The goal of this study is development of the method for studying the chemical composition of natural and synthetic nitrogen-containing compounds using electron probe microanalysis (EPMA) and the use of EPMA for identification of the form of occurrence of light elements (C, N, O) in complex anions and cations. The analysis was performed using Kα lines attributed to electronic transitions from valence 2p states to internal 1s states. The characteristic features of the Kα spectra of C, N, O, which affect the correctness of the EPMA results were revealed to introduce the corrections that take into account the integrated line intensity, the effect of self-absorption of the nitrogen line and absorption of the background by nitrogen.

The method is intended for studying different nitrogen-contained samples including diamonds obtained by detonation synthesis. The surface of these samples is usually covered with a layer oxygen- and nitrogen-containing functional groups. The main problem associated with the experiment is determination of optimal conditions for excitation and registration of Kα lines. The accelerating voltage used is 10 kV, the beam current is 50 – 120 nA. In the analysis in the differential mode of recording the signal amplitude we use the same (for all samples) empirical formula to describe the shape of the background intensity curve in the vicinity of the nitrogen line. The resistance of the samples to the impact of the electron beam is increased when using a raster mode with a linear size of 20 – 40 μm and sample movement within the area ~100 × 100 μm² (if possible with allowance for the sample size). The concentrations of the determined elements were calculated using the PAP program with B. L. Henke absorption coefficients. The detection limits of carbon, oxygen and nitrogen at a current of 80 nA were 0.33, 0.46 and 0.86 wt.%, respectively.

The phase separation in Na₂O-CaO-SiO₂ system containing four different microcomponents (Fe₂O₃, P₂O₅, Ag, Au) is studied. Two glass samples of close composition have been synthesized with the same set of the microcomponents and different content of gold and silver. Both glass samples have been melted in an open platinum crucible in an electric furnace at 1400°C for three hours and then poured and quenched on a cast iron plate and annealed at 520°C for one hour. Formation of the nanoparticles occurred upon secondary heat treatment at 550 – 600°C. The phase separation in the glass sample with a composition corresponding to the immiscibility limit in the NCS system occurs through formation of the core – shell type gold-silver nanoparticles, which serve as nucleation centers for the droplets of the second glass phase enriched in silica. Eventually, quartz crystallizes inside the droplets. The impact of these processes on the optical properties of the material including dichroism is discussed. The phase separation and quartz formation are confirmed by SEM and X-ray analysis data, respectively. The size of the nanoparticles was calculated from electron spectra using computer simulation. Iron in the glass samples thus obtained is in oxidation states +2 and +3, which determines the color of the glass before and after the secondary heat treatment in reflected light. The glass color in the transmitted light after the secondary heat treatment is attributed to the light absorption by nanoparticles. The dependence of the nanoparticle shape on the gold-silver ratio in glass is presented. The shape of nanoparticle is close to oblong or oblate ellipsoid within the range of the gold – silver ratios considered in the study.

A technique for analysis of fluorine-containing gas mixtures for excimer lasers, which provides fluorine determination in the range of 0.1 – 5 % mol. with a relative error of less than 6 % is presented along with an installation intended for the composition control of the aforementioned mixtures. Known industrial processes of removing fluorine from gaseous wastes suggest using of active alumina. We measured the adsorption capacity of alumina with respect to elemental fluorine, however, the measured value turned out to be two orders of magnitude less than the theoretical value calculated under the assumption of monomolecular adsorption (0.255 g F/1 g of adsorbent) which can be attributed to a low adsorption activity of the alumina surface. To activate the adsorbent surface, halogen-containing activators — potassium bromide and potassium iodide — were tested, which interact with fluorine, turning it into non-volatile potassium fluoride and free bromine or iodine. These components are well adsorbed on alumina, giving it a yellow or brown color. Activation of the adsorbent surface is proved experimentally, since the capacity of the activated sorbent is fifteen times as much the amount of fluorine bound by a chemical reaction, and the total adsorption capacity of aluminum oxide increases by a factor of 80 compared with an inactive adsorbent.

New possibilities for diagnosing the structure of carbon materials by X-ray diffraction analysis are described. The studies were performed on an X-ray diffractometer D8 ADVANCE (filtered CuKα radiation) using carbon fibers (CF) differed in the mode of heat treatment (~2300 to ~3000°C). It is shown that when studying the structure of fibrous carbon materials characterized by a large depth of X-rays penetration, it is necessary to limit the thickness of the object under study to ~0.1 mm to provide the self-focusing condition for the entire sample volume engaged in formation of the diffracted beam. The material of high modulus carbon fibers can be heterogeneous and contain coherent scattering regions wherein the crystal structure parameters are somewhat different and experimentally observed diffraction peaks 002, 004, and 006 become asymmetric and are not described by the Gauss, Lorentz, or Voigt functions. Thus, the standard method used for determination of the average value of the interplanar spacing and the size of coherent scattering regions does provide reliable information on the real structure of the material. The profile of the asymmetric diffraction peak 002 was analyzed using the Origin program thus providing information about fine (heterogeneous) structure of the carbon fiber material which largely determines the physicomechanical properties. The data on 002 diffraction peak profiles of carbon fibers before and after removal of the CuKα₂ component are presented. The data on decomposition of the experimentally observed asymmetric 002 diffraction peaks into symmetric peaks described by the Gaussian, Lorentz, and Voigt functions are compared. The most preferable is the decomposition into the components described by the Gaussian or Voigt functions.

Creation of the new technologies includes the development of the materials, among which composite amorphous-nanocrystalline materials, characterized by a unique combination of the magnetic and mechanical properties (high strength, hardness, wear resistance, etc.) hold a specific position. However, their potential application is limited due to the loss of plasticity (embrittlement) which occurs relatively soon even at room temperature and cannot be restored by heat treatment of the amorphous phase. The plasticity can be restored when thermocycling is carried out in a temperature range between the temperature of liquid nitrogen (77 K) and room (295 K) temperature. This process dubbed «rejuvenation» turned out to be acceptable only for bulk samples obtained in the form of rods etc. and appeared to be entirely unsuited for ribbon samples with a thickness of 20 – 50 μm (i.e., the thickness of the absolute majority of amorphous alloys currently obtained). We present a modernized method for processing thin samples of amorphous and partially crystalline alloys using cryogenic thermocycling, which provides restoration of the amorphous structure and ductility of the samples. X-ray diffraction patterns of tape samples of Al₈₇Ni₈Gd₅ alloy annealed at 170°C with a fraction of the nanocrystalline phase not exceeding 10% before and after several successive cooling-heating cycles show that with an increase in the number of cycles up to two hundred the amorphous structure of the initial sample can be completely restored.

Mileage is one of the main criteria for replacing engine oil during car operation. At the same time, the problem of timely monitoring the state of working oil due to the lack of control at enterprises and service stations remains an urgent challenge. The results of studying Ravenol 5W-40 SN/CF and Mobil 1 New Life 0W-40 SN/SM/SL/SJ synthetic motor oils using a photometric device which allows direct photometric measurements of samples are presented. A method intended for control of the intensity of aging processes is proposed, including determination of the increment in the rate of change in the absorption coefficient of the light flux as a function of the vehicle mileage. Aging of the oil is shown to be an unstable process which is attributed to the formation of aging products of different optical density and energy intensity. It is also shown that the intensity of aging depends on conditions and operating modes of the engine, technical condition and performance of the cleaning system. The proposed method for monitoring the condition of motor oils during engine operation is proved to be effective. The individual character of aging processes is proved, the intensity of aging can be estimated by the incrementing rate of change of the light flux absorption coefficient depending on the vehicle mileage.

The kinetics of fracture of structural bonds in a unidirectional laminate package under the effect of tensile load is studied using acoustic emission (AE) combined with video recording. A correspondence between the fractures occurred at micro-, meso-, and macroscale levels of the laminate package and the location pulses thus recorded, their energy parameters, shape and spectrum is determined. Data on testing of the new criterion parameters used in acoustic emission monitoring, including the frequency of registration of location pulses in energy clusters and their weight content, as well as the methods providing separation of location pulses into the lusters with similar spectra related to the same or similar types of acoustic emission events are presented. The proposed parameters and structural-phenomenological approach implemented through dividing the entire array of acoustic-emission data into energy clusters make it possible to quantify the degree of destruction of structural bonds of structural material at all scale levels and predict the residual strength of the product. Fusion of the acoustic emission events recorded at different stages of specimen loading and images of video recording of damage accumulation and fracture of the structural bonds in a unidirectional laminate package revealed the a correspondence between the fracture of the composite occurred at micro-, meso- and macro-scale levels, acoustic waves thus generated and location pulses, their energy parameters, shape and spectrum.

Metal stents used to restore the lumen of stenotic blood vessels remain in the human body for life after their implantation. Their high fatigue strength and durability are necessary conditions for the successful use of the implants. Devices intended for testing the fatigue durability of stents are most often based on using a polymer tube of changeable diameter which imitates the blood vessel into which the stent of the corresponding size is placed. The devices are often foreign made and rather expensive. The authors developed a relatively simple and not expensive research facility in which cyclic loading is realized by «rotating bending» scheme. A stent is placed inside the silicone tube having the diameter corresponding to that of the blood vessel in which the stent will be installed. The ends of the tube are fixed on the rotating shafts, which in turn are located in the bearings. Moving one of the bearings changes the bending radius of the tube R and, accordingly, the degree of deformation of the stent elements. The platform with the stent is located in the tank filled with saline solution. A radiator maintains a constant temperature inside the tank. The rotation frequency can be varied up to 60 Hz, five stents can be tested simultaneously. Cyclic loading is realized with a stress ratio equal to 1. We have tested two typical sizes of self-expanding stents made of the alloy based on titanium nickelide: the first being 8 mm in diameter and 60 mm in length, and the second one — 4 mm in diameter and 30 mm in length. The temperature of the saline solution was (37 ± 2)°C, the rotation frequency of the shaft — 50 Hz. The bending radius was R » 250 mm. Tests showed that the developed device can be effectively used for accelerated fatigue tests of stents.

Forty years ago, the statistics of nonnumeric data was singled out into an independent area of mathematical research methods. First the term «statistics of objects of nonnumeric nature» was used. The textbook on nonnumeric statistics is entitled «Nonnumeric Statistics». Statistics of nonnumeric data is one of the four main fields of applied statistics (along with the statistics of numbers, multivariate statistical analysis, statistics of time series and random processes). Statistics of nonnumeric data is divided into statistics in spaces of general nature and sections devoted to specific types of nonnumeric data (statistics of interval data, statistics of fuzzy sets, statistics of binary relations, etc.). Currently, statistics in spaces of general nature is the central part of applied statistics, and the statistics of nonnumeric data that includes it is the main area of applied statistics. This statement is confirmed by analysis of publications in the section «Mathematical Methods of Research» of our journal. This article is devoted to analysis of the main ideas of statistics of nonnumeric data against the background of the development of applied statistics on the basis of the new paradigm of the methods of mathematical research. Different types of nonnumeric data are considered along with the history of development of the statistics of nonnumeric data and statistical science. The basic ideas of statistics in spaces of general nature are analyzed: mean values, laws of large numbers, extreme statistical problems, nonparametric estimators of the probability distribution density, classification methods (diagnostics and cluster analysis), and statistics of the integral type. Some statistical methods for data analysis in specific nonnumeric spaces are briefly discussed: nonparametric statistics (in most cases, real distributions significantly differ from normal), statistics of fuzzy sets, expert estimation theory (Kemeny median as a sample average of expert orderings), etc. Some unsolved problems in statistics on nonnumeric data are also discussed.