Flow of a Nonlinearly Viscous Fluid over the Surface of a Rotating Flat Disk

The flow of a nonlinearly viscous (power-law) fluid over the surface of a rotating flat disk is investigated. A solution form which makes it possible to reduce the complete system of partial differential equations to a system of ordinary differential equations is found. This system is integrated using the Runge-Kutta method and reduction to a Cauchy problem on the basis of Newton's method. The velocity and pressure fields in a power-law fluid film flowing over the surface of a rotating flat disk are found numerically.     

A Study of Radial Mixing in a Continuous Flow-through Apparatus

The structure of flows was studied experimentally in continuous flow-through apparatus in various flow modes.     

A new approach to the problem of atomization in electrothermal atomic absorption spectrometry

We established that the partial pressure of oxygen in the graphite furnace is several orders of magnitude higher than is explained by the thermodynamic equilibrium of the O₂ + 2C = 2CO reaction. Taking this into account has led us to some new conclusions for thermal destruction, atomization and dissociation of the oxygen-containing compounds. It explains why some elements are reduced to the metal on graphite, while other elements are vaporized as the oxide. For the elements vaporized as the oxide, it is shown that there is good agreement between the calculated thermal dissociation temperature of the metal oxide and the observed appearance temperature. For these metals, the atomization of the oxides proceeds by their thermal dissociation without direct participation of carbon in the reduction process. The presence of oxygen in the purge gas accounts for anomalous curvature in, for example, the Sn calibration curve, large variations in sensitivity for some elements (Ga, Ge, Sb, Se, Sn) comparing gas-stop and full-flow modes of atomization and the enhancement of sensitivity for some elements in oxygen-activated graphite furnaces.     

Modeling of the Concentration Field of Solid Phase in a Hydrocyclone in Suspension Separation by Pressure Flotation

A mathematical model of suspension separation by pressure flotation in a hydrocyclone was developed. The continuity equation was solved numerically for a flux of particles of the solid phase in a flow of a non-Newtonian suspension in a hydrocyclone. The concentration field of solid particles was determined. The effect of the defining similarity criteria on the distribution of concentrations was studied.     

Light-driven advanced oxidation processes in the disposal of emerging pharmaceutical contaminants in aqueous media: A brief review

1. Download : Download high-res image (179KB)
2. Download : Download full-size image

     

Rearrangements of cyclopropenes into five-membered aromatic heterocycles: mechanistic aspect

This review covers rearrangements of cyclopropenes into aromatic five-membered heterocyclic compounds, namely furans and pyrroles; accompanied by small ring cleavage proceeding in the presence of catalytic amounts of transition metals, Lewis acids, or under UV irradiation.     

Differential Surface Stress of Single-Crystal Gold(111) in a Potassium Chloride Melt

The derivative of the surface stress by the charge (q-estance) for the (111) face of single-crystal gold in a KCl melt is measured as a function of potential, temperature, and ac frequency. The derivative alters its sign thrice at relatively low temperatures, giving rise to two extremums in the potential dependence of the surface stress. One is a cathodic maximum, which corresponds to the potential of zero charge. The other, in the anodic range, is due to the chlorine adsorption, which results in the surface recharging. An additional surge of the amplitude and a double change of the phase in it occur between anodic zeros. Regularities are discussed and the results are interpreted within a model of chemical interaction between the adsorbent and adsorbate.     

Photoadsorption, photooxidation and photodecomposition of simple molecules on alkali halide surfaces

Data have been obtained on the activities of 19 alkali halides in photoadsorption of O₂ and CO₂, photooxidation of H₂ and CO and photodecomposition of H₂O and CO₂.

---

19 O₂ CO₂, H₂ CO H₂O CO₂.

     

Viscous and elastic properties of the nematic in the tetrapalladium organyl-pentadecane system

Temperature dependences of the dielectric anisotropy ?_a, effective rotational viscosity \(\tilde \gamma \), and elastic modulus K ₁₁ of the nematic phase of the tetrapalladium organyl-pentadecane system containing 55 wt % pentadecane have been experimentally studied. The quantities ?_a, \(\tilde \gamma \), and K ₁₁ are shown to decrease: ?_a decreases by a factor of about 2.5; \(\tilde \gamma \), by almost two orders of magnitude; and K ₁₁, by more than an order of magnitude. It is found that an applied electric field induces growth of tetrapalladium organyl crystals at 6–9°C above the nematic-crystallosolvate phase transition temperature.