Low-temperature Nonequilibrium Plasma Research Articles

Analysis of Hydrogen Combustion in a Spark Ignition Research Engine with a Barrier Discharge Igniter

Hydrogen fuel is gaining particular attention in internal combustion engines. In addition to zero-carbon emissions, major advantages relate to its combustion characteristics, which allow a significant increase in thermal efficiency under ultra-lean operation and with very low NOx levels. The ignition system is one of the main technology enablers, as it determines the capability to control ultra-lean operations, avoid backfire phenomena, and/or reduce the risks of abnormal combustions. The latter results from hydrogen’s low ignition energy and it is associated with factors like high-temperature residuals, hot spots, and irregular spark plug discharge. The ACIS gen 2-Barrier Discharge Igniter excels in accelerating the initial flame growth speed by the generation of non-equilibrium low-temperature plasma, a strong ignition promoter for the combined action of kinetic and thermal effects. Moreover, its volumetric discharge facilitates combustion initiation on a wide region, in contrast to the localized ignition of traditional spark systems. In this work we present for the first time, to the best of our knowledge, experimental results showing the performance of a hydrogen engine with a low-temperature plasma discharge. Tests were conducted on a single-cylinder research engine, achieving ultra-lean conditions with cycle-to-cycle variability results below 2.5%. The analysis indicates that the H2-BDI combined solution is capable of accelerating the evolution of the flame front compared to traditional spark plugs, leading to a significant reduction in the cycle-to-cycle variability. A meticulous adjustment of the BDI control parameters further enhances igniter performance and contributes to a deeper understanding of the innovative approach proposed in this study.

The use of low-temperature plasma for disinfection of open surfaces of industrial premises

The results of research on inactivation of microorganisms on open surfaces of poultry houses using low-temperature non-equilibrium plasma are presented. AC electrospark discharge at atmospheric pressure was used as its source. Discharge types are streamer, flare. The simultaneous effect of electromagnetic fields, charged particles and chemically active compounds formed by electrospark discharge on the efficiency of pathogenic microflora inactivation for various surfaces (acrylic primer, epoxy resin, yacht varnish, concrete-graphite mixture) is considered. The material to be treated (a biological model of the bedding surface of the floor in the poultry house with the applied protective layer) is installed after the electrospark discharge chamber blown with plasmaforming gas (atmospheric air). The main affecting factors are active chemical compounds: ozone; free radicals (OH, O, O2), ultraviolet radiation in the range of 750–1600 THz, electromagnetic radiation from 50 Hz to 980 MHz, charged particles and vibrationally excited nitrogen and oxygen molecules. Characterizations of electromagnetic radiation flux density at electrospark discharge are obtained. According to the research results, the maximum effect of treatment of exposed surfaces with low-temperature non-equilibrium plasma is achieved when epoxy resin is used as a surface protection material. The number of inactivated microorganisms at exposure of 10-20 s reaches 100%. When inactivating microorganisms on exposed surfaces, it is not economically feasible to take exposure time longer than 20 s. The studies found no significant difference when using streamer or flare discharges to treat outdoor facility surfaces.

PECVD Synthesis and Thermoelectric Properties of Thin Films of Lead Chalcogenides (PbTe)1−x(PbS)x

Lead-based ternary-chalcogenide thin films of the (PbTe)1−x(PbS)x system were obtained using the plasma-enhanced chemical-vapor-deposition (PECVD) technique under conditions of a nonequilibrium low-temperature argon plasma of an RF discharge (40.68 MHz) at a reduced pressure (0.01 Torr). High-purity elements were directly used as starting materials, namely Pb, S and Te. Plasma–chemical synthesis was carried out on the surface of c-sapphire and silicon substrate. The physicochemical properties of the films were studied using various analytical methods. The dependence of the Seebeck coefficient, resistivity and power factor on the structural properties and composition has been studied. The thermoelectric characteristics were found to be dependent on film composition. Upon the selection of optimal sulfur concentration, one can increase the power factor compared to single-phase PbS or PbTe films.

Development of Air Conditioning Systems

This paper presents information on the global production and energy consumption of climate equipment. Information is provided on refrigerants used in air conditioning systems, in particular about R22, which was practically abandoned by many countries in the early 2000s, however, in 2018, about half of air conditioners owned by the population worked on R22. According to a number of estimates, 600 to 800 million units are operated in the world, and about 60% of air conditioners are used refrigerants of the hydrofluorocarbon (HFC) group. Many mixed refrigerants based on the hydrofluoroolefin group are considered potentially possible refrigerants to replace the refrigerants of the HFC group (e.g., R407C, R404A, and R410A). Japan and South Korea suggest using the R32 refrigerant. In India, the production of split systems using the R290 refrigerant has been organized. Various types of air conditioners and their production in the world are presented, working mainly on refrigerants of the HFC group, e.g., R407C, R404A, and R410A. The bactericidal treatment of the air environment using electroconvection and low-temperature nonequilibrium plasma is also described, with the results of processing several cultures and metal surfaces obtained by the authors.

Working Out the Processes of Deposition “MetalMetal“ Multi-Layer Coatings (Cu-Mo, Cu-MoN, Cu-C) and Studying the Tribological Characteristics of Friction Pairs

As part of the program to search for new materials with high characteristics according to Avinit vacuum-plasma technologies, based on the complex use of coating methods (CVD + PVD), stimulated by nonequilibrium low-temperature plasma, the technological parameters of applying tightly bonded high-quality multilayer and nano-layer "metalmetal coatings" were worked out:  metal PVD coatings of Mo, Cu;  multi-layer PVD coatings based on Cu-Mo-N;  multi-layer PVD coatings on the basis of (Cu-C) (with different carbon content). Studies of samples with coatings were performed (micro-grinding, coating hardness, determination of surface geometry after coating). The thickness of multilayer coatings is 1...2 microns. with coating hardness of 250-400 kg/mm2. The developed regimes ensure high adhesion and preservation of the hardness of steel DIN 1.2379 within the specified limits. Distortions of the geometry and roughness of the coated surfaces, compared to the condition before the coating, were not detected. Tribological tests of coated samples were carried out. All tested coatings were completely worn out when rubbing steel DIN 1.2379 at very low loads (max up to 300N, then the load did not increase). All coatings had a high coefficient of friction Kfr ≥ 0.15. The use of such coatings in tribocombinations with steel in the form of independent wear-resistant coatings is impractical. They can be considered as soft layers in the development of new structures of antifriction wear-resistant coatings to increase the performance of friction pairs in the "coating-steel" and "coating-coating" tribosystems.

РЕМОНТНЫЕ СТРОИТЕЛЬНЫЕ РАСТВОРЫ, ПОЛУЧЕННЫЕ ПЛАЗМЕННОЙ МОДИФИКАЦИЕЙ И ВИХРЕВОЙ АКТИВАЦИЕЙ

Introduction: The service life of reinforced-concrete structures can be increased with the use of effective repair compositions obtained by activating the original components. Purpose of the study: We aimed to develop effective repair compounds obtained by activating the original components. Methods: To process the original components, low-temperature non-equilibrium plasma (LTNP) and electromagnetic activation in a vortex layer device were used. In the course of the study, we used polypropylene, steel, glass, and basalt fiber and fiber made of structured ferromagnetic microwire. Electron microscopy and X-ray diffraction analysis were applied. Results: It was established that the combined use of the above methods for the modification of raw components makes it possible to improve the strength of these materials by more than 50%, which is due to the characteristics of structure formation in the developed compositions. For instance, LTNP increases the amount of portlandite and reduces the main phases of cement stone— C3S and β-C2S, and vortex activation contributes to an increase in the total number of crystalline phases. Quartz powder particles processed in an electromagnetic mill are characterized by layered structure, high surface roughness, large developed cracking, as well as inclusions as a result of impact action. All that improves the physical and mechanical properties of the resulting repair compositions by an average of 20%. Repair compositions additionally treated with plasma modification feature new hydrated formations on quartz grains.

Investigation of the characteristics of CU2O particles obtained by a plasma-liquid process

PurposeThis paper aims to develop a simple and efficient plasma technology for the production of copper (I) oxide with the ability to control the morphology and size of Cu2O particles. To achieve this goal, the phase composition of the precipitate formed was estimated, the composition and size of the obtained particles were determined and Pourbaix diagrams were constructed.Design/methodology/approachAn integrated approach combining thermodynamic calculations and experimental research methods is used. The constructed Pourbaix diagram makes it possible to suggest the phase composition of the sediment. The use of cyclic voltammetry made it possible to establish the mechanism of deposit formation on the cathode during the treatment of the solution with contact nonequilibrium low-temperature plasma. The resulting product was examined using X-ray phase analysis and scanning electron microscopy.FindingsThe article presents the results of theoretical and experimental studies on the synthesis of copper (II) oxide. The influence of the parameters of plasma-chemical synthesis on the shape and phase composition of the deposits formed has been studied.Originality/valueA plasma-chemical technology for obtaining copper oxide in the form of single crystals of a regular faceted shape is proposed. The mechanism of formation of copper oxide has been established by cyclic voltammetry. The constructed Pourbaix diagrams show the area of existence of the product.

Study of the effect of treatment with non-equilibrium low-temperature plasma on the hygienic properties of lining leathers for shoe with genuine leather upper

the shoe grade is determined by the quality of the materials that make up the product package. Natural lining leathers for shoe with genuine leather upper should differ primarily by high moisture and vapor exchange properties to ensure an optimal microclimate of the inside of the shoe space. In the paper the application possibility of treatment of lining leathers for shoe with genuine leather upper with non-equilibrium low-temperature plasma to obtain a material with improved hygienic characteristics is justified. Because the operating conditions of lining materials for shoe with genuine leather upper are more determined by the process of contact with the surface of the foot than by environmental effect. Thus, the quality of lining materials for shoe with genuine leather upper is determined primarily by compliance with hygienic requirements, among which vapor and air permeability, hygroscopicity; resistance to sweat. In the study it was revealed that because of the treatment with NLTP HFC discharge of pigskin leathers, there is an increase in the parameter values of hygroscopicity by 34%, moisture-yielding capacity by 36%, vapor permeability by 38%, air permeability by 27%, the capacity to absorb sweat vapor by 33% and the capacity to exude sweat vapor by 42%. Consequently, the treatment with NLTP HFC discharge of pigskin leathers for shoe lining with genuine leather upper makes it possible to improve their quality by sequencing their structure, which in turn acts to increase the efficiency and intensity of moisture interchange processes between the material and the environment of the inside of the shoe space, increases the comfort of the latter and prevents potential adverse effect on human well-being.

(Digital Presentation) Investigation of the Influence of Parameters of Contact Nonequilibrium Plasma on the Structure of Copper Oxides

Recently, the interest of researchers in nanodispersed oxides of monovalent and bivalent copper, ferrum, cobalt, nickel, and chromium has significantly increased. At the same time, interest in their micro- and nanosized particles is due, first of all, to a wide range of possibilities for their practical application. Today it is possible to use Cu2O, CuO in the creation of new catalysts for various industrial processes, as a filler for varnishes and paints, antiseptics. Cu2O is used in the production of galvanic cells, other fields of technology, etc. [1]. At the same time, the characteristics and variants of their practical application largely depend on the method of preparation, which usually determines their structure, dimensions, physical and chemical properties, etc. [2].Among the methods for obtaining micro- and nanoparticles, large groups form the methods of chemical, electrochemical, electropulse, and plasma-chemical synthesis, based on the processes of reduction or oxidation of metal ions in solutions, depending on the conditions.Each of these groups has its advantages and disadvantages, but the use of the plasma-electrochemical method (using the treatment of aqueous media with contact low-temperature non-equilibrium plasma (CNP) of reduced pressure) makes it possible to use the advantages of each of the groups [3-5]. However, in this case, it becomes necessary to establish the relationship between the synthesis parameters and the phase composition and morphology of the resulting particles.At the first stage, Pourbaix diagrams were constructed corresponding to the conditions of synthesis in a plasma reactor, and voltammograms were obtained, which made it possible to evaluate the effect of pH synthesis on the composition of products. The morphology of the particles was also studied depending on the current strength of the process at the same initial concentration of Сu2+ in an aqueous solution. The use of X-ray phase analysis and electron microscopy made it possible to evaluate the composition and dimensional characteristics of dry sediments. Thus, at the process current I=200-250 mA, particles were obtained, consisting of intergrowths of crystals, the size of which did not exceed 30 μm, at I=140-200 mA crystals up to 15 μm were obtained, at I=80-140 mA the average crystal size did not exceed 5 µm.The structure of the particles was also established: the largest particles were represented mainly by intergrowths of smaller crystals. It is obvious that the formation of numerous crystallization centers with the simultaneous intense evolution of hydrogen contributes to the fact that the rate of crystal growth at the cathode decreases. At higher current strength parameters, the growth of individual crystals is observed (mainly in the form of octahedrons and cuboctahedrons, the size of which reaches 10-15 μm. A decrease in the current strength leads to a decrease in the particle size - both individual crystals and their intergrowths, which in this case are predominantly octahedral structures, the largest of which are 1–2 µm, and the smaller ones are 100–200 nm.The results of X-ray diffraction analysis show that under the given conditions for the formation of a deposit, the surface of the formed particles consists mainly of Cu2O.On the basis of the conducted studies, it can be noted that the size of the precipitate particles obtained can vary within a fairly wide range. In this case, a change in the process parameters, especially a decrease in the process current, leads to a decrease in the size of the formed particles and an increase in the deposit uniformity, which is confirmed by the results of electron microscopic studies of the synthesized cathode deposits. This makes it possible to control the particle synthesis process by adjusting the parameters of the plasma-chemical processing process, which, due to its simple design, does not cause difficulties and, along with the possibility of using highly diluted solutions, is an advantage of this method.

Plasma-Chemical Synthesis and Properties of Oxide Compounds of Cobalt

To date, the possibilities of using metal oxide particles in various fields have been developed [1]. At the same time, their characteristics largely depend on the method of preparation, which usually determines their structure, size, and physicochemical properties [2].Among the methods for obtaining nanosized particles, one can single out methods of green synthesis [3], electrochemical [4], electropulse [5], and plasmachemical [6] synthesis based on the reduction or oxidation of metal ions in solutions under favorable conditions, followed by aggregation of nanoparticles.The purpose of this work is to analyze the technology for the synthesis of cobalt oxide compounds using contact nonequilibrium low-temperature plasma and to determine the directions for its further improvement.The object of the study was the process of obtaining particles of cobalt oxide using contact non-equilibrium low-pressure plasma during the processing of a liquid medium.The study was carried out using laboratory equipment and software modules of the HSC Chemistry 5.11 package. To find the preliminary conditions for the formation of interphase boundaries, diagrams were used in the coordinates of the E-pH potential of the aquatic environment (Pourbaix diagrams). It has been established that, depending on the initial state of Co(OH)2 in solution, the mass fraction of oxygen in the precipitate can change. In this case, the addition of hydrogen peroxide leads to a decrease in the proportion of hydroxide compounds in sediments. X-ray phase analysis showed the presence of CoO, CoOOH, Co3O4, β-Co(OH)2, Co in dry sediments. It has been established that the particle sizes lie in the range of 10 – 110 nm. The micrographs confirm the agreement between the calculated values and the experimental data.The phase composition of the deposit is influenced by the following factors: current density and anion concentration, process temperature. Increasing the temperature increases the diffusion coefficient but requires a higher current density to produce a powder. It has been established that a decrease in the liquid layer contributes to an increase in the yield of oxide compounds. The results of the analysis allow us to conclude that when using the technologies of plasma-chemical processing of liquid media to obtain compounds of the ultra- and nanoscale range, it becomes necessary to choose the parameters that are optimal for this process. The results of the analysis allow us to conclude that this technology can be optimized by controlling the initial pH of the solution; use of the spent solution in a container with the initial solution for its acidification; refinement of the reactor block for treating the solution in a film mode or close to it; choice of rational parameters for sludge drying. Laurent S., Boutry S., Muller R. N. Metal oxide particles and their prospects for applications //Iron oxide nanoparticles for biomedical applications. – Elsevier, 2018. –P. 3-42.Wang L. et al. Rational design, synthesis, adsorption principles and applications of metal oxide adsorbents: a review //Nanoscale. – 2020. – Vol. 12. – №. 8. – P. 4790-4815.El Shafey A. M. Green synthesis of metal and metal oxide nanoparticles from plant leaf extracts and their applications: A review //Green Processing and Synthesis. – 2020. – Vol. 9. – №. 1. – P. 304-339.Lawrence M. J., Kolodziej A., Rodriguez P. Controllable synthesis of nanostructured metal oxide and oxyhydroxide materials via electrochemical methods //Current Opinion in Electrochemistry. – 2018. – Vol. 10. – P. 7-15.Gan Z. et al. A laser and electric pulse modulated nonvolatile photoelectric response in nanoscale copper dusted metal‐oxide‐semiconductor structures //Advanced Electronic Materials. – 2018. – Vol. 4. – №. 11. – P. 1800234.Shamanin I. et al. Plasmachemical synthesis and evaluation of the thermal conductivity of metal-oxide compounds for prospective nuclear fuel //Journal of Physics: Conference Series. – IOP Publishing, 2019. – Vol. 1145. – №. 1. – P. 012057.

Investigation of Magnetic and Photocatalytic Properties of CoFe2O4 Doped La3+, Nd3+, I3+

Cobalt ferrites are widely used for permanent magnets, magnetic fluids, microwave devices, high density information storage and environmental technologies. The properties of nanosized magnetic materials strongly depend on the shape, size, and phase composition of the particles. The great interest of researchers in nanosized materials in recent years is associated with the possibility of changing the properties of magnetic materials by controlling the particle size and distribution of cations over sublattices in ferrite [1].Nanoparticles of doped cobalt ferrite showed improved physicochemical characteristics compared to individual components due to the synergistic effect of the mutual presence of cations. Currently, various technologies for producing ferrites are used. However, to obtain a single-phase product, calcination of the precursors at a temperature of 1300-1500 0C is required, which causes agglomeration and sintering of the product. The use of modern methods of electrochemical synthesis is the basis for obtaining ferrites from transition materials with a given set of properties. A characteristic recent trend is the development of new technologies and compositions for the production of precisely nanodispersed ferrites [2].The purpose of this work is to study the possibility of using contact low-temperature nonequilibrium plasma for the synthesis of cobalt ferrites doped with La3+, Nd3+, I3+ cations, to establish a relationship between the cationic composition of ferrites and its phase composition, magnetic and structural characteristics.Ferrites were synthesized in the form of nanoparticles using contact nonequilibrium low temperature plasma in an electrochemical reactor. The crystalline microstructure of the samples was revealed by X-ray diffraction and X-ray phase methods. The magnetic characteristics were determined from hysteresis loops. The EPR spectra were obtained on a Radiopan SE/X-2543 radiospectrometer. To characterize the EPR signals, the intensity and width of the signal, and the resonant frequency were used. The visualization of the dependences of the technological characteristics of La3+-Nd3+-I3+ ferrites on the cationic composition was carried out by the simplex method using the STATISTICA 12 program.It has been established that the nature of the rare-earth metal cation in cobalt ferrite directly determines the magnetic and photocatalytic properties of spinel ferrites. The effect of the mutual influence of the content of cations on the saturation magnetization and coercive force is determined. The most influencing factor is the content of neodymium cations. Low values of the coercive force for Mn-Zn and Co-Zn ferrites and high values for the entire range of Co-Mn ferrites are established. An increase in the content of cobalt cations leads to an increase in the saturation magnetization value of Co-Mn ferrites. The EPR spectra show that the values of the resonance field and linewidth in the EPR spectrum correlate with the value of magnetic saturation.Simultaneous substitution of Nd3+ and La3+ in CoFe2O4 nanoparticles affected the structure, magnetic and photocatalytic properties. Structural parameters were investigated and calculated using X-ray diffraction studies. The magnetization analyzes were carried out at room temperature. Various magnetic parameters have been obtained and discussed, including remanence (Mr), coercive force (Hc), saturation magnetization (Ms), squareness ratio (SQR=Mr/Ms) and magnetic moment (nB). An increase in Mr, Ms, Hc and nB was found at lower concentrations of Nd3+ and La3+. An increase in the content of Nd3+ cations leads to a significant increase in the coercive force. The analysis of photocatalytic activity in the reaction of isolation of furacilin showed the best results (destruction rate 98%, time 40 minutes) for the ternary composition.References Caldeira, Luis Eduardo, et al. "Correlation of synthesis parameters to the structural and magnetic properties of spinel cobalt ferrites (CoFe2O4)–an experimental and statistical study." Journal of Magnetism and Magnetic Materials550 (2022): 169128.Lu, Yuzheng, et al. "Effect of Gd and Co contents on the microstructural, magneto-optical and electrical characteristics of cobalt ferrite (CoFe2O4) nanoparticles." Ceramics International2 (2022): 2782-2792.

Hydrophilization of the surface of a natural hydrophobic material by non-equilibrium low-temperature plazma

We considered the effect of non-equilibrium low-temperature plasma for hydrophilization the surface of fish skins. Fish skin is a hydrophobic material in its nature. The relevance of this issue is justified by fact that the dressing of animal skin is a series of consecutive liquid processes. Natural structure of fish skins promotes the poor diffusion of working solutions, so it hinders a chemical modification of materials. The plasma processing of fish skin provides the partition of supramolecular structure of collagen (basic protein of dermis) due to disruption of weak intermolecular bonds. This leads to better diffusion of chemical materials and as a result, liquid processes intensify and time production cycle reduces.

TECHNOLOGY FOR OBTAINING SPECIAL LEATHERS WITH IMPROVED PERFORMANCE CHARACTERISTICS, RESISTANT TO OIL AND PETROLEUM PRODUCTS

A technology is proposed for obtaining leathers for the uppers of special footwear intended for employees of oil-producing enterprises. Leathers for uppers made from cattle skins produced by this technology are distinguished by a combination of high strength, hygienic and protective characteristics, including resistance to oil and oil products, as well as to biodegradation. The technology for obtaining special shoe leathers includes a through complex processing of semi-finished leather products with non-equilibrium low-temperature plasma and a solution of silver nanoparticles .

Energetic characteristics of hydrogenated amorphous silicon nanoparticles

• Plasma-synthesized amorphous Si NPs ( a -nSi) incorporate abundant hydrogen. • The reactivity of a -nSi/KClO 4 increases by a factor of six compared with nAl. • The energetic performance of nSi is correlated with its hydrogen content. • In situ release of hydrogen from hydrides enhances the reactivity. In this work, we utilize a low-temperature non-equilibrium plasma to nucleate and grow sub-10 nm Si particles with varying degrees of crystallinity by tuning the level of power coupled into plasma discharge. Temperature-programmed desorption spectroscopy shows that as-prepared amorphous Si nanoparticles ( a -nSi) incorporate more hydrogen than crystalline Si nanoparticles ( c -nSi). Further, hydrogen is incorporated in the material in the form of higher silicon hydrides with a lower desorption temperature. Combustion cell measurements show that when formulated with KClO 4 , a -nSi outperforms its crystalline counterpart with respect to pressure output. The pressurization rate of a -nSi/KClO 4 composite increases by a factor of six compared with nAl to 0.66 MPa·μs −1 . Evidence of hydrogen release (∼730 K) from Temperature-jump time-of-flight mass spectrometry (T-Jump TOFMS) of a -nSi/KClO 4 suggests the creation of Si dangling bonds prior to ignition (∼820 K), which then react exothermically with oxygen liberated from KClO 4 , leading to ignition. Explosive reaction of H 2 /O 2 mixture likely contributes to the rapid pressure rise. The enhanced energetic performance of hydrogenated a -nSi compared to its crystalline counterpart suggests that incorporation of hydrogen is a promising strategy for improving the performance of nanoenergetic materials.

Structure- and excitation-dependent photoluminescence of As–S:Yb3+ films

In the article, we present and discuss the features of the structure and photoluminescence properties of Yb-doped As–S films synthesized by PECVD employing solid-state initial precursors. The doping was carried out during the deposition process. By controlling the temperature of the precursor sources and the composition of the low-temperature nonequilibrium plasma, we synthesized amorphous As–S:Yb films with Yb content ranging from 0.6 to 8.4 at. %. The change in the ratio of structural elements and surface morphology as a function of the elemental composition is shown. The increase of the Yb content leads to a redshift of the short-wavelength absorption edge. The dependence of the shape and intensity of 2F5/2 → 2F7/2 photoluminescence, observed in the range 930–1030 nm on the excitation wavelength (632.8 nm and 785 nm) and Yb concentration was evaluated. The relation between composition and atomic structure of the amorphous matrix of arsenic sulfide on the photoluminescent properties of Yb3+ ions is discussed.

Влияние жесткой и пластичной матриц на предельную прочность и механизмы разрушения полимерных композиционных материалов при ударе и в статике

An universal method “Break upon Impact and Static” (RUS) has been developed for the experimental determination of the ultimate strength properties of polymer composite materials based on multifilament nanocrystalline ultra-high molecular weight polyethylene (UHMWPE) fibers, which differs in the method of fixing the sample in a testing machine.The method is carried out using a uniform BIS-sample with an intermediate matrix at the ends and equipment for its attachment to the platforms of testing machines. The sample is a round composite rod composed of the fibers and matrices under investigation, which is held in the tooling by an additional matrix that fixtures it under various loading rates. The RUS method was used to study the properties and mechanisms of destruction upon impact and in a static situation of anisotropic polymer and hybrid composite materials (PCM and HCM) based on flexible and rigid matrices reinforced with hybrid fibers of carbon, aramid, and UHMWPE-fibers activated by non-equilibrium low-temperature plasma. The breaking loads under low-velocity impact and static bending conditions, relative deformation, specific absorbed-in-fracture energy, work of adhesion, shear strength, and other properties are determined. It was found out that the plasticity of the matrix and the hybrid fiber composition affect the properties and fracture mode of PCM and HCM. For the destruction of HCM with a flexible matrix upon impact, a load twice as large as for composites with a rigid matrix is required. HCMs have the highest strength, in which at all stages of loading up to failure, joint deformation of the matrix and the reinforcing fiber occurs. The mechanism of deformation and destruction of anisotropic HCM upon impact is stepwise, while the nature of the deformation curve is zigzag. In statics, the deformation proceeds smoothly. By changing the ratio of carbon and UHMWPE-fibers during hybridization, it is possible to control the properties of HCM and improve its specific properties. The combination of carbon and UHMWPE-fibers in a hybrid fiber for reinforcing a flexible matrix makes it possible to create a material with a delayed fracture. It has been established that for HCM based on a flexible matrix reinforced with a hybrid fiber combining 20 % carbon and 80 % UHMWPE fiber, the fracture load increases by factor 2, the specific fracture work by 42 %, relative deformation by 68 %.

Food safety of plasma-chemically activated water and bread made with its use

Water treatment by contact non-equilibrium low-temperature plasma refers to innovative methods of processing food raw materials, which requires determining the level of safety of its use to meet the requirements of food safety for humans. The test animals were divided into four test groups with two different basic diets. The tested substances were drinking main water (control group) and plasma-chemically activated water (experimental group); wheat bread (control group) and wheat bread produced using plasma-chemically activated water (experimental group). It was found that there was no significant difference between the control and experimental groups of animals in body weight and its changes during 90 days of the introduction of the test substances into the diet. The amount of water and feed consumed was in direct proportion to the change in the weight of animals in the corresponding diets. The hematological and biochemical analysis of the blood of the test rats did not confirm the toxic or allergenic effect of the studied feeding factors on their organism. An increase in the number of erythrocytes in the blood and activation of the phagocytic activity of experimental groups of animals were confirmed. This confirms the positive effect of plasma-chemically activated water and wheat bread made with its use on metabolic processes in the body of animals. Macromorphological parameters of the body of animals and the results of histological studies of the stomach, liver, kidneys and femur as potential target organs demonstrated the absence of dystrophic-degenerative changes in these organs. A comprehensive study of the food safety of plasma-chemically activated water and wheat bread made with its use proves the possibility of using an innovative method of water treatment in food production.

Synthesis of silver nanoparticles in a plasma electrochemical system for degradation of environmental pollutants

We demonstrate operation of an aqueous electrochemical cell with an atmospheric-pressure contact non-equilibrium low-temperature plasma (CNP) anode and a solid metal cathode for the rapid production of colloidal metal nanoparticles. CNP was utilized to synthesize Ag nanoparticles (AgNPs). The synthesized AgNPs were characterized by using UV–vis spectroscopy, dynamic light scattering, transmission electron microscope. The effect of concentration of Ag+ and type of stabilizing agent on the production of silver nanoparticles has been studied. To optimize the synthesis process the main characteristics of the discharge plasma were studied using UV-spectroscopy by varying the discharge current and solution composition. The AgNPs solution showed catalytic activity for the complete degradation of 4-nitrophenol (4-NPh).

Influence of Nonequilibrium Low-Temperature Plasma on the Properties of Nonwoven Fabric Based on Polypropylene

Investigation of the effect of low-pressure NLTP in nitrogen, argon, propane-butane and air on the properties of a multilayer medical-purpose material based on polypropylene used for the manufacture of sanitary-hygienic and medical products. It is shown that after plasma treatment of argon, nitrogen, propane-butane, the surface polarity of the CMC material changes significantly, as evidenced by a decrease in the wettability angle and an increase in capillarity. The most significant changes in indicators are observed in the case of plasma treatment in argon and nitrogen. However, in the case of argon, less processing time is required to achieve the effect. Plasma treatment leads to a slight decrease in tensile strength, no more than 10-15%. It is also shown that when plasma is treated in an argon atmosphere, such characteristics of a nonwoven material as air permeability, hygroscopicity increase, and a decrease in rigidity is observed. The study of the structure of the material (pore size) showed that the treatment with NLTP leads to a significant decrease in the size of large pores and an increase in the size of medium and small pores

DETERMINATION OF THE OPTIMAL OZONATION MODE FOR WINTER GARLIC PLANTING MATERIAL

The study was carried out at the Institute of Vegetable and Melon Farming of the National Academy of Agrarian Sciences of Ukraine and the Department of Low-Temperature Non-equilibrium Plasma Chemistry of the NSC "Kharkov Institute of Physics and Technology" of the National Academy of Sciences of Ukraine using the varieties of winter garlic, such as Duchess and Merefyanskiy white. Pre-plant treatment with four-time repeatability was carried out 3-5 days before planting using an OzW Stream Ozone TM ozone generator. Laboratory studies of fungal diseases Fusarium and Penicillium progress on the treated material were carried out with four-time repeatability in wet chambers. The effect of ozone concentration of 10, 50, and 100 PPM and exposure time of 10, 60, and 180 min on infestation of garlic with black and green mold was studied.