A I Blesman's research while affiliated with International Council on Nanotechnology and other places

The development of mycotic colonization of the base surface with further biodegradation of acrylic plastics is currently of undoubted interest. The oral cavity is a favorable ecological niche for colonization by fungi and their subsequent possible invasion into the epithelium of the oral mucosa. The method of modulation interference laser microscopy is of considerable interest to researchers in medicine in the context of obtaining the necessary information about the morphological characteristics of microbial cells and the microbiome community as a whole during the colonization of a certain ecological niche in the human body. Purpose of the study: to analyze the microrelief of the biofilm of yeast-like fungi of the species Candida albicans of base plastics of the hot type of polymerization using the method of laser modulation interference microscopy. An experimental study was carried out in order to study biofilms of yeast-like fungi of the genus Candida on samples of basic plastics, an image of a biofilm of yeast-like fungi of the species Candida albicans was obtained on the surface of a plastic of a hot type of polymerization (polymethyl methacrylate) in the visualization of the phase portrait, a description of its horizontal and vertical bioprofile. As a result of the research, the heterogeneous structure of the biofilm was determined, due to the different density and accumulation of cells along the surface, the characteristics of the surface were established in accordance with the roughness criteria. The microrelief parameters on a separately arbitrarily selected section line allow one to determine the characteristics of the biofilm in the required area and make it possible to judge the nature of its formation in a certain biological niche.

This work reports the appearance of iridescent spectral patterns in the form of coloured stripes on AISI 321 steel surfaces subjected to ultrasonic impact treatment (UIT). The possible reasons for the UIT-textured surface coloration are considered from the viewpoints of wave (diffraction and interference) optics. According to the XRD analysis, the phase composition of the AISI 321 steel surface layer after UIT is represented by the austenite and martensite iron phases. The chemical composition of the UIT-textured steel near-surface layer is identified using XPS, which includes iron and chromium in the oxidised and metallic states. The thickness of the oxygen-enriched layer after UIT is estimated to be approximately 15 nm. SEM and AFM analysis confirmed that UIT provides the formation of periodic surface structures with characteristic dimensions from several hundreds of nanometres to several micrometres coinciding in order of magnitude with wavelengths in the visible range. Applying different processing modes of AISI 321 steel surface leads to qualitative transformations in the spectral patterns: the position of the coloured stripes, its width, and the total number of the observed diffraction maxima change according to the equation of light diffraction. The obtained results indicate that diffraction of light is the main reason for the appearance of spectral patterns on the UIT-textured AISI 321 steel surface, which is analogous to a reflective diffraction grating. Structural diffraction coloration could be used as a possible basis for a non-destructive spectral control for UIT-textured steel surfaces and indirect monitoring of the performance of UIT equipment.

Creation of osteoinductive materials based on biocompatible synthetic salts, with a sufficiently high strength and porosity, with the shape which allow filling bone defects with various shapes and sizes is an actual task of modern biomaterial science. In this work, a series of granular materials were obtained from synthetic powders with various proportions of hydroxyapatite and wollastonite using a suspension technology based on the principle of immiscible liquids. Ceramic particles have a spherical shape, microhardness at least 17 HV and open porosity about 50 %. These materials can be used for reparation of bone defects of various locations, shapes and sizes in surgical dentistry, traumatology and orthopaedics.

Wire electrical discharge machining (WEDM) is widely used in various fields of production. Its disadvantages include a relatively low productivity rate caused by wire breakages among other factors. In this article, the method of fractographic analysis is used to study a wire that has undergone a breakage during machining. The results indicate that the tool–electrode is subjected to mechanical tension followed by a ductile fracture. The most probable reason of wire breakages is a decrease in the wire cross–section, which can be caused by an electrodes short circuit.

The paper studies the effect of parameters of a thin-layer copper-based coating applied by magnetron sputtering on the wear resistance of samples made of steel 18Cr2Ni4WA when working in a friction pair “18Cr2Ni4WA – cast iron GG 15”. The rational values for the thickness of the applied copper coating are determined, at which the lowest friction torque during the burn-in period and the minimum burn-in time are achieved. Jeol JCM-5700 Scanning Electron Microscope is used to study the friction track of samples and counter bodies. It is found that in the process of friction, the coating is selectively transferred from copper to the surface of the counter body, which significantly reduces the wear of the counter body.

The paper presents the results of the investigation devoted to the influence of wire electrical discharge machining modes on crack formation and surface layer morphology of the titanium alloy. The aim of the paper is to obtain interrelation data about processing modes with depth of microcracks penetration, as well as on the influence of processing modes on the morphology of the surface layer, in particular, on the group of parameters Rk. It is shown by using scanning electron microscopy that the depth of microcracks depends of the number of passes and processing conditions. The maximum depth is 12 μm after the first pass, the minimum is 0,9 μm after the fourth pass. The groups of parameters Rk study by the method of profilometry made it possible to conclude that the most favorable oil-retaining microrelief is formed after the third pass.

Probe device for electrical measurements of parameters thin doped films ZnO is considered. On the base of use of this probe device there is measured by the Hall E ffect method the concentration of electrons of the conductivity in indium doped thin films ZnO with thickness in the interval (0,065–0,3) μm concentration of electrons of the conductivity in the interval (2–3,4)∙1019 cm–3 and low mobility of electrons of the conductivity — (4–8,5) cm2 /B∙s. Dignity of probe device is a possibility of the reduction of the voltage asymmetry of hall probes.

Development of the composites based on substances with a high bioactivity potential is of current interest to medical materials science because composites' properties can be modified by varying the components ratios. Weakly crystallized calcium phosphates and calcium silicate hydrates, possessing higher chemical reactivity than their crystalline forms, are promising salts to be studied as biomaterials' constituents. In this study, precipitation from aqueous solutions was employed to obtain apatite and calcium silicate hydrate composites. Synthesized solids were examined without high-temperature thermal pretreatment using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), laser diffraction, physical adsorption (BET method) and thermogravimetric analysis coupled with the mass spectrometry (TGA/MS). Compositions containing poorly crystallized carbonate-substituted hydroxyapatite, calcium silicate hydrate and calcite as an admixture were obtained by varying concentrations of the reagents. Soaking of the composite ceramics formed from freshly precipitated synthetic solids in simulated body fluid (SBF) at 37 °C for 14 days lead to formation of the surface layer of amorphous calcium phosphate. As the calcium silicate content in the composites increases, the coating's density and thickness also increase, because silicate ions act as active sites in the process of new phase nucleation. Furthermore, prismatic calcite crystals were identified to form on the lower side of ceramics. This may be caused by an increasing of local supersaturation with respect to calcium carbonate in small-volume confinement conditions during the experiment.

Composites based on several biocompatible inorganic compounds present oneself a class of promising materials that can be used to repair damaged areas of hard tissue. Development of these composites and their bioactivity establishing is paid a significant attention. Investigation of processes occurring at composite powder materials soaking based on poorly crystallized carbonate substituted hydroxyapatite and calcium silicate hydrate in Tris-buffer was performed in this work. Chemical composition analysis of solutions contacted with composites with varying calcium phosphate and calcium silicate contents was carried out. Examination of undissolved solid phases was performed by SEM, FTIR and LDA. The obtained results indicate that materials components gradually dissolve in Tris-buffer. Moreover, the samples resorption rate increases with the growth of calcium silicate hydrate content in materials composition. Precipitation of the apatite was repeatedly detected in experimental conditions; it designates a potentially high bioactivity of investigated synthetic mixtures.

This paper provides the results of UIT modes influence on adhesive properties of the surface layer of AISI 321 austenitic stainless steel. The purpose of the study was to determine the adhesion force of the samples surface processed with a varying static load of an ultrasonic instrument and its relative travel velocity to the sample. The adhesion force was experimentally detected via atomic force microscopy from the force curves of the probe retraction. In this study it has been established that ultrasonic impact treatment of AISI 321 steel does not significantly affect the adhesive component of friction force.