Abstract
The article describes methods for modifying glass and basalt fibers and threads, and composite materials from them. Special attention is paid to plasma methods. Twisted glass thread and ...basalt twisted thread are investigated in the work. Plasma treatment was used to modify the threads. The type of plasma is nonequilibrium, low-temperature; the type of discharge is high-frequency capacitive. The results of research of thread properties, such as morphological changes and breaking load of threads. The plasma-treated and non-treated samples of threads were compared. The modes of plasma modification of threads in which the increase of breaking load strength of glass threads up to 23 % and of basalt threads up to 10 % is achieved have been established.
The structural, electromechanical, and dielectric properties of (1 − x)(0.8Na0.5Bi0.5TiO3-0.2BaTiO3)-xCaTiO3 (1 − x) (0.8NBT-0.2BT)-xCT ceramics are studied as candidates for room temperature ...actuators with high field-induced strain. The choice of 0.8NBT-0.2BT as a starting composition is motivated by the large tetragonality in this concentration range, even though it is located far away from the morphotropic phase boundary. CaTiO3 was chosen as a third component to decrease the depolarization temperature and achieve a high field-induced strain at room temperature. The measured strains at the field-induced phase transition are remarkably lower than might be expected from the jump in unit cell parameters at the phase transition. This inconsistency could be related to an incomplete field-induced phase transition from the ferroelectric phase to the nonpolar phase. Among all of the manufactured samples, the phase transition is close to room temperature in the composition with x = 0.100, which allows obtaining unipolar strains up to 0.23% at E = 65 kV/cm. Electrostrictive-like strain was observed not only above the depolarization temperature but also in the region of field-induced phase transition.
The article describes the methods of modification of glass fibers, threads and composite materials made of glass fibers. In the work, the twisted glass thread and electrically insulating glass tape ...were investigated. Plasma treatment was used to modify the threads. Plasma type is nonequilibrium, low temperature; type of discharge—radio-frequency capacitive. The aim of the work is to study the strength properties of yarns and tapes, before and after treatment in low-temperature plasma.The plasma modification of the threads in the argon/propane-butane and propane-butane gases medium at 4 kV has been found to increase the breaking load strength of glass threads up to 23%.The subsequent treatment of the tapes in the propane butane medium increases the strength to 5%.
This study is aimed at analyzing incoming passenger traffic using AnyLogic software at a typical underground station in order to examine it for points of congestion.
The article considers changes in the properties of Rusar-S brand aramid fiber due to the treatment of low-pressure plasma of radiofrequency capacitive discharge. After modification, there was ...recorded the growth of hydrophilicity in the environment of inert and oxidizing gases. The paper discusses the results of IR spectroscopy of Rusar-S aramid fiber before and after plasma modification. An obtained data of research can explain the influencing mechanisms of RFC discharge plasma of a low-pressure on the properties of aramid fiber.
The article studies the effect of plasma modification on the flame retardant properties of blended fabrics. The regime of plasma treatment is revealed at which effective and uniform solution ...absorption of the flame retardant composition of textile materials is achieved. It was found that the most effective fixing of the flame retardant is carried out on samples that underwent double plasma treatment before and after impregnation with the flame retardant.
This paper discusses effects of different dopants, sintering technique and parameters on microstructure and properties of pure and Yb, Er-doped Na
0.5
Bi
0.5
TiO
3
(NBT). All stoichiometric ...compositions follow the abnormal grain growth mechanism (AGG) and exhibit a bimodal grain size distribution. Bi over-stoichiometry, two step sintering and hot pressing are effective inhibitors of AGG. Microstructure of sintered NBT greatly influences such properties as dielectric permittivity and depolarization temperature.
A series of PLZT (8/65/35) ceramics with different Mn2O3 concentration (0.01, 0.1, 0.3, 1.0, and 3.0% by weight) have been synthesized to figure out its influence on their dielectric properties. The ...complex dielectric permittivity ε* = ε′−iε″ as function of frequency and temperature as well as polarisation loops P(E) have been studied as a function of Mn concentration.
It was found that Mn doping is restrained the Vogel-Fulcher law held in the unmodified PLZT compound producing essential change of the dependence of ε* on temperature and frequency and of the shape of P(E). The observed effects are explained by gradual involvement of Debye and Maxwell-Wagner polarisation mechanisms in relaxation processes with the growth of the concentration of Mn concentration admixture. A decrease of the ε'(T) maximum value and shift of the maximum to higher temperatures is observed.
The observed effects are attributed to impacts of Mn2+ and Mn3+ ions: formation of oxygen vacancies paired with Mn2+ as dipoles and Jahn-Teller distortion prompted by Mn3+ ions.
•A series of PLZT ceramics with different Mn2O3 concentration have been synthesized.•Temperature influence of the dielectric properties.•The effects of Mn concentration on dielectric properties were discussed.
—Promising areas of scientific and technological development of the Russian Federation in the field of ecology and nature management and related problems and solutions for assessing the public health ...risk are considered. The prospects of creating methods for rapid assessment of public health risks using modern data and representations of toxicokinetics and toxicodynamics of a substance are substantiated. It is shown that it is possible to deduce adequate mathematical dependences for substances regardless of their structure, based on modern concepts of the formation of the dose of a toxicant in the body from the position of toxicokinetics. To make an adequate forecast of toxicometric indicators (
LD
,
ED
) when constructing mathematical models, it is proposed to use pharmaco- and toxicokinetic parameters estimated within the normal range as independent variables (for medicinal substances not higher than their therapeutic doses, and for other substances not higher than their thresholds). Our definitions of the notions of a norm, the threshold of harmful action, and pre-pathological conditions of the body from the position of detoxification of substances are presented. The reference range of the norm for the values of the pharmaco- and toxicokinetic parameters of a substance is justified taking into account individual differences of the organism within the boundary of the standard deviation (±2δ) from the normatively established value, which does not lead to any negative (side) physiological deviations.
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