 2020/01

https://doi.org/10.3390/min10010084

The structure of hydrous amorphous SiO is fundamental to investigate the effects of water on the physicochemical properties of oxide glasses and magma. The hydrous SiO glass with 13 wt.% DO was synthesized under high-pressure and high-temperature conditions and its structure was investigated by small angle X-ray scattering, X-ray diffraction, and neutron diffraction experiments at pressures of up to 10 GPa and room temperature. This hydrous glass is separated into a SiO rich major phase and a DO rich minor phase. Medium-range order of the hydrous glass shrinks compared to the anhydrous SiO glass due to disruption of SiO linkage by formation of Si-OD deuterioxyl, while the pressure response is similar. Most of DO molecules are in the small domains and hardly penetrate into SiO major phase.

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

https://doi.org/10.1021/acs.langmuir.9b01132

Phase-transition kinetics of magnetic skyrmions investigated by stroboscopic small-angle neutron scattering

Nakajima, Taro*; Inamura, Yasuhiro; Ito, Takayoshi*; Oishi, Kazuki*; Oike, Hiroshi*; Kagawa, Fumitaka*; Kikkawa, Akiko*; Taguchi, Yasujiro*; Kakurai, Kazuhisa*; Tokura, Yoshinori*; et al.

Physical Review B, 98(1), p.014424_1 - 014424_5, 2018/07

https://doi.org/10.1103/PhysRevB.98.014424

We investigated the phase-transition kinetics of magnetic skyrmion lattice (SkL) in MnSi by means of stroboscopic small-angle neutron scattering (SANS). Temporal evolutions of SANS patterns were measured with time resolution of 13 ms while sweeping temperature as fast as 50 Ks. It turned out that the paramagnetic-to-SkL transition immediately occurs upon traversing the equilibrium phase boundary on the rapid cooling, whereas the SkL-to-conical transition can be kinetically avoided to realize the low-temperature metastable SkL with a long-range magnetic order. The formation of the metastable SkL was found to be strongly dependent not only on cooling rate, but also on magnetic eld and trajectory in the H-T phase diagram.

Recent research in solvent extraction of platinum group metals

Narita, Hirokazu*; Suzuki, Tomoya*; Motokawa, Ryuhei

Nihon Kinzoku Gakkai-Shi, 81(4), p.157 - 167, 2017/04

https://doi.org/10.2320/jinstmet.JE201604

Nanoscopic structural investigation of physically cross-linked nanogels formed from self-associating polymers

Sekine, Yurina; Endo, Hitoshi*; Iwase, Hiroki*; Takeda, Shigeo*; Mukai, Sadaatsu*; Fukazawa, Hiroshi; Littrell, K. C.*; Sasaki, Yoshihiro*; Akiyoshi, Kazunari*

Journal of Physical Chemistry B, 120(46), p.11996 - 12002, 2016/11

https://doi.org/10.1021/acs.jpcb.6b06795

The detailed structure of a nanogel formed by self-association of cholesterol-bearing pullulans (CHP) was determined by contrast variation small-angle neutron scattering. The decomposition of scattering intensities into partial scattering functions of each CHP nanogel component, i.e., pullulan, cholesterol, and the cross-term between the pullulan and the cholesterol allows us to investigate the internal structure of the nanogel. The effective spherical radius of the skeleton formed by pullulan chains was found to be about 8.1 nm. In the CHP nanogel, there are about 19 cross-linking points where a cross-linking point is formed by aggregation of trimer cholesterol molecules with the spatially inhomogeneous distribution of the mass fractal dimension of 2.6. The average radius of the partial chains can also be determined to be 1.7 nm. As the result, the complex structure of the nanogels is coherently revealed at the nanoscopical level.