Convertible source system of thermal neutron and X-ray at Hokkaido University electron linac facility

The convertible source system for the neutron and the X-ray imagings was installed in the 45MeV electron linear accelerator facility at Hokkaido University. The source system is very useful for a complementary imaging. The imaging measurements for a sample were performed with both beams by using a vacuum tube type image intensifier. The enhanced contrast was obtained from the dataset of the radiograms measured with the neutron and X-ray beams

Molecular dynamics simulation of observed c(4x4) and c(4x3) C60 alignments on the Si(100) reconstructed surface.

We have implemented a large-scale classical molecular dynamics simulation at constant temperature to provide a theoretical insight into the results of a recently performed experiment on the monolayer and multi-layer formations of molecular films on the Si(100) reconstructed dimerized surface. Our simulation has successfully reproduced all of the morphologies observed on the monolayer film by this experiment. We have obtained the formation of both c(4 4) and c(4 3) structures of the molecules and have also obtained phase transitions of the former into the latter

Amelioration of normothermic canine liver ischemia with prostacyclin.

A model of hepatic ischemia was developed in dogs using a pump-driven splanchnic-to-jugular vein bypass during crossclamping of the portal triad. An LD50 was established with three hours of ischemia. PGI2 given for one hour before the ischemic insult ameliorated the ischemic injury and increased survival

Point defect dynamics in bcc metals

We present an analysis of the time evolution of self-interstitial atom and vacancy (point defect) populations in pure bcc metals under constant irradiation flux conditions. Mean-field rate equations are developed in parallel to a kinetic Monte Carlo (kMC) model. When only considering the elementary processes of defect production, defect migration, recombination and absorption at sinks, the kMC model and rate equations are shown to be equivalent and the time evolution of the point defect populations is analyzed using simple scaling arguments. We show that the typically large mismatch of the rates of interstitial and vacancy migration in bcc metals can lead to a vacancy population that grows as the square root of time. The vacancy cluster size distribution under both irreversible and reversible attachment can be described by a simple exponential function. We also consider the effect of highly mobile interstitial clusters and apply the model with parameters appropriate for vanadium and $\alpha-$iron.Comment: to appear in Phys. Rev.

A Mechanism of 13% Lattice Expansion in C_<60> FCC(110) Thin Films Grown on the GaAs(001) As-rich Surface

We perform a classical molecular dynamics simulation, a first-principle calculation based on LDA, and moreover a simple theoretical analysis to examine the very interesting crystalographic structure of the first layer and overlayer C_s adsorbed on the As-rich substrate of the GaAs(001) surface, which was recently observed with the STM by our group. From the classical molecular dynamics study, we reproduce the pairwise structure of C_ adsorbed in the first layer. On the other hand, from the first-principle study, we estimate how much the charge transfer is from the underlayer As atoms to the C_s adsorbed in the first layer. We found that the amount of this charge transfer is large enough to expect that the strong dipole field caused by this dipole layer at the interface induces dipole moments in the C_s adsorbed on overlayers and that the resulting dipole-dipole interaction among the overlayer C_ molecules is the origin of the 13% lattice expansion of the overlayer C_ fcc thin film observed experimentally

Electromagnetic lateral control system of floating strip

Strip floating system is effective to avoid strip wrinkles and defects caused by roll contact, and to keep high quality of steel strip in the continuous processing lines.In development of the floating system, challenging point is its controller against lateral instability of the floating strip supported by air cushion devices. We developed the electromagnetic control system, whose response is much quicker than that of the conventional center position control (CPC) system using rollers. This paper shows validity of our new control system

Synthesis and Characterization of Stoichiometric Spinel-LiMn₂O₄

In this study, spinel LiMn2O4 powder was synthesized from LiOH.H2O and MnOx by conventional and mechanical alloying (MA) methods, followed by heat treatment at 800 °C in O2 for four hours with cooling to room temperature in the furnace at 60 °C/h. It is found that both samples do not show phase transition in low temperature, and this occurred for different reasons. In the MA sample, the presence of Fe as contamination increased the Mn valence and hindered the occurrence of phase transition. The conventional sample does not show phase transition at low temperature due to stoichiometric content, without any contamination. In general, the absence of phase transition occurred due to synthesis condition employed in this study.</span