Vol 14, No 11-12 (2019)

The creation of implantable devices that support the functioning of the body is an important area in the field of medical technology. Many of these devices require a power supply, and it is desirable that such sources work during the entire period of implantation, even in the case of a lifelong implant installation. The published data on energy sources for powering implantable and wearable medical devices is reviewed. A comparative assessment of the characteristics of biofuel cells as the most developed version of an implantable energy source with other renewable sources of electric energy based on thermo-, piezo-, electrostatic (ES), magneto-, and photo-converters is given. Particular attention is paid to the use of implantable devices that can serve as a source of energy for low-power systems: micropumps, pacemakers, neuroimplants, etc.

An electrodynamic model of the redox sorption of oxygen from water on metal-ion-exchange nanocomposites’ (NCs) granular layers is proposed. It features a simultaneous description of the oxygen reduction process along the electrochemical and chemical routes. Due to the inhomogeneous oxidation of metal nanoparticles by oxygen, the granular layer of the NC ohmic resistance, which varies in height and time, is taken into account. The adequacy of the model was tested on a copper-containing NC.

In this paper, the possibility of synthesizing multiwalled carbon nanotubes (CNTs) by DC arc discharge plasma in ambient air is shown. The synthesis takes place in a graphite cathode with a crucible shape using tungsten powder as a catalyst. In the non-vacuum synthesis method the CO atmosphere is generated in the reaction zone during the arcing, preventing the products of the synthesis from oxidation. According to the X-ray diffraction analysis (XRD), the synthesized product includes more than 85 vol % of carbon crystalline phases with a graphite-like structure, a cubic tungsten phase, and two phases of tungsten carbide WC and W₂C. The transmission electron microscopy data shows that the product of the synthesis contains CNTs with a relatively large number of walls (up to ~50 pcs) (MWCNTs) with a diameter of up to ~100 nm and a length of up to ~1.5 μm. It was found that crystalline objects corresponding in structure to WC tungsten carbide are identified inside CNTs.

Cobalt(II) salts are synthesized from saturated monocarboxylic acids: formic, butyric, valerianic, caproic, enanthic, and caprylic acids. The resulting compounds are characterized by elemental analysis, IR spectroscopy, thermogravimetry, and differential scanning calorimetry. As a result of the thermal decomposition of the synthesized carboxylates and cobalt acetate, cobalt-containing nanocomposites are obtained. The obtained nanocomposites are studied by elemental analysis, IR spectroscopy, scanning and transmission electron microscopy, energy dispersive X-ray spectroscopy, and X-ray phase analysis. Magnetic studies of the obtained nanocomposites are carried out.

The experimental study results of synthesizing molybdenum carbide in a plasma of a direct-current arc discharge by the vacuum-free method are presented. The influence of the current amplitude of the discharge circuit on the phase composition of the synthesis product is established. The synthesis product contains a microdimensional component and a nanosized one. The scanning electron microscopy (SEM) and X-ray diffractometry methods identified carbon fibers with a graphite structure and modified fibers containing graphite and molybdenum carbide as part of the microsized component. The nanoscale component contains clusters of particles that are a graphite matrix in which molybdenum carbide particles are immersed.

Research is conducted on the development of paper packaging materials with antibacterial properties using titanium dioxide nanoparticles. Titanium dioxide nanoparticles are synthesized by the hydrolysis of titanium tetrachloride in an alkaline medium, adjusting the pH value with an aqueous solution of ammonia at a temperature of 30 to 60°C. The influence of reaction conditions on the synthesis of titanium dioxide nanoparticles and the pH of the medium are studied and the optimal synthesis conditions are found. The processing parameters of paper packaging materials with aqueous solutions of titanium dioxide nanoparticles, which give them antimicrobial properties, are determined. Using electron-scanning microscopy and energy dispersive microanalysis, it is shown that untreated packaging paper contains 64.69% of C and 35.31% of O; after modification with a solution of titanium dioxide nanoparticles, titanium dioxide particles, which are distributed quite unevenly depending on the initial concentration of titanium dioxide nanoparticles, form on 16.46–21.14% of the surface of the treated paper. The packaging materials modified by the proposed composition show strong resistance to the action of microorganisms. The use of the developed antimicrobial food packaging reduces losses and preserves the quality and safety of food products during transportation, storage, and sales.

Application of advanced nanotechnologies is one of the main ways to increase crop yields in order to meet the growing global demand for food. This paper investigates the effect of Fe and Zn nanoparticles (NPs) on seed germination and growth of spring wheat seedlings (T. aestivum L.) of the Zlata cultivar, as well as leaf anatomical changes, yield, grain quality, and microelement composition of the soil after harvesting. It was found that presowing seed treatment by a composition of Fe NPs at a concentration of 10^–5% and Zn NPs at a concentration of 10^–4% contributed to a 27% increase in the seed germination energy index and root weight compared to the control. The highest plant height (by 8.2%) and green mass (by 8.5%) were observed in the experimental variant with presowing seed treatment by Zn NPs. The leaf area after presowing seed treatment by iron and zinc NPs increased by 18.2 and 33%, respectively. The highest index of specific leaf area (28% higher than the control), calculated as the ratio of leaf area to green mass, was observed in wheat leaves after seed treatment by Zn NPs. Presowing seed treatment by Fe and Zn NPs separately or in combination led to changes in anatomical parameters (leaf, mesophyll, and epidermis thickness, and conducting bundle area), which were higher than those in the control group of plants whose seeds were treated with water and lower than those in leaves of the plants whose seeds were treated with polymers. Evaluation of the wheat yield structure and grain quality after presowing seed treatment by the composition of metal NPs showed a greater thousand grain weight (1.9 g more than the control) and a higher grains/ear ratio. Presowing treatment of spring wheat seeds by Fe : Zn NPs contributed to higher content of mobile forms of iron, zinc, copper, and phosphorus in the soil after harvest.

The prevalence of antibiotic-resistant microorganism strains requires us to search for new antibacterial medicines. The study of the antibacterial effect of metal nanoparticles is mostly dedicated to ultradispersed silver and copper powders, while the antimicrobial activity of nickel nanoparticles is under researched. There are a number of studies suggesting a correlation between metal nanoparticles’ antibacterial activity and their physical and chemical properties. The physical and chemical properties of nickel nanoparticles are studied and oxide film ensuring a prolonged effect of the agent is found on the metal surface. It is shown that nickel nanoparticles form large (1145.00 ± 89.60 nm) agglomerations. Individual nanoparticles are as large as 80.51 ± 2.21 nm. The effect of nickel nanoparticles on the Staphylococcus epidermidis and Escherichia coli clinical strains is studied. The pronounced antibacterial effect of metal nanoparticles dependent on their concentration and exposure time is observed. The research of the potential of the microorganism cell ζ-zeta proves the metal nanoparticles’ adhesion on the surface of a microbe cell due to electrostatic stress. The effect of nickel nanoparticles on Gram-negative and Gram-positive microorganisms’ cell metabolism is estimated and the decrease in the saccharolytic activity of E. coli clinical strains, as well as the reduction of S. epidermidis strains able to turn nitrates into nitrites, is shown.

This paper proposes a method of one-step synthesis of a magnetic nanocomposite based on hydroxyapatite and iron oxide using the modified stoichiometric titration method. The possibility is shown of modifying the proposed method for one-step synthesis of the magnetic nanocomposite containing bioactive compound (BAC) from a 2-arylaminopyrimidine series. The composition, morphology, structure, and magnetic characteristics of the nanocomposites with and without BAC have been evaluated. The kinetics of the BAC release in a solution simulating the stomach environment has been studied. The reported composite is promising for biomedical applications as a tool for targeted drug delivery.

Magnetic field sources are developed and manufactured for experiments in order to activate neuron channels. The designed cryogenic magnetic systems are part of an experimental research stand for remotely controlling neuron expression by static and low-frequency (up to 100 Hz) magnetic fields. The devices are capable of producing an induction field value of ~0.5 T at the liquid nitrogen temperature (77 K); and when working with subcooled liquid nitrogen (70–65 K), the induction field value is above 1 T. The relevance of using the most promising materials—second-generation high temperature superconductors—in the cryomagnetic system is underlined.