Specific features of the heat transfer in nanostructures and methods of their investigation are discussed. Phonon heat conduction that is characteristic of semiconductors and insulators is considered. In nanostructures, the Fourier law is violated and the methods of classical theory of heat conduction are inapplicable. Analysis of the physics of heat-transfer processes has shown that the heat conduction of nanostructures depends on the shape and size of the sample, properties of its surface, and direction of the heat flow with respect to the nanostructure geometry. This fact has led to the development of radically new approaches to the determination of thermal conductivity of solids on the nano- and micrometer scales. Therefore, main attention is paid to the review of existing methods for finding thermal conductivity of nanostructures and the results of its theoretical and experimental determination. Various models of heat transfer in nanostructures are presented. The knowledge of statistical thermodynamics, kinetic theory, and solid-state physics is fundamental for this field of thermal physics.

Titanium membranes and meshes are used for the repair of trauma, tumors, and hernia in dentistry and maxillofacial and abdominal surgery. But such membranes demonstrate the limited effectiveness of integration in recipients due to their bioinertness. In this study, we prepared titania oxide (by microarc oxidation) and/or HAp (by electrophoresis deposition) coatings with alginate soaking. We used annealing at 700 °C for 2.5 h for HAp crystallinity increasing with achievement of an acceptable Ca²⁺ release rate. The feedstock HAp and prepared coatings were characterized by X-ray diffraction, IR spectroscopy, electron and optical confocal microscopy, and thermal analysis, as well as the in vitro study of solubility in saline and in vivo tests with the animal model of subcutaneous implantation (with Wistar rats). Biocompatible compounds were found for all deposited coatings. We noted that the best biological response was detected for the annealed Ca-P/TiO₂ bilayer with alginate binding. In this case, the coating crystallinity was ≈40.5-50.0%. The Ca²⁺ release rate was 2.042 ± 0.058%/mm² at 168 h after immersion in saline. Thin and mature tissue capsules with minimal inflammation and vascularization were found in histological sections. We did not detect any unwanted responses around the implants, including inflammation infiltration, suppuration, bacterial infections, tissue lyses, and, finally, implant rejection. This information is expected to be useful for understanding the properties of bioactive ceramic coatings and improving the quality of medical care in dentistry and maxillofacial surgery and other applications of titanium membranes in medicine.

The results of experimental studies of the nonequilibrium plasmochemical method for production of polycrystalline silicon from quartz are presented. It is shown that polycrystalline silicon in the form of spherelike particles with an average size of 100–200 μm and purity of 99.8–99.9% can be obtained with a yield of up to 60% using the electric arc installation developed.

Detonation spraying is thought to be a promising approach to producing calcium phosphate bioceramic coatings on various implants owing to the possibility of ensuring conditions that minimize undesirable thermal effects. In this work, this method has been used to produce coatings (up to ≈100 μm in thickness) based on nonstoichiometric hydroxyapatite (HA) with a Ca/P atomic ratio in the range Ca/P ≈ 1.45–1.50 on the surface of titanium substrates. Detailed characterization of the coatings by X-ray diffraction, Raman spectroscopy, and optical and electron microscopy has shown that, under the conditions of this study, the parent HA underwent a number of changes during the spraying process, which led to the formation of tricalcium phosphates (TCPs) (α-TCP and β-TCP) along with HA and amorphous phosphates. As a result, the Ca/P stoichiometric ratio increased (to Ca/P ≈ 1.65–1.67). Osseointegration effectiveness was evaluated in vivo by comparing biological reactions with control specimens (uncoated surgical screws) and coated screws using laboratory animals (Wistar rats). Histological and tomographic examination of ante- and postmortem materials showed that the coatings stimulated chondrogenic osteogenesis in the implant/bone contact region. These effects did not show up until 60 ± 5 days after implantation.

Obtaining new data on the gas-dynamic responses from the polymer samples (polytetrafluoroethylene, PTFE) irradiated by powerful VUV radiation from compressed plasma flows is in the focus of the present study. An erosion type magnetoplasma compressor (MPC), a type of plasma focus discharge, was used as a radiation source. The operating voltages of the MPC were between 15 and 25 kV, the maximum measured discharge current was 200 kA, and the radiation energy in the VUV range was ≈1–2 kJ. The VUV fluxes on the sample surface were high and equal to ≈10²²–10²⁴ photons cm⁻²·s⁻¹. Double-exposure laser holographic interferometry and schlieren photography were used to diagnose and visualize the gas-dynamic structures. The spatial distribution of the parameters (temperature, pressure and concentrations of electrons and ions) was defined based on the assumption of local thermodynamic equilibrium. It has been demonstrated that the maximum temperature ranged from ≈ 10 to 15 kK in the plasma layer. The electron concentration was ≈ (0.7–1.6) × 10¹⁸ cm⁻³ in this region. The used techniques of optical diagnostics and procedures of result processing make it possible to obtain data on the dynamics of polymer ablation, which occurs when their surface is exposed to powerful energy fluxes (thermal, shock-wave, radiation, and other extreme loads).