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  • Author or Editor: M. Iqbal x
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Abstract  

The determination of Ce, Yb, Se and Cr has been carried out in the atmosphere of Lahore, Faisalabad, Rawalpindi, Islamabad, Wah Cantt and Khanispur (background area) by INAA. Ce and Cr are associated with anthropogenic activities, while Yb is mainly due to soil derived aerosols. Se represents both anthropogenic as well as soil derived aerosols.

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Abstract  

Industrial units play a significant role in atmospheric pollution. Industrial exhausts deteriorate the atmospheric quality causing unhygienic environment for the people working in the vicinity. This work presents a study of the longitudinal distribution of trace elements of the Sheikhupura industrial area. Three kinds of distribution patterns were observed and are discussed in detail. The results are based on the neutron activation analysis of 16 trace elements.

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Abstract  

New Schiff bases, salicylidene- and pyridoxylidene-thyroxine have been prepared and characterized. They were labeled with99mTc. The labeling yield of the Schiff bases was over 95%. About 60% of the activity was bound to -globulin and albumin fractions when the labled compounds were incubated with a serum sample. The labeled compounds, after i.v. administration to rats, rapidly cleared from blood and excreted into the small intestine. They appeared to behave as hepatobiliary agents.

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The effects of aluminium on seed germination, shoot, root and dry weight of two wheat cultivars were studied. The seed germination of Triticum aestivum cv. 'Faisalabad 85' and Triticum aestivum cv. 'Blue Silver' was significantly (p < 0.05) affected by different concentration of aluminium as compared to the control. The increase in concentration of aluminium at 10 ppm suppressed the root and shoot length in T. aestivum cv. 'Faisalabad 85', whereas the reduction in shoot length was observed for T. aestivum cv. 'Blue Silver' at 15 ppm. A significant (p < 0.05) reduction in dry weight of 'Blue Silver' was observed at 25 ppm aluminium.

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Abstract  

Extraction of Pr(III), Ho(III) and Er(III) has been studied in the pH range of 1–10 with N-benzoyl-N-phenylhydroxylamine (BPHA) in benzene. The separation was found to be quantitative in borate media from pH 7 to 10, at an ionic strength of 0.1M (H+, BO3 3–). The stoichiometric composition of the complexes under the optimal conditions of shaking time, pH and reagent concentration was formulated using slope analysis and found to be M(BPHA)3, where M=Pr(III), Ho(III) and Er(III). The effect of various masking agents shows that citrate, ascorbate, EDTA, oxalate, fluoride and phosphate form stable complexes with these rare earths as compared to BPHA. The decontamination factors for different cations with respect to these rare earths under the optimum conditions have been evaluated.

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Abstract  

Superoxide dismutase, containing copper and zinc, has been labeled with copper-64 by incubating the prepared apoenzyme with cupric(65) chloride at room temperature. No significant loss in the enzymatic activity was observed after labeling. The incorporation of copper-64 was ascertained by starch gel electrophoresis and high performance liquid chromatography. The labeling efficiency was found to be >95%.

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Detection of genotypic variation in response to water stress at seedling stage could help in escalating selection intensity in breeding drought tolerant varities. Nine genotypes were tested for seedling survivability under drought stress. Four genotypes, i.e. ‘Sarsabz’, ‘Sitta’, ‘Fareed’ and ‘FD-83’, showed complete survival on resumption of irrigation after drought stress. These genotypes were late dying as they withered slowly under drought. Percent wilting and percent survival on resumption of irrigation were negatively correlated. Six genotypes were selected on the basis of seedling survivability (late and early dying) and evaluated for seedling growth response under drought. Root length and dry weight increased significantly under stress in ‘Sitta’, ‘FD-83’ and ‘Fareed’. Drought stress also increased the root-to-shoot length ratio in ‘FD-83’ and ‘Fareed’. However, seedling fresh and dry weight significantly reduced in ‘Nesser’ and ‘Inqalab-91’ under stress. In ‘FD-83’, seedling fresh and dry weight increased over control under stress. Results indicated that seedling survivability, root-to-shoot length ratio, root length and dry weight were most important traits for screening drought tolerance at seedling stage. On the basis of these indices, ‘Sitta’, ‘Fareed’ and ‘FD-83’ were classified as drought tolerant, ‘Sarsabz’ and ‘Nesser’ as moderately tolerant and ‘Inqalab-91’ as sensitive genotypes. Collectively, results suggested that selection by combining seedling survivability, growth response, RWC and leaf water potential can be efficiently used for rapid evaluation of drought tolerance in wheat breeding.

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Abstract  

Thermal degradation of copolymers, prepared from glycidyl methacrylate and acrylonitrile in varying molar ratios using 2,2′-azobisisobutyronitrile as an initiator, was studied by thermogravimetry, derivative thermogravimetry, differential thermal analysis and mass spectrometry. The fragmentation patterns in the mass-spectra were interpretable by comparison with the known degradation patterns of the related materials. Thermal kinetic parameters, including activation energies and order of reaction of the degradation of the prepared copolymers, were calculated from their thermoanalytical data. These parameters suggest an overall increase in thermal stability with increasing content of acrylonitrile in the copolymers.

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Abstract  

Diphenyl-2-pyridylmethane, a high molecular weight substituted pyridine has been examined and found to be a useful solvent extraction reagent. Its behaviour is similar to amines in that it forms salts with mineral acids. The acid ionization constant (pKBH +) determined spectrophotometrically has a value of 4.41±0.06 at 25 °C. A study of the partition behaviour of trace amounts of gold between mineral acid solutions and 0.1M diphenyl-2-pyridylmethane dissolved in chloroform indicates that the metal can be quantitatively extracted from dilute mineral acid solutions and also from concentrated hydrochloric acid media in a single extraction. Attempts have been made to gain an understanding of factors affecting the extraction of gold. Common anions have little effect on extraction in concentrations upto 1M. Separation factors of a number of metal ions relative to gold are reported for three mineral acid systems; and gold has been estimated in some synthetic samples using neutron activation technique by prior extraction with 0.1M solution of diphenyl-2-pyridylmethane dissolved in chloroform.

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