Colloids effects

J) The extreme fineness of iadividual clay particles, which may be of colloidal size ia at least one dimension. Clay minerals are usually platy ia shape, and less often lathlike and tubular or scroU shaped (13). Because of this fineness clays exhibit the surface chemical properties of coUoids (qv) (14). Some clays possess relatively open crystal lattices and show internal surface colloidal effects. Other minerals and rock particles, which are not hydrous aluminosihcates but which also show colloidal dimensions and characteristics, may occur intimately intermixed with the clay minerals and play an essential role. 

Tsang JW, Moffatt JR. (1998) Black-to-color bleed alleviation using nonspecific ionic, pH and colloidal effects, US5853465. 

Colloids are either hydrophilic (water-loving) or hydrophobic (water-hating). Hydrophilic colloids (e.g., proteins, humic substances, bacteria, viruses, as well as iron and aluminum hydrated colloids) tend to hydrate and thereby swell. This increases the viscosity of the system and favors the stability of the colloid by reducing the interparticle interactions and its tendency to settle. These colloids are stabilized more by their affinity for the solvent than by the equalizing of surface charges. Hydrophilic colloids tend to surround the hydrophobic colloids in what is known as the protective-colloid effect, which makes them both more stable. 

ENZYMATIC HYDROLYSIS OF STARCH. Starch is a substance used for storing energy reserve in plants, where it is deposited in the form of starch granules. Starch may be noticed in fruit juice as a milky haze. This haze disappears when the juice is heated, but re-appears after it is cooled to less than 10°C. Like pectin, starch has a protective colloid effect on suspended particles and thus makes juice clarification more difficult. 

The major route to colloidal (effectively water soluble) PAn has been through the chemical oxidation (S2082-) of the monomer in the presence of polymeric steric stabilizers and electrosteric stabilizers (polyelectrolytes), such as poly(vinyl alcohol), polyGV-vinyl pyrrolidone), polyethylene oxide), polystyrene sulfonate), dodecylben-zene sulfonate, and dextran sulfonate. It has been found that the stabilizer can act simultaneously as a dopant, imparting new functionality to the polymer or additional compatibility for the final application. 

The impact of the protective colloid effect on the bitartrate stabilization of a wine varies according to the winemaking methods used. Red wines have a higher phenol content than white wines, and then-condensed tannins have a strong inhibiting effect. 

It is normal to find potassium bitartrate crystals, associated with precipitated condensed coloring matter, in wine with several years aging potential. When phenols condense, they become bulky, precipitate and are no longer able to express their protective colloid effect. 

Table 11.10 Hydrogen transfer of acetophenone catalyzed by amlnoalcohol- and oxazoline-stabilized Ru colloids effect of added ligand in the reaction mixturei i.

The situation is more complicated for nonsolvolytic, bimolecular, reactions, where the observed rate depends on the concentrations of both reactants in both pseudophases. Experiments are generally run under first-order conditions with the concentration of the second reactant in large excess over that of the substrate. In modeling colloidal effects on bimolecular reactions, first-order rate constants [Scheme 3 and Eq. (1)] are written in terms of second-order rate constants and concentrations of the second reactant in each pseudophase. 

Hayakawa K, Kawaguchi M, Kato T. Protective colloidal effects of hydroxypropyl methyl cellulose on the stabUity of sUicone oil emulsions. Langmuir 1997 13 6069-6073. 

H. Hurwitz Usually there is a problem when one tries to measure potentials in site in cells because frequently one is not sure about the bulk potential and there may be a colloidal effect. So I wonder if there could not be such a shift of the potential scale in the case where you use the potassium method. 

H. Hurwitz If you are changing the potassium concentration, you can just have a shift of potential due to the colloidal effect and that might be important because you might be in a situation where you have no bulk potential. 

Two approaches are generally used for modeling the properties of surfactant solutions, pseudophase and the mass action models. The pseudophase model is easier to use and has wider applicability in experimental work. For example, the pseudophase model is the basis for current interpretations of association colloid effects on the rates and equilibria of chemical reactions (Section 6). 

Modeling of association colloid effects on the rates of chemical reactions is based on the pseudophase model. The results from many studies illustrate the explanatory power of this approach and how chemical reactivity in association colloids is interpreted in terms of component... 

Mutual adsorption of ultramicrons. For instance, protective colloidal effects. 

In the figure we see that colloidal effects dictate the viscosity at low shear rates, and then the five S s are important,... 

High levels of rot in the harvest increase juice turbidity and make clarification difficult, due to the protective colloidal effect of glucan produced by Botrytis. A low concentration of rot (less than 5%) tends to facilitate juice clarification, due to a pectinase activity in contaminated grapes that is nearly 100 times higher than in healthy grapes. 

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