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Abstract  

Bioassay technique is used for the estimation of actinides present in the body based on their excretion rate through body fluids. For occupational radiation workers urine assay is the preferred method for monitoring of chronic internal exposure. Determination of low concentrations of actinides such as plutonium, americium and uranium at low level of mBq in urine by alpha spectrometry requires pre-concentration of large volumes of urine. This article deals with standardization of analytical method for the determination of 241Am isotope in urine samples using Extraction Chromatography (EC) and 243Am tracer for radiochemical recovery. The method involves oxidation of urine followed by co-precipitation of americium along with calcium phosphate. This precipitate after treatment is further subjected to calcium oxalate co-precipitation. Separation of Am was carried out by EC column prepared by PC88-A (2-ethyl hexyl phosphonic acid 2-ethyl hexyl monoester) adsorbed on microporous resin XAD-7 (PC88A-XAD7). Am-fraction was electro-deposited and activity estimated using tracer recovery by alpha spectrometer. Ten routine urine samples of radiation workers were analyzed and consistent radiochemical recovery was obtained in the range 44–60% with a mean and standard deviation of 51 and 4.7% respectively.

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Abstract  

A preconcentration neutron activation analysis (PNAA) method involving reversed-phase extraction chromatography on 8-hydroxyquinoline-loaded Amberlite XAD-2 resin has been developed for the simultaneous determination of selected trace elements in acid rain and natural water samples. Quantitative retention has been achieved for Co, Cu, Hg, V and Zn at pH 6.0 and for Cd at pH 7.0. Various factors that can influence the preconcentration procedure have been studied in detail. Concentrations of the elements have been determined by the direct irradiation of the resin without eluting them from the column. Both precision and accuracy of the PNAA method are very good. The detection limits vary between 0.01 and 3 ppb.

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Abstract  

Bioassay technique is used for the estimation of actinides present in the body based on their excretion rate through body fluids. For occupational radiation workers urine assay is the preferred method for monitoring of chronic internal exposure. Determination of low concentrations of actinides such as plutonium, americium and uranium at low level of mBq in urine by alpha spectrometry requires pre-concentration of large volumes of urine. This paper deals with standardization of analytical method for the determination of Pu-isotopes in urine samples using anion exchange resin and 236Pu tracer for radiochemical recovery. The method involves oxidation of urine followed by co-precipitation of plutonium along with calcium phosphate. Separation of Pu was carried out by Amberlite, IRA-400, anion exchange resin. Pu-fraction was electrodeposited and activity estimated using tracer recovery by alpha spectrometer. Twenty routine urine samples of radiation workers were analyzed and consistent radiochemical tracer recovery was obtained in the range 74–96% with a mean and standard deviation of 85 and 6% respectively.

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Abstract  

Bioassay technique is used for the estimation of actinides present in the body based on the excretion rate of body fluids. For occupational radiation workers urine assay is the preferred method for monitoring of chronic internal exposure. Determination of low concentrations of actinides such as plutonium, americium and uranium at low level of mBq in urine by alpha-spectrometry requires pre-concentration of large volumes of urine. This paper deals with standardization of analytical method for the determination of U-isotopes in urine samples using anion-exchange resin and 232U tracer for radiochemical recovery. The method involves oxidation of urine followed by co-precipitation of uranium along with calcium phosphate. Separation of U was carried out by Amberlite, IRA-400, anion-exchange resin. U-fraction was electrodeposited and activity estimated using tracer recovery by alpha-spectrometer. Eight routine urine samples of radiation workers were analyzed and consistent radiochemical tracer recovery was obtained in the range of 51% to 67% with a mean and standard deviation of 60% and 5.4%, respectively.

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Abstract  

Studies on the individual potentiometric determination of uranium and plutonium in a single aliquot have been initiated recently in our laboratory. It was required to adapt the reported procedures (for the precise determination of uranium and plutonium individually when present together in a sample) at various stages to make them suitable for the successive application of the procedures to the same aliquot. Two alternative schemes are proposed in the present work. In the first, plutonium is determined by HClO4 oxidation followed by the determination of total uranium and plutonium by Zn(Hg) reduction. In the second, plutonium is determined by AgO oxidation following the determination of total uranium and plutonium by Zn(Hg) reduction. Amount of uranium is computed in both cases from the difference of two determinations. Precision for the assay of plutonium and uranium was found to be ±0.25% and ±0.35%, respectively, at milligram levels.

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Abstract  

Feasibility of using fixed bed column of conventional ion exchangers/sorbent and chemical precipitation based processes have been examined for the effective removal of the very low levels of 106Ru activity from NH4NO3 effluent generated during wet processing of rejected sintered depleted uranium fuel pellets. Based on the results, a simple process involving precipitation of cobalt sulphide along with ferric hydroxide was selected and further optimization of process variables was carried out. The optimized process has been found to be highly efficient in reducing 106Ru activity down to extremely low levels.

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Abstract  

A radiochemical displacement method was utilized for the determination of traces of mercury in water taking advantage of its ability to displace cobalt from cobalt(III) diethyldithiocarbamate tagged with60Co. The method is found to be applicable in the concentration range of 50–200 g/ml mercury. The interfernces from various cations like Fe(III), Co(II), Cu(II), Pb(II) and Ag(I) ions were studied.

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The present study was to investigate the effect of W. calendulacea on ischemia and reperfusion-induced cerebral injury. Cerebral ischemia was induced by occluding right and left common carotid arteries (global cerebral ischemia) for 30 min followed by reperfusion for 1 h and 4 h individually. Various biochemical alterations, produced subsequent to the application of bilateral carotid artery occlusion (BCAO) followed by reperfusion viz. increase in lipid peroxidation (LPO), hydrogen peroxide (H2O2), and decrease in reduced glutathione (GSH), catalase (CAT) and superoxide dismutase (SOD), level in the brain tissue, Western blot analysis (Cu-Zn-SOD and CAT) and assessment of cerebral infarct size were measured. All those enzymes are markedly reversed and restored to near normal level in the groups pretreated with W. calendulacea (250 and 500 mg/kg given orally in single and double dose/day for 10 days) in dose-dependent way. The effect of W. calendulacea had increased significantly the protein expression of copper/zinc superoxide dismutase (Cu-Zn-SOD) and CAT in cerebral ischemia. W. claendulacea was markedly decrease cerebral infarct damages but results are not statistically significant. It can be concluded that W. calendulacea possesses a neuroprotective activity against cerebral ischemia in rat.

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Journal of Thermal Analysis and Calorimetry
Authors:
K. Sreekanth
,
M. Kondaiah
,
D. Sravana Kumar
, and
D. Krishna Rao

Abstract

Ultrasonic velocity, u density, ρ and viscosity, η of mixtures of N,N-dimethyl acetamide with equimolar mixture of ethanol + isopropyl alcohol/isobutyl alcohol/isoamyl alcohol, including those of pure liquids over the entire composition have been measured at T = 308.15, 313.15, and 318.15 K. Using this data, various thermo-acoustic parameters such as deviations in ultrasonic velocity, Δu, isentropic compressibility, Δk s , viscosity, Δη, excess molar volume, and excess Gibb's free energy of activation for viscous flow, ΔG ∗E have been calculated at different temperatures. The calculated deviation and excess functions have been fitted to the Redlich–Kister type polynomial equation. The influence of temperature on the observed negative and positive values of deviation and excess thermodynamic properties has been explained in terms of molecular interactions present in the investigated acid–base liquid mixtures. The experimental data of ultrasonic velocity have been used to check the applicability of velocity models of Nomoto, Van Dael and Vangeel and Junjie and viscosity data have also been availed to test the applicability of standard viscosity models of Grunberg-Nissan, Hind-Mc Laughlin, and Katti-Chaudhary for all the systems investigated at various temperatures.

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Abstract  

Ten fresh water samples of wells and rivers from the environment of Tarapur Maharashtra Site were analyzed to evaluate and establish the fall out level of 137Cs activity concentration using large volume of water samples. A radiochemical separation method suitable for the analysis of large volume of water sample based on the adsorption of Cs isotopes on coated acrylic fibres was standardized. 134Cs isotope was used for monitoring the radiochemical recovery of the analysis. Radiochemical recovery was obtained in the range of 74–98% for a sample volume of 250 L or more. The fall out level 137Cs concentration in river/dam water was found to be in the range of 0.205 to 0.268 mBq L−1. The fall out level annual effective dose through water ingestion pathway for a member of public was evaluated to be 2.27 × 10−9 Sv.

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