Polysiloxane modified with groups of rubeanic acid (dithiooxamidated polysiloxane (DTOAP)) is proposed for extraction of palladium (II) from the solution against the background of the accompanying components. Sorbent was synthesized for the first time at the Institute of Organic Synthesis (Ural Branch of the Russian Academy of Sciences) using «sol-gel» technique. Sorption of palladium (II) was carried out under competitive conditions with 9 possible accompanying metals ions present. Palladium (II) is quantitatively and selectively recovered under static conditions with DTOAP from a solution containing transition metal ions, including platinum (IV). It takes 30 minutes for complete extraction of palladium (II). Reversible character of palladium (II) sorption is shown. Quantitative desorption of metal ion from the sorbent surface is possible using a 1% solution of thiourea in 1 M hydrochloric acid. Sorption under dynamic conditions provides separation of palladium (II) from platinum (IV) and concomitant ions of base metals. DTOAP provides quantitative extraction of palladium (II) in an amount up to 0.2 mmol/g. The developed method of the atomic-absorption determination of palladium (II) with a preliminary concentration on a modified polysiloxane was tested in analysis of model and industrial solutions with a high saline background.

The study considers the possibility to use a digital camera with further computer processing of colorimetric characteristics of the image with the aim to measure kaolin turbidity of water. The calculations are made using a modified Jackson turbidimeter. It is showed that the contrast of the photographic picture of the adjustor is a suitable colorimetric function of the turbidity in the RGB color space. The interference of yellow coloring of water samples is smoothed when turbidity is measured on the green channel. The relation of the given contrast (degree of turbidity) and suspended particles concentration is determined. By its form, the relation is similar to the law of light absorbance. The rule of additivity of turbidities of the mixed solutions is determined by the method of multiple standard additions of kaolin suspension to tap water sample.

A chelating sorbent based on a copolymer of maleic anhydride with styrene containing fragments of p-aminobenzoic acid is synthesized. The sorption and complexing properties of the modified sorbent relative to thorium (IV) are studied and the main quantitative characteristics of metal ion sorption are determined. An isotherm of thorium sorption with the synthesized sorbent is constructed and optimal concentration conditions (pH = 4; V = 20 ml; msorb = 0.05 g) are specified. Calculate value of the sorption capacity is 853 mg/g (CTh = 8 Ч 10–3 mol/liter). The effect of various mineral acids (HClO4, H2SO4, HNO3, HCl) on desorption of thorium (IV) in static and dynamic conditions is studied. The maximum desorption of thorium (IV) occurs in nitric acid. The degree of extraction of thorium (IV) ions under optimal conditions exceeds 92%. A technique of sorption-photometric determination of thorium (IV) in seawater is developed.
 

We developed a self configuring genetic algorithm to quantify phase concentrations in a crystalline sample from powder X-ray diffraction data. The algorithm does not require the fine-tuning of parameters, which is inherent to most evolutionary algorithms. The software executing the algorithm uses parallel computing and allows performing reference-free quantitative phase analysis on a personal computer, a computing cluster or with the help of a computer network. The suggested method was tested on a set of trial samples with known composition. It was demonstrated that one may use data on the chemical composition of a sample to increase the accuracy of quantitative phase analysis.

Titanium alloys are widely utilized for structural applications in aerospace, automotive, military, sport equipment and chemical engineering due to their high specific strength, excellent corrosion resistance and stable moderate temperature properties. In this work, samples from titanium alloys exposed to laboratory air at 625°C for 1000 h, which resulted in the formation of an oxide scale and a layer with higher oxygen concentration. The depth of oxygen-enriched layer after annealing was estimated by four methods: metallographic examination, fractography, hardness testing and XRD analysis. This paper summarizes an effort to estimate depth of oxygen-enriched layer in titanium alloys after elevated temperature exposure.

We present the results of studying features of separating phases of acicular (lamellar) morphology in the structure of blade material of operating gas turbine engines (GTD). A decrease in the strength characteristics and plasticity of the blade feather material in the zone of phase separation which contributes to in-service fatigue destruction of the turbine blade is revealed and illustrated with a specific example. Separation of the phases of needle (lamellar) morphology can be considered a criterion for the quality control of the structure and performance of the turbine blade material which requires appropriate rating. Difficulties in revealing the identification differences in the topologically close-packed (TCP) phases and carbides of Me6C type with acicular (lamellar) morphology are noted. A tend of a heat-resistant alloy to form σ-phase (i.e., the serviceability of the alloy) can be estimated in calculation of the chemical composition from the number of electron vacancies. At the same time, detection and rejection of the blades with inadmissible discharge of σ-phases can be done methods of direct non-destructive control. We develop a method of non-destructive electromagnetic control of TCP-phase (of σ-type) present in the structure of the material of highly oxidized blades (also with extraneous ferromagnetic particles present in internal cavities. Timely detection of σ-phases present in the structure of blade materials upon manufacture or repair will eliminate using the blades with reduced strength and plastic characteristics in GTE.

Duration of growth of the fatigue crack of various steels such as AISI 4030, 40X, 40 at external excitation of various character is investigated. It should be noted that kinetics of the crack growth depends on the nature of variable loading in many respects. Experimental data of kinetics of fatigue cracks’ growth of the wide spectrum of block and random loadings of investigated steels are received and an approach for cracks’ growth estimate depending on material properties and the nature of variable external input is offered. It is shown that the duration of growth of the fatigue crack on the middle-amplitude segment of its growth depends on the completeness (irregularity) of block or accidental loading. It is offered the dependence of the longevity evaluation of fatigue crack durability from a given target size to its critical value corresponding to the moment of material destruction. For this calculation it was used the value of the fatigue crack growth duration was used at a zero regular loading with the maximum load corresponding to the maximum load of the later used block or accidental loading, also the fatigue properties of the material determined from the slope of the endurance curve under soft symmetrical loading were taken into account. The second approach is related to the application of averaged parameters of the fatigue crack growth kinetics — the slope of curve of the kinetic fatigue fracture diagram (KFFD) at regular cyclic loading with the same force parameters. The linear principle of summation of crack growth without interaction of amplitudes was used in both cases. For the study the accepted assumptions it was made a calculation of the duration growth of cracks in the program of summation the crack growth for each loading cycle (cycle-by-cycle) without taking into account the interaction of load amplitudes.

The goal of the study is to consider the impact of the structure and nonmetallic inclusions on the initiation and development of corrosion damage, as well as to analyze the mechanical properties of wheel steel in various environmental conditions to develop the effective methods providing increase in the corrosion resistance and protection of railway wheels against corrosion damage. Ensuring of the high quality of the railway wheels, their reliability and durability requires a comprehensive analysis of the mechanisms of the structure formation and changes in properties of wheel materials, not only at the stage of their manufacturing, but also during their storage, transportation and operation under various conditions. This requires a systematic approach to the study of the properties of wheel steel along with a complex of environmental parameters. The solid-rolled railway wheel has a complex design and the microstructure of the steel differs for various elements, in addition to the microstructural changes attributed to in-service wear of the rolling surface, stresses in different elements, and environmental impact. The composition and structure of wheel steel are one of the important factors determining the corrosion processes occurring in the surface layers of railway wheels. To describe those processes we carried out metallographic study of the material of solid-rolled wheels and tests for corrosion cracking and low cycle fatigue. Analysis of the mechanisms of formation and changes in the structure and properties of the material of solid-rolled wheels during their storage, transportation and operation under different conditions is carried out for the first time. New aspects of the impact of nonmetallic inclusions on the formation of corrosion damage are considered. The coefficients of environmental impact which present the degree of influence of nonmetallic inclusions on the low-cycle durability of steel are determined for the first time. Test for the susceptibility of wheel steel to stress-corrosion cracking were carried out.

The purpose of this publication is analysis of the stress-strain state in the console system «film – substrate». Deformations of the cantilever system «film – substrate» under the impact of stresses occurring upon film deposition are analyzed in beam approximation. General formulas are derived to calculate the angular and linear deformation of the system at various values of the module of elasticity of the materials of the substrate and film. In contrast to the well-known Stoney formula, the expression obtained in this paper for the angular deformation of the cantilever system is valid for different values of the film and substrate thickness. The Stoney formula is the limiting case of the derived general formula valid when the thickness of the film is several orders of magnitude less than the substrate thickness. The influence of various elastic moduli on the angular and linear deformation of the console, as well as on the stress distribution in the «film – substrate» system, is estimated. It is shown that if the substrate thickness is 100 times larger than the film thickness, the angular deformation changes approximately by a factor of two at 2-fold change in the ratio the moduli of elasticity. The measuring capabilities of the cantilever converter of stresses in the film into the angular deformation of the end of the console are analyzed. The sensitivity of the converter is estimated as a function of the ratio of film and substrate thicknesses. It is shown that the obtained expressions for the displacements and stresses can be used in studying temperature deformations and stresses in the «film – substrate» system. To do this, the stress in the film should be replaced by the product of the modulus of elasticity and the temperature change and the difference in the coefficients of thermal expansion of the materials of the film and substrate.

Coefficients of correlation and determination are widely used in statistical analysis of data. Some of the errors attributed to their use are considered in this article. We confine ourselves to the case of two variables. The linear Pearson correlation coefficient and nonparametric rank coefficients of Spearman and Kendall are used most commonly. According to the theory of measurements, the Pearson correlation coefficient can be applied to variables measured in the interval scale (and in scales with a narrower group of permissible transformations, for example, in the ratio scale) but it cannot be used in analysis of ordinal data. Spearman and Kendall’s nonparametric rank coefficients are designed to evaluate the relationship of ordinal variables. They can also be used in scales with a narrower group of permissible transformations, for example, in the scales of intervals or ratios. The critical value in testing the significance of the difference in the correlation coefficient from zero depends on the sample size and approaches zero as the sample size grows. Therefore, the use of the «Cheddock scale» is incorrect. When using a passive experiment, the correlation coefficients can be reasonably used only for forecasting, but not for control. To obtain the statistical models valid for control, an active experiment is required. S. N. Bernshtein has shown that the effect of outliers on the Pearson correlation coefficient is very large. The effect of «inflation» of the correlation coefficient is that with increasing number of analyzed sets of predictors, the maximum of the corresponding correlation coefficients, the quality of approximation, increases noticeably. A common mistake is to use the determination coefficient to estimate the quality of the least-squares recovery.

In the modeling of technical, economic, social systems, it is often necessary to solve equations with interval-specific parameters (interval equations). The solution of such equations requires special methods that differ from the methods for solving ordinary deterministic equations. A new method for solving interval equations based on the apparatus of interval mathematics is proposed. The aim of the study is to develop a completely formalized method for solving interval equations based on the mathematical apparatus thus mentioned. The method consists in using equivalent transformations of the both parts of the interval equation according to the laws of interval mathematics that allow one to move from the interval equation to the ordinary deterministic equations and their subsequent solution using known methods. It is shown that various interval equations can be solved using two different methods: multiple and interval methods. The differences between these two methods are revealed in the concept of solving the equation, in the mathematical apparatus thus used, in the possibility of exact solution, in the power of the resulting set of solutions. An example of solving the interval equation used in calculation of the contamination zone with a dangerous substance by two aforementioned methods is given. We develop a new approach to solving interval equations based on an equivalent transformation of the equation according to the laws of interval mathematics. Such a transformation allowed us to bring the equation to a deterministic form which makes it possible to solve it by well-known methods of solving ordinary (deterministic) equations. The developed approach provides the exact solution of the interval equation or its approximate solution (in the absence of exact solution).