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Kawai, Kiyoshi*; Sogabe, Tomochika*; Nakagawa, Hiroshi; Yamada, Takeshi*; Koseki, Shigenobu*
Journal of Food Engineering, 375, p.112066_1 - 112066_9, 2024/08
Times Cited Count：1 Percentile：37.31(Engineering, Chemical)The purpose of this study was to clarify effect of glycerol and glucose on the mechanical glass transition and dynamical transition of freeze-dried bacteria at various water activity (aw)-conditions. From the water sorption isotherm, it was noted that the water content at each aw and monolayer water content were higher in the order of glycerol, glucose, non-added samples. Effect of temperature on the mean square displacement (MSD) of atoms in the samples was investigated by incoherent elastic neutron scattering. The MSD increased gradually with an increase in temperature depending on the aw and added solute. From the linear fitting, three dynamical transition temperatures (low-, middle- and high-Tds) were determined. The Couchman-Karasz model suggested that the added solute and bacteria were not completely miscible.
Sogabe, Tomochika*; Nakagawa, Hiroshi; Yamada, Takeshi*; Koseki, Shigenobu*; Kawai, Kiyoshi*
Biophysical Journal, 121(20), p.3874 - 3882, 2022/10
Times Cited Count：3 Percentile：29.07(Biophysics)The purpose of this study was to clarify the glass transition behavior of bacteria (
) as a function of water activity (
). Mechanical relaxation was investigated at 298 K, and the mechanical 
( at which mechanical glass transition occurs at 298 K) was determined to be 0.667. Temperature-dependency of mean square displacement was investigated by inelastic neutron scattering. From the linear fitting, two dynamical transition temperatures (low and high-
) were determined. There was a minor effect of on the low- except for the anhydrous sample. The high- largely increased with the decrease in . The dynamical determined by high- (0.688) was slightly higher than the mechanical because of the difference in the measurement time-scale. The high- was converted to the glass transition temperature (
), and anhydrous was estimated to be 411 K. Bacterial inactive-active transition was discussed according to the glass transition behavior.
Kawai, Chika*; Idomura, Yasuhiro; Ogawa, Yuichi*; Yamada, Hiroshi*
Physics of Plasmas, 27(8), p.082302_1 - 082302_11, 2020/08
Times Cited Count：2 Percentile：10.47(Physics, Fluids & Plasmas)Self-organization in the toroidal electron temperature gradient driven (ETG) turbulence is investigated based on a global gyrokinetic model in a weak magnetic shear configuration. Because of global profile effects, toroidal ETG modes with higher toroidal mode number n are excited at the outer magnetic surfaces, leading to strong linear wave dispersion. The resulting anisotropic wave turbulence boundary and the inverse energy cascade generate the self-organization of zonal flows, which is the unique mechanism in the global gyrokinetic model. The self-organization is confirmed both in the decaying turbulence initialized by random noises and in the toroidal ETG turbulence. It is also shown that the self-organization process generates zonal flows and isotropic eddies depending on a criterion parameter, which is determined by the ion to electron temperature ratio and the turbulence intensity.
Kawai, Chika*; Idomura, Yasuhiro; Maeyama, Shinya*; Ogawa, Yuichi*
Physics of Plasmas, 24(4), p.042303_1 - 042303_13, 2017/04
Times Cited Count：2 Percentile：9.25(Physics, Fluids & Plasmas)Self-organization in the slab electron temperature gradient driven (ETG) turbulence is investigated based on gyrokinetic simulations and the Hasegawa-Mima (HM) equation. The scale and the anisotropy of self-organized turbulent structures vary depending on the Rhines scale and the characteristic scale given by the adiabatic response term in the HM equation. The former is determined by competition between the linear wave dispersion and the nonlinear turbulent cascade, while the latter is given as the scale, at which the turbulent cascade is impeded. These scales are controlled by plasma parameters such as the density and temperature gradient, and the temperature ratio of ion to electron. It is found that depending on the plasma parameters, the ETG turbulence shows either isotropic turbulence or zonal flows, which give significantly different transport levels. Although the modulational instability excites zonal modes regardless of the plasma parameters, the final turbulent structure is determined by the self-organization process.
Takayama, Yusuke*; Ikuta, Yuki*; Iizuka, Atsushi*; Kawai, Katsuyuki*; Taki, Tomihiro; Sakao, Ryota; Ichikawa, Yasuaki*
Unsaturated Soils; Research & Applications, p.659 - 665, 2014/06
In this paper, a multiple unsaturated soil barrier consisting of gravel, sand and bentonite-mixed soil layers is considered as a hardly permeable covering to prevent rainwater from infiltrating into waste deposits. Not only the quite low permeability of bentonite-mixed soil layer but also a function of capillary barrier between granular layers having different water-retention capabilities is expected to prevent water infiltration. A series of numerical simulation is carried out to evaluate performance of the multiple soil barrier using saturated/unsaturated soil/water coupled FE computation technique. The multiple unsaturated soil barrier system considered here is 10m long and 1.5 m thick consisting of sandy soil surface, sand filter, gravel layer, sand filter and bentonite-mixed clayey layer. And the soil barrier system is assumed to be placed as a covering with a 5% inclination on the waste deposit. The performance of the multiple soil barrier system is shown as a management chart to maintain impermeable ability associated with possible rainfall intensity. Particularly, in this paper, actual rainfall record in Okayama area is employed to determine the rainfall intensity which is imposed as a boundary condition in the computation. According to the simulation results, it is found that the capillary barrier is a key issue in evaluating the long term performance of the barrier system. And, it is confirmed that the barrier system considered in this paper can work well against the maximum intensity of the rainfall in the past record.
M
asson, M.-A.*; Muranaka, Hiroshi*; Matsuda, Tatsuma; Kawai, Tomoya*; Haga, Yoshinori; Knebel, G.*; Aoki, Dai*; Lapertot, G.*; Honda, Fuminori*; Settai, Rikio*; et al.
Physica C, 470(Suppl.1), p.S536 - S538, 2010/12
Times Cited Count：5 Percentile：25.14(Physics, Applied) realized at the quantum critical pointSettai, Rikio*; Kawai, Tomoya*; Miyauchi, Yuichiro*; Okuda, Yusuke*; Onuki, Yoshichika; Takeuchi, Tetsuya*; Tateiwa, Naoyuki; Matsuda, Tatsuma; Haga, Yoshinori; Harima, Hisatomo*
Kotai Butsuri, 43(8), p.459 - 474, 2008/08
The magnetic transition temperature of an antiferromagnet CeIrSi decreases with increasing hydrostatic pressure, and finally superconductivity appears. An exotic superconducting symmetry is expected because of the absence of the inversion center in the crystal structure. One of the prominent features is the anomalously large upper critical field observed around the quantum critical point.
(T:transition metal and X:Si and Ge) with non-centrosymmetric crystal structureKawai, Tomoya*; Muranaka, Hiroshi*; Masson, M.-A.*; Shimoda, Tetsuya*; Doi, Yusuke*; Matsuda, Tatsuma; Haga, Yoshinori; Knebel, G.*; Lapertot, G.*; Aoki, Dai*; et al.
Journal of the Physical Society of Japan, 77(6), p.064716_1 - 064716_9, 2008/06
Times Cited Count：69 Percentile：89.14(Physics, Multidisciplinary)Physical properties of cerium compounds CeTX were studied on single crystals. Electrical resistivity, magnetization as well as their pressure dependence revealed that the antiferromagnetism of CeCoGe is destroyed under hydrostatic pressure above 5.4 GPa and the superconductivity appears above this pressure.
(T:transition metal) and PrCoGe with the non-centrosymmetric crystal structureKawai, Tomoya*; Muranaka, Hiroshi*; Endo, Toyoaki*; Nguyen, D.; Doi, Yusuke*; Ikeda, Shugo*; Matsuda, Tatsuma; Haga, Yoshinori; Harima, Hisatomo*; Settai, Rikio*; et al.
Journal of the Physical Society of Japan, 77(6), p.064717_1 - 064717_15, 2008/06
Times Cited Count：50 Percentile：84.95(Physics, Multidisciplinary)Fermi surfaces of the non-centrosymmetric LaTGe and PrCoGe have been studied in detail using the de Haas-van Alphen effect. Splitting of the conduction bands due to the spin-orbit interaction was clearly observed. These results are important in understanding the exotic superconductivity realized in non-centrosymmetric structure.
without inversion symmetry in the crystal structureKawai, Tomoya*; Okuda, Yusuke*; Shishido, Hiroaki*; Thamizhavel, A.*; Matsuda, Tatsuma; Haga, Yoshinori; Nakashima, Miho*; Takeuchi, Tetsuya*; Hedo, Masato*; Uwatoko, Yoshiya*; et al.
Journal of the Physical Society of Japan, 76(1), p.014710_1 - 014710_6, 2007/01
Times Cited Count：23 Percentile：71.27(Physics, Multidisciplinary)We succeeded in growing a single crystal of CePtSi by the Sn-flux method. CePtSi is found to be an antiferromagnet with two transitions at 4.8 and 2.4 K. Magnetic easy direction was [100] direction with an ordered moment of 1.15 
/Ce. The anisotropy is similar to that of CeIrSi in which the pressure-induced superconductivity was observed.
Nakashima, Hiroshi; Takada, Hiroshi; Kasugai, Yoshimi; Meigo, Shinichiro; Maekawa, Fujio; Kai, Tetsuya; Konno, Chikara; Ikeda, Yujiro; Oyama, Yukio; Watanabe, Noboru; et al.
Proceedings of 6th Meeting of the Task Force on Shielding Aspects of Accelerators, Targets and Irradiation Facilities (SATIF-6), (OECD/NEA No.3828), p.27 - 36, 2004/00
no abstracts in English
Nakashima, Hiroshi; Takada, Hiroshi; Kasugai, Yoshimi; Meigo, Shinichiro; Maekawa, Fujio; Kai, Tetsuya; Konno, Chikara; Ikeda, Yujiro; Oyama, Yukio; Watanabe, Noboru; et al.
Journal of Nuclear Science and Technology, 39(Suppl.2), p.1155 - 1160, 2002/08
no abstracts in English
Sugimoto, Masayoshi; Kinsho, Michikazu; Kawai, Masayoshi*; M.Chernogubovsky*
Proc. of 11th Symp. on Accelerator Sci. and Technol., p.127 - 129, 1997/00
no abstracts in English
Sugimoto, Masayoshi; Kinsho, Michikazu; M.Chernogubovsky*; Kawai, Masayoshi*;
Proc. of 22nd Linear Accelerator Meeting in Japan, p.101 - 103, 1997/00
no abstracts in English
Kawai, Chika; Idomura, Yasuhiro; Maeyama, Shinya*; Ogawa, Yuichi*
no journal, ,
To investigate relations between self-organization and flow structure formation in magnetized plasmas, energy spectrum structures of electron turbulence are estimated by gyrokinetic simulations. It is found that the existence of zonal flow formation is affected by the plasma density and the temperature ratio between ions and electrons, which change wave dispersion induced by diamagnetic rotation. Depending on saturation amplitudes of turbulence, zonal flow formation processes are varied from an inverse energy cascade due to self-organization to a modulational instability due to direct mode coupling. These results suggest that structures of electron turbulence are significantly changed by macroscopic plasma parameters.
Idomura, Yasuhiro; Matsuoka, Seikichi; Ina, Takuya; Garbet, X.*; Brunner, S.*; Villard, L.*; Kawai, Chika*
no journal, ,
This talk reviews outcomes from GT5DISO projects, which was conducted for FY2014-2016. In this project, isotope effects on turbulent transport have been studied using the gyrokinetic toroidal five dimensional full-f Eulerian code GT5D. In FY2014, it was shown that the ion temperature gradient driven (ITG) turbulence with adiabatic electrons does not show isotope effects, and the trapped electron mode (TEM) driven by kinetic trapped electrons is essential for this issue. In FY2015, a new hybrid kinetic electron model was developed in GT5D, and its verification tests for ITG-TEM turbulence simulations were conducted. In FY2016, the kinetic electron model was validated against electron heating modulation experiments, in which the TEM turbulence plays key roles in particle and momentum transport. Finally, we performed isotope scan of ITG-TEM turbulence simulations, which tend to indicate difference of confinement between hydrogen and deuterium plasmas.
Kawai, Chika; Maeyama, Shinya; Idomura, Yasuhiro; Ogawa, Yuichi*
no journal, ,
Self organization through inverse energy cascade in quasi two dimensional turbulence spectra is considered as a mechanism of the formation of zonal flow structure in magnetized plasma. However, relation between turbulence energy spectra and formation of zonal flow structure has not been clarified in first-principles based plasma turbulence simulations. In this study, we examine relations between turbulent energy spectra and structure formations due to self-organization, which are derived from a fluid description of plasma turbulence, the Hasegawa-Mima equation, using gyrokinetic Vlasov simulations of electron turbulence.
Kawai, Chika; Idomura, Yasuhiro; Maeyama, Shinya; Ogawa, Yuichi*
no journal, ,
In estimating confinement properties of fusion plasmas, it is a critical issue to understand structures of turbulent spectra, leading to turbulent transport. In this study, self-organization processes, which produce zonal flows from electron turbulence, are analyzed in detail via a highly accurate gyrokinetic Eulerian code, and structures of turbulent spectra leading to zonal flow generation are clarified.
Kawai, Chika; Maeyama, Shinya; Idomura, Yasuhiro; Ogawa, Yuichi*
no journal, ,
Self-organization through inverse cascades of energy in a turbulent spectrum is considered as one of the paths to formation of zonal flow structures in magnetized plasma. Despite the theoretical suggestion, relations between the turbulence energy spectrum and the formation of zonal flow structures have not been rigorously investigated in terms of numerical simulation studies based on a first-principle model. In this study, spectrum structures of electron scale plasma turbulence are obtained from high-resolution Vlasov simulations. The long wave length region of the spectrum is investigated in relation with self-organization.
Ikuta, Yuki*; Takayama, Yusuke*; Tsurumi, Shuhei*; Ichikawa, Yasuaki*; Iizuka, Atsushi*; Kawai, Katsuyuki*; Taki, Tomihiro; Sakao, Ryota
no journal, ,
As a part of remediation of closed uranium mine, "Yotsugi Mill Tailings Pond" has been remediated in Ningyo-toge Environmental Engineering Center, Japan Atomic Energy Agency. The aim of remediation is to take measures to reduce the load of water treatment and the radon exposure to humans in future, and to prevent the occurrence of relevant environmental contamination. So far, the upstream of the Pond has been covered by the multi-layered capping in which layers are set to use gravel, sand and decomposed granite soil to drain penetrated rainwater to the neighboring river. This capping system needs to be monitored on a long-term basis and to be evaluated to work as expected in advance, therefore seepage analysis and settlement analysis has carried out. As a result, Settlement of analysis was well accorded with measured value and marked change of saturation accompanied by rain was not observed in the seepage analysis.
