Problems on Nonstationary Interaction of Structural Elements with Shock Waves

Experimental investigations into the interaction of rigid and elastic structure elements with a shock wave in water and in air are reviewed. Investigation techniques are described and the nonstationary behavior of elements is analyzed     

The elasticity of a magnetic-fluid membrane

For a magnetic-fluid membrane, the critical pressure drop is determined experimentally using thermodynamic and hydrostatic methods. It is found that the value of the critical pressure drop calculated from the data of the thermodynamic method exceeds by ～30% the value of this parameter measured by the hydrostatic method. The overstated value of the critical pressure drop obtained using the indirect thermodynamic method is explained by the approximate nature of the analytical model lying at its basis, which does not take into account the relaxation character of pondermotive elasticity. The static and thermodynamic coefficients of pondermotive elasticity of a magnetic-fluid membrane sample are calculated, and the results are used to estimate the membrane displacement by the moment of its breakage.     

Electrochemical synthesis of perfluoropolyethers by the Kolbe method

Electrochemical dimerization of hexafluoropropylene oxide dimer and trimer acids on SU-2000 glassy carbon, bulk platinum, and SU-2000 electrodes modified with platinum-group metals in acetonitrile in the presence of water was studied at various concentrations of the starting substance and different degrees of neutralization of the starting acid. Also, the possibility was examined of obtaining some perfluoropolyethers in a single process by cross-condensation of several starting perfluorocarboxylic acids, followed by separation of the products by physicochemical methods.     

On hyperbolic systems of equations with zero generalized Laplace invariants

A criterion for the interruption of the sequence of generalized Laplace invariants is found. A general solution of a system of linear hyperbolic equations with zero invariants is constructed.     

The influence of high-frequency electromagnetic fields on the critical micelle concentration in aqueous solutions of sodium dodecyl sulfate

It was established that the critical micelle concentration in solutions of sodium dodecyl sulfate changed under the action of high-frequency electromagnetic fields (60, 120, and 160 MHz). The thermodynamic functions of micelle formation were calculated. Original Russian Text ? I.E. Stas’, O.P. Mikhailova, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 2, pp. 397–399.     

Destruction of polymeric cobalt(ii) trimethylacetate. Synthesis and structures of new complexes Co9(μ3-OH)6(μ-OOCCMe3)12(OCMe2)4 and Co6(μ4-O)2(μ-OOCCMe3)10(η-HOOCCMe3)4

Russian Chemical Bulletin -     

Self‐assembly of well‐defined amphiphilic polymeric miktoarm stars,dendrons, and dendrimers in water: The effect of architecture

Five polymeric architectures with a systematic increase in architectural complexity were synthesized by “click” reactions from a toolbox of functional linear polymers and small molecule linkers. The amphiphilic architectures ranged from a simple 3‐miktoarm star block copolymer to the more complex third generation dendrimer‐like block copolymer, consisting of polystyrene (PSTY) and polyacrylic acid (PAA). Micellization of these architectures in water at a pH of 7 under identical ionic strength gave spherical micelles ranging in size from 9 to 30 nm. Subsequent calculations of the PSTY core density, average surface area per PAA arm on the corona‐core interface, and the relative stretching of the PAA arms provided insights into the effect of architecture on the self‐assembly processes. A particular trend was observed that with increased architectural complexity the hydrodynamic diameter, radius of the core in the dry state and the aggregation number also increased with the exception of the third generation dendrimer. On the basis of these observations, we postulate that thermodynamic factors controlling self‐assembly were the entropic penalty of forming PSTY loops in the core counterbalanced by the reduction in repulsive forces through chain stretching. This results in a greater number of aggregating unimers and consequently larger micelle sizes. The junction points within the architecture also play an important role in controlling the self‐assembly process. The G3 dendrimer showed results contradictory to the aforementioned trend. We believe that the self‐assembly process of this architecture was dominated by the increased attractive forces due to stretching of the PSTY core chains to form a more compact core. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6292–6303, 2009     

Adsorption of Cationic Surfactants on Highly Dispersed Silica

Comparative study was made of adsorption of cationic surfactants, decamethoxine, ethonium, and cetyltrimethylammonium bromide, on a highly dispersed amorphous silica at different pH values. Contrary to the adsorption of monoquaternary ammonium compound, cetyltrimethylammonium bromide, the adsorption of bis(quaternary ammonium) compounds, ethonium and decamethoxine, was found to be caused mainly by electrostatic interaction. The adsorption of antiseptic decamethoxine is reversible at pH 6; this may be used to design carriers capable of controlled drug release into the surrounding medium.     

A Novel Streptavidin–luciferase Fusion Protein: Preparation,Properties and Application in Hybridization Analysis of DNA

A streptavidin–luciferase fusion protein comprising the thermostable mutant form of firefly luciferase Luciola mingrelica and minimal core streptavidin was constructed. The streptavidin–luciferase fusion was mainly produced in a tetrameric form with high luciferase and biotin‐binding activities. It was shown that fusion has the same K_m values for ATP and luciferin and the bioluminescence spectra as initial luciferase. The linear dependence of the bioluminescence signal on the content of the fusion was observed within the range of 10^?18–10^?13 mol per well. Successful application of obtained fusion in a biospecific bioluminescence assay based on biotin–streptavidin interactions was demonstrated by the example of a specific DNA hybridization analysis. A DNA hybridization analysis for Escherichia coli cells identification was developed using unique for these cells gadB fragment encoding glutamate decarboxylase. The amplified biotinylated GadB fragments were hybridized with the immobilized oligonucleotide probes; then, the biotin in the DNA duplexes was detected using the streptavidin–luciferase fusion protein. To reach the high sensitivity of the assay, we optimized the conditions of the assay. It was shown that the use of Pluronic for plate modification resulted in a significant reduction in the DNA detection limit which finally was 0.4 ng per well.