Radiation treatment of food products carried out to increase their shelf life can result in chemical transformations initiated by free radicals. Volatile compounds (alcohols, aldehydes, ketones, etc.) formed, in particular, as a result of lipid oxidation, impair the organoleptic properties of products. Method of gas chromatography-mass spectrometry (GC-MS) makes it possible to identify the fact of food processing by detection of volatile marker compounds: in the case of meat products, the existing standard brings under regulation detection of 2-alkylcyclobutanones, however, the products with a reduced fat content, such as turkey and chicken, require an alternative marker. The results of GKh-MS study revealed the dependence of microbiological parameters and the content of various volatile organic substances in chilled turkey meat on the dose of electron radiation. It is shown that the total amount of alcohols, ketones and aldehydes (11 compounds) decreases exponentially with an increase in the absorbed dose. An increase in the radiation dose leads to a higher content of carbonyl compounds (aldehydes and acetone), which results in a specific taste and smell of the irradiated products. At the same time, the acetone concentration increases linearly with the absorbed dose, which makes it possible to use acetone as a potential marker of the degree of irradiation of low-fat meat products. Irradiation in the «working» doses (0.5 – 1 kGy) significantly suppresses the pathogenic microflora and keeps the organoleptic properties of the product.

A method for the determination of the glass composition in the systems PbO – SiO₂ and K₂O – PbO – SiO₂ with different additives present both in historical and modern art glass is considered. Development of a non-destructive method for determining the glass composition in conditions of museum storage is an important goal for museum practice. We propose a method for determining the composition of those glasses using a portable X-ray fluorescence analyzer (XRF). To select the optimal software suitable for measurements, we have synthesized a number of standard glass samples with the composition determined by ICP-AES. A glass sample of was dissolved in an autoclave in a mixture of nitric, hydrofluoric, and perchloric acids. The lead content in standard samples was simultaneously determined gravimetrically after fusion of the sample with sodium carbonate. Using XRF measurements of standard samples we development of a method for determination of the glass composition with an accuracy sufficient to assign the glass to one of the groups of historical glasses. The results obtained can be used for attribution of lead glass products. The content of potassium oxide in historical samples was estimated by XRF method using two independent programs with subsequent averaging of the data obtained. When using our method, the error of potassium, silicon and lead determination does not exceed 10%, which is sufficient for a museum description and attribution of an item. The developed procedure was tested in analysis of the items from the collection of the State Museum of Ceramics («Kuskovo Estate of the 18th century»).

A method for the analysis of iron ore raw materials (IORM) using inductively coupled plasma atomic- emission spectrometry (ICP-AES) and Concentration Ratio Calibration (CRC) has been developed. However, the general eq. for calibration by concentration ratios used in analysis of metals and alloys was modified with allowance for the IORM characteristics: all the elements, except sulfur, were represented as oxides, iron was represented as FeO and Fe₂O₃, and the total of 100% included ignition losses (LOI). A variant of solving the equation is proposed, which allowed us to relate the relative concentrations of the components (the ratios of the mass fraction of the determined components to the mass fraction of iron oxide) to the ratio of the line intensities of the certain element and iron line measured on a spectrometer. The equation takes into account the content of FeO and LOI, which are determined by standard methods of analysis. A method for acid decomposition of the samples in autoclaves heated in a HotBlock 200 system is proposed: a sample weight of 0.25 g was decomposed in closed vessels at a temperature of 150 – 180°C in the mixture of HCl, HF and HNO₃. The following components were determined in concentrates and pellets: Fe₂O₃, Fe_tot, Al₂O₃, CaO, Cr₂O₃, K₂O, MgO, MnO, Na₂O, P₂O₅, SiO₂, TiO₂, Co, Cu, Mo, Ni, Pb, S, V, Zn. The correctness of the developed method is confirmed by the analysis of SS of iron ore and iron concentrates, as well as by comparison with the results obtained by standardized methods. The proposed technique provides iron determination in iron ore raw materials with an accuracy no worse than that specified in GOST 23581, all other components are determined in a wider range of contents and with a higher accuracy.

An increase in the strength of steels is associated with a decrease in the content of impurities, which have a negative effect on the mechanical properties of steels. One of those impurities is hydrogen. It is known that at ultrahigh frequencies, due to the peculiarities of the distribution of alternating current over the cross section of a metal conductor, the conductivity is carried out by a thin surface layer (skin-effect). We present the results of using high-frequency currents for determination of the hydrogen content in a metal. The absorption of hydrogen by thin subsurface layers of steel is determined proceeding from a change in the voltage drop across the samples which depends on the resistance of the layers. The voltage drop as a function of the alternating current frequency is measured using a high-frequency generator, an HF-voltmeter, and an HF-galvanometer. Wire samples made of high-quality U8A carbon steel were used during testing procedure. At the same time, the amount of hydrogen absorbed by the steel was determined by the method of anodic dissolution. It is shown that the cathode-introduced hydrogen is unevenly distributed over the cross section of the sample. During the aging of cathodic hydrogenated steels of a U8A type, hydrogen diffusion from steels into the air takes place with an insignificant penetration of hydrogen into the deeper metal layers. Moreover, the hydrogen content and the resistance of the subsurface layers of the material increase with an increase in the current density during cathodic polarization. The results obtained can be used in nondestructive testing of the degree of hydrogenation of ferromagnetic products.

The capabilities of the numerical simulation of technological processes are limited by the accuracy and efficiency of determining the properties of materials which continuously change with repeated heating and cooling. The parameters of structural transformations are the principal factors affecting the properties of alloyed steels. We present a method for determining the parameters of formulas describing C-shaped curves of experimental diagrams of isothermal decomposition of austenite. The proposed approach makes it possible to reconstruct the entire C-shaped curve using a relatively small fragment near the «nose» (by three points). Joint processing of a series of curves provided determination of the parameters of ferritic, pearlitic and bainitic transformation kinetics. However, it is important to take into account the features of the diffusion decomposition of austenite. For example, ferrite and pearlite are formed in overlapping temperature ranges and have similar mechanical properties, but their combining into a single ferrite-pearlite structure complicates the construction of a mathematical model of transformation. The bainitic transformation has a transient character from diffusion to diffusionless one. As for the transformation temperature range, the limiting degree is a function of temperature (as in the case of martensitic transformation). It was shown that for ferrite-pearlite transformation the best results are obtained by the Kolmogorov – Avrami equation, and for the bainitic one — by the Austin – Rickett equation modified with allowance for an incomplete transformation.

Stress corrosion cracking is one of the most dangerous types of corrosion damage in metallic materials. We present the results of studying the impact of environmental factors on the susceptibility of AMg6 aluminum alloy and 12Kh18N10T stainless steel to stress corrosion cracking under four-point bending. Tests of loaded samples were carried out in laboratory and field conditions of the moderately warm climate of the coastal zone over a period of six months. The samples were examined daily with fixation of the time to their destruction and upon completion of the tests the appearance of the samples and the depth of intergranular corrosion on microsections were assessed. A 3D relief was constructed using macro photography of the surface with the determination of the depth of corrosion foci. We also carried out a comparative analysis of the frequency of stress-induced destruction of steel samples of various grades both in atmospheric and laboratory conditions. It is shown that in atmospheric conditions characterized by the presence of dust particles acting as concentrators for the formation of corrosion foci, the aggressiveness of the corrosive effect of the environment increases, whereas the general corrosion resistance of materials decreases. The most pronounced effect of the environment was recorded in AMg6 alloy samples when exposed under a ventilated canopy in conditions of periodic spraying of seawater aerosols. The depth of surface corrosion damage was up to 0.1 mm. When the test samples were exposed under other conditions (salt fog chamber and louvered storage) the corrosion damage was absent. The results obtained can be used to predict the corrosion resistance of the products made of AMG6 alloy and 12Kh18N10T steel when operated in conditions of loading under the impact of environmental factors.

Active and promising hydrocarbon deposits, including those on the sea shelf, are often characterized by an increased content of corrosive carbon dioxide and hydrogen sulfide. Corrosive gases present in the produced crude is a serious threat to the safety and reliability of the equipment and pipelines operating at gas production facilities. We present the results of assessing the dependence of the steel corrosion rate in the presence of CO₂ on the salinity and temperature. The experimental data were processed using the methods of mathematical statistics. It is shown that the obtained dependences provide calculation of the corrosion rate with a high degree of reliability. The impact of each factor (salinity and temperature) on the steel corrosion rate was evaluated separately. The results obtained can be used to control and predict the danger of corrosion destruction of the infrastructure facilities of oil – gas fields.

Scientific and methodological aspects of ensuring the safety of offshore subsea pipelines proceeding from the accident risk criteria are considered. A conceptual approach to assessing the defect hazard by risk criteria is formulated. This approach is based on the provisions of modern norms and requirements for the calculation of pipelines. A probabilistic model for assessing the risk of accidents at offshore subsea pipelines is developed with allowance for a random nature of defects and damage from accidents. The criterion conditions for the admissibility of defects in pipelines are formulated. Two conceptual directions for developing a methodological base for calculation of the permissible defects by risk criteria are thus proposed. The first direction is the development of semi-probabilistic calculation procedures using differentiated safety factors, with allowance for the level of the accident risk. The second direction consists in solving the problem of the probability of the pipeline destruction taking into account the restrictions in the form of a given risk value. The probability and scale of accidents are linked by a risk matrix. The calculation methodology was developed using a semi-probabilistic concept for the most typical defects in subsea pipelines. The suitability of the pipeline for operation after in-line diagnostics is determined using a three-level assessment of the permissible size of defects. The first, basic level, determines the permissible size of defects according to the strength criteria for the pipelines exposed to the action of the main loads, i.e., internal overpressure and hydrostatic external pressure. The second, extended level, determines the permissible dimensions of defects based on the strength criteria, taking into account the impact of additional longitudinal and bending loads on pipelines. The third, special level, determines the permissible dimensions of cracks and crack-like defects according to the characteristics of the crack resistance of the pipeline metal. The novelty of the methodology consists in the justification of the safety factors through the levels of failure probabilities corresponding to a given class of damage and losses. A scheme for making decisions on the admissibility of defects by risk criteria has been developed. An example of hazard assessment of defects in subsea pipelines is presented.

Magnetic and magnetoelastic methods of stress control are based on changes in the magnetic parameters of steel upon deformation. However, the magnetic properties of different steel grades, and even of the same grade in different heats may differ noticeably. The inhomogeneity of the magnetic and magnetoelastic properties of steel attributed to variations in the chemical composition, as well as in the modes of rolling and heating during manufacture affects the accuracy of stress control being a common disadvantage of magnetoelastic methods used for monitoring the stress-strain state of steel structures. The goal of the study is to consider the possibility of monitoring uniaxial mechanical stresses in steel structures in the «magnetoelastic memory» mode, based on H(σ) dependence of the strength of magnetic field of scattering local remanent magnetization of steel on the uniaxial stresses. The exponential function is shown to provide a satisfactory description of the experimental dependence of the strength of the magnetic field of scattering of the permanently magnetized 17G1S and 15KhSND steels on the stresses induced in steels by tension, compression, and impact. To improve the accuracy of the control, we propose to introduce the magnetoelastic sensitivity of steel (MSS) into the accepted form of the exponential dependence H(σ). A way to MSS determination not only on laboratory samples under ideal conditions, but directly on the construction under control (which reduces the errors of the control attributed to variations in the magnetic and magnetoelastic properties of steels) is considered. To implement the proposed procedure, prototypes of the devices for static and dynamic local loading of metal structure elements have been developed and manufactured. The devices have undergone a pilot test when monitoring the stress-strain state of the load-bearing beams of an automobile overpass. Using the developed devices, a local dosed loading with a hemispherical indenter was carried out through shock or static loading of a pre-magnetized region of the structure resulted in a decrease in the intensity of the magnetic field of scattering. A procedure for monitoring uniaxial stresses in steel structure elements by the method of magnetoelastic «memory» is proposed taking into account the measured magnetoelastic sensitivity of their material.

Development of new composite materials with a given set of properties including a high wear resistance in conditions of abrasive and shock-abrasive wear, hardness, corrosion resistance, damping properties, low cost and manufacturability of the material is an important condition for further progress of the oil and gas, mining, road construction and other industries. A distinctive feature of impact-abrasive wear is the impact interaction of parts resulting in deformation of micro-volumes or chipping, which leads to intensive destruction of the surface layer of the parts. Parts subject to impact-abrasive wear must offer a combination of properties, such as hardness, viscosity, and impact strength, which can be achieved by alloying, for example, nickel, chromium, and other ligatures, as well as by mechanical or chemical-thermal surface hardening. The intensity of impact-abrasive wear is also related to the energy and kinematic parameters of the impact. Data indicate that parts subject to this type of wear should offer a sufficient level of damping properties. However, increase of the damping properties of most materials reduces their strength characteristics, and therefore one of the effective ways to increase the impact and abrasive wear resistance is to use multilayer powder materials, i.e., a «wear-resistant steel-elastic-dissipative substrate». We present the developed installation for studying the elastic and damping characteristics of powder materials with an elastic-dissipative substrate. The design of the installation, the principle of operation, as well as the methods of testing and calculation of the characteristics taken into account when developing and studying the materials exposed to shock loads are presented. The effect of structural and geometric parameters of an elastic-dissipative substrate on the damping coefficient, attenuation decrement, and relative stiffness of the products made of powder materials is considered. It is shown that the use of elastic-dissipative substrates can increase the wear resistance of powder and compact materials to shock-abrasive wear by 5 – 6 times due to the absorption and dispersion of the impact energy acting on them. The developed installation, test procedure, and method for reducing wear can be used in testing composite and multilayer materials for impact and abrasive wear.

A method for diagnosing microinclusions in the objects of soil and geological origin is developed on the basis of the Atlas of microinclusions in soils (hereinafter referred to as the Atlas). The validation procedure and an example of the practical application of the developed technique are considered. A review of the content and structure of the Atlas, which contains 37 types of microinclusions is presented. Diagnosis of microinclusions is carried out using the Atlas key which is a sequence of identifying diagnostic features (transparency, shape, color, gloss, fracture, structure, as well as density, magnetic properties, hardness, brittleness) for different types of microinclusions. A scheme for determining the nature of a microinclusion (red brick) using the Atlas key is given as an example. The validation procedure of this method consists in experimental verification of the reliability of testing and evaluation of the reproducibility of test results under different conditions: when examining samples of various complexity by several performers at different times using different stereo microscopes. We used 17 soil samples that were previously (2 – 8 years ago) tested and stored as control samples in a laboratory collection of site-collected samples. One part of the samples was examined in usual forensic soil examinations, the other was studied in the framework of participation in the procedure of interlaboratory proficiency testing under the ENFSI (European Network of Forensic Science Institutions). Two experts performed independent studies of control samples at different times. It is shown that the composition of the complex of microinclusions (by type and number) in each of the studied samples coincides with the composition of the corresponding control sample. The experts performed 108 tests, and there were no erroneous results which indicates the reproducibility of the test results and the competence of the experts. An example of the practical application of the developed technique is given.