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  • Author or Editor: M. Tariq x
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Abstract  

The use of L X-ray fluorescence for the determination of the concentration of Pb in human bone has been reported in the literature. A critique of the utility of the method and the shortcomings as an analytical approach in the evaluation of human exposure to Pb are addressed.

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Thermal decomposition of Fc4Sn3Br166H2O was investigated by thermogravimetry. The decomposition products were characterized by U.V.-Visible spectroscopy, chemical analysis and X-ray diffraction. The TG curve of the complex showed three decomposition steps. In the first, a mixture of HBr and H2O was evolved. A ferricinium tin bromide compound (Fc4SnBr8) was found to sublime in the second step, whereas a mixture of HBr and H2O was given off in the third, leaving SnO2 as the residue, The stoichiometry of the thermal decomposition of [Fc4Sn3Br16 6H2O] has been established and a possible mechanism for its decomposition is suggested.

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Bacillus thuringiensis (B.t) is well known for its biocontrol potential against a variety of insects. Nematicidal potential of ten B.t isolates was tested against root-knot nematodes (Meloidogyne javanica (Treub) Chitwood) in vitro, under greenhouse as well as in field conditions. Eggs and second stage juveniles (J2) were exposed to 5 and 25% concentrations of bacterial cell-free aqueous extracts up to 96 h. B.t isolates showed lesser degrees of nematicidal activity at 5% concentration. However, some B.t isolates (B.t-14, B.t-16 and B.t-64) greatly reduced egg hatching and increased J2. All B.t isolates revealed suppressed egg hatching and increased mortality of J2 at 25% concentration. Soil applications with most of the B.t isolates under greenhouse and field conditions significantly improved height and fresh weights of root-knot nematode parasitized okra (Abelmoschus esculentus (L.) Moench). Some isolates, including B.t-64 reduced the number of galls and egg masses. B.t-64 reduced gall formation up to 70% under greenhouse conditions. However, 29% of decrease was observed in field conditions. Similarly, B.t-64 treated plants showed a 56% decreased in eggs/egg mass in a field experiment. Population of root-knot nematodes in the rhizosphere was decreased up to 61% in the field experiment as compared to control.

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