Showing papers in "Ukrainian Journal of Physics in 2018"
TL;DR: In this paper, the dielectric properties and dc electrical conductivity of (PVA-PAA-PbO2) nanocomposites have been investigated in the frequency range (100 Hz-5 MHz).
Abstract: This paper aims to the preparation of novel pressure-sensitive nanocomposites with low cost, light weight, and good sensitivity. The nanocomposites of polyvinyl alcohol, polyacrylic acid, and lead oxide nanoparticles have been investigated. The dielectric properties and dc electrical conductivity of (PVA–PAA–PbO2) nanocomposites have been studied. The dielectric properties of nanocomposites were measured in the frequency range (100 Hz–5 MHz). The experimental results showed that the dielectric constant and dielectric loss of (PVA–PAA–PbO2) nanocomposites decrease, as the frequency increases, and they increase with the concentrations of PbO2 nanoparticles. The ac electrical conductivity of (PVA–PAA–PbO2) nanocomposites increases with the frequency and the concentrations of PbO2 nanoparticles. The dc electrical conductivity of (PVA–PAA–PbO2) nanocomposites also increases with the concentrations of PbO2 nanoparticles. The application of pressure-sensitive nanocomposites has been examined in the pressure interval (60–200) bar. The results showed that the electrical resistance of (PVA–PAA–PbO2) pressure-sensitive nanocomposites decreases, as the compressive stress increases. The (PVA–PAA–PbO2) nanocomposites have high sensitivity to pressure.
53 citations
TL;DR: In this paper, a generalized version of the van der Waals model with the induced surface tension was proposed to describe the nuclear and hadronic properties of a gas of hard spheres.
Abstract: A recently suggested equation of state with the induced surface tension is generalized to the case of quantum gases with mean-field interaction. The self-consistency conditions of such a model and the conditions necessary for the Third Law of thermodynamics to be satisfied are found. The quantum virial expansion of the van der Waals models of such a type is analyzed, and its virial coefficients are given. In contrast to traditional beliefs, it is shown that an inclusion of the third and higher virial coefficients of a gas of hard spheres into the interaction pressure of the van der Waals models either breaks down the Third Law of thermodynamics or does not allow one to go beyond the van der Waals approximation at low temperatures. It is demonstrated that the generalized equation of state with the induced surface tension allows one to avoid such problems and to safely go beyond the van der Waals approximation. In addition, the effective virial expansion for the quantum version of the induced surface tension equation of state is established, and all corresponding virial coefficients are found exactly. The explicit expressions for the true quantum virial coefficients of an arbitrary order of this equation of state are given in the low-density approximation. A few basic constraints on such models which are necessary to describe the nuclear and hadronic matter properties are discussed.
23 citations
TL;DR: In this paper, a nondegenerate three-level cascade laser coupled to a two-mode vacuum reservoir was studied, by employing stochastic differential equations associated with the normal ordering, and the amplification of the properties of squeezing and entanglement of the cavity light was investigated.
Abstract: We study a nondegenerate three-level cascade laser coupled to a two-mode vacuum reservoir, by employing the stochastic differential equations associated with the normal ordering The amplification of the properties of squeezing and entanglement of the cavity light is investigated We have found that there is an entanglement between the states of the light generated in the cavity, due to the strong correlation of the light emitted, when the atom decays from the top level to the bottom level via the intermediate one We have also obtained that the two cavity modes are strongly entangled, and the degree of entanglement is directly related to the two-mode squeezing
19 citations
TL;DR: In this article, the analysis of the cavity light produced by a coherently driven non-degenerate three-level laser possessing an open cavity and coupled to a two-mode vacuum reservoir is presented.
Abstract: The analysis of quantum properties of the cavity light produced by a coherently driven nondegenerate three-level laser possessing an open cavity and coupled to a two-mode vacuum reservoir is presented. The normal ordering of noise operators associated with the vacuum reservoir is considered. Applying the solutions of the equations of evolution for the expectation values of the atomic operators and the quantum Langevin equations for the cavity mode operators, the squeezing properties, entanglement amplification, and the normalized second-order correlation function of the cavity radiation are described. The three-level laser generates squeezed light under certain conditions, with maximum intracavity squeezing being 50% below the vacuum-state level. Moreover, it is found that the presence of spontaneous emission increases the quadrature squeezing and entanglement and decreses the mean photon number of the two-mode cavity radiation.
15 citations
TL;DR: In this article, the decay curves of the 4G5/2 - 6H7/2 transition exhibit a non-exponential curve fit for all concen-trations, which indicates that the energy transfer between Sm3+ ions is of dipole-dipole type.
Abstract: Room temperature visible and near infrared optical absorption and emission spectra of Sm3+-doped molybdenum gadolinium borate (MGB) glasses with molar composition 25MoO3-20Gd2O3–(55 − x)B2O3−xSm2O3 (x = 0.05, 0.1, 0.5, 1.0, 2.0 mol.%) have been analyzed. The experimental oscillator strengths of absorption bands have been used to determine the Judd–Ofelt (J–O) parameters. Fluorescence spectra were recorded by exciting the samples at 402 nm. Using the J–O parameters and luminescence data, the radiative transition probabilities (AR), branching ratios (BR), and stimulated emission cross-sections oe) are obtained. The decay curves of the 4G5/2 - 6H7/2 transition exhibit a non-exponential curve fit for all concen-trations. The concentration quenching has been attributed to the energy transfer through the cross-relaxation between Sm3+ ions. 4G5/2 level and its relative quantum efficiencies are measured. Intense reddish-orange emission corresponding to the 4G5/2−6H7/2 transition has been observed in these glasses at the 487-nm excitation, From the values of the radiative parameters, it is concluded that the 1.0-mol% Sm3+-doped MGB glass may be used as a laser active medium with the emission wavelength at 599 nm. The analysis of the non-exponential behavior of decay curves through the Inokuti–Hirayama model indicates that the energy transfer between Sm3+ ions is of dipole–dipole type. The quantum efficiency for the 4G5/2 level of MGBSm10 glass is found to be 67%. The co-related color temperature obtained from CIE (Commission International de L’Eclairage) for these glass samples is ∼1620 K for the indicated orange emission at the 402-nm excitation.
15 citations
TL;DR: In this paper, the phase equilibrium condition is shown to be strictly satisfied only in the thermodynamic limit, and the notion of melting temperature is introduced to determine the melting conditions and the melting temperature for finite systems including nanocrystals.
Abstract: The phase equilibrium condition is shown to be strictly satisfied only in the thermodynamic limit. The notion of melting temperature in the thermodynamic limit is introduced. Formulas are obtained that determine the melting conditions and the melting temperature for finite systems including nanocrystals. The validity of those formulas is confirmed, by comparing them with experimental data for organic materials in porous solids.
15 citations
TL;DR: In this paper, a unified approach to special relativity, general relativity, and quantum mechanics is presented, where each physical object from the micro-to the macroscale can be derived from an opportune diminishing of the quantum vacuum energy density.
Abstract: In Quantum Relativity, time and space are separated. Time is the numerical order of material changes, and space is the medium, in which these changes take place. Space has the origin in a three-dimensional quantum vacuum defined by fluctuations of the energy density corresponding to elementary RS (reduction state) processes of creation/annihilation of elementary quanta. Quantum Relativity provides a unifying approach to special relativity, general relativity, and quantum mechanics. Each physical object from the micro- to the macroscale can be derived from an opportune diminishing of the quantum vacuum energy density. In particular, the variable energy density of space in Quantum Relativity corresponds to the curvature of space in general relativity. In quantum theory, the behavior of each subatomic particle follows from opportune elementary RS processes of creation/annihilation of quanta guided by a quantum potential of the vacuum. Finally, the perspectives of this model regarding the view of gravity and quantum as two aspects of the same coin and the electroweak scale are analyzed.
14 citations
TL;DR: In this article, a coherently driven two-level atom with parametric amplifier and coupled to a vacuum reservoir is analyzed, and the combination of the master equation and the quantum Langevin equation is presented to study the quantum properties of light.
Abstract: The dynamics of a coherently driven two-level atom with parametric amplifier and coupled to a vacuum reservoir is analyzed. The combination of the master equation and the quantum Langevin equation is presented to study the quantum properties of light. By using these equations, we have determined the time evolution of the expectation values of the cavity mode and atomic operators. Moreover, with the aid of these results, the correlation properties of noise operators, and the large-time approximation scheme, we calculate the mean photon number, power spectrum, second-order correlation function, and quadrature variances for the cavity-mode light and fluorescence. It is found that the half-width of the power spectrum for the fluorescent light in the presence of a parametric amplifier increases, while it decreases for the cavity-mode light. Moreover, we have found the probability for the atom to be in the upper level in the presence of a parametric amplifier.
12 citations
TL;DR: In this article, the dependences of those parameters on the ratio E/N between the electric field strength and the particle concentration N in the discharge were calculated for the "air-copper vapor" system, by using the numerical simulation method.
Abstract: Parameters of the nanosecond overvoltage discharge plasma in an air gap of (1÷5) × 10−3 m between the electrodes, which contains the vapor of an electrode material (Zn, Cu, Fe) injected into plasma due to the ectonic mechanism, have been studied. The dependences of those parameters on the ratio E/N between the electric field strength E and the particle concentration N in the discharge are calculated for the “air–copper vapor” system, by using the numerical simulation method.
11 citations
TL;DR: In this paper, the authors studied the temperature and concentration dependences of the effective radii of polyvinyl alcohol (PVA) macromolecules on the basis of experimental data on the viscosity of dilute PVA solutions in dimethyl sulfoxide (DMSO) and water.
Abstract: The temperature and concentration dependences of the effective radii of polyvinyl alcohol (PVA) macromolecules have been studied on the basis of experimental data on the viscosity of dilute PVA solutions in dimethyl sulfoxide (DMSO) and water, as well as using the Malomuzh–Orlov theory of shear viscosity in polymer solutions. The temperature dependences of the effective radii of PVA macromolecules in DMSO are shown to be linear in the temperature interval 293÷353 K. At the same time, those dependences are more complicated for aqueous PVA solutions. Namely, the effective radii of macromolecules remain unchanged at relatively low temperatures and PVA concentrations, but they decrease nonlinearly at higher temperatures and concentrations. The concentration dependences of the effective radii of PVA macromolecules in both solvents are found to decrease nonlinearly in the concentration interval 0.3–3 wt.%.
11 citations
TL;DR: In this article, the impact of domain structure of ferroelectric substrate on graphene conductance has been investigated, taking into account absorbed dipole layers on the free surface of graphene and localized states on its interfaces.
Abstract: Review is devoted to the recent theoretical studies of the impact of domain structure of ferroelectric substrate on graphene conductance. An analytical description of the hysteresis memory effect in a field effect transistor based on graphene-on-ferroelectric, taking into account absorbed dipole layers on the free surface of graphene and localized states on its interfaces is considered. The aspects of the recently developed theory of p-n junctions conductivity in a graphene channel on a ferroelectric substrate, which are created by a 180-degree ferroelectric domain structure, are analyzed, and cases of different current regimes from ballistic to diffusion one are considered. The influence of size effects in such systems and the possibility of using the results for improving the characteristics of field effect transistors with a graphene channel, non-volatile ferroelectric memory cells with random access, sensors, as well as for miniaturization of various devices of functional nanoelectronics are discussed.
TL;DR: The oxygen transport is found to be mainly governed by the blood saturation with oxygen and the blood plasma viscosity, with the both parameters depending on the temperature and the acid-base balance in blood.
Abstract: The optimal temperature for the human life activity has been determined, by assuming that this parameter corresponds to the most intensive oxygen transport in arteries and the most intensive chemical reactions in the cells. The oxygen transport is found to be mainly governed by the blood saturation with oxygen and the blood plasma viscosity, with the both parameters depending on the temperature and the acid-base balance in blood. Additional parameters affecting the erythrocyte volume and, accordingly, the temperature of the most intensive oxygen transport are also taken into account. Erythrocytes are assumed to affect the shear viscosity of blood in the same way, as impurity particles change the suspension viscosity. It is shown that theoptimal temperature equals 36.6 ∘C under normal environmental conditions. The dependence of the optimal temperature for the human life activity on the acid-base index is discussed.
TL;DR: In this article, a comparison between the spectra of X-ray luminescence and photoluminescence of ZnSe among themselves in the spectral region from 400 to 1200 nm at different excitation intensities and different temperatures (8, 85, 295, and 420 K).
Abstract: The luminescence spectra of high-resistance ZnSe crystals consist of two main bands with maxima at 630 nm (1.92 eV) and 970 nm (1.28 eV). The planned comparison has been carried out between the spectra of X-ray luminescence and photoluminescence of ZnSe among themselves in the spectral region from 400 to 1200 nm at different excitation intensities and different temperatures (8, 85, 295, and 420 K). It is found that the forms of luminescence bands do not depend on the excitation intensities. The band form with a maximum at 970 nm also does not depend on the excitation type, and the band at 630 nm differs slightly under the X-ray and UV excitations. The temperature dependences of the spectral positions of bands’ maxima and their half-widths are analyzed. A conclusion is drawn that the 970-nm emission band is elementary. A short-wavelength shift of the spectral maximum of the 630-nm band with increasing the temperature makes it possible to conclude that this luminescence band is non-elementary. This correlates with the previously discovered feature of this band related to the realization of two recombination mechanisms (electron and hole) at this luminescent center.
TL;DR: In this article, the authors demonstrated the possibility to characterize the electronic excited state of a spectrally active molecule based only on the solvatochromic study of electronic absorption spectra.
Abstract: The possibility to characterize the electronic excited state of a spectrally active molecule based only on the solvatochromic study of electronic absorption spectra is demonstrated. The values of the regression coefficients given the contribution of universal interactions to the spectral shift and their theoretically established dependences on the solute molecule microscopic parameters are used. The values of the dipole moment, polarizability, and ionization potential in the ground electronic state of a spectrally active molecule are established by quantum mechanical methods. Two azo dye molecules are chosen in order to exemplify this method.
TL;DR: In this article, an external electric field was used to increase both the uniformity and deposition rate of TiO2 films, and the results showed that the films are only deposited on the external electric fields area.
Abstract: We have used an external electric field to increase both the uniformity and deposition rate of TiO2 films. The experiment is carried out by sparking-off titanium wires with a high dc voltage of 1 kV (field Eint = 10 kV/cm) and a limited current of 3 mA. The external electric fields (Eext) of 3, 6, and 9 kV/cm were applied to the sparking system for 1–5 hours. The as-deposited film morphology was characterized by scanning electron microscopy. The results clearly show that the films are only deposited on the external electric field area. Furthermore, the deposition rate of the films increased from 40.7% to 77.8% in the presence of the external electric field of 9 kV/cm. The effects of an external electric field on both the deposition rate and uniformity of films are investigated and described.
TL;DR: In this paper, the laser treatment of a composite consisting of a thin film of a metal (gold) on the surface of a semiconductor substrate [silicon (100)] has been studied.
Abstract: Peculiarities of the laser treatment of a composite consisting of a thin film of a metal (gold) on the surface of a semiconductor substrate [silicon (100)] have been studied. Micro- and nanostructurings of the metal-semiconductor composite sample have been achieved by the irradiation of its initial surface with a Ti : sapphire femtosecond laser. Laser ablation leads to the patterning of the surface of the composite with laser-induced periodic surface structures (LIPSS) and the formation of semiconductor nanohills, metal nanoparticles, and/or nanowires on the top of hills. The presence of some nanoscale surface features is confirmed by a low-frequency shift of the silicon phonon band in Raman spectra. Prepared microstructured surface barrier solar cells are characterized by means of scanning electron microscopy, optical spectroscopy, and photoelectric measurements.
TL;DR: In this article, the modified surface delta-interaction model was applied to calculate the energy levels of 16N and 16F nuclei, and good agreement between theoretical and experimental data was attained for excitation energies.
Abstract: The modified surface delta-interaction model is applied to calculate the energy levels of 16N and 16F) nuclei. The good agreement between theoretical and experimental data is attained for excitation energies. This indicates that the shell model describes properly the structure of these nuclei.
TL;DR: In this paper, the elastic-scattering angular distributions of 40Ca by different target nuclei from 32S to 208Pb were calculated within the framework of the optical model and compared with each other and with experimental data.
Abstract: To obtain alternative nuclear potentials is very important in explaining the heavy-ion reactions, as well as light-ion ones. For this purpose, a comprehensive analysis of six different proximity potentials ([1, 9–12, 15]) is performed for the first time in the present study. In order to see the availability of the potentials, the elastic-scattering angular distributions of 40Ca by different target nuclei from 32S to 208Pb are calculated within the framework of the optical model. The theoretical results are compared with each other and with experimental data. The similarities and differences of the potentials are discussed, and some alternative potentials are proposed.
TL;DR: In this paper, the dual surface plasmon resonance in Ni nanoparticles in planar nanostructures has been observed in UV-vis absorption spectra, and the dependences of the intensity, wavelength, and width of the dual SPR absorption peaks of Ni particles coupled with an Au (Ni) film on the spacer thickness have been studied in the range of 12-43 nm.
Abstract: The dual surface plasmon resonance in Ni nanoparticles in “monolayer of Ni nanoparticles/shellac film/Au (Ni) film” planar nanostructures has been observed in UV-vis absorption spectra. The dependences of the intensity, wavelength, and width of the dual SPR absorption peaks of Ni nanoparticles coupled with an Au (Ni) film on the spacer thickness have been studied in the range of spacer thicknesses of 12–43 nm. The main features of these dependences are an increase of the intensity, the blue shift, and the monotonic behavior of the widths of SPR absorption peaks at a decrease of the spacer thickness. The observed dependences have been rationalized as a result of the plasmonic coupling of the monolayer of Ni nanoparticles withthe metal film and the variation of the dielectric permittivity of the environment of Ni nanoparticles caused by the metal film presence. The stronger dependences of the SPR spectral characteristics of Ni nanoparticles have been observed in the nanostructure containing the gold film comparing to that with a nickel one. Such effect is due to the stronger coupling of Ni nanoparticles with an Au film, and the stronger influence of an Au film on the permittivity of the environment of Ni nanoparticles.
TL;DR: In this article, the decrease of the antitumor efficiency of the hybrid ternary nanosystem polymer/AgNPs/cisplatin in comparison with the polymer-cis-Pt system is discussed.
Abstract: Hybrid nanosystems consisting of star-like copolymer Dextran-graft-Polyacrylamide in the anionic form (D-g-PAA(PE)), silver nanoparticles (AgNPs), and cisplatin (cis-Pt) have been synthesized in water and characterized by TEM, DLS, FTIR, and UV-Vis spectroscopies. It is shown that cis-Pt forms a complex with carboxylate groups of the polymer. For the ternary system Polymer/AgNPs/cis-Pt, a change in the hydrophilic-hydrophobic balance of a polymer molecule (due to the complexation with cis-Pt) and the aggregation of macromolecules, as well as to some agglomeration AgNPs, are revealed. The decrease of the antitumor efficiency of the hybrid ternary nanosystem Polymer/AgNPs/cis-Pt in comparison with the Polymer/cis-Pt system is discussed.
TL;DR: In this article, the authors considered the self-diffusion coefficient in low-molecular fluids as the sum of two components: one of them is associated with the transfer of molecules by hydrodynamic vortex modes, and the other is generated by the circulatory motion of local molecular groups.
Abstract: The nature of the self-diffusion in low-molecular fluids is discussed. The particular attention is paid to atomic fluids (such as argon), liquid metals, and associated fluids (such as water). The self-diffusion coefficient in the fluids of all indicated types is considered to be the sum of two components: one of them is associated with the transfer of molecules by hydrodynamic vortex modes, and the other is generated by the circulatory motion of local molecular groups. The both components have a collective nature, they are genetically related to each other and differ only by their scales: the former is mesoscopic, the latter is nanoscopic. Manifestations of the collective vortical transport of molecules as specific features in the time dependence of the root-mean-square displacement of molecules are discussed. Sound arguments are proposed concerning the inadequacy of the activation mechanism of thermal molecular motion in low-molecular liquids. The immanent contradiction of exponential temperature dependences for the viscosity and self-diffusion coefficients is proved. In all cases, the preference is given to qualitative arguments.
TL;DR: In this paper, the correlation between vibrational and electron excitation modes in the energy spectra of single-layer graphene and crystalline graphite, as well as the dispersion dependences of those modes, has been studied.
Abstract: The correlation between the vibrational and electron excitation modes in the energy spectra of single-layer graphene and crystalline graphite, as well as the dispersion dependences of those modes, has been studied. The methods of the theory of projective representations of the point and spatial symmetry groups are used for the first time in order to interpret those correlations. The correlations of vibrational and electron excitation spectra and the compatibility conditions for irreducible projective representations in the descriptions of quantum states of graphene and crystalline graphite at various points of their Brillouin zones are determined. For the projective representations of all projective classes belonging to the hexagonal system, standard factor-systems are constructed for the first time. In particular, the factor-systems for electron states are first determined. The results obtained are used to calculate, also for the first time, the correct spinor multiplication tables, i.e. the multiplication tables for elements in double symmetry groups. The developed method is applied to classify all high-symmetry points in the Brillouin zones of single-layer graphene and crystalline graphite with respect to the symmetry type of vibrational excitations.
TL;DR: In this paper, the authors studied the process of magnetogenesis in the single-field inflation model, whose parameters are chosen in accordance with the recent observations by the Planck collaboration, and found that the magnetic fields generated without back-reaction problem cannot exceed ∼10−20G at the present epoch, and their spectrum has a blue tilt.
Abstract: We study the process of inflationary magnetogenesis in the natural single-field inflation model, whose parameters are chosen in accordance with the recent observations by the Planck collaboration [1]. The conformal invariance of the Maxwell action is broken by a kinetic coupling with the inflaton field by means of the coupling function as a power of the scale factor, I(ф) ∝ aa, and a < 0 is used in order to avoid the strong coupling problem. For such a, the electric component of the energy density dominates over the magnetic one and, for a <- −2.2, it causes a strong back-reaction, which can spoil inflation and terminate the enhancement of the magnetic field. It is found that the magnetic fields generated without back-reaction problem cannot exceed ∼10−20G at the present epoch, and their spectrum has a blue tilt.
TL;DR: In this article, the specific features of clustering in aqueous solutions of monohydric alcohols with concentrations higher than that at the peculiar point are discussed and the solution clustering degree is determined as a function of the solution concentration and the temperature.
Abstract: The specific features of clustering in the aqueous solutions of monohydric alcohols with concentrations higher than that at the peculiar point are discussed. Clustering is a result of the formation of hydrogen bonds between water and alcohol molecules, the energy of which some-what exceeds the energy of hydrogen bonds in the water-water and alcohol-alcohol molecular pairs. Elementary clusters are assumed to be formed, whose composition is fixed at the solution concentrations lower than that at the peculiar point and changes according to a certain law at higher concentrations. The solution clustering degree was determined as a function of the solution concentration and the temperature.
TL;DR: In this article, the potential energy in pairs of the type hydroxyl solvent-ylid is estimated in the frame of the statistical cell model of ternary solutions, from the viewpoint of interactions in the first ylid solvation shell, the statistical average weight of the active solvent differs from its molar fraction in the binary solvent.
Abstract: The molecule of (4 ′-phenyl)-1,2,4-triazol-1-ium-phenacylid (PTPhY) is studied in two types of ternary solutions. In the first category, the binary solvent contains two hydroxyl miscible liquids, and the second one contains one protic and one non-protic solvents. The potential energy in pairs of the type hydroxyl solvent-ylid is estimated in the frame of the statistical cell model of ternary solutions. From the viewpoint of interactions in the first ylid solvation shell, the statistical average weight of the active solvent differs from its molar fraction in the binary solvent.
TL;DR: In this paper, a transparent superhydrophobic nanocoating with high water contact angle (>150∘ ) was successfully prepared by a simple dip coating method, which was prepared by the dissolution of polystyrene (PS) and poly(methyl methacrylate) (PMMA) in toluene.
Abstract: A transparent superhydrophobic nanocoating with high water contact angle (>150∘ ) was successfully prepared by a simple dip coating method. The coating solutions were prepared by the dissolution of polystyrene (PS) and poly(methyl methacrylate) (PMMA) in toluene. Fumed silica (SiO2) was then added to increase the roughness of the coating. The annealing treatment conditions were investigated to optimize the water contact angle. The heat treatment conditions and other factors were studied systematically to optimize the transmission and the contact angle of water on the films. The results have shown that the films increase with the annealing temperature. The superhydrophobicity of films is observed only in PS-consisted films after the annealing at 200 ∘C. The superhydrophobic/superhydrophilic transformation was achieved at the annealing temperature higher than 200 ∘C due to the decay of the polymer into hydrophilic monomers.
TL;DR: The analysis of the frequency distribution of the amplification of optical radiation due to the Raman effect (Raman gain profile) in single-mode fibers based on silica glass has been carried out in the region of Stokes frequency shifts from 0 to 1400 cm−1.
Abstract: The spectroscopic analysis of the frequency distribution of the amplification of optical radiation due to the Raman effect (Raman gain profile) in single-mode fibers based on silica glass has been carried out in the region of Stokes frequency shifts from 0 to 1400 cm−1 The Raman gain profiles are determined from the experimental spectra of spontaneous scattering for widespread fibers, namely for pure SiO2, GeO2, P2O5, and TiO2 doped fibers The analytic expressions of the Raman gain profiles are given They are obtained, by using the Gaussian decomposition by means of 11–12 modes, and the experimental profile is approximated with an accuracy of not less than 03% The decomposition results are analyzed in terms of the fundamental oscillatory dynamics of molecular nanocomplexes in amorphous glass, as well as in the application aspect of the modeling of photonics devices Examples of the proposed method applications are presented for the analysis of noise parameters of the fiber Raman amplifiers and for the generation bandwidth in fiber Raman lasers
TL;DR: In this article, a mechanism describing the formation of a corrugated boundary of the mesomorphic phase is proposed, where the corrugation period and depth are evaluated, and the dissipative Rayleigh-Taylor instability is considered.
Abstract: The dissipative Rayleigh–Taylor instability, which can arise at the interface between biomaterials under the action of high-frequency currents, has been considered. A mechanism describing the formation of a corrugated boundary of the mesomorphic phase is proposed. The corrugation period and depth are evaluated.
TL;DR: In this article, an approximation for cluster integrals of an arbitrary high order has been proposed for the well-known lattice-gas model with an arbitrary geometry and dimensions, based on the recently obtained accurate relations for the convergence radius of the virial power series in the activity parameter for the pressure and density.
Abstract: An approximation for cluster integrals of an arbitrary high order has been proposed for the well-known lattice-gas model with an arbitrary geometry and dimensions. The approximation is based on the recently obtained accurate relations for the convergence radius of the virial power series in the activity parameter for the pressure and density. As compared to the previous studies of the symmetric virial expansions for the gaseous and condensed states of a lattice gas, the proposed approximation substantially approaches the pressure values at the saturation and boiling points. For the Lee–Yang lattice-gas model, the approximation considerably improves the convergence to the known exact solution.