Abstract: 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. PubDate: 2018-09-01
Abstract: — 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. PubDate: 2018-09-01
Abstract: 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%. PubDate: 2018-09-01
Abstract: — 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. PubDate: 2018-09-01
Abstract: 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. PubDate: 2018-09-01
Abstract: 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. PubDate: 2018-09-01
Abstract: 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. PubDate: 2018-09-01
Abstract: The specific energy parameters of nanostructured electrode materials of electrochemical capacitors obtained by the method of multistage calendering are studied in this work. The dependence of electrical conductivity; the specific capacity of an electrical double layer of electrodes; and the internal resistance of electrochemical capacitors on the nature, quantity, and spatial localization (in the volume of the active layer and/or at the active layer–current collector interface) of conductive dopants (carbon black and grown in vacuum carbon fibers) are examined. PubDate: 2018-09-01
Abstract: 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. PubDate: 2018-09-01
Abstract: The influence of titanium doping of diamond-like nanocomposite films a-C:H,Si:O on the process of their structuring by the technique of bias-induced probe nanolithography of the scanning probe microscope (SPM) was studied. It has been found that titanium doping suppresses formation of dendritic-like structures that grow in undoped a-C:H,Si:O films at relative humidity above 50%. Instead of dendritic-like nanostructures, hill-like protrusions arise. At the same time, a decrease in the electrical conductivity and an increase in the friction forces in the modified region are close to those on films without metal. The mechanisms of the observed effects are discussed. PubDate: 2018-09-01
Abstract: The nanostructured modification of an MB-2 bipolar membrane with chromium(III) hydroxide is performed. Using the methods of scanning electron microscopy, energy dispersive analysis, X-ray diffractometry, and impedance spectroscopy, the morphology and phase and chemical composition, as well as the electrochemical properties of the modified membrane, are studied. Its electrochemical behavior in the process of conversion of ammonium nitrate was studied: the yield of the acid and base, the energy consumption of the process, and the degree of contamination of the target products with salt ions are evaluated. It is shown that the bulk modification of the cation-exchange layer of the MB-2 membrane with nanosized Cr(OH)3 allows one to achieve the electrochemical characteristics of a bipolar membrane comparable to those of Fumasep FBM and MB-3 membranes. PubDate: 2018-09-01
Abstract: The ability of the suspension culture of Arabidopsis thaliana cells and Dunaliella salina microalga to reduce gold ions with the formation of nanoparticles is shown. The average diameter of gold nanoparticles obtained using D. salina for synthesis appeared to be less than when using A. thaliana cells: 8 and 25 nm, respectively. Freshly prepared culture media used for growing cells of both dunaliella and arabidopsis did not reduce gold salts with the formation of nanoparticles. After the cells were grown and freed by centrifugation and/or filtration, culture media turned out to be capable of gold reduction. PubDate: 2018-09-01
Abstract: The creation of three-dimensional structures possessing biomimetic properties is of considerable interest for regenerative medicine. Nonwoven materials with a diameter of fibers from 100 nm to 3 µm have been obtained by electrospinning from dispersions of collagen in hexafluoroisopropanol and acetic acid (AA). A study by the circular dichroism method indicates the predominant preservation of a collagen triple helix in produced materials. To preserve the fibrous structure in aqueous media, collagen is cross-linked by genipin in isopropanol and PBS (phosphate buffered saline, pH 7.4). The mechanical and biological properties of cross-linked materials have been studied—it is shown that the mechanical behavior of collagen materials in the physiological range of loads corresponds to the mechanical behavior of the native aorta. Cross-linked fibrous materials do not possess cytotoxicity, and they contribute to the adhesion and proliferation of cells. PubDate: 2018-09-01
Abstract: — 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. PubDate: 2018-09-01
Abstract: Abstract The effect of detonation-synthesis nanodiamonds (NDs) on the viability of bacterium Rhodococcus sp. 2012B and its capability for ND biodegradation was determined. It was shown that NDs did not decrease the viability of bacterium Rhodococcus sp. 2012B. The bacterium remained resistant to all tested ND concentrations (0.25, 0.5, 5, and 10 mg/mL). It is found that Rhodococcus sp. 2012B is able to maintain its population size during the absence of alternative carbon sources in the presence of even small ND concentrations in the medium. It was determined that the number of viable cells of Rhodococcus sp. 2012B increased almost two times in the presence of high ND concentrations in the presence of an other available carbon source. Thus, bacterium Rhodococcus sp. 2012B can be considered a potential biodestructor of detonation nanodiamonds. PubDate: 2018-07-01
Abstract: Abstract The structure of nanocomposites based on opal matrices with different types of filling of structural voids is investigated. It is shown that the order in which tetrahedral and octahedral voids in the opal matrix are filled with various substances affects the X-ray diffraction pattern in the small angle region. On the basis of neutron diffraction, small angle X-ray scattering, and transmission electron microscopy data, models are proposed for filling the voids. The structural parameters of ordered nanocomposites based on opal matrices of different compositions are determined. PubDate: 2018-07-01
Abstract: Abstract The aim of this work is to study the possibility of removing antimicrobial peptides arenicin-1 and tachyplesin-1 from aqueous solutions using new highly hydrophobic nanomaterials—carbon nanotubes (CNTs) Taunit-M. Two types of CNTs, respectively, functionalized and nonfunctionalized with–COOH groups are studied. The RP HPLC method is used for the quantification of peptides in solutions before and after the sorption on the CNTs. It is revealed that tachyplesin-1 and arenicin-1 are actually not adsorbed on nonfunctionalized CNTs. A theoretical calculation of specific hydrophobicity and aliphatic index shows that both peptides have poorly expressed hydrophobic properties, and this can explain lack of their adsorption. On the contrary, using functionalized CNTs makes it possible to remove up to 89% of arenicin-1 and 92% of tachyplesin-1 from the solution. A comparative study of adsorption of the antimicrobial peptide tachyplesin- 1 on nonfunctionalized activated carbons and functionalized CNTs shows that the amount of peptide adsorbed on activated carbons is about three times less than that absorbed on CNTs. It is assumed that the high adsorption capacity of the functionalized CNTs toward the studied peptides results from the functionalization of the sorbent surface with the–COOH groups capable of forming ionic bonds with free–NH2 groups of peptides. This shows the prospects for using functionalized CNTs as sorbents for the removal of toxic preparations of peptide origin from aqueous solutions. PubDate: 2018-07-01
Abstract: Abstract Complexes of spherical gold nanoparticles with antibodies, obtained by direct adsorption and indirect (nanoparticle–anti-species antibody–specific antibody) interaction, were studied. The binding processes for nanoparticle-labeled antibodies in immunochromatographic analysis (ICA) and competitive detection of low molecular weight analytes are considered. Based on the developed mathematical model, the advantages of indirect labeling of antibodies are shown; the parameters determining the gain in the detection limit between two kinds of systems are characterized. The obtained complexes of gold nanoparticles with antibodies were used for the development of ICA for antibiotics. The reached detection limit of ampicillin ICA is 100 ng/mL for direct labeling and 16 ng/mL for indirect; in the case of tetracycline, these values are equal to 4.2 and 1.3 ng/mL, respectively. PubDate: 2018-07-01
Abstract: Abstract The influence of WS-120 white soot nanoparticles and ultrafine particles of powdered quartz (brand A) with the same chemical nature (SiO2) and size (diameter of ~150 nm) on the structure and impact strength of dispersedly filled epoxy polymers is elucidated. This is the first time that agglomerates of white soot nanoparticles with sizes of ~150 nm at their optimal concentration have been shown to almost double the impact strength of epoxy polymers, while its initial value under the effect of monolithic ultrafine particles of powdered quartz with ~150-nm particles gains only ~20%. Agglomerates of nanoparticles with optimal dimensions are found to be much more efficient for increasing the impact strength of epoxy dispersed systems in comparison with monolithic ultrafine particles. PubDate: 2018-07-01
Abstract: Abstract The strong dependence of cytotoxicity of Keggin heteropoly acids [XM12O40]n–, X = Si or P, M = Mo and W, n = 3 or 4 on chemical composition is demonstrated using the example of human embryo fibroblast cells based on the results of diagnostics using impedance monitoring, scanning electron microscopy, and measurements of visible cell sizes. The explanation of this dependence based on the role of hydrolytic stability of multiply charged anions in the development of cytotoxicity of these compounds is suggested. The results make it possible to suggest a new mechanism for the development of selectivity of polyoxometalate cytotoxicity relative to the studied cells. The differentiated cytotoxic activity of polyoxometalates relative to oncogenic cells is predicted. PubDate: 2018-07-01
Hybrid journal (It can contain Open Access articles)
[2570 journals]
