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  • Author or Editor: A. Mishra x
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A new generalization of the logarithmic series distribution has been obtained as a limiting case of the zero-truncated Mishra’s [10] generalized negative binomial distribution (GNBD). This distribution has an advantage over the Mishra’s [9] quasi logarithmic series distribution (QLSD) as its moments appear in compact forms unlike the QLSD. This makes the estimation of parameters easier by the method of moments. The first four moments of this distribution have been obtained and the distribution has been fitted to some well known data-sets to test its goodness of fit.

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An attempt js made to study the behaviour of recoil128I atoms in neutron irradiated I2O5 at ambient temperature. The initial retention is found to be 44±2%. However, a substantial increase /57±2%/ in the value is observed upon heating the sample at 473 K for 1 h prior to irradiation. A kinetic study of post-recoil thermal annealing of neutron irradiated material is also presented. Effect of pre-heat treatment results in a decrease of rate constants and saturation retention values at respective temperatures while the Eact for the overall process remains almost unaltered.

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The coordination complex of Cu (II) with the Schiff base derived from 4-chloroaniline with salicylaldehyde have been synthesized and characterized by micro analytical data; FT–IR, UV–Vis, FAB-mass and thermal analysis studies. Thermal data show degradation of complexes. We carried out thermal analysis at three different heating rates viz. 5, 10 and 20 °C per min. The activation thermodynamic parameters, such as activation energy (E∗), entropy of activation (ΔS∗), enthalpy of activation (ΔH∗) and Gibbs free energy (ΔG∗) have been calculated with the help of TG, DTA and DTG curves using Coats–Redfern method. The stoichiometry of the complexes are in 1:2 (M:L) molar ratio. Synthesized complex has been tested for their reactivity and substitution behaviour.

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Palladium(II) complexes of type [Pd(L)Cl2] [where L=2-aminopyridine-N-thiohydrazide (L1), (2-aminopyridine-N-thio)-1,3-propanediamine (L2), benzaldehyde 2-aminopyridine-N-thiohydrazone (L3) and salicylaldehyde-2-aminopyridine-N-thiohydrazone (L4)] have been synthesized. The thiohydrazide, thiodiamine and thiohydrazones can exist as thione-thiol tautomer and coordinate as a bidentate N-S ligand. The ligands found to act in bidentate fashion. The complexes have been characterized by elemental analysis, IR, mass, electronic, 1H NMR spectroscopic studies, and TG/DTA study. Antifungal studies of some complexes were also carried out. Various kinetic and thermodynamic parameters like order of reaction (n), activation energy (E a), apparent activation entropy (S #) and heat of reaction (ΔH) have also been carried out for one complex.

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A quick method for estimating Mishra's  generalized geometric series distribution is suggested. The variance of the estimator is obtained and using this method a study on goodness of fit is done.

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A new and simple method for selective spectrophotometric determination of uranium(VI) with 4-(2-pyridylazo)resorcinol (PAR) and N-octylacetamide into benzene over pH 7.0–9.0 is described. The molar absorptivity of the complex with 9 different amides is in the range of (0.40–3.2)·104 1·mol–1·cm–1 at the absorption maximum. Out of these, the most sensitive compound N-octylacetamide (OAA) was chosen for detailed studies in the present investigation. The detection limit of the method is 0.008 g U·ml–1. The system obeys Beer's law in the range of 0–5 g U·ml–1. The method is free from interferences of most of the common metal ions except vanadium(V) and copper(II), which are masked by proper masking agents. The composition of the complex is determined by curve-fitting method. The method has been applied for the recovery of the metal from rock samples and synthetic mixtures.

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The thermal annealing of the damage caused by /n,/ reaction has been investigated for anhydrous copper iodate in crystalline phase. Solvent extraction and fractional precipitation methods were employed to distinguish the recoil species containing recoil iodine-128 atoms. The role of reaction intermediates have been discussed.

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The kinetics of thermal decomposition of ammonium yttrium fluoride intermediates, (NH4)3Y2F9 and NH4Y2F7 were studied by a non-isothermal thermogravimetric (TG) technique at different heating rates. Kinetic parameters were determined from the TG curves by using two model-free methods, i.e. Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS). The activation energy (E) for the decomposition of (NH4)3Y2F9 was dependent on the fraction converted, α; its value was 152 kJ/mol (for α = 0.1–0.3) and 232 kJ/mol (for α = 0.4–0.8) from both models; and the pre-exponential factor (ln(A)) was 43 (for α = 0.1–0.3) and 59 (for α = 0.4–0.8). For the decomposition of NH4Y2F7, the activation energy (E) was independent of the fraction converted, α, and its value was 123 kJ/mol; the pre-exponential factor (ln(A)) was 31. The decomposition of (NH4)3Y2F9 proceeds by one-dimensional diffusion (for α = 0.1–0.3), followed by two-dimensional diffusion (for α = 0.4–0.8). The decomposition of NH4Y2F7 occurs by random nucleation and growth.

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