Determining Role of the Chain Mechanism in the Temperature Dependence of the Gas-Phase Rate of Combustion Reactions

It is shown that the strong dependence of the rate of gas-phase combustion reactions on temperature is determined by the high values of the reaction rate constants of free atoms and radicals. It is established that with a branched chain mechanism, a special role in the reaction rate temperature dependence is played by positive feedback between the concentrations of active intermediate species and the rate of their change. The role of the chemical mechanism in the temperature dependence of the process rate with and without inhibitors is considered.     

Study of the Optical Atmospheric Distortions using Wavefront Sensor Data

Russian Physics Journal - The paper studies the optical turbulence structure at the Large Solar Vacuum Telescope of the Baikal Astrophysical Observatory. Some results on the study of the wavefront...     

Method of Search for Hidden Photons of Cold Dark Matter Using a Multi-Cathode Counter

Physics of Atomic Nuclei - We propose a method of search for cold dark matter, which presumably consists of hidden photons, by detecting single electrons emitted from the surface of the metal...     

Structural-chemical activity criteria for catalysts of deep oxidation

Russian Journal of General Chemistry -     

Formation of needlelike crystallites during growth of diamond films by chemical vapor deposition

Diamond polycrystalline films have been grown by chemical vapor deposition from a hydrogenmethane mixture. The phase composition and structure of the films were studied using Raman spectroscopy, electron microscopy, and thermogravimetry. It is found that, upon heating in air, the oxidation of the carbon material forming the films occurs at significantly different temperatures, depending on the degree of its order and the crystallite size. This difference is used for selective oxidation of the least ordered fine-grained component of the films. The material obtained by this selective oxidation of the films consists of diamond crystallites shaped like regular micrometer-sized tetragonal pyramids with a radius of tip curvature of several nanometers.     

Fluorine-containing poly(carbonate-block-siloxane) copolymers

On the basis of carbofunctional oligo(??,??-bisphenoxy-trifluoropropyl(methyl)siloxanes, bisphenols, and bisphenol A bis(chloroformate), novel fluorine-containing poly(carbonate-block-siloxanes) are synthesized and characterized. The presence of trifluoropropyl groups in siloxane blocks of the copolymers decreases the sorption of hydrocarbons by 4 to 6 wt % instead of the 60 wt % for usual poly(carbonate-block-dimethylsiloxanes). Films based on fluorine-containing poly(carbonate-block-siloxanes) retain their high strength characteristics in the swollen state (??_b = 20 MPa).     

Preparation of organoalkoxysiloxanes by partial acidolysis of organoalkoxysilanes

Partial polycondensation of RSi(OMe)₃ (R = C₆H₅, CH₃) by the reaction with AcOH in the presence of HCl is studied. Oligoorganomethoxysiloxanes are obtained of the average composition [RSi(OMe)O]₄, [RSi (OMe)_4/6O_7/6]₆, RSi(OMe)_0.5O_1.25]₈, and [RSi(OMe)_0.4O_1.3]₁₀. Using the method of ²⁹Si NMR spectroscopy they were shown to contain three types of structural fragments: RSi(OMe)₂O-, RSiOMe(O-)₂, RSi(O-)₃. Based on the kinetic data, on the composition, properties, and the ²⁹Si NMR spectroscopy data of the products the conclusion is made that the obtained compounds have polycyclic structure with branched fragments. Using the GLC method the reaction was shown to have an induction period, whose duration can be substantially shortened by addition of HCl or methanol.     

Polymerization of styrene in the presence of organosilicon surfactants of various natures

The properties of polymer suspensions obtained with the use of organosilicon surfactants of various structures are compared. The polymer suspensions are characterized by a narrow particle size distribution and contain functional groups on their surface.     

<Emphasis Type="Italic">L</Emphasis><Subscript><Emphasis Type="Italic">p</Emphasis>,<Emphasis Type="Italic">q</Emphasis></Subscript>-Cohomology and Normal Solvability

We consider some problems concerning the L _p,q -cohomology of Riemannian manifolds. In the first part, we study the question of the normal solvability of the operator of exterior derivation on a surface of revolution M considered as an unbounded linear operator acting from L_p^k (M) into L^k+1_q (M). In the second part, we prove that the first L _p,q-cohomology of the general Heisenberg group is nontrivial, provided that p < q. Received: 17 January 2006 Supported by INTAS (Grant 03–51–3251) and the State Maintenance Program for the Leading Scientific Schools of the Russian Federation (Grants NSh 311.2003.1, NSh 8526.2006.1).