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  • Author or Editor: B. Purkayastha x
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Abstract  

The study of the Nicotiana rustica variety from North Bengal, revealed that the respective amounts of radioactive nuclei40K,90Sr,90Y and rare earth activity as well as210Pb were found to be 4.04, 2.42, 4.52, and 0.052 pCi/g of cured leaves. In another investigation with Nicotiana tabaccum variety from Rajahmundri, Andhra Pradesh, contents of40K,90Sr,90Y and rare earth activity, and210Pb were observed to be 4.06, 1.02, 3.44 and 0.20 pCi/g of cured leaves, respectively. Results indicate that the amount of polonium which is presumably in equilibrium with RaD in these two varieties of Indian tobacco leaves is very small. Detailed studies on different varieties of Indian tobacco are in progress.

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Abstract  

The study of homogeneous distribution coefficients in determining the transition temperatures of isomorphologically analogous components and in predicting the existences of some new unstable compounds has been carried out in detail with special references to vitriols of nickel, manganese, zinc, copper and magnesium. In the course of the investigation with NiSO4·7H2O as host and54Mn as guest, the transition temperature of orthorhombic NiSO4·7H2O was shown to be 26.5 °C, and with orthorhombic ZnSO4·7H2O and MgSO4·7H2O as host and copper sulphate as guest, the limits of existences of orthorhombic CuSO4·7H2O and newly predicted CuSO4·6H2O were found to be 13.5° to 44 °C and 44° to 51 °C, respectively. In addition, the transition temperatures of orthorhombic MnSO4·7H2O (10 °C), stable NiSO4·7H2O (30.5±5 °C) and orthorhombic ZnSO4·7H2O (39 °C) were verified. The new method of approach is very simple, reproducible and easily adaptable.

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Abstract  

The separation of zirconium and hafnium by fractional precipitation as pyrophosphate1 has been extended for the preparation of pure hafnium. The favourable uptake of hafnium, in spite of the decreasing tendency of partition factor when hafnium concentration is high, is maintained for all concentration of hafnium (relative to zirconium). Particularly significant is the fact that at very high concentrations of hafnium (at≈84%) the uptake of zirconium sharply falls. So pure hafnium can be prepared from natural zirconium by a simple process of eight or nine stages of fractional precipitations as pyrophosphate. This process yields reactor grade zirconium on the one side and pure hafnium on the other side.

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Abstract  

A heterogeneous distribution study with internally formed lead chromate as host and110Ag as guest indicates the existence of a new variety of lead chromate, which forms mixed crystals with silver chromate, and differs in morphology from the aged variety. It is inferred that the formation of mixed crystals is probably due to breeding of a morphologically analogous and unstable species by the guest component. By means of study of the homogeneous distribution coefficient, D, of the system consisting of KFe(SO4)2·12H2O as host and110Ag as guest, the existence of an unknown alum, AgFe(SO4)2·12H2O, in trace amounts has been demonstrated. A distribution study of the system shows that KFe(SO4)2·12H2O forms mixed crystals with110Ag up to 10°C, after which the uptake follows an adsorption pattern. The transition temperature of the guest alum, indicated by a sharp change in the D values, is found to be 10°C. Application of radioactive tracers in the study of new and unstable compounds have been stressed.

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Abstract  

The method of determining the homogeneous distribution coefficient by the partial crystallization procedure has been examined. It has been found that in chemically very similar systems, such as FeSO4·7H2O as host and60Co as guest, the partial crystallization technique gives very reliable data. However, in the case of CoSO4·7H2O as host and copper tracer as guest, the distribution coefficient found by the partial crystallization procedure is much lower than that obtained by the traditional method of complete equilibration. In this system the distribution coefficient increases as the period of partial crystallization is lengthened. The probable explanation of this particular behaviour is discussed.

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Abstract  

Co-separation of hafnium with zirconium oxychloride has been studied from 0 to 60°C with the help of175,181Hf. It was found that zirconium oxychloride undergoes two transitions, one at about 33°C and another at about 59.5°C. From the value of the partition factor it was clear that a separation method based on fractional crystallisation of the oxychloride will not be a successful line of approach. The transition points were verified by DTA study. It was found from the DTA curve that hafnium oxychloride undergoes transition near 90°C. The solubility of zirconium oxychloride and the break in the partition factor also corroborate the above findings.

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Acta Alimentaria
Authors:
D. Das
,
S. Tamuly
,
M. Das Purkayastha
,
B. Dutta
,
C. Barman
,
D.J. Kalita
,
R. Boro
, and
S. Agarwal

Abstract

Green tea or its concentrated extract is coveted for its health promoting catechin-like polyphenols, especially epigallocatechin-3-gallate (EGCG). However, its amicable efficacy is now being doubted considering the recent occurrence of several cases of hepato- and nephrotoxicity, after the ingestion of EGCG-fortified (≥85–90%) nutritional supplements. Therefore, the current study was carried out to ascertain the effect of green tea leaves extract (GTE), having low EGCG content (73.8%), on liver and kidney functions of male Wistar rats using various in vivo experiments and in vitro radical scavenging activity. In terms of acute toxicity, GTE was observed to be safe when delivered at a dosage of 2000 mg kg−1 body weight (BW). Oral delivery of GTE for 28 days at a concentration of 200 mg kg−1 BW/day did not trigger sub-acute toxicity to the liver and kidneys, as per serum biochemical analyses and histopathological examination. In contrast, GTE counteracted the effects of carbon tetrachloride (a potent hepato-degenerative compound) on the liver. Furthermore, increase in high-density lipoprotein―cholesterol with concomitant lowering of serum triglycerides and low-density lipoprotein―cholesterol were noticed in GTE-treated rats. These findings suggest that low EGCG containing GTE, with appreciable antioxidant activity (IC50 = 53.18–71.28 μg mL−1), can serve as a hepatoprotective, hypolipidemic, and hypocholesterolemic ingredient.

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