Peculiarities of educational environment at mining and metallurgical schools of the Urals

The relevancy of the issue under study stems from the contradiction between the need for a modern interpretation of the activities of mining and metallurgical schools, which had played a prominent role in the institutionalization of the vocational education environment as well as from moral “obsolescence” of research work results in this field. The goal of the article is the development of environmental indices of mining and metallurgical education of the Urals. The principal concept of research of this problem is the system approach, which allows considering the main peculiarities of the educational environment at mining and metallurgical schools of the Urals comprehensively. This article includes structurally significant characteristics of the educational environment at mining and metallurgical schools of the Urals. The contents of the article may be used for the purpose of modeling, designing and construction of an educational establishment (system) meeting the demands of the new communicational reality within the system of relations between education, industry, and social environment. © 2016 Chapaev, Erofeev and Dvořáková

Development of the recommendations on selection of glass-fiber reinforced polyurethanes for vehicle parts

© Research India Publications. Advanced polymer composites have essential features: high specific strength ratio, resistance to aggressive substances (water, fuel, oil, lubricants, weak alkalies and acids), wide operation temperature range (from -60 to +80 °C), sufficient durability (up to 10 years), high aesthetic qualities. The use of polymer composites for vehicle parts significantly reduces the curb weight of a vehicle, improves its dynamic behavior, increases its payload capacity, reduces its fuel consumption and emissions. The research was focused on the parts made of rigid glass-fiber reinforced polyurethane. The samples were made using the system based on polyol component А and isocyanate component B in a ratio of 1,75:1 (A:B). As a filler the glass fiber roving was used in the amount of 25 weight parts per 100 weight parts of the matrix component. The glass-fiber reinforced polyurethane parts were manufactured by spraying. The paper describes the comprehensive research of the glass-fiber reinforced polyurethane properties including the evaluation of thermal resistance, impact resilience, temperature resistance, Shore D hardness, acoustic absorption coefficient with the state-of-the-art test procedures and research equipment. The recommendations were developed to select glass-fiber reinforced polyurethanes for vehicle parts: for parts where the material is under high load during operation (temperature, impact resilience, etc.) it is recommended, whenever possible, to use the materials with larger thickness; for the parts where hardness is subject to special requirements – the materials with smaller thickness; during part production it is necessary to precisely carry out the operations of part manufacturing process to avoid any defects which are stress raisers and reduce the material strength

Study of effects of redispersable latex powders on hardening kinetics of cement-sand composites

Redispersable polymer powders act as boosters of the physical and mechanical properties in the cement-sand composite. For the studies the most typical redispersable polymer powders were used - Rhoximat PAV 22 and Rhoximat PAV 23 latex powders, by Rhodia. The analysis of the micrographs showed that the new formations of the cement rock had a pronounced needle-like form, and the cements with the additives were partially covered with the polymer film of the redispersable particles. The resulting polymer bridges and cords in the structure prevented growth of the cracks which were formed due to shrinkage and applied external force. Film-forming latex of redispersable powder can increase fracture energy of the cement-sand composite significantly. In view of this, of great significance is strength of the polymer itself. The higher strength polymer has, the greater force one should apply to fracture modified mixture. The basic components of Rhoximat PAV 22 and Rhoximat PAV 23 are vinyl acetate and vinyl versatate. Vinyl resins in the cement composites are known to develop a lattice which penetrates the structure formed by the cement gel, and, thus, act as an additional binder in the material

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

Mechanosensitive calcium flashes promote sustained RhoA activation during tight junction remodeling

Epithelial cell–cell junctions remodel in response to mechanical stimuli to maintain barrier function. Previously, we found that local leaks in tight junctions (TJs) are rapidly repaired by local, transient RhoA activation, termed “Rho flares,” but how Rho flares are regulated is unknown. Here, we discovered that intracellular calcium flashes and junction elongation are early events in the Rho flare pathway. Both laser-induced and naturally occurring TJ breaks lead to local calcium flashes at the site of leaks. Additionally, junction elongation induced by optogenetics increases Rho flare frequency, suggesting that Rho flares are mechanically triggered. Depletion of intracellular calcium or inhibition of mechanosensitive calcium channels (MSCs) reduces the amplitude of calcium flashes and diminishes the sustained activation of Rho flares. MSC-dependent calcium influx is necessary to maintain global barrier function by regulating reinforcement of local TJ proteins via junction contraction. In all, we uncovered a novel role for MSC-dependent calcium flashes in TJ remodeling, allowing epithelial cells to repair local leaks induced by mechanical stimuli

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

Building Heat-insulating Materials Based on the Products of the Transesterification of Polyethylene Terephthalate and Dibutyltin Dilaurate

In this paper, we offered a technological basis for production of heat-insulating polyurethane materials based on the aromatic polyester - the product of transesterification of polyethylene terephthalate and corrective additive - dibutyltin dilaurate. Also, we presented the formulation and properties of the developed polyurethanes

Study of the process e+e−→ppˉe^+e^-\to p\bar{p} in the c.m. energy range from threshold to 2 GeV with the CMD-3 detector

Using a data sample of 6.8 pb$^{-1}$ collected with the CMD-3 detector at the VEPP-2000 $e^+e^-$ collider we select about 2700 events of the $e^+e^- \to p\bar{p}$ process and measure its cross section at 12 energy ponts with about 6\% systematic uncertainty. From the angular distribution of produced nucleons we obtain the ratio $|G_{E}/G_{M}| = 1.49 \pm 0.23 \pm 0.30$

Measurement of the e+e−→K+K−π+π−e^+e^- \to K^+K^-\pi^+\pi^- cross section with the CMD-3 detector at the VEPP-2000 collider

The process $e^+e^- \to K^+K^-\pi^+\pi^-$ has been studied in the center-of-mass energy range from 1500 to 2000\,MeV using a data sample of 23 pb$^{-1}$ collected with the CMD-3 detector at the VEPP-2000 $e^+e^-$ collider. Using about 24000 selected events, the $e^+e^- \to K^+K^-\pi^+\pi^-$ cross section has been measured with a systematic uncertainty decreasing from 11.7\% at 1500-1600\,MeV to 6.1\% above 1800\,MeV. A preliminary study of $K^+K^-\pi^+\pi^-$ production dynamics has been performed

Non-Newtonian Couette-Poiseuille flow of a dilute gas

The steady state of a dilute gas enclosed between two infinite parallel plates in relative motion and under the action of a uniform body force parallel to the plates is considered. The Bhatnagar-Gross-Krook model kinetic equation is analytically solved for this Couette-Poiseuille flow to first order in the force and for arbitrary values of the Knudsen number associated with the shear rate. This allows us to investigate the influence of the external force on the non-Newtonian properties of the Couette flow. Moreover, the Couette-Poiseuille flow is analyzed when the shear-rate Knudsen number and the scaled force are of the same order and terms up to second order are retained. In this way, the transition from the bimodal temperature profile characteristic of the pure force-driven Poiseuille flow to the parabolic profile characteristic of the pure Couette flow through several intermediate stages in the Couette-Poiseuille flow are described. A critical comparison with the Navier-Stokes solution of the problem is carried out.Comment: 24 pages, 5 figures; v2: discussion on boundary conditions added; 10 additional references. Published in a special issue of the journal "Kinetic and Related Models" dedicated to the memory of Carlo Cercignan