The use of a photoinduced electron-transfer reaction for optical limiting in fullerene-containing solutions

Optical limiting was experimentally studied in C₆₀ fullerene-based multicomponent solutions that are characterized by photoinduced electron-transfer processes with the formation of ion-radical pairs. The limitation efficiency in these solutions increased as a result of enhancement of absorption in the molecular system in an excited state. It was found that the spectral and time capabilities of limiters based on fullerene-containing media can be extended with the use of radical ions.Translated from Khimiya Vysokikh Energii, Vol. 39, No. 1, 2005, pp. 32–35.Original Russian Text Copyright © 2005 by Gryaznova, Danilov, Khrebtov, Shakhverdov.     

Features of Solvent Effects on Styrene Oxidation

Correlation analysis of solvent effects on the rate of styrene oxidation showed that the uninhibited process is favored by nonspecific solvation of the substrate and enhanced cohesive energy density of the medium, that both assist the cage effect. The phenol-inhibited oxidation is much contributed by specific solvation as the result of inhibitor-solvent binding.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 958–962.Original Russian Text Copyright © 2005 by Makitra.     

Microporous Nanocomposite Material Synthesized by Sol-Gel Processing in the Presence of Cyclodextrins

It is shown that the addition of precursor, tetrakis(2-hydroxyethyl) orthosilicate, that is absolutely soluble in water to a solution of cyclodextrins (CDs) leads to the formation of a hydrogel as a result of sol-gel processes. The synthesis is performed with neither a catalyst nor heating under the conditions that are inapplicable for traditionally employed precursors (tetraethoxy- and tetramethoxysilanes). The occurrence of sol-gel processes is due to the catalytic action of CDs. At the same time, their molecules act as matrix for precipitating polysilicic acids. As a result of hydrogel calcination, xerogels were prepared with micropores and microparticles dimensions of which were determined by the sizes of CD molecules.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 3, 2005, pp. 421–425.Original Russian Text Copyright © 2005 by Shchipunov, Krekoten’, Kuryavyi, Topchieva.     

Reaction of Sterically Congested Phenols and Quinones with Organic Radicals

In the course of radiation-induced free-radical transformations of hexane and ethanol, pyrocatechol and hydroquinone derivatives, as well as their respective quinones, are more effective than phenol and resorcinol derivatives in controlling reactions that involve alkyl and hydroxyalkyl radicals. The opposite result takes place in the inhibition by phenols of hexane oxidation in which the key role belongs to the peroxyl radicals generated from the starting compounds.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 632–635.Original Russian Text Copyright © 2005 by Edimecheva, Ostrovskaya, Polozov, Shadyro.     

Reactions of Isomeric Arylchloropyruvates and Glycidates with Hydrazines

Reactions of arylchloropyruvic acids esters with aryl- and hetarylhydrazines give rise to pyrazolinedione hydrazones as a result of a tandem condensation of the substituted hydrazines with arylchloropyruvates. In contrast to this process in reaction with hydrazine hydrate a ready reduction unexpectedly occurs by Kizhner-Wolff mechanism affording 3-hydroxydihydrocinnamic acid hydrazide as the principal product. The isomeric arylglycidate reacts along the same pattern.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 5, 2005, pp. 710–717.Original Russian Text Copyright © 2005 by Mamedov, Mustakimova, Gubaidullin, Litvinov, Levin.     

Theoretical simulation of the state of an interface between two liquid phases on high-voltage polarization and microplasma discharge excitation

As a result of solving boundary problems, theoretical studies were performed that made it possible to reveal the reason for and the feasibility of excitation of microplasma discharges at an interface between two liquid phases by high-voltage polarization. The models proposed explain the formation of a barrier layer due to concentration changes near the interface on passing current through the interface under potentiostatic and galvanostatic conditions and the appearance of a field strength that suffices to excite microplasma discharges.Translated from Khimiya Vysokikh Energii, Vol. 39, No. 1, 2005, pp. 39–43.Original Russian Text Copyright © 2005 by Mamaeva, Mamaev.     

Porous Electrodes with Immobilized Enzymes: The Fractal-Percolation Properties of Supports Manufactured from Particles of Finely Divided Colloidal Graphite

The development of a porous active layer with an immobilized enzyme of a sufficiently large thickness is one of the problems that unavoidably emerge when constructing biofuel cells with high characteristics. Mounting up the thickness can be obstructed not only by the ohmic and diffusion limitations, which have been studied well enough. One more possibility of limitations (supports manufactured from finely divided colloidal graphite, FDCG), namely a “ fractal-percolation effect,” which has recently been discovered experimentally, is discussed in the paper. The essence of the effect consists of that the particles that are constituting a porous support may gather in random fractal clusters, which are connected with one another (the percolation part of the problem) with a probability that is other than unity. As a result, the electrons that are required for performing bioelectrocatalysis are capable of penetrating into a porous support only to a limited depth. Computer simulation of the fractal and percolation processes is performed in this work. As a result, quantitative relationship of the bulk concentration of FDCG in solution with the size of random fractal clusters, with the probability of their contact with one another, and with the degree of providedness of the material of the support by electrons is established. It may happen that all this information can become useful for the development of porous electrodes with an immobilized enzyme of high activity.__________Translated from Elektrokhimiya, Vol. 41, No. 8, 2005, pp. 943–953.Original Russian Text Copyright © 2005 by Chirkov, Rostokin.     

Oxidative Addition of <Emphasis Type="Italic">N</Emphasis>-Aminophthalimide to Conjugated and Nonconjugated Alkylazoalkanes

A series of γ,δ-unsaturated azo compounds was prepared by thermal isomerization of allylalkylhydrazones obtained from the simplest carbonyl compounds. The oxidation of N-aminophthalimide with lead tetraacetate in the presence of these unsaturated compounds gave rise to mixtures of adducts at the azo group, regioisomers of phthalimidoazimines. The oxidative addition of N-aminophthalimide to 1-isopropylazocycloalkenes afforded bicyclic C-isopropylazo-N-phthalimidoaziridines, but the same reaction with 2-alkylazopropenes did not result in any adducts with these conjugated azocompounds.__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 2, 2005, pp. 214–223.Original Russian Text Copyright © 2005 by Kuznetsov, Belov, Buchaka.     

Kinetics of the phase separation of a low-viscosity liquid supersaturated with gas at the intermediate and later stages

The separation kinetics of a low-viscosity liquid supersaturated with gas is studied. It is shown that the number of bubbles per unit volume at the intermediate stage of the process remains virtually constant, whereas the amount of the gas per unit volume of the solution significantly decreases, almost attaining the equilibrium value. At the later stage, small subcritical bubbles disappear due to gas transfer to large supercritical bubbles; as a result, the number of bubbles in the virtually equilibrium (as to the dissolved gas) liquid decreases. For all the stages, the kinetics of the changes in the bubble distribution function and in the amount of gas per unit volume of the solution is determined.Translated from Kolloidnyi Zhurnal, Vol. 67, No. 1, 2005, pp. 94–105.Original Russian Text Copyright © 2005 by Slezov, Abyzov, Slezova.     

Model of a Polymeric Stabilizer and Optimization of Its Compatibility with Wood

The structure and functionality of a reactive oligomer are characterized in terms of the adhesion, cohesion, and diffusion theories. The dimensions and chain-length distribution of the stabilizer are calculated using the fundamental aspects of adsorption of macromolecules on porous supports and result of an analysis of the capillary-pore system of wood. The statistical model obtained adequately reproduces the properties of stabilized wood over the investigated ranges of the process parameters.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 4, 2005, pp. 677–680.Original Russian Text Copyright © 2005 by Glazkov.     

Synthesis of 2-Functionalized 4-(Diethoxyphosphorylmethyl)-5-(1-bromoalkyl)furans and Their Reactions with Amines

Phosphorylation of esters and nitriles of 4-chloromethyl-5-alkylfuran-2-carboxylic acids with triethyl phosphite yields the corresponding phosphonates. These compounds are brominated with N-bromosuccinimide in carbon tetrachloride at the α-position of the alkyl radical. The resulting 2-(1-bromoethyl)-, 2-(1-bromopropyl)-, and 2-(1-bromoisobutyl)furans react with secondary amines following the scheme of nucleophilic substitution. The dehydrobromination product was isolated only in the reaction of ethyl 4-(diethoxyphosphorylmethyl)-5-(1-bromoisopropyl)furan-2-carboxylate with triethylamine, but its yield was low. The reactions of bromo phosphonates with lithium carbonate in DMF result in their decomposition.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 5, 2005, pp. 820–828.Original Russian Text Copyright © 2005 by Pevzner.     

Carbonyl-containing spiro-dihydrofurans in reactions with ammonium acetate and hydrazine hydrate

It has been shown that 2-spiro(3-R-6,6-dimethyl-4-oxo-2,3,4,5,6,7-hexahydrobenzofuran)-2′-(5′, 5′-dimethylcyclohexane-1′,3′-diones) undergo conversions in reactions with ammonium acetate and hydrazine hydrate into substituted dihydropyridin-2-ones and tetrahydro-1,2-diazepin-7-ones respectively as a result of ring-opening of the spirodimedonyl fragment through the corresponding amides and hydrazides of δ-keto acids. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1800–1804. December, 2005.     

Simulation of concurrent transport of counterions through a heterogeneous ion-exchange membrane

Numerical solutions of the problem of concurrent transport of two counterions in an ion-exchange membrane are presented and discussed with allowance made for the membranes heterogeneous structure. Densities of fluxes of co-ions and competing counterions are computed as a function of the current density and boundary concentrations on either side of the membrane. The obtain result is viewed as the initial product for solving multilayered problems containing membranes of other nature and diffusion layers surrounding the membrane.Translated from Elektrokhimiya, Vol. 41, No. 3, 2005, pp. 356–366.Original Russian Text Copyright © 2005 by Gnusin.     

Maximum energy trees with two maximum degree vertices

The energy E of a graph G is equal to the sum of the absolute values of the eigenvalues of G. In 2005 Lin et al. determined the trees with a given maximum vertex degree Δ and maximum E, that happen to be trees with a single vertex of degree Δ. We now offer a simple proof of this result and, in addition, characterize the maximum energy trees having two vertices of maximum degree Δ.     

Moment inequalities and convergence rates in the strong laws for ρ−- mixing random fields

By using a Rosenthal type inequality established in this paper and inspired by Berberan-Santos et al., J. Math. Chem. 37 (2005) 101–115, the complete convergence rates in the strong laws for ρ⁻ - mixing random fields are discussed. The result obtained extends the result of Ko et al., Commun. Korean Math. Soc. 19 (2004) 765–773. AMS Subject classification: 60F15     

Effect of Electron Scavengers on the Chain Reaction of Sulfo-Group Substitution for Bromine in 1-Bromo-2-hydroxynaphthalene Photosensitized with Tris(2,2′-bipyridyl)ruthenium(II)

The effect of electron scavengers (carbon tetrachloride, chloroform, and chloranil) on the chain radical-ion reaction of sulfo-group substitution for bromine in 1-bromo-2-hydroxynaphthalene photosensitized with a tris(2,2′-bipyridyl)ruthenium(II) complex was studied in an aqueous solution of sodium sulfite. It was found that “ sacrificial” electron scavengers enhanced the quantum yield of the photosensitized substitution reaction. Using the flash photolysis technique, it was shown that the electron scavengers reacted with the ruthenium(I) complex formed as a result of dissociation of a radical-ion pair in the initiation step. The rates constants for the reaction of chloroform, carbon tetrachloride, and chloranil with the ruthenium(I) complex are 1.5 × 10⁴, 1.2 × 10⁷, and 1.5 × 10⁹ dm³ mol⁻¹ s⁻¹, respectively. The chain length of the substitution reaction in aqueous solution in the presence of carbon tetrachloride is 220 ± 20.__________Translated from Khimiya Vysokikh Energii, Vol. 39, No. 5, 2005, pp. 353–357.Original Russian Text Copyright © 2005 by Ivanov Lyashkevich.     

Role of phosphates in promotion of silver catalysts for partial oxidation: II. Formation of active sites in the structure of silver phosphate under the action of a reductive medium

The morphology and chemical composition of the surface of silver phosphate are studied. The qualitative and quantitative compositions of silver phosphate are quite the same as those of the surface of the phosphorus-promoted silver catalyst. Silver particles surrounded by silver phosphate form in the subsurface region upon treatment of the sample with hydrogen. As a result, a complex catalytic system is formed in which silver phosphate is both the precursor of the reactive component (metallic silver particles) and the stabilizing matrix for this component. The system obtained is stable toward high temperature and redox reaction media.Translated from Kinetika i Kataliz, Vol. 46, No. 1, 2005, pp. 161–166.Original Russian Text Copyright © 2005 by Knyazev, Magaev, Vodyankina, Titkov, Salanov, Koshcheev, Boronin.     

Some Regularities of Deposition of an Iron-Tungsten Alloy from Citrate-Ammoniate Solutions

The process of the electrochemical deposition of an iron-tungsten alloy is investigated. It is established that, though the solution is prepared on the basis of compounds of Fe(II), stable deposition of dense deposits of the alloy begins only after a larger fraction of these compounds converts into compounds of Fe(III) as a result of oxidation by oxygen of air and anodic oxidation. The parallel evolution of hydrogen is accompanied by the process of incomplete reduction of iron ions. The current efficiency for the alloy in the working conditions exceeds 50%. The content of tungsten in the obtained alloys is weakly dependent on the current density and amounts to nearly 45% (by weight).__________Translated from Elektrokhimiya, Vol. 41, No. 8, 2005, pp. 1001–1004.Original Russian Text Copyright © 2005 by Zakharov, Gamburg.     

Secondary Structure of Globular Proteins in Adsorption Layers at the Solution-Air Interface by the Data of Fourier Transform IR Spectroscopy

The secondary structures of globular proteins of different structural types (α, (α + β), and β) are studied in the adsorption layers at the solution-air interface using Fourier transform infrared spectroscopy. Similar investigations are performed for the initial proteins in a powdered state; these data are used as a control. It is shown that, at the water-air interface, either the secondary structure of the studied proteins changes insignificantly or remains intact depending on the structural type of a protein. The adsorption of proteins of the α-helical type (bovine and human serum albumins) and the (α + β) type (lysozyme) virtually do not result in changes in their secondary structure. A protein of β-structural type, α-chymotrypsin, shows a lower stability at the water-air interface.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 3, 2005, pp. 426–432.Original Russian Text Copyright © 2005 by Yampolskaya, Tarasevich, Elenskii.     

Determination of carbon and nitrogen in meteorites using gamma-ray activation analysis

The volume concentration of carbon and nitrogen in different meteorites was determined by gamma-ray activation analysis on a microtron. The ¹¹C and ¹³N radionuclides forming in photoneutron reactions were isolated by high-temperature extraction; their positron activity was then deactivated by the method of gamma–gamma coincidence of annihilation gamma quanta. A clear correlation was found between the sample darkness and the carbon concentration; the latter was at a level of 10^–2 wt %. No correlations was observed for nitrogen; its concentration was one order of magnitude lower than that of carbon and varied over the range (2–6) × 10^–3 wt %. The results obtained suggest that carbon entered different structural defects in chondrites as a result of its redistribution upon gaseous activity on parent bodies.Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 1, 2005, pp. 52–55.Original Russian Text Copyright © 2005 by Chapyzhnikov, Badyukov, Tsipenyuk.