Yoshiki Ishii

Yoshiki Ishii
University of Hyogo · Graduate School of Information Science

Ph.D.

About

39
Publications
3,153
Reads
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350
Citations
Additional affiliations
April 2021 - present
University of Hyogo
Position
  • Lecturer
April 2020 - March 2021
University of Hyogo
Position
  • Lecturer
January 2020 - March 2020
University of Hyogo
Position
  • Professor (Assistant)
Education
April 2014 - March 2017
Niigata University
Field of study
  • Science
April 2012 - March 2014
Niigata University
Field of study
  • Science
April 2008 - March 2012
Niigata University
Field of study
  • Science

Publications

Publications (39)
Article
Full-text available
Bulk copolymerization of alkyl acrylates and cyclodextrin (CD) host monomers produced a single movable cross-network (SC). The CD units acted as movable crosslinking points in the obtained SC elastomer. Introducing movable crosslinks into a poly(ethyl acrylate/butyl acrylate) copolymer resulted in good toughness (Gf) and stress dispersion. Here, to...
Article
The crystal growth of urea was analyzed with all-atom molecular dynamics (MD) simulation for the (001) and (110) faces in contact with aqueous solutions. The local environment of a crystallizing molecule was treated in terms of the numbers of crystalline neighbors and the orientation relative to the crystal surface, and the molecular-level inhomoge...
Article
A key to achieve the accuracy of molecular dynamics (MD) simulation is the set of force fields used to express the atomistic interactions. In particular, the electrostatic interaction remains the main issue for the precise simulation of various ionic soft materials from ionic liquids to their supramolecular compounds. In this study, we test the non...
Article
Full-text available
Elucidating the state of interfacial water, especially the hydrogen-bond configurations, is considered to be key for a better understanding of the functions of polymers that are exhibited in the presence of water. Here, an analysis in this direction is conducted for two water-insoluble biocompatible polymers, poly(2-methoxyethyl acrylate) and cycli...
Article
Full-text available
The nematic-isotropic (NI) phase transition of 4-cyano-4'-pentylbiphenyl (5CB) was simulated using the generalized replica-exchange method (gREM) based on molecular dynamics simulations. The effective temperature is introduced in gREM, allowing the enhanced sampling of configurations in the unstable region, which is intrinsic to the first-order pha...
Article
Molecular size and shape effects are evaluated based on the Stokes-Einstein (SE) relation from the viewpoint of molecular differences between the solute and solvent. To this end, dilute solutions of both an n-alkane in Ar and Ar in an n-alkane were simulated using the molecular dynamics method. The molecular-based SE relation derived for the Lennar...
Preprint
The nematic-isotropic (NI) phase transition of 4-cyano-4'-pentylbiphenyl (5CB) was simulated using the generalized replica-exchange method (gREM) based on molecular dynamics simulations. The effective temperature is introduced in gREM, allowing the enhanced sampling of configurations in the unstable region, which is intrinsic to the first-order pha...
Article
Dicalcium silicate, which is found in steelmaking slag for dephosphorization, exists as the hexagonal α phase at high temperatures. The α‐dicalcium silicate forms a solid solution with tricalcium phosphate in the entire composition range, although the reason for high solubility of phosphorus is unclear in view of the crystal structure. It has previ...
Article
Full-text available
Self-assembled ionic liquid crystals can transport water and ions via the periodic nanochannels, and these materials are promising candidates as water treatment membranes. Molecular insights on the water transport process are, however, less investigated because of computational difficulties of ionic soft matters and the self-assembly. Here we repor...
Article
Ionic liquid (IL)-based electrolytes are a promising material for the development of sodium-ion batteries, and their performance can be quantified by electrical conductivity. In this highly concentrated ionic system, the correlated motions of ion pairs are influential on the ionic transport properties. Herein, all-atom analyses are conducted throug...
Article
Soda–lime–silica is a glassy system of strong industrial interest. In order to characterize its liquid state properties, we performed molecular dynamics simulations employing an aspherical ion model that includes atomic polarization and deformation effects. They allowed us to study the structure and diffusion properties of the system at temperature...
Preprint
Soda-lime-silica is a glassy system of strong industrial interest. In order to characterize its liquid state properties, we performed molecular dynamics simulations employing an aspherical ion model that includes atomic polarization and deformation effects. They allowed to study the structure and diffusion properties of the system at temperatures r...
Article
Ionic liquid (IL) has been considered as a potential electrolyte for developing next-generation sodium-ion batteries. A highly concentrated ionic system such as IL is characterized by the significant influence of intramolecular polarization and intermolecular charge transfer that vary with the combination of cations and anions in the system. In thi...
Article
Formulation of rotational diffusion coefficient and the Stokes-Einstein-Debye (SED) relation is presented for diatomic molecular liquids by molecular dynamics simulation with two-center Lennard-Jones (2CLJ) potentials. Shear viscosity ηsv and rotational diffusion coefficient Dr are expressed as a function of molecular mass and number density N/V, o...
Article
The nonpolarizable force field of ionic liquids is tuned by using the self-consistent scheme of molecular dynamics (MD) simulation and first-principles calculation based on the order-N density functional theory (DFT). The atomic charges are determined by using the whole MD cell for DFT calculation and accounts effectively for the many-body effects...
Article
The development of technologies for nuclear reactors based on molten salts has seen a big resurgence. The success of thermodynamic models for these hinges in part on our ability to predict at the atomistic level the behavior of pure salts and their mixtures under a range of conditions. In this letter, we present high-energy X-ray scattering experim...
Article
Full-text available
The pressure-induced structural transformations in metasilicate MSiO3 glass (M=Mg or Ca) on cold-compression from ambient pressure to 17.5 GPa were investigated by neutron diffraction. The structure of the glass recovered to ambient conditions from a pressure of 8.2 or 17.5 GPa was also investigated by neutron or X-ray diffraction. The experimental...
Article
Through molecular dynamics simulations, we examined the hydrodynamic behavior of the Brownian motion of fullerene particles based on molecular interactions. The solvation free energy and the velocity autocorrelation function (VACF) were calculated by using the Lennard-Jones (LJ) and Weeks-Chandler-Andersen (WCA) potentials for the solute-solvent an...
Article
A spatially resolved version of the density-functional method for solvation thermodynamics is presented by extending the free-energy functional previously established in the one-dimensional, energy representation and formulating a new expression in a mixed four-dimensional representation (three dimensions for position and one dimension for energy)....
Preprint
Full-text available
Through molecular dynamics simulations, we examined hydrodynamic behavior of the Brownian motion of fullerene particles based on molecular interactions. The solvation free energy and the velocity autocorrelation function (VACF) were calculated by using the Lennard-Jones (LJ) and Weeks-Chandler-Andersen (WCA) potentials for the solute-solvent and so...
Article
The Stokes-Einstein (SE) relation is examined for hard-sphere (HS) and Weeks-Chandler-Andersen (WCA) fluids by the molecular dynamics method on temperatures and densities corresponding to the saturated vapor line of Lennard-Jones (LJ) liquids. While the self-diffusion coefficient, D, and shear viscosity, ηsv, increases and decreases, respectively,...
Article
Full-text available
The present study evaluates the thermal design of a blanket system using Flinabe in order to facilitate further discussions on its applicability as a self-cooled liquid blanket system. Molecular dynamics simulations were performed to evaluate the Prandtl number of mixtures in five compositions (LiF–NaF–BeF2 = 31–31–38, 36–27–37, 42–22–36, 49–16–35,...
Article
We have examined the conditions under which the breakdown of the Stokes-Einstein (SE) relation occurs in pure Lennard-Jones (LJ) fluids over a wide range of temperatures and packing fractions beyond the critical point. To this end, the temperature and packing-fraction dependence of the self-diffusion coefficient, D, and the shear viscosity, ηsv, we...
Article
Na+ ions play important roles on the physical and chemical properties of aluminosilicate glasses. It is known that they strongly modify the network of tetahedral SiO4 and AlO4 units, but the microscopic details on how they alter the local structure remain to be fully established. Here we address this issue by performing classical molecular dynamics...
Article
In order to mimic the Brownian particle in liquid, molecular dynamics calculations of dilute solutions of spherical fullerene molecules with various sizes in liquid Ar were performed. To establish the scaling equation for self-diffusion coefficient, D, of the fullerenes, the dependence of D was examined on the mass ratio of solute to solvent and on...
Article
A simple and direct evaluation method for concentration fluctuation (CF), using molecular dynamics simulation, is presented and applied to Lennard–Jones liquid mixtures and an aqueous solution of 1-propanol. The method is intuitive and straightforward, and the results are consistent with those based on the Kirkwood–Buff integrals. It enables us to...
Article
Explicit expressions of the self-diffusion coefficient, Di, and shear viscosity, ηsv, are presented for Lennard-Jones (LJ) binary mixtures in the liquid states along the saturated vapor line. The variables necessary for the expressions were derived from dimensional analysis of the properties: atomic mass, number density, packing fraction, temperatu...
Article
Full-text available
This study evaluates the physical properties of the molten salt Flinabe, using molecular dynamics simulations to discuss its applicability to a fusion blanket system. More specifically, the simulations calculate the density and viscosity of Flinabe to facilitate further discussion of the applicability from the viewpoint of the heat removal of the f...
Article
Full-text available
TiO2 and SiO2 are materials with unique importance in materials science. They are often modelled using conventional force fields, but including polarization effects is compulsory for enhancing the accuracy of the simulations. Here we parameterize a force field for the two materials in the framework of the polarizable ion model. The parameterization...
Article
A polarisable ion model is parameterised for the whole series of molten alkali halides by using first-principles calculations based on density functional theory. Viscosity, electrical conductivity and thermal conductivity are determined using molecular dynamics simulations via the Green-Kubo formulae and confronted to experimental results. The calc...
Article
An explicit expression of the Stokes-Einstein (SE) relation in molecular scale has been determined for pure Lennard-Jones (LJ) liquids on the saturated vapor line using a molecular dynamics calculation with the Green-Kubo formula, as Dη_{sv}=kTξ^{-1}(N/V)^{1/3}, where D is the self-diffusion coefficient, η_{sv} the shear viscosity, k the Boltzmann...
Article
A definition suitable for the average ionic mass used for two kinds of expressions of the thermal conductivity for molten alkali halides has been explored from the viewpoint of the difference in anion and cation masses. One is the scaling equation, \({\lambda } \propto \) \(m^{-1/2}\) \((N/V)^{2/3}\), where \({m}\) is the average ionic mass between...
Article
Full-text available
The origin of both weak temperature dependence and packing fraction dependence of T(1/4)η(3/2) in the thermal conductivity of the simple Lennard-Jones (LJ) liquid is explored. In order to discuss the relative contributions from attractive or repulsive part of the interaction potential separately, the thermal conductivity of a series of Weeks-Chandl...
Article
The thermal conductivities of molten alkali fluorides (LiF, NaF, and KF) and their mixtures (LiF–NaF, LiF–KF, and NaF–KF binaries and LiF–NaF–KF ternary) are predicted using molecular dynamics simulation with the Green–Kubo method. A polarizable ion model is used to describe the interionic interactions. All the systems except LiF–KF and LiF–NaF–KF...
Article
Dynamic structure factor of charge density was evaluated by MD simulation for molten LiI with artificially varied ionic masses. The dispersion curve was obtained from the peak frequency of collective excitation. The peak frequency at zero wavevector and the modulus of group velocity were estimated from the dispersion curves, as a function of ionic...
Article
The thermal conductivity of rare gases in liquid and dense fluid states has been evaluated using molecular dynamics simulation with the Lennard-Jones (LJ) potentials and the Green-Kubo (GK) formula. All the calculated thermal conductivities are in very good agreement with experimental results for a wide range of temperature and density. Special att...

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