Theoretical-Experimental Method for Determining the Short- and Long-Term Creep Parameters of Technical Rubber in Shear

Mechanics of Composite Materials - A technique is developed for identifying the hereditary properties of technical rubber in short-term shear creep from the experimental shift the center of damped...     

Exact analytical and numerical solutions of stability problems for a straight composite bar subjected to axial compression and torsion

Based on linearized equations of the theory of elastic stability of straight composite bars with a low shear rigidity, which are constructed using the consistent geometrically nonlinear equations of elasticity theory for small deformations and arbitrary displacements and a kinematic model of Timoshenko type, exact analytical solutions of nonclassical stability problems are obtained for a bar subjected to axial compression and torsion for various modes of end fixation. It is shown that the problem of direct determination of the critical parameter of the compressive load at a given torque parameter leads to transcendental characteristic equations that are solvable only if bar ends have cylindrical hinges. At the same time, we succeeded in obtaining solutions to these equations in terms of wave formation parameters of the bar; these parameters, in turn, enabled us to find the parameter of the critical load at any boundary conditions. Also, an algorithm for numerical solution of the problems stated is proposed, which is based on reducing the problems to systems of integroalgebraic equations with Volterra-type operators and on solving these equations by the method of mechanical quadratures (finite sums). It is demonstrated that such numerical solutions exist only for certain ranges of parameters of the bar and of the parameter of torque. In the general case, they can not be obtained by the numerical method used. It is also shown that the well-known solutions of the stability problem for a bar subjected to torsion or to compression with torsion are in correct. Translated from Mekhanika Kompozitnykh Materialov, Vol. 45, No. 2, pp. 167–200, March–April, 2009.     

Synthesis of electrolytic manganese dioxide on a heated anode

Synthesis of electrolytic manganese dioxide on a heated anode was studied. The specific energy of chemical power cells fabricated using this dioxide in the Zn-Mn system is as high as 100 W h kg^?1.     

Electronic donor-acceptor interactions of anthracene with a dehydroxylated surface of silica gel and aerosil

The ability of a dehydroxylated surface of silica gel and aerosil to enter into donor-acceptor interactions with poly-acenes was demonstrated by methods of steadystate and kinetic spectrofluorometry. The anthracene molecule forms EDA complexes with electron-acceptor sites of silica gel and aerosil in the ground state (charge-transfer complex, CTC) and the excited state (exciplex). At a degree of coverage of the silica gel and aerosil surfaces by polyacene molecules of 10^–1–10^–3% of a monolayer, energetic and structural inhomogeneity of the OH groups of silica gel appears. Silica gel possesses stronger electron acceptor sites; the electron-acceptor sites of aerosil are more accessible to EDA interactions and more monotypic. Vacancy defects of the SiO₂ matrix are suggested as accepting sites.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 6, pp. 693–698, November–December, 1986.     

Recovery of Gold from Cyanide Solutions Using Activated Carbon Sorbent Based on Lignite

Recovery of gold cyanide complexes was studied using sorbents prepared from Kansk-Achinsk lignite.     

Non-uniformly scaled buckling modes of reinforcing elements in fiber reinforced plastic

We consider a problem about non-uniformly scaled buckling modes of isolated fiber (without accounting of interaction with the surrounding epoxy) or bundle of fibers, which are structural elements of fiber reinforced plastics under the transverse tension (compression) and shear stresses in prebuckling state. Such initial state is formed in fibers and bundles of fibers at tension-compression tests of flat specimens from cross ply composites with unidirectional fibers. For problem statement we use equations recently constructed by reduction of consistent version of geometrically nonlinear equations of theory of elasticity to one dimensional equations of rectilinear beams. Equations are based on refined shear S. P. Timoshenko model with accounting of tension-compression stresses in transverse directions. We give theoretical explanation of developed phenomenon as reducing shear modulus of elasticity of fiber reinforced plastic during the increasing of shear strains. We show that under the loading process of specimens under review uninterruptedly structure reconstruction of composite trough implementation and uninterruptedly changing of internal buckling modes at changing wave parameter is feasible.     

Cyclic evolution of hydrogen during low-temperature thermolysis of water by adsorbed Re3Cl9 complex

The ability was studied of an Re₃Cl₉ cluster complex adsorbed on a silica surface to cause the thermochemical decomposition of water at a temperature of 670–770°K. In the multiply repeated cycles: water sorption, heating, water sorption, etc., the complex retains its ability to evolve hydrogen on heating to the same level. It was found that at room temperature, during the sorption of water, which occurred after heating, evolution of oxygen takes place. A reversible character of the interaction of the adsorbed rhenium complex with water in a two-stage thermochemical cycle has been postulated.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 26, No. 3, pp. 365–367, May–June, 1990.     

Spectral detection of the primary products in the photodehydrogenation of alcohols by quinones at 77‡ K

The formation of semiquinone ions in the first stage of photochemical reactions between various quinones and alcohols at 77 K has been detected from absorption and electron paramagnetic resonance (EPR) spectra. The mechanism of the photochemical reaction is discussed.The principal results have been reported to the All-Union Conference on the Study of Structure and Reactivity by Physical Methods [1].