Continuous-flow asymmetric biomimetic transamination

This study has demonstrated that conceptually new continuous-flow reaction procedure for biomimetic transamination of perfluoroalkyl-containing ketones is substantially more efficient as compared with conventional in-flask approach, allowing preparation of the target fluorinated amines with generally improved chemical yields and enantioselectivity.     

Cyclotron resonance of positive holes in AgBr

The first observation of cyclotron resonance of holes in AgBr is reported. Measurements have been made at 34 GHz and 1.7 K. It is shown that the energy surfaces for the hole polaron consist of a set of spheroids oriented along the [111] directions with the mass parameters $\text{m}{}^1{}_{\mathrm{l}}\text{= (1.71±0.06)m}{}_0$ and $\text{m}{}^1{}_{\mathrm{t}}\text{=(0.79±0.01)m}{}_0$. The mobility of the hole polaron is determined to be about $\text{1.5 × 10}{}^5\text{cm}{}^2\text{Vsec}$ at 1.7 K.     

Anisotropy in conductance of a quasi-one-dimensional metallic surface state measured by a square micro-four-point probe method

We have devised a "square micro-four-point probe method" using an independently driven ultrahigh-vacuum four-tip scanning tunneling microscope, and succeeded for the first time to directly measure anisotropic electrical conductance of a single-atomic layer on a solid surface. A quasi-one-dimensional metal of a single-domain Si(111)4 x 1-In had a surface-state conductance along the metallic atom chains (sigma(axially)) to be 7.2(+/-0.6) x 10(-4) S/square at room temperature, which was larger than that in the perpendicular direction (sigma(radially)) by approximately 60 times. The sigma(axially) was consistently interpreted by a Boltzmann equation with the anisotropic surface-state band dispersion, while the sigma(radially) was dominated by a surface-space-charge-layer conductance.     

Electron-phonon interaction and localization of surface-state carriers in a metallic monolayer

Temperature-dependent electron transport in a metallic surface superstructure, Si(111)sqrt[3] x sqrt[3]-Ag, was studied by a micro-four-point probe method and photoemission spectroscopy. The surface-state conductivity exhibits a sharp transition from metallic conduction to strong localization at approximately 150 K. The metallic regime is due to electron-phonon interaction while the localization seemingly originates from coherency of electron waves. Random potential variations, caused by Friedel oscillations of surface electrons around defects, likely induce strong carrier localization.     

Inhomogeneity of local temperature in small clusters in microcanonical equilibrium

Overall homogeneity of temperature is a condition for thermal equilibrium, but, as is demonstrated by classical molecular dynamics simulations, the local temperatures of atoms in small, isolated crystalline clusters in microcanonical equilibrium are not uniform. The effective temperature determined from individual atomic velocity decreases with distance from the cluster center. It is argued that these effects are due to the conservation of angular and translational momentum. A general microcanonical expression is derived for the spatial dependence of the statistics of the kinetic energies of individual atoms; this fits the numerical observations well.     

Phagocytic activity of alveolar macrophages toward polystyrene latex microspheres and PLGA microspheres loaded with anti-tuberculosis agent

Phagocytosis of alveolar macrophages (Ms) toward poly(lactic-co-glycolic acid) (PLGA) microspheres (MS) loaded with the anti-tuberculosis agent rifampicin (RFP-PLGA MS) has been shown to be effective for the treatment of tuberculosis. The phagocytosis should be evaluated in terms of that toward reference MS. We chose polystyrene latex (PSL) MS as a reference. In this study, phagocytic activity of cell line NR8383, derived from rat alveolar M, toward PSL MS with various diameters was examined by incubating the cells for 4 h at 37 °C with various numbers of PSL MS per M cell (MS/M = 0.1–10). The results were then compared with those of the phagocytosis toward RFP-PLGA MS. We determined the phagocytic activity by counting the population of M cells that had phagocytosed MS (N) and the number of particles phagocytosed (n) in microscopic fields. Both N and n for PSL and RFP-PLGA MS increased in general with an increase in MS/M, but both of these values for PSL MS were smaller than those for RFP-PLGA MS. Phagocytosis of the particles were dependent on the particle size; i.e., of the PSL MS the 6-μm ones were taken up by M the most, and the RFP-PLGA MS 3 μm in diameter seemed to be phagocytosed the most efficiently, although we were not able to determine exactly the phagocytosis of 6- and 10-μm RFP-PLGA MS. From the changes in N and n values with MS/M, the phagocytosis of RFP-PLGA MS was likely to enhance the phagocytic activity of M cells, but this effect did not seem to be significant for PSL MS.