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The chemical composition and pH of 30 fresh snow samples collected during December 1986 to May 1987 at Gulmarg (34 degrees 03' N, 74 degrees 24' E, 2655 m above mean sea level), a remote place in north India, were studied. The snow samples were, by and large, alkaline in nature and were largely influenced by non-marine aerosols. The concentrations of cations (Ca(2+), K(+) and Mg(2+)) were more than the anions (SO(2-)(4) and NO(-)(3)). Factor analysis indicated that most of the ionic components were transported into the region during the period of measurements. The transport of ionic components could be attributed to the passage of western disturbances over this region. The comparison of concentrations of anions and cations in the snow samples at Gulmarg with those reported from a few countries in the west revealed that the composition of Gulmarg snow largely differs in the concentrations of cations rather than anions. Among the cations, the concentration of Ca(2+) was high at Gulmarg and this could be responsible for buffering the pH of snow in the alkaline range.  相似文献   
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Abstract

Plasma processing has been identified as a useful tool for immobilizing heavy metal-contaminated wastes into safe, leach-resistant slag. Although much effort has gone into developing this technology on a pilot scale, not much information has been published on basic research topics. A laboratory-scale plasma arc furnace located at the University of Illinois was operated in cooperation with the U.S. Army Construction Engineering Research Laboratories in an effort to establish an understanding of the chemical and physical processes (such as metal volatilization and resultant gas evolution) that occur during thermal plasma treatment of metal-spiked samples. Experiments were conducted on nickel and chromium using a highly instrumented furnace equipped with a 75 kW transferred arc plasma torch. The volatility of nickel and chromium was examined as a function of varying oxygen partial pressures. Oxidizing conditions reduced the total dust gathered for both the nickel and chromium samples, although each dust sample was found to be metal-enriched. Plasma treating increased the leach-resistance of the slags by at least one order of magnitude when compared to unprocessed specimens. The leach- resistance of the nickel-containing slags increased in the presence of oxygen, whereas chromium samples remained relatively constant.  相似文献   
3.
In an effort to test the hypoglycemic activity of Aegle marmelos and Hibiscus rosa sinensis in glucose induced hyperglycemic rats, their alcoholic leaf extracts were studied. Both the groups of animals receiving either. A. marmelos or H. rosa sinensis leaf extract for seven consecutive days, at an oral dose equivalent to 250 mg kg-1 showed significant improvements in their ability to utilize the external glucose load. Average blood glucose lowering caused by A. marmelos and H. rosa sinensis was 67% and 39% respectively, which shows that former significantly (p < 0.001) improves the glucose tolerance curve. The magnitude of this effect showed time related variation with both the plants. Efficacy of A. marmelos and H. rosa sinensis was 71% and 41% of glybenclamide, respectively. These data throw some light on the possible mechanism of hypoglycemic activity of both the plants. The mechanism of action could be speculated partly to increased utilization of glucose, either by direct stimulation of glucose uptake or via the mediation of enhanced insulin secretion.  相似文献   
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