Nowadays, widespread application of engineered nanoparticles (ENPs) inevitably leads to their release into the environment. Soils are regarded as the ultimate sink for ENPs. The study on the mobility of ENPs in soils is important in the assessment of potential risks related to their toxicity. The behavior of ENPs depends not only on the parameters of soil, but also on the exposure scenarios, namely, the amount of ENPs trapped in soil. We studied the mobility of cerium dioxide nanoparticles (nCeO₂) in soils at different exposure scenarios. The relationship between the mobility of nCeO₂ and their concentration in the soil within the range 1 – 1000 ìg/g is evaluated. It is shown that the mobility of nCeO₂ decreases with a decrease in their concentration in the soil and attains the minimum value when the concentration of nCeO₂ goes below 10 ìg/g. In relative units, only about 0.1 – 0.2% of nCeO₂ (in aforementioned concentration range) exhibit mobility and can migrate in the soil profile under saturated conditions. The lion’s share of nCeO₂ (about 99.8%) remains immobile in the soil. Evidently, the vertical transport of nCeO₂ in soil profile should depend on the volume of released suspensions. In the case of small or moderate wet deposition, nanoparticles will accumulate in upper soil horizons characterized with the highest biological activity and thus can affect the soil inhabitants (plant roots, earthworms, insects, microorganisms, etc.).

A set of ICP-AES techniques has been developed for determination of rated elements: Ti, Si, R Al, Cu, Mo, V, Sn, and Zr in ferrotitanium; Ni, Fe, Cu, Co, and As in ferronickel; Si, Cr, and P in ferrochrome silicon; Zr, Si, Al, R and Cu in zirconium ferrosilicon; Mn, Si, and P in manganese ferrosilicon. Combination of the multi-element ICP-AES method which allows precise determination of the elements in ferroalloys in a wide range of concentrations and microwave sample preparation in closed autoclaves which excludes the loss of the components to be determined provides the rapidity of the analysis procedure. The composition of solutions for opening samples of ferroalloys and temperature-time modes of microwave sample preparation in an autoclave are substantiated. Conditions for ICP-AES determination of the rated elements in ferroalloys are studied. Analytical lines of the elements to be determined free from significant spectral overlaps are chosen. The dilution rates of the solutions are determined. The method of internal standard was used to improve the reproducibility of the analytical signal for Ti determination in ferrotitanium, Si and Cr in ferrochrome silicon, as well as all rated elements in manganese ferrosilicon and ferronickel. The spectrometer was calibrated using model solutions and solutions of standard samples added with the certified solutions of the elements to be determined. To determine Ti, Si, FJ Al, Cu, У and Zr in ferrotitanium; Ni, Fe, Cu, and Co in ferronickel; Si, Cr, and P in ferrochrome silicon; Zr, Si, Al, P, and Cu in zirconium ferrosilicon; Si and P in manganese ferrosilicon a multidimensional graduation by two analytical lines was used. The correctness of the determination was evaluated in analysis of standard samples of ferroalloys and comparative analysis of the obtained results with the data of standard methods: comparison of the variances according to the Fisher criterion did not reveal any significant difference between them, whereas the use of the modified Student test showed the absence of the systematic error.

Simple, selective and highly sensitive extraction-photometric methods for determination of Cu, Hg, У Mn, Fe, Co, and Ni are developed using dimercaptophenols (DF) and hydrophobic amines (Am) (2,6-dimercaptophenol(DMP), 2,6-dimercapto-4-methylphenol(DMMP), 2,6-dimercapto-4-ethylphenol(DMEP), 2,6-dimercapto-4-propylphenol(DMPP), and 2,6-dimercapto-4-tertbutylphenol(DMBP)) as complexing reagents. Optimal conditions for formation and extraction of heteroligand compounds (HLC) are specified and the ratios of the components in the complexes are determined. The optimum pH value providing maximum and constant optical density ranges within 3.0-8.1, chloroform (extraction ratio: 98.4-99.6%) being used as an extractant. Optimal concentrations of DP and Am are (0.6 - 0.8) x 10^-3 and (0.8 - 1.2) x 10^-3 mol/liter, respectively. HLC are stable and do not decompose for three days in aqueous and organic solvents, and after extraction for more than a month. The maximum analytical signal for M(II) complexing with DP and Am is observed at 464 - 630 nm (ε_k = 1.82 - 4.40 x 10⁴ ). The structure of the HLC was studied using thermogravimetry and IR-spectroscopy Comparison of the analytical capabilities of the studied reagents showed that the contrast and sensitivity of the reaction decreases in the series DMBP — DMPP — DMEP — DMMP — DME The interfering impact of ions can be eliminated through changing pH of the medium, masking substances and extraction. The limits of photometric detection and quantitative determination of M (II) in the form of HLC were calculated using calibration graphs. The developed procedures have been successfully used in determination of the trace amounts of Cu, Hg, У Mn, Fe, Co, Ni in different soils: sod-podzolic sandy and sandy-loamy sod-podzolic loamy and clayey, gray forest, black soils, chestnut and river (soil of river floodplains) soils. The determination limits range within 27 - 43 ng/cm³ .

The antifriction composite materials (CM) based on a B83 babbit alloy containing silicon carbide (SiC) and modifided shungite (MS) particles have been fabricated by hot pressing. The matrix powder was prepared using a planetary ball mill for processing chips obtained by machining of cast aabbitt. The resulting powder was sieved on a sieve analyzer. Powder mixtures for pressing were prepared by mechanical alloying in a planetary mill for 2 h at a stirring speed of 300 rpm. Composite semi-product was obtained by pressing the obtained powder mixtures on an ОМА mechanical press (P_max = 150 kN) at pressure of 320 ± 5 MPa. Semi-products were heated in a muffle furnace in a mold at a temperature up to 300°C, kept at this temperature for 30 min and then pressed. We have shown that CM obtained using methods of powder metallurgy exhibit increased wear resistance at comparable values of the friction coefficient compared to the same properties of a cast alloy. Local elastic moduli of the obtained samples have been determined using the laser optoacoustic method based on the measurements of the phase velocities of thermo-optically excited longitudinal and shear ultrasonic waves. We have shown that B83-based CM containing MS (0.5 wt.%) and SiC (3 wt.%) can be recommended as an alternative to a B83 cast alloy due to the higher wear resistance compared to cast babbit. The friction surface of this composite material reveals the sliding areas and friction relief less distinct compared to the cast alloy.

A significant part of the elements of machines and structures along with stationary fatigue is subjected to combined impacts of low-cycle and multi-cycle fatigue loading in operation. The physical nature of their fracture in these conditions depends on the ratio of the mode parameters and entails the necessity of advanced research. The predominance of this or that process determines the nature of the damage accumulation which leads to the destruction. Under such conditions, i.e., preliminary cyclic elastoplastic deformation followed by subsequent fatigue loading, the material subjected to preliminary loading at the first stage can be considered the "new material" with the new properties acquired upon cyclic elastoplastic loading which then undergoes further fatigue loading at the second stage. Hence, at the second stage, the new properties of the material are determined by the level of structural changes and damages earlier accumulated in the material. In this case, the damage to the material is considered on the basis of the well-known statement about the staging character of plastic flow, two main processes, i.e., shear, caused by the interaction of dislocations, and destructuring, attributed to violation of the continuity or integrity of the metal. Experimental studies of changes in the durability of cyclically hardened and cyclically softened steel specimens at different levels of preliminary elastoplastic deformation with varying number of cycles and amplitudes of preliminary elastoplastic strain showed the occurrence of an additional damage to the material when combination of loading modes leads to change in the fatigue durability at the subsequent stage of the basic multi-cycle loading. It is shown that correlation between changes in the fatigue durability and structural state of the material, caused by accumulated damage upon preliminary overloads, and, moreover, those changes can be characterized by the ratio of plastic and destructive strains as a Q-factor of the material.

Assessing of the quality parameters of the blade manufacture, which can affect their operational performance, is an important step in determining the causes of turbine blade destruction. Manufacturing defects, despite their great diversity, tend to be stress concentrators. Apart from the defects listed in the specifications to be avoided upon blade manufacturing, we mean also various kinds of defects identified as concentrators that contribute to the destruction of the blades in operation. Assessment of the blade quality suggests identification and analysis of the defects, as well as determination of the technological stage at which they have been formed. For cooled turbine blades this is the foundry stage of their manufacture. Studies of the blades damaged in operation, revealed that despite the control and rejection of blades in the manufacture, the materials of the turbine blades installed on aircraft engines, contain casting defects. The revealed casting defects are shown to affect the strength characteristics and durability of turbine blades and contribute to their destruction through fatigue fracture in operation. The special features of the quality characteristics of the single-crystal turbine blades, affecting their performance, and defects that contribute to their destruction in operation are highlighted. The necessity of improving the valuation, standardization and quality control both at the stages of design and manufacture of blades is shown.

A calculation method for obtaining the misorientation distribution function (MDF) for cubic crystals which can be used to estimate the presence or absence of special boundaries in the materials is presented. The calculation was carried out for two samples of Al-Mg-Si alloy subjected to various mechanical and thermal treatments: the first sample is subjected to rolling; the second sample is subjected to recrystallization annealing. MDF is calculated for each sample; the results are presented in the Euler space and in the angle-axis space. The novelty of the method consists in the possibility of gaining data on the grain boundaries from X-ray texture analysis without using electron microscopy. A calculation involving only mathematical operations on matrices was performed on the basis of the orientation distribution function restored from incomplete pole figures. It is shown that no special boundaries are observed in the deformed sample, whereas in the recrystallized alloy, special boundaries are detected at Ʃ = 23, 13, and 17. The shortcoming of the proposed method can be attributed to the lack of accurate data on grain boundaries, since all possible orientation in the polycrystal should be taken into account in MDF calculation.

The drawing of pipes exposed to ultrasonic vibrations of radial type and their effect on the physical and mechanical properties of the pipe, as well as on the surface quality is studied. The ultrasonic unit with radial vibrations tested under production conditions is used to study the effect of ultrasound on the residual stresses present after drawing, surface roughness, as well as on the physical and mechanical properties and microdefects of 08Kh18N10T steel pipes. Defects and residual stresses before and after drawing under the effect of ultrasound were analyzed by the method of magnetic memory, using the stress concentration meter TSC-4M-16 with an eight-channel scanning device with four two-component sensors (Type 15). It is shown that the residual stresses decreased by more than two times under the effect of ultrasound. The surface roughness after drawing with ultrasound ranged within R_a = 0.087 - 0.092 µm. The physicomechanical properties were studied in tensile tests on an Instron tensile testing machine (SATEC Series). The yield stress q_t was 551, the tensile strength q_in — 672 MPa. It is shown that the effect of ultra-sound upon drawing pipes made of 08X18H10T stainless steel enhance their quality through reduction of the surface roughness and improved physicomechanical properties.

The new paradigm of mathematical research methods is based on the effective application of information and communication technologies both in calculating the characteristics of the methods of data analysis and in simulation modeling. Pseudo-random number generators underlie many modern data analysis technologies. To solve specific applied problems, researchers permanently develop the new methods for processing statistical data, i.e., measurement results (observations, tests, analyzes, experiments) and expert estimations. The properties of each newly proposed method must be studied. The intellectual tools are limit theorems and method of statistical simulations (Monte-Carlo method). In 2016, our journal opened a discussion on the current state and prospects for the development of statistical modeling, i.e., the theory and practice of applicating the method of the statistical simulations (Monte-Carlo method), and various variants of the simulation. The previous discussion about the properties of such generators was conducted in our journal in 1985 - 1993. This article is devoted to application of the statistical simulations method to the study of the properties of statistical criteria for testing the homogeneity of two independent samples. We consider: the Kramer - Welch criterion, which coincides with Student's criterion when sample sizes are equal; the criteria of Lord, Wilcoxon (Mann - Whitney), Wolfowitz, Van der Waerden, Smirnov, со 2 (Lehmann - Rosenblatt). It is necessary to set the distribution functions of the elements of two samples. We use the normal and Weibull - Gnedenko distributions. It is shown advisable to use the Lehmann - Rosenblatt со 2 test when testing the hypothesis of coincidence of the distribution functions of two samples. If there is a reason to assume that the distributions differ mainly in the shift, then the Wilcoxon and Van der Waerden criteria can be used. However, even in this case, the со 2 test may be more powerful. In the general case, apart from the Lehmann - Rosenblatt criterion, the use of the Smirnov criterion is permissible, taking into account the difference between the real level of significance and the nominal one. The frequency of the discrepancies of statistical findings based on different criteria is studied.

Original approaches to enhancing the efficiency of production meetings are developed. Basic hypothesis and promising lines of research that can promote the efficiency of production meetings are reviewed. A number of Russian and foreign scientific journals mistakenly treat some types of operational meetings as brainstorming although some of the procedures contain no mechanisms inherent in brainstorming, which can thus lead to a confusion with their use. We propose to: 1) take into account the difficulties in identify ing the type of meeting procedure; 2) consider and use the existing procedures, techniques and methods for setting goals by the supervisor and their subsequent adjustment; 3) use the basic decision-making models for enterprises and organizations, i.e., select the most appropriate types of meetings proceeding from their advantages and shortcomings; 4) use the psychology of small groups and methods for stimulating small groups and teams. Avoid spontaneous selection of meeting and choose the best category of meeting proceeding from the advantages and disadvantages of this category of meeting among others. It is recommended to use three kinds of selection tasks in the context of group selection theory (selecting of the best or appropriate single object from the given set): selection of subsets in which all L selected best objects are supposed to be used without dropping out any of them, where L > 1; simultaneous selection of the subsets consisting of a different number of elementary alternatives in which it is supposed to use all the selected best objects without dropping out any of them, including the case when one object is selected and compared (elementary motion); application of the results of interrogative logic. It is necessary to objectify the process of searching for compromises (agreement of opinions) of the participants of the meeting, expressed in various non-verbal types of assessments, i.e., to use a discrete or statistical approach to aligning expert rankings of the participants of the meeting. The novelty of the work is expressed by the fact that for the first time an emphasis has been placed on those areas that are usually not associated with an increase in the efficiency of production meetings. Moreover, the scope of the concept of "meeting" has been narrowed, and a special class of production meetings has been identified and described.