Effective thermodynamic functions of a gas with solid particles

Using the relaxation formalism of nonequilibrium thermodynamics, a dynamic equation of state and hyperbolic thermal-conductivity equation are derived for a gas with solid particles.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 34, No. 6, pp. 1085–1089, June, 1978.     

Measurement of tangential friction in gas flows with solid particles

We present the results of direct measurements of the force interaction between a gas flow carrying solid particles and the walls of a cylindrical pipe. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 6, pp. 914–918, November–December, 1997.     

On the effluence of gases with solid particles into vacuum

Several viewpoints are presented concerning the process of a kinetic freeze during a spherically symmetric steady effluence of a gas into vacuum.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 22, No. 3, pp. 511–513, March 1972.     

Accumulation of solid particles in convective flows

Accumulation of solid particles suspended in unsteady convective flows is under theoretical investigation. The principal goal is to understand and interpret recent experiments by D. Schwabe [1,2]. Providing that volume particle concentration, nonisothermality, and relative size of particle are small, an effective single-fluid theoretical model is developed. The peculiarity of the obtained model is taking into account the distinction between fluid and particle inertia. This model is further applied to study particle accumulation in different flow setups: in a model oscillatory flow in a canal heated from below and subjected to the modulated gravity and in the Marangoni flow in a half-zone under microgravity conditions. These problems are investigated numerically by means of finite difference technique. We demonstrate, that the developed theoretical model properly describes generic features of particle accumulation in unsteady flows. Particularly, heavy particles tend to leave the centers of vortices, where the flow vorticity is maximal, and accumulate at their periphery. From numerical simulations in a floating zone, we try to clarify particle dynamics in Schwabe’s setup.     

柯达新的固体颗粒分散体滤光染料

本文介绍了柯达公司九十年代提出的新的固体颗粒分散体的滤光染料,着重介绍这些染料的特点和结构,并列举了合成与应用实例。     

Acceleration of solid particles in a channel

On the basis of an anlaysis of the distribution of the parameter of a two-phase flow emerging from a channel we obtain a criterial relation for the velocity disequilibrium of the phases.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 8, No. 1, pp. 16–20, January, 1990.     

Functionalized solid lipid nanoparticles for transendothelial delivery

The objectives of this study were to synthesize and characterize functionalized solid lipid nanoparticles (fSLN) to investigate their interaction with endothelial cell monolayers and to evaluate their transendothelial transport capabilities. fSLN bearing tetramethylrhodamine-isothiocyanate-labeled bovine serum albumin (TRITC-BSA) and Coumarin 6 were prepared using a single-step phase-inversion process that afforded concurrent surface modification with a variety of macromolecules such as polystyrene sulfonate (PSS), poly-L-lysine (PLL), heparin (Hep), polyacrylic acid (PAA), polyvinyl alcohol, and polyethylene glycol (PEG). TRITC-BSA/Coumarin 6 encapsulated in fSLN with composite surface functionality (PSS-PLL and PSS-PLL-Hep) were also investigated. Size and surface charge of fSLN were analyzed using dynamic light scattering and transmission electron microscopy. Transport across bovine aortic endothelial cell (BAEC) monolayers was assessed spectrophotometrically using a transwell assay, and fSLN localization at the level of the cell and permeable support was analyzed using fluorescence microscopy. fSLN with tunable size and surface functionality were successfully produced, and had significant effects on cell localization and transport. Specifically, fSLN with PSS-PLL-Hep composite surface functionalization was capable of translocating 53.2 +/- 8.7 mug of TRITC-BSA within 4 h, with fSLN-PEG, fSLN-PAA, and fSLN-PSS exhibiting near-complete apical, paracellular, and cytosolic localization, respectively. Coumarin 6 was released by fSLN as indicated by dye labeling of BAEC membranes. We have developed a rapid process for the production of fSLN bearing low- and high-molecular-weight payloads of varying physicochemical properties. These findings have impications for drug delivery and bioimaging applications, since due to tunable surface chemistry, fSLN internalization and/or translocation across intact endothelial cell monolayers is possible.     

Vortex simulation for non-axisymmetric collision of a vortex ring with solid particles

This study is concerned with the numerical simulation for the non-axisymmetric collision between a vortex ring and solid particles. The vortex ring convects with its self-induced velocity in a quiescent air, and the half part collides with spherical glass particles. The vortex method for gas-particle two-phase flow proposed by the authors in a prior paper is used for the simulation. The Reynolds number of the vortex ring is 2600, and the particle diameter is 50 μm. The Stokes number, defined as the ratio of the particle response time to the characteristic time of the vortex ring, is 0.74. The simulation clarifies that the particles induce the vortices, having an axis parallel to the convection direction of the vortex ring, inside the vortex ring and that pairs of the positive and negative vortex tubes appear. It also highlights that highly organized three-dimensional vortical structures composed of the streamwise vortices yield the rapid deformation and collapse of the vortex ring.     

Numerical simulation for the transport of solid particles with a vortex ring

The objective of this study is to search for the possibility to transport or deliver small solid particles by a vortex ring. The numerical simulation for the motion of a vortex ring and glass particles is performed. At the launch of a vortex ring into quiescent air, spherical particles are arranged on the cross-section of the vortex ring. The cases of the Stokes number St of 0.01 and 1 are simulated by the vortex method. The simulation for St = 0.01 highlights that the vortex ring involves the particles at the launch and that it can transport the particles at a distance of 5.5 times longer than the initial diameter of the vortex ring. The simulation also clarifies the effect of St on the behavior of the vortex ring and the particle motion.     

The transverse motion of solid particles in a flow with fluctuating shear

We calculate the specific lift which must be experienced by a spherical particle with density different from that of the fluid, in a flow with fluctuating shear.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol.19, No.2, pp. 341–344, August, 1970.     

Discharge of a gas with solid particles from nozzles at critical velocities

Problems of the gas dynamics of two-phase flow with critical discharge conditions are considered. The flow parameters (pressure, density, and velocity of the gas) are calculated in one-dimensional approximation in convergent and cylindrical nozzles. The calculated data are compared with the experimental results obtained by investigating the discharge of a mixture of air and solid particles.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 18, No. 4, pp. 648–652, April, 1970.     

Relationships for a fluidized bed of solid particles

A new theory for a fluidized bed is presented and corroborated by experimental data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 18, No. 6, pp. 1122–1130, June, 1970.     

Thermophoretic levitation of solid particles at atmospheric pressure

Separation and transportation of powders are important processes in various technological applications. Although mechanical, chemical, or electrical methods can provide possible solutions, operational or environmental constraints may require alternative methods. Spreading and levitation of clusters (aggregates) of fluorinated fumed silica nanoparticles placed under atmospheric pressure on a hot plate is reported. The powder spreading in the chamber continued until the temperature-dependent saturation value of the spot radius, which grew linearly with the temperature. Open space experiments clearly demonstrated levitation of the powder clouds. Qualitative physical analysis of the observed phenomena is suggested. The effect of levitation is explained by the lifting thermo-phoretic force emerging in the Knudsen layer of air. The levitation of the powder under atmospheric pressure becomes possible due to the combination of low adhesion of the fluorinated fumed silica clusters to the substrate, low density of the particles and clusters, and their high specific surface area.     

Quenching of an air plasma by solid particles

An analytical expression which describes the quenching of a relatively cold plasma by cold solid particles is used for designing the length of the quenching reactor. The cooling law thus obtained agrees with experimental data.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 38, No. 6, pp. 999–1004, June, 1980.     

Collisional solute release from thermally activated lipid particles

Solid lipid particles were evaluated for their potential as a thermo-activated drug delivery system. Submicron-sized diphenylhexatriene (DPH)/myristyl alcohol particles were produced by an atomization/drying process and the release rate of DPH into sodium dodecyl sulfate (SDS) micellar solutions was measured. The results showed that the presence of micelles and thermal activation was necessary and sufficient for the release of DPH. The initial rate of DPH release was linear for most systems. However, nonlinearity was noted at low micelle concentrations where the rate decreased with time due to the loss of sink conditions with the rising concentration of DPH in the micellar solution. Also at high micelle and particle concentrations, the rate increased with time, which may be due to a loss of particle integrity. Analyzing the data from a design study, the release rate was found to be linearly proportional to particle concentration. In contrast, the rate of release increased with micelle concentration in a nonlinear manner and appeared to approach a plateau at high micelle concentrations. The decrease in rate as the micelle concentration increased is suggestive of a saturable process and may involve a collision-based mechanism.     

Models describing the interaction of particles with a plane solid/liquid interface

Various models depicting particle engulfment or rejection in contact with a plane organic solidification front have been examined and their predictions compared with the experimental results for six particle/matrix systems. The directionally solidified composites were made of different kinds of particles such as nylon, teflon or polystyrene dispersed within biphenyl or naphthalene matrices. The thermodynamic and thermal approaches achieve a good agreement with the experimental results for low solidification rate and particle volume fraction. In order to make the particle engulfment or rejection modelling more complete, a kinetic approach has been developed considering a critical interface velocity above which particles are engulfed and below which particles are pushed. Unfortunately, the related model did not allow the behaviour of particles in front of a plane solid/liquid interface to be successfully predicted.Nomenclature C _P particle specific heat - C _L liquid specific heat - a ₀ atomic spacing - V ₀ atomic volume - kT Boltzman factor - L heat of solidification - r _P particle radius - V _C critical velocity - V _y solidification rate - _L liquid thermal conductivity - _P particle thermal conductivity - _L liquid density - _P particle density - _PL particle/liquid interfacial energy - _PS particle/solid interfacial energy - G _net change in free energy for engulfment - k constant - A empirical constant - b empirical constant - D diffusion coefficient of the liquid - n constant depending on the particle/matrix system     

Preparation and characterization of camptothecin solid lipid nanoparticles

Camptothecin (CA), an antitumor drug, was incorporated into solid lipid nanoparticles (SLNs) prepared by high-pressure homogenization. A Taguchi orthogonal experimental design was used to study the influence of four different variables, with each variable having three value levels on nanoparticle size. Analysis of variance (ANOVA) has been used to evaluate the preparation of CA-SLNs and perform product optimization. The optimized CA-SLNs suspension was lyophilized using mannitol and glucose as cryoprotectants. The physicochemical characteristics of CA-SLNs were evaluated using transmission electron microscopy (TEM), electrophoresis, and differential scanning calorimetry (DSC). The release of camptothecin from CA-SLNs in various media was evaluated using a high-performance liquid chromatography (HPLC) method. The results showed that the concentration of emulsifier and the homogenization pressure had a significant influence on the particle size. The optimized CA-SLNs had an average diameter of about 200 nm, exhibited monodispersity with Dw/Dn of 1.06, and carried a negative charge. The optimal cryoprotectants consisted of 10% mannitol and 5% glucose in nanoparticle suspension. Lyophilized product was reconstituted in distilled water within 0.5 min without change of nanoparticle size. Camptothecin might exist in an amorphous state in SLNs. In vitro results showed that drug release was achieved for up to one week, and the released camptothecin quickly changed to open carboxylate form in the biological pH phosphate buffer. The results indicate that SLNs might be good potential sustained-release delivery vehicles for camptothecin or other lipophilic drugs.     

Heating of three-layer solid aerosol particles by laser radiation

The heating of lidar-irradiated multilayer particles is analyzed theoretically and numerically by solution of the heat conduction equation. The internal intensity and temperature distributions are presented for particles composed of air, quartz, and carbon. It is shown that the heating times of such particles substantially depend on particle radii, layer position, and shell thickness. In particular, the decrease in thickness of the surface carbon layer can result in a reduction of the heating time of multilayer particles.     

Formation and growth of solid particles in shear flow

Formation and growth of solid particles of Sn-15% Pb and Al-40% Zn were studied using a Couette type viscometer in isothermally and continuously cooled shear flows. Solid particles come mainly from broken dendrites in the initial stage of solidification. With increase of solid fraction, solids grow in an equiaxial and merging way in the flow of the partially solidified alloy. Mergence happens between two particles of small misorientation, and merging growth is performed by the growth of protruding parts on the solid-liquid interfaces of the solids.