# Search articles

## Plasmonic Rectification of Terahertz Radiation in a Grating-gated Graphene

The theory of the plasmonic rectification of terahertz radiation in a homogeneous graphene gated by a metal grating with an asymmetric unit cell is developed.

## 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.

## Phase Dynamics Modeling Technique for Estimation of Delayed Couplings between Nonlinear Oscillators Accounting for Influence of Amplitudes

An established interval estimator of a time delay in coupling between oscillators, which is based on empirical modeling of phase dynamics and maximum likelihood formalism, is shown to give sometimes erroneous conclusions about the value of the time delay. It occurs when the dynamics of amplitudes affects phases, which is typical of nonlinear oscillatory systems under the influence of strong noises or in chaotic regimes. We suggest an empirical criterion to diagnose such situations and a modified estimator of time delay which allows one to avoid erroneous conclusions.

## 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.

## Chaos in the System of Three Coupled Rotators: from Anosov Dynamics to Hyperbolic Attractor

The work presents an example of a system with chaotic dynamics built of three rotators by modifying a conservative system with hyperbolic Anosov dynamics. Results of a computational study of chaotic dynamics are considered (portraits of attractors, time dependences of the variables, Lyapunov exponents, and spectra) and good correspondence is observed between the dynamics on the attractor of the proposed system with the reduced model, characterized by the Anosov dynamics at appropriately defined energy.

## Nonequilibrium the Microwave Plasma of Low Pressure in Scientific Researches and Development Micro and Nanoelectronics

Advantages and benefits realization use of nanotechnology of high ionized low-energy microwave plasma of low pressure are described. It presents the fact that one installation on the basis of microwave plasma can replace up 4 to 5 installations with usual high-frequency excitation of the gas discharge.

## Model of Cardiovascular System Autonomic Regulation with a Circuit of Baroreflectory Control of Mean Arterial Pressure in the Form of Delayed-Feedback Oscillator

A mathematical model of human cardiovascular system autonomic regulation is proposed having the form of differential equation set. Some equations of the model contain terms with time delay. The spectral analysis shows that the proposed model exhibits better qualitative and quantitative coincidence with experimental data than the known models.

## Statistic Characteristics of Akulinichev’s Map

Perron – Frobenius equations for Akulinichev’s map are formulated. The autocorrelation function of the map orbits is analytically calculated.

## Model Potentials of Intermolecular Interaction Pyridine, Skatole and Pyrrole with Water

The calculations of the lengths of hydrogen bridge and frequencies of vibrations of bonds in the formation of hydrogen bonds skatole, pyridine and pyrrole with the water molecules in the approximation of B3LYP/6-31G(d,p). The calculations of model potentials of intermolecular interaction of the molecules on the basis of formulas Lennard–Jones and Morse, allowed to account for changes in the length of hydrogen bonds depending on the number of water molecules participating in the formation of complexes.

## Influence of 40%-glucose Solution on a Human Corneal Structure

Effective treatment of the patients with postoperative corneal edema is one of the actual problems in ophthalmology. In this paper results of complex monitoring of influence of 40%-glucose solution on the state of both normal and edematous cornea after a cataract phacoemulsification on the base of date of confocal microscopy and optical coherence tomography have been presented. It has been shown that the glucose solution induces a short-term swelling of the healthy cornea and dehydration of the edematous one, as well as optical clearing of the tissue in the both cases.

## Optimization of Phacoemulsification in Different Forms of the Cataract in the Patients with Diabetes Mellitus

In this work, human lens pathology in different forms of the cataract was studied. Two hundred twenty patients with a cataract (220 eyes) were included in the study. Morphological, immunohystological and immunocytochemical investigations of both lens capsule and substance with antibodies to α- (α-А and α-В), β-, and γ- crystallines were carried out. Diabetic patients revealed a more pronounced expression of α- and β-B crystallin compared with a group of patients with age-related cataracts. Correlation between composition of the crystallines in a lens and its density was demonstrated.

## Ecological Diagnostics of the Safety of Premises

A study was made of the radiation background of premises of economic and household purposes under various conditions. According to the data obtained, a vertical distribution of the exposure rate of premises was revealed; the influence of external factors on its value was established. Dependences were obtained and features of radiation background changes in the rooms under study were revealed. The contribution of finishing materials to the increase in the exposure rate was found.

## Constructive Interference of Optical Solitons in Dispersion Oscillating Fiber

In this article the results of numerical modeling of soliton’s collision in dispersion oscillating fiber are presented. Nonlinear Schroedinger equation for modelling was used. Different propagation regimes of the couple of solitons are considered. One of these results is merging of two solitons into high-intensity pulse.

## Thermostable Tunable YIG Oscillator

In the paper the original construction of thermostable electrically tunable microwave YIG oscillator with planar resonator in feedback loop is proposed. PCB of oscillator with tunable coil and thermocompensated system is located inside the screen of the portable magnetic system. Temperature drift YIG resonator frequency compensated temperature demagnetization of permanent magnets.

## Numerical Simulation of Vibronic Spectra for Polyatomic Molecules

Algorithms for vibrational analysis of the excited electronic states of molecules and calculations of molecular structure at electronic excitation are described. Algorithms are realized in the form of special programs. Basic data of programs are described. All initial data for this complex are formed on the basis of the molecular dynamics and quantum models. Solution algorithms of the inverse vibronic task allowing to estimate frequencies of normal modes, force fields in the raised electronic conditions and to calculate molecular geometry changes at electronic excitation are developed.

## Temperature Effects in Vibronic Intensity of Absorption and Resonance Fluorescence Spectra

Algorithms and program for calculation of the vibronic absorption and fluorescence molecular spectra are described taking into account the dependence of intensities on temperature. The algorithms are based on the construction of molecule’s quantum models in ground and excited electronic states with application of ab initio and density functional methods. The theoretic study of excited electronic states for polyatomic molecules, prediction of electronic absorption and fluorescence spectra of polyatomic molecules, the temperature dependence of intensities are described.

## 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.

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