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The article presents the experimental results on the antibacterial properties of nanobiocomposite (NBC) material, which contains ultradispersed silver nanoparticles (NPs) synthesized with the probiotic Lactobacillus plantarum. Synthesized NBC samples are investigated with transmission and scanning electron microscopies, spectroscopy analysis and electrophoresis method. As shown, the physical and chemical properties of the NBC surface, which are determined by the silver-NPs’ concentration and the pH of the medium, play a significant role in the NBC antimicrobial activity. The electrosurface properties of the nanobiocomposite based on L. plantarum and stabilized in the matrix cell ultradispersed silver are characterized by a low surface charge and a hydrophilic surface. The electrokinetic potential correlates with the content of silver NPs. The AgNPs’ concentration of 15–25 mg/g is optimal and corresponds to the least damage of the cell matrix and the formation of silver NPs in a narrow size range of 2–6 nm. The maximum values of the NBC -potential are in the range of pH 6.5–7.0. Such parameters ensure a high antibacterial effect of NBC. The method of determining the respiratory activity (RA) of the test strain of bacteria E. coli K–A shows the concentration-dependent sensitivity of RA to NBC. The inhibiting concentration of RA by nanobiocomposite is of 6–8 µg/ml. The antibacterial activity of NBC against 17 strains of the pathogenic and opportunistic microorganisms, which are threatening agents of nosocomial diseases and complications in surgical practice, is studied. Almost all tested strains show a wide level of sensitivity to NBC, inhibiting the growth of the gram-(+) and gram-(-) bacteria. The increased activity of NBC in relation to the clinical isolate of S. aureus compared to the museum strain is shown. The minimum inhibitory concentrations (MIC) of NBC for the studied test cultures of microorganisms ranged from 1.5 µg/ml to 3.5 µg/ml. The minimum bactericidal concentration (MBC) of NBC is in the range of 8–22 µg/ml. The results obtained indicate the prospects of the ‘green-synthesized’ product for medicine and veterinary medicine due to the combination of an environmentally safe synthesis method, prolonged mild action and low toxicity, as well as a wide spectrum of antimicrobial activity of NBC. [ABSTRACT FROM AUTHOR]

The goal of the research work was the pyrolytic synthesis of straight and spiral carbon nanotubes of approximately the same diameter, as well as their comprehensive analysis. To solve the given problem, a new installation for the pyrolytic synthesis of carbon nanostructures (CNS) with a fusion reactor, which for each fusion process can have its own angle relative to the classical horizontal position of the reactor axis. This reactor made it possible to develop a method for obtaining conglomerates of spiral-shaped multi-walled carbon nanotubes with a diameter of 15–60 nm and to synthesize straight multi-walled carbon nanotubes with a diameter of 5 to 60 nm. The research of pyrolytic synthesis of carbon nanostructures in a vertical reactor allows to work out the technology of purposeful synthesis of nanotubes that have a spiral shape with a certain diameter and pitch of the turn. As part of the work, a new mechanism for the formation of spiral multi-walled carbon nanotubes is also considered and proposed, which is important for their further industrial synthesis and their use in related composites. A scheme is proposed of conditions for the synthesis of carbon nanostructures by the pyrolytic method. Thermal analysis was carried out in the work, which recorded the presence of two different structures with low thermal stability (probably amorphous carbon and higher hydrocarbons). When using scanning and transmission electron microscopy, the formation of spiral nanofibers with a diameter of 15–60 nm in the vertical position of the reactor was recorded, and in the horizontal position of the reactor, the formation of straight and slightly curved MWCTs with a diameter of nanofibers from 5 to 60 nm was found. Raman spectroscopy confirms the presence of multi-layered carbon tubular formation, i.e. MWCT, in both synthesis products. [ABSTRACT FROM AUTHOR]

Carbon nanostructures (CNS) of different types (carbon nanotubes, fullerenes and fullerene-like structures) are obtained by the method of electricarc evaporation of graphite grades, namely, SIGE (special impregnated graphite electrodes) and FGDG-7 (fine grained dense graphite with a density of 7), within the inert gas (He). A comparative analysis of synthesizedCNS characteristics is performed. The optimal technological conditions for the synthesis of CNS from graphite anode electrodes of comparable grades (SIGE and FGDG-7) are determined. Deposits of plasma chemical synthesis are studied. The structure of the synthesized carbon materials is studied by scanning and transmission electron microscopies, and as shown, carbon nanotubes are formed during the evaporation of SIGE brand graphite even without the use of a catalyst. Differential-thermal, thermogravimetric and differential thermogravimetric analyses are performed, according to the results of which the temperatures of the beginning of interaction of the formed CNS with air oxygen are established. According to the data of the photospectral analysis of the synthesis products, calculations are performed, and it is shown that the fullerene component obtained by evaporation of SIGE brand graphite contains 10–12% of the C60 and C70 fullerenes that is not inferior to similar indicators of FGDG-7 brand graphite. Taking into account the cheapness of SIGE brand graphite compared to FGDG-7 graphite brand, it can be argued that carbon nanostructures synthesized from SIGE brand graphite have a lower cost. This fact is important for the synthesis of carbon nanostructures as filler for state-of-the-art composites. In addition, the synthesis of much cheaper fullerene and fullerene-like molecules is a great advantage for their study and using in state-of-the-art materials, because today, new state-of-the-art nanotechnologies on the base of fullerenes are beginning to be created. [ABSTRACT FROM AUTHOR]

Post-traumatic muscle ischemia results from severe injury and can lead to muscle dysfunction. Therefore, patient management and treatment are very significant in all periods of injury. New methods are performed, especially using regenerative technologies to avoid complications and improve longterm outcomes. Objective. To determine histological changes in the muscles of the injured limb after traumatic ischemia after injection of plateletrich plasma, Bone marrow stem cell concentrate (BMAC), and Stromal vascular fraction (SVF) prepared from adipose tissue on the 5, 15, and 30 days. Material and methods. Experiments were conducted on rabbits (Chinchilla breed). A tourniquet imposed on a lower limb, from the middle third of the thigh to the ankle joint. After 6 hours, the tourniquet was removed. The animals were divided into four groups: control, plateletrich plasma, bone marrow stem cell concentrate, and stromal vascular fraction prepared from adipose tissue--histological muscle changes provided by Tescan Mira 3 LMU (Czech Republic) in scanning transmission electron microscopy. Results. On the 5th day after the experiment were no significant histological changes in muscles but in the contrary on the 15 days after experiment in BMAC and SVF groups detected new muscle fibers formation in necrotic areas and myonucleus organization. On the 30th day new angiogenesis was detected around muscle fibers. Plateletrich plasma group characterized by massive connective tissue formation in necrotic areas. Conclusions. Necrosis and progressive muscle hypotrophy are unavoidably for this type of injury. It was shown that BMAC and SVF could stimulate regeneration and angiogenesis. [ABSTRACT FROM AUTHOR]

The results of experimental studies of the structure and phase composition of the base metal and metal of the heat affected zone (HAZ) of model samples of high-strength low-carbon steel Alform 620M in conditions of various cooling rates (W6/5) are presented, using a set of research methods including light, scanning and transmission electron microscopies. The goal is to study the influence of the structural and phase composition of the heat affected zone metal on its physical and mechanical properties, depending on the technological parameters of arc welding (W6/5 = 3°C/s, 12°C/s and 25°C/s) at all structural levels (from grain to dislocation), as well as conditions for further operation (external static and dynamic load). Structural-phase characteristics are investigated--grain and sub-grain structure size, phase separation distribution, features of brittle and ductile fracture zones, distribution patterns of dislocation density in HAZ metal models. Comprehensive studies have made it possible to evaluate the differential contribution of certain structuralphase components that are formed under various welding modes, in optimizing the most important for operating conditions of mechanical characteristics of welded joints. Studies have shown that the base metal of high-strength Alform 620M steel has a fine-grained bainite structure with homogeneously distributed dislocation density and a lack of fragile destruction, which provides a high level of mechanical properties (strength, plasticity) and crack resistance of the metal. In model steel samples, when the cooling rate increases from W6/5 = 3°C/s to W6/5 = 25°C/s, the structural composition of the metal changes with an increase in the amount of lower bainite and dispersion of the structural components with homogeneous distribution of dislocation density. The optimum mode of cooling (W6/5 = 25°C/s) is revealed, which, in point of view of the structure and phase composition, provides the highest level of mechanical properties and crack resistance of the Alform 620M highstrength steel welded joints. [ABSTRACT FROM AUTHOR]

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