Collisionless reconnection in an electron-positron plasma

Electromagnetic particle-in-cell simulations of fast collisionless reconnection in a two-dimensional electron-positron plasma (without an equilibrium guide field) are presented. A generalized Ohm's law in which the Hall current cancels out exactly is given. It is suggested that the key to fast reconnection in this plasma is the localization caused by the off-diagonal components of the pressure tensors, which produce an effect analogous to a spatially localized resistivity.     

Synthesis of 2-amino-2-deoxo-5-deazaflavins and related compounds

10-Alkyl-2-amino-2-deoxo-5-deazaflavins were prepared by the condensation of 2-amino-6-chloro-5-formylpyrimidin-4(3H)-one with the corresponding N-alkylanilines. 2-Amino-10-p-tolyl-2-deoxo-5-deazaflavin was prepared by the condensation of 2-amino-6-p-toluidinopyrimidin-4(3H)-one with o-chlorobenzaldehyde. Some reactivities of 2-aminopyrimidin-4(3H)-ones are described.     

Synthesis of copper monolayer and particles at aqueous–organic interface

Using aqueous–organic interface (water–oleic acid) reduction of Cu²⁺ by ascorbic acid, hydrophobic copper monolayer and copper particles have been prepared and characterized. The resultant monolayer could be transferred from the interface onto solid substrate or be dissolved to yield an organosol and copper nanoparticles.     

Vertical Distribution of Particulate Mercury as Measured on a Meteorological Observation Tower (213m)

Abstract

The concentration of mercury in airborne particles was determined in samples collected at heights of 1m and at 175m up the Meteorological Observation Tower (213m) at the Meteorological Research Institute, Tsukuba between August 1985 and April 1986. The concentrations of particulate mercury at the two heights were compared with gaseous mercury levels at a height of 10m and with other chemical components in the particles. The concentrations of particulate mercury at both heights showed no positive correlation with those of gaseous mercury, total suspended particles, sulfate, chloride, sodium or calcium. However, there was some positive correlation between particulate mercury and nitrate concentrations especially at 175m; the concentrations of these components were found to be high when the wind direction was southwesterly. These results suggest that these components were transported from the Tokyo Metropolitan area.     

Tritium activity induced in the accelerator building and its correlation to radioactivity of gamma-nuclides

An infrared furnace (ULVAC RHL-410P) was newly applied to the extraction of tritium from concrete samples. After studying the tritium recovery yield regarding temperature and time, the best extraction conditions were set to 800 °C (setting temperature) for 30 minutes under Ar-gas flow of 200 ml/min. Tritium was collected in two cold traps and transferred to a vial for liquid scintillation counting. It took about one hour for the extraction of tritium. Reproducibility and recovery yield of tritium were about 100% compared to the values obtained by the ordinary heating method using an electric furnace. Gamma-ray emitters and tritium of concrete samples collected from several accelerator facilities have been determined. The specific activity of tritium strongly correlated with that of ¹⁵²Eu and ⁶⁰Co, so it was found that tritium was produced by thermal neutron reaction by the ⁶Li(n,)³H reaction. The results indicate that the tritium specific activity in concrete can be estimated from the ⁶⁰Co specific activity obtained easily by -ray measurement.On leave from IHEP, Beijing.This work was supported by Japan Society for the Promotion of Science. The authors also are grateful to Dr. S. Watanabe, Center for Nuclear Study, University of Tokyo, Dr. T. Ohtsuki, Laboratory of Nuclear Science, Tohoku University, and Dr. T. Saito, Research Center for Nuclear Physics, Osaka University, and their colleagues for concrete sampling.     

Combined experimental and DFT-TDDFT computational study of photoelectrochemical cell ruthenium sensitizers

We report a combined experimental and computational study of several ruthenium(II) sensitizers originated from the [Ru(dcbpyH(2))(2)(NCS)(2)], N3, and [Ru(dcbpyH(2))(tdbpy)(NCS)(2)], N621, (dcbpyH(2) = 4,4'-dicarboxy-2,2'-bipyridine, tdbpy = 4,4'-tridecyl-2,2'-bipyridine) complexes. A purification procedure was developed to obtain pure N-bonded isomers of both types of sensitizers. The photovoltaic data of the purified N3 and N621 sensitizers adsorbed on TiO(2) films in their monoprotonated and diprotonated state, exhibited remarkable power conversion efficiency at 1 sun, 11.18 and 9.57%, respectively. An extensive Density Functional Theory (DFT)-Time Dependent DFT study of these sensitizers in solution was performed, investigating the effect of protonation of the terminal carboxylic groups and of the counterions on the electronic structure and optical properties of the dyes. The calculated absorption spectra are in good agreement with the experiment, thus allowing a detailed assignment of the UV-vis spectral features of the two types of dyes. The computed alignments of the molecular orbitals of the different complexes with the band edges of a model TiO(2) nanoparticle provide additional insights into the electronic factors governing the efficiency of dye-sensitized solar cell devices.     

Development of a Sensitive Luminometric Immunoassay for Determining Baseline Seasonal Changes in Serum Vitellogenin Levels in Male Flounder (Pleuronectes Yokohamae)

Abstract

Vitellogenin is a sensitive biomarker used to study the effects of artificial estrogens in aquatic environments. We developed and optimized a luminometric immunoassay that was able to detect trace amounts of vitellogenin in the serum of male flounder collected from an uncontaminated reference site. The lowest measurable concentration of vitellogenin in the serum was approximately 0.08 ng/ml with purified protein diluted in buffer. The reproducibility of the vitellogenin measurements was determined by the analysis of triplicate samples and found to be about 5.3%, based on serum samples containing vitellogenin at 2.0 ng/ml. This method was successfully applied to samples collected from an uncontaminated reference site for the monitoring of baseline levels of serum vitellogenin in male flounder.