Organochlorine insecticide residues in the rain water in Delhi,India

Rain water samples were regularly collected from three sites, namely, Netaji Nagar, Moti Nagar and Town Hall within the Delhi city area from July, 1980 to June, 1982. The pesticide residues were adsorbed on polyurethane foam coated with 0.5 % DC-200 and subsequently extracted and analyzed for DDT, HCH and their metabolites/isomers. The concentration of total DDT ranged from 0.22 to 108 μg L^?1 with a mean value of 12.5 μg L^?1. The samples of rain water contained varying levels of 4,4-DDT, 2,4-DDT, 4,4-DDE, and 4,4-DDD. The 4,4-DDT, 4,4-DDE and 2,4-DDT were the main components of total DDT. The range of HCH residues in rain water was from 0.08 to 43 μg L^?1 with a mean of 5.3 μg L^?1. The residues of HCH consisted mainly of α- and γ-isomers with traces of β and δ-isomers. The α- and γ-isomers accounted for 76 and 24% of total HCH, respectively. The concentrations of DDT and HCH in rain water were generally less than 10 μg L^?1 and exceeded 10 in only 4 and 3 cases, respectively. The residues of these insecticides were generally higher during October to December. Residues of DDT were higher at Moti Nagar which is near a DDT factory. Residues of HCH were maximum at Town Hall, a commercial area of the city.     

DDT residues in the River Jamuna in Delhi,India

Water, Air, &; Soil Pollution - DDT residues in water, bottom sediments and certain non-target organisms from four different sites of the river Jamuna in Delhi were monitored periodically from...     

Liquid chromatographic determination of vitamin D in infant formula

A method is described for the determination of vitamins D2 + D3 in milk- and soy-based infant formula. Vitamins D2 and D3 are extracted from the saponified sample and converted to isotachysterols with acidified butanol. Reverse-phase liquid chromatography (LC) is used to remove interferences, and total vitamin D is quantitated using normal-phase LC. Recoveries of spiked samples averaged 97.6% for milk-based infant formula, and 98.8% for soy-based infant formula. This method quantitates vitamin D2 + D3 in infant formulas containing as low as 40 IU/qt when prepared according to label direction.     

Empirical Explorations of SYNCHEM

During the past several years, a substantial body of experience has accumulated in the use of SYNCHEM, a large-scale program which is able to discover synthesis routes for relatively complex organic structures without on-line guidance on the part of its chemist user. These results indicate that the approach to computer-directed organic synthesis route discovery embodied in the program has been valid and reasonable, and that SYNCHEM is likely to be fruitful from the point of view of its intended users as well as for our research objectives in artificial intelligence. The experiments have revealed a number of insufficiencies in the program as well. Most of these are rectified in SYNCHEM2, a revised version of the program which includes, among other improvements, a more highly developed synthesis search algorithm and the routine consideration of stereochemistry.     

Inactivation of TNF signaling by rationally designed dominant-negative TNF variants

Tumor necrosis factor (TNF) is a key regulator of inflammatory responses and has been implicated in many pathological conditions. We used structure-based design to engineer variant TNF proteins that rapidly form heterotrimers with native TNF to give complexes that neither bind to nor stimulate signaling through TNF receptors. Thus, TNF is inactivated by sequestration. Dominant-negative TNFs represent a possible approach to anti-inflammatory biotherapeutics, and experiments in animal models show that the strategy can attenuate TNF-mediated pathology. Similar rational design could be used to engineer inhibitors of additional TNF superfamily cytokines as well as other multimeric ligands.