Vol 13, No 4 (2019)

X-ray multiple-wave interaction in a paratellurite crystal (TeO₂) under modulation of the crystal lattice by low-frequency ultrasonic vibrations is studied. The use of such vibrations enables accurate scanning or tuning of the multiple-wave region of X-ray interaction.

The morphological, dimensional, and spectral characteristics of hybrid polymeric nanosystems based on nanoparticles of zero-valent selenium and silver stabilized with zosterin and methylcellulose are determined by methods of atomic-force microscopy, dynamic light scattering, and UV-vis spectroscopy. The possibility of changing the morphological parameters, as well as the dimensional and spectral characteristics of hybrid polymeric nanosystems by varying the nature of nanoparticles and bioactive polymer stabilizer is shown.

The results of a cross-correlation analysis of the relationship between the process conditions for obtaining CoNiFeSiB amorphous alloys, their physical and chemical properties and structure are presented. The alloys are obtained by single-roll rapid quenching on a copper wheel at frequencies from 30 to 60 Hz, which corresponds to linear velocities from 22 to 38 m/s, a chamber pressure from 0.05 to 0.6 atm, and a pressure in the crucible from 0.4 to 0.6 atm. Elemental analysis is carried out; the atomic and surface structures, phase-transition parameters upon heating, and the corrosion properties are investigated. Correlations between the structural-ordering parameters and physical and chemical properties are determined. Regression models of the dependence between the structural characteristics, physical and chemical properties, and process conditions of production are formulated. A regression model for the dependence of the average cluster area in the atomic image on the specific energy of structural changes is proposed. The concentrations of nickel, silicon, and boron in cobalt-based alloys are found to play an important role in determining the structural characteristics and properties of the alloys.

Using the small-angle neutron scattering method, the effect of conducting carbon additives (carbon black, graphene, and carbon nanotubes) on the porous structure of positive electrodes based on lithium iron phosphate (LiFePO₄) is studied. To separate scattering at closed pores from scattering at open pores, the electrode is wetted with a deuterated electrolyte, which makes it possible to compensate for the scattering at open pores. The used additives are found to change the electrode porosity to different extents and affect the wettability of the material both through a different efficiency of the incorporation of the initial material into pores and due to a change in the matrix of lithium iron phosphate.

The effect of nanosecond high-power ion beam treatment on layers of organic polymers: chlorinated polyvinyl chloride, polyvinyl chloride, polyvinyl chloride + polyvinylidene chloride, vinyproz (vinyl chloride and methyl methacrylate copolymer), polyvinyl acetate, and polyvinylidene fluoride, containing a catalytic additive of inorganic and organic iron compounds, is investigated. The formation of carbon nanofibers with a diameter of 30–150 nm and a length of up to 10 μm on the surface of chlorine-containing polymers and their compositions under exposure to a high-power ion beam is observed. The formation of carbon nanofibers on the surface of other polymers under study after exposure to a high-power ion beam is not observed. A possible mechanism of the effect of the nature of the polymer on the formation of nanostructured carbon on the surfaces of the studied polymers under the action of a high-power ion beam is discussed.

The processes of the propagation of quantum and classical charged particles through porous films are studied. The propagation of quantum particles is analyzed by numerically calculating the Schrödinger equation. The polarization force acting on the charge is calculated within the framework of classical electrodynamics. The possibility of pore formation in the films is analyzed in the problem of the propagation of ions with large charges through ultrathin carbon films. Mathematical modeling of the film accompanied by elucidation of the most important polarization properties is carried out to understand the process more clearly. The calculations show the possibility of film perforation because of the action of ponderomotive forces generated by the strong polarization field of the wave packet of the passing ion.

Titanium alloys approved for clinical application are used to manufacture various endoprostheses. Engraftment of the implant in bone tissue (osseointegration) is characterized by direct contact and functional connection between the implant and the bone tissue. The process of implant engraftment in soft tissue is characterized by fibrointegration, i.e., interaction between the endoprosthesis material and soft tissue; as a result, connective tissue having a fibrous structure is formed on the endoprosthesis surface. The process of the engraftment of titanium implants greatly depends on the properties of the implant surface; therefore, to improve the efficiency of fibrointegration, various methods for modifying the implant surface are designed to impart them with the necessary biomedical properties. Implants with a polished surface, with surfaces of varying degrees of roughness, as well as those coated with titanium dioxide with the anatase structure are considered. The use of atomic force microscopy, scanning electron microscopy, and profilometry in studies of mesenchymal stem-cell adhesion and in vitro studies of implants with differently treated surface, which were embedded into the soft tissues of experimental animals, made it possible to determine the requirements for the optimal surface treatment of titanium implants used in maxillofacial surgery.

The interaction between a photon and a material particle (electron and atom) is considered in a reference system moving at the speed of light in vector-potential space. Based on Noether’s theorem it is shown that in vector-potential space the volumetric density of the photon energy, its velocity, and the ring current density of a material particle are retained. Based on solution of the Schrodinger equation for a photon and an electron interacting in vector-potential space, it is shown that during the interaction the electron should represent a quantum oscillator with a discrete set of energies. Electron fluctuations or Dirac’s electron jitter occur at the speed of light. The problem of the appearance of the magnetic moment (spin) of an electron in vector-potential space is considered. The conditions of the quantization of atomic currents in vector-potential space and also Heisenberg’s uncertainty principle in this space are presented. The Lamb frequency shift in the vector-potential space is found. A multiphoton system in the vector-potential space is investigated.

The principle of operation, the distinctive features and the possibilities of using Kirkpatrick–Baez and Wolter focusing X-ray optics are considered. Various optical schemes of Kirkpatrick–Baez optics (classical, confocal, and advanced) and various line ups of Wolter mirrors (“nested”, conical, and porous) are described. The possibilities and methods for eliminating optical aberrations are considered. Special attention is paid to the use of focusing optics in full-field X-ray microscopes and X-ray telescopes.

High energy resolution silicon semiconductor detectors are developed and used in RADIAN X-ray diffractometers. The use of these detectors reduces the requirements for monochromators and β-filters, simplifies the optical scheme of a diffractometer, increases the peak-to-background ratio, and decreases the radiation source power and sizes of a diffractometer. To select useful events, a tunable differential discriminator with a reconfigurable energy window is used in the detector. The detector can operate with different X-ray tube anode materials.

The use of ordered anodic aluminum oxide for nickel electrochemical deposition is studied. The conditions for aluminum anodization in a bath based on oxalic acid, thinning of the barrier oxide layer, and nickel electrochemical deposition from a sulfamate bath are described. The deposited nickel has a lattice constant of 3.51 Å and a texture in which the (100) grain planes are parallel to the surface. The surface morphologies of the anodic oxide layer and the upper and lower parts of the deposited nickel layers are examined using electron microscopy. The mean size of the oxide pores is 50 nm, the mean interpore diameter is 102 nm, and the oxide porosity is 21.5%. The surface topography of the bottom of the deposited nickel layer features a nanoscopic pattern formed by rods, which is identical in pore size and morphology to the oxide surface. The rod length is defined by the thickness of the anodic oxide layer formed on the aluminum-substrate surface. This feature is due to the homogeneous filling of oxide pores during nickel electrodeposition. We find that thinning of the anodic oxide layer to below 10 nm may impair adhesion of the oxide layer to the aluminum substrate and thus lead to nickel deposition on both sides of the oxide layer. The formation of dendrites is noted, and the possible causes of this as well as conditions favoring their growth are discussed.

The reflection coefficients and angular distributions of scattered particles under the bombardment of amorphous and crystalline tungsten targets by hydrogen and deuterium atoms are calculated. A reflection coefficient that is close to 100% is observed in the case of grazing angles of incidence on the crystalline targets. It is planned that tungsten in the form of polycrystalline plates will be used as the material for the ITER tokamak divertor. This phenomenon should be taken into account when calculating the energy input into the divertor.

The results of using a two-flux model of charged-particle transport in a substance are presented to describe the average energy of a monoenergetic electron beam passed through a film target with known composition and a given thickness. Formulas describing the distribution of the average energy of the electron beam over the target depth and the energy dependence of the electron-beam range for electrons with an energy of 0.1 keV–1.0 MeV are obtained. The results of calculating the electron ranges for a wide range of materials, namely, from Be to Au, are given. The particle ranges calculated using the formulas are compared with the experimental results of measuring the depth of their penetration into the target.

A computer study of the morphological characteristics of the AFM image of a self-organized system of surface hillocks in CZ n-Si (100) samples doped with zinc under conditions of hot implantation and oxidized at elevated temperatures is performed. Topological studies of the sample surface are carried out under ambient conditions using a scanning tunneling microscope in the atomic-force mode. Computer analysis of the AFM images of the surface is carried out using the STIMAN 3D software. The analysis made it possible to quantify the morphology of the hillock system on the substrate surface with respect to a number of parameters: the equivalent diameter, area, total area, and the shape factor both after Zn implantation and after annealing. Quantitative evaluation of the morphology of the system of surface hillocks will allow the nondestructive monitoring of the formation and evolution of nanoparticles in the subsurface layer of implanted samples during their heat treatment.

We study the effect of the microtopography of the surface of titanium implants on the proliferation (reproduction process) of fibroblast-like cells (cells of the connective tissue of the body) using the morphological analysis of cell cultures by phase-contrast microscopy. Three-dimensional titanium cell matrices (scaffolds) are used as the mechanical frame for the analyzed cells. The metabolic activity of the cells, cell viability, and the cytotoxic effect of scaffolds on human-skin fibroblast cultures are evaluated using the colorimetric MTT test. Titanium scaffolds with a polished surface and with a sandblasted surface and the same samples with a bioactive titanium-dioxide coating with the anatase structure are used in the experiments. The morphological analysis of human-skin fibroblasts in the presence of scaffolds does not show any changes in the appearance of the cells compared with control cells cultured in the absence of scaffolds. Evaluation of the cytotoxic effect of titanium scaffolds on the culture of human-skin fibroblasts show that none of the types of scaffolds used have a significant cytotoxic effect on the skin fibroblasts in the culture. It is concluded that the requirements for the surface treatment of titanium implants with high fibrointegration (formation of fibrous connective tissue on the implant surface), used in maxillofacial surgery, do not have an adverse effect on the proliferation of fibroblast-like cells and do not suppress their viability, since they do not have cytotoxic effects leading to cell death.

Using a set of structural-spectroscopic analysis methods, the relationships between the structure, morphology, and sorption characteristics of samples of nanocrystalline carbonate-substituted calcium hydroxyapatite synthesized with the use of a biogenic source of calcium (avian eggshell) by chemical precipitation from a solution are studied. Using X-ray diffractometry and X-ray microanalysis, impurities are found to enter the structure of the synthesized material from the avian eggshell, which leads to a change in the unit-cell parameters of the hydroxyapatite crystal without the formation of additional phosphate phases. Using optical spectroscopy and electron paramagnetic resonance, it is established that, as a result of the inheritance of a set of carbonate-ion impurities, a structure of B-type hydroxyapatite is formed. An increase in the content of the PO₄ phosphate groups during the process of synthesis of materials in the atmosphere results in a decrease in the content of structurally related CO₃ groups. A decrease in the pH of the solution at the synthesis stage, due to an increase in the content of \({\text{PO}}_{4}^{{3-}}\) anions, affects the morphology of the samples by increasing the size of defects, i.e., nanopores on the surface of the nanocrystals. Such a change in the morphology of the materials results in changes in the sorption characteristics of the samples, determined by the method of the thermal desorption of nitrogen. The specific surface area of the powders is ~55.5 ± 0.9 m²/g, which many times exceeds known analogs. Despite the developed surface, the samples of carbonate-substituted calcium hydroxyapatite remain stable in an atmosphere of saturated water vapors, and the main losses during polarization are associated with Maxwell–Wagner losses. Analysis of the characteristics of carbonate-substituted hydroxyapatite samples obtained from a biogenic source of calcium shows their potential significance for creating biomimetic materials that imitate the structure, morphology, and anisotropy of the native solid tissue of a human tooth.

For the first time, functionally Al₂O₃ content graded Ni-Al₂O₃ composite coating has been successfully co-electrodeposited from a bath with gradually increasing stirring rate. For this, different composite coatings were electroplated in the same bath with different stirring rates to find the optimum stirring rate in which the maximum content with uniform distribution of Al₂O₃ particles in the coating can be achieved. To produce Al₂O₃ content graded Ni-Al₂O₃ composite coating, the stirring rate was continuously increased from 0 to optimum value. By increasing of Al₂O₃ particles content, the microhardness increases from interface towards the surface of the coating. The results of wear resistance measurements and potentiodynamic polarization test revealed that wear and corrosion resistances of functionally graded Ni-Al₂O₃ (FGNA) is higher than that of ordinary Ni-Al₂O₃ (ONA) composite coating. This result has been attributed to lower mechanical mismatch between coating and substrate in the functionally graded composite coating with respect to the uniformly distributed one.

The transmission sputtering of component atoms under ion bombardment of the (0001) face of a two-component VSi₂ single crystal is studied using molecular-dynamics computer simulation. The sputtering of component atoms is calculated in the case of the sputtering of virtual \({\text{VV}}_{2}^{'}\) and Si'Si₂ single crystals consisting of atoms with the same masses, and the following new effect in the selective sputtering is studied: atoms from vanadium sites are preferentially transmission sputtered in the case of the same masses and binding energies of component atoms. This effect can be called the effect of nonidentity of the component sites in the complex VSi₂ lattice (of the C40 type) with respect to the momentum propagation in collision cascades, i.e., the effect of structure in the selective sputtering of two-component single crystal targets.