Vol 13, No 9-10 (2018)

Some physicochemical properties of homogeneous and heterogeneous films formed by Au and Cu nanoparticles on graphite are studied by scanning tunneling microscopy and spectroscopy. It is found that the nanoparticles have a shape close to spherical with a diameter of 3‒6 nm, the gold particles do not contain impurities, and the copper particles can be coated with oxide. The adsorption properties of nanostructured coatings with respect to hydrogen, carbon oxide, and oxygen are determined. Copper oxide is reduced by carbon oxide and hydrogen, but the latter is also adsorbed onto oxide-free copper particles and gold. Exposure to oxygen results in the reformation of the oxide on copper. The possibility of rearranging the electronic structure of copper nanoparticles during hydrogen adsorption is confirmed by the results of quantum chemical simulation.

Parameters of structure, dispersity, morphology, and magnetic properties of nanosized powder of magnetite obtained by mechanochemical synthesis from salt systems are reported. Results of using the magnetite nanopowder as a material for skimming mineral oil are discussed.

This is a pioneering work on the low-energy Cu⁺ ion implantation of a с-Ge single crystal at an energy of E = 40 keV using radiation doses of 1.8 × 10¹⁵ to 1.5 × 10¹⁷ ion/cm² and the current density in the ion beam of 5 μA/cm². The surface morphology of samples after implantation has been inspected via scanning electron microscopy and atomic force microscopy. The composition and structure of samples are studied via the microprobe element microanalysis and electron back-scattering diffraction. It is shown that irradiation doses below 1.8 × 10¹⁵ ion/cm² upon the onset of implantation of lead to the amorphization of the с-Ge surface layer. An increase in the threshold implantation dose above 3.1 × 10¹⁵ ion/cm² causes the formation of Cu nanoparticles in the irradiated Ge layer, which are uniformly distributed across the surface. A sample receiving an implantation dose of 6.2 × 10¹⁶ ion/cm² exhibits the formation of a porous mesh Ge structure with Cu nanoparticles at the nodes. The specific resistance measured for samples depends on the implantation dose, increasing for the amorphous implanted Ge layer and doubly decreasing upon the formation of a porous mesh with Cu nanoparticles.

The effect of laser radiation with a wavelength of 970 nm and a power density of 0.29–2.10 W/cm² on the process of atomic layer deposition of alumina films from precursors (trimethylaluminium + water vapor) is studied. Laser irradiation is performed at the stages of reactor purging after the introduction of precursors. The results of a comprehensive analysis involving spectral ellipsometry, atomic force microscopy, X-ray diffractometry, and secondary-ion mass spectrometry have revealed that laser irradiation (i) does not alter the rate of deposition of alumina films onto silicon slices; (ii) does not alter the surface relief (roughness) of alumina films; (iii) does not alter the depth profile of the chemical composition of alumina films; (iv) reduces the average density of irradiated regions of alumina films by 5–10% relative to the density of nonirradiated regions.

Selenium is an essential trace element for humans, animals, and plants, the main function of which is protecting the body from oxidative stress. The use of enriched food products, the seeds of which were treated with a preparation based on nanoscale zero-valent selenium in the form of colloidal solutions, is promising for the physiological requirements of humans. Solutions were prepared by laser ablation and ultrasonic dispersion. Colloidal solutions with selenium concentration up to 9.8 mg/L were obtained. Solutions diluted to a concentration of 0.38 mg/L were used for treating of radish seeds during germination. It was established that nanoscale selenium is less toxic than sodium selenite and selenate and it has significantly accelerated seed germination, leading to an increase in the selenium content and the content of polyphenols in seedlings to a higher extent when compared with hexavalent selenium.

The travel pattern of the nanostructured fibers of aluminium oxyhydroxide in the laminar flow of the argon carrier gas has been developed. On the basis of this pattern, the optimum range of the fiber size, providing the effective transportation of the modifying agent by the gas flows, is determined. Depending on the concentration of fibers, which are transported by the gas flow, the optimum technical parameters of the modifying agent of the aluminium oxyhydroxide for the austenitic steels are determined. The optimum concentration of the nanostructured fibers of aluminium oxyhydroxide in the argon carrier gas is determined. The modeling results and the efficiency of the developed method were verified by experimental researches for the depositing of the surface layers by the argon inert-gas arc welding (MIG welding). It was found that, during the modification of the surface layer, built-up by the nanostructured fibers of the aluminium oxyhydroxide at the amount of 0.2 mg/cm³, the maximum modification effect of this layer of the Fe–C–Cr–Ni–Ti system is expressed. The average size of dendrite shows a decrease of 4.5 times in width due to the formation of the additional centers in the melt being inoculants in the crystallizing metal. The share of the most favorable structure of the nonoriented dendrites in the bulk of the deposited layer increases from 43 to 62%.

Four types of carbon fiber materials (CFMs) obtained by electrospinning polyacrylonitrile solutions are considered. The CFMs intertwine with cells of Gluconobacter oxydans or with their membrane fractions (MFs). Bioelectrochemical characteristics of the electrodes (chrono- and voltamperometric, as well as impedance spectra) are studied. Electrodes are considered a model of the anode of the microbial biofuel cell (MFC). Ethyl alcohol is the oxidized substrate. MALDI-TOF MS demonstrates that MFs retain the protein structure of whole cells and therefore can be used as analogues of whole cells. It is shown that the MFC based on carbon fiber material obtained after 30-min treatment at 1000°C has the highest power and stability. When MFs are used as a biocatalyst, nonmediated charge transfer is observed for all studied CFMs. These results can be successfully used for the design of biosensors and MFCs.

Using the method of cryochemical synthesis, systems of prolonged release of gentamicin sulfate modified with silver (2–30 nm) and copper (1–9 nm) nanoparticles from cryostructured biopolymer matrices based on gelatin with a pore size of 10‒50 μm are obtained. The composition and structure of the systems are confirmed by the data of IR, UV, and NMR spectroscopy; TEM; SEM; and thermoanalytical methods of analysis, and the rate of release of the drug is determined by conductometry. Hybrid composites based on metals and gentamicin sulfate showed greater activity in suppressing the growth of E. coli 52 and S. aureus 144 than their components separately.

Photosensitive layers of metal complexes of anionic polymethine dyes are prepared on ITO-coated glass electrodes using an electrosynthetic route in which a thin metal film (zinc or cadmium) electrodeposited on an ITO electrode is converted electrochemically into a respective dye–metal complex. Optical absorption measurements suggest that the prepared metal complexes of dyes exist onto ITO electrodes in the form of J-aggregates. We investigate the spectral and photoelectric characteristics of these dye–metal complexes. For the dye–metal complexes prepared using the electrosynthetic route, the quantum efficiency of photoconductivity is found to be around 5–7%. Our results show that the technique for the electrosynthesis of photosensitive layers comprised of metal complexes of anionic polymethine dyes on ITO electrodes is promising for the nanotechnology fabrication of thin-film photoelectric converters.