Izvestiya of Saratov University.
ISSN 1817-3020 (Print)
ISSN 2542-193X (Online)


Физика

Production of Tungsten Spherical Microparticles in Ultrasonic Field at Presence an Activator

It has been shown by experiments, that spherical tungsten microparticlein etching solution under the ultrasonic exposure is possible. The process of obtaining consists of two stages. At the first stage, by centrifuging a suspension of tungsten powder with an average particle size of 0.5 microns in the activator – etching from a water solution of potassium hydroxide and potassium ferricyanide, obtained tungsten thin plate of any shape, thickness 1–3 micrometers.

Morphology of Gas Sensitive Tin Dioxide Thin Films Operating at Room Temperature

Tin dioxide thin films sensing ethanol vapors above the room temperature (38° C) were deposited by RF magnetron sputtering onto silicon substrates. Microstructure measurements using scanning electron microscopy and atomic force microscopy demonstrate that samples consist of grains shaped rods with nanometer diameters which are oriented normally to the substrate surface. There are pores between the grains penetrating the entire thickness of the films.

Morphological Changes in Transplanted Sarcoma S45 at Photodynamic Therapy Using Nanocomposites Based on Gold Nanorods

Photodynamic therapy (PDT) of cancer is an advanced application of gold nanostructures. The purpose of the research is to study the morphological changes in the transplanted sarcoma S45 at PDT using nanocomposites based on gold nanorods (GNRs). GNRs synthesized with the germ method and covered by a silicon coating, functionalized by hematoporphyrin, were intratumorally injected in rats with transplanted sarcoma S45. The tumor was irradiated by He-Ne laser with a wavelength of 632.8 nm.

Calculation of Scale Factors for Quantum-mechanical Force Fields

A computer-assisted method for the calculation of scaling factors for refining the quantum-mechanical force fields of polyatomic molecules by the Pulay technique is suggested. The method is an iteration procedure and does not involve the calculation of derivatives of the frequencies of vibrations with respect to the scaling factors.

IR Spectra of Salol and theirs Interpretation by Molecular Modeling

IR spectra of salol have been measured at stable and metastable phases at temperature range from 11 to 298 K. IR spectra are different. We suggest that conformational mobility of salol and influence of H-bonding are responsible for the differences.

Low-density Approximation in the Theory of Creation the Electron-positron Plasma from Vacuum in Strong Laser Fields

Kinetic description of the vacuum creation of the electron-positron plasma under action of the strong electromagnetic fields is considered in two simplest approximations. The results are compared with the numerical solution of the relevant kinetic equation. It allows to select the regions of effectiveness of the introduced methods and to analyse some features of the obtained analytical solutions.

The Influence of Monogaloidosubstitution on the Structure and Dynamics of Sixmember Cyclic Compounds

The structure and vibrational states of monosubstituted cyclic compounds (monogaloidosubstituted of benzene, benzoquinone, gammapyrone and tiopiron) by density functional DFT / b3LYP 6-311G ** and 6-311+** are simulated. Vibrational states are interpreted.

Recovery of Models of Time-delay Systems from Short Experimental Time Series

Time-delay systems reconstructed from short and noisy time series is conducted by the specialized method based on utilizing of driven system with the structure similar to the structure of the studied object. To show the efficiency of this approach, parameters were reconstructed for radiophysical chaotic generator and for the model of biological system.

Application of Thin Film Structures Based on Amorphous Silicon for pH Measurements in Solutions

Formation possibility of pH-sensor based on amorphous silicon thin films is shown. The principle of sensor operation is similar to the ionselective field effect transistor. Change of the investigated solution pH leads to change of depletion width and conductivity of amorphous silicon thin film structure.

Calculation of Field Amplitude Distribution of Ultrasonic Wave Beam in Moving Media

The results of acoustical (ultrasonical) wave beam amplitude distribution modeling in free space and in application of moving media are presented. The propagation of ultrasonical wave has been considered in x-y coordinate plane for infinitive plate radiator restricted on x – axis. The shift of ultrasonical beam field for different distributions of moving media velocity projections in the plane of wave propagation is considered.

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