Vol 11, No 9-10 (2016)

Spontaneous transformation in the aqueous solution of the metal-complex J-aggregates of the meso-methyl-substituted thiacarbocyanine into the metal-complex H-aggregates is studied. It is concluded that the transformation of aggregates is connected with a change in the structure of their primary aggregates from the monomer packing of the “brickwork” type to packing of the “ladder” type.

In this work we have studied the influence of ТiO₂ and Bi₂O₃ doping admixtures and impurities on the microstructure and properties of radio-absorbing Mg-Zn ferrites. The morphological peculiarities of inclusions of these admixtures in a ferrite ceramics are established. It is shown that the use of doping admixtures and impurities of these oxides makes it possible to control the frequency dependences of the magnetic permeability and dielectric permittivity of Mg-Zn ferrite materials. Examples of controlling the absorption spectra in a radio frequency range through variations in the composition of given radio-absorbing materials are presented.

The results of experimental research into ultrafine copper silicide production in plasma high-current pulsed arc discharge are shown. According to X-ray diffraction, the product consists primarily of η″-Cu₃Si (81%) and contains copper and silicon. A study of the material by transmission electron microscopy reveals the formation of elongated pointed copper silicide crystals with cross-sectional dimensions of approximately 250 nm. The presented method of preparation of copper silicide allow one to obtain grams of the ultrafine product per one operating cycle of the system, the duration of which is about 0.5 ms. The materials prepared may be used in the power industry, for example, for the manufacture of electrode systems of power supplies.

An original technology for the controllable production of catalytically active functional electrode nanocomposites based on porous silicon with bimetallic palladium–platinum nanoparticles is proposed. The nanocomposites are studied by electron microscopy, X-ray phase analysis, and cyclic voltammetry. The synthesized materials demonstrate high electrocatalytic properties in the direct formic acid oxidation reaction.

Synthesis conditions are optimized to obtain η-phase/zeolite and Hombifine N/zeolite nanocomposites by the modified cold-impregnation method (method 1), which consists of the codispersion of the samples containing the η-phase or Hombifine N with nano-anatase in a dilute KOH solution, and Beta(25) and ZSM-5 zeolites with different modulus, MOR and Y, for the first time, as well as by the TiO₂/zeolite in situ method (method 2), which consists of the addition of zeolites into the reaction mixture during the synthesis of titanium dioxide. The starting components and nanocomposites are characterized by different methods, such as wide- and small-angle Х-ray scattering, scanning electron microscopy, and low-temperature nitrogen adsorption (the Brunauer–Emmet–Teller method). The interaction between nanosized titanium dioxide (NTD) and zeolites (except Y) during the formation of the NTD/zeolite nanocomposite (method 2) and the η-phase/MOR nanocomposite (method 1) is revealed, and the presence of NTD in the nanocomposites in nanocrystalline (Hombifine N/zeolite) or amorphous (η-phase/Beta(25) and η-phase/ZSM-5(300)) states is established. It is found that the use of microwave and ultrasonic treatment upon the synthesis of the nanocomposite gives rise to the uniform distribution of spherical particles in the samples; furthermore, they are the same size (η-phase/ZSM-5(12), η-phase/ZSM-5(300), and η-phase/Y) or smaller (η-phase/MOR, η-phase/Beta(25), and η-phase/ZSM-5(40)) when compared to the original η-phase. The size of spherical particles in the η-phase/ZSM-5(40) nanocomposite is comparable with the starting ZSM-5(40) zeolite. It is found that the preparation of nanocomposites by method 2 leads to an increase in the specific surface for the NTD/ZSM-5(12) and NTD/Y nanocomposites and to a decrease in the specific surface for the remaining nanocomposites (most significantly for NTD/MOR) when compared to the zeolite matrix, and promotes the high adsorption capacity of the NTD/zeolite nanocomposites with regard to the extraction of the P(V) ions from the model aqueous system with the maximum value (99.48%) for the NTD/MOR nanocomposite.

The paper investigates sorption of 2-mercaptobenzothiazole (MBT) and zinc ions by 1D carbon nanostructures (CNS) of different morphologies. It was found that the organization of graphene planes in the body of the CNS and pre-activation of the nanomaterial with ultrasound determine the nature of the interaction with functionalizator and the value of adsorption. It is shown that the functionalization products affect complex of physico-mechanical properties of the rubber compositions and vulcanizates. This can be used for obtaining a rubber with high fatigue endurance and with increased frost resistance.

A solution-processable approach to designing molecular silicasol-based barrier coatings for organic electronics has been developed. The barriers are assessed by the optical calcium test and demonstrate water-vapor permeation rates of about 10^–2 g m^–2 day^–1. Silicasols are shown to be promising for the encapsulation of organic electronics devices, for which the resulting water-vapor permeation rates are sufficient (e.g., for organic field-effect transistors).

Features of the formation of periodic 2D and 3D opal-like structures depending on the conditions of deposition have been investigated in this work. The subject of the experiments is aqueous dispersions of poly(methyl methacrylate) submicron particles with a narrow size distribution. The particles are precipitated by sedimentation, centrifugation, and the meniscus method. The samples are studied using electron microscopes. Significant morphological differences in periodic structures obtained by various methods are found.

Nanoscale colloidal silver (NCS) is one of the most popular products of nanotechnology and is widely used in cosmetics, food supplements, and other types of consumer products. The aim of this work is to study the influence of NCSs orally introduced into rats during an experiment lasting 92 days on some indicators of homeostasis of essential and toxic trace elements. The Argovit-C NCSs produced by Vector Vita LTD, Novosibirsk, Russia with silver (Ag) nanoparticles of the diameter in the range of 5-80 nm according to transmission electron microscopy and dynamic laser light scattering. The drug is introduced into growing male Wistar rats in doses ranging from 0.1 to 10 mg/kg body weight (b.w.) for 1 month by gavage and then with a diet consumed for 62 days. The control animals receive deionized water or an aqueous solution of the stabilizer polyvinylpyrrolidone. The content of Ag, cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), and zinc (Zn) in the liver, kidneys, and spleen is determined by mass spectrometry with inductively coupled plasma; selenium (Se) in serum and urine is measured by spectrofluorimetric method and glutathione peroxidase activity by the enzymatic spectrophotometric method. The dose-dependent accumulation of Ag in the animal liver at a dosage ranging 0.1–10 mg/kg b.w. and kidney and spleen in the range of 0.1–1 mg/kg b.w. is revealed. A significant decrease in the content of Cu in the kidneys; a decrease in Zn and Co content and increase in Mn content in the liver; and an increase in Cd, Cr, and Ni in spleen of animals receiving NCS at various doses are found. A significant positive correlation is found between the levels of Ag and Cd, Ni, Cr in the spleen, and a negative one is found between Ag and Cu in the kidneys. Indicators of Se provision (urinary excretion, the content in the blood plasma, the activity of glutathione peroxidase) are significantly lower in rats receiving NCS at a dose of 1.0–10 mg/kg b.w. Thus, NCSs, entering the body through the gastrointestinal tract at a dose of silver of at least 1 mg/kg b.w. may affect the homeostasis of essential and toxic trace elements. The antagonism of Ag (as part of the NCS) and Se in the composition of the diet should be taken into account in assessing the safety of widely used food supplements–sources of colloidal Ag.

The production of nano-bentonite and its effects on mutation process in the strains of Salmonella typhimurium are studied. It is revealed that nano-bentonite particles essentially differ from bentonite particles in structure, size, and shape. Bentonite particles are cone-shaped and 0.3 to 1.0 μm in size, whereas nanobentonite nanoparticles are oval-shaped and 25 to 95 μm in size. Single particles (less than 10.0%) are irregular polyhedra and 0.6 μm in size. The structure of bentonite consists of separate fragments of constituent minerals composed of packages–lamelee 0.6 μm in size cemented with an amorphous mass. An amorphous mass containing single micrometer-sized packages–lamelee is observed in the structure of the nano-bentonite. It is determined that nano-bentonite does not possess mutagenic activity on microorganisms. The study of antimutagenic potential of nano-bentonite reveals that it possesses a moderate inhibitory effect on mutagenesis caused by mitomycin C, 2,4-dinitrophenylhydrazine, and ethyl methanesulphonate, but does not inhibit genotoxic potential of hydrogen peroxide. The results demonstrate that nano-bentonite is nongenotoxic and can be used for the development of next-generation safe nanotechnological materials.