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Abstract  

The potentiometric determination of uranium is widely carried out in phosphoric acid medium to suppress the interferences of plutonium by complexation. Owing to the complexity of the recycling plutonium from the phosphate based waste involving manifold stages of separation, a method has been proposed in the present paper which does not use phosphoric acid. Uranium and plutonium are reduced to U/IV/ and Pu/III/ in 1M H2SO4 by Ti/III/, and NaNO2 is chosen to selectively oxidize Pu/III/ and the excess of Ti/III/. The unreacted NaNO2 is destroyed by sulphamic acid and excess Fe/III/ is added following dilution. The equivalent amount of Fe/II/ thus liberated is titrated against standard K2Cr2O7. R.S.D. obtained for the determination of uranium /1–2 mg/ is 0.3% with plutonium being present upto 4.0 mg.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: S. Balasubrahmanyam, B. Viswanathan, V. Rao, and J. Kuriacose

Abstract  

The effect of60Co -radiation on La2CuO4 solid catalyst prepared by the ceramic method has been studied. Gamma irradiation of La2CuO4 samples has been found to increase the Cu+ content, electrical conductivities and decrease the magnetic susceptibilities of the catalyst. The results have been interpreted on the basis of the crystal field model of the structure of La2CuO4.

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Some studies on thallium oxalates — IV

Thermal decomposition of rubidiumbis-oxalato diaquo thallate(III) dihydrate

Journal of Thermal Analysis and Calorimetry
Authors: S. R. Sagi, Karri V. Ramana, and M. S. Prasada Rao

Thallium(III) was precipitated with oxalic acid in the presence of 0.025M RbNO3 (or 0.0125M Rb2SO4) in 0.1M HNO3 (or 0.05M H2SO4). Chemical analysis of the solid obtained corresponds to the formula Rb[TlIII(C2O4)2]·4 H2O. Thermal studies (TG, DTG and DTA) indicated the dehydration and redox decomposition of the thallic salt to the thallous salt, and finally to a mixture of rubidium carbonate and oxides of thallium(I) and thallium(III). Infrared absorption spectra, microscopic observations and X-ray diffraction data were used to characterize the original salt, as well as the intermediates formed during the thermal decomposition of the salt. On the basis of these results, the salt may be represented as: Rb[TlIII(C2O4)2(H2O)2]·2 H2O.

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Ten dicoccum wheats were analyzed for their physico-biochemical and milling properties to evaluate the pasta making potential. Dicoccums showed higher protein content and mixograph midline peak values compared to durum variety MACS2846. Mixographic properties of dicoccums were poor compared to durums, due to lower functional visco elastic gluten content. Dicoccums were poorer in milling properties compared to durums, due to lower test weight and thousand-grain weight. Among dicoccums, DDK 1025 showed high micro SDS sedimentation volume and strong mixographic properties, but values were still lesser compared to durum MACS 2846. HMW glutenin subunits in recently developed/released dicoccums were similar to durum parents and were different from the older dicoccums. LMW glutenin subunits, however, were similar to dicoccum parents, except in DDK 1025 which showed LMW glutenin subunits similar to durum wheat. To breed high quality dicoccum wheat for pasta products, breeders should select superior glutenin subunits composition, along with better mixograph properties, keeping morpho-botanical characteristics of dicoccum wheat.

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A novel, rapid, and sensitive liquid chromatography-tandem mass spectrometric method was developed and validated for the simultaneous quantification of tenofovir, emtricitabine, and efavirenz in human plasma. Nevirapine was used as an internal standard. The analytes and the internal standard were extracted from human plasma sample by solid-phase extraction technique (SPE). The reconstituted samples were chromatographed on a Chromolith ROD C18 column (50 × 4.6 mm; 5 μ) by gradient elution using a mixture of ammonium acetate buffer (5 mM) and 0.1% formic acid in acetonitrile as the mobile phase at a flow rate of 1.0 mL min−1. The calibration curve obtained was linear (r 2 ≥ 0.9990) over the concentration range of 2.5–650 ng mL−1 for tenofovir and 10–4000 ng mL−1 for emtricitabine and efavirenz. The results of the intra- and inter-day precision and accuracy studies were well within the acceptable limits. A run time of 2.5 min for each sample made it possible to analyze more than 300 plasma samples per day. The proposed method was found to be applicable to clinical studies, and the authenticity in the measurement of clinical data is demonstrated through incurred samples reanalysis (ISR).

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Sorghum can be an alternative to corn for industrial uses, especially in drought prone areas of the world. Sorghum cultivars with high potential of grain and starch yields are needed to continuously meet the industrial demands. We have studied the genetics of grain yield and starch content of sorghum to decide the breeding procedure to develop suitable cultivars for starch industry. The genetic material from 8 × 8 diallel (28 F1 and 8 parents) was grown in a randomized complete block design, with three replications at Directorate of Sorghum Research, Hyderabad, India. Observations were recorded on seven agro-morphological and two grain quality traits including grain yield and starch content. Correlation studies revealed that the grain hardness was negatively correlated to starch and positively correlated to grain yield, panicle weight and days to flowering. Variance due to specific combining ability effects was greater in magnitude for both starch content and grain yield. Bi-parental crossing in F2 will help in getting pure lines with high starch content and high grain yield. The parents chosen for breeding program need to be good combiners for starch and grain yields to obtain superior hybrid. One MS line, 422B was a good combiner for grain yield, high starch content and 100 grain weight, and had good per se performance.

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The high temperature superconducting compound YBa2Cu3O72212;δ (Y-123) is synthesised by sol-gel process using various precursors viz., acetate, acetate-citrate, nitrate-citrate and acrylamide. The phase purity of the final product depends on the homogeneity of the gels which intern depends on the bonding of the metal ions in the gels. The samples prepared by acrylamide and nitrate-citrate gel routes yielded phase pure Y-123 compound with better superconducting properties. The mechanism of formation of Y-123 in all these four gel routes is established by characterising the gels and intermediate phases using TG, DTA and XRD techniques. Kinetic analysis is carried out on the mass loss data using the method proposed by Phadni's and Deshpande. Avrami-Erofeev nuclei growth in case of acrylamide, diffusion controlled process in nitrate-citrate and phase boundary reaction mechanisms in case of acetate-citrate gels are found to be responsible for the formation of Y-123 phase.

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Summary  

A recent study has indicated the feasibility of recycling of chemicals from alkaline waste generated in the preparation of UO3 microspheres by the internal gelation process. Present paper investigates the recycle process, the volume of the secondary uranium waste. Result shows that prior to start the recycle process, the waste solution should be freed from uranium by ion-exchange. Optimized experimental condition to achieve maximum reduction in the volume of uranium based waste is discussed.

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Abstract  

The Environmental Survey Laboratory is responsible for the monitoring of radioactivity due to natural and artificially produced radionuclides in a variety of samples available around the nuclear facilities at Tarapur. Standard methods of radiochemical separation and counting are followed to determine -emitters in various matrices. To make the measurement simple and detect lower levels of contamination in some of the matrices, a method was developed to measure the high energy gross -activity primarily due to 90Y in borehole water and urine samples of occupational workers by Cerenkov counting in a liquid scintillation analyser. Cerenkov counting results of borehole samples were compared with the total gross -activity measured by a low background beta-counter. The combined measurements were used to evaluate 90Sr and 137Cs levels without chemical separation or gamma-spectrometry. Cerenkov counting technique was also utilised to evaluate 40K in drinking water and intercomparison water samples. The paper presents the methodology and results of a few measurements using the technique.

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