Thermal conductivity of two binary mixtures of gases of equal molecular weight

The paper reports new measurements of the thermal conductivity of two binary mixtures at a nominal temperature of 27.5°C but over a pressure range. The two systems, N₂-CO (three compositions up to 12MPa) and N₂O-CO₂ (four mixtures up to 4.2 MPa) have been chosen because they consist of molecules of similar structure and equal molecular weight (28.01 and 44.01, respectively). Moreover, the zero-density viscosity is identical within each mixture.The results have been extrapolated and fitted to equations in the usual way. The zero-density thermal conductivity in each system varies systematically with composition and differs by about 4% for the pure components in each case. This is a measure of the effect of the internal degrees of freedom on thermal conductivity.In the absence of a reliable theory, it is shown that the equations of kinetic theory can be used to represent the composition-dependence of zero-density thermal conductivity with a judicious choice of two quantities which cannot be calculated independently.In both systems, both the excess thermal conductivity λ(T,?) - λ(T, 0) and the ratio λ(T, ?)?λ(T, 0) are sole functions of density with a remarkable degree of precision.The variation of the thermal conductivity with density could be predicted quit accurately with the aid of the theory due to Mason.     

Kinetic fragility of binary and ternary glass forming liquid mixtures

The experimental studies of liquid fragility in miscible binary and ternary glass forming mixtures reveal a general observation of the negative deviation in fragility upon mixing from the linear average of those of the components. Further analyses from ideal, near ideal to non-ideal mixing modes show that the deviation magnitude does not increase monotonically with mixing enthalpy, and a moderate intermolecular interaction would generate a largest reduction in fragility. Four eutectic systems, methyl-o-toluate-methyl-p-toluate, ZnCl₂-AlCl₃, glycerol-water, and fructose-water, are studied to locate the composition where the largest fragility deviation occurs in phase diagrams. It is found that the compositions with the fragility minima do not coincide with the eutectic points. The results partly explain the experimental observation that the best glass forming region is not located at the eutectic composition.     

Instabilities in binary mixtures of one-dimensional quantum degenerate gases

We show that one-dimensional binary mixtures of bosons or of a boson and a spin-polarized fermion are Luttinger liquids with the following instabilities: (i) For different particle densities, strong attraction between the mixture components leads to collapse, while strong repulsion leads to demixing, and (ii) For a low-density mixture of two gases of impenetrable bosons (or a spin-polarized fermion and an impenetrable boson) of equal densities, the system develops a gap and exhibits enhanced pairing fluctuations when there is attraction between the components. In the boson-fermion mixture, the pairing fluctuations occur at finite momentum. Our conclusions apply to mixtures both on the continuum and on optical lattices away from integer or fractional commensurability.     

Thermal diffusion in binary mixtures containing molecular gases II: mixtures of N2 with He,Ne, Ar,and Kr and of CO2 with He and Ar

Expressions developed for the thermal diffusion factor, αT, for binary mixtures containing molecular species have been tested for six different atom-molecule interactions. Specifically, the interactions between N₂ and He, Ne, Ar and Kr, plus the interactions between CO₂ and He, Ar, have been examined, in each case using at least two competing modern potential energy surfaces. Detailed expressions in both the ‘total-energy-flux’ and the ‘two-flux’ representations have been developed, and the importance of the anisotropic components of the intermolecular potential energy surfaces in determining the thermal diffusion factor for such mixtures has been determined.     

Density dependence of electric properties of binary mixtures of inert gases

A computational study of the density dependence of the refractivity and dielectric constants, the electric-field induced second harmonic generation (ESHG) hyperpolarizabilities and of the Kerr constants of binary mixtures of helium, neon and argon is presented. Potentials and interaction properties of the homonuclear A₂ and heteronuclear AB dimers (A,?B=He, Ne, Ar) are taken from a previous study [J. López Cacheiro, B. Fernández, D. Marchesan, S. Coriani, C. Hättig, A. Rizzo. Molec. Phys., 102, 101 (2004)]. Dispersion coefficients for the second virial coefficients allow for the determination of the density dependence at any frequency far from the lowest resonance. Fully quantum mechanical results are presented and a comparison with the corresponding classical estimates is discussed. Deep minima are predicted to occur in the ESHG second virial coefficient curve drawn as a function of the molar fraction of one of the components in binary mixtures of He/Ar and Ne/Ar. This phenomenon, observed over a wide range of temperatures, should be easily verifiable experimentally.     

Kinetics of nonresonant vibrational energy exchange in binary mixtures of molecular gases

The variation of the temperature of a gas during vibrational relaxation is a unique source of information on the kinetics of vibrational-vibrational (VV) and vibrational-translational (VT) energy exchange, and the characteristic parameters of the temperature curve are related to the characteristic times of the VV and VT processes. The effect of kinetic cooling, in which VV exchange leads to a temperature drop, has been studied quite extensively [1]. It was shown in [2] that the characteristic parameters of the cooling curve are uniquely related to the VV and VT relaxation times.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 15–18, October, 1988.     

Diffusion and thermal diffusion in binary mixtures of sulphur hexafluoride with noble gases

Diffusion coefficients and thermal diffusion factors are reported for binary mixtures of sulphur hexafluoride with noble gases. The results are compared with theoretical values calculated by means of the Chapman-Enskog theory, spherical potentials for the like interactions and multi-parameter anisotropic potentials for the unlike interactions.     

On thermal diffusion in binary and ternary Lennard-Jones mixtures by non-equilibrium molecular dynamics

Molecular simulation appears to be an alternative to experiment for the estimation of transport and thermodynamics properties of fluid mixtures, which is of primary importance in the evaluation of the initial state of a petroleum reservoir. In this study, a non-equilibrium molecular dynamics algorithm has been applied to mixtures of Lennard-Jones spheres in order to compute the thermal diffusion process. The pertinence of such an approach to simple alkane mixtures is shown. The separate influences on the thermal diffusion of the molecular features in binary equimolar mixtures are then summarized. Simulations on binary non-equimolar mixtures have been performed as well. The results indicate an increase in the thermal diffusion process with increasing molar fraction of the lightest component. Moreover, this increase is enhanced with increasing difference in the number of carbons between the two alkanes. Then, a simple method, which yields results consistent with simulations, is proposed to predict thermal diffusion for the whole range of molar fractions starting only from the equimolar value. Finally, for ternary mixtures, the law of the corresponding states is shown to be valid when the appropriate mixing rules are applied, which allows the estimation of thermal diffusion in such mixtures from equivalent binary mixtures.     

The viscosity and diffusion coefficients of the binary mixtures of xenon with the other noble gases

This paper presents new experimental data for the viscosity of binary mixtures of xenon with the remaining monatomic gases, helium, neon, argon, and krypton. The measurements have been performed in a high precision oscillating-disk viscometer at atmospheric pressure and within the temperature range 25–500°C. The data have an estimated uncertainty of ±0.1% at 25°C increasing to ±0.3% at 500°C. The collision integrals for the interactions of xenon with the other monatomic species conform to the extended law of corresponding states formulated by Kestin, Ro and Wakeham. For each binary interaction the scaling parameters σ_ij and ∈_ij have been obtained. The ensemble of experimental results can be correlated by means of the appropriate kinetic theory expressions reinforced by the extended law of corresponding states. The deviations do not exceed 0.5%. The binary diffusion coefficients were calculated from the measured mixture viscosity and compared with the available experimental results. The standard deviation was estimated as ±2% which is within the mutual uncertainty of the two sets.     

Enskog’s kinetic theory of dense gases for chemically reacting binary mixtures, II: Light scattering and sound propagation

Enskog’s kinetic theory for a symmetric moderately dense reaction A+A?B+B is used to determine Fick’s and Fourier’s law. The transport coefficients of diffusion, thermal-diffusion rate and thermal conductivity are represented graphically for endothermic and exothermic reactions and are analyzed as a function of the activation energy and of the density of the mixture. The Onsager reciprocity relations are numerically investigated and verified. The problems related to sound propagation and light scattering are investigated for such a mixture and it is shown that the influence of chemical reactions on phase velocity, attenuation coefficient and light scattering spectra is more pronounced for rarefied gases although there is a considerable change in these quantities as the mixture becomes denser.     

Optical effects in ternary and quaternary compound MESFETs

Light-generated voltages have been evaluated theoretically when the transparent gate of GaInAs and GaInAsP MESFETs is illuminated with optical radiation of varying intensities. Using these values the source-drain current under various light intensities has been calculated. Theoretical values of gain and optical gain as functions of the gate voltage for a given intensity are also presented for comparison.     

Cluster aspects of binary and ternary fission

On the basis of the statistical approach and calculation of the potential energy of the scission configurations, binary and ternary fissions are described. The text was submitted by the authors in English     

Sequential character of low-energy ternary and quaternary nuclear fission

An analysis of low-energy true ternary (quaternary) nuclear fission leads to the conclusion that these fission modes have a sequential two-step (three-step) character such that the emission of a third particle (third and fourth particles) and the separation of fission fragments occur at distinctly different instants, in contrast to the simultaneous emergence of all fission products in the case of onestep ternary (quaternary) fission. This conclusion relies on the following arguments. First, the emission of a third particle (third and fourth particles) from a fissile nucleus is due to a nonevaporative mechanism associated with a nonadiabatic character of the collective deformation motion of this nucleus at the stages preceding its scission. Second, the axial symmetry of the deformed fissile compound nucleus and the direction of its symmetry axis both remain unchanged at all stages of ternary (quaternary) fission. This circumstancemakes it possible to explain themechanism of the appearance of observed anisotropies and T — odd asymmeries in the angular distributions of products of ternary (quaternary) nuclear fission. Third, the T —odd asymmetry discovered experimentally in ternary nuclear fission induced by cold polarized neutrons obeys the T —invariance condition only in the case of a sequential two-step (three-step) character of true ternary (quaternary) nuclear fission. At the same time, this asymmetry is not a T —invariant quantity in the case of the simultaneous emission of products of true ternary (quaternary) nuclear fission from the fissile compound nucleus.     

All-optical conversion scheme: Binary to quaternary and quaternary to binary number

To achieve the inherent parallelism in optics a suitable number system and efficient encoding/decoding scheme for handling the data are very much essential. Binary number is accepted as the best representing number system in almost all types of existing electronic computers. But, binary number (0 and 1) is insufficient in respect to the demand of the coming generation. Multi-valued logic (with radix >2) can be viewed as an alternative approach to solve many problems in transmission, storage and processing of large amount of information in digital signal processing. Here, in this paper all-optical scheme for the conversion of binary to quaternary number and vice versa have been proposed and described. Simulation has also been done. In this all-optical scheme the numbers are represented by different discrete polarized state of light.     

Theoretical calculation of transport properties of the noble gases He and Ne and their binary mixtures at low density

Using the Tang-Toennies potential model and a set of expressions given by J. Kestinet al., we calculate the transport properties of the two noble gases He and Ne and of their binary mixtures, based upon the calculation of the interaction potential. Our calculated results for the transport properties are restricted to low densities but cover the full temperature interval extending from 50 K to the onset of ionization; the mole fraction of the binary mixtures isx ₁:x ₂=0.25:0.75. Our results are comparable to the best theoretical results given by J. Kestinet al.     

Magnetic,electrical and structural properties of some ternary and quaternary spinels with chromium

Spinel compounds with the general formulas ACr₂X₄ and ACr_2−xB_xX₄ (where A=Cd, Zn, Hg, Ga, Cu; X=S, Se, Te, O; B=Ga, In, Sb), including also substitution of two different cations in the tetrahedral subarray, exhibit different correlations of the magnetic and electrical properties. These properties are correlated with the ionic radii of cations and anions. The solid solutions of the boundary compounds reveal, e.g. correlations of metallic conductivity and a semiconductor–metal phase transition. In some spinel solid solutions the latter phase transition is accompanied by the magnetic phase transitions, i.e. either AF-F or Fi-F. Magnetic and electrical properties and their correlations in different spinel series with chromium are discussed in the frames of the phase diagram of the spinel-type compounds with chromium. Different mechanisms leading to the spin-glass state are discussed and illustrated.     

Plasma radiation emitted by dense mixtures of rare gases excited by an electron beam and by a discharge

An experimental investigation was made of the radiation emitted from a plasma formed by rare gases (He, Ne, Ar, Kr, Xe) excited by a beam of electrons with different parameters and by discharge pulses (P= 0.1–0.5 atm, I=1 kA, U=10–15 kV, C=0.25 F). An investigation was made of the spectral composition and time characteristics of the radiation, and of their dependences on the excitation conditions. New molecular bands were observed in the near-ultraviolet and visible ranges. The uniquely large widths of these bands could be of interest in the amplification of light in a wide spectral range.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 56–73, January, 1992.     

Electrical resistivity of liquid binary and ternary alloys

New method of calculation of the electrical resistivity of liquid and amorphous alloys is presented. The method is based on the Morgan–Howson–S̆aub (MHS̆) model but the pseudopotentials are replaced by the scattering matrix operators. The Fermi energy is properly determined by the accurate values of the phase shifts. The model depends on a very small number of universal parameters and gives stable results. The calculated values of the resistivity agree well with available experimental data for a substantial number of binary alloys. Moreover, the results for some ternary alloys were also obtained.