Slipping-plane . 48 suspensions

The presence of surface conductance behind the slip plane alters the relationships between the various electrokinetic phenomena [83, 84] further complications arise in solvent mixtures [85]. Surface conductance can have a profound effect on the streaming current and electrophoretic mobility of polymer latices [86, 87]. In order to obtain an accurate interpretation of the electrostatic properties of a suspension, one must perform more than one type of electrokinetic experiment. One novel approach is to measure electrophoretic mobility and dielectric spectroscopy in a single instrument [88]. 

The electroviscous effect present with solid particles suspended in ionic liquids, to increase the viscosity over that of the bulk liquid. The primary effect caused by the shear field distorting the electrical double layer surrounding the solid particles in suspension. The secondary effect results from the overlap of the electrical double layers of neighboring particles. The tertiary effect arises from changes in size and shape of the particles caused by the shear field. The primary electroviscous effect has been the subject of much study and has been shown to depend on (a) the size of the Debye length of the electrical double layer compared to the size of the suspended particle (b) the potential at the slipping plane between the particle and the bulk fluid (c) the Peclet number, i.e., diffusive to hydrodynamic forces (d) the Hartmarm number, i.e. electrical to hydrodynamic forces and (e) variations in the Stern layer around the particle (Garcia-Salinas et al. 2000). 

Isoelectric point is a pH value, at which electrokinetic potential C on the slip plane is equal to 0, at the participation in ion exchange only of protons H% i.e., in distilled and deionized water. In Western literature it is denoted pi or lEP. Isoelectric point of a mineral is determined by the electrokinetic method, i.e., from the pH value, at which a suspension of its particles has the lowest mobility in the electric field. Isoelectric point. As opposed to the zero charge point, isoelectric point characterizes zero charge of hydrodynamic interface, i.e., conditions when 0. 

With the supposition that the slip layer is thin and the slip velocity is constant, various analyses have been developed in the search for the ideal experimental method to define slip. The Mooney analysis (20) for both tube flow and concentric cylinder flow has been applied to a wide range of materials including polymer solutions (21), filled suspensions (22), semisolid foods (23), fruit purees (24), and ketchups (25). Alternate estimates of slip velocity have been determined experimentally from, parallel plate torsion flow (26), from flow data in channels and inclined planes, and from porous medium geometries (8). 

For the vertical countercurrent scrubbing system shown in Fig. 7.22, the gas-solid suspension flows upward from the bottom of the chamber and the water droplets fall downward. It is assumed that both the gas-solid suspension velocity and droplet velocity are unchanged in the process of scrubbing. It is also assumed that the no-slip condition exists between the particles and gas. The particle concentration across any horizontal plane is assumed to be uniform. 

The first hematologic cell-counting chamber, the hemocytometer, was developed in 1873. A drop of a diluted suspension of blood cells was inserted by capillary action between a glass cover slip and the finely cross-hatched surface of a glass chamber. The blood cells were allowed to setde to a common focal plane. Then, using a microscope, the red blood cells (RBC) within the cross-hatched areas were counted. Eventually, technologists used the hemocytometer to count white blood cells (WBC) and platelets (PLT) as well, first destroying the red blood cells which predominated. Hemocytometers are still used on occasion. 

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