Omasa, Yoshinori*; Takagi, Shigeyuki*; Toshima, Kento*; Yokoyama, Kaito*; Endo, Wataru*; Orimo, Shinichi*; Saito, Hiroyuki*; Yamada, Takeshi*; Kawakita, Yukinobu; Ikeda, Kazutaka*; et al.
Physical Review Research (Internet), 4(3), p.033215_1 - 033215_9, 2022/09
Tripathi, R.*; Adroja, D. T.*; Ritter, C.*; Sharma, S.*; Yang, C.*; Hillier, A. D.*; Koza, M. M.*; Demmel, F.*; Sundaresan, A.*; Langridge, S.*; et al.
Physical Review B, 106(6), p.064436_1 - 064436_17, 2022/08
Arai, Yosuke*; Kuroda, Kenta*; Nomoto, Takuya*; Tin, Z. H.*; Sakuragi, Shunsuke*; Bareille, C.*; Akebi, Shuntaro*; Kurokawa, Kifu*; Kinoshita, Yuto*; Zhang, W.-L.*; et al.
Nature Materials, 21(4), p.410 - 415, 2022/04
Hashimoto, Shunsuke*; Nakajima, Kenji; Kikuchi, Tatsuya*; Kamazawa, Kazuya*; Shibata, Kaoru; Yamada, Takeshi*
Journal of Molecular Liquids, 342, p.117580_1 - 117580_8, 2021/11
Quasi-elastic neutron scattering (QENS) and pulsed-field-gradient nuclear magnetic resonance (PFGNMR) analyses of a nanofluid composed of silicon dioxide (SiO) nanoparticles and a base fluid of ethylene glycol aqueous solution were performed. The aim was to elucidate the mechanism increase in the thermal conductivity of the nanofluid above its theoretical value. The obtained experimental results indicate that SiO particles may decrease the self-diffusion coefficient of the liquid molecules in the ethylene glycol aqueous solution because of their highly restricted motion around these nanoparticles. At a constant temperature, the thermal conductivity increases as the self-diffusion coefficient of the liquid molecules decreases in the SiO nanofluids.
Tominaga, Taiki*; Kobayashi, Makoto*; Yamada, Takeshi*; Matsuura, Masato*; Kawakita, Yukinobu; Kasai, Satoshi*
JPS Conference Proceedings (Internet), 33, p.011095_1 - 011095_5, 2021/03
A vertical movement type of sample changer for the neutron spectrometer BL02, J-PARC MLF was developed for our top-loading type cryostat. The sample changer, termed as "PEACE", can control reproducibility of the irradiated position using guides made of polyether ether ketone. The variation between the background scattering profiles of three sample positions was found to be less than plus minus 1.6%. This result is reasonable, considering the deviation of sample position of less than plus minus 0.3 mm from the vertical axis.
Tominaga, Taiki*; Kawakita, Yukinobu; Nakagawa, Hiroshi; Yamada, Takeshi*; Shibata, Kaoru
JPS Conference Proceedings (Internet), 33, p.011086_1 - 011086_5, 2021/03
We developed a quartz double cylindrical sample cell optimized for a backscattering neutron spectrometer, especially for BL02 (DNA), MLF in J-PARC. A quartz glass tube, with one end closed, is shaved to obtain a wall thickness of 0.55 mm. The inner tube is properly centered using a protrusion into the outer tube such that the interstice between the outer and inner tubes keeps constant. This quartz cell can be used for samples that should not be in contact with the aluminum surface. We verified cell's background effect between the quartz cell and Al cell by QENS measurements using DO buffer. The elastic intensity profiles of the buffer in a low Q region were identical between both quartz cell and Al cell (A1070). In a high Q region, however, the profiles were different caused by the first sharp diffraction peak of quartz glass. For this region the data should be analyzed by consideration of absorption correction and diffraction in individual thickness of quartz cell.
Gonzalz, M. A.*; Borodin, O.*; Kofu, Maiko; Shibata, Kaoru; Yamada, Takeshi*; Yamamuro, Osamu*; Xu, K.*; Price, D. L.*; Saboungi, M.-L.*
Journal of Physical Chemistry Letters (Internet), 11(17), p.7279 - 7284, 2020/09
JAEA-Review 2019-046, 36 Pages, 2020/03
Toward the revision of JENDL-4.0, we conducted a literature survey on how to compute the cross section of thermal neutrons scattered by a liquid. This report summarizes the computational methods for evaluating thermal neutron cross sections with molecular dynamics simulations. The cross section can be expressed with a function called as scattering law. For light and heavy water, the scattering law data instead of the cross sections have been provided in nuclear databases. In this report we review the formulations of the scattering laws. The scattering laws can be derived from both the intermediate scattering function and the space-time correlation function. Features of the derived scattering laws are briefly explained. It is shown that the scattering law data can be evaluated using a molecular dynamics simulation of the liquid that is the target of thermal neutrons.
Fujiwara, Satoru*; Matsuo, Tatsuhito*; Sugimoto, Yasunobu*; Shibata, Kaoru
Journal of Physical Chemistry Letters (Internet), 10(23), p.7505 - 7509, 2019/12
Characterization of the dynamics of disordered polypeptide chains is required to elucidate the behavior of intrinsically disordered proteins and proteins under non-native states related to the folding process. Here we develop a method using quasielastic neutron scattering, combined with small-angle X-ray scattering and dynamic light scattering, to evaluate segmental motions of proteins as well as diffusion of the entire molecules and local side-chain motions. We apply this method to RNase A under the unfolded and molten-globule (MG) states. The diffusion coefficients arising from the segmental motions are evaluated and found to be different between the unfolded and MG states. The values obtained here are consistent with those obtained using the fluorescence-based techniques. These results demonstrate not only feasibility of this method but also usefulness to characterize the behavior of proteins under various disordered states.
Fujiwara, Satoru*; Kono, Fumiaki*; Matsuo, Tatsuhito*; Sugimoto, Yasunobu*; Matsumoto, Tomoharu*; Narita, Tetsuhiro*; Shibata, Kaoru
Journal of Molecular Biology, 431(17), p.3229 - 3245, 2019/08
-synuclein (Syn) is an intrinsically disordered protein (IDP) with unknown function. Syn is known to form amyloid fibrils, which are implicated with the pathogenesis of Parkinson's disease and other synucleinopathies. Elucidating the mechanism of fibril formation of Syn is therefore important for understanding the mechanism of the pathogenesis of these diseases. Here, using the quasielastic neutron scattering (QENS) and small-angle X-ray scattering (SAXS) techniques, we investigated the dynamic and structural properties of Syn. These results imply that fibril formation of Syn requires not only the enhanced local motions but also the segmental motions such that the proper inter-molecular interactions are possible.
Journal of the Physical Society of Japan, 88(8), p.081008_1 - 081008_11, 2019/08
Teshigawara, Makoto; Tsuchikawa, Yusuke*; Ichikawa, Go*; Takata, Shinichi; Mishima, Kenji*; Harada, Masahide; Oi, Motoki; Kawamura, Yukihiko*; Kai, Tetsuya; Kawamura, Seiko; et al.
Nuclear Instruments and Methods in Physics Research A, 929, p.113 - 120, 2019/06
A nano-diamond is an attractive neutron reflection material below cold neutron energy. The total neutron cross section of a nano-diamond was derived from a neutron transmission measurement over the neutron energy range of 0.2 meV to 100 meV because total neutron cross section data were not available. The total cross section of a nano-diamond with particle size of approximately 5 nm increased with a decrease in neutron energy to 0.2 meV. It was approximately two orders of magnitude larger than that of graphite at 0.2 meV. The contribution of inelastic scattering to the total cross section was to be shown negligible small at neutron energies of 1.2, 1.5, 1.9, 2.6, and 5.9 meV in the inelastic neutron scattering measurement. Moreover, small-angle neutron scattering measurements of the nano-diamond showed a large scattering cross section in the forward direction for low neutron energies.
Kawamura, Seiko; Takahashi, Ryuta*; Ishikado, Motoyuki*; Yamauchi, Yasuhiro*; Nakamura, Masatoshi*; Ouchi, Keiichi*; Kira, Hiroshi*; Kambara, Wataru*; Aoyama, Kazuhiro*; Sakaguchi, Yoshifumi*; et al.
Journal of Neutron Research, 21(1-2), p.17 - 22, 2019/05
The Cryogenics and Magnets group in the Sample Environment team is responsible for operation of cryostats and magnets for user's experiments at the MLF in J-PARC. We have introduced a top-loading He cryostat, a bottom-loading He cryostat, a dilution refrigerator insert and a superconducting magnet. The frequency of use of them dramatically becomes higher in these two years, as the beam power and the number of proposal increase. To respond such situation, we have made efforts to enhance performance of these equipment as follows. The He cryostat originally involves an operation software for automatic initial cooling down to the base temperature and automatic re-charge of He. Recently we made an additional program for automatic temperature control with only the sorb heater. Last year, a new outer vacuum chamber of the magnet with an oscillating radial collimator (ORC) was fabricated. The data quality was drastically improved by introducing this ORC so that the magnet can be used even for the inelastic neutron scattering experiments.
Okuchi, Takuo*; Tomioka, Naotaka*; Purevjav, N.*; Shibata, Kaoru
Journal of Applied Crystallography, 51, p.1564 - 1570, 2018/12
It is demonstrated that quasielastic neutron scattering (QENS) is a novel and effective method to analyse atomic scale hydrogen transport processes occurring within a mineral crystal lattice. The method was previously characterized as sensitive for analysing the transport frequency and distance of highly diffusive hydrogen atoms or water molecules in condensed matter. Here are shown the results of its application to analyse the transport of much slower hydrogen atoms which are bonded into a crystal lattice as hydroxyls. Two types of hydrogen transport process were observed in brucite, Mg(OH) : a jump within a single two-dimensional layer of the hydrogen lattice and a jump into the next nearest layer of it. These transport processes observed within the prototypical structure of brucite have direct implications for hydrogen transport phenomena occurring within various types of oxides and minerals having layered structures.
Metoki, Naoto; Haga, Yoshinori; Yamamoto, Etsuji; Matsuda, Masaaki*
Journal of the Physical Society of Japan, 87(11), p.114712_1 - 114712_9, 2018/11
The localized 5 states with 5 () configuration of U ion have been revealed in UPdAl. We found that the low-lying states are the same as PrPdAl flat orbitals with large are stabilized by a two-dimensional CEF potential in the unique crystal structure. The present study involves the valence crossover from tetravalent to trivalent in a series of AnPdAl, demonstrated by lattice and/or transport anomaly as well as many body effects in the vicinity of the boundary. The valence instability plays important role for the unusual heavy fermion superconductivity in NpPdAl.
Yoshida, Koji*; Inoue, Takuya*; Torigoe, Motokatsu*; Yamada, Takeshi*; Shibata, Kaoru; Yamaguchi, Toshio*
Journal of Chemical Physics, 149(12), p.124502_1 - 124502_10, 2018/09
Differential scanning calorimetry, X-ray diffraction, and quasi-elastic neutron scattering (QENS) measurements of aqueous glycine solutions confined in mesoporous silica (MCM-41) were performed at different glycine concentrations, pH, and loading ratio (= mass of glycine solution / mass of dry MCM-41) in the temperature range from 305 to 180 K to discuss the confinement effect on the thermal behavior, the structure, and the dynamic properties of the solutions.
Metoki, Naoto; Yamauchi, Hiroki; Suzuki, Hiroyuki*; Kitazawa, Hideaki*; Hagihara, Masato*; Masuda, Takatsugu*; Aczel, A. A.*; Chi, S.*; Hong, T.*; Matsuda, Masaaki*; et al.
Journal of the Physical Society of Japan, 87(9), p.094704_1 - 094704_8, 2018/09
The -electron states of PrPdAl were revealed by neutron inelastic scattering. The flat -orbitals with large become stable under the two-dimensional CEF potential of unique crystal structure, which is the origin of the Ising anisotropy. A systematic understanding is possible in RPdAl based on this CEF potential. Especially the -type anisotropy in NpPdAl can be qualitatively understood with the positive Stevens factors. It mean that the local property is important for the physical properties of RPdAl including the heavy fermion superconductivity in NpPdAl.
Abe, Hiroshi*; Yamada, Takeshi*; Shibata, Kaoru
Journal of Molecular Liquids, 264, p.54 - 57, 2018/08
Metoki, Naoto; Yamauchi, Hiroki; Suzuki, Hiroyuki*; Kitazawa, Hideaki*; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro
Journal of the Physical Society of Japan, 87(8), p.084708_1 - 084708_7, 2018/08
Inelastic neutron scattering experiments were carried out in order to study the -electron states of NdPdAlThe CEF levels at 0K, 35.4K, 88.3K, 101.5K, and 198.8K were clarified from the excitation spectra. The ground state contains the orbital with as a main component due to a large negative BK, which is the origin of the strong uniaxial anisotropy. The estimated magnetic moment, the calculated susceptibility, magnetization curve, and specific heat are in good agreement with the experimental data. The existence of a common charge distribution with CePdAl and PrPdAl. Indicates that a localized character is important even in actinide-based iso-structural compounds as actually observed in UPdAl and also NpPdAl, in which the valence crossover plays important role for the heavy fermion superconductivity.
Fukushima, Yoshiaki*; Yamada, Takeshi*; Tamura, Kenji*; Shibata, Kaoru
Applied Clay Science, 155, p.15 - 19, 2018/04
Dynamics of a fluoromica (ME100) cation exchanged for dioctadecyl dimethyl ammonium ion (DODA)/ polypropylene composite was analyzed by quasi elastic neutron scattering (QENS), besides XRD and DSC. The QENS spectra for the DODA-ME100 at low Q=2.75 nm were not changed even at temperature higher than 445 K, the melting point of DODA. The results suggested the long range ( 2 nm) molecular motions in interlayer space are restricted due to the rigid silicate layers and the strong electrostatic interaction between DODA and the ME100. Elastic intensity scan results suggested that a little amount of motion of the polymer chains in the composite was also restricted in the molten state at 445 K. The QENS is expected to be one of the useful tools for studying the composite materials.