Photocrystallization in amorphous thin films of Se70Te30−xCdx

Summary The present paper reports a study of photocrystallization in a-Se₇₀Te_30−xCd_x films (0≤x≤4). The photocrystallization is achieved by shining white light at room temperature for different exposure times. The results indicate that the photocrystallization is suppressed on addition of Cd in binary Se₇₀Te₃₀ system. This is explained in terms of the structure of Se-Te-Cd system. Work supported by University Grants Commission. The authors of this paper have agreed to not receive the proofs for correction.     

Effect of antimony on glass transition and thermal stability of Se<Subscript>78−x</Subscript>Te<Subscript>18</Subscript>Sn<Subscript>2</Subscript>Sb<Subscript>x</Subscript> (<Emphasis Type="Italic">x</Emphasis> = 0, 2, 4 and 6 at.%) multicomponent glassy alloys

Multicomponent glassy alloys Se_78?xTe₁₈Sn₂Sb_x (x?=?0, 2, 4 and 6) have been synthesized using melt quench technique. The prepared samples have been characterized by X-ray diffraction technique and differential scanning calorimetry (DSC). Glass transition kinetics of Se_78?xTe₁₈Sn₂Sb_x (x?=?0, 2, 4 and 6 at.%) glassy alloys has been examined using DSC. DSC runs have been recorded at different heating rates (5, 10, 15 and 20 K min^?1) for each sample under investigation. Heating rate dependence of glass transition temperature (T_g) has been studied using Lasocka empirical relation. The activation energy of glass transition has been evaluated using Kissinger and Moynihan’s relation. The effect of antimony concentration on glass transition temperature and activation energy has been investigated in the prepared samples. Glass-forming ability and thermal stability of Se_78?xTe₁₈Sn₂Sb_x (x?=?0, 2, 4 and 6) glassy alloys have been monitored through the evaluation of thermal stability using Dietzal relation, Hurby parameter, and Saad and Poulin parameter. The above-mentioned parameters are found to be compositionally dependent, which indicates that among the studied glass samples the stability is maximum for Sb at 2% content.     

Parametric Excitation of Electron-Acoustic Mode in a Plasma of Two-Temperature Electrons

Using hydrodynamical model of the two-electron-temperatere plasma, the analytical investigation of parametric instability of electron-acoustic wave has been made. It is found that the growth rate decreases with increasing concentration ratio of the hot to the total electrons n_h0/n₀. The growth rate is found to be more for      

Synthesis of l-(N-acelylpiperidino)-4-aryl semicarbazides as possible anticonvulsants

Six 1-(N-acetylpiperidino)-4-aryl semicarbazides were synthesized from ethyl-N-piperidino-aeetatc which on treatment with hydrazine hydrate was converted into N-piperidinoacethydrazide. The resulting hydrazide on treatment with the appropriate arylisoeyanales formed l -(N-acelyl-piperidino)-4-aryl semicarbazides. Amongst these piperidinosemicarbazides, three compound possessed low anticonvulsanl activity and provided 20-40% protection against pentylenetetrazol-induced convulsions in mice. All piperidino semicarbazides (0.1 mM) possessed antihemolytic activity (13-35%) and caused 40-72% inhibition of monoamine oxidase activity of rat brain homogenates at a final concentration of 0.3 mM.     

Lewis acid catalyzed regioselective ring opening of azetidines with alcohols and thiols

An efficient synthesis of amino ethers and amino thioethers has been achieved via the ring cleavage of N-tosylazetidines with alcohols or thiols. The reactions were studied in the presence of various Lewis acids and BF₃·OEt₂ was found to be the most efficient. The products were obtained in modest to good yields under very mild conditions in 5-15 min.     

Probability distribution for the number of cycles between successive regime transitions for the Lorenz model

The Lorenz model has been widely used for exploring many real world problems. In this paper we obtain, with the help of an invariant manifold technique, the return map for the maximum value of the variable x of the model and use this return map to derive the simple, empirically obtained, regime transition rules for forecasting regime changes and length in the new regime for the model. The probability distribution for number of cycles between successive regime transitions of the Lorenz model may be of interest in many disciplines. We apply the Perron-Frobenius algorithm over the return map to estimate the probability distribution for the number of cycles between successive regime transitions. These probabilities are also estimated for the forced Lorenz model, which is a conceptual model to explore the effects of sea surface temperature on seasonal rainfall.     

Purification and Characterization of a Zinc-Dependent Cinnamyl Alcohol Dehydrogenase from Leucaena leucocephala,a Tree Legume

A cinnamyl alcohol dehydrogenase (CAD) from the secondary xylem of Leucaena leucocephala has been purified to homogeneity through successive steps of ammonium sulfate fractionation, DEAE cellulose, Sephadex G-75, and Blue Sepharose CL-6B affinity column chromatographies. CAD was purified to 514.2 folds with overall recovery of 13 % and specific activity of 812. 5 nkat/mg. Native and subunit molecular masses of the purified enzyme were found to be ～76 and ～38 kDa, respectively, suggesting it to be a homodimer. The enzyme exhibited highest catalytic efficiency (Kcat/Km 3.75 μM^?1 s^?1) with cinnamyl aldehyde among all the substrates investigated. The pH and temperature optima of the purified CAD were pH 8.8 and 40 °C, respectively. The enzyme activity was enhanced in the presence of 2.0 mM Mg²⁺, while Zn²⁺ at the same concentration exerted an inhibitory effect. The inclusion of 2.0 mM EDTA in the assay system activated the enzyme. The enzyme was inhibited with caffeic acid and ferulic acid in a concentration-dependent manner, while no inhibition was observed with salicylic acid. Peptide mass analysis of the purified CAD by MALDI-TOF showed a significant homology to alcohol dehydrogenases of MDR superfamily.     

Kinetic study of copolymerization of linalool and methyl methacrylate initiated by selenonium ylide

Free radical copolymerization of an acyclic monoterpenoid linalool (LIN) and methyl methacrylate (MMA) in dioxan was carried out in dilatometer under an inert atmosphere of nitrogen for 90 min at 60 ± 1°C by using diphenyl selenonium 2,3,4,5‐tetraphenylcyclopentadienylide (selenonium ylide) as an initiator. The kinetic expression of the reaction is R_p ∝ [ylide]^0.5[MMA]^1.0[LIN]^1.0. The activation energy of copolymerization was estimated to be 43.7 kJ mol^?1. The formation of a functional copolymer is evidenced by spectral analysis. The copolymer was characterized by FTIR, ¹H NMR, ¹³C NMR, DSC, and TGA analysis. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 43: 43–52, 2011     

Relationships of labile pool of Mn with some general soil properties and extractable soil Mn contents

Labile pool (E-value) of Mn and extractable soil Mn content using six multinutrient extractants were estimated in fifty surface (0–15 cm) soil samples. Labile pool of Mn was poorly correlated to the general soil properties and modified Olsen’s-; 0.01 M CaCl₂- and 1 M MgCl₂-extractable Mn contents but it was positively and significantly correlated to diethylene triamine pentaacetic acid (DTPA), pH 7.3; ammonium bicarbonate + DTPA (pH 7.6); and Mehlich-3-extractable soil Mn contents. The multinutrient extractants involving only simple salt solutions were not useful to assess the availability of Mn in soils.