Особенности распространения стоячих электромагнитных и электронных волн в металлическом проводнике с электрическим переменным током проводимости

The paper demonstrates the results of approximate calculations on the establishment of basic features of the propagation of standing transversal electromagnetic waves (EMWs) and standing longitudinal de Broglie electronic waves in a homogeneous not massive non-magnetic metallic conductor of finite dimensions (the radius r0 and the length l0 >>r0) with the alternating axial-flow current of conductivity of i0(t) of different peak-temporal parameters. The correlation for the rated estimation of the average velocity of propagation of the standing transversal EMWs and standing longitudinal de Broglie electronic waves in a metal (alloy) of the indicated conductor is presented. It is shown that quantized standing transversal EMWs arising in a metallic conductor of finite dimensions substantially differ from ordinary transversal EMWs, propagated in the conducting environments of unlimited dimensions. An important feature of the standing transversal EMWs in the examined conductor is the fact that their tension of an axial-flow electric-field advances by a phase their tension of an azimuthal magnetic-field on the corner of π/2. It was established that in the standing transversal EMWs of the used conductor the energy of their electric field only passes into the energy of their magnetic field and vice versa. Therefore the standing transversal EMWs do not transfer the flows of the electromagnetic energy on the surface of the studied conductor.

К вопросу об оптимальной микробиологической деконтаминации воздушной среды и поверхностей

Modern civilization, providing economic and social progress, at the same time objectively creates – sometimes close to ideal – conditions for the spread of various infections. The catastrophic consequences of the SARS-CoV-2 pandemic clearly indicate that homo sapiens appeared to be unable to resist effectively the onslaught of the coronavirus. The purpose of this publication is an attempt to fill the gap in the development of effective methods and means for microbiological decontamination that are optimal in terms of critical parameters. Observational data indicate that a significant number of SARS-CoV-2 coronavirus infections occur by air without a direct contact with the source, including, over a long time interval. Precipitations help to cleanse the air from pollutants and viruses, reducing non-contact contamination, which additionally brings up to date the problem of optimal microbiological decontamination of the air environment and surfaces. A thermodynamic approach has been used to optimize microbiological sterilization. It is shown that irreversible chemical oxidation reactions are the shortest way to achieve sterility, and they are capable of providing high reliability of deconta-mination. It has been established that oxygen is an optimal oxidant, also from the point of view of ecology, since its reactive forms harmoniously fit into natural exchange cycles. The optimal method for obtaining reactive oxygen species for disinfection is the use of low-temperature (“cold”) plasma, which provides energy-efficient generation of oxidative reactive forms – atomic oxygen (O), ozone (O3), hydroxyl radical (·OH), hydrogen peroxide (H2O2), superoxide (O2-), and singlet oxygen O2(a1Δg). Due to a short lifetime for most of the above forms outside the plasma applicator, remote from the plasma generator objects should be sterilized with ozone (O3), the minimum lifetime of which is quite long. It has been substantiated that the microwave method of generating oxygen plasma is optimal for the energy efficient ozone production. A modular principle of generation is proposed for varying the productivity of ozone generating units over a wide range. The module has been developed on the base of an adapted serial microwave oven, in which a non-self-sustaining microwave discharge is maintained thanks to ionizers (igniters), including those based on radiating radionuclides-emitters. In case of massive contamination of surfaces, it is advisable – in addition to ozone (O3) air disinfecting – to use aqueous solutions of hydrogen peroxide (H2O2). It is essential that these reactive oxygen species for disinfecting remote from the plasma generator objects are highly efficient and, at the same time, environmentally neutral. Reliable and affordable personal protective equipment is proposed for activities in zones of increased ozone concentration. The considered optimal means of disinfection can be applicable not only in medicine, but also adapted for numerous practices in agriculture, industry, and in everyday life.

Квантовый размерный эффект и осцилляции Шубникова–де Гааза в поперечном магнитном поле в полупроводниковых нитях Bi0,92Sb0,08

The transport properties, magnetoresistance, and Shubnikov–de Haas (SdH) oscillations of glass-coated Bi0.92Sb0.08 single-crystal wires with diameters of 180 nm to 2.2 mm and the (1011) orientation along the wire axis, which are prepared by liquid phase casting, have been studied. For the first time, it has been found that the energy gap DE increases by a factor of 4 with a decrease in the wire diameter d owing to the manifestation of the quantum size effect. This significant increase in the energy gap can occur under conditions of an energy–momentum linear dispersion relation, which is characteristic of both the gapless state and the surface states of a topological insulator. It has been shown that, in a strong magnetic field at low temperatures, a semiconductor–semimetal transition occurs; it is evident in the temperature dependences of resistance in a magnetic field. An analysis of the SdH oscillations, namely, the phase shift of the Landau levels and the features of the angular dependences of the oscillation periods, suggests that the combination of the manifestation of the topological insulator properties and the quantum size effect leads to the occurrence of new effects in low-dimensional structures, which requires new scientific approaches and applications in microelectronics

Функциональные возможности электромагнитно-акустических преобразований в токовом режиме в металлическом расплаве

The paper deals with a symmetric problem on the base of physically substantiated estimates of the processes of electromagnetic-acoustic transformations (EMAT) of energy during the flow of an electric current through a melt, the key parameters of the open problem of the system "Power source parameters – Parameters of the magnetic field and magnetic pressure of the skin layer – Parameters of acoustic disturbances". It was shown that the key parameter when formulating the EMAT problem in technological applications is the geometry of the container with the object of processing and the material of the form. And when solving the problem, they are the parameter of the skin layer and the time dependence of the discharge current. It was established that a part of energy during the formation of the magnetic pressure in the skin layer from the amount of the energy stored in the capacitor bank of the pulse current generator is on the order of 10-4–10-2. The value of this part depends on the period of the discharge current and is proportional to the T1/2. When acoustic disturbances propagate in a melt, the main share of energy losses is determined by the difference in the acoustic stiffness of the melt and the shape of materials. The frequency spectra of the pressure of sound waves at the parameters selected for the analysis can cover the range of up to hundreds kHz, which is a good reason for the realization of resonance effects and the active formation of dissipative structures. Attention is focused on the fact that EMAT effects are manifested in the melt not only under the influence of an acoustic field, but also under that of an electromagnetic one in the skin layer. They are separated in time, but the acoustic field can occupy the entire volume of the melt and its effect is longer in time.

Закономерности образования карбидов титана и вольфрама из продуктов электровзрывного разрушения проводников

A series of electrical explosions in propane-butane of single and strand-connected Ti and W conductors with various diameters was carried out. Electrophysical characteristics of the explosion revealed that resistive heating of conductors is characterized by two monotonically ascending sections on the voltage – current curves separated by a flat segment (plateau), which corresponds to relatively stable electrical resistivity of refractory metals in the liquid state. The energy deposited by changing the power input into the conductor during its resistive heating, which can be higher or lower than its sublimation energy and can be regulated by changing the external adjustable parameters of the discharge circuit, is a key indicator determining the structural-phase state of destructed and chemically synthesized products after the explosion. The conditions are achieved under which micro- and nano-sized powder products do not contain residual metals and consist of carbide phases completely (TiC with an average microhardness of 29580 MPa as a result of the titanium explosion and a mixture of W2C+WC1-х, in which stabilized high-temperature non-stoichiometric cubic carbide WC1-x dominates, with an average microhardness of 16770 MPa as a result of tungsten explosion).

Высоковольтная деградация электродов, обусловленная электрохимической инжекцией в жидких диэлектриках

The results of experimental studies of the electrode degradation caused by electrochemical reactions under the action of high-voltage fields are presented. Under study were technical hydrocarbon and polymethylsiloxane (PMS) liquids, their solutions with iodine (I2) at chemically active (Cu) and indifferent (Ti) electrodes. It is shown that in hydrocarbons the Cu electrodes interact intensively with I2, and the cathodic degradation is more intense than the anodic one. The Ti electrodes do not degrade, but physical adsorption of I2 occurs on them in hydrocarbons, and a polymer film forms on them in PMS. The kinetics of degradation in time was studied.

Особенности формирования фазового и элементного состава при электроискровом легировании ручным вибратором повышенной частоты

The phase and elemental compositions of electrospark coatings of nickel and titanium deposited on steel, nickel, and titanium, that is, coatings from TiNiMo-20 and WC92-Co8 on steel at high-frequency electrospark alloying are investigated. It is established that the material of the electrode, of the substrate, and the mode of deposition have the main impact on physical and chemical properties of the formed coatings. A positive influence of high-frequency alloying on quality indicators of the processed surfaces is shown. Both the phase and chemical analyses showed availability of the compounds considerably improving corrosion resistance of the processed surfaces. Alloying with WC92-Co8 electrodes at a high frequency makes it possible to obtain an increased content of tungsten carbide in the deposited layer.

Электрохимический синтез композиционных покрытий Ni/TiO2 из низкотемпературного эвтектического растворителя и электрокаталитические свойства осадков

Kinetics of electrodeposition of composite Ni/TiO2 coatings was studied using the electrolyte based on a deep eutectic solvent (DES) containing choline chloride, ethylene glycol, water additive, and nickel chloride. Degussa P 25 nanopowder was used as a dispersed phase in the electrolyte (1–10 g dm3). The developed electrolyte allows depositing composite coatings with the content of titanium dioxide reaching ~ 10 wt.%. The electrolytic deposition of the composite was shown to obey Guglielmi's kinetic model. The main parameters of co-deposition of TiO2 particles into a nickel matrix were determined in the framework of this kinetic model. The co-deposition of titanium dioxide was found to inhibit the reaction of the nickel ions discharge. Electrocatalytic properties of the prepared composite Ni/TiO2 coatings were evaluated with respect to the hydrogen evolution reaction in an aqueous alkaline solution. A noticeable improvement in the electrocatalytic activity was observed when titanium dioxide particles were introduced into an electrodeposited nickel matrix.

Создание равномерных покрытий импульсным лазерным осаждением

The present paper deals with the selection of laser beam processing parameters that guarantee the formation of thin coatings with even thickness by means of the laser beam deposition. Laser deposition was carried out in the atmosphere of Ar and Si and SiC samples were used as a source for the deposited material. Preliminary experiments show that there is a direct dependency between the brightness of the image of the deposited layer (at uniform illumination conditions) and its thickness. Therefore, it was possible to determine the thickness of the deposited layer for various processing parameters and to calculate the laws of motion of the work piece that guarantee the deposition of the layer with a minimal deviation of thickness from the required value. Calculated parameters were successfully used for the deposition of coatings on a substrate of a relatively large area.

Electrochemical Deposition of ZnS Films from Electrolyte Based on Na2SO3

The paper considers the features of electrochemical growth of zinc sulfide from an aqueous electrolyte based on sodium sulfite and zinc sulfate. The conditions for the electrochemical production of ZnS films are determined. It is shown that the value of the potential at which a ZnS layer is formed is limited by the achievement of the critical current due to the diffusion limitations of the electrochemical process of reducing the sulfite ion. It is shown that the resulting films contain an excess of sulfur, which is removed, and the stoichiometric composition is obtained by heat treatment. Aed mechanism of reactions resulting in the formation of zinc sulfide is proposed.