Mesoscale modeling of colloidal suspensions with adsorbing solutes

We construct a mesoscale model of colloidal suspensions that contain solutes reversibly adsorbing onto the colloidal particle surfaces. The present model describes the coupled dynamics of the colloidal particles, the host fluid, and the solutes through the Newton-Euler equations of motion, the hydrodynamic equations, and the advection-diffusion equation, respectively. The solute adsorption is modeled through a square-well potential, which represents a short-range attractive interaction between a particle and a solute molecule. The present model is formulated to be solved through direct numerical simulations. Some numerical results are presented to validate the simulations. The present model enables investigations of solute adsorption effects in the presence of a fluid flow and an inhomogeneous solute concentration distribution.Comment: 9 pages, 7 figure

Inelastic Neutron Scattering Study of Ferroelectric Phase Transition in Lithium Heptagermanate (Li(2)Ge(7)O(15))

Phonon dispersions in ferroelectric lithium heptagermanate Li(2)Ge(7)O(15) (LGO) were measured by inelastic neutron scattering in the vicinity of the transition temperature T(C) = 283.5 K. The (300) reflections show more pronounced temperature dependence than the (500) reflections. The energy of a peak corresponding to the Brillouin zone-center phonon, around 0.5 meV at 297.0 K, decreases as the temperature decreases. Then, this inelastic component disappears into the central component at 288.0 K, just above T(C). The present phonon shows the typical soft mode feature and shows good accordance with the B(1u) mode observed by hyper-Raman and FTIR measurements. It is confirmed that the ferroelectric phase transition in LGO is associated with the soft optical phonon at the zone center. Moreover, elastic diffuse scattering is observed below 0.1 meV. This implies that there exists a critical phenomenon at energies below than 0.1 meV.ArticleFERROELECTRICS. 412(0):45-51 (2011)journal articl

超臨界CO2－CO2 カスケード式冷凍システムによる高効率冷凍機の開発

学位記番号：理工博乙5

RELATIONSHIP BETWEEN ANTERIOR TIBIAL TRANSLATION AND ISOMETRIC STRENGTH IN FEMALE ATHLETES

The purpose of this study was to determine whether the isometric strength of the muscles around the knee and hip is associated with anterior tibial translation. Forty-four female high school basketball players participated in this study. Anterior tibial translation was measured with a Kneelax 3 arthrometer. The isometric strengths of knee flexion, knee extension, and hip abduction were determined with a hand-held dynamometer. In the case of both the legs, significant correlations were found between the anterior tibial translation, knee extension strength, and hamstring/quadriceps strength (H/Q) ratio. No significant correlations were found between the anterior tibial translation and the knee flexion and hip abduction strengths. Muscle imbalance between the quadriceps and hamstring muscles may lead to greater anterior tibial translation

Millimeter-Thick Single-Walled Carbon Nanotube Forests: Hidden Role of Catalyst Support

A parametric study of so-called "super growth" of single-walled carbon nanotubes(SWNTs) was done by using combinatorial libraries of iron/aluminum oxide catalysts. Millimeter-thick forests of nanotubes grew within 10 min, and those grown by using catalysts with a thin Fe layer (about 0.5 nm) were SWNTs. Although nanotube forests grew under a wide range of reaction conditions such as gas composition and temperature, the window for SWNT was narrow. Fe catalysts rapidly grew nanotubes only when supported on aluminum oxide. Aluminum oxide, which is a well-known catalyst in hydrocarbon reforming, plays an essential role in enhancing the nanotube growth rates.Comment: 11 pages, 3 figures. Jpn. J. Appl. Phys. (Express Letters) in pres

Drift-Induced Step Instabilities Due to the Gap in the Diffusion Coefficient

On a Si(111) vicinal face near the structural transition temperature, the $1 \times 1$ structure and the $7 \times 7$ structure coexist in a terrace: the $1 \times 1$ structure is in the lower side of the step edge and the $7 \times 7$ structure in the upper side. The diffusion coefficient of adatoms is different in the two structures. Taking account of the gap in the diffusion coefficient at the step, we study the possibility of step wandering induced by drift of adatoms. A linear stability analysis shows that the step wandering always occurs with step-down drift if the diffusion coefficient has a gap at the step. Formation of straight grooves by the step wandering is expected from a nonlinear analysis. The stability analysis also shows that step bunching occurs irrespective of the drift direction if the diffusion in the lower side of the step is faster. The step bunching disturbs the formation of grooves. If step-step repulsion is strong, however, the step bunching is suppressed and the straight grooves appear. Monte Carlo simulation confirms these predictions.Comment: 5 pages, 6 figure

siRNA-dependent and -independent post-transcriptional cosuppression of the LTR-retrotransposon MAGGY in the phytopathogenic fungus Magnaporthe oryzae

The LTR-retrotransposon MAGGY was introduced into naive genomes of Magnaporthe oryzae with different genetic backgrounds (wild-type, and MoDcl1 [mdl1] and MoDcl2 [mdl2] dicer mutants). The MoDcl2 mutants deficient in MAGGY siRNA biogenesis generally showed greater MAGGY mRNA accumulation and more rapid increase in MAGGY copy number than did the wild-type and MoDcl1 mutants exhibiting normal MAGGY siRNA accumulation, indicating that RNA silencing functioned as an effective defense against the invading element. Interestingly, however, regardless of genetic background, the rate of MAGGY transposition drastically decreased as its copy number in the genome increased. Notably, in the MoDcl2 mutant, copy-number-dependent MAGGY suppression occurred without a reduction in its mRNA accumulation, and therefore by a silencing mechanism distinct from both transcriptional gene silencing and siRNA-mediated RNA silencing. This might imply that some mechanism possibly similar to post-transcriptional cosuppression of Ty1 retrotransposition in Saccharomyces cerevisiae, which operates regardless of the abundance of target transcript and independent of RNA silencing, would also function in M. oryzae that possesses the RNA silencing machinery