The effect of formic acid as a mobile phase additive on the retention time of five compounds (sodium nitrite, potassium iodide, acetone, uracil, oxalic acid) selected as dead time markers was studied in reversed-phase high-performance liquid chromatography (RP HPLC). All the studied compounds were shown to have weak retention on the surface of octadecylsilica gel under neutral conditions. However, the introduction of an acidic additive to the mobile phase leads to an increase in the retention of compounds giving an alkaline reaction. This effect was particularly strong for sodium nitrite. The lowest retention time was observed for oxalic acid, and it can be recommended as a dead time marker for the analysis of weakly polar and nonpolar compounds in neutral and acidic media.

A method for determining platinum and palladium in technological solutions of refining production by inductively coupled plazma atomic emission spectrometry (ICP AES) with preconcentration on a synthetic carbon sorbent has been developed. Platinum metals content in such solutions in lower than detection limit of direct ICP-AES determination (~0,1 mg/dm³). The values of the dynamic exchange capacity (DEC) for the sorption concentration of platinum and palladium from technological solutions have been found. Depending on the type of solution for platinum, the DEC is 0.7 – 1.6 × 10^–3 mg/g, and for palladium 0.7 – 0.9 × 10^–3 mg/g. Based on the DEC values, an effective sorbent weight (155.9 g) was calculated for concentrating platinum and palladium. To concentrate platinum and palladium the test solution is passed through a column with sorbent for 4 h, then analytes are eluted with aqua regia for ICP-AES determination. The recovery of platinum at the stage of sorption concentration is 98.7 – 99.3%, and palladium 98.9 – 99.7%. The elution degree is 98.7 and 98.8%, respectively. To estimate the accuracy of the proposed technique the model solutions with different platinum metals content were also analysed by inductively coupled plasma mass spectrometry (ICP MS). The results obtained by two methods are comparable that allows to recommend sorption-atomic emission technique as a less expensive alternative to ICP MS for determination of Pt and Pd trace contents in technological solutions of refining production.

A method for determining organochlorine pesticides in snow cover using gas chromatography with an electron capture detector is proposed. The proposed method is characterized by accuracy (δ = ±14%), reproducibility (σ_R = 1%) and repeatability (σ_r = 2%). The range of determination of mass concentrations of OCPs is 0.001 – 1.000 g/cm³. The completeness of extraction for 9 OCPs varies in the range of 95 – 97%. This method was used to analyze snow cover on 13 agricultural sites in the Ufa and Sterlitamak districts. Five organochlorine pesticides were detected: β-HCH, γ-HCH, DDT, DDD and heptachlor. It was found that all the studied sites are contaminated to a greater extent with DDD. The detected OCP content at all sampling points does not exceed the MAC of organochlorine pesticides in natural waters. The obtained data show that the most polluted with organochlorine pesticides is the arable land of the APC «Alekseevsky» (Republic of Bashkortostan, Ufimsky district, Alekseyevka village). The total concentration of OCPs was 0.40 μg/dm³. The least polluted territory is the arable land of the state farm «Roshchinsky» (Republic of Bashkortostan, Sterlitamaksky district, Podlesnoye village). The total concentration of OCPs was 0.09 μg/dm³.

Crystallographic texture has a significant impact on the properties of materials, therefor the problem of texture descriptions by means of standard components is topical. The current work presents the results of texture analysis of various materials by via the component method in combination with other methods of orientation distribution function (ODF) restoration for simplification of initial guess determination. The calculations were carried out using a software, developed for the ODF restoration from incomplete direct pole figures by the means of component method. The developed software was used for the ODF restoration of the model Santa Fe texture and experimental texture of Mg – 4.5% Nd alloy sample, subjected to hot pressing. For the model texture, sets of initial approximations with one obviously false component were used. For the experimentally obtained texture, the axial components determined from the experimental data were used as an initial guess. In both cases there is a good agreement between experimental and calculated data. A method for simplifying the determination of initial restoration parameters was also proposed and tested. The results obtained using the presented method make it possible to evaluate the influence of individual components on the properties of the studied materials, and the properties modeling allows more efficient use of texture studies in the development of a technology for creating materials with desired properties.

The paper presents the results of research and mathematical modeling of the effect of biaxial mechanical loading on the magnetic characteristics of spring steel 65G. Determination of the magnetic characteristics of the steel sample included registration of the magnetic hysteresis loop, the harmonic spectrum of which was analyzed under various combinations of external load. It was found that relatively homogeneous tensile stresses act on the specimen in the area of magnetic parameters measurement. The distribution of loads along the cross-sections of the specimen shows that under uniaxial stretching along the horizontal or vertical axis the character of the stress distribution does not change, provided that there is no sharply pronounced anisotropy. It is also revealed that an increase in the external biaxial tensile load leads to a decrease in the recorded values of the coercive force. However, at uniaxial loading the coercive force value grows and sharp changes in the values of the considered harmonic components are observed (load about 50 MPa), which can speak about the processes of redistribution of internal residual stresses in the specimen. The obtained results can be used in ensuring safe operation of equipment elements made of spring steel, as well as serve as a basis for the development of a magnetic method for evaluating the acting loads of a complex type.

Bismuth-containing monodoped pyrochlores have promising photocatalytic and dielectric properties. The paper presents the results of studying the properties of multielement pyrochlore containing transition 3d-elements in equivalent amounts. Mixed oxide pyrochlore of the composition Bi₂Co_1/3Cu_1/3Ni_1/3Nb₂O_9+Δ (sp. gr. Fd-3m, a = 10.5378 ± 6 Å) was synthesized by the solid-phase reaction method. The chemical state of transition element cations in the oxide pyrochlore was estimated by X-ray photoelectron spectroscopy (XPS). The parameters of the Bi5d, Nb3d, Co2p, Ni2p, Cu2p XPS spectra for the mixed pyrochlore were compared with the parameters of transition element oxides. The content of Cu (I, II) cations was determined based on the analysis of the relative intensity of peaks in the Cu2p spectrum. It has been established that for complex pyrochlore a characteristic shift of Bi4f- and Nb3d-spectra to the region of lower energies by 0.25 and 0.65 eV, respectively, is observed. The width of the forbidden band of pyrochlore for the direct allowed most intense electronic transition is 1.1 eV. The obtained results can be used to improve the technology of manufacturing multilayer ceramic capacitors and microwave dielectric materials.

Pultruded glass-fiber composites have been widely used in road infrastructure and in construction, but their strength characteristics under complex stress state at different temperatures have not been determined, which complicates their further implementation. This work is devoted to the determination of static strength and stiffness of pultruded glass-fiber composites under normal and shear stresses (induced by simultaneous axial loading and torsion of specimens) for three different temperatures. The paper reveals methodological aspects of testing under multiaxial loading, in particular, analyzes different variants of specimen tabs. The experimental part included uniaxial tensile, torsion, compression tests, as well as multiaxial combined tensile and compression tests with torsion at normal, elevated, and low temperatures. Sensitivity of pultruded glass-fiber composites to complex stress state is revealed. The failure envelopes were built for after axial and multiaxial testing at various temperatures. The failure criterion of the fourth order is proposed. The displacement and strain fields of the tubular specimens were analyzed using the VIC 3D at the chosen loadings and temperatures. The displacement fields were similar on the surfaces of the specimens that indicates of correct and uniform loading. The characteristic fractures were presented. The cracks on the specimens were different and correspond to respective loading parameters and temperatures. The obtained data allows to predict the failure of the pultruded glass-fiber composites under complex loadings and different temperatures, which is necessary for implementation of such materials.

It is noted that the major factor characterizing process of a cyclic elastoplastic loading is the diagram of a deformation in coordinates «stress – strain». The kinds of this diagram generally depends on the level of service stresses and strains, the mode and conditions of a loading, type of constructional material. At the same time one of fundamental problems of mechanics of a deformation and fracture which solution allows to carry out formation of the basic state equations, describing conditions of achievement of limit states on the basis of criteria of accumulation of damages, is the task about establishment of regularities of a kinetics of strains at a cyclic elastoplastic deformation which directly form basic parameters of deformation criteria of low cycle fracture. On the basis of results of the executed experimental researches it is shown that at the presence in cycles of dwells on extrema of loading and superimposition on these dwells of variable stresses in comparison with a regular cyclic loading with equal amplitudes of stresses the evolution of additional strains owing to an propagation of processes of a creep takes place. These strains of a creep substantially cause growth of cyclic plastic strain in each cycle of a loading, and also stimulate increase in an elastoplastic strain from an active cyclic deformation. At the same time existence of dwells on extrema of stresses without superimposition of additional variable stresses most influences on growth of full plastic strain in cycles. Superimposition of additional variable stresses during dwells also increases values of strain of a creep, but this increase is shown more at their impact with smaller frequencies, than at their dynamic application. The factor of increase in cyclic plastic strain at forms of a cycle with dwells and superimposition at their course of additional variable stresses causes decrease in these cases of a low cycle fatigue life in comparison with a regular loading without dwells, equal on amplitudes of stresses, and that more than values of strain from a static and dynamic creep are higher. Growth of cyclic plastic strain due to the additional plastic strain of a creep progressing during dwells according to deformation kinetic criteria increases damageability of material in the course of a cyclic elastoplastic deformation that causes decrease in a cyclic fatigue life.

The article deals with the method of instrumental indentation as an effective tool for studying the mechanical properties of thermoplastics. The method allows to determine such material properties as hardness, modulus of elasticity, rheological characteristics. The paper presents a review of examples of using the method of instrumental indentation to solve research problems in studying the properties of various types of polymeric materials, describing the parameters that affect the results of measurements. Analyses and experimental studies of the method’s capabilities were carried out on the example of high-density polyethylene, which is used in the production of gas pipelines. The results showed the applicability of this method in studying the material properties of polyethylene (PE) gas pipeline pipes for diagnosing their technical condition. In this work, samples that have been in service for a long time and a sample of new pipe were investigated. It has been revealed that the hardness values of polyethylene samples of different service life as an indicator of resistance to plastic deformation under static loads are quite close, while the rheological properties differ significantly. This peculiarity should be taken into account when conducting various mechanical tests, since the rate of load increase during such tests will significantly affect their results. It was found that the values of hardness and modulus of elasticity decrease with increasing indenter dwell time under load due to stress relaxation in the deformed region under the indenter. The influence of polyethylene structure on its mechanical properties is considered. It is also revealed that the modulus of elasticity of polyethylene samples multiply increases when the degree of crystallinity changes from 48 to 56%. The article describes the prospectivity and efficiency of using the method of instrumental indentation to analyse the elastic-plastic and rheological properties of thermoplastics, as well as their relationship with the crystal structure.

In this paper, for the intelligent analysis of textual, numerical and graphical empirical data in various subject areas, a method of Automated system-cognitive analysis and its software tools — the intelligent Eidos system is proposed. A brief description of this method and tools is provided, which practically automate empirical cognition by many orders of magnitude increasing the possibilities of natural intelligence and are developed in a universal formulation, independent of the subject area and the specific task being solved. The specificity of this method is that independent and dependent variables can be formalized both in textual scales (logical, nominal (categorical linguistic variables) and ordinal) and in numerical scales in various units of measurement. At the same time, the method and tools ensure comparability of processing data of different types presented in different types of scales and in different units of measurement by metrizing text scales, i.e., increasing their degree of formalization to the level of numerical scales. This is achieved by calculating the amount of information or other quantitative measures of knowledge contained in the gradations of descriptive scales about the transition of the modeling object to the states described by the gradations of classification scales. The paper sets numerous tasks that can not only be solved using this method and tools, but are also stages of achieving the goal through Automated system-cognitive analysis of the modeling object. Task-1: cognitive structuring of the subject area, static and dynamic interpretation of classification and descriptive scales and gradations; Task-2: formalization of the subject area; Task-3: synthesis of statistical and system-cognitive models, multiparametric typing and particular criteria of knowledge; Task-4: verification of models; Task-5: selection of the most reliable model; Task-6: system identification and forecasting, integral criteria of knowledge; Task-7: decision support in simplified and developed versions; Task-8: the study of a modeling object by examining its model includes more than 10 subtasks.