Mass transfer in nonuniform media

The lattice model was used to derive equations describing diffusion in a nonuniform medium in the absence of local equilibrium at nonzero temperature gradients. Equations are obtained that extend a diffusion equation with fractional derivative in time and a nonlinear diffusion equation, which was previously obtained within the framework of a generalized thermodynamic approach, to cover diffusion in a medium with a nonuniform temperature field.     

Energy transfer in porous anodic alumina/rhodamine 110 nanocomposites

We have used porous anodic alumina (PAA) films as templates for embedding rhodamine 110 (Rh110) molecules and examined their photoluminescence (PL) properties in detail. The analysis of the polarization memory (PM) of PL strongly suggests that there is a significant energy transfer from PAA to Rh110 molecules. The effect of annealing the PAA layer on the PL properties of the nanocomposite has been studied. The results show that the energy transfer becomes more efficient in annealed PAA.     

Simulation parameters of temperature in the process of manufacturing a glass-metal composite

A mathematical model is proposed for solving the problem of the glass cylinder deformation under the action of temperature and pressure in a confined region. Experimental investigations were made to confirm modeling parameters.     

Thermostimulated current of dielectric relaxation in metal-vanadium phosphate glass-metal systems

The nature of the maxima of the thermostimulated current of dielectric relaxation in the thinfilm system metal-vanadium phosphate glass-metal is discussed. The experimental data is analyzed, taking into account the presence of a blocking barrier layer at the metalglass interface and allowing for the fact that the charge carriers in the glass have an activated mobility. The mobility of the charge carriers and their activation energy as well as the energetic position of the impurity levels and their concentration are determined from the curves of the temperature dependence of relaxation current.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 92–100, February, 1977.     

Mass transfer due to cavitation microstreaming

In this paper the influence of the microstreaming, which occurs when a gas bubble vibrates in a viscous liquid, on the mass transfer across the liquid-gas interface, is considered. A systematic theory is developed using results obtained by Davidson and Riley for steady streaming. Particular attention is devoted to two special cases.     

Interface charge transfer process in ZnO:Mn/ZnS nanocomposites

Journal of Nanoparticle Research - TiO2 photocatalysts co-doped with F and Fe were synthesized by a sol–gel method. Synergistic effects of F and Fe in the co-doped TiO2 were verified by NH3...     

Effects of a strong electrical field in thin-film metal-chalcogenide glass-metal structures

The temperature dependence of the conductivity and the shape of the current-voltage characteristic (CVC) of thin-film Mo-chalcogenide glass (CGG)-Mo-Al are analyzed. Four sections can be separated on the CVC. Ohm's law is satisfied on the first section. The dependence of the current intensity (I) on the field intensity (E) on the second corresponds to the Poole-Frenkel (PF) effect. It is established that the temperature dependence of the PF factor has a break at the temperature corresponding to the passage from conductivity because of hole transport over nonlocalized states of the valence band to conduction because of jumps over the localized states of the valence band tail. On the third CVC section I exp[(T)E]. It is assumed that this section is due to the development of a shock ionization process in the CGG film.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 64–71, August, 1979.The authors are grateful to I. A. Korzh and A. N. Alekseev for aid in fabricating the specimens.     

Mass transfer in a two-phase flow in a curvilinear channel

In this paper, the results of an experimental investigation of the distribution of local coefficients of mass transfer on a pipe wall for a flow of a two-phase gas-liquid mixture with a turn of 90° are presented. The mass transfer coefficients were measured by using an electrodiffusion method. It has been shown that the distribution of local mass transfer coefficients on the inner surface of a curvilinear channel is nonuniform both in length and along the perimeter and depends on the content of gas in the two-phase flow.     

Effect of surface modification on dielectric and magnetic properties of metal powder/polymer nanocomposites

Metal nanopowder (Co and Fe)/polymer composites, both with and without surface modification by behenic acid, were fabricated and their dielectric and magnetic properties were measured at 1 GHz to study the effect of surface modification on the electromagnetic properties. The relative permittivity and the real part of the permeability of the composites with surface modified powders were higher than those with unmodified powders. Related dielectric losses remained at almost the same level, but magnetic losses were somewhat increased. The increase of relative permittivity could result from the increased volume fraction of interphase with a slightly higher relative permittivity at the particle/polymer interface than that of the bulk polymer. The increase in the real part of the permeability may be caused by suppression of the induced demagnetizing field due to suppression of eddy currents by a better particle distribution and a decrease in effective agglomerate size because of the surface modification.     

Mass transfer of zinc-containing compounds during filtration combustion in the counterflow regime. 2. Mass transfer at a high content of zinc oxide in the stock

A thermodynamic analysis of the equilibrium composition of the gaseous and condensed products for the ZnO-C-O₂-N₂ system was performed. The characteristics of the filtration combustion and mass transfer of volatile products from model stocks with a high content of zinc oxide were studied. The conditions of combustion of stock samples, degree of extraction of zinc-containing products into sublimate from condensed sample, and the chemical form of zinc-containing compounds released were determined for a wide range of governing parameters.     

Mass transfer enhancement in supercritical fluids extraction by means of power ultrasound

The use of high-intensity ultrasound represents an efficient manner of producing small scale agitation, enhancing mass transfer on supercritical fluids (SF) extraction processes. In this way, a supercritical CO(2) extraction of oil from particulate almonds using power ultrasound was studied. To examine the effect of the acoustic waves all experiments were performed with and without ultrasound. A power ultrasonic transducer for a working frequency of about 20 kHz was constructed and installed inside a high-pressure 5 l SF extractor. The experimental tests were carried out with CO(2) at 280 bar and 55 degrees C. Grounded almonds with an oil content of about 55%, in an amount of 1500 g were deposited inside the SF reactor where the solvent was introduced at a flow rate of 20 kg/h. The results show that the kinetics and the extraction yield of the oil were enhanced by 30% and 20% respectively, when a power of about 50 W was applied to the transducer. The average time of each extraction process was of about 8 h and 30 min. In addition, the transducer was also used as a sensitive probe capable to detect the phase behavior of supercritical fluids when it was driven with low power signals.     

Mass transfer of indium in the In-CdTe structure under nanosecond laser irradiation

The features of mass transfer of indium in high-resistance CdTe crystals under nanosecond irradiation of the In-CdTe structure by laser pulses have been studied and analyzed. The mass transfer coefficients are determined and the average transfer rate of the indium atoms in CdTe under irradiation is evaluated. It is assumed that the concentration diffusion of indium in CdTe and the transfer of impurity atoms by the front of the laser-induced shock wave are not dominant mechanisms of mass transfer under dynamic doping. The most probable process, which provides the formation of the inverse layer in the surface region of the CdTe crystal under nanosecond laser irradiation of the In film, is an transfer of interstitial In atoms due to the thermal fluctuation jumps under the action of the driving force of the thermoelastic stresses and temperature gradient.     

Mass transfer of zinc-containing compounds during filtration combustion in the counterflow regime: 3. Mass transfer at a low content of the zinc-containing component in the initial stock

The regularities of filtration combustion and of the mass transfer of zinc-containing products from model stock compositions with a low content of the zinc-containing component were experimentally studied over a range of governing parameters. The parameters of the combustion of stock samples, degree of extraction of zinc-containing products into sublimate from the condensed sample, and chemical form of the zinc-containing compounds released were determined. The results obtained were discussed.     

Effect of clay surface modification on the structure and electro-optical properties of liquid crystal/clay nanocomposites

FTIR spectroscopy, atomic force microscopy (AFM) and electro-optical measurements were used to study nanocomposites consisting of nematic liquid crystal (LC) ZLI-2293 and organophilic montmorillonite (MMT) nanoparticles. The initial MMT was modified by two different surfactants: octadecylbenzyldimethylammonium chloride (OBDM) and dioctadecylldimethylammonium chloride (DODM). According to spectroscopic results, Van der Waals interactions between the components of the LC/clay composites are stronger in OBDM-MMT case. AFM images of two types of the LC/clay nanocomposites showed different morphology consisting of large-scale structures. Correlation between the spectroscopic results and electro-optical behaviour of the LC/clay nanocomposites was observed. It was inferred that the memory effect is more pronounced for composites with OBDM-MMT due to colloid network formation, whereas the electro-optical contrast is higher for DODM-MMT, where the clay particles are not organized in any ordered structure.