A Semiclassical Theory of a Dissipative Henon—Heiles System

A semiclassical theory of a dissipative Henon—Heiles system is proposed. Based on -scaling of an equation for the evolution of the Wigner quasiprobability distribution function in the presence of dissipation and thermal diffusion, we derive a semiclassical equation for quantum fluctuations, governed by the dissipation and the curvature of the classical potential. We show how the initial quantum noise gets amplified by classical chaotic diffusion, which is expressible in terms of a correlation of stochastic fluctuations of the curvature of the potential due to classical chaos, and ultimately settles down to equilibrium under the influence of dissipation. We also establish that there exists a critical limit to the expansion of phase space. The limit is set by chaotic diffusion and dissipation. Our semiclassical analysis is corroborated by numerical simulation of a quantum operator master equation.     

Cesàro α-Integrability and Laws of Large Numbers I

For a sequence of integrable random variables, we introduce a new set of conditions called Cesàro -Integrability and Strong Cesàro -Integrability and show that, for <1/2, these conditions that are strictly weaker than Cesàro Uniform Integrability and Strong Cesàro Uniform Integrability respectively, are sufficient for WLLN and SLLN to hold for a sequence of pairwise independent random variables. For some special kinds of dependent sequences of random variables also, Cesàro -integrability for appropriate is shown to be sufficient for WLLN to hold.     

Estimation of chloride in oxidizing media by means of ion-selective electrodes

Chloride concentrations down to the ppm level in a large excess of chlorate or perchlorate can be quantitatively estimated by use of chloride ion-selective electrodes (ISEs). Similarly traces of chloride in chromic acid solutions can be estimated with a heterogeneous silicone-rubber based chloride ISE. However, homogeneous chloride ISEs pose a problem for practical applications, because their response in chromic acid solutions changes with time owing to chemical attack on the membrane surface. In permanganate solutions, both homogeneous and heterogeneous type electrodes can be used for monitoring chloride ions. The Orion electrode, however, was found to show a slightly super-Nernstian response in such solutions. The presence of 10(-3)M iron(III) had no adverse effect on the performance of these electrodes in permanganate solutions.     

Computational elimination of interelemental interference in the analysis of copper, cobalt and nickel in polymetallic sea bed nodules by flame atomic absorption spectrometry

A method has been described for the estimation of Cu, Co and Ni in polymetallic sea bed nodule samples by flame atomic absorption spectrometry using single component calibration standards. Interelemental interference plays a crucial role in the estimation of Cu, Co and Ni by flame AAS. Calibration by multicomponent matrix matching standards often fails because of wide variations in the compositions of actual samples. Cu, Co and Ni values are depressed in the presence of appreciable amounts of Fe and Mn present in the sea nodule matrix. Observed interferences have been eliminated computationally using a two parameter theoretical model. The method has been successfully applied for the estimation of Cu, Co and Ni in real life sea nodule samples by flame AAS using single component calibration standards.     

Quantum chemical study of hydrogen abstraction reactions of the ethynyl radical with hydrogen compounds (C2H+HX)

We have theoretically investigated the hydrogen abstraction reactions of ethynyl radical with simple hydrogen compounds, C₂H+HX, using quantum chemical computations. Computations have been performed using the density functional theory with the recently proposed MPW1K functional and the 6-311++G(3df,2p) basis set. An analysis of the resulting energy barriers for hydrogen abstraction reactions has been carried out using the bond dissociation energy of the breaking X–H bond and DFT-based reactivity parameters to rationalize the reaction behavior.     

Spectroscopic studies on Co(II), Ni(II) and Cu(II) complexes with a new macrocyclic ligand: 2,9-dipropyl-3,10-dimethyl-1,4,8,11-tetraaza-5,7:12,14-dibenzocyclotetradeca-1,3,8,10-tetraene

Cobalt(II), nickel(II) and copper(II) complexes containing a tetradentate macrocyclic nitrogen donor ligand i.e. 2,9-dipropyl-3,10-dimethyl-1,4,8,11-tetraaza-5,7:12,14-dibenzocyclotetradeca-1,3,8,10-tetraene have been synthesized and characterized by elemental analysis, molar conductance, magnetic moments, mass, (1)H NMR, IR, electronic and EPR spectral studies. All the complexes are of high spin type and possess four-coordinated tetrahedral, five-coordinated square pyramidal and six-coordinated octahedral/tetragonal geometry. The ligand and its metal complexes were also screened against the growth of some bacteria and plant pathogenic fungi in vitro.     

Benzyl chloride transformation as a probe for electron transfer on Rh/TiO2 under SMSI state

Benzyl chloride transformation has been studied over Rh/TiO₂ under SMSI state to give evidence for the transfer of electrons from support to metal.

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Rh/TiO₂, . .

     

Fluoroaromatic-fluoroaromatic interactions between inhibitors bound in the crystal lattice of human carbonic anhydrase II

Intermolecular interactions of eleven different fluoroaromatic inhibitors are probed within the scaffolding of the crystal lattice of Phe-131-->Val carbonic anhydrase II. The degree and pattern of fluorine substitution on the inhibitor benzyl ring modulate its size, shape, and electronic character. In turn, these properties affect the geometry of intermolecular interactions between the fluoroaromatic rings of two different inhibitor molecules bound in the crystal lattice, as determined by X-ray crystallography. Depending on the degree and pattern of fluorine substitution, we observe a face-to-face (aromatic-aromatic) interaction, an atom-to-face (carbonyl-aromatic) interaction, or no interaction at all. These interaction geometries are analyzed with regard to van der Waals, electrostatic, and possible charge-transfer effects. For the aromatic-aromatic interactions investigated in this study, with aromatic ring quadrupoles specifically "tuned" by the degree and pattern of fluorination, the structural results suggest that London forces and charge-transfer complexation dominate over weakly polar electrostatic interactions in the association of aromatic ring pairs.