On the evolution equations for reduced density operators in quantum open systems

Evolution equations for transition probabilities of reduced density operators in quantum open systems are derived. Information contained in such equations is obtained from spectral resolutions and the role of memory kernels is elucidated within the scenario of many body theory as a function of the self-energy fields. As an analytical example of this formulation relaxation times for dissipative systems are evaluated in terms of the interaction between subsystems.     

Platinum-Ruthenium Catalysts,Manufactured by Means of Ion Exchange in Nafion Layers

Catalytic layers of platinum-ruthenium of preliminarily specified compositions are manufactured with the aid of ion exchange and subsequent chemical and electrochemical reduction in polymeric Nafion films applied onto carbonaceous materials and inside a standard Nafion 117 membrane. The procedure used for conducting the ion-exchange procedure ensures a high process rate and a short time required to conduct it, which makes it possible to obtain large roughness factors at relatively small contents of platinum metals (0.1–0.2 mg cm^?2). The electrochemical activity of catalyzed membrane samples for methanol oxidation in aqueous and sulfuric acid solutions is close to the activity of standard E-TEK platinum-ruthenium catalysts.     

Heterocycles derived from the condensation of 1,3-propanediamine with phthalic acid derivatives

The condensation of phthalic anhydride with 1,3-propanediamine afforded N-(o-carboxybenzoyl)-1,3-propanediamine (I) which by intravolecular cyclization was transformed into 2,3,4,6-b-tetrahydropyrimido[2,1-a]isoindol-6-one (II) rather than the benzodiazonine (III). An intermediate in the condensation is proposed. The reaction of 1,3-propanediamine with dimethyl phthalate also did not afford III, but rather a more complex product, dibenzo[c,l]-1,6,10,15-tetraazacyclooctadecane-5,11,16,22-tetraone (IX). Reaction of 1,3-propanediamine with phthaloyl chloride gave 6,13-propanodibenz[c,h]-1,6-diazecine-5,7,12,14-tetrone (XII). Spectroscopic data of the heterocycles obtained and chemical properties of II are given.     

Role of association on protein adsorption isotherms. Beta-lactoglobulin A adsorbed on a weakly hydrophobic surface

This paper explores the role of association on the adsorption isotherms of beta-lactoglobulin A on a weakly hydrophobic stationary phase at 4 degrees C and mobile phases of 0.85 M and 1 M ammonium sulfate, pH 4.5. The isotherms, obtained by frontal analysis, show an S-shape and the corresponding Scatchard plots indicate positive cooperativity. The slopes and intercepts of the Scatchard plots at low solute concentration are analyzed in terms of two species--a promoter and a higher order stronger adsorbing species. An explicit equation of the isotherm is developed based on this model, and this expression is shown to reproduce the isotherm shape using the appropriate derived parameters. It is further shown from this equation that a Langmuir-shaped adsorption isotherm can be obtained if the higher order associate or aggregate binds weaker to the support than the promoter. These results indicate that protein-protein interactions and the formation of associates can play a significant role on the shape of the isotherm and ultimately on the behavior of the species in preparative scale chromatography.     

Construction of Quaternary Stereocenters by Nickel‐Catalyzed Heck Cyclization Reactions

A nickel‐catalyzed Heck cyclization for the construction of quaternary stereocenters is reported. This transformation is demonstrated in the synthesis of 3,3‐disubstituted oxindoles, which are prevalent motifs seen in numerous biologically active molecules. The method shows broad scope, proceeds in synthetically useful yields, and provides a rare means to construct stereochemically complex frameworks by nonprecious‐metal catalysis.     

Interaction of a two‐level cyclic XY n‐spin model with a two‐mode cavity field in off‐resonant states

The interaction of the XY n‐spin cyclic model with a two‐mode cavity field in the rotating‐wave approximation is investigated in the framework of a generalized Jaynes–Cummings two‐level system consisting of the vacuum state and a thermally averaged manifold of excited sates. Computation of the energy of this manifold allows this interaction to be examined in off‐resonant states. Time evolution of the population inversion, photon distribution, and temperature distribution for an excited initial state are computed via second‐ and third‐order perturbation expansion of the time evolution operator matrix elements for the excited and ground states, respectively and for an ideal squeezed initial coherent state of the cavity field. It was assumed that the two modes have initially the same photon distribution. The pattern of the spin population inversion appears as a manifestation of multiple and complicated inerferences, which is mathematically reflected in a double discrete summation that appears in the calculation of the dynamics. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Electrochemical carboxylation of β-cyclodextrin/1-(3-phenoxyphenyl)-1-chloroethane inclusion complex on a glassy-carbon cathode in anhydrous dimethylformamide

Inclusion complexes of β-cyclodextrin with 1-(3-phenoxyphenyl)-1-chloroethane in the “guest-host” molar ratio of 1: 2 are synthesized, isolated, and characterized. It is shown that preparative electrocarboxylation of β-cyclodextrin/1-(3-phenoxyphenyl)-1-chloroethane inclusion complex on a glassy-carbon cathode in dimethylformamide leads to the formation of S-form of 2-(3-phenoxyphenyl)propionic acid (S-Phenoprofen) with an optical yield of ～20%. In addition to the acid, a dimer of electrochemically generated intermediates forms.     

Electrochemical reduction of CO2 in the presence of 1,3-butadiene using a hydrogen anode in a nonaqueous medium

The possibility of anodic generation of a solvated proton on a gas-diffusion electrode in an aprotic medium in the presence of carbon dioxide and 1,3-butadiene has been demonstrated. Formic acid was shown to be the only product of the reaction in the initially aprotic medium with the use of a hydrogen gas-diffusion anode. The influence of the counterion on the reactivity of the CO₂ ^.− radical anion in electrocarboxylation was shown experimentally. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 295–300, February, 1999.     

Properties of the low-lying excited states in even-even nuclei around the closed shell N=82

The properties of low-lying states in ¹³⁶Ba and ¹⁴⁴Nd are calculated within the quasiparticle phonon model. It is shown that the strong quadrupole interaction in the particle-particle channel leads to the appearance of low-lying isovector excitations. Due to this reason, there are two branches in the lowlying part of the spectrum, an isoscalar and an isovector one. Both branches show peculiar regularities of E2 and M1 transitions.