This review discusses current applications of high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS ETAAS) for quantitative analysis. Analytical approaches for samples of various compositions are considered, including environmental objects, food products, plant and biological materials, metal-containing samples, crude oil and petroleum products, and cosmetics. The following methodological solutions are presented in order to achieve low detection and determination limits: the use of various modifiers, optimisation of graphite furnace heating programms, preliminary extraction and concentration procedures. The differences between simultaneous multielement determination and sequential determination within a single aliquot are highlighted. An analysis of the regulatory framework is provided, covering current standards for HR-CS ETAAS methods and certified procedures included in the Federal Information Fund for Ensuring the Uniformity of Measurements. The review demonstrates that CS ETAAS is a highly sensitive, accurate, and cost-effective analytical tool, remaining competitive among modern spectrometric techniques and its further development is linked to the expansion of multielement analytical methodologies for complex matrices.

The photometric method is cost-effective and easy to use, and the results of silicon determination using this method are highly reproducible. At the same time, it is more difficult to take into account the effect of the matrix on the results of photometric determination of silicon with the molybdenum blue reagent than for the determination by the ICP AES method. The procedures of GOST 12346–78 for steels and GOST 2642.3–2014 for refractory materials were tested for photometric determination of silicon in samples of complex variable composition. A universal method of sample preparation is proposed for the decomposition of samples of various compositions — catalysts based on aluminum oxide, ore, and functional composite materials. It is shown that the developed combined technique is suitable for all analyzed materials with different silicon content. The addition of EDTA during the dissolution of the melt makes it possible to mask impurities affecting the photometric determination of silicon due to the formation of strong EDTA complexes. The results of the determination of silicon in these samples obtained by the photometric method agree with the results of the ICP AES method within an error of 5%. It is noted that the results of photometric determination of silicon in ore materials are characterized by lower precision (s_r ≥ 0.09), which is associated with the complex variable composition of these samples. At the same time, the precision of the results of silicon determination in other materials by this method is higher than those obtained by the ICP AES method.

Dairy products are frequently adulterated with non-dairy fats, including beef fat. Traditional methods for authenticating milk fat are based on the analysis of fatty acid, sterol, and triglyceride compositions. This study presents a novel approach using isotope mass spectrometry, based on the difference in carbon isotope ratios between cow’s milk fat and adipose tissue. The method involves the preparation of fatty acid methyl esters (FAMEs) via alkaline treatment, followed by their separation using gas chromatography, burning in the element analyser, and detection by an isotope mass spectrometer. It is shown that sample preparation has no significant effect on the carbon isotopic characteristics of FAMEs. The differences in δ¹³C values between methyl esters of stearic and palmitic acids (δ¹³C_C18:0 – δ¹³C_C14:0) and stearic and myristic acids (δ¹³C_C18:0 – δ¹³C_C14:0) were determined. Based on the sum of these differential values, criteria were established to detect the presence of beef fat in butter samples: less that –8‰ — natural butter; from –8 to –2‰ — butter with addition of more than 15% of beef fat; over –2‰ — beef fat. If the beef fat content is less than 15%, the samples cannot be distinguished from natural butter by this method. The proposed approach for determining the authenticity of milk fat is less work-consuming and more rapid than the traditional one.

Alumina ceramic specimens with a submicron equiaxed grain microstructure exhibit the highest mechanical performance. However, for certain ratios of fine and coarse grains, the presence of abnormally grown grains may be regarded not as a defect but as a strengthening phase, enabling improved properties, in particular high flexural strength. The aim of this work is to investigate the effect of the volume fraction of abnormally large grains on the strength and fracture toughness of alumina-based ceramics. Abnormal grain growth was achieved during pressureless sintering of submicron α-Al₂O₃ powder. It is shown that, under sintering at a constant heating rate up to a relative density of ~97%, the microstructure consists of equiaxed grains (size ~0.7 μm) and abnormally grown grains (5 vol. %, size >10 μm). By varying the sintering parameters, ceramics with different volume fractions of abnormally grown grains were produced. Increasing the fraction of abnormally grown grains from 5 to 15 vol. % increases the strength and fracture toughness by more than 1.5 times. The improved mechanical properties are attributed to deflection of the crack path from a straight trajectory as the crack bypasses abnormally large grains. The results obtained and the proposed approach may be used to optimise pressureless sintering routes for enhancing the mechanical properties of ceramics.

Tungsten carbide-based ceramics and hard alloys are widely used as the base for metal-cutting and metalworking tools. The purpose of the work is a metallographic study of the effect of large graphite particles in the initial powder on the grain structure of tungsten carbide-based ceramics produced by spark plasma sintering. Before sintering the ceramic samples, large graphite particles of 50 – 500 μm in size were introduced into the initial powder. Digital image processing and statistical analysis methods were used in the work. It was found that an area of large grains of ~10 μm in size (with a submicron grain size in the material bulk) is formed around the graphite particles identified in metallographic sections of the samples. Similar effect upon contact between the workpiece and the graphite tooling is a consequence of carbon diffusion in tungsten carbide. The area thickness does not depend (within the error limits) on the graphite particle size and is 44 ± 9 μm. It was shown that the size distribution of coarse-grained areas can be approximated by lognormal and exponentially modified Gaussian distributions (the distribution modes are 47 ± 4 and 53 ± 7 μm, respectively). The results obtained and the proposed approach can be used to improve digital image processing techniques for metallographic analysis of the microstructure of materials.

Solving the problem of operational nondestructive evaluation of cast aluminum matrix composites is of great practical importance for improving their production technology. The purpose of the work is ultrasonic and microscopic studies of a promising aluminum matrix composite obtained by casting with mechanical mixing of reinforcing hollow ceramic microspheres. Optical and scanning electron microscopy, hydrostatic weighing, and ultrasonic echo method were used to study specimens with different volume fractions of pores and reinforcing microspheres. It is shown that saturation of aluminum matrix with reinforcing hollow microspheres consisting mainly of aluminum oxide makes it possible to obtain the composite less dense than the initial alloy. The main characteristic of the composite structure affecting its properties is the total volume fraction of micropores and reinforcing microspheres. It was found that in the studied specimens, the heterogeneity of the distribution and the average size of the pores and reinforcing microspheres do not affect the propagation velocities of ultrasonic waves and elastic properties. The density, ultrasonic wave velocities, Young’s modulus, and Poisson’s ratio decrease monotonously with an increase in the total volume fraction of micropores and hollow microspheres. It is concluded that the Poisson’s ratio can be used as an informative parameter for rapid quality control of the composite. The results obtained can be used to improve the technique of nondestructive quality control of produced aluminum matrix composites reinforced with hollow ceramic microspheres.

Thin carbon foils are widely used in various fields, including charged particle accelerators. The aim of the work is to study the effect of a high-energy electron beam on the surface structure of a carbon film. Influence of this effect on the service life of charged carbon films was analyzed by bombarding a carbon foil with a beam of high-energy particles. Comparative electron microscopic studies and X-ray spectral microanalysis of the elemental composition of a carbon foil sample after exposure to a high-energy electron beam have been performed. It has been found that in the irradiation area, warping and cracking of the film along the periphery are observed, followed by destruction and separation of the irradiation zone from the foil base. The high-energy effect of charged particles on the foil leads to thermal and radiolytic destruction of the material and the adhesive substrate, accompanied by surface chemical processes. The results obtained can be used to improve the technology for producing stripper carbon foils and increase their service life in charged particle accelerators.

This paper presents the Crack Tip Opening Angle (CTOA) as an effective fracture mechanics criterion for preventing risks associated with pipelines transporting hazardous gases such as hydrogen and ammonia. CTOA is used as a global parameter to characterize resistance to ductile crack propagation and to predict crack arrest conditions in pressurized pipelines. Unlike initiation-based fracture parameters, CTOA directly describes steady-state crack growth and is therefore well suited for assessing long-running cracks that may lead to catastrophic failures. The paper reviews the fracture behavior of pipeline steels, distinguishing between crack initiation and propagation, and highlights the advantages and limitations of the CTOA approach. Several CTOA measurement techniques are discussed, including direct optical methods, indirect load — displacement curve analysis, and fracture surface microtopography. The influence of material properties, specimen geometry, thickness, loading mode, and plastic constraint on CTOA values is examined, with particular emphasis on the significant scatter observed in experimental data. CTOA is implemented in finite element simulations using a node-release technique to model ductile crack propagation and arrest under internal pressure. The predicted arrest pressure and crack length are compared with established approaches such as the Battelle Two-Curves Method, showing good agreement. Once crack arrest is determined, the resulting breach size is used to calculate gas outflow rates. Finally, gas dispersion modeling, combined with CTOA-based fracture analysis, enables the determination of safety distances for toxic or explosive gas releases. A case study using ammonia and the ALOHA dispersion software demonstrates how CTOA can be integrated into a risk-based framework to ensure that lethal risk remains below regulatory thresholds over the pipeline’s service life.

The aim of this study is to investigate the physical and mechanical properties of polymethyl methacrylate (PMMA) brand Plexiglas GS 0Z00 due to the absence of stress-strain curves in open databases, such as CAMPUS or MATDAT. In addition, the mantioned databases contain curves only for tension. Stress-strain curves are necessary for more accurate calculation of the stress-strain state of the body. To determine the performance characteristics of the material, the samples were exposed to climatic action. The results of the experimental study of the physical and mechanical properties of the material before/ after climatic action are presented. Various models that determine the relationship between stresses and strains (the Menges model, the model based on the logistic function) at temperatures below the glass transition temperature are considered. Numerical values of the model parameters are obtained in accordance with the experimental data. The results of tensile-compressive tests at a constant strain rate from 1 to 10 mm/min (from = 3.3 %/min to 33.33 %/min) are compared with the results of tensile-compressive tests of the material at the same rates and room temperature, but after exposing the samples to open air for six months. In addition, the physical and mechanical properties of the material for different ambient temperatures are determined. Stress-strain curves of the material at room temperature are constructed for further use in modeling the stress-strain state of bodies. It is noted that at a deformation of no more than 4%, the Menges model and the model based on the logistic function have proven themselves well. The parameters of both functions for the selected material are presented in the paper. The material has a tendency to embrittlement after climatic aging. The physical and mechanical properties of the material depend on the ambient temperature and the rate of the applied load.

Nonparametric methods of estimation in stochastic systems are certainly more general than parametric estimation methods. The latter assume the presence of a priori information, which ultimately assumes the knowledge of the number of estimated parameters and the structure of the system itself. In nonparametric methods, such information is not required. The paper objective: to develop methods for nonparametric estimation of dependence measures for complexly organized random processes. The article introduces a measure of dependence that links k pairs of random processes. Such a measure, based on the use of conditional mathematical expectations of processes, can be considered as a further generalization of dispersion functions. Convergence with probability 1 of nonparametric estimates of such a measure is derived using sample data. These estimates are used to construct sample analogues of some nonlinear measures of stochastic dependence of random processes, in particular, to obtain a consistent measure of dependence in the sense of Kolmogorov, i.e., a measure that vanishes if and only if the given random processes are stochastically independent. As a direct consequence, the consistency of the measure of dependence in the sense of Rényi, i.e., a measure that satisfies the corresponding Rényi axioms, will immediately follow from the obtained results. The developed estimation algorithms converging with probability 1 do not require any a priori information about the system and can be used to construct input-output mappings of nonlinear systems without any special requirements for the system.