In the development of food irradiation protocols, one of the objectives is to determine the optimal dose range for a specific product type, where pathogenic microflora are suppressed while biochemical and organoleptic properties are preserved. The exposure of various foodstuffs to ionizing radiation results in the formation of volatile organic compounds, whose content changes depending on the product’s irradiation dose. These volatile organic compounds can therefore be considered as marker compounds to describe irradiation-related processes. This work proposes a universal approach for studying the volatile compound profile in electron-beam-irradiated halibut, employing gas chromatography-mass spectrometry coupled with solid-phase microextraction. It has been shown that radiation processing significantly alters the profile of volatile compounds in halibut and leads to a dose-dependent increase in the concentration of these compounds. Among the identified volatile compounds, compounds serving as markers of radiation-induced oxidative processes were established: dimethyl disulfide, heptanal, octanal and nonanal. Additionally, compounds detected exclusively in irradiated halibut samples — 3-methylbutanal, benzene, and 1,3-bis(1,1-dimethylethyl)benzene were identified, making them potential markers for the radiation treatment of halibut. The results of multivariate statistical analysis (Principal Component Analysis, PCA, and Partial Least Squares Discriminant Analysis, PLS-DA) confirm the presence of pronounced dose-dependent changes and enable effective discrimination between irradiated and non-irradiated samples. The proposed approach for identifying marker compounds and classifying samples can be adapted to other food products and used in the development of universal methods for monitoring and optimizing radiation processing.

Due to increased state control over the production and circulation of distilled spirits, alcoholic products that do not comply with mandatory licensing, primarily beer and beer beverages are increasingly being adulterated. For their quality control the application of synchronous fluorescence scanning spectroscopy is described. Four beer samples and fifteen beer beverage samples were investigated. A double-beam spectrophotometer-fluorimeter SFF-2 «Fluoran» was used for the measurements. To optimize the parameters ensuring the highest information content of the obtained spectra with minimal time expenditure, the wavelength ranges of emission and excitation, their difference (Δλ), and instrument settings were varied during the experiments. Synchronous scanning of authentic and adulterated samples was performed in the wavelength range of 250 – 600 nm at wavelength differences between excitation and emission of Δλ = 30 and 60 nm. The synchronous scanning spectra of genuine beer and beer beverages clearly exhibit high-intensity maxima in the short-wavelength region at 280 (Δλ = 30 nm) and 275 nm (Δλ = 60 nm), as well as a distinct minimum at λ = 313 nm. The long-wavelength maximum was observed at 362 (Δλ = 30 nm) and 336 nm (Δλ = 60 nm). In the adulterated samples, the position of the long-wavelength maximum remained unchanged. Analysis of the obtained data showed that some beer beverage and beer samples exhibit characteristic responses from marker fluorescent compounds present in them. Other samples either lack such responses or show significantly lower intensity. It was also demonstrated that beer samples from the same batch but sold in different regions have very similar fluorescence characteristics. This method can be used for the rapid detection of adulterated products; however, further research is needed to accumulate a statistically significant dataset.

The article presents the results of a comparative study on the applicability of binary colorimetry versus photometry in the chemical analysis of drinking, natural, and waste waters for iron (II, III), nickel (II), and copper (II) contents. Sample preparation was identical for both methods under consideration. For digital photography of the solutions analised a mobile device under controlled conditions was used. To minimize external light interference, photography was conducted in a darkened room. An assessment of the influence of scattered light showed no significant contribution to the colorimetric measurement results. The obtained images were processed using specialized software and converted to a binary format, subsequently determining the binarization threshold, which was used as the analytical signal. It was found that the relative standard deviations of the results obtained by binary colorimetry and photometry do not exceed 0.12 and 0.06, respectively. Two-way analysis of variance revealed no statistically significant differences in the accuracy of the methods under consideration. However, their difference was demonstrated at different concentration levels of Fe, Ni, and Cu. It was established that in the concentration ranges of 0.10 – 2.00 mg/L Fe, 0.02 – 0.10 mg/L Ni, and 0.25 – 1.50 mg/L Cu, the sensitivity characteristics of binary colorimetry are predictably inferior to those of photometry. It was shown that for the colorimetric determination of Fe (II, III), Ni (II), and Cu (II) at concentration levels close to the detection limits of these ions, the analyzed water sample should be preconcentrated. The results of the conducted study indicate that binary colorimetry can be considered an accessible alternative in the absence of a photometer for the determination of Fe (II, III), Ni (II), and Cu (II) in water.

One effective method for preserving various materials is preservation in an inert gas atmosphere. The objective of this study is to investigate the corrosion wear of carbon structural steels during preservation in an inert gas atmosphere. Using local predictive models, the relationship between the volume fraction of oxygen in the protective atmosphere, the chemical composition of the alloys undergoing preservation, and the corrosion rate was analyzed. It was shown that for carbon structural steels, the corrosion rate in the protective atmosphere is practically independent of the content of chemical elements. The higher the ratio of nickel to chromium equivalents, the more susceptible the steel is to corrosion wear. During tests of S345 (09G2S) in a vacuum chamber with controlled oxygen levels, it was found that the corrosion rate increases sharply in the initial period due to the formation of oxide films, and then decreases because the resulting corrosion products block the corrosive medium’s access to the undamaged metal. The predicted corrosion rates of 09G2S steel in media containing 1 and 2% oxygen were 0.0026 and 0.0077 mm/year, respectively. A comparison of the predicted data obtained by calculation based on the chromium equivalent and the equivalent ratio showed that for structural steels, the calculation based on the chromium equivalent yields higher corrosion rates. The results obtained can be used in assessing the predicted corrosion rate of structural steels and the permissible volume fraction of oxygen in the protective gas atmosphere during preservation.

The use of modern high-speed sintering methods in the production of tungsten alloys leads to the appearance of residual stresses in the material. The objective of this work was to conduct an X-ray diffraction study of internal stresses in tungsten alloy samples with various microstructural parameters. The study focused on the role of sample surface quality and the influence of sample preparation on the results. It has been established that the reliability of X-ray diffraction data for highly absorbing tungsten alloy samples depends significantly on surface quality. Differences in diffraction patterns were assessed using the Bragg – Brentano scheme and symmetrical shooting with a parallel primary beam. It has been shown that the reproducibility of the unit cell parameter determination procedure allows for combining both optical schemes within a single study. It has been found that mechanical polishing of the tungsten alloy sample surface to a roughness of 1 μm does not provide comparable quality for X-ray diffraction studies as electrochemical polishing. The value of the residual stress component normal to the sample surface does not depend significantly on the quality of sample preparation. The results obtained can be used to improve manufacturing technologies for tungsten alloys-based products with predictable physical and mechanical properties.

Projection etching is an effective method for studying structure, offering advantages over traditional selective etching due to the «memory» effect. The purpose of this work is to investigate the dislocation structure of a GaAs(Te) single crystal grown by the Czochralski method in the [100] crystallographic direction using the projection etching method. During the experiments, the data from projection etching were compared with those from the more common selective etching in a KOH melt. For projection etching, a so-called AB etchant and a solution without AgNO₃ were used. Etching at room temperature was performed in a «drunk barrel», and at elevated temperatures (85 – 125°C) with manual stirring. The surface of the single crystal was analyzed using optical microscopy. Panoramic images of dislocation structures on GaAs wafers were obtained in a light microscope by stitching together individual frames. By representing the image as a matrix of brightness intensity values I(x, y) ranging from 0 to 255, the effect of silver nitrate on the contrast of etching pits was investigated. A classification of etching pits based on their morphology (grooves, stripes, rectangular pits) is presented. The influence of temperature on the rate of projection etching and the necessity of mechanical stirring are noted. The results obtained can be used in the implementation of the projection etching technique for analyzing the mechanisms of dislocation motion and multiplication depending on growth conditions.

This study investigated the influence of preliminary cyclic loading on the strength properties and damage characteristics of F500W steel under tension, as evaluated by acoustic emission and digital image correlation methods. The deformation dependencies of the acoustic emission and digital image correlation parameters were found to be consistent with each other, reflecting the stages of the fracture process, caused by the features of this process and characterized by the achievement of critical points on the stress-strain curve. Informative indicators of cyclic degradation were determined, including the total number of events (ΣN_AE), the average acoustic emission signal activity the b_AE-value, amplitude damage parameter D, the average rise angle (RA) and the sizes of the low- and high-deformation plastic zones (S_L and S_H). A shift in the maximum b_AE-value towards lower deformation has been detected with an increase in relative lifetime (N/N_f), associated with an earlier transition from the accumulation of small cracks to their merging. This is confirmed by a further decrease in the b_AE-value and D parameter. Preliminary cycling of F500W steel specimens to N/N_f = 0.4 and 0.6 does not significantly alter the shape of the deformation curves, and values of residual strength and fracture work. However, increasing the number of cycles to N/N_f = 0.8 causes an increase in yield strength and a decrease in tensile strength, fracture energy, and the ratio of tensile strength to yield strength. This indicates a decrease in the material’s plasticity after cyclic loading.

It is the purpose of this paper to present an analysis of experimental data obtained during the fracture of 17G1S (GOST steel grade) steel specimen with pre-applied damage (deep scratch across the width of the specimen). The loading process was monitored using a MicroScan 7600 PRO thermal imager with thermograms recorded in the areas of temperature increase, i.e., in the fracture area (the place of pre-applied damage). The increase in specimen temperature is due to thermoplastic effect in the areas of plastic deformation. The peculiarities of deformation localization were investigated using statistical characteristics, Minkowski connectivity assessment, thermal field clustering, and determination of average temperature values along the length of the specimen. Studies of thermograms obtained in the process of loading the specimen showed that during elastic deformation, local levels of elastic deformation are redistributed at the initial stage without increasing the coefficient of variation. At the stage before the occurrence of plastic deformations, the coefficient of variation decreases somewhat, i.e., the unevenness in the distribution of local elastic deformations decreases, and subsequently, with an increase in the level of plastic deformations, their localization increases in the area of pre-applied damage. Cluster analysis showed that as the load increases, the temperature field changes its character. The number of levels in which clusters are defined changes. At the same time, the number of clusters changes at each level. The statistical characteristics of the local distribution of deformations also change, as a rule, the coefficient of variation increases, the standard deviation increases too. As the load increases, the type of distribution density of local deformations changes. If in the elastic area of the specimen loading the distribution is unimodal, then in the plastic distribution area it has a more complex type — the modality of the distribution of temperatures (deformations) increases when a crack is formed — in this case the distribution is three-modal. There are distribution areas corresponding to the elastic deformation zone and two plastic deformation zones. The average distribution corresponds to the crack appearance zone, where in the fracture area the specimen has a lower temperature (a crack is formed).

The purpose of the presented work is to experimentally adjust the measuring modules of axial force monitoring gauge, taking into account their actual measurement ranges. Novosibirsk State Technical University has developed force monitoring gauge with elastic elements of two geometries: the «Flange» type and the «Collar» type. The elastic element of the «Flange» type is made of 50KHFA steel, and 36NHTU alloy was used for the geometry of the «Collar» type. Computational studies of the stress-strain state of elastic elements were carried out in the ANSYS WorkBench software package. The locations of strain gauges on elastic elements were selected according to these calculations. Compression tests of elastic elements were conducted on the basis of the static testing hall of the NSTU Research Institute of Materials and Structures. The equipment for testing was made of 30KHGSA grade steel. This equipment is placed between the grips of the Instron testing machine and allows to evenly distribute the applied compressive uniaxial load on the elastic element. At the first stage, loading tests of elastic elements with a measuring module for force control were carried out up to 110% (150%) of the upper limits of the measuring ranges of the gauge under consideration for geometries of the «Collar» type («Flange» type) accordingly. At the second stage, the elastic elements were loaded stepwise within the measurement range. The obtained data is presented in graphs illustrating the improvement in the readings of the measuring module after its training. The results can be used in further studies of elastic elements of the typical geometry of gauge for monitoring axial forces of other loading intervals.