Analysis of atmospheric sulfur gases by capillary gas chromatography with atomic emission detection

The atomic emission detector (AED) has been found to be a sensitive and selective instrument for analysis of atmospheric sulfur gases by capillary gas chromatography. It was possible to determine atmospheric dimethyl sulfide at concentrations below 0.3 nmol/m³ typical of the remote marine environment in winter. Sample analyses from the Australian Baseline Air Pollution Station, Cape Grim, are used to illustrate this. In comparison with other sulfur-specific detectors previously used for this work, the AED has been found to exhibit the best combination of specificity and sensitivity. A configuration comprising a series of valves, gas calibration loops, and a cryogenic trap prior to the GC-AED was used for sample analysis. Standard addition of sulfur hexafluoride was found to assist determination of carbonyl sulfide, as it could be used to take into account the magnitude of signal quenching from coeluting gases. The AED was also found to be a selective detector for the direct injection of water-soluble dimethyl sulfide oxidation products.     

Effects of Adsorbed Polyaniline on Redox Processes on As(2)O(3) Surfaces

Polyaniline deposited on As(2)O(3) surface resulted in a new material, which was characterized by infrared spectoscopy, thermogravimetry, differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and cyclic voltammetry. The mass percentage of polymer deposited on oxide surface is approximately 13%. The scanning electron microscopy images as well as the X-ray diffraction patterns provided conclusive evidence that the oxide surface is coated by the polymer. The cyclic voltammograms of the polyaniline adsorbed on As(2)O(3) surface showed that the adsorbate exerts remarkable effects on redox processes on this oxide. The pure oxide exhibited two oxidation/reduction peaks at 0.25/-0.06 and 0.47/-0.25 V attributed tentatively to the processes As(2)O(3)(s)+6H(+)+6e(-)=2As(s)+3H(2)O and As(s)+3H(+)+3e(-)=AsH(3)(g), respectively. The polyaniline-coated sample exhibited a better-defined voltammogram in which the first oxidation peak of the oxide had its intensity increased about four times. Copyright 2000 Academic Press.     

Status of electroweak phase transition and baryogenesis

I review recent progress on the electroweak phase transition and baryogenesis, focusing on the minimal supersymmetric Standard Model as the source of new physics.