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Abstract

Thermal decomposition of neat TBP, acid-solvates (TBP·1.1HNO3, TBP·2.4HNO3) (prepared by equilibrating neat TBP with 8 and 15.6 M nitric acid) with and without the presence of additives such as uranyl nitrate, sodium nitrate and sodium nitrite, mixtures of neat TBP and nitric acid of different acidities, 1.1 M TBP solutions in diluents such as n-dodecane (n-DD), n-octane and isooctane has been studied using an adiabatic calorimeter. Enthalpy change and the activation energy for the decomposition reaction derived from the calorimetric data wherever possible are reported in this article. Neat TBP was found to be stable up to 255 °C, whereas the acid-solvates TBP·1.1HNO3 and TBP·2.4HNO3 decomposed at 120 and 111 °C, respectively, with a decomposition enthalpy of −495.8 ± 10.9 and −1115.5 ± 8.2 kJ mol−1 of TBP. Activation energy and pre exponential factor derived from the calorimetric data for the decomposition of these acid-solvates were found be 108.8 ± 3.7, 103.5 ± 1.4 kJ mol−1 of TBP and 6.1 × 1010 and 5.6 × 109 S−1, respectively. The thermochemical parameters such as, the onset temperature, enthalpy of decomposition, activation energy and the pre-exponential factor were found to strongly depend on acid-solvate stoichiometry. Heat capacity (Cp), of neat TBP and the acid-solvates (TBP·1.1HNO3 and TBP·2.4HNO3) were measured at constant pressure using heat flux type differential scanning calorimeter (DSC) in the temperature range 32–67 °C. The values obtained at 32 °C for neat TBP, acid-solvates TBP·1.1HNO3 and TBP·2.4HNO3 are 1.8, 1.76 and 1.63 J g−1 K−1, respectively. Cp of neat TBP, 1.82 J g−1 K−1, was also measured at 27 °C using ‘hot disk’ method and was found to agree well with the values obtained by DSC method.

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Thermal stability and crystallization kinetics of Se–Te–Sn alloys using differential scanning calorimetry

DSC study of Se92Te8−x Sn x (x = 0, 1, 2, 3, 4, 5) chalcogenide glasses

Journal of Thermal Analysis and Calorimetry
Authors: Rajneesh Kumar, Pankaj Sharma, P. B. Barman, Vineet Sharma, S. C. Katyal and V. S. Rangra

Abstract

The present article deals with the differential scanning calorimetric (DSC) study of Se–Te glasses containing Sn. DSC runs are taken at four different heating rates (10, 15, 20 and 25 K min−1). The crystallization data are examined in terms of modified Kissinger, Matusita equations, Mahadevan method and Augis and Bennett approximation for the non-isothermal crystallization. The activation energy for crystallization (E c) is evaluated from the data obtained at different heating rates. Activation energy of glass transition is calculated by Kissinger's relation and Moynihan theory. The glass forming tendency is also calculated for each composition. The glass transition temperature and peak crystallization temperature increases with the increase in Sn % as well as with the heating rate.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: N. Khare, P. Govil, Pankaj Kumar, A. Mazumder, S. Chopra, J. Pattanaik, S. Balakrishnan and G. Roonwal

Abstract  

The variations in the concentration of 10Be in the core (SK 200/23) from south western Indian Ocean apparently illuminate past levels of 10Be. The level in the core where lower concentration of 10Be (1.01 × 109 atoms/g) is encountered during the Late Holocene is not at tandem with the Late Holocene southern hemisphere temperature variation. The results further suggest that during last glacial maxima (LGM) the 10Be concentration is higher (2.67 × 109 atoms/g) than the Late Holocene values. The present results, though preliminary, show that local bottom topography seems to have influenced the 10Be concentration at core site. Many studies from different geographic regions need to be undertaken before we finally consider 10Be as yet another strong proxy for palaeoclimatic reconstructions.

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Abstract  

During this work the determination of uranium in the range of μg·L−1 to tens of μg·L−1 was done by alpha-spectrometry after electroplating the aliquots of water sample using (NH4)2SO4 as an electrolyte. In general, the determination of uranium by alpha-spectrometry needs its separation from other transuranics specially thorium. The process described here does not involve any sample digestion and radiochemical separation of uranium from other transuranics. In this method an aliquot (1 to 3 mL) of the sample was dried and dissolve in (NH4)2SO4 and thereafter the sample was electroplated on a stainless steel (SS) planchet by using an electrochemical cell of special design. The proposed techniques have a distinct advantage over the determination of uranium by adsorptive stripping voltammetry (AdSV) in which uranium-chloranilic (2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone) acid complex was used for concentrating the uranium from the solution. Since in the case of AdSv, the determination of uranium was not possible for samples having dissolved organic carbon (DOC) more than 15 mg·L−1 and Cl concentration is in the range of 40,000 μ·g−1. In the case of spike experiments with 232U the recovery was observed in the range of 90–95% in aqueous medium having higher concentration of Cl and DOC as indicated above.

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Inorganic ion-exchangers in radioactive waste management

Part XVI: Uptake of some metal phosphates (stannic and zirconium) for 134Cs

Journal of Radioanalytical and Nuclear Chemistry
Authors: Shuddhodan P. Mishra, Diwakar Tiwari, Shailesh Kumar Prasad, R. S. Dubey and Manisha Mishra

Summary  

The uptake of indigenously synthesized amorphous stannic and zirconium phosphate was assessed for, one of the important fission fragment, cesium from aqueous solutions using a radiotracer technique. A virtual increase in sorptive concentration (from 1.0 . 10-8 to 1.0 . 10-2 mol . dm-3) and pH (from 2.4 to 10.2) and temperature (from 303 to 333 K) enhanced the uptake of cesium on stannic phosphate. However, the extremely high degree of uptake of cesium on zirconium phosphate was almost unaffected with the dilution beyond 10-5 mol . dm-3 and pH (i.e., from 2.4 to 10.2) and temperature (from 303 to 323 K). Irreversible uptake occurring for these solids follow the Freundlich adsorption isotherm and the presence of several complexing agents viz., sulphate, phosphate, glycine and EDTA did not affect appreciably the uptake of cesium on zirconium phosphate but it did affect for stannic phosphate system. Both these solids showed good radiation stability towards a 11.1 GBq Ra-Be neutron source having neutron flux ca. 3.2 . 106 n . cm-2 . s-1 and associated with a nominalg-dose of ca. 1.72 Gy/h, at least for the uptake of cesium.

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Nearly twenty thousand wheat lines were phenotyped for the presence of leaf tip necrosis (LTN), a phenotypic trait linked to adult plant leaf rust resistance (APR) genes, viz. Lr34, Lr46 and Lr67 having pleiotropic association with multiple disease resistance genes. Thirty-six lines showed varied expression of LTN and moderate level of leaf rust severity at adult plant stage with slow rusting (disease progress at a retarded rate). Seedling resistance test (SRT) revealed susceptible and mixed infection types, a characteristic of adult plant resistance (APR) genes. Further molecular confirmation for the presence of these genes using available microsatellite markers revealed that of the 36 lines, five lines carried Lr46+ alone and five other lines carried Lr67+ alone. Seven lines carried the combination of Lr34+ and Lr67+ while six lines confirmed to carry the combination of Lr46+ and Lr67+. Remarkably three lines carried all the three APR genes, viz. Lr34+, Lr46+ and Lr67+. All these stocks can be a source of APR multiple disease resistance genes. Ten lines were not confirmed to carry any of the genes but still had LTN and SRT results showing an infection type typical of APR genes and these can be the source of identifying newer APR genes. The resistance based on minor APR genes when combined with a few additional minor genes in the background of high yielding cultivars is expected to have high level of race non-specific resistance and to be durable.

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A lipase from the thermophilic isolate Bacillus coagulans BTS-3 was produced and purified. The enzyme was purified 40-fold to homogeneity by ammonium sulfate precipitation and DEAE-Sepharose column chromatography. Its molecular weight was 31 kDa on SDS-PAGE. The purified lipase was immobilized on silica and its binding efficiency was found to be 60%. The enzyme took 60 min to bind maximally onto the support. The pH and temperature optima of immobilized lipase were same as those of the free enzyme, i.e. 8.5 and 55ºC, respectively.  The immobilized enzyme had shown marked thermostability on the elevated temperatures of 55, 60, 65 and 70ºC. The immobilized enzyme was reused for eigth cycles as it retained almost 80% of its activity. The catalytic activity of immobilized enzyme was enhanced in n-hexane and ethanol. The immobilized enzyme when used for esterification of ethanol and propionic acid showed 96% conversion in n-hexane in 12 h at 55ºC.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Kumar Raju, P. Sugathan, T. Seshi Reddy, B. Thirumala Rao, S. Muralithar, R. Singh, R. Bhowmik and P. Madhusudhana Rao

Abstract  

The high spin level structure of 73As nucleus is studied by populating the nucleus in 64Ni(12C,p2n)73As reaction. Level scheme is revised significantly. Positive parity sequence is extended up to 33/2+ and a negative parity side band is identified and extended up to high spins 37/2. In addition about 15 new energy levels and a total of about 25 new gamma transitions were placed in the level scheme.

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Abstract

Let p(z)=j=0najzj be a polynomial of degree n. Further, letM(p,R)=max|z|=R1|p(z)|, and p=M(p,1). Then according to the well-known Bernstein inequalities, we have pnp and M(p,R)Rnp. It is an open problem to obtain inequalities analogous to these inequalities for the class of polynomials satisfying p(z) ≡ z n p(1/z). In this paper we obtain some inequalites in this direction for polynomials that belong to this class and have all their coefficients in any sector of opening γ, where 0 _ γ < π. Our results generalize and sharpen several of the known results in this direction, including those of Govil and Vetterlein [3], and Rahman and Tariq [12]. We also present two examples to show that in some cases the bounds obtained by our results can be considerably sharper than the known bounds.

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Cereal Research Communications
Authors: M. Sivasamy, M. Aparna, J. Kumar, P. Jayaprakash, V.K. Vikas, P. John, R. Nisha, K. Srinivasan, J. Radhamani, S.R. Jacob, S. Kumar, Satyaprakash, K. Sivan, E. Punniakotti, R.K. Tyagi and K.C. Bansal
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