Yu. K. Danileiko

Study of the structural and physicochemical properties of nanostructured zirconia crystals for fabricating an innovative electrosurgical tool

To optimize the chemical composition of the crystals of nanostructured partially stabilized zirconium dioxide for fabricating cutting parts of an electrosurgical tool, the structural and strength properties of these crystals were investigated in dependence on the stabilizing impurity (Y2O3) content and the effect of additional dopants on the critical properties of the material was studied. It was established that in all the investigated crystals without additional doping, regardless of the stabilizing impurity content, there are two phases of zirconium dioxide tetragonal modification with different tetragonality factors, c/a = 1.006–1.007 and 1.014–1.015, the first being nontransformable and the second being transformable to a monoclinic phase. All the synthesized crystals are characterized by a pronounced twin domain structure, which forms upon cooling the single crystal during the transition of the cubic structure to the tetragonal one. It was established that the Y2O3 concentration in the range from 2.5 to 3.0 mol % is optimal for ensuring high values of the strength characteristics and fracture toughness of the material. Doping of the crystals with the rare-earth elements notice-ably affects their strength characteristics. One of the most promising materials for fabricating cutting blades of the electrosurgical tool is the crystals of partially stabilized zirconium dioxide doped with Ce2O3+Nd2O3, which are characterized by high fracture toughness and enhanced bending strength.

Activation of reconstructive processes in rat tissues under the action of radiofrequency current with a periodic impulse mode of modulation

The action of a current in the radio frequency range with a periodic impulse mode of modulation on the activation of recovery processes in the skin and skeletal muscles has been studied. The action of a radio frequency current with a power of 1 W, as opposed to that of the weaker action (0.1 W) and stronger (4 W) action, leads to the activation of recovery processes in the skin and skeletal muscles. Recovery processes are manifested in the increase in proliferation and activation of angiogenesis in the skin, and also in formation of new muscle fibers. Recovery processes in muscles are accompanied by activation and migration of satellite cells of muscle tissue in the zone of action of the radio frequency current.

Spectral-luminescent investigation of absorption of phtalocyanine photosensitizers on a zirconia surface

Absorption on the surface of crystalline nanostructured, partially stabilized zirconia (PSZ) was studied by fluorescent spectroscopy. Water-soluble dissociable phtalocyanine derivatives of the anion and cation types were used as fluorescent markers. The Photosens luminescent dye was used in the case of the anion molecule, and Holosens was used in the case of the cation molecule. The absorption coefficients were evaluated by the method of comparison of the residual fluorescence of the dye solution after absorption of the crystalline powders of oxides under study (sapphire and PSZ) on the surface. It is shown that the adsorption ability of alumina (sapphire) is higher than that of zirconia (PSZ) by a factor of 6–8 for both the anionic and cationic molecules.

Diffusion of intrinsic defects in dielectric and semiconductor crystals with impurities

This paper reports on the results of detailed theoretical investigations into the diffusion of intrinsic defects in impurity crystals doped with mixed-valence ions. The special case of diffusion stimulated by variations in the redox properties of the atmosphere at the crystal boundary during high-temperature annealing is analyzed. The major consideration is given to the following fundamental problems: (i) the dynamics of valence transitions and the structure of the chemical reaction zone, (ii) the possibility of determining the type of chemical reaction at the crystal-atmosphere interface and the type of diffusing defects, (iii) the effect of dilatation mechanical stresses arising in the reaction zone on the reaction-zone structure and on the dynamics of diffusion processes, and (iv) the determination of the diffusion parameters of intrinsic defects and the constants of their interaction with impurity centers.

Optoelectronic element for control of spatial and time behavior of medical lasers

The strong angular and base dependence of the Fabry-Perot interferometer reflectivity is used for the increase of beam quality and power of medical lasers. The smaller divergency makes the use of thinner (more bendable) optical fiber possible.