Study of sound-absorbing properties of glass-fiber reinforced materials used in engineering

© Published under licence by IOP Publishing Ltd. Modern engineering makes high demands to the noise level in the passenger compartment or cabin of KAMAZ. An effective means of dealing with noise is to use sound absorbing materials produced by the automotive industry. To increase sound-absorbing capacity of materials and structures using glass fibre reinforced polyurethane foams (PUF) obtained by the technology Fiber Composite Spraying

Sulfur composite materials based on sulfide containing industrial waste

© 2017 Trans Tech Publications, Switzerland. A technology for the production of sulfur composite materials based on waste from BaCl 2 at Karpov Mendeleyevsk Plant (Russia) was developed. The physical chemical and quantum chemical studies were performed for the “sulfur – sulfide containing industrial waste–filler” system. The usage of sulfide ion CaS enables sulfur activation to promote the chemical interaction between the components and synthesis of sulfides and sulfur materials with high physical mechanical properties from them

Hardy-type inequalities with power and logarithmic weights in domains of the euclidean space

We consider Hardy-type inequalities in domains of the Euclidean space for the case when the weight depends on the distance function to the domain boundary and has power and logarithmic singularities. We prove several new inequalities with sharp constants. Original Russian Text © N.I. Manina and A.Ya. Sultanov, 2011

Becker type univalence conditions for harmonic mappings

© 2016, Allerton Press, Inc.We obtain Becker type univalence conditions for locally univalent harmonic mappings defined in one of the following domains: the unit disc, a halfplane, the exterior of the unit disc and prove a generalization of John’s univalence condition

Effects of a hydrogen sulfide donor on spontaneous contractile activity of rat stomach and jejunum

We studied the effect of sodium hydrosulfite (NaHS), a donor of hydrogen sulfide (H2S), on spontaneous contractive activity of isolated preparations of rat stomach and jejunum under isometric conditions. NaHS in concentrations of 10-200 μM reduced the amplitude, tonic tension, and frequency of contractions of the preparations. Blockade of K+ channels with a non-specific antagonist tetraethylammonium (10 mM) increased contraction amplitude in the stomach strip and jejunum segment. The effects of NaHS on all parameters of contractile activity of the stomach and jejunum were fully preserved against the background of tetraethylammonium application. These data suggest that H2S in physiologically relevant concentrations inhibited spontaneous contractile activity of smooth muscle cells in rat stomach and jejunum by reducing the amplitude and frequency of contractions and decreased tonic tension without affecting the function of voltage- and calcium-dependent K+ channels. © 2014 Springer Science+Business Media

Production of sulfur composite materials from sulfur containing waste for construction applications

Production of high-quality sulfur composite materials with high performance. The physicochemical analysis and quantum chemical studies established that high physical and mechanical properties of the developed materials resulted from a chemical interaction between the components, which favored the formation of a compact homogeneous structure of the material

Sulfur composite technology from oil refinery waste

© Research India Publications.Oil and gas waste is a valuable material for chemical industry and new material intensive alternative. The article studies a possibility of obtaining inorganic sulfides from elemental sulfur and an active silica containing material with better mechanical and physical properties and analyses their formation. The usage of an aluminum chloride activator allows activating sulfur and silica components of materials that contributes to obtain unyielding and long-lasting sulfur composites having better performance properties. To understand the chemical processes developing in the system and prove new chemical bond formation, the quantum-chemical research using software products is undertaken. The comparative thermodynamic assessment of insertion and replacement reactions in triple and singlet state of sulfur is carried out. The impact of silicagel premodification with aluminum chloride on reaction with sulfur and calcium sulphide formation is defined. The quantum-chemical calculation results confirm the chemical reaction possibility between sulfur and silicagel modified with aluminum chloride. According to the research results, the schemes of obtaining silica containing materials from opal cristobalite rock of various deposits are suggested. According to the research results, we can offer the manufacture technology of inorganic sulfides and sulfur composites employing an activator-aluminum chloride. A key technology scheme of sulfur composite manufacturing from inorganic sulfides is developed. The acquired data on usage of interaction mechanisms of sulfur with various inorganic compounds can provide background for developing recycling technologies of sulfur obtained in the process of oil refining into sulfides and multipurpose materials

Theoretical evaluation of rheological state of sand cement composite systems with polyoxyethylene additive using topological dynamics concept

© 2016 Trans Tech Publications, Switzerland.Presents the results of studies of contemporary materials in the field of rheological state. The topological mortar structure has been provided by theoretical evaluation of the rheological state of the cross-linked solutions and the experimental viscosity data of the sand cement mortar which has been modified by water-soluble additive – polyoxyethylene. The general model has been made for the structure of non-Newtonian liquideous systems including dilatant, pseudoplastic bodies with two main rheological active components in their structure – rigid and viscous phases. It is shown that in pseudoplastic systems, as the shear stress increases, the viscous phase grows because of the reduction of rigid phase content. In dilatant systems the converse situation has been observed. Furthermore, these phases are not clearly distinguishable, but to the contrary they are spatially interconnected in a complex way. The structure modeling has been made for non-Newtonian bodies using the Shklovskii-de Gennes model. The studies have found that the construction composite sand cement system is defined as the pseudoplastic body where cement and sand act as the rigid phase, water solution of polyoxyethylene – as the viscous phase. These findings can be used to prove the influence of polymer powder on the workability of dry mortar

Production and investigation of properties of sulfide composite materials based on technogenic sulfur waste with titanium chloride as an activator

The modification with titanium chloride contributes to the increase in active sites of silica-containing compounds and opening of sulfur rings. As an activator, titanium chloride helps to make resistant and durable high-performance sulfur composite materials

Measurement of the eta->pi+pi-e+e- decay branching ratio

The reaction pd->3He eta at threshold was used to provide a clean source of eta mesons for decay studies with the WASA detector at CELSIUS. The branching ratio of the decay eta->pi+pi-e+e- is measured to be (4.3+/-1.3+/-0.4)x10^-4.Comment: 10 pages,6 figures revised versio