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  • Author or Editor: S. Srivastava x
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Abstract  

Preliminary results are described of a123Xe filled device to serve as a combination123I generator/iodination kit.123X was produced in the Brookhaven Linac Isotope Producer (BLIP) by the reaction127I(p, 5n)123Xe. The device consists of a small glass ampoule containing an internal glass breakseal and a flanged neck on which was crimped a multi-injection type septum. The ampoule contained a hydrogen sulfide atmosphere to assure that the iodine generated from the decay of the xenon was in the form of iodide. Following an adequate period for123Xe to decay (this period can be used for shipment), a needle is forced through the septum breaking the seal and residual gases are pumped off. The123I in the form of iodide can then be rinsed from the ampoule with any desired solvent or reagent added directly to the device to carry out an iodination in an enclosed environment. Preliminary results of both iodine recovery and iodinations have been promising.

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Abstract  

Sorption of some univalent, divalent and trivalent metal ions has been studied on the hydrogen form of titanium arsenate and titanium tungstoarsenate gels as a function of initial solution concentration at pH 5–6. The effect of pH on maximum uptake (Qmax) has also been seen for some representative ions. Sorption of metal ion becomes almost negligible below pH 1.8, with the exception of monovalent cations. Rubidium ions exhibit interesting adsorption behaviour. The data have been compared with the exchange properties of these two inorganic ion exchangers, as reported earlier6,8.

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Abstract  

A simple, rapid and inexpensive ascending thin-layer and paper radiochromatographic procedure is described, which can be used in the separation and possible identification of some99Mo(V) and99Mo(VI) polyaminocarboxylic acid chelates.

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Commelina benghalensis (Commelinaceae) is widely used as traditional and folklore medicine in India. In the present study, a reverse-phase high-performance liquid chromatography—photodiode array detection (RP-HPLC—PDA) method was developed for the separation, identification, and quantification of bioactive phenolics. Antioxidant potential was also accessed to validate the presence of identified markers. Method was developed on C18 column with 1% formic acid (in water) and acetonitrile as solvent system, and data acquisitions were achieved at wavelength of 285 nm. The developed method was also validated for accuracy, precision, robustness, limit of detection and quantification (LOD and LOQ), repeatability, and recovery according to International Conference on Harmonization (ICH) guidelines. In this method, five phenolics, viz., protocatechuic acid (0.033%), vanillic acid (0.262%), ferulic acid (0.365%), apigenin (0.126%), and kaempferol (0.544%), were quantified in linearity range of 0.2–1.0 μg with correlation coefficient of more than 0.9949. Relative standard deviation (RSD) (%), LOD, LOQ, and recovery (%) are within the acceptable limit. Besides that, methanolic extract shows the inhibition (%) range from 24.45 to 68.75% at 0.02–0.12 mg mL−1. IC50 of extract was observed at 46.75 μg mL−1, suggesting the promising activity in methanol extract. Hence, the proposed method for simultaneous quantification of five bioactive phenolics in the tuber of C. benghalensis using HPLC–PDA detection under the specified conditions is specific and accurate, and validation proves its selectivity and reproducibility.

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Abstract  

Copolymers of vinyl acetate and ethylene were prepared by emulsion polymerization using ammonium persulphate and sodium metabisulphite as initiators in presence of cyclohexane. Several copolymer samples were prepared by changing initial pressure of ethylene from 100 to 250 psi. The copolymer composition was determined by 1H-NMR and thermogravimetric analysis in nitrogen atmosphere.

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Thermal and infrared spectral studies of the urea-orthoboric acid complex are reported. The complex is formed through the elimination of 0.5 H2O molecule. Infrared spectral data show the presence of hydrogen-bonding and the force constant calculated for the N ... HO bond is found to be 4−5×10−5 dyne cm−1, which is for the order of a single bond and indicates strong hydrogen-bonding in the complex. A tentative structure for the complex is proposed.

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Abstract

The kinetics of the decolorization reactions of triphenylmethane dyes (BG, MG and PRH) with the cyanide ion (nucleophile) were studied in the presence of anionic micelles of sodium dodecyl sulfate (SDS). The reactions follow pseudo-first order kinetics. The rate constant depends on surfactant concentration. SDS micelles inhibit the overall rate of the reaction between the dye carbocation with the nucleophile. Quantitative analysis of the micellar data obtained has been done by applying a positive cooperativity model of enzyme catalysis. For all the dyes under study, the value of n (index of cooperativity) has been found to be greater than one. The inhibitory effect has been explained in terms of hydrophobic and electrostatic interactions of various species present in the reaction systems.

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Abstract  

Ion-exchange papers were prepared by impregnating chromatographic Whatman No. 3 paper with pyridinium tungstoarsenate exchanger. The composition of the material loaded on the paper shows that the compound has the formula (C5H5NH)3 W1 2AsO4 0·Rf values of 30 metal ions were determined on these ion-exchange papers by developing with ascending technique in solvents containing mixtures of n-propanol and hydrochloric or nitric acid. Several binary, ternary and some quaternary separations were also achieved on these papers. Studies were also made on plain papers for comparison.

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Abstract  

The uptake and release kinetics of134Cs by Goldfish (Carassius auratus) and137Cs by Zebra Fish (Brachydanio rerio) from aquatic media of different ionic compositions and temperature was studied in controlled laboratory conditions. The accumulation of radiocesium in the case ofBrachydanio rerio is observed to be strongly dependent on the potassium ion concentration of the aquatic medium, but in the case ofCarassius auratus this dependence is quite weak. The biological half-lives of the cesium isotopes incorporated into the fish investigated in the present work vary from 19 to 80 days and are influenced by the temperature and the ionic composition of the aquatic medium.

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