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The aim of this work is a comparative analysis of the biocidal efficiency of Ag nanoparticles (NPs) in the colloidal state, in the structure of films and dispersions of SiO2 and in the composition of textile fabrics, dependent on the method of synthesis, based on literature data and on own researches. Chemical reduction of silver (with borohydrides, hydrogen, hydrazine, etc.) allows one to adjust and control the size and shape of NPs. The shape of the NPs is mostly spherical, what is confirmed by the presence of a band of surface plasmon resonance in absorption spectra and by electron microscopy measurements. To prevent aggregation of NPs obtained by the method of chemical reduction in solution, the optimal ratio of two stabilizers based on surfactants and polymer at their minimum concentration was found, namely NaBH4 as a reductant and polyvinylpyrrolidone + sodium dodecyl sulfate as binary stabilizer of Ag NPs, with bactericidal activity of 99 % and stability for more than 3 years. Chemical reduction of silver ions was carried out also by the amino acid tryptophan (Trp) which has a dual function – a biocompatible reducing agent and stabilizer of silver NPs while maintaining their shape, size and stability for long-term use. Effective methods of photochemical synthesis of Ag NPs have been developed in different ways: by UV irradiation of Ag+ ions in solution in the presence of solid-state photosensitizer SiO2 with adsorbed benzophenone (SiO2/BPh); by UV irradiation of Ag+ ions in solution in the presence of the amino acid tryptophan (Trp); on silica surface when Ag/SiO2 sol-gel films production via irradiation of adsorbed Ag+ ions on SiO2 film (Ag+/SiO2) in the BPh solution. It is shown that when Ag NPs are adsorbed on the surface of highly dispersed SiO2, the logarithm of the reduction of microorganisms reduces and the time of their deactivation increases. A cheap and convenient way to modify of cotton textiles with Ag NPs by soft heat treatment of Ag+/cotton samples with high (90–95 %) efficiency of destruction of bacteria E. coli, K. pneumoniae, E. aerogenes, P. vulgaris, S. aureus, C. albicans, etc., with saving of biocidal activity after 5 cycles of washing has been developed. The dynamics of silver ions release from the surface of NPs in the structure of textile upon their contact with water for 72 hours and the number of irreversibly bound particles have been studied. The electrical resistance of the tissue is proportional to the quantity of NPs. That is NPs in the structure are in different degrees of binding, a certain part of them is retained (adsorbed) irreversibly, saving bactericidal properties after repeated contacts with water. On the basis of literature analysis it is shown that ecologically safe “green synthesis” is a promising way to silver NPs produce with pronounced bactericidal efficiency, which is becoming more common due to the large resource of cheap plant raw materials.

Abstract In this review of experimental studies, the retention time and endurance of memristor RRAM memory elements based on reversible resistive switching in oxide dielectrics are studied. The influence of external parameters—switching pulses and ambient temperature—as well as internal factors—evolution of the concentration of oxygen vacancies in the filament region, the material, structure; the thickness of the active dielectric layer, material of metal electrodes on the long-term stability of high resistance state (HRS) and the low resistance state (LRS) of the memristor is discussed.

The selectivity of the reactive ion etching of functional materials included in the device structures of nanoelectronics with respect to the mask of a negative e-beam resist based on hydrogen-silsesquioxane (HSQ) is studied. The formation of nanostructures with sub-50-nm critical dimensions under the HSQ mask is studied for a number of materials: monocrystalline silicon, metallic Ta layers, dielectric SiO2 layers, Al2O3, HfO2, Si3N4, and low-k porous dielectric based on organosilicate glass (OSG) on silicon substrates. It is established that HSQ resist masks can be used to manufacture prototypes of micro- and nanoelectronic devices with topological dimensions up to 10 nanometers using a wide range of materials, including creating structures with relatively high aspect ratios with an absolute thickness of the layers of functional materials of tens of nanometers.

The stress state of the surface layer in the contact zone of the mating teeth of cylindrical gears is considered. It is shown that under contact loading, the stress state of the surface layer is inhomogeneous and changes with the distance from the surface. It is established that the value of the equivalent tangential stresses does not depend on the standard size of the gears, but is determined by the surface contact stresses σH. Moreover, the depth of occurrence of the maximum equivalent tangential stresses depends on the gear modulus (the reduced radius of curvature of the mating surfaces of the teeth) and, to a lesser extent, on the surface contact stresses σH. The inhomogeneity of the stress state and the structural characteristics of the diffusion layers of surface-hardened gears is a prerequisite for the appearance of critical zones in them, in which fatigue processes of contact failure can originate and develop. A deterministic analytical model of the resistance to deep contact fatigue of hardened tooth surfaces is proposed, based on determining the service life of the gear before the appearance of progressive deep contact chipping of the active tooth surfaces with a regulated variation of the microhardness values in different zones of the diffusion layer.

The phase equilibria in the NaF–AlF3–CaF2 system with a fixed sodium-fluoride-to-aluminum fluoride molar ratio of 1.17 are studied. This composition is eutectic; its melting temperature is 680°C. Samples were prepared using individual salts. Aluminum fluoride is purified from oxygen-containing impurities using ammonium fluoride and glassy carbon crucible. The study is performed by thermal analysis, differential scanning calorimetry (DSC), and X-ray diffraction (XRD). To perform XRD and DSC analyses, the melt is frozen on an alumina stick in order to prepare quenched samples. The liquidus temperatures are determined by measuring cooling curves, which are plotted on the thermopower–time coordinates using an APPA 502 multimeter. The solidus temperatures were studied with a STA 449C Jupiter (NETZSCH, Germany) synchronous thermal analyzer, which is calibrated using pure salt supplied by NETZSCH. A single-crystal sapphire is used to calibrate the sensitivity. A MiniFlex 600 X-ray (Rigaku, Japan) diffractometer equipped with a copper anode is used for XRD studies to determine the phase composition of samples. A quasi-binary (NaF–AlF3)eut–CaF2 phase diagram is constructed. Seven samples are studied; in this case, the potassium fluoride content is varied from 0 to 6.5 mol %. The diagram is characterized by a eutectic point at a calcium fluoride content of 0.5 mol % and a temperature of 675°C. The phase diagram also has two peritectic points, which correspond to the decomposition of the complex Ca2AlF7 and NaCaAl2F9 compounds. When reaching the eutectic point, the liquidus temperature abruptly increases as the calcium fluoride content increases. This results in the low solubility of CaF2 in the low-melting NaF–AlF3 eutectic at temperatures below 750°C. The data obtained are of interest for developing a technology of low-temperature electrolysis of aluminum.

Mechanical properties of the metal from drums of boilers at the Starobeshevskaya and the Lugansk thermal power plants (TPPs) were investigated. According to the results of the standard technical diagnostics and a strength analysis, both drums comply with the applicable regulatory requirements. At the Starobeshevskaya TPP, the drum was ruptured during a hydraulic test. It was found that this was caused by the low impact strength of the metal at room temperature. The objects of the investigation were fragments of the ruptured drum and a “plug” cut out of the shell during a scheduled inspection. An attempt is made in this paper to assess the state of equipment metal based on the results of tests on subsize Charpy specimens. It has been demonstrated that when standard Charpy specimens (10 × 10 × 55 mm) cannot be made but impact bend tests have to be performed, the brittle-to-ductile transition temperatures for standard Charpy specimens may be obtained in testing 2 × 8 × 55 mm specimens. The correlation developed to relate the test results from subsize specimens to standard Charpy specimen enables us to assess in the first approximation the fitness for service of the metal to prolong the equipment’s service life. The rupture surface of subsize Charpy specimens has almost the same appearance as that of standard specimens. The temperature dependence of ductile component of subsize specimens agrees well with the corresponding dependence for standard Charpy specimens. To integrate the test data into a single database, it is desirable to derive a correlation to relate the critical brittleness temperature from a subsize specimen test to the critical brittle temperature from standard Charpy specimens.

Optimization of complex shrinkage-reducing additives (further, SRA’s), consisting of ordinary portland cement clinker (further, OPC clinker), salt-electrolyte and surfactants, is provided for prevention of steel reinforcement corrosion due to shrinkage mitigation in alkali-activated slag cement (further, AASC) fine concrete. Modification of AASC by SRA included 0.3 % sodium lignosulphonate, 0.15 % sodium gluconate, 1.4 – 2.0 % NaNO3 and 6.5 - 7.7 % OPC clinker (by mass of granulated blast furnace slag) provides shrinkage reduction from 0.984 up to 0.560 – 0.605 mm/m (t=202 °С, R.H.=65 %). Unlike, SRA presented by the mentioned system with 1.50 - 1.59 % Na2SO4 and 4.0 - 4.65 % OPC clinker causes shrinkage mitigation from down to 0.625 - 0.640 mm/m. In addition, SRA with 1.80 - 2.05 % Na3PO4 and 4.0 - 4.6 % OPC clinker minimizes shrinkage to 0.713 - 0.700 mm/m. Shrinkage mitigation in modified AASC fine concrete is explained by less water, higher crystallinity of hydrated phases as well as by formation of minamiit (Na,Ca0.5)Al3(SO4)2(OH)6, calcium hydronitroaluminate ЗСаО∙А12О3∙Са (NO3)2∙10Н2О and calcium hydroxylapatite Са10(РО4)6(ОН)2 crystals versus salt-electrolyte, i.e. Na2SO4, NaNO3 and Na3PO4 agreeably. The 28 day compressive strength of modified AASC fine concrete is not less than the reference one (48.0 - 56.0 МPа).

Solar and hydrogen energy play an important role in providing a variety of industrial facilities with electricity and heat. One of the priorities of modern industry is to increase the production of environmentally friendly energy source – electrochemical synthesis of hydrogen. Modern methods of electrolysis of water do not meet the need for its use, due to the high cost of electrosynthesis of water-alkaline electrolysis, which depends on the material and energy consumption of electrolysis. The useful energy consumption for the production of energy – hydrogen at the cathode and "unnecessary" costs - for the release of oxygen at the anode, depend on the overvoltage of the respective reactions. Therefore, the most important problem of hydrogen energy is the synthesis of electrode materials with low overvoltage of O2 and H2. Electrode materials with low overvoltage will reduce the specific consumption of electricity in obtaining hydrogen by "classical" electrolysis. The prospects of reducing the cathodic and anodic overvoltage, which is a significant part of the voltage at the terminals of the cell, for the development of highly efficient and competitive technologies for hydrogen production by low-temperature electrolysis of an alkaline solution have been theoretically substantiated and experimentally confirmed. To reduce the overvoltage of the cathodic hydrogen evolution, it is proposed to modify the surface of the cathodes. The application of a small amount of electrolytic alloys of metals of the iron family with molybdenum and tungsten on nickel, cobalt, titanium and steel electrodes significantly (by 40–50 %) reduces the overvoltage of cathodic release of hydrogen from alkali solution. The use of steel electrodes, the surface of which is modified with vanadium and ni-ckel, reduces the voltage drop on the cell during the synthesis of H2 and O2 by 0.2–0.3 V, which creates conditions for reducing energy costs and energy savings., Сонячна та воднева енергетика відіграють важливу роль в забезпеченні різноманітних об’єктів промисловості електричною та тепловою енергією. Одним з пріоритетних напрямів сучасної промисловості є зростання об’ємів виробництва екологічно-безпечного джерела енергії – електрохімічного синтезу водню. Сучасні методи електролізу води не задовольняють потреби в його використанні, через високу собівартість електросинтезу водно-лужного електролізу, яка залежить від матеріало- та енергоємності електролізу. Корисні витрати електроенергії для отримання енергоносія – водню на катоді і "непотрібні" витрати - на виділення кисню на аноді, залежать від перенапруги відповідних реакцій. Тому найважливішою проблемою водневої енергетики є синтез електродних матеріалів з малим перенапруженням виділення О2 і Н2. Електродні матеріали з низькою перенапругою дозволять зменшити питомі витрати електроенергії при отриманні водню "класичним" електролізом. Теоретично обґрунтовано та експериментально підтверджено перспективність зниження катодної і анодної перенапруги, яка становить значну частину напруги на клемах електролізера, для розробки високоефективних і конкурентоспроможних технологій отримання водню низькотемпературним електролізом лужного розчину. Для зниження перенапруги катодного виділення водню запропоновано модифікувати поверхню катодів. Нанесення незначної кількості електролітичних сплавів металів сімейства заліза з молібденом і вольфрамом на нікелеві, кобальтові, титанові і сталеві електроди суттєво (на 40–50 %) знижує перенапругу катодного виділення на них водню з розчину лугу. Використання сталевих електродів, поверхня яких модифікована ванадієм і кобальтом, дозволяє знизити падіння напругу на електролізері при електросинтезі Н2 і О2 на 0,2–0,3 В, що створює умови зниження енергетичних витрат і економії електроенергії.

Using the method of quantum-chemical modeling of a system of gold nanoparticles on a graphite substrate with various defects, a decrease in the density of states of gold atoms during the adsorption of hydrogen near the interface is shown. Substrate defects, such as vacancies and cutoffs of the graphene plane, contribute to a decrease in the density of states during the adsorption of hydrogen atoms.

The effect of blood adhesion on the amplitude-frequency characteristics of a piezoelectric sensor in the method of low-frequency piezothromboelastography is studied. As a result of adhesion, a layer of blood cells can accumulate on the surface of the resonator needle immersed in blood, which changes its configuration and mass and, as a consequence, its amplitude-frequency characteristics. Experiments showed that during coagulation, the free frequency of the resonator needle oscillations decreases in direct proportion to the increase in the mass of adhered blood. To confirm this regularity, we carried out a numerical experiment on the basis of 3D-mathematical model of a piezoelectric sensor used in the piezotromboelastograph ARP-01M Mednord. The experiment was performed with the help of the COMSOL Multiphysics® 4.2 software package and the finite element method. We calculated the change in the free frequency of the resonator needle oscillations as a function of the adhered blood mass and their time dependence in the blood coagulation process. It is shown that during coagulation, the mass of adhered blood increases starting from the third minute and reaches its maximum of 0.42 milligram in 15 minutes, which leads to a noticeable shift in the resonance frequency of the piezoelectric sensor towards lower frequencies.

Complex oxides with pronounced proton transfer occupy a special place in modern solid-state ionics and high-temperature electrochemistry, being of great interest from both fundamental and applied viewpoints. Doped barium cerate-zirconates (BaCeO3–BaZrO3) are positioned as the most conductive oxides, and therefore they are widely used in various solid oxide devices. However, the presence of a highly basic alkaline earth cation leads to an insufficient chemical stability of cerate-zirconates in real working conditions. In this regard, designing new proton-conducting oxides with improved chemical stability is an actual issue. Some lanthanum-containing perovskites, LaBO3 (where B is a trivalent element), can be considered as stable analogs since they contain no alkaline and alkaline earth elements in their basic structures. This review aims at a critical analysis of the properties of these compounds and the prospects for their application as electrolyte membranes for solid oxide fuel cells, pumps, and sensors. The paper provides basic information about LaBO3-based compounds, highlights their advantages in comparison with other representatives of proton conductors, and indicates disadvantages acting as limiting factors for the application of lanthanum-containing protonic electrolytes with a perovskite structure in electrochemical devices.

A method of obtaining detonation nanodiamonds from tetryl by means of blasting the latter in a water shell with the explosive/water mass ratio of 1/(10–14) is developed. The proposed method ensures the yield of the target product in the amount of 6–7 wt.% of the initial mass of the reagent with the content of nanodiamonds in the resultant batch mixture equal to 57 $$\,\pm\,$$ 6 wt.%. It is demonstrated that the use of individual explosives offers some advantages over the known multicomponent mixtures in terms of cost efficiency and safety of the charge preparation process.

The (CsCl–NaCl–KCl)eut–IrCl3 melt is promising for the production of iridium coatings and composites. The liquid temperature and the electrical conductivity are determined for several compositions of the melt by thermal analysis and impedance spectroscopy. The temperature ranges of liquidus (753–983) ± 5 K and solidus (751–755) ± 4 K are established and the corresponding parts of the phase diagram for the quasi-binary system (CsCl–NaCl–KCl)eut–(0–2.12 mol %) IrCl3 is plotted. The lowest liquidus temperature is shown to be observed for the melt containing 1.4 mol % IrCl3. The increase in the liquidus temperature in the molten mixtures with more than 1.5 mol % IrCl3 is explained by the formation of the Cs3IrCl6 compound, which was detected by XRD analysis. The electrical conductivity of the melts (in the homogeneity region) is found to linearly decrease as the temperature decreases or the IrCl3 concentration increases. The coefficients that describe the temperature dependences of the electrical conductivity of the (CsCl–NaCl–KCl)eut–(0–2.12 mol %) IrCl3 melts are determined. For all the studied iridium-containing compositions, the average temperature coefficient is (2.35 ± 0.02) × 10–3 Ω–1 cm–1 K–1. The addition of 1 mol % IrCl3 leads to a decrease in the electric conductivity by about 7%. It is found that the operating temperature can be decreased to ~800 K in the melt with iridium trichloride concentrations of 1.4–1.5 mol %; the process temperature can be varied from 850 K to 1030 K at lower and higher IrCl3 contents depending on the electrodeposition conditions.

Mossbauer spectroscopy is used to study the characteristic features of the crystal lattice dynamics in powdered single crystals of Fe1.75V0.25BO4 warwickite in the temperature range of 4.2–505 K. The Debye temperature (ΘD = 260 K) is determined from the temperature dependence of the probability of the Mossbauer effect in the thin absorber approximation. It is found that the electron delocalization related to the fast electronic transfer between neighboring Fe3+ and Fe2+ cations takes place in the temperature range of 260−505 K. As a result, iron cations exhibiting the mixed valence (Fe2.5+) arise. This process correlates with a change in the elastic properties of the lattice. Such correlation leads to a sharp decrease in the recoil-free absorption of γ‑ray photons by the crystal lattice in the range of 260–400 K.

During storage, confectionery products of a gelatinous consistency are subject mainly to physical changes, such as staleness or moisture, however, there are some cases of their "mold" or fermentation, which are caused by moisture transfer processes, and the driving force is the gradient of water activity. The rate of transition of water from one phase to another depends on the difference between the equilibrium and working concentrations, the physical properties of the system and the "hydrodynamic setting" of the process. The relationship between the factors is established using the equations of diffuse kinetics. The influence of various factors on the processes of moisture transfer of confectionery products of a jelly-like consistency was investigated using the example of jelly-fruit marmalade. It is shown that an increase in storage temperature by 10 °C leads to an increase in the rate of moisture transfer of jelly-fruit marmalade, made without the use of modified starch, by a factor of 2.2. The use of 2% different types of modified starch allows to reduce the rate of moisture transfer of jelly-fruit marmalade by 1.3–1.7 times. The use of modified starch E1412 reduces the rate of moisture transfer by 1.7 times as compared to the control sample of marmalade without the addition of modified starch. The use of modified starch E1401 in the manufacture of jelly marmalade predicts an increase in the preservation of products (no "crust" during storage). To predict moisture loss during storage of confectionery products of a gelatinous consistency, it is proposed to use the molecular diffusion coefficient, which allows to substantiate the type of structurant, the thickness of the packaging used and the storage temperature of products with a given shelf life. The molecular diffusion coefficient of jelly-fruit marmalade ranges from 0.56 ? 10-13 m2/s to 2.04 ? 10-13 m2/s. The maximum coefficient corresponds to the highest rate of moisture transfer processes.

The mid-infrared (IR)-sensitive n/p-junction was fabricated on a p-doped silicon (Si) wafer via ultrashort laser n-type surface hyperdoping and high-temperature annealing. First, the n-type sulfur ...

We investigate the fragmentation and isomerization of toluene molecules induced by strong-field ionization with a femtosecond near-infrared laser pulse. Momentum-resolved coincidence time-of-flight ion mass spectrometry is used to determine the relative yield of different ionic products and fragmentation channels as a function of laser intensity. Ultrafast electron diffraction is used to capture the structure of the ions formed on a picosecond time scale by comparing the diffraction signal with theoretical predictions. Through the combination of the two measurements and theory, we are able to determine the main fragmentation channels and to distinguish between ions with identical mass but different structures. In addition, our diffraction measurements show that the independent atom model, which is widely used to analyze electron diffraction patterns, is not a good approximation for diffraction from ions. We show that the diffraction data is in very good agreement with ab initio scattering calculations.

A numerical model of the evolution of the trench profile during cryogenic etching in SF6/O2 plasma based on the cellular representation of the surface state, the Monte Carlo method for calculating particle fluxes, and the scheme of delayed desorption of reaction products is proposed. This description combines the advantages of the cell method (the ability to describe phenomena of a stochastic nature) and the string method (parameterization of the model in terms of physically observable quantities). The consistency of the model for etching silicon and silicon oxide in a fluorine-containing plasma, as well as etching in a SF6/O2 mixture at different temperatures is demonstrated. Spontaneous etching of silicon under the action of fluorine radicals, ion-stimulated etching, surface passivation in plasma containing oxygen radicals are simulated. A model that describes the temperature dependence of the etching character is proposed.

Highly efficient stable aerated hydrophilic compositions containing fluorotensides and ultralight microdisperse systems using gas-filled glass, aluminosilicate and polymer microspheres have been developed. Designing the compositions of PAS based on the surface activity of surfactants, their solubility in water and the ability to bind water and the formation of hydrogen bonds between the components. The main condition for the stability of the coating when mixing the components - the chemical interaction between them and the formation of a system that does not dissolve in hydrocarbons and does not break down in terms of use. The best film-forming characteristics necessary for the operation of the coating (simultaneous reduction of surface tension and film formation) active substances (FPAR), the non-polar part of the molecules of which contains a fluorocarbon chain, so they are insoluble in hydrocarbons, well soluble in water and easily distributed on the surface of hydrocarbon liquids, creating a protective film. The choice of co-surfactants was based on the ability to stabilize hydrophilic films on the surface of hydrocarbons not only at favorable HLB, but also at the lowest, although higher than the critical concentration of micelle formation (CCM), concentrations for forming a mixed adsorption layer of increased strength. This surfactant was water-oil-soluble twin-80, which will significantly increase the hydrophilic part and enhance the stability of the PAS and the stability of the aerated system. The introduction of glass microspheres into the components of the system has significantly enhanced its strength and stability. In the study of the stability and gas permeability of the developed surfactant systems, it was found that the insulating ability of the coating increases with increasing hydrophilic-lipophilic balance of the system and due to chemical interaction between the carboxyl group of fluorotenside and hydroxyl groups of surfactants.

The aim of the study is to create a theoretical basis that allows to calculate the forces of hot plastic deformation of the piston pin. One of the promising methods of restoring the piston fingers of the connecting rod - piston group of internal combustion engines is the method of hot plastic deformation. The process of restoring the piston fingers by hot plastic deformation can increase their strength and, in particular, fatigue strength. When developing the technological process of restoration of piston fingers using the method of hot plastic deformation by distributing it with a punch in the stamp, there is a problem of determining the effort required for high-quality deformation process. The article offers the theoretical basis for calculating the deformation forces. The result was obtained on the basis of the selected scheme of formation. As a result of the calculations we can conclude: 1. Restoration of the piston finger by hot plastic deformation allows to restore 95% of the fingers which have arrived in repair. 2. Piston fingers restored by hot plastic deformation in their technical parameters are not inferior to the new, achieved - "healing" of microcracks, creating internal compressive stresses, and grinding grain, which strengthens the material of the piston finger, in particular increasing its fatigue strength by 15… 20% . 3. As a result of theoretical studies of the resistance of the metal to plastic deformation were obtained dependences of the specific force on the punch depending on the ratio of the diameters of the workpiece.

The paper presents the features of the synthesis of hydrogen released as a result of dissolution of the aluminum alloy AMg. To more fully determine the technological characteristics of hydrogen synthesis, we studied the volumes of hydrogen released in the reactor as a result of dissolution of the aluminum alloy AMg. The mechanism of alloy dissolution is established taking into account the effect of impurities in the alloy on the anodic dissolution process. The conditions for accelerating the anodic dissolution of the AMg alloy in the presence of chlorine ions under the conditions of the “negative differential effect” are determined. The dissolution of the AMg alloy in an alkaline chloride solution has an electrochemical nature, which is based on the electrochemical mechanism of hydrogen reduction with the subsequent process of its diffusion into the gas phase. Chloride ions accelerate the active dissolution of aluminum at current densities of 5 A/dm2 instead of 3 A/dm2 at room temperature and surface roughness of class 3-5 (≈5 μm). The greatest influence on the dissolution rate of the alloy has the concentration of NaOH, the dissolution temperature and the surface cleanliness class. The main technological indicator of the improvement of hydrogen electrosynthesis is the use of anodic depolarization of aluminum, its negative values and, as a consequence, the evolution of hydrogen on both electrodes. The depolarization effect is achieved by dissolving the aluminum alloy instead of the oxygen evolution reaction at the anode. The voltage on the cell is 2 times lower compared to industrial alkaline water electrolysis. This makes it possible to save up to 50% of electricity. The absence of oxygen evolution makes this process safer.

The results of the study of the morphology and surface topography of chitosan films of the salt (S-) and basic (B-) chemical form by atomic force microscopy are presented. The films were cast from polymer solutions in acetic, lactic, citric and succinic acid. NaOH and triethanolamine were used for the salt → chitosan base reaction. Surface tomograms were obtained; the main morphological characteristics and roughness parameters of the film samples were estimated. It was found that the morphology, the degree of order, root-mean-square roughness and the height of the surface roughness were determined by the polymer chemical form, the nature of the acid used and the reagent of the polymer-like conversion reaction. The surface of the S-form chitosan films is characterized by fibrillar structural ordering (also dendritic for chitosan succinate), and that of the B-form is globular. The smallest size of surface supramolecular elements was observed for the S-form chitosan films, while the greatest roughness was for the B-form ones. Changing the reagent of the chitosan S → B reaction did not affect the morphological characteristics of the films; however, it affected the microrelief roughness. A more uniform basic chitosan film is formed in an organic base environment. It was suggested that the formation of fibrillar supramolecular structures was due to the unfolding and straightening of macrochains because of the repulsion of the same charged monomer units, while the globular ones were formed due to the folding and densification of macrocoils after neutralizing the total charge of the macrochain.

The contribution of magnetoelastic effects to the effective magnetic anisotropy of a three-layer film nanodisk (nonmagnetic metal/ferromagnet/nonmagnetic metal) was studied. The mechanical stresses at the lateral surface of the disk that are caused by two factors, i.e., unequal thermal expansion of layers and excess surface energy at the layers interfaces, were estimated. The case in which the contribution of magnetoelastic effects to the anisotropy is comparable with those of shape and crystalline anisotropies was discussed. It was shown that the main reason for the change in the local anisotropy field in the vicinity of a nanodisk edge was the mechanical stresses induced by the excess surface energy. The possible application of film nanodisks of nickel with a bilateral golden coating as “nanolancets” for noninvasive cell surgery of tumors was discussed.

Polarization studies of the ZrB2–SiC–AlN compact ceramic material and thermal spray coatings of the same composition were conducted in a 3% NaCl solid solution to analyze their cathodic and anodic behavior. The compact ceramic material was produced by hot pressing, the plasma-sprayed coating 240 μm thick was deposited onto a C/C–SiC graphite substrate, and the detonation-sprayed coating 340 μm thick was applied to 12Kh18N9T stainless steel. The microstructure and phase composition of the compact sample and thermal spray coatings were examined. The microstructure was heterophase in all cases. The compact sample and plasma-sprayed coating contained SiC, AlN, and ZrB2 as the main phases, and the detonation-sprayed coating additionally had a small amount of nickel and zirconium oxide. Electron microprobe analysis showed that the plasma-sprayed coating had 20 wt.% oxygen; i.e., the coating contained oxide phases in the amount not revealed by X-rays. The compact ceramic sample showed exceptionally high resistance to electrochemical oxidation: electrochemical potential, Ecorr, at which corrosion current occurs is very high and constitutes +1.51 eV. For the detonation- and plasma-sprayed coatings, Ecorr = –0.25 and –0.05 eV, respectively. The great resistance of the compact ceramic material to electrochemical oxidation correlates with its resistance to high-temperature oxidation above 1700°C. This is due to the formation of an Al2O3–SiO2 mullite film on the surface. The lower resistance of the coatings to electrochemical oxidation compared to the compact material is associated with their increased porosity.

Highly stressed transmission parts of energy-saturated machines are made of steels subjected to carburization and subsequent hardening. A low-carbon steel product forms a strong, high-carbon surface layer with a soft and viscous core. An important parameter of the hardened layer is its effective thickness hэфф. The article studies the effect of the duration of the cementation process on hэфф of samples from 18ХГТ (18KhGT) steel used for the manufacture of gear wheels of highly loaded transmissions. The possibility of using a magnetic parameter for non-destructive testing hэфф was also investigated. The device “Magnetic Sorter MS-1” was used, which measures the gradient of the normal component of the remanent magnetization field above the point of contact of the magnet pole with the metal surface. To determine hэфф, interpolation of measurements of the distribution of microhardness HV over the layer thickness on manufactured microsections was used. HV microhardness values are converted to HRC hardness values according to the dependence recommended by the international standard. Studies have shown that hэфф of the cemented layer of 18ХГТ (18KhGT) steel after quenching linearly depends on the cementation time. There is a correlation between the hэфф of the samples studied and the readings of the MS-1 device. This is a prerequisite for the development of a non-destructive method for controlling the process of chemical heat treatment of gear wheels of transmissions of mobile machines.

Silicon-on-insulator (SOI) is most promising present-day silicon technology. The use of SOI provides significant benefits over traditional bulk silicon technology in fabrication of many integrated circuits (ICs), and in particular, complementary metal-oxide-semiconductor (CMOS) ICs. It also allows extending the miniaturization of CMOS devices into the nanometer region. In this review paper, we briefly describe evolution of SOI technology and its main areas of application. The basic technological methods for fabrication of SOI wafers are presented. The principal advantages of SOI devices over bulk silicon devices are described. The types of SOI metal-oxide-semiconductor field-effect transistors (MOSFETs) and their basic electrical properties are considered.

The adsorption of hydrogen on bimetallic gold–nickel and gold–copper nanoparticles is simulated quantum chemically. We find that the changes in the adsorption properties of the bimetallic nanosystem are due to the change in distances between atoms and the redistribution of the electron density in the cluster. This leads to an increase in the bond energy of the hydrogen atom near the Ni/Cu atoms; and a decrease, near the Au atoms of the bimetal cluster.

Unique sulfur- and carbon- doped silicon nanoparticles, as well as partially oxidized, are obtained by nanosecond laser ablation of silicon in liquid carbon disulfide. Detailed structural, chemical, and optical characterization of these particles was performed by scanning and transmission electron microscopy, IR spectroscopy, energy dispersive X-ray spectroscopy, and Raman scattering spectroscopy. It is shown that the sulfur concentration in particles is on the order of 1 at %, owing to which they demonstrate a considerable absorption in the mid-IR region.

The simple lattice and magnetic structure, the high Neel temperature, the narrow antiferromagnetic resonance line of FeBO3, and the narrow electron paramagnetic resonance line of its isostructural diamagnetic analogs MBO3:Fe3+ (M = Ga, In, Sc, Lu) make iron borate unique for investigations and applications. Iron borate is a model crystal for numerous experimental and theoretical studies, including spin crossovers and metallization at megabar pressures and many-electron effects in optics and X-ray spectroscopy. The recent works dealing with the investigation of the properties of FeBO3 are reviewed.

Theoretic and experimental study of viscoelastic properties of the whole blood exposed to shear stress was carried out with acoustic resonance method based on the measurement of gain-frequency characteristics of resonating needle in an ARP-01M piezoelectric thromboelastograph (Mednord). The study revealed regularities in the changes of viscoelastic parameters of the whole blood within 0-80 kHz frequency range of shear vibrations. In this frequency range, the elastic (storage) modulus G' reflecting blood elasticity increased with frequency and significantly contributed to the complex viscosity coefficient. The revealed gain-frequency regularities open the vista to employ the acoustic resonance method to determine the viscoelastic parameters of the whole blood and their coagulation-induced changes in the wide frequency range of shear vibrations.

A study was made of the dependence of the contrast value of a negative electron resist based on hydrogen-silsesquioxane (HSQ) in the process of the development of NaOH–NaCl in an aqueous alkaline-salt solution at various temperatures. When the temperature of the developer rises from 22 to 40°C the contrast increases by 45%. An increase in contrast was also found with a decrease in the developing temperature by 27% to 10°C compared with the developing temperature of 22°C. Thus, a nonmonotonic change in the contrast of the HSQ resist from the temperature of the development was established. Studies of AFM images of test structures in areas where exposure to the HSQ resist was performed demonstrate the phase contrast even in regions with zero resist thickness after development, which indicates a change in the adhesive properties of the surface.

Evaluation of applicability of 20MnCrS5 steel for gears of transmissions of mobile machines, manufactured according to European standard EN 10084 was carried out. Experimental and virtual simulation of hardenability of the steel according to the updated method was realized. The assessment of the applicability of 20MnCrS5 case-hardening steel for gears of the domestic mobile machines was made by the criterion of obtaining the cross section of the tooth structures with a hardness 32 HRC for core, 50 HRC for semi-conversion zone, 61–63 HRC for the diffusion layer excluding other physical and mechanical properties of steel.It is established that at the content of alloying elements close to the maximum limit, the use of this steel is possible for gears with a module up to 10 mm.

A theoretical and experimental study of the viscoelastic properties of whole blood under oscillating shear stresses has been carried out. Based on ultrasonic elastography, a mathematical model and a method for calculating the complex viscosity coefficient of whole blood during its coagulation have been developed. The complex viscosity coefficient of whole blood and its real and imaginary parts were calculated. The calculated viscosity coefficient of blood at the beginning of the coagulation process is in good agreement with the data of rheometric measurements. The results obtained confirm the ability of using this approach to determine the viscoelastic properties of whole blood and analyze their dynamics during coagulation in a regime as close as possible to an in vivo study.

A theoretical and experimental study was performed of a frequency dependence of the amplitude-phase characteristics of the vestibular nerve stimulation signal and its changes during passage from the stimulating electrodes to the end of the vestibular nerve. To assess the influence of leakage currents on the change in the stimulating current pulse, a physico-mathematical model of the vestibular organ and electrical processes occurring in its tissues was developed on the basis of experimental data on electrophysical and anatomical characteristics of the vestibular labyrinth tissues by the example of a guinea pig. The calculations and measurements of the frequency dependence of the amplitude-phase characteristics of the stimulating signal at a recording electrode located in the Scarp’s ganglion are performed. It is established that the influence of leakage currents on the signal amplitude at the recording electrode is significant in the entire frequency range considered. Compensation of the influence of leakage currents will improve the stimulating signal quality and increase the transfer function of the vestibular implant.

Introduction. At present the most accurate estimate of ranges is specific to laser range finders using phase measuring techniques. Design of a pulsed laser range finder with short probe pulses enabling one to gain high resolution and accuracy of estimate of target range close to the phase range finders is the topical problem.Aim. Development of a receiving part of the pulsed laser rangefinder with precision characteristics; determination of the accuracy of the measurements; description of the hardware.Materials and methods. The construction of the receiving part of the precision pulsed laser rangefinder with a two-scale digital range estimation system implemented by counting clock generator pulses and an analog integrator that specifies the discrete range estimation was considered. Using the methods of mathematical statistics, the energy characteristics of the rangefinder were determined: the accuracy of the range estimation and the probability of false alarm were provided by the developed scheme. The hardware of the precision laser rangefinder was described.Results. The principles of implementation of the receiving part of the laser rangefinder with a two-scale digital system for estimating the distance to the object were given. The results of numerical simulation of rangefinder characteristics were obtained, confirming the accuracy of range estimation of the order of millimeters. In the implemented rangefinder scheme, the probability of false alarm was 10-4 during 200 s of observing signal and noise mixture. The hardware of the precision laser rangefinder with a digital two-scale range estimation was proposed.Conclusion. The implemented laser range finder approaches to the capabilities of phase laser rangefinders in terms of potential accuracy of distance up to millimeters, while implementing the specified parameter in rapidly changing phono-target environment. Using of short probing pulses with a duration of 10...20 ns allows one to achieve a resolution of up to 1.5 m. In contrast to the phase rangefinder the range can be estimated from a single probe pulse.

The exchange interactions in the Cr3+–Cr3+ ion pairs in the isostructural ABO3 (A = Ga, In, Sc) diamagnetic compounds have been examined using the magnetic resonance technique. The values of bilinear and biquadratic exchange interactions have been determined. It is shown that the biquadratic exchange in the Cr3+–Cr3+ pair in these compounds is caused by the exchange striction.

Study results of the effect of high-temperature vacuum chemical-thermal treatment on the grain size of structural steels possessing various chemical compositions are given. It is determined that a sufficiently large grain is formed in the 20KhN3A, 25KhGT, and 20KhNR steels during quenching directly after prequench from the carbonization temperature of 1000–1050 to 850°C, whose size exceeds acceptable limits. It is stated that the steels manufactured according to GOST 4543–2016 are inapplicable for high-temperature carbonization. The composition of new inheritable fine-grained steel is developed, which is not affected by the increase in the carbonization temperature. An increase in the carbonization temperature of new steel up to 1050°C with a double decrease in the time of treatment is demonstrated.

The solidus and liquidus temperatures and fusion heat were investigated in [(0.54NaF–0.46AlF3)eut-(0.55KF–0.45AlF3)eut]-quasi-binary system. Two maximum liquidus temperatures (~ 1000 K) were observed at KF/(KF + NaF) ratio equal to 0.15 and 0.65. The minimum liquidus temperature (~ 900 K) was observed at KF/(KF + NaF) ratio equal to 0.3. The solidus temperatures were related to complex compounds KAlF4 and K2NaAl3F12. The heat of fusion of eutectic compositions was found to be directly proportional to melting point. Thermal diffusivity of two eutectic mixtures was studied by laser flash method in temperature interval 300–800 K. Thermal conductivity was calculated using density and heat capacity data obtained for the same mixtures. Both thermal diffusivity and thermal conductivity are reduced with temperature for samples investigated. Thermal conductivity of potassium eutectic changes from 2.3 at 300 K to 1.8 W∙m−1∙K−1 773 K, and that of sodium eutectic reduces from 1.65 W∙m−1∙K−1 at 300 K to1.45 W∙m−1∙K−1 at 773 K.

An analytical scheme is proposed for monitoring the contamination of an alumina-modified silica gel adsorbent in the process of purifying natural gas with TP-22C components of turbine oil. The objects of the study were the samples of both the fresh adsorbent and the spent adsorbent in the process of purification of natural gas. The identification of turbine oil components on the adsorbents was carried out using the thin-layer chromatography on Sorbfil plates by separating the oil components on the thin layer of the sorbent in an upward flow of hexane with the subsequent determination of their presence by the sulfuric acid : formalin developer. The determination of additives in the adsorbent samples was carried out by the method of reverse phase high performance liquid chromatography according to the technique that included two-stage extraction of analytes with the hexane and acetone solutions, their re-dissolution in acetonitrile, and the ensuing analysis. The highest content of turbine oil was observed in the upper and middle layers of the modified silica gel. The conditions for the extraction of turbine oil components from the spent adsorbent have been optimized. Various extractants and their volumes for the greatest extraction of turbine oil components from the adsorbent were studied. The stability of turbine oil additives on the modified silica gel was studied during its high-temperature regeneration by modeling the adsorbent regeneration process under the conditions close to production. It is shown that some components of turbine oil were resistant to the regeneration. For example, additives D-157 and V-15/41, the concentrations of which were comparable before and after the regeneration. The proposed analytical scheme for determining the components of turbine oil on the real adsorbent sample was tested. When determining the thermally stable components on the spent modified alumina silica gel, the mass of turbine oil accumulated in the adsorbent over the entire service life was calculated and amounted to 9.5 g per 1 kg of adsorbent. Keywords: natural gas purification, silica gel, regeneration, turbine oil, additives, HPLC DOI: http://dx.doi.org/10.15826/analitika.2020.24.3.002 Yu.A. Ivanova, Z.A. Temerdashev, I.A. Kolychev, A. V. Rudenko Kuban State University (KubSU), ul. Stavropolskaia, 149, Krasnodar, 350040, Russian Federation

The formation of hexagonal microarrays of nanoholes (metasurfaces) in a 50-nm hydrogenated amorphous silicon film by means of three-beam interference of femtosecond laser pulses of the visible range (wavelength 515 nm) is studied experimentally with various exposures of the film. Characterization of arrays by scanning electron and optical microscopy, as well as optical transmission and reflection microspectroscopy, shows that an increase in the number of fixed energy laser pulses leads to a gradual evaporative formation of nanoholes in the film and, overall, the metasurface. Raman microspectroscopy reveals a simultaneous growth of the volume content of the crystal phase.

Chocolate glaze consists mainly of sugar (50%) and fat (35%) and is a high-calorie semi-finished product with a high content of simple carbohydrates. The standard for glaze provides the possibility of producing chocolate glaze with fruit and vegetable components, which reduces the content of simple carbohydrates. Studied and justified the criteria for the production of chocolate glazes with different contents of fruit and vegetable powders. Analysis of the rheological parameters of chocolate semi-finished products showed that the introduction of fruit and vegetable powder instead of part of the sugar leads to a significant change in the nature of the rheological behavior of the semi-finished product. The yield strength increases from 3.4 to 12.6 Pa as the proportion of fruit and vegetable powder in the formulation increases. In order to determine the effect of the production method on changes in the yield strength of fruit and vegetable chocolate glaze, a series of experiments was carried out. It was found that with a constant content of fruit and vegetable powder (11%), temperature, processing time and machine support, the resulting chocolate glazes differed in their rheological characteristics. It was found that the greatest reduction in the yield strength of fruit and vegetable chocolate glazes during the production process can be achieved by stage-by-stage grinding of the formulation components in a ball mill and the additional introduction of PGPR emulsifier at the conching stage. The quality of chocolate semi-finished products depends not only on rheological parameters, but also on crystallization properties. The developed chocolate glazes with different contents of the fruit and vegetable component were processed at a temperature of about 30 °C in a laboratory tempering machine in order to form and stabilize fat crystals in ?-form. Then, the temperindex was determined. It was found that, subject to the same tempering conditions, with an increase in the proportion of fruit and vegetable powder, the temperature of glazes increases. Glazes with a mass fraction of fruit and vegetable powder of more than 7% were distinguished by the properties of re-tempered semi-finished products - the presence of large fat crystals, a rough structure and the absence of surface gloss. In order to obtain the optimal temperature index of glazes with a content of fruit and vegetable raw materials of more than 7%, their tempering modes were developed.