Vol 14, No 3-4 (2019)

A method for determination of mercury(II) using polyurethane foam modified on the surface with silver triangular nanoplates that have an average edge length of 52 nm and thickness of 4 nm is developed. The method is based on the oxidation of silver nanoplates with mercury(II). This process is accompanied by a decrease in the surface plasmon resonance band of nanoparticles which allows us to consider the nanocomposite material as a solid-phase analytical reagent for the determination of mercury(II). The influence of the reaction time and pH on the sensitivity of mercury determination is studied. The detection limit of mercury under the selected conditions is equal to 50 μg/L; the range of determined contents is 150–1000 μg/L. The increase in the volume of the analyzed solution from 5.0 to 100.0 mL via concentration reduces the detection limit of mercury to 5 μg/L.

Structure, phase composition, and mechanical properties (microhardness within indenter penetration depths of 1200 nm ≤ h ≤ 6000 nm and fracture toughness) are studied on nanostructured zirconia ceramics (CaO stabilized) hardened with corundum and SiO₂ during accelerated aging under hydrothermal conditions (T_ag = 134°C, P = 3 atm, H = 100%, 0 ≤ t_ag ≤ 25 h). The use of CaO as a stabilizer of the zirconia tetragonal phase (instead of “conventional” Y₂O₃) promotes increasing resistance to hydrothermal effects of composite ZrO₂ + Al₂O₃ and ZrO₂ + Al₂O₃ + SiO₂ ceramics. The reached fracture toughness (more than in 40%) via introduction of silica (\({{C}_{{{\text{Si}}{{{\text{O}}}_{2}}}}}\) = 5 mol %) increase provides a satisfactory hardness/fracture toughness (H = 12.3 GPa, K_C = 6.66 MPa m^1/2) ratio of the Ca–ZrO₂ + Al₂O₃ + SiO₂ composite ceramics even after its accelerated 25-h aging.

Comprehensive studies combining X-ray structural analysis, structural dynamic measurements with an EPR probe method, thermophysical measurements (DSC), and scanning electron microscopy have been carried out. The specificity of the crystalline and amorphous structure of ultrathin poly-3-hydroxybutyrate fibers containing a low concentration of manganese complex with chlorotetraphenyl porphyrin (MnCl₂–TPP) (0–5 wt %), obtained via electroforming, is considered. When PHB of MnCl₂–TTP complexes are added to PHB fibers, the morphology of the fibers changes, crystallinity increases, and the molecular mobility in the dense amorphous regions of the polymer slows down. The temperature effect on the fibers (annealing at 140°С) leads to a sharp increase in crystallinity and molecular mobility in the amorphous regions of poly-3-hydroxybutyrate. Exposure of fibers in an aqueous medium at 70°С leads to a sharp decrease in the enthalpy of melting and to an increase in the molecular mobility of the chains in the amorphous regions. The fibrous materials have bactericidal properties and must be directly applied in the creation of therapeutic systems with antibacterial and antitumor action.

The widespread occurrence of anemia and the presence of side-effects of existing iron-containing drugs require the search for new drugs. In an experiment on male rats of the Wistar strain, posthemorrhagic anemia is simulated by collecting blood from the tail vein in an amount of 1.5% of body weight. Intramuscular administration of iron–molybdenum polyoxometallates in an amount of 1.5 mg/kg to rats with anemia results in a faster restoration of the content of red blood cells and hemoglobin, the hematocrit value in the blood, the concentration of iron in the blood plasma, and the content of erythrocyte precursors in the bone marrow, which recover one to seven days earlier than the parameters measured in a control group of untreated animals.

Gallium nitride (GaN) seed sub 100 nm layers deposited from triethyl gallium and ammonia on sapphire substrates in different modes during atomic-layer epitaxy (ALE) have been studied via scanning electron microscopy (SEM) and spectral ellipsometry. The seed layers are island films with different degrees of substrate surface coating, which consist of GaN crystallites having different sizes and average thicknesses from 10 to 40 nm. A program for processing SEM images has been developed, which allows us to quantitatively estimate areas of particles, inclusions, and phases present in films and on the substrate surface. The technique of processing the results of spectral ellipsometric measurements of island films composed of GaN crystallites on sapphire substrates using the Maxwell–Garnett model reveals the same tendency in the area of substrates coated with the films as the processing of SEM images. The developed program and technique made it possible to determine the optimal mode (among six implemented) of ALE of GaN seed layers on sapphire substrates for preparation of high-quality HEMT structures. They can also be efficiently used for studying any island films, layers with inclusions of physical and chemical phases, and systems of colloidal particles used for formation of microelectronic structures.