The review is devoted to the analysis of literature data on the development of modern electrochemical sensors for the determination of carbofuran in natural objects (water, soil, food). Sensors for the determination of carbofuran can be conditionally divided into two groups according to the type of electrode materials used: carbon-containing and biosensors. Carbon-containing sensors manufactured using nanotechnologies based on 0D – 3D allotropic modifications of carbon (carbon black, graphene, carbon nanotubes, fullerene) exhibit unique properties such as structural polymorphism, high surface area, thermal and chemical stability, biocompatibility, and original catalytic properties. At the same time, biosensors are considered promising analytical systems that complement traditional analytical methods due to the possibility of rapid on-site monitoring and miniaturization. Currently, biosensors used for the determination of carbofuran are mainly divided (proceeding from the type of bio-recognition elements) into enzyme biosensors (acetylcholinesterase and other enzymes) and immunosensors (antibodies and aptamers). Two detailed tables present data on electrochemical sensors developed for the determination of carbofuran in natural objects, including their advantages and shortcomings. All the developed sensors for the determination of carbofuran are characterized by high sensitivity, selectivity, rapidity, and low manufacturing cost, which makes electroanalytical methods a worthy alternative to the methods of analysis traditionally used for the determination of pesticides (liquid and gas chromatography, spectrophotometry, capillary electrophoresis, etc.). Preparation of vegetable and fruit samples for analysis using sensors of various types is described: the main stage of sample preparation is the alkaline hydrolysis of carbofuran, which is electrochemically inactive, to carbofuran-phenol. This review may be of interest to laboratories for the quality control of agricultural products and foodstuffs.

A distinctive feature of modern drugs is a complex multicomponent composition, including both medicinal and auxiliary substances. The synthetic food dye Quinoline yellow (QY) is widely used for color correction, however, the determination of QY by the spectrophotometric method is impossible without separating the preparation from the matrix. Micellar extraction with polyoxyethylated alkylphenols Triton X-100 and OP-10 is proposed as an alternative to solid-phase extraction and traditional extraction with organic solvents. The phase separation of aqueous and aqueous-salt solutions of Triton X-100 and OP-10 with a con-

centration of 1 to 10% is studied in various modes: polythermal (when heated to cloud point) and isothermal (salting out at 25°C). Sodium and ammonium sulfates and sodium carbonate are used as salting-out agents. Their salting-out ability decreases in the series Na₂CO₃ > Na₂SO₄ > (NH₄)₂SO_4. The effect of the acidity of the medium and the nature of the electrolyte on the state of the QY in aqueous and aqueous micellar solutions is also studied. The form of the dye does not change within the pH range 1 – 8 and with the addition of Na₂SO₄, (NH₄)₂SO_4. At higher pH values and in the presence of Na₂CO₃, structural changes occur in the molecule. The intensity and position of the maximum in the absorption spectrum change in the presence of surfactant micelles (bathochromic shift, Δλ = 8 nm). The dye distribution between the aqueous and micellar phases is studied in different modes of phase separation. It is shown that the systems with the addition of sodium and ammonium sulfates in the salting-out mode (R > 97%) have the best extraction characteristics. Optimal conditions for the maximum single extraction of the dye in the concentration range of 1 – 10 mg/liter in the aqueous solution C(surfactant) — 10%, solution volume — 10 ml, Na₂SO₄ — 0.84 g, temperature — 25°C, time — 30 min. A rapid and easy to use method of QY extraction concentration from orodispersible tablets (lozenges) is developed. The error of the method does not exceed 5%. The verification of the correctness of the method, carried out by HPLC, proved the absence of a systematic error.

The internal state of the material formed as a result of technological processing, indirectly affects the state of the material surface. A non-contact method of non-destructive control of the state of materials based on a visual analysis of the surface, requires high-quality images which can be obtained either using lens objectives or lenseless technologies. The results of studying image processing obtained by lensless technologies are presented. We used methods for modeling phase masks and image processing based on Gerchberg – Saxton iterative algorithms, adaptive-additive and phase mask rotation based algorithms. Materials such as granite, graphite, sand and carbon steel were analyzed. It is shown that the construction of cameras can provide significant reduction of their dimensions at the same or even improved characteristics. The images obtained using lensless technologies and the proposed methods of image processing also provide a significant increase in the accuracy of visual inspection of materials. The results obtained can be used in refining lensless technologies, improving the quality of images and reducing time of their processing.

The electrical conductivity of powder media depends on the composition, impurities, oxide films, morphology and the nature of the contact surface. We present the results of studying the electrical resistance of powder materials and their compounds under continuous loading by the four-contact method. The electrical resistance is determined using a special experimental cell. Industrial powders Al (ASD-1), Ti (PTK), Hf (GFM-1), soot and their mixtures, as well as TaC and HfC powders obtained by self-propagating high-temperature synthesis were studied. It is shown that an increase in the mechanical pressure up to 80 MPa leads to a decrease in the electrical resistance of the materials under study. The morphology of the particles (spherical or fragmentary shape), their dispersion affects the quality of the contact surface and, accordingly, the magnitude of the electrical resistance. Moreover, the electrical resistance of the material depends on the degree of cleaning of the particle surface from oxide films. The proposed method in combination with other analytical methods used for studying powder media allows us to reveal the regularities of this relationship, characteristic of all morphological features, composition and electrophysical properties of powders of various compositions under loading conditions. The results obtained can be used to select the optimal characteristics of consolidation by electric current depending on the initial pressure, as well as in case of high-voltage electric pulse consolidation of powder materials by spark plasma sintering and electrothermal explosion methods.

The quality of 3D printing depends on the properties of consumables, in particular, on the chemical composition of the powders, the size and shape of their particles. To eliminate printing defects, the working mixture of primary and secondary powders based on polyamide-12 should contain no more than 30% of the secondary powder. We present the results of studying the fractional composition of powders by the methods of statistical analysis. Digital images of polymer samples including morphological parameters of particle images were analyzed. To assess the fractional composition of the particles of primary and secondary powders, a statistical method of dimensional ranking and a differential method for determining the boundaries of fractions were used. It is shown that the particle area is the parameter most sensitive to changes in the structure of powders. The results of statistical ranking of effective particle radii are obtained proceeding from the histograms of the particle area distribution. The boundaries of the conditioned fraction are determined by the magnitude of the effective radii. A comparison of the fractional composition of primary and secondary powders, as well as calculation of the percentage of fine, working and large fractions were carried out taking into account the assessment of the fraction boundaries. It is revealed that the content of fractions of powder particles with conditioned dimensions should be about 64% of the total volume of the powder. Reduction of the amount of primary powder can lead to defects in 3D printing. The results obtained can be used to increase the degree of recovery of polyamide-12 based powders during 3D printing.

The possibility of assessing the safe size of the defects of metal continuity using risk criteria are considered. Such defects occur at all stages of the life cycle of structures. Assessment of their hazard and determination of their allowable size becomes important when the defects can lead to brittle or quasi-brittle fracture. In this case, models of linear and nonlinear fracture mechanics are used. In these models, defects are considered as internal elliptical or surface semi-elliptical cracks. The stochastic variety of shapes, sizes, locations, and orientations of defects has a significant effect on the destruction mechanisms. In this regard, the relevant probabilistic problem of assessing the permissible size of defects according to the criteria of the risk of destruction comes to the fore. We consider a general approach to assessing hazard of defects by risk criteria. Two settings of the probabilistic problem of risk assessment based on of one- and two-parameter fracture criteria are presented. The risk function in the form of the probability of fracture according to a given criterion is used as the main calculated characteristic. The expression of the risk function based on one-parameter criteria of fracture mechanics is presented. The main attention is paid to the probabilistic model based on the two-parameter fracture criterion by E. M. Morozov. This criterion provides ample opportunities for analyzing fracture mechanisms with a change in the size of defects. An expression for the risk function based on the family of two-dimensional probability distributions of Lu – Bhattacharya of the Weibull type is obtained. It is shown that the correlations of the fracture mechanisms can significantly affect the values of the fracture probabilities, and, consequently, the allowable size of defects.

The mechanical properties of square section (up to 350 mm) forgings made of domestic steel VKS-9M (obtained by the duplex process of vacuum induction melting plus vacuum arc remelting) are studied. The mechanical properties of steel VKS-9M and American high-strength structural steel 300M are compared in terms of the calculated characteristics of materials. We extend the concept of «design characteristics of materials» to all the mechanical properties of materials used in determination of the strength and durability of structures. The design characteristics of materials include the strength characteristics under quasi-static tension, compression, crushing and shearing, as well as the strength under variable loads and the crack resistance of the material. The correctness of comparing the calculated values of the static strength of steels VKS-9M and 300M is based on the identity of test methods and the equivalence of processing and presentation of test results. The determination of the strength characteristics was carried out according to domestic standards, which are basically harmonized with the American standards. A difficult situation arises when determining the strength indicators of a newly developed material. Nowel material, as a rule, is developed in laboratory conditions, produced on experimental equipment in small volumes, and, therefore, the statistical assessment of the general population at the development stage is unreliable. In conditions of the full-scale manufacture of industrial semi-finished products, a statistical assessment of their strength characteristics becomes necessary. In the aviation industry, a statistical assessment of the calculated values of the strength characteristics of the material is prescribed by the law. The airworthiness standards set the levels of the calculated values of strength characteristics with a certain probability of non-destruction. For parts, the destruction of which can lead to an accident, the calculated values of the strength characteristics of materials should be selected in such a way that the strength of the material is to be ensured with a probability of 99% — with a 95% confidence interval (basis «A»). Statistical evaluation of the static strength characteristics of two heats of VKS-9M steel on the basis of «A» revealed their insignificant excess in comparison with steel 300M. The data obtained allow us to believe that the calculated values of the static strength characteristics of VKS-9M steel will not be lower than the calculated values for 300M steel. Large-scale fatigue tests of VKS-9M steel were carried out, which proved that the fatigue characteristics of VKS-9M and 300M steels practically coincide, as well as the arrays of their determinations. The equivalence of the strength characteristics of the VKS-9M and 300M steels allows replacement of the American 300M steel by the domestic VKS-9M steel.

Decision theory is an important component of the methods of mathematical research. We consider some aspects of the application of decision theory to the development of complex technical systems. The main attention is paid to the methods of forming the estimated indicators and then the estimates of the quality

and technical level of complex technical systems on their base. The use of decision theory in the development of an automated system for predicting and preventing aviation accidents is discussed. An approach to choosing the priority of R&D in the rocket and space industry is presented as an example. To implement the project management toolkit, five criteria are proposed for choosing the priority of projects taking into account the peculiarities of space activities in Russia. After forming a list of possible projects, it is necessary to set priorities, i.e. to arrange them in order of preference for implementation. To set priorities, we propose to use methods of expert assessments. The priorities are determined by a commission of experts appointed by the order of the head of the enterprise. In decision theory, two approaches have been developed to set priorities based on expert assessments — using direct comparison of the objects of the expertise and using expert assessments of the objects of the expertise by a set of factors. The first approach is implemented by comparing the ranks by the arithmetic mean, and then the medians of the ranks thus obtaining two auxiliary clustered rankings with subsequent construction of the matching ranking. Another way to find a consensus of the expert commission is based on the calculation of the Kemeny median of expert orderings. In the second approach, objects of the expertise are ordered not directly, but using the values of a certain set of factors. For each object of the expertise, the values of factors included in this list are determined (usually with the help of experts). The values of the factors are combined in an integral indicator of the priority of projects. To calculate the integral indicator, weighted Kolmogorov averages and weighted medians can be used.

The problem of estimating the closeness of co-relation (interdependence) between several random vectors of arbitrary dimension is considered. These random vectors can have arbitrary multidimensional continuous distribution laws. Earlier, within the framework of the entropy approach, indicators were obtained for estimating the closeness of the correlation relationship between the components of one random vector and between two random vectors. The goal of the study is to generalize the previously obtained results to the case of several random vectors. The analytical expression for the coefficient of the closeness of co-relation between several random vectors is obtained. This coefficient is expressed through the indices of determination of conditional regressions between the components of random vectors. For the introduced scalar measure of the relationship, a number of particular results were obtained, which turned out to be known correlation coefficients. A rather simple formula expressed through the determinants of each random vector and the determinant of their combination is derived for the case of Gaussian random vectors. The proposed coefficient can be used to study the network structures consisting of many subsystems. In particular, the interpretation of the correlation coefficient between the elements of the network structure and the other elements can be introduced as the correlation coefficient of the system at the vertex. The introduced measure is quite simply interpretable and allows an unambiguous assessing of the closeness of co-relation between several random vectors of arbitrary dimensions and can be used on real data samples. An example of calculating the closeness of the co-relation between three Gaussian random vectors is presented.