The paper proposes a new approach for the determination of synthetic food dyes (SFD) in co-presence, based on their extraction by magnetic nanoparticles, registration of reextract absorption spectra and chemometric data processing. Tartrazine (E102) and sunset yellow (E110) were determined in non-alcoholic drinks «YES! Fruit» and «Fresh Orange». Solid-phase extraction with Fe₃O₄ magnetic nanoparticles modified with polyethyleneimine was used to extract dyes from drinks. After the dyes were reextracted by an alkali solution, they were determined spectrophotometrically using the absorption spectra in the visible region. Individual detection of dyes with overlapping absorption bands was achieved applying a chemometric algorithm — projection to latent structures (PLS). To do this, a model of the dependence of absorption spectra versus the concentrations of dyes in their mixtures was preliminarily built using PLS, the optimal number of latent variables was found, and the characteristics of the model were estimated. The determination error in the test set was no more than 6 and 4% for tartrazine and sunset yellow, respectively. The content of tartrazine in the «YES! Fruit» sample was 2.19 ± 0.14 mg/L; sunset yellow — 5.2 ± 0.6 mg/L, respectively. The content of dyes in the «Fresh Orange» drink was 2.4 ± 0.2 and 8.5 ± 1.2 mg/L for tartrazine and sunset yellow, respectively. The accuracy of the determination was confirmed by the recovery test and by comparison with the results of reference method — HPLC using a gradient elution mode (acetonitrile: ammonium acetate, 0.1 mol/L). Thus, it has been shown that the combination of solid-phase extraction with magnetic nanoparticles, spectrophotometry and chemometrics provides the possibility of separate determination of SFD with overlapping absorption bands in soft drinks.

To reduce the adverse effects of cytotoxic agents used in cancer therapy on healthy tissues, antibody – drug conjugates are used, which provide targeted drug delivery to tumor tissues. An alternative to antibody-based drugs are conjugates of cytotoxic agents and targeted carriers with smaller molecule sizes, in particular, the DARPin G3 protein, which has high stability and specificity for HER2-positive cancer cells. The object of the study was a conjugate of a targeted protein specific to the HER2 receptor fused to the albumin-binding domain (DARPin G3-ABD) and the cytotoxic agent emtansine (DM1), which is currently in preclinical trials. Due to the risk of accumulation of unconjugated emtansine, which can cause untargeted toxicity, it is necessary to monitor its content. For this purpose, a simplified and affordable technique for the determination of free emtansine by HPLC has been developed, providing operational quality control of therapeutic conjugates. During sample preparation, the conjugate was coagulated in ethanol, then the supernatant was analyzed by micro column chromatography with UV detection on a ProntoSIL-120-5-C18 column under selected conditions. The proposed sample preparation allows for chromatographic analysis without using expensive columns to separate conjugate and free emtansine. The developed technique for determining the impurity of free emtansine in the composition of the therapeutic conjugate DARPin G3-ABD-DM1 has been validated by key indicators, and its metrological characteristics have been evaluated. The technique was tested in the analysis of laboratory conjugate samples: the content of free emtansine did not exceed 0.2%.

The metrological validation of forensic methods is an effective precedure for confirming the reliability of the results obtained for researching forensic objects. The lack of a regulatory framework requires a study of the validation methodology and the specifics of forensic methods. In connection with two types of controlled indicators (quantitative and qualitative), the methods are divided into two types: forensic measurement methods (FMM) and testing methods (FTM). It was shown that the validation of FMM coincides with the corresponding procedure for quantitative chemical analysis methods. The specifics of validation of forensic testing methods related to parameters (requirements for targeted use) and the organization of the experiment were considered. Specific examples of the use of blind tests in the validation procedure are given. Statistical evaluation of the reliability parameter of the test method is based on the calculation of the number of false/true results. A terminology and formulas for calculating different indicators of false/true positive/negative results of qualitative testing are presented. The possibilities of assessing the reliability limits of validation results of the FMM and FTM methods, as well as the results of measurements in comparative studies of the objects of expertise for solving identification problems are shown. The specifics of validation of forensic methods used in threshold tests have been studied in detail and shown.

Gas hydrates — crystalline compounds of water and gas (most commonly methane) that form at low temperatures and high pressures — can block flow in pipelines, posing risks to the operation of oil and gas fields. The aim of this work is to investigate the effectiveness of thermodynamic hydrate inhibitors in gas – water and gas – water – oil systems. The zones of hydrate formation and dissociation were investigated at pressures up to 200 bars and temperatures down to –40°C. The effectiveness of the inhibitors was evaluated using the isochoric method with stepwise heating; the influence of oil and gas composition on the formation of hydrate plugs was also analyzed. Thermodynamic inhibitors — methanol and monoethylene glycol (MEG) were used as hydrate formation inhibitors. Oil samples with different densities (0.78 and 0.85 g/cm³) were studied. It was found that the presence of oil reduces the hydrate formation temperature by 11°C. When 35% methanol was added to the gas – water – oil system within the studied temperature range, no hydrate formation occurred. In the case of denser oil (0.85 g/cm³), MEG showed lower efficiency compared to methanol due to poor solubility, low diffusion rate, mass transfer limitations, and other factors. The results obtained can be used to improve technologies for preventing hydrate formation during the operation of fields with complex oil and gas production.

The widespread use of ferrimagnetic materials necessitates the management and control of their functional characteristics, which can be modified by mechanical grinding in a ball mill. The aim of this study was to investigate the effect of high-energy milling on the structure and magnetic properties of ferrites. A barium hexaferrite (BaFe₁₂O₁₉) sample was analyzed using X-ray diffraction, BET, pulse magnetometry, and synchronous thermal analysis. It was found that milling leads to a decrease in the size of coherent scattering regions and an increase in microstrains in the ferrite material, which is accompanied by a decrease in its Curie temperature and saturation magnetization. Synchronous thermal analysis in a constant magnetic field showed that the temperature coordinates of the weighing step on the thermogravimetric curve can be used to estimate the size of the coherent scattering regions of the ferrimagnet. The identified patterns were formalized as regression models, allowing one to predict changes in the analyzed parameters depending on the grinding conditions. The obtained results can be used to improve the method for modifying the properties of magnetically hard ferrite materials using controlled grinding in ball mills.

Titanium-based solid solution alloys with the general composition Ti_xMo_{1 – x}C_yN_{1 – y} and a face-centered cubic (FCC) NaCl-type structure have attracted considerable attention due to their remarkable hardness, thermal and oxidation resistance, and chemical stability, making them indispensable in modern engineering, coating, and biomedical applications. The mechanical and physical behavior of these alloys is governed by their atomic-scale chemical composition, particularly by the ratio of transition metal and interstitial elements. However, despite extensive experimental and computational research, the correlation between elemental distribution and the resulting mechanical characteristics remains insufficiently understood. This limitation is largely associated with the drawbacks of conventional chemical analysis techniques, which are often destructive, lack precision at the atomic scale, and preclude repeated investigations. The present study aims to assess the potential of neutron diffraction as a precise and non-destructive method for determining the atomic composition and crystal structure of multicomponent Ti_xMo_{1 – x}C_yN_{1 – y} solid solutions. Experimental investigations confirmed that all synthesized alloys possess a NaCl-type crystal structure corresponding to the same space group as titanium carbide and nitride. Analysis of neutron diffraction data performed using the FullProf software demonstrated that titanium and molybdenum atoms occupy equivalent 4b lattice sites, while carbon and nitrogen atoms statistically substitute each other in octahedral 4a positions. The refined Rietveld parameters — including the reliability factors and lattice constant — exhibited excellent agreement between the calculated and experimental values, with deviations not exceeding 3%. These findings validate neutron diffraction as a powerful technique for accurate quantitative structural characterization of multicomponent carbides and carbonitrides. The proposed approach can be extended to other NaCl-type alloys containing heavy and light elements, offering a reliable pathway for the non-destructive evaluation and design of advanced heat- and wear-resistant materials.

The article considers the issues of increasing the strength and changing the defect structure in a layered steel composite obtained by pressure welding (forge welding) after severe plastic deformation (SPD) using the equal-channel angular pressing (ECAP) scheme. The aim of the work is to investigate the defect structure of the layered steel composite material after SPD. The layered steel composite material was obtained as a result of forge welding of eight plates of low-alloy steel 09G2S and alloyed carbon steel 40Kh with alternating layers. ECA pressing of the layered composite 09G2S + 40Kh in one pass was performed parallel to the plane of the layers at an intersection angle of the channels of 120° and a temperature of 823 K. The microstructure of the composite was examined using a JSM-7800F scanning electron microscope. The proportional limit of the material was determined based on the results of uniaxial compression tests using a Zwick/Roell-Z600 universal testing machine. X-ray diffraction analysis (XRD) of the composite was performed using a high-precision Ultima IV (Rigaku) powder X-ray diffractometer in CoKα radiation (wavelength λ = 1.790255 Å). An increase in the proportionality limit of the composite is shown, caused by grain refinement, a change in the crystal lattice parameter, and an increase in the dislocation density. Forge welding resulted in strain hardening in the intermediate layer (transitional between 09G2S and 40Kh steels) caused by grain boundary diffusion processes due to distortion of the crystal lattice. It was found that after forge welding and ECAP, the transition layer with a width of 4.3 ± 0.4 μm consists of deformed ferrite grains with an average size of 5.0 ± 0.5 μm. The transition layer contains impurities — manganese sulfide particles. ECAP affects the defectiveness of different layers of the joint differently: in the 09G2S layer and in the intermediate layer, the dislocation density increases significantly, while in the 40Kh layer, these values decrease slightly. In the intermediate layer, as a result of plastic deformation at the substructural (mesoscopic) level, the significant increase in dislocation density acts as a micromechanism for the formation of a fine-grained structure.

The paper deals with a modified notch failure assessment diagram taking into account in-plane and out-of-plane constraint parameters in terms of nonsingular T_xx- and T_zz-stresses in the fracture process zone ahead of the notch tip front. A local failure criterion based on an average maximum tangential stress in the fracture process zone has been proposed to describe notch failure assessment curves. The average maximum tangential stress is assumed to be equal to the local strength in the fracture process zone which is calculated by means of the Huber – Mises plasticity criterion taking into account nonsingular T_xx- and T_zz-stresses. To reflect the combined effect of the constraint parameters, it is proposed to use the T_z-parameter, which is a complex parameter of constraint at the notch tip front of a three-dimensional solids and reflects the constraint both perpendicular and along the notch tip front through the components of non-singular T_xx- and T_zz-stresses, respectively. It was established that there is the significant effect of the elastic stress concentration factor, out-of-plane notch tip constraints and T_z-parameter on notch failure assessment curves in the case of three-dimensional solids. Notch failure assessment curves shift along the abscissa axis as the theoretical stress concentration factor increases. Besides, notch failure assessment curves for three-dimensional solids are located between the curves corresponding to the conditions of plane stress and plane strain. In the case of an unlimited theoretical stress concentration factor, the notch failure assessment curves for a notched solid transform into the failure assessment curves for a solid with the crack.

The electroplasticity effect consists in increasing the plasticity of metals by passing high-density current pulses without noticeable heating due to the release of Joule heat. This effect is used in small and medium metallurgical processing, increasing the efficiency of such production processes as rolling, drawing, stamping, etc. The question of the physical nature of the electroplasticity effect still remains unresolved, which encourages laboratory studies on model samples. For this purpose, a hardware and software complex has been developed for studying the electroplasticity effect on wire samples stretched by dead load. Due to the large length of the samples, the installation allows for recording small deformations of the wire with high accuracy, which allows for monitoring the thermal expansion of the samples during the release of Joule heat. The tensile force is measured using an elastic element with glued strain gauges, the wire elongation during deformation is measured by the optical ruler, the profile of the pulse current passed through the sample is measured by a Hall sensor, and the voltage across the capacitor bank is monitored using a voltmeter. The digitized data are transmitted to recording equipment that allow real-time monitoring of all the necessary parameters of the experiment, such as tensile stresses and deformation of the sample, the maximum current density in the pulse, and its duration. This made it possible to speed up the experiment and improve the accuracy of measurements by eliminating the human factor. As an example, the results on the effect of pulse current parameters on the electroplasticity of M1 copper wire were obtained. It is shown that pulses of shorter duration but with higher current density lead to greater plastic deformation of wires, under the condition of equal Joule heating. Thus, the way of athermal increase of copper plasticity due to the effect of pulsed current is shown.

This paper proposes a new method for identification of technological processes with changing dynamics. This approach involves statistical analysis of dependencies between the inputs and outputs of the process. An algorithm for process modes identification is based on probabilistic latent analysis and EM algorithm. A process with changing dynamics is described using a multimodal model, which consists of a mode classifier and a block of basic mode models. For each mode, an inductive knowledge base is formed, a binary mask of mode inputs is calculated using feature selection, and a basic mode model is constructed. The mode classifier is trained to determine the boundaries of each mode. To improve forecast accuracy, this paper proposes using cyclical training of the mode classifier and the block of basic mode models. The idea of cyclic learning is to iteratively train both parts of the multimodal model, where the prediction result of one part of the multimodal model is used to train the other. The classifier learns to most accurately determine the boundaries of process modes, and each basic model learns to most accurately describe its corresponding mode. Mode is determined by mode classifier for the current state and the corresponding basic mode model is used to predict output parameters. The proposed approach was compared with popular machine learning methods using real data from a multimodal iron ore flotation process. Based on numerical simulation results using test process data, the multimodal identification model demonstrated the highest prediction accuracy.