Search

Objective: to determine the content of hormones, as well as some macro- and microelements in athletes-wrestlers outside the period of competition and active training.Materials and methods: the study involved 66 athletes-wrestlers and 107 students involved in sports professionally. The level of hormones and vitamin D was determined by the ELISA method. To analyze the content of macro- and microelements, the subjects were cut off a lock of hair from the back of the head in an amount of at least 0.1 g. The studies were carried out on an ICP-MS Agilent 7900 mass spectrometer.Results: levels of cortisol, TSH and T4 are higher, and levels of testosterone, T3 and vitamin D are lower in athletes compared to the control group. An increase in the content of sodium, calcium, potassium, magnesium, cobalt and a decrease in iodine were revealed in fighters from those who were not involved in sports professionally.Conclusion: the data obtained indicate an imbalance in the work of the body’s endocrine systems and impaired adaptation to stress. It is known that the determination of the hormonal status is used to assess the adaptation, the revealed changes in the indicators of vitamin D, macro- and microelements, allow the study of these indicators in order to prevent the syndrome of overtraining of athletes, to maintain and improve sports performance.

The electrophysical characteristics of a multilayer memristive Au/Ta/ZrO2(Y)/TaOx/TiN structure have been studied. Electron and ion electret effects due to charge carrier trapping and ion migration polarization in the dielectric have been discovered. The influence of traps on electroforming processes and resistive switching has been established. The values of activation energy and ion and trap concentrations have been determined. The effect of resistive switching stabilization has been found, which is associated with the specific bilayer structure of TaOx and self-forming tantalum nanoclusters. The nanoclusters serve as electric field concentrators in the course of electroforming and subsequent resistive switching.

The article rises the current question about the need to develop a fire safety system of explosive objects (buildings, structures, buildings, industrial communications), as well as organizing assistance to local self-government bodies in the implementation of primary fire safety measures. The emphasis is placed on a fire prevention system, which includes a lightning protection system designed to protect the countryside and other objects of protection against atmospheric electricity discharges. Therefore, for proper design, control and maintenance of health, it is proposed to apply the original computer program. Which allows an express analysis of lightning protection parameters and make appropriate conclusions.

We have studied the resistive switching in memristive structures based on 40-nm-thick yttria-stabilized zirconia (YSZ) films exposed to 6-keV Si+ ion irradiation to a total dose of 5.4 × 1015 cm–2. It is established that the ion irradiation leads to increased stability of the parameters of resistive switching in YSZ based memristive structures. This effect is related to the fact that the diameter of conducting filaments in irradiated structures is limited by lateral dimensions of the region of atomic displacement cascades (i.e., the region occupied by point defects produced by bombarding ions). The oxidation of ion-modified filaments during resistive switching proceeds more effectively and leads to increasing resistance in the high-resistance state of memristive structures.

To improve the accuracy of the obtained values when predicting the fire hazardous properties of organic substances, it was decided to modify the existing algorithm, supplementing it with deep learning technology. Verification of the data was carried out based on some reference and practical data. It was found that the values obtained in the course of computer simulation provide a satisfactory error, which means that the data obtained can be used in practice.

The stochastic resonance phenomenon has been studied experimentally and theoretically for a state-of-art metal-oxide memristive device based on yttria-stabilized zirconium dioxide and tantalum pentoxide, which exhibits bipolar filamentary resistive switching of anionic type. The effect of white Gaussian noise superimposed on the sub-threshold sinusoidal driving signal is analyzed through the time series statistics of the resistive switching parameters, the spectral response to a periodic perturbation and the signal-to-noise ratio at the output of the nonlinear system. The stabilized resistive switching and the increased memristance response are revealed in the observed regularities at an optimal noise intensity corresponding to the stochastic resonance phenomenon and interpreted using a stochastic memristor model taking into account an external noise source added to the control voltage. The obtained results clearly show that noise and fluctuations can play a constructive role in nonlinear memristive systems far from equilibrium.

New approaches to increasing the efficiency of dislocation radiation in silicon, which is promising for use in optoelectronics, are considered. The anomalous temperature dependence of the luminescence of dislocation structures in silicon formed by implantation of Si+ ions and modified by ion doping with boron at different doses is discussed.

Resistive switching and adaptive behavior of resistive state in response to electrical stimulation has been studied for the silicon oxide based memristive devices subjected to electroforming in the conditions of current compliance in comparison with the analogous memristive devices after electroforming without any current limitation. The limitation of current and temperature during electroforming affects the parameters of growing conductive filament ensembles and reduction-oxidation reactions resulting in a gradual character and a wide dynamic range of resistance change important for neuromorphic applications.

The effect of boron implantation on the light-emitting properties of dislocation structures formed in silicon by Si+ ion implantation with subsequent annealing is studied. It is shown that the implantation of B+ ions has a significant effect on the dislocation-related luminescence intensity, spectrum and the temperature dependence of the D1-band intensity. It is found that the temperature dependence is nonmonotonous and involves two regions, in which the D1-band intensity increases with increasing temperature and has two well-pronounced maxima at 20 K and 60–70 K. The maximum at 20 K is associated with the morphological features of the dislocation structure under study, whereas the maximum at 60–70 K is associated with the additional implantation of the boron impurity into the dislocation region of the samples. It is established that the intensities of the experimentally observed maxima and the position of the high-temperature maximum depend on the implanted boron concentration.

Gallium oxide nanocrystals encapsulated in Al2O3 film on a Si substrate have been synthesized by using ion implantation followed by thermal annealing at 800 °C or 900 °C. Formation of $\beta $ -Ga2O3 nanocrystals is confirmed by transmission electron microscopy. The photoresponse of a photodetector fabricated on the implanted layer by the deposition of interdigitated electrode pattern is estimated by analyzing the current–voltage characteristics. The ratio of photocurrent at the wavelength of 250 nm and a voltage of 4 V to dark current around ~15 is found for the sample annealed at 900 °C. The spectral dependence of photoresponse for this sample demonstrates excellent solar-blind ultraviolet characteristics in the wavelength range of 250–270 nm with a rejection ratio 42 at the bias of 1 V. At the bias of 4 V, the responsivity of 50 mA/ $\mu \text{W}$ upon illumination at 250 nm and a cutoff at 280 nm are observed for the 900 °C annealing. The sample annealed at 800 °C shows lower ultraviolet responsivity due to the high density of defects. The data are analyzed in relation to the generation of carriers in Ga2O3 nanocrystals and their transport in the damaged Al2O3 matrix. The reported results pave the way toward the fabrication of next generation high sensitive solar-blind photodetectors.

Bipolar resistive switching of the metal-insulator-semiconductor (MIS) capacitor-like structures with the inert Au top electrode and Si3N4 dielectric nanolayer (6 nm thick) has been investigated. The effect of highly doped n+-Si substrate is revealed related to the changes in semiconductor space charge region on the small-signal parameters of parallel and serial equivalent circuit models measured in the high- and low-resistive capacitor states, as well as under laser illumination. The increase in conductivity of semiconductor capacitor plate significantly reduces the charging and discharging times of capacitor-like structures.

Synthesis and modification of gallium oxide as a wide-bandgap semiconductor is a topical task in the fields of power electronics, UV detectors, gas sensors, telecommunication. In the present work, the Ga2O3 films deposited on sapphire substrates by magnetron sputtering have been studied. The influence of deposition parameters and subsequent annealing on the structure and optical properties of the synthesized films is analyzed. Ion doping of magnetron-deposited films with silicon is carried out by the ion implantation method. It is shown by the Raman scattering and optical transmission spectroscopy that ion irradiation leads to the disordering of the crystal structure, but subsequent annealing results in a partial recovery of the structure. Hall-effect measurements for irradiated and then annealed films do not reveal the formation of a conducting layer. Apparently, this is due to the fact that the main contribution to the resistance is made by grain boundaries in the magnetron-deposited films.

A physical model of synaptically coupled neuron-like generators interacting via a memristive device has been presented. The model simulates the synaptic transmission of pulsed signals between brain neurons. The action on the receiving generator has been performed via a memristive device that demonstrates adaptive behavior. It has been established that the proposed coupling channel provides the forced synchronization with the parameters depending on the memristive device sensitivity. Synchronization modes 1: 1 and 2: 1 have been experimentally observed.

Within the framework of the study, the process of evaporation of heated high-temperature oil products was studied, the results were used to determine the calculated values of the mass of vapors formed during the evaporation of spills of liquids heated above the design temperature. The result of the study was the development of a theoretical model based on the Stefan formula describing the rate of evaporation. This made it possible to establish that when heating high-temperature organic compounds form explosive vapor-air mixtures that pose a fire hazard.

To study the mechanism of a 9R-Si hexagonal phase formation upon ion irradiation of the SiO2/Si system, three types of experimental samples have been investigated by photoluminescence (PL) spectroscopy and transmission electron microscopy (TEM): SiO2/Si system irradiated by Kr+, silicon irradiated by Kr+ and silicon irradiated by (Kr+ + O+) ions. All the samples were annealed after irradiation. The first type sample shows the presence of the 9R-Si phase and PL band at ∼ 1240 nm; the third type sample shows the same PL band and twin defects; for the second type sample, the PL at 1240 nm is not detected. Based on the results, the role of mechanical stresses, radiation defects and oxygen in the formation of the hexagonal silicon phase is discussed.

The structure and optical properties of thin films of the chalcogenide semiconductor Ge2Sb2Te5, deposited by magnetron sputtering, was studied. A significant change in the topology and optical properties of the films is demonstrated with varying deposition conditions. It is shown that an increase in the deposition time leads to an increase in the surface roughness. Doping with nitrogen during deposition leads to a smoothing of the film surface, and also provides a strong change in the band structure and optical properties.

The change of the immitance of the metal–insulator–metal memristive structures based on SiOx, which is observed during electroforming and resistive switching, confirms the formation of conducting channels (filaments) in the insulator during forming and their rupture upon a transition of the structure to a highresistance state. The observed switching of the differential capacitance and conductivity synchronously with the switching of current (resistance) can substantially extend the functional applications of memristive devices of this type.

We have studied Au/SiOx/TiN/Ti memristive structures obtained by magnetron sputtering, which exhibit a reproducible resistive switching effect. The influence of the thickness and stoichiometry of SiOx layer and the area of Au electrode on the parameters of switching has been analyzed. The obtained results show evidence in favor of the filament model of resistive switching in SiOx films.

The composition and structure of silicon surface layers subjected to combined gallium and nitrogen ion implantation with subsequent annealing have been studied by the X-ray photoelectron spectroscopy, Rutherford backscattering, electron spin resonance, Raman spectroscopy, and transmission electron microscopy techniques. A slight redistribution of the implanted atoms before annealing and their substantial migration towards the surface during annealing depending on the sequence of implantations are observed. It is found that about 2% of atoms of the implanted layer are replaced with gallium bonded to nitrogen; however, it is impossible to detect the gallium-nitride phase. At the same time, gallium-enriched inclusions containing ∼25 at % of gallium are detected as candidates for the further synthesis of gallium-nitride inclusions.

Transmission electron-microscopy examination revealed the appearance of a hexagonal silicon (9R polytype) inclusions in the subsrface silicon layer upon ion implantation and subsequent heat treatment of the SiO2/Si structure. The formation of this hexagonal phase is stimulated by mechanical stresses arising in the heterophase system in the course of ion implantation.

This article presents an algorithm and mathematical model for an identifying flaming combustion automated process by an unmanned aerial vehicle. A digital image processed by software filters serves as a resource about an accident and fire at oil and gas industry facilities. The algorithm deals with the aircraft height, the movement speed relative to the observation point, as well as relative to the surface background, the combustion source brightness and the investigated area flicker frequency. The generated mathematical model allows to detect a fire hazard by a drone without operator intervention.

The article presents an original solution to the problem of fire hazard indicators of oil products determining using molecular descriptors and artificial neural networks. The modelling of the forecasting process was carried out on the basis of a neural network training algorithm with a teacher and an error back propagation algorithm. The resulting model makes it possible to determine the fire hazard properties of substances in real time without time span and other costs.

Providing comprehensive security of the pipeline is the main task of monitoring linear facilities in the oil and gas industry. Proposed mathematical model is a part of an automated identification algorithm to determine the fire load type. The study identified four groups of combustible substances characteristic of oil and gas facilities: oil, refined products, liquefied petroleum gas and vegetation. There was a study of electromagnetic radiation of the optical range, recorded by an UAV’S digital camera for each type of substance. An algorithm for comparing the area color with a standard was proposed and implemented. The obtained mathematical correspondence allows identifying the fire color and the fire load type in conditions of different luminosity. The information on the flaming substance allows authorized rescue units to make operational decisions about the fire extinguishing method.

Recent advances in nanophotonics are due to the implication of new approaches to the photonic devices and components design, not only related to structural features, such as subwavelength periodic arrangements, but also new materials, e.g., phase-change materials like GeSbTe (GST) alloys. We consider recently proposed optical non-volatile GST memory cell with a GST diffraction grating instead of a continuous film placed on a silicon nitride waveguide. The grating allows diminishing the energy budget of an incident electromagnetic beam in case of an optically induced phase transition of GST due to excitation of the resonant guided mode in the grating. The excitation of this mode results in anomalous reflectance spectra of the waveguide-grating structure. Here, we present the reflection spectra of GST diffraction gratings on a silicon nitride waveguide calculated with the use of the matrix Riccati equation technique in the theory of multiple electromagnetic wave scattering in inhomogeneous media. We show how the reflection changes with variation of different parameters – grating period and height, incident wave polarization, and phase of the GST film.

The search of ways to improve light-emitting properties of silicon is of great importance for modern optoelectronics. In this work, the photoluminescence (PL) properties of the band at λ = 1235 nm, which appears in silicon upon irradiation of the SiO2/Si system with Kr+ ions followed by annealing at 800 °C, have been studied. It is assumed that the source of PL is a 9R-Si hexagonal phase formed in Si substrate at the interface with SiO2 film. An interpretation is given for the established PL regularities that include the dependencies of PL band intensity on temperature and laser excitation power, as well as the temperature dependence of spectral position of the band maximum.

An original approach has been presented to model the regularities and parameters of resistive switching based on the kinetic Monte Carlo (kMС) 3D simulation of stochastic migration of oxygen vacancies/ions in metal-oxide memristive devices promising for applications in emerging nonvolatile memory, in-memory and neuromorphic computing systems. The efficiency and flexibility of the approach is demonstrated by the examples of experimentally realized Au/oxide/TiN memristive device structures, in which yttria-stabilized zirconia (ZrO2(Y)) polycrystalline films and amorphous SiO x columnar films obtained by magnetron sputtering are used as the switching oxide material. The proposed approach combines the universal kMС framework for ion migration and relatively simple physics-based methods for taking into account additional factors related to the structure and morphology of specific oxide material, interface phenomena and energetics of electronic processes, and therefore does not require time-consuming calculations and is not critical to the computing power.

The development of artificial intelligence systems is needed to solve many important challenges in neurobiology and neuroengineering for recreation of brain functions and efficient biorobotics. Here we propose a metal-oxide memristive device compatible with CMOS technology and suitable for hardware implementation of neuromorphic tasks. However, metal-oxide memristors have a significant drawback such as variation of resistive switching parameters due to the stochastic nature of filament formation in oxide material. In this work, we control the filament formation process by irradiation of oxide film surface with heavy ions. We have shown that the irradiation of oxide surface in the Au/SiO2/TiN memristive device with Xe+ ions (at energy of 5 keV) decreases the fluctuations of electroforming voltage, current-voltage characteristics during switching and increases the current ratio in the high/low resistance states. The ability to control internal parameters of the memristor can allow more efficiently using memristor as an element of neural networks and other neuromorphic circuits.

The regularities of ion synthesis of dislocation-related luminescence centers in silicon have been investigated. By varying the conditions of additional irradiation with boron ions, as well as the conditions of subsequent annealing, we obtain an increase in the luminescence intensity, as well as a shift of maximum of the temperature dependence towards higher temperatures. It was found for the first time that, for the highest used dose of boron ions (3·1017 cm-2) and additional heat treatment at 830 °C, it is possible to get the measurable luminescence at room temperature.

The effect of irradiation with H+ and Ne+ ions with an energy of 150 keV on memristive Au/SiO x /TiN/Ti structures, which were obtained by magnetron sputtering and exhibited a reproducible resistive switching effect, is studied. It is demonstrated that the low and high resistance states remain unchanged up to a dose of 1 × 1016 cm–2 in the case of irradiation with H+ ions and a dose of ~3 × 1015 cm–2 under irradiation with Ne+ ions. The obtained results demonstrate the high tolerance of parameters of the studied memristive structures to both ionizing radiation and displacement damage.

A simple and rapid method has been proposed for the determination of 1–25 μg/kg of diethylstilbestrol and β-adrenostimulator ractopamine in food by gas-liquid chromatography with an electron-capture detector. The extraction of the target components was performed by the QuEChERS method; the additional purification of the extract and preconcentration in the determination of diethylstilbestrol has been performed by dispersion liquid-liquid microextraction with tetrachloromethane. Recovery was 92–110% and preconcentration factor, 40. The time of analysis is 1.5–2 h; the relative standard deviation of the results of analysis does not exceed 10 %.

The depth distribution of light-emitting centers of the D1 dislocation-related photoluminescence line (∼ 1.5 μm) in silicon implanted with Si+ ions and annealed at 1100 °C in the oxidizing chlorine-containing atmosphere has been investigated by means of the layer-by-layer chemical etching. It is established with the application of cross-sectional transmission electron microscopy that the main contribution to the D1 line is made by the centers located at the depths of up to ∼ 150 nm, i.e. in the region of Si+ ion ranges, whereas the dislocations produced by Si+ implantation and annealing at 1100 °C penetrate to the depth of ∼ 1000 nm. Additional boron ion doping with subsequent annealing at 800 °C in N2 atmosphere improves the emission in comparison with the undoped but annealed reference sample, however the additional annealing at 800 °C per se results in the photoluminescence weakening. The dependence of the D1 line intensity on boron ion dose is found to be nonmonotonous. The interpretation of the obtained results is given in relation to the key role of selfinterstitials and boron impurity in the formation of radiative and nonradiative centers. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The formation of a topological structure in thin films of the high-temperature superconductor YBa2Cu3O7–δ (YBCO) using ion implantation is studied. The crystal structure and electrical properties of the initial film and the formed insulating regions are investigated. The critical temperature and critical current are measured for microbridges with a width of 3–50 μm fabricated by ion implantation. The results indicate the effectiveness of the ion-implantation method for manufacturing topological structures in YBCO films.

3D Monte-Carlo algorithm and computer code have been developed that allows choosing and optimizing the conditions of ion irradiation needed for the adequate ion-beam simulation of radiation damage under fast neutron irradiation. It is established that, by the proper selection of energy and dose of Si+ ions, it is possible to reproduce well the effect of irradiation with fission neutrons of subsurface and buried layers of silicon or Si-based 2D and 3D-heterostructures. The results can be used for testing the radiation hardness of silicon-based electronic and optoelectronic device structures.

Using transmission electron microscopy and elemental analysis, it has been shown that tungsten telluride glass (TTG) containing erbium and ytterbium as impurities penetrates into pores of porous silicon (PS) when melted in vacuum at 500°C. It has been found that the intensity of photoluminescence (PL) of erbium at the wavelength of 1.54 μm in PS: TTG layers increases by a factor of up to 5 in the layers irradiated by P+ and Ar+ ions. This is assigned to ion mixing which favors interaction among the Er ions and PS-embedded Si nanocrystals initiating sensitization of the PL, as well as to broadening of the glass-impregnated PS region. Implantation of the lighter Ne+ ions affects only weakly the PL of erbium ions.

The study is concerned with the effect of the additional implantation of Si samples with C+, O+, B+, P+, and Ge+ impurity ions followed by annealing at 800°C on the behavior of the dislocation photoluminescence line D1, induced in the samples by implantation with Si+ ions at a stabilized temperature followed by annealing in an oxidizing Cl-containing atmosphere. It is established that the intensity of the D1 line strongly depends on the type of incorporated atoms and the dose of additional implantation. An increase in the D1 line intensity is observed upon implantation with oxygen and boron; at the same time, in other cases, the D1 luminescence line is found to be quenched. The mechanisms of such behavior, specifically, the role of oxygen and its interaction with implanted impurities are discussed.

An array of cross-point memristive devices has been implemented on the basis of yttria-stabilized zirconia thin film for applications in prototypes of spiking neural networks. The resistive switching phenomena and the plasticity nature of such memristive devices are studied. Reproducible bipolar resistive switching and precise tuning of resistive state are demonstrated and used to implement the plasticity rule according to STDP (spike-timing-dependent plasticity) mechanism. STDP learning is found to be dependent on the memristor's initial resistive state value and discussed in terms of the finite conductance change in studied structures. Obtained results provide the foundation for autonomous neuromorphic circuits with unsupervised learning development.

The photoluminescence spectra of erbium centers in SiO2 films with ion-synthesized silicon nanoclusters under nonresonant excitation were investigated. Erbium was introduced into thermal SiO2 films by ion implantation. The dependences of photoluminescence intensity on the dose, the order of ion implantation of Si and Er, the annealing temperature, and additional Ar+ and P+ ion irradiation regimes, i.e., factors determining the influence of radiation damage and doping on sensitization of erbium luminescence by silicon nanoclusters, were determined. It was found that the sensitization effect and its amplification due to doping with phosphorus are most pronounced under the conditions where nanoclusters are amorphous. The quenching of photoluminescence due to radiation damage in this case manifests itself to a lesser extent than for crystalline nanoclusters. The role of various factors in the observed regularities was discussed in the framework of the existing concepts of the mechanisms of light emission and energy exchange in the system of silicon nanoclusters and erbium centers.

An express method was developed for the simultaneous identification of bisphenol A, diethylstilbestrol, hexestrol, and dienestrol in canned foods, drinking water, and alcoholic and nonalcoholic beverages by gas-liquid chromatography with ECD and mass spectrometry detectors. Target compounds were extracted from foods with acetonitrile using QuEChERS method. Additional purification and concentration of the extract was carried out using dispersive liquid-liquid microextraction with carbon tetrachloride. These compounds were converted into the volatile derivatives with trifluoroacetic anhydride. Concentration range was 0.5–100 μg/kg. The identification of stilbene derivatives was carried out based on mass spectra. The duration of the analysis was 1–1.5 h, and the relative standard deviation of the analysis does not exceed 0.1.

It has been shown that traditional diagnostic methods associated with the solution of inverse problems described by Fredholm integral equation of the 1st kind from a mathematical point of view, are failure, because they do not take into account their ill posed problems. The ill posed problems is connected c on the one hand with the ambiguity of the inverse problem solution and on the other hand with a huge quantity of a matrix of transition from the experimental results to the desired values. Proposed diagnostic method associated with functional Tikhonov minimization. Monte Carlo method the convergence to the exact solution with an error of initial information tends to zero. The practical results of applying the proposed method for the diagnosis of the distribution function in the emission, plasma, solid and nano-electronics.