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Classical molecular dynamics (MD) is used to simulate atomic layer etching processes of silicon by alternating exposure to chlorine gas and argon ions. In order to validate our model, a rigorous comparison is done with ion beam experiments found in the literature [Park et al., Jpn. J. Appl. Phys. 44, 389 (2005)]. It is shown that the etch per cycle (EPC) as a function of argon ion energy from simulations is in quantitative agreement with experimental results if the correct argon ion fluence is used in the simulations. The EPC as a function of ion irradiation time and amount of chlorine exposure also show good agreement with the experiment. The MD simulations also show the formation of an amorphous silicon region with chlorine atoms mixed uniformly throughout following ion bombardment. Finally, the etch products during the ion irradiation step are analyzed and discussed. [ABSTRACT FROM AUTHOR]

Nateglinide (NAT) and Pioglitazone (PIO) are an antidiabetic drugs combination and currently under clinical trial in countries like Japan. In this study, an alternative, a simple, sensitive high-performance liquid chromatography method has been developed (limit of detection: 15 ng/mL and limit of quantification: 50 ng/mL) for simultaneous estimation of this drug combination in rat plasma. Most remarkably, bioavailability of NAT has been increased markedly on coadministration with PIO, than when it was administered alone. Thus, PIO is assumed to retard the catabolism of NAT by inhibiting metabolic liver-microsomal enzyme, especially CYP2C9. Using a Waters Nova-Pak C 18 column (150 × 3.9 mm, 4 μm) and a mobile phase of acetonitrile: 10 mM KH2PO4 (60: 40, V/V (volume by volume)) pH 3.5, the analysis was performed at 210 nm with a flow rate of 1.5 mL/min. In silico docking via molecular dynamics simulation revealed that NAT-CYP2C9 binding affinity may be reduced after PIO attachment, presumably due to the binding site overlapping of the two drugs. Thus, it has been proposed that NAT and PIO may be an efficient synergistic fixed dose combination against diabetes mellitus, and the above method can foster a simple but highly sensitive bioanalytical estimation for routine analysis. [ABSTRACT FROM AUTHOR]

Solution chemistry of Co(II) is receiving a renewal attention due to the high interest for knowing the speciation in seawater of its 60 Co radioactive isotope which appeared in the Japan sea as a consequence of the Fukushima-Daichii nuclear power plant accident. Experimental EXAFS and XANES spectra of a dilute Co(II) aqueous solution have been recorded and structural data derived from their analysis. Based on QM calculations, an ab-initio intermolecular potential has been generated for the Co(II)–H 2 O interaction using the hydrated ion model that uses a polarisable and flexible solvent description through the MCDHO2 model. Classical molecular dynamics simulations of Co(II) in water have been performed and X-ray Absorption spectra have been simulated and compared with the experimental ones. Energetic, structural, dynamical and spectroscopical properties of the cobalt cation in solution have been computed and compared with previous experimental and theoretical data. These comparisons have assessed the good performance of the developed intermolecular potential. [ABSTRACT FROM AUTHOR]

The seventh U.S.-Japan Joint Seminar on Nanoscale Transport Phenomena was held in Shima, Japan, from December 11 to 14, 2011. The goals of this joint seminar were to provide a critical assessment of the state of the art and future directions in the field of nanoscale transport phenomena and energy conversion processes, to foster U.S.-Japan col-laborations, and to provide international exposure to a new generation of scientists in this field Issues discussed in the joint seminar were organized in 10 topical sessions, includ-ing (1) nanoscale thermophysical measurements; (2) optical characterization; (3) thermal and molecular transport; (4) phonon transport modeling; (5) energy storage and conversion; (6) nanoscale fluidics and phase change phenomena; (7) biological and organic systems; (8) interfacial thermal transport; (9) novel thermoelectric and thermal management mate-rials; and (10) nanocarbon materials and devices. In addition to these topical sessions, the joint seminar featured an opening plenary session and a closing plenary session as well as an expert panel, where leading experts provided critical assessment of the past progress and addressed future directions in the field. In addition, an evening poster session provided opportunities for graduate and postdoc students to present their latest research results. About 35 researchers from Japan and 31 researchers from the United States participated in the meeting. The meeting was organized by S. Maruyama, K. Fushinobu, L. Shi, and J. Lukes together with about 20 other participants who served as session chairs. Summaries of dif-ferent sessions of the seminar were prepared by the session and conference chairs and are collected into this report. [ABSTRACT FROM AUTHOR]

Measurements of ultrafine particles (UFPs) with diameters smaller than 100 nm were made with a Scanning Mobility Particle Sizer on the roadside of the Tateyama-Kurobe Alpine route on the western slope of Mt. Tateyama, Japan, in the summer and autumn of 2007 and 2008. The number concentrations of nanoparticles (NPs) with diameters smaller than 50 nm increased sharply in the morning. This increase agreed with that of the NO concentration, which is a good indicator of vehicle emissions. Although the peak concentration of NO was also detected in the late afternoon, the concentrations of NPs did not increase. The vehicle emission of UFPs may vary considerably with the driving conditions. The emission of NPs might have been accelerated under a high engine-load condition. The NP concentrations in October were much higher than those in August, although there were more buses in August than in October. The number size distribution in the morning was bimodal, with the first peak around 20-30 nm and the second one around 70-80 nm. The first peak became small during the daytime. The first peak disappeared, and a small second peak remained through midnight. [ABSTRACT FROM AUTHOR]

The variability of atmospheric mercury in elemental, reactive, and particulate forms has been studied at a remote site (Cape Hedo Observatory, CHO) at Okinawa Island (Japan) March 23 to May 2, 2004, downwind of the major Asian source regions. Under prevailing meteorological conditions, episodes of higher levels of atmospheric mercury and other atmospheric species are observed at CHO. The mean (±1σ) concentrations of gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particulate-bound mercury (PHg) are 2.04±0.38ngm−3, 4.5±5.4pgm−3 and 3.0±2.5pgm−3, respectively. In Asian outflow the combined contribution of RGM and PHg constitutes less than 1% of the GEM in the boundary layer, which indicates that most mercury export in the marine boundary layer is due to the GEM form, and direct outflow of RGM and PHg is very low. While the data from Okinawa suggest minimal export of RGM and PHg, this does not preclude greater export of these species at higher elevations. Based on the correlations of PHg and submicron aerosol mass (SAM), we found a ΔPHg/ΔSAM ratio of 0.20μgg−1 (R =0.58, p <0.01), which we believe to be characteristic of East Asian industrial aerosols during outflow. A diurnal variation is observed in RGM with a peak near noon. Using a rate constant of 9×10−14 cm3 molecule−1 s−1 for the OH oxidation rate (Sommar, J., Gardfeldt, K., Stromberg, D., Feng, X., 2001. A kinetic study of the gas phase reaction between the hydroxyl radical and atomic mercury. Atmospheric Environment 35, 3049–3054; Pal, B., Ariya, P.A., 2004a. Gas-phase HO center dot-initiated reactions of elemental mercury: kinetics, product studies, and atmospheric implications. Environmental Science and Technology 38 (21), 5555–5566.) and a typical OH concentration of 1–5×106 cm−3 would result in RGM production rates of 0.6–3.0pgm−3 h−1. Although OH may not be the sole oxidant, this is consistent with the observed change in concentration during daytime of 1.4±1.5pgm−3 h−1. A significant correlation is found between GEM and CO; GEM and SAM; and PHg and SAM. Lower ΔSAM/ΔCO and ΔGEM/ΔCO are observed for transport events with rainfall and for air parcels remaining in the mixed layer. Back trajectory analysis along with the correlation study suggests that the air from China has a higher GEM concentration compared to the air coming from southern Japan. [Copyright &y& Elsevier]

Molecular dynamics (MD) studies have been playing a major role in this fast expanding research field of microscale thermophysical engineering in Japan. MD simulation is very effective for setting up a simplified ideal situation to examine the fundamental mechanism of thermal phenomena. On the other hand, when researchers try to solve complex problems at the stage of practical application, they face difficulties that are coming from the scale gap between the phenomena and the molecular system that can be treated by MD. In the present article, efforts that are being made to overcome these difficulties are discussed along with an overview of current hot topics in Japanese MD research. [ABSTRACT FROM AUTHOR]

Abstract: The suite of neutron spectrometers under construction or proposed for the Materials and Life Science Facility at J-PARC (Tokai, Ibaraki, Japan) will provide opportunities for strengthening and expanding research on the molecular dynamics of biomolecules. Following a brief discussion of the current state of work and the likely impact of fast spectrometers, this paper draws attention to the need for tackling some methodological problems, outlines problem areas opened up by the reduction in sample sizes, and addresses the potential for projects of biomedical and biotechnological relevance. [Copyright &y& Elsevier]

We have examined a possibility of using canonical ensemble molecular dynamics (NVT-MD) simulation to prepare the solvent-solvent correlation function (VVCF), which is further utilized in the calculation of solute-solvent correlation function for the solvation free energy (SFE) of the Lennard-Jones (LJ) solution at the infinite dilution. We have employed a combined closure equation where the radial distribution function (RDF) of NVT-MD simulation is used for the short range and the hypernetted chain (HNC) closure for the long range. An appropriate separation for the boundary to switch the RDF of the MD simulation and the HNC closure is determined from the balance between the accuracy of the compressibility equation and the numerical stability. The appropriate separation is found to be from 2.0 to 3.0 in the unit of the LJ particle size. Furthermore, the isothermal compressibility evaluated from the combined NVT-MD closure agrees with those evaluated from the volume fluctuation in the isobaric isothermal ensemble MD simulation. The VVCF obtained from the combined NVT-MD closure is further used in the assessment of the sigma enlarging bridge (SEB) function that was proposed in our earlier works, e.g. [T. Miyata, Bull. Chem. Soc. Japan, 90 (2017) 1095], with which the first rising region of the RDF obtained from an approximate Ornstein-Zernike theory can be corrected by apparently adjusting (typically enlarging) the sigma parameters in the LJ potential. The following two points of view are considered in the assessment of the SEB function. One is the isothermal compressibility of the solvent, and the other is the SFE. It is found that the Kovalenko-Hirata closure with the SEB correction provides rather accurate VVCF, which leads to an accurate isothermal compressibility. The SFE is also improved when we apply the SEB correction to the solute-solvent calculation. While the SEB function includes one parameter, the numerical values of it are parameterized over a wide range of conditions in this study under the usage of the combined NVT-MD closure for the solvent-solvent calculation. Unlabelled Image • Solvent-solvent correlation function is prepared using canonical ensemble molecular dynamics simulation. • Quality of the prepared solvent-solvent correlation function is judged in terms of the compressibility equation. • Direct correlation function under SEB-HNC and SEB-KH closures is examined in terms of its accuracy. • Improving only the solvent-solvent correlation function fails to accurately evaluate the solvation free energy. • Parameters included in the SEB function are numerically evaluated in a wide range of conditions. [ABSTRACT FROM AUTHOR]

The article provides information on several of the nominees for the Society of Polymer Science, Japan Award for the Outstanding Paper in Polymer Journal 2005. Papers nominated include "Molecular Dynamics Study of the Adhesion between End-grafted Polymer Films," by Hiroshi Morita and "Room-Temperature Polycondensation of Dicarboxylic Acids and Diols Catalyzed by Water-Stable Lewis Acids," by Akinori Takasu .