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This article considers problems of construction and theoretical substantiation of computational algorithms for analyzing generalized V. M. Glushkov integral models based on the V. K. Dzyadyk approximation method.

On the basis of V. Dzyadyk’s approximation method, we consider the problems of construction and theoretical substantiation of high-precision numerical-analytic algorithms for the piecewise polynomial approximation of the solutions of problems with pulsed action.

The authors propose, theoretically substantiate, and programmatically implement high-precision numerical-analytical algorithms for approximation of problems solutions in inhomogeneous media on the basis of linear polynomial operators.

The possibility of modifying the photoluminescence properties of porous silicon by irradiation with low doses of γ photons from a 226Ra radioisotope source and bremsstrahlung is demonstrated. The position of the longest photoluminescence wavelength tends to shift to the short-wavelength region of the spectrum. The emission efficiency increases upon irradiation of both the substrate and the layer formed.

The effect of low exposure doses (5–40 kR) of gamma radiation on the electrical properties of structures based on a mesoporous silicon (SiMP) layer is investigated. It is demonstrated that the conductivity of the SiMP layer increases, the Fermi level shifts, and the trap density changes in gamma-irradiated Al/SiMP/p-Si/Al structures. Long-term stable switched-state memory in the region of the I–V curve hysteresis is revealed. This effect is controlled by the irradiation dose.

The work is devoted to the finding of the formula for calculating the drying time of a vertical cylindrical tank. The structure, applications and main types of this vertical tank and its advantages in comparison to the horizontal tank are described. The figuring out of the formula is based on the method of solving a differential equation of first order for pump capacity (performance), a time-dependent operation of the pump and liquid volume, depending on the height of the decreasing liquid.

The paper presents the method of tunneling microscopy study of mass transfer in the structure containing nanometer layer AgI. The possibility of using of interface Ag-AgI-insulator-metal as a resistive switching memory with charge ∼5 pC and multiplicity of resistance ∼20 is shown.

Electrical and photoelectric properties of porous silicon with introduced silver nanoparticles have been studied. It is shown that in the “dark–light–dark” operation mode, an abrupt jump of the dark current is observed upon illumination (with light spectrally close to sunlight), which is three to five times the initial dark current and the photocurrent. The voltages at which these abrupt changes in current are observed correspond to the range of existence of traps formed when the starting mesoporous silicon is obtained. It was found that the increased value of the dark current exhibits a long-term memory effect. The “current jump” can be attributed to the maximum capture of the generated photocarriers by traps, followed by their release in an electric field after the illumination.

A comparative study of the optical and morphological properties of different modifications of silicon and their dissolution upon interaction with distilled water and a biologically active medium is carried out. For the biologically active medium, nonpathogenic baker’s yeast (Saccharomycetes cereviseae) is chosen. It is shown that water and the biologically active medium interact with the surface of the materials and, thus, change the surface morphology and produce a modified layer. The strengths of the effect upon nanoparticles, nanoparticle-based structures (porous silicon), and single-crystal silicon doped with different types of impurities to different levels are different.

It was shown that the complex research of iron nanoparticles properties by different methods, supplemented each other, permit to receive the data about the interior sizes of nanoparticles, a number of physical properties of particles, their dependence on frequency and changes produced by various influences. It was found that the conductivity of nanoparticles changed under the square depen-dence σ = σoω2

The photoelectric and photovoltaic properties of structures based on mesoporous silicon passivated with iron (SiMP:Fe) are studied. It is shown that these properties ambiguously depend on the iron concentration. In the case of a sample with space-charge-limited currents (SCLCs), the charge-transport mechanism in the Al-SiMP:Fe-p-Si-Al heterostructure changes under illumination from the SCLC type to the barrier type. Passivation with 0.1–0.2 at % iron stabilizes not only the electrical, but also the photoelectric and photovoltaic properties of the structures. A further increase in the Fe concentration gives rise to new traps caused by the appearance of iron and silicon oxides, which leads to instability of the properties. The structures exhibit high sensitivity under low-level illumination. The open-circuit voltage is 16 mV under AM-1 irradiation (∼2 mW/cm2).

The structure and elemental composition of graphite inclusions uncovered on high-strength cast iron by etching are studied. The chemical composition at various points and regions of graphite inclusions is determined. It is shown that the globular graphite is a unique lamellar-spiral system of micro- and nanoformations.

Annotation An experimental and theoretical research work on the corrosion processes of heat exchanger channels made from different aluminum alloys in an ethylene glycol antifreeze environment conducted by the authors is described in the article. The hydrodynamic simulation of the flow in the paths was performed. Significant effects of the aeration of the power fluid, the possibility of electrochemical corrosion are proved. The comparative of anti-corrosion property of different aluminum alloys is shown when operating in a wide range of power fluid velocities and temperatures.

The current-voltage and capacitance-voltage characteristics of structures based on mesoporous silicon, obtained by electroless etching with passivation by iron, (SiMP:Fe) are investigated. It is shown that the conductivity and barriers in Al-SiMP:Fe-p-Si-Al heterostructures ambiguously depend on the Fe concentration. Passivation by iron changes not only the conductivity of the SiMP:Fe layer but also the character of carrier transport at low frequencies. At an iron concentration of ∼1 at % tunneling transport through barriers becomes dominant in comparison with jumps over dangling bonds. Passivation of the SiMP layer by iron stabilizes the SiMP electrical properties (which is confirmed by the values of the trap concentrations estimated from the current-voltage characteristic) of structures subjected to long-term storage. This is likely to be related to the interaction between iron ions and the silicon surface with the formation of oxides.

The possibilities of modifying the IR spectra of porous silicon under irradiation by low doses of gamma — quanta of radioisotope source of 226Ra and bremsstrahlung radiation are investigated.

The electrical and photoelectric properties of nanostructures with porous silicon layers obtained by electroless etching of silicon have been investigated. It is found that the photoelectric and photovoltaic properties of these structures depend on their morphology and are determined by not only the properties of the modified layer, but also the presence of possible barriers in the layered porous silicon. The ratio of the photoconductivity to the dark conductivity reached 102−5 × 102. An open-circuit voltage V oc was detected that amounted to ∼250 mV at an incident light power close to AM-1 (∼100 mW/cm2). In this case, the density of short-circuit current I sc was about 20 μA/cm2.

The possibility of multiparametric determination of properties of structures from the data on the dependence of reflectances Rp and Rs for polarized radiation and ratio Rp/Rs on the angle of incidence θ and from the angular dependence 1/Rp(ΔR/Δθ) is investigated. The results of natural and computer experiments revealed a high sensitivity of the angular dependence Rp(θ) of the reflectance to the values of optical constants and thickness of layered structures. Quantitative results of multiparametric measurements are verified by the independent method of spectral ellipsometry. The possibility of multiparametric determination of the properties and thickness of nanometer dielectric, metallic, and semiconducting layers on various substrates and the properties of substrates in such structures is established.

The electron-transport processes in structures with oxidized porous silicon (OPS) are investigated during adsorption and desorption of polar molecules from atmosphere when the air pressure varies. It is shown that the cause of the existence of the open-circuit voltage in Pd-OPS-p+-Si-Al structures in the initial state is the surface-charge change on the Pd-OPS interface due to the polar-molecule adsorption from atmospheric air. The desorption of atmospheric-air molecules leads to a change in the current-voltage characteristics of structures, growth of the metal-OPS barrier in samples with the Schottky barrier, and initiation of current instabilities. The nanocrystalline nature of OPS manifests itself in the charge-carrier localization in quantum dots (QDs) during desorption in samples with space-charge-limited currents.

The effect of illumination and adsorption of polar molecules on the properties of structures based on oxidized porous silicon has been investigated. The specific features of these structures are fluctuations and a change in the sign of open-circuit voltage under the influence of long-term photoexcitation, time-related instabilities of the current in media with a high content of hydrogen sulfide, long periods of photocurrent decay after switching off the illumination, and the occurrence of negative photoconductivity in structures with space-charge-limited currents. The results obtained are explained by the presence of multiply charged traps of different types in oxidized porous silicon, their charge exchange, and the tunneling of charge carriers between silicon nanocrystallites.

The results of numerical simulation of a nanodimensional film-transition layer-absorbing substrate structure are presented. It is found that the transition layer affects the accuracy of determining the refractive index and thickness of the nanodimensional coating. It is shown that the introduction of the effective values of the refractive index and absorption coefficient of the substrate improves the accuracy of ellipsometric measurements of the nanodimensional film parameters. Physical (full-scale) and numerical experiments demonstrate that, when the thickness and refractive index of a nanodimensional film on a substrate with an unknown transition layer comparable in thickness with the film are measured, it is appropriate to replace the substrate-transition layer structure by a substrate with effective optical parameters. It is found that a change in the thickness of the transition layer does not noticeably affect the accuracy of determining the thickness and refractive index of the film deposited when the effective values of the refractive index and absorption coefficient of the substrate are used.

A noncontact method for the express-testing of the relative deformation of lattice parameter (Δa/a ) of semiinsulating GaAs has been developed. This method is based on measuring the reflected radiation in band-to-band regions L3v - L1c and X5v - X3c. The suggested method ensures a resolution of 4 × 10-5 in determining (Δa/a ) and has a measurement accuracy of about 0.5%.

The effect of adsorption of hydrogen-sulfide and acetone polar molecules on current-voltage characteristics and time dependences of the current was studied for the 〈Pd-por-Si(O)-p+-Si-Al〉 structures based on oxidized porous silicon. Structures of two types were obtained—those with a Schottky barrier and those with space-charge-limited currents. The presence of a positive space charge was found near the palladium electrode; this charge defined the current-voltage characteristics in the region of V

In situ measurement of the formation process of low-dimensional porous silicon (PS) structures was developed. The measurements are based on the analysis of polyharmonic time dependence of the reflected radiation. The results show high sensitivity to H 2 S in PS based structures with catalytic (Pd, Ni) and ohmic (Al) electrodes. In the best samples the appearance of three molecules H 2 S on 10 9 molecules N 2 increased the electrical current value by a factor of 2–3. The structures selectively measure H 2 S concentration from 0.02 to 1000 ppm. It was found that unusually high reversible and nonreversible optical properties change because of the influence of gas solvents and alcohol. The exposure of PS layers to ethyalcohol vapor changes the color of PS from bright blue to crimson and the refraction coefficient in the IR region changes up to 0.06.

The kinetics of nitridization of a-Si:H layers, the properties of the structures that are formed and a-Si:H in them have been investigated. The changes occurring in the resistance of the a-Si:H layers in the course of nitridization are described in terms of the competition between doping, transport, and change in the thickness of the remaining a-Si:H layer. The experimental data on the band spectrum of superlattices with a-Si:H and a-SiNx:H layer thicknesses ∼35 A and ∼5 A, respectively, are in agreement with calculations in a model of interacting quantum wells with m*=(0.36±0.1)m0. Comparison of the properties of superlattices obtained by deposition of successive layers and nitridization of the a-Si:H layers showed that the latter can have a higher “structural perfection.”

In the present study a novel approach to caries management based on the application of nanoparticles of different nature to increase the mineral phase of demineralized dentin has been developed. Silver nanoparticles have been tested as a material for dentine matrix infiltration. Research findings clearly show that collagen fibers of demineralized dentine could be considered as a scaffold for mineral component delivery and the place where mineral growth can occur. Keywords : dental research, demineralized dentine, dentin collagen fibers, nanotechnologies, silver nanoparticles, nanoparticle infiltration, scanning electron microscopy 1. INTRODUCTION The first stage of caries developing is characterized by hard tooth tissue demineralization. A series of methods are being developed to manage the caries process; one of the most popular is the application of remineralizing therapy along with demineralized dentine collagen matrix protection. In clinical practice a variety of strategies of dentine and enamel remineralization based on the application of bioactive glasses, calcium hydroxiapatite, fluoride delivering materials, artificial saliva and others are in common use

In the present study nanoparticulate silver filler influence on adhesive system mechanical properties has been researched. In the course of laboratory experiments it has been shown that adhesive system mechanical properties are changing in a different manner as soon as silver percentage in adhesive system is increasing. It has been established that 0,5 –1% silver nanoparticle embedding into adhesive system that is enough to make the material X-Ray-sensitive holds its mechanical properties close to the optimum. Thus, the mechanical properties are enhancing in comparison with those of adhesive system without silver nanoparticles. Research findings point to the opportunity to use nanoparticulate silver as a filler while producing X-ray adhesive systems.

Crystal formations were observed on the surface of etched dentine after it had been exposed to 95% ethanol in solution for 30 days at room temperature. 3D visualization of surface formations was carried out using a scanning electron microscope and Alicona 3D MeX software (Alicona GmbH). Metric characteristics of the mentioned above structures were evaluated and the nature of possible errors on the steps of model design was studied. It was shown that the shape of crystal models were likely to be approximated by ellipsoid segments.

In the present study a new adhesive system with embedded PVP-stabilized nano-particulate silver markers has been designed. Nanosized silver was used as a radio-opaque contrast material in SEM examination of adhesive system in dentine. It was studied the impact of nano-particulate silver fillers on rheological properties of adhesive system and its penetration in dentine volume. A SEM comparative evaluation of resin replicas produced using adhesive system with embedded silver nanoparticles and that without ones was carried out. It was shown that embedding of silver nanoparticles into adhesive system did not make its penetration worse. It was established that embedding of nanosized silver changed adhesive system morphology. The methodology that allows visualizing interfaces and intermediate layers between dentine, adhesive system and restorative material using silver nano-particulate markers was developed and approved. Silver nanoparticles were used to compare the objective depth of penetration of adhesive systems of different generations in root dentine with differently oriented dentinal tubules, bonding resin delivery and gravity.

Laboratory experiments conducted in Saratov State University in the first half of 2012 revealed crystal formations on the surface of etched dentine after it had been exposed to 95% ethanol in solution for 30 days at room temperature. It was discovered that the structures observed were calcium-phosphate crystals. The nature of crystal formation on rough dentine surface was described based on substance diffusion in solution, which resulted in dentine becoming spatially inhomogeneous over time. The crystal formation was established to be determined by the limited ion redistribution in dentine material.

Memristor structures based on tunnel-thin organic dielectric and porous silicon layers are investigated.

Electrodynamic properties' investigation of chemisorption materials ≪POLYCON K≫ with introduced iron and nickel nanoparticles are discussed.

Arc plasma synthesis of iron nanoparticles: morphological, dielectric and magnetic characterization are discussed.

The current-voltage and the current-capacitance characteristics of structures on the basis of mesoporous silicon received by nonelectrolitic method of etching at passivation by iron (SiMP:Fe) are investigated. It is shown, that in heterostructures Al-SiMP:Fe-pSi-Al conductivity and barriers depend on Fe concentration no monotonic.

The effect of biologically active environments and water on various modifications of silicon are investigated.

Nickel nanoparticles influence on the electrical properties of porous silicon obtained by the no-current electroless etching are investigated.

The influence of NiSO 4 saturation on the electrophysical mesoporous silicon layers obtained by electrochemical method are investigated.

In this study the methodology of biological sample preparation for dental research using SEM/EDX has been elaborated. (1)The original cutting equipment supplied with 3D user-controlled sample fixation and an adjustable cooling system has been designed and evaluated. (2) A new approach to the root dentine drying procedure has been developed to preserve structure peculiarities of root dentine. (3) A novel adhesive system with embedded X-Ray nanoparticulate markers has been designed. (4)The technique allowing for visualization of bonding resins, interfaces and intermediate layers between tooth hard tissues and restorative materials of endodontically treated teeth using the X-ray nano-particulate markers has been developed and approved. These methods and approaches were used to compare the objective depth of penetration of adhesive systems of different generations in root dentine. It has been shown that the depth of penetration in dentine is less for adhesive systems of generation VI in comparison with bonding resins of generation V, which is in agreement with theoretical evidence. The depth of penetration depends on the correlation between the direction of dentinal tubules, bonding resin delivery and gravity.

We describe a numerical-analytical algorithm to solve the boundary-value problem for the integrodifferential equation of particle transport in a plane homogeneous medium. The general scheme of approximate solution of this problem is based on its reduction to the solution of some integral equation by summator operators of function approximation theory. Solvability conditions are established for the approximate equations and the algorithm errors are estimated. Working formulas are presented for the algorithm implemented in the form of a computer program. The summator operators in this algorithm are the algebraic interpolation operators with nodes at the extremal points of Chebyshev polynomials of first kind.

This article deals with investigation of nanostructures properties' synthesized by no-current modification of monocrystal silicon.

This article deals with investigation of nanolayers' properties generated on Si surface in H 2 O

The possibilities of creating sensors on the basis of silicon structures with classical and quantum-dimensional effects have been researched theoretically and experimentally. The technology of forming qnantuln-well and wire structures of porous and amorphous silicon and their modifications by multiparameter monitoring in situ has been studied. H 2 S sensor samples, developed on this basis, have a high sensitivity (on the level 10-20 ppb), low operating voltage (1-1.5 V), low power consumption (not more than 10 -8 -10 -6 W) and relative selectivity to hydrocarbons, CO and CO 2 . The most sensitive to H 2 S ate structures having p = 0.03 Ω cm, oxidized porous silicon layer thicknesses of 6-10 μcm, porosity of 0.75-0.8 and Pd layer thicknesses of 50-60 nm. The obtained results verify the principle possibilities in solving all growing contradictions between information processing and its reception by using low-dimensional structures.

In sectional operation the basic attention is given to clearing up of dependences between an acting voltage and change of properties of an aggregate in field before failure of system, in which the realization both continuous, and jump changes of properties is possible. This field is of interest for those applications in an electronics, in which the hysteresis of properties and storage of action is not necessary.