Regularities of structure formation of bimetallic elements of aluminum-manganese bronze CuAl9Mn2 and low-alloy structural steel A516 using different sequences of component deposition during printing by wire-arc additive manufacturing are investigated. It is found out that the sequence of material deposition affects the product structure and mechanical properties. Due to the differing melting points of bronze and steel, the samples show either a sharp fusion boundary between the components or their highly diluted mixture. According to the mechanical tests, the ultimate strength of the steel/bronze specimens reaches 450 MPa, while that of the bronze/steel specimens has lower values (220–350 MPa) due to the presence of defects.

The impact of heat input and scanning strategy during the printing of CuAl9Mn2 bronze by wire-arc additive technology on the structure, geometric parameters, and properties of the resulting products is examined. It is demonstrated that a higher rate of layer deposition results in enhanced mechanical properties of the material and smaller wall width and layer height. This enables the geometric parameters of the formed samples to be adjusted during printing. The deposition strategy also has a significant impact on the geometry of the products with round or rectangular cross-sections.

Electron beam additive wire feed manufacturing has been applied for depositing AlSi12 layers on the AA5056 substrate to form a wall. The accelerating voltage and horizontal deposition speed were kept constant at 30 kV and 375 mm/min, respectively, while the heat input was changed by exponentially changing the beam current from 25 mA when depositing the first layers on a substrate to 18 mA when depositing the last top layers. Three structurally different zones have been obtained depending upon the multilayer sample. Microstructure, microhardness, corrosion resistance, phase and elemental composition of these zones have been investigated. The layer-by-layer deposition strategy resulted in admixing Mg from the melted AA5056 into transition zone as well as into as-deposited AlSi12 layers. The resulting as-deposited AlSi12 alloy structure was represented by & alpha;-Al dendrites and & alpha;-Al + Si eutectics with fine Mg2Si particles. The transition zone contained & alpha;-Al grains with coarse & alpha;-Al + Mg2Si eutectics, which had an adverse effect on its corrosion resistance but allowed improving the tensile strength as compared to that of as-deposited AlSi12 whose tensile strength at the level of 207 MPa was determined by microstructure of the deposited AlSi12 layers containing & alpha;-Al dendrites, & alpha;-Al + Si eutectics and fine Mg2Si precipitates. The as-deposited AlSi12 showed the maximum corrosion resistance with corrosion potential at -545 mV.

Using a simultaneous electrical explosion of two twisted wires, bimetallic Ti–Ag and Fe–Ag nanoparticles are synthesized, where the component ratios are 76–24 and 75–25, respectively. The resulting nanoparticles are characterized by the methods of X-ray diffraction analysis, transmission electron microscopy, thermal desorption of nitrogen, and microelectrophoresis. It is found out that the synthesized nanoparticles are mainly structured as Janus-nanoparticles, and in nanopowders they form weakly-bonded aggregates and hard agglomerates, where the particles are connected by silver ‘necks’. The negative charge of the particles and their ability towards degassing under ultrasonic action make it possible for the Ti–Ag and Fe–Ag to be used as effective antimicrobial modifiers of water-soluble polymers forming stable gel-like compositions. These compositions possess significant antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) bacteria, which exceeds that of similar compositions containing silver nanoparticles only.

The present study deals with porous hematite nanostructures as antimicrobial drug delivery systems. Obtained nanoparticles have been analyzed by Transmission Electron Microscopy (TEM) and X-Ray Diffraction analysis. Porous ellipsoidal particles with a size range of 50–200 nm, which consist of 2–10 nm fragments, were observed. Drug adsorption onto the hematite nanostructures surface has been examined using penicillin and vancomycin as a model systems. Obtained adsorption isotherms represent weak interaction between adsorbate and adsorbent. The maximum adsorption capacities of penicillin and vancomycin were 8 and 6 mg/g respectively. The results suggest that synthesized hematite nanostructures could be used as drug carriers into Fe-Fe2O3 implants.

In the present work poly(sodium acrylate)-capped mesoporous boehmite nanostructures (AlOOH/PNaA) were synthesized by hydrothermal oxidation of aluminum nanoparticles in sodium polyacrylate aqueous solution. The influence of the polymer concentration on the products morphology and their surface area has been demonstrated. Optimal conditions to the one-step synthesis of polymer-grafted mesoporous boehmite nanostructures were determined. Synthesized nanostructures with a size of less than 200 nm have a specific surface area of 169.2 m(2)g(-1). Moreover, the amount of grafted polymer of the modified nanoparticles was about 2.5 wt %. The zeta potential of the synthesized nanoparticles AlOOH/PNaA depends on the pH medium value. Thus, material adsorption properties differ in acidic and alkaline media. The results will be used further for the development of boehmite-based drug carrier systems for controlled drug delivery.

In present work the AlOOH-Fe2O3 modified cellulose acetate fibres were prepared by a two-step method. Firstly, the cellulose acetate fibres were treated in aluminum nanoparticles aqueous suspension followed by their water oxidation. The nanoparticles react with water with the flower-shape boehmite AlOOH nanostructures formation. Secondly, AlOOH-modified fibres were treated with Fe2O3 nanoparticles water suspension. Fe2O3 nanoparticles were previously obtained by hydrolysis of iron acetate. The color of the modified fibres changed from white to brown. The physical and chemical properties of the nanoparticles and fibres were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, adsorption of nitrogen and electrophoretic mobility. The antibacterial activity of fibres against E. coli, P. aeruginosa, S. aureus and MRSA was studied. Reduction of the concentration of viable bacteria reached 100% after exposure of the bacteria to AlOOH-Fe2O3 modified fibres for 1 h. The viability of L 929 mouse fibroblast cell line in presence of fibres was investigated.

In the present study, the process of aluminum nitride composition in poly(sodium acrylate) aqueous solution was studied. The final products of the reaction are boehmite (gamma-AlOOH) porous nanoparticles with overall particle size 50-200 nm covered with crumpled nanosheets with 2-5 nm width and up to 50 nm overall size. Carrying the oxidation process in poly(sodium acrylate) aqueous solution allows to change the mechanism of boehmite nanosheets formation in contrast to water. That can be ascribed to the chelating ability of the polymer carboxyl groups towards Al3+ ions and changes in hydrolysis rate of aluminum aqua complexes. Synthesized gamma-AlOOH nanostructures possess a high BET specific surface area and contain micro- and mesopores. The present results of the study can be used for further development of new sorbents, drug -delivery systems and different antimicrobial materials.

In the present study, novel nanoparticle-hydrogel composites have been synthesized as a potential hemostatic wound-healing agent. Poly(sodium acrylate) has been cross-linked by aluminum ions, forming physical hydrogel, which was used as a matrix, while nanoscale boehmite (gamma-AlOOH) and Fe2O3 were used as fillers. A new approach to hydrogel synthesis has been proposed. This technique involves oxidation of aluminum nanoparticles suspended in poly(sodium acrylate) concentrated solution, thus, generating aluminum ions, which serve as a cross-linking agent, forming hydrogel network. In order to obtain nanoparticle-hydrogel composites, nanoscale fillers were added to polymer solution prior to hydrogel formation. MTT-assay, performed for analyzing the cytotoxic effects of all synthesized nanocomposites, revealed its non-toxicity at the concentrations 0.1-0.00625 mg/ml.

ЭЛЕКТРИЧЕСКИЙ ВЗРЫВ ПРОВОДНИКОВ ДЛЯ ПОЛУЧЕНИЯ БИМЕТАЛЛИЧЕСКИХАНТИБАКТЕРИАЛЬНЫХ НАНОЧАСТИЦ Ti-Ag И Fe-Ag * * Синтез и исследование наночастиц Ti-Ag выполнены в

Separation of glyoxylic acid from unpurified multicomponent technological mixtures, resulting in the process of direct oxidation of glyoxal, and preparation of sodium glyoxylate are developed. The mixtures are treated with an optimal amount of CaCO3, which has to be prespecified by acidic-basic titration of the technological mixtures. Both separation of glyoxylic acid and preparation of sodium glyoxylate take place owing to ionic exchange reactions: calcium glyoxylate is easily converted into glyoxylic acid by action of oxalic acid. Reaction with Na2CO3 leads to the formation of sodium glyoxylate.

Synthesis of glyoxylic acid was carried out by oxidation of glyoxal aqueous solutions by nitric acid. Glyoxylic acid and oxalic acid (as a by-product) were isolated from technological mixtures in the form of their calcium salts in a strictly defined region of pH. Previously, model calcium salts were synthesized from the commercial acids as reference objects.The results of infrared spectroscopy and complexometric titration of precipitates of calcium salts of glyoxylic and oxalic acids, isolated in various pH regions, allow one to construct reliable research strategies of complex mixtures, such as obtained from the oxidation products of aqueous solutions of glyoxal.

Electron beam processing is one of the effective methods for modification of surface material properties. Influence of electron beam irradiation on the structure of polymeric materials such as polyvinyl alcohol and polylactic acid was investigated. Electron beam processing was carried out at 8 kV accelerating voltage and a pressure of 3 x 10-2 Torr, the emission current was from 25 to 40 A, the pulse duration was from 150 to 300 μs and the pulse number was from 1 to 10. The elemental composition and the structural state of the surface of irradiated polymer materials were studied by infrared spectroscopy (IR-spectroscopy), X-ray photoelectron spectroscopy (XPS), scanning-electron microscopy (SEM) and atomic-force microscopy (AFM) methods. It was established that certain chemical processes take place and some physicochemical properties change under electron treatment.