Application of water as a solvent in microwave-assisted extraction for analysis of PCBs and CBzs in fly ash

Polychlorinated biphenyls (PCBs) and chlorobenzenes (CBzs) are two classes of dioxin precursors formed in municipal solid waste incinerators (MSWIs); they produce negative health effects similar to those of dioxins. Reducing the analytical time required for determining the concentrations of these compounds in MSWIs is important for quickly evaluating their importance and assessing associated health risks. In the present study, water is used as a safe and environmentally friendly solvent in microwave-assisted extraction (MAE) for PCB and CBz analyses. MAE is compared with traditional Soxhlet extraction (SE) to determine the extraction efficiencies. The evaluation of extraction efficiencies shows that MAE has a high extraction efficiency compared with that of SE when water content is lower than 60%. Furthermore, the extraction time and organic solvent consumption are reduced with MAE compared with SE.     

Preparation of 2-fluoromalonic esters and related compounds from hexafluoropropene

Dimethyl and diethyl fluoromalonates were prepared from hexafluoropropene by its exhaustive alcoholysis or alternatively its ammonolysis and alcoholysis. Fluoromalonates thus obtained or their alkylated derivatives were condensed with o-phenylenediamine or its substituted derivatives to give a number of 1H-3-fluoro-1,5-dibenzodiazepin-2,4(3H,5H)-diones.     

Determination of chemical form of antimony in contaminated soil around a smelter using X-ray absorption fine structure.

Only limited information is available about the behavior of antimony (Sb) in contaminated soils. However, understanding the behavior of Sb in contaminated soils is important, because the toxicity or solubility of this element depends on its chemical state. In this study, we investigated the levels of Sb and the chemical forms of Sb in the soil around a smelter using X-ray absorption fine structure (XAFS) spectra. The highest Sb concentration in the contaminated soil was 2900 mg/kg dry soil. According to Sb-K edge X-ray absorption near edge (XANE) spectra, the Sb in the soil was in the form of Sb(V) compounds. The similarity of extended XAFS (EXAFS) spectra suggests that Sb speciation was independent of the sampling site, which indicates that Sb or Sb2O3 emitted from the smelter was converted into Sb(V) compounds in the soil.     

Ultramicrodetermination of nitrogen in organic compounds: VI. Capillary immutability due to glass corrosion by various solutions

The capillary immutability due to corrosion of glasses exposed to various solutions was studied. The analytical error of volume change caused by glass corrosion in a micro- and ultramicronitrometer was discussed. The present work has shown that the graduated tube of a decimicronitrometer made of borosilicate glass, which is used frequently in Dumas method, should be recalibrated after 1.5–2.3 months use. We therefore recommend the sealed tube method using an improved nitrometer for ultramicrodetermination of nitrogen in organic compounds.     

90 degrees phase-matched third-harmonic generation of CO(2) laser frequencies in AgGa(1-x)In(x)Se(2)

AgGa(1-x) In(x)Se(2) with x=0.474 was found to be 90 degrees phase matchable for third-harmonic generation of CO(2) laser wavelengths 9.2714-10.5910 mum by means of temperature tuning. Sellmeier equations and the thermo-optic constant for this crystal are presented.     

Quantum oscillation of carrier concentration due to fermi level pinning by doped indium impurities in Pb1−XSnXTe

The Shubnikov-de Haas like oscillation and rapid increase of the carrier concentration above the quantum limit magnetic field (H₀) are observed in Pb_1?xSn_xTe doped with indium (x=0.33 and 0.35). Experimental results can be reproduced satisfactorily by the calculation based on the Fermi level pinning model due to In-impurities, where we take into account the level broadening (Г) effect of the band structure. It is confirmed that the increasing rate of carrier concentration with respect to magnetic field above H₀ decreases with larger Г.