Particle coating

Figure Bl.17.8. Iron oxide particles coated with 4 nm of Pt in an m-planar magnetron sputter coater (Hennann and Mtiller 1991). Micrographs were taken in a Hitachi S-900 in-lens field emission SEM at 30,000 primary magnification and an acceleration voltage of 30 kV. Image width is 2163 nm.

Capillary Electrochromatography Another approach to separating neutral species is capillary electrochromatography (CEC). In this technique the capillary tubing is packed with 1.5-3-pm silica particles coated with a bonded, nonpolar stationary phase. Neutral species separate based on their ability to partition between the stationary phase and the buffer solution (which, due to electroosmotic flow, is the mobile phase). Separations are similar to the analogous HPLC separation, but without the need for high-pressure pumps, furthermore, efficiency in CEC is better than in HPLC, with shorter analysis times. 

This picture of a fresh particle coating shows the characteristic topology of the PSA. 

FIGURE 3 Scanning electron micrograph (1200x magnification) of the surface of a porous alumina particle coated with poly(diphenoxy-phosphazene). Surface nitration, reduction, and glutaric dialdehyde coupling immobilized enzyme molecules to the surface. (From Ref. 23.)... 

Figure 10.5 Principle of operation of a catalyst particle coated with a permselective membrane (a) selective addition of reactants, (b) selective removal of products.

Electrophoresis measurements provide a qualitative indication of the assembly of polymer multilayers on colloids [49,50], The -potential as a function of polyelectrolyte layer number for negatively charged polystyrene (PS) particles coated with poly(diallyldimethylam-monium chloride) (PDADMAC) and poly(styrenesulfonate) (PSS) are displayed in Figure... 

FIG. 5 SEM micrographs of (a) uncoated PS latices and (b) polyelectrolyte-modified PS latices coated with S1O2/PDADMAC. An increase in snrface ronghness and diameter can be clearly seen for the particles coated with Si02/PDADM AC (compare b with a). (From Ref. 58.)... 

Synthesis of composite particulates with tailored morphologies using dry particle coating... 

Semi-conducting layer of Electrolyte (NR4+I7I2) fine Ti02 particles, coated. . . with monolayer of dye... 

Cheng, X. X., Studies of Uniformity of Particle Coating in Fluidized Beds, Ph.D. Dissertation, West Virginia University, Morgantown, WV (1993)... 

Litster, J. D., and Ennis, B. J., Granulation, Pelletisation, and Particle Coating, short course given at IChemE - Australia, Gold Beach, Australia (1994)... 

Figure 29 (Qin and Liu, 1982) shows the behavior of individual particles above the distributor recorded by video camera of small clusters of particles, coated with a fluorescent material and spot-illuminated by a pulse of ultra violet light from an optical fiber. The sequential images, of which Fig. 29 just represents exposures after stated time intervals, were reconstructed to form the track of motion of the particle cluster shown in Fig. 30. Neither this track nor visual observation of the shallow bed while fluidized, reveal any vestige of bubbles. Instead, the particles are thrown up by the high velocity jets issuing from the distributor orifices to several times their static bed height.

Spouted beds have been used for drying and low-temperature chemical-treatment operations. Examples are the low-temperature roasting of agricultural products, and particle-coating and crystal-growth operations. 

Colloidal gold A suspension (or colloid) of submicrometer-sized particles of gold in a fluid, usually water. A colloidal gold conjugate consists of gold particles coated with a selected protein or macromolecule, such as an antibody, protein A or protein G. Because of their high electron density, the gold particles are visible in the electron microscope without further treatment. 

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