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  • Author or Editor: T. Kumar x
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Abstract  

The thermal decomposition of unirradiated and -irradiated lead nitrate was studied by the gas evolution method. The decomposition proceeds through initial gas evolution, a short induction period, an acceleratory stage and a decay stage. The acceleratory and decay stages follow the Avrami-Erofeyev equation. Irradiation enhances the decomposition but does not affect the shape of the decomposition curve.

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A simple, precise, accurate, and rapid HPTLC method for quantitative analysis of venlafaxine hydrochloride in the tablet dosage form has been established and validated. Chromatographic separation was performed on 10 cm × 20 cm aluminum backed HPTLC plates coated with 0.2-mm layers of silica gel 60 F254, previously washed with methanol, with toluene-methanol 7:3.5 (v/v) as mobile phase. Densitometric evaluation was performed at 228 nm. Experimental conditions, for example size of band applied, chamber saturation time, solvent front migration, slit width, etc., were critically studied and the optimum conditions determined. The drug was satisfactorily resolved at R F 0.19. The validated calibration range was 400–2000 ng per band (r = 0.999). The suitability of the method for quantitative analysis of the compound was proved by validation in accordance with the requirements of pharmaceutical regulatory standards. The selectivity, accuracy, precision, and speed of the method make it useful for routine analysis of the pharmaceutical preparation in industrial quality-control and regulatory laboratories.

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Abstract  

Soil samples collected at the Indian Antarctic station Maitree, situated at the Schirmachar Oasis and belonging to the East Antarctic charnockite provinces have been analysed to determine trace uranium concentrations. The fission track technique using Makrofol-KG as the track detector was used for the analyses. Finely powdered samples and pellets were irradiated with thermal neutrons from a nuclear reactor. Uranium concentrations were obtained from the tracks of the detector. Uranium concentrations were found to vary from 0.036 to 0.364 ppm in the samples investigated. The low levels of uranium indicate the absence of human intervention with the lithosphere in this region.

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Abstract  

Plutonium and uranium was extracted from nitric acid into trioctyl phosphine oxide in xylene. The TOPO layer was analysed by spectrophotometry. Thoron was used as the chromogenic agent for plutonium. Pyridyl azoresorcinol was used as chromogenic agent for uranium. The molar absorption coefficient for uranium and plutonium was found to be 19000 and 19264 liter/mole-cm, respectively. The correlation coefficient for plutonium and uranium was found to be 0.9994. The relative standard deviation for the determination of plutonium and uranium was found to be 0.96% and 1.4%, respectively.

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Abstract  

During nuclear fuel reprocessing, monitoring of U and Pu concentration in every stage is very essential for process control purpose. A simple and fast spectrophotometric method for a simultaneous estimation of U and Pu in Plutonium Uranium Recovery by Extraction (PUREX) process’s tail end stream like Pu product where Pu concentration is much richer than that of U is described here. The method involves reduction of the bulk amount of Pu to Pu(III) using ascorbic acid in 1 M HNO3. Visible absorption peaks were measured at 416 nm for U and at 600 nm for Pu using a fiber optic probe of path length 40 mm. The methodology enables quantification of U and Pu concentration in the Pu product samples with a precision of 2.8 and 2.1%, respectively.

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Abstract  

To achieve end user’s specified PuO2, controlling and monitoring of Pu in its fourth valency state is essential prior to the conversion of Pu-nitrate to its oxide through oxalate precipitation process. Conventional radiometric procedure for the analysis of Pu oxidation state in Pu-nitrate solution containing trace level of Pu(III) has limitation due to oxidation of Pu(III) during the sample preparation with respect to acidity. A simple direct spectrophotometry using an optic fiber spectrophotometer was attempted for the estimation of trace level of Pu(III), after separating the bulk amount of Pu(IV) by maintaining the sample acidity. By using a synergistic mixture of 30 % TBP and 1 M theonyl trifluoro acetone in benzene, the Pu(IV) could be removed to a level which doesn’t interfere in the Pu(III) absorption.

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Abstract  

Thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) investigations were carried out on gamma irradiated SrBPO5 samples doped with CeO2 and co-doped with CeO2 and Sm2O3. On gamma-irradiation at room temperature, BO3 2–, O2 and O radicals were produced. It was seen that the O radical ion disappeared in the sample annealed at 500 K. It is proposed that the recombination between trapped electrons and O radical ions results in transfer of recombination energy to the impurity centre Ce3+ resulting in TSL glow peak at 485 K. In the case of co-doped samples energy transfer occurs between Ce3+ to Sm3+ resulting in increase in the intensity of glow peak at 485 K.

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Prolonged (120 days) oral administration of a beta adrenoceptor agonist, isoproterenol hydrochloride (dose = 1.5 mg/kg body weight) resulted in an increase in the live weight of growing chicks (Gallus domesticus). Measurement of dry muscle mass and total proteins in muscle homogenates from M. pectoralis major, M. pectoralis minor suggested a muscle hypertrophy largely responsible for this live weight increase. Further, an increase in organ weight and total tissue proteins supported cardiac hypertrophy in chicks as a result of isoproterenol administration. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) revealed alterations in actin myosin profiles implying a drug induced change in phenotypic expression of myofibrillar component of both skeletal and cardiac muscle. The results suggest that prolonged treatment of chicks produced changes that were not much different from those recorded immediately within a fortnight.

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Four species of Lejeunea viz., L. discreta, L. kashyapii, L. mehrana and L. parva are reported here for the first time from Meghalaya. Of which, Lejeunea kashyapii and L. mehrana are endemic, earlier reported from Sikkim only. The taxonomic description and illustrations of all are provided in present communication.

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Summary

Root exudates were obtained from three mangrove species, viz. Bruguiera gymnorrhiza, Excoecaria agallocha, and Heritiera fomes. Spot tests revealed the presence of, presumably, phenolic compounds in the exudates. Paper chromatography revealed two spots each for B. gymnorrhiza and H. fomes and a single spot for E. agallocha. GC-MS analysis suggested the presence of aminopyrine, palmitic acid, stearic acid, di-n-propyl ether, and 2,5-anhydrogluconic acid in B. gymnorrhiza exudates, aminopyrine and palmitic acid in E. agallocha exudates, and aminopyrine, palmitic acid, and 2,5-anhydrogluconic acid in H. fomes exudates.

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