Distributions of arsenic and selenium in selected Chinese coal mines.
The contents of arsenic and selenium in 33 coals collected from the main coal mines in northeastern, northern and eastern China were determined by flow injection-hydride generation and non-dispersion atomic fluorescence spectrometry (HGAFS). The concentrations of As in the northeast region are relatively higher with the values > 100 microg g(-1); in the east they are lower with values < 100 microg g(-1). The contents of Se in these three areas are the opposite, most of them from the northeast mines are < 1 microg g(-1) and increase as the mine location advances south where the average contents are > 5 microg g(-1).
Distribution and availability of arsenic in soils from the industrialized urban area of Beijing, China.
Concentrations of arsenic (As) were determined in soils of 5 industrial sites in an urban area of Beijing, China. Fifty seven typical surface soils were sampled to determine total concentrations of metals, pH and dissolved organic carbon (DOC). One hundred and eight deep soils were submitted to a four-step, sequential extraction to assess the relative mobility and bioavailability of As in the soil profiles. Total concentrations of As in surface soils ranged from 5.7 to 2.3 x 10(1) mg kg(-1), dw with greater concentrations inside the perimeter of the chemical plant which had greater concentrations than did other plants. 75.4% of surface soil samples in the industrial area contained concentrations of As that were greater than was considered to be the background concentration of 7.8 mg kg(-1), dw for the region. The mean concentration (9.9 mg kg(-1), dw) in the industrial soils was greater than that soils from other type of land use. Concentrations of As were significantly and negatively correlated with soil pH and DOC in industrial soils. Although mean concentration of total As in the soils from all sites were less at greater depths, the entire range from 0 to 180 cm (especially 0-80 cm) contained concentrations of As that were greater than background. Sequential extractions of soil indicated that only some surface soils had relatively great amount of extractable fraction of As. Most soils had relatively great amount of residual As. This result suggests that most arsenic in Beijing industrial soils should be immobile and of limited bioavailability.
Amphotericin B microspheres: A therapeutic approach to minimize toxicity while maintaining antifungal efficacy
Amphotericin B microsphere formulations with and without addition of polyethylene glycol 2000 in cross-linked bovine serum albumin were prepared. Amphotericin B microspheres were characterized for particle size (<5 µm), zeta potential (∼30 mV) and drug interaction by DSC and FTIR and were found to be stable formulations. Drug release profiles for these microspheres revealed that the release was primarily by diffusion. In vitro toxicity as assessed by release of haemoglobin and potassium demonstrated no toxic effect as compared with conventional solution formulation. Antifungal activity in vitro was comparable to solution formulation when tested by broth dilution method.