The total content (c_s ) of similar organic compounds is usually determined without their separation by measuring their generalized spectral signals at one or more analytical wavelengths (AW). The resulted es­ timates of c_s are approximately adequate if all the sensitivity coefficients of the substances (components of the desired group) are the values of the same order of magnitude. The possibility of a correct assessment of c_s with a strongly pronounced intragroup selectivity of signals has not been previously tested. Model hexane solutions of the known composition simultaneously containing mono-, bi-, and tricyclic arenes at с_s value about 10^-4 mol/dm³ were analyzed to verify this variant of the group analysis. At a fixed wavelength, the values of molar absorptivity of arenes with different numbers of rings differ by 2 - 3 orders of magni­tude. Two variants of group analysis were compared: 1) measurement of the generalized signal of arenes at 260 nm with subsequent calculation of the result using univariate calibration in terms of naphthalene or anthracene; 2) measurement of generalized signals for several m wavelengths in the spectral region of 250 - 290 nm with subsequent calculation of the result using the inverted multivariate calibration. The first method (calculation of the integrated index) led to large systematic errors, sometimes exceeding 100 % rel. (in modulus) which appeared insensitive both to the wavelength and to the nature of the stan­dard substance. The second method provided more correct results and even at m = 11 the errors of group analysis did not exceed 10 %. Nevertheless, the errors in the estimation of c_s dramatically increased if the sample contains components (arenes) of the desired group that were not taken into account when con­structing the inverted calibration. It is shown that with a strongly pronounced intragroup selectivity of signals, group analysis can and should be carried out using inverted multivariate calibrations.

   A method of food radiation treatment can address a number of problems in the food industry, including the suppression of pathogenic microbial contamination, preservation of the nutritional value of the prod­uct, and extension of the food shelf life. When combined with a highly sensitive gas chromatography-mass spectrometry, the method provides detection of biochemical markers of radiation processing in meat prod­ucts with a low content of fat, such as chicken and turkey. We present the results of studying the depend­ ence of the content of volatile organic compounds in chilled chicken meat treated with 1 MeV accelerated electrons in a dose range from 250 Gy to 20 kGy during two weeks of storage. Concentrations of volatile organic compounds in the irradiated and control samples of food samples were determined on the zeroth, 1 st , 4 th , 6 th , 8 th , 11 th and 13 th days after irradiation. Concentrations of aldehydes, namely, hexanal, heptanal, and pentanal identified in poultry meat samples exposed to radiation demonstrated a similar behavior during two weeks of product storage. Samples exposed to irradiation in a dose range from 500 Gy to 10 kGy exhibited an increase in the aldehyde content on days 1-4 after irradiation. It is shown that the time of aldehydes accumulation in irradiated meat shifts towards a shorter period of the product storage with an increase in the dosage of irradiation. Thus, aldehydes can be considered potential markers of the radiation treatment of chicken meat during the first four days after irradiation.

   A combination of the methods of X-ray phase and X-ray spectral analyzes is used at domestic aluminum plants for operational technological control of the composition of cooled electrolytes. In this case, standard samples of chemical and phase composition are used to calibrate measuring instruments. The synthesis of standard samples from simple components is impossible due to the inadequacy of their microcrystalline structure to real electrolyte samples. Therefore, it is necessary to develop standard samples directly from the material of real electrolytes with a reliably established quantitative chemical and mineralogical phase composition. We managed to develop a set of 30 standard samples of aluminum-produced electrolyte using electrolytes taken from the electrolysis baths of various plants; some of the samples were doped with so­dium, aluminum, calcium, and magnesium fluorides to expand the range of compositions. A metrological certification of the set with the status of "Industry standard samples" was performed based on the data of interlaboratory analysis according to the methods of X-ray control used at the plants and according to the well-known Rietveld X-ray phase method for determining the quantitative phase composition. The set has been successfully implemented at seven RUSAL plants.

   The trueness and precision indicators of two methods — complexometric titration and atomic absorption spectrometry (AAS) — were evaluated to select a method that would provide a higher accuracy of copper determination in a brass coating. In the titrimetric method of copper determination, the brass coating was dissolved in a mixture of ammonia and hydrogen peroxide and titrated with a solution of Trilon В in the presence of xylenol orange indicator, whereas for the atomic absorption method the coating was dissolved in nitric acid and the test solution was measured on an atomic absorption spectrometer. Two laboratories took part in the experiment. The results of measurements and the calculated precision indicators (repeat­ability and reproducibility) for both methods are presented. The intra-laboratory (intermediate precision) and general precision of the methods was compared using the Fisher test, whereas the overall average cop­ per content was compared with the certified value of a standard brass sample in accordance with ISO 5725-6 "Accuracy (trueness and precision) of methods and measurement results. Part 6. Using precision values in practice. " It is shown that the atomic absorption method is the most accurate among two consid­ered methods for determining the mass content of copper in a brass coating, as it has acceptable indicators of precision and trueness.

   The goal of the study is to reveal the dependence of the glass transition temperature on conditions of its determination. We present the results of studying temperature fields in the samples of polymer materials by the method of dynamic mechanical analysis. Changes in the glass transition temperature of the poly­mer casting VSE-34 and the temperature profile in the polymer matrix ED-20/DAFS were analyzed. Stan­dard melting samples were used to correct the test results using the correction function. It is shown that the most significant temperature deviations are observed when measured in argon and helium media with heating rates of 1, 2, 5, and 5 K/min. The temperature distribution over the polymer casting sample is highly non-uniform. The difference between the temperature in the middle and at a distance of 1/4 from the edge of the sample equals 16°C (medium — argon, heating rate — 5 K/min). Moreover, at a heating rate of 1 K/min, abnormally low values of the glass transition index were marked. The results obtained can be used to improve the measurement procedure, reduce test duration and refine the results of tests in various gaseous media.

   Actively developing electric automobile transport assumes the creation of conductive lubricants. We pres­ent a setup designed to study the electrophysical properties of industrially produced and model plastic lubricants, as well as the samples of a similar consistency. The setup operates within the current frequency range from 0.1 to 1 kHz and includes a temperature-controlled measuring cell that allows changes in the sample thickness and temperature in the range from 20 to 120 °C. A method for determination of cur­rent-voltage characteristics with subsequent calculation of the specific electrical conductivity is proposed. The specific electrical conductivity of model plastic lubricants based on medical vaseline added with car­bon nanostructures (few-layer graphite fragments and their modified analogs) was studied using the de­veloped setup. Vaseline was used as a base model lubricant, since its rheological properties are similar to that of plastic lubricants and it does not contain any additional additives that can affect the measurement result. The electrically conductive properties of the dispersions of carbon nanostructures and their modi­fied analogs in vaseline were analyzed. It is shown that the introduction of carbon nanostructures into dielectric vaseline turns it into an electrically conductive material. The developed setup makes it possible to study the specific electrical conductivity of systems simulating plastic lubricants with a sufficient accuracy. The results obtained can be used to improve the methodology for studying the specific electrical conductivity of model and industrially produced plastic lubricants, including those with conductive additives.

   Additive technologies, namely selective laser melting (SLM), are often used in manufacturing products of critical duty. At the same time, the SLM process may be accompanied by the appearance of specific defects in the product. We present the results of radiation monitoring of aviation blanks manufactures using addi­tive technology by digital radiography. A digital detector system was used as an X-ray converter. It is shown that the methods of film radiography traditionally used for control in the case of aircraft objects are not always effective. The method of digital radiography, on the contrary, is the most adequate. Comparison of the results of digital radiography with data of traditional radiography revealed that the time spent on radiation monitoring when using an automated manipulator is significantly reduced, while the monitor­ing performance increases dramatically. The results obtained can be used to improve the methods of radia­tion monitoring of aircraft objects manufactured using additive technologies.

   The goal of the study is to elucidate the reasons for early fracture of the gear wheel teeth of a Cameron TA9000 turbocharger (1820 kW) after an operational load up to 1. 3 x 109 cycles.

   The chemical composi­tion and the microstracture of the tooth metal were studied using the methods of metallography, microhardness and optical microscopy. The microrelief of fracture surfaces of operational fractures was studied using electron scanning microscopy. Analysis of chemical composition proved the steel grade of the tooth metal (DIN 31CrMoV9) declared by the manufacturer. Visual analysis of the fragments under study re­vealed numerous cracks present on the tooth contact surfaces. The fatigue fracture origins detected on the fracture surfaces are typical of high cycle and gigacycle fatigue fracture. In the latter case, the detected fracture looks like a "fish eye" exhibiting an area of?? structural heterogeneity with inclusions and pores in the center. The fracture probably developed from the first tooth fragment to the fifth one being accom­ panied by an increase in the number of fatigue fracture origins known to be attributed to an increase in the stress amplitude. Metallographic study showed the presence of a subsurface hardened layer with a thickness of 120 - 200 pm with a defect-containing structure associated with grain-boundary precipitates (presumably, carbides (Fe, Cr)3C), which can result from violation of the modes of heat treatment of the gear wheel. Formation of brittle intergranular cracks on the contact surface and their subsequent develop­ment in the entire depth of the subsurface hardened layer appeared to be the reason for a decrease in the strength and bearing capacity of the gear teeth.

   Development of the nanomaterial science heightened the interest in studying the deformation mechanism accompanied by grain boundary sliding (GBS). However, the experimental study of GBS processes in mi­cro- and nanovolumes of metallic materials faces difficulties attributed to high localization of strains and requires the use of modern methods and tools of high-resolution electron microscopy. Therefore, the avail­able literature data refer mainly to theoretical and model studies in this area. Treatment of metal alloys with concentrated energy flows, for example, laser irradiation, can impart characteristic features to the grain boundary slip. In this regard, we performed the experimental study of the microplastic deformation of Armco iron with a single-phase ferrite structure under pulsed laser processing. To exclude the effect of phase transformations on the deformation process, only the heat-affected zone (HAZ) was studied. The temperature in HAZ was below the temperature of the first critical point and did not exceed 700°C, which made it possible to consider the total deformation an equivalent of the GBS deformation. The microstructure studies by the methods of optical and scanning electron microscopy revealed that in condi­tions of ultrafast heating and cooling during laser processing of metal, deformation occurred with the par­ticipation of the GBS mechanism. The characteristic features of GBS, i.e., the presence of stepped bound­ aries and accommodation zones, as well as the appearance of high-angle grain boundaries were observed. A technique is proposed for measuring the strain value through the GBS mechanism under an assump­tion that the strain vector components for cubic lattices are statistically equal. A statistical analysis of the measurements of the orthogonal component of the strain vector using the secant method was performed, which provided determination of the relative strain values by GBS mechanism in Armco iron within a range of 1.2-5.9%.

   The electroplastic effect (EPE) is a phenomenon which consists in a decrease in the strain resistance and enhancing of the plasticity of metals under the effect of the electric current of a sufficiently high density [1].

   The goal of the study is to compare the deformation behavior of single-phase commercially pure tita­nium Grade 4 and two-phase VT6 alloy under tension and external heating with introduction of a pulsed current.

   Current of various pulse ratio and density was supplied to the grips of the tensile testing machine from a pulse generator. To estimate the relative contribution of the electroplastic effect during passage of current to the reduction of flow stresses, the materials were also exposed to external heating. The microstructure of the samples in the sample head and in the vicinity of the fracture region in the longitu­dinal section was studied using optical microscopy. The electroplastic effect in the studied materials is manifested on the tensile curve through individual jumps in the downward flow stress at a high pulse ra­tio, whereas at a low current pulse ratio a decrease in the flow stress and strain hardening and increase in the plasticity are observed. It is shown that tension of the sample under the effect of current results in a greater decrease in the flow stresses than that observed under external heating at the same temperature for both materials. This confirms the athermal nature of the pulsed current effect. The critical density of the high pulse ratio current (q - 5000) capable of providing manifestation of the electroplastic effect is two times lower for a VT6 alloy than for pure titanium Grade 4. Under the same pulsed current modes, the flow stresses for VT6 decrease more than for Grade 4. Pulsed current of high pulse ratio caused an anomalous hardening effect in a VT6 alloy, but the physical nature of this effect requires an additional study. The pulsed current modes used in the study did not lead to any structural changes noticeable under optical magnification in the samples under tension, except for the disappearance of twins and separation of the impurity particles in Grade 4 and spheroidization of grains in VT6.