Non-colloids

When high-specific-activity, non-colloidal preparations are administered (a) they are partitioned characteristically between liver and bone (b) in rodents the rate of loss of the liver burden is high (halftime = 6.5 to 10.8 d) (Durbin, 1973) (c) the spleen content is low and (d) autoradiographs show uniform distribution in hepatic cells rather than of phagocytosis of radioactive particles in the reticuloendothelial cells of the liver, spleen, and bone marrow, and there is deposition on bone surfaces. 

These propellants containing mainly fibrous non-colloidal nitrocellulose are usually referred to as Schultze powder, after the inventor—see p. 528. 

Studies have been reported of the complex equilibria present in electrolytically produced supersaturated solutions of Zn2+ in aqueous KOH. Light-scattering and NMR techniques indicate the excess zinc to be present as a solute, rather than a colloid, and the predominant species appears to be the [Zn(OH)4]2 ion.606 However, Raman and potentiometric studies indicate that initially, quasi-colloidal particles, based on Zn(OH)2 and molecules of solvation, are present.607 These particles undergo a first-order decay to yield a solution containing the species [Zn(0H)2(H20)2], [Zn(0H)3H20] and [Zn(OH)4]2-, the actual constitution depending on the concentration. The non-colloidal zinc species are tetrahedral, rather than planar or octahedral. Stability constants for the ions [Zn(OH)n](" 2) ( = 1-3) have been reported.608... 

Colloid science concerns systems in which one or more of the components has at least one dimension within the nanometre (10 9m) to micrometre (10-6m) range, i.e. it concerns, in the main, systems containing large molecules and/or small particles. The adjective microheterogeneous provides an appropriate description of most colloidal systems. There is, however, no sharp distinction between colloidal and non-colloidal systems. 

Town, R.M. and Powell, H.K.J. (1993) Limitations ofXAD resins for the isolation of the non-colloidal humic fraction in soil extracts and aquatic samples. Anal. Chim. Acta, 271, 195-202. 

The practical significance of zeta-potential measurement lies in the fact that strong empirical correlation exists between the measured zeta potential of the system and the properties of the system which are the manifestation of the electrostatic interfacial phenomenon. Since the measurement of zeta potential can be conveniently performed, it becomes an ideal parameter for use in routine testing. Zeta-potential control has been successfully applied to various technical fields involving colloidal and non-colloidal systems. 

Electrodialysis is the combined process of dialysis electrolysis using semipetmeable membranes ro confine the soln under treatment Dialysis is used for separating colloids from non-colloids. Electrodialysis is used for complete removal of small amts of electrolytes, usually on a lab scale Refs 1) P.H. Prausnitz J. Reitstotter, "Elektrophorese, Elektro-osmose, Elektro-dialyse in Fliissigkeiten", Steinkopf, Dresden und Leipzig (1931) 2) A. Weissberger,... 

Adamson (51) proposed a model for W/0 microemulsion formation in terms of a balance between Laplace pressure associated with the interfacial tension at the oil/water interface and the Donnan Osmotic pressure due to the total higher ionic concentration in the interior of aqueous droplets in oil phase. The microemulsion phase can exist in equilibrium with an essentially non-colloidal aqueous second phase provided there is an added electrolyte distributed between droplet s aqueous interior and the external aqueous medium. Both aqueous media contain some alcohol and the total ionic concentration inside the aqueous droplet exceeds that in the external aqueous phase. This model was further modified (52) for W/0 microemulsions to allow for the diffuse double layer in the interior of aqueous droplets. Levine and Robinson (52) proposed a relation governing the equilibrium of the droplet for 1-1 electrolyte, which was based on a balance between the surface tension of the film at the boundary in its charged state and the Maxwell electrostatic stress associated with the electric field in the internal diffuse double layer. 

Sometimes when dealing with a fluid that contains a dispersed particle phase that cannot be considered a component, we treat the suspension fluid as a continuum with a constitutive relation that is modified because of the presence of the particles. An example to be discussed in Chapter 5 is Einstein s modification of the Newtonian viscosity coefficient in dilute colloidal suspensions due to hydrodynamic interactions from the suspended particles. As with molecular motions, the modified coefficient may be determined from measurements of the phenomenon itself by using results from analyses of the particle behavior in the fluid as a guide. These ideas are further expanded upon in Chapter 9 where the behaviors of concentrated suspensions of colloidal and non-colloidal particles are examined. 

In the last section we introduced the concept of two asymptotic viscosity limits for shear thinning colloidal suspensions as a function of shear rate. One is the high shear limit which corresponds to high values of the Peclet number where viscous forces dominate over Brownian and interparticle surface forces. Generally this limit is attained with non-colloidal size particles since to achieve large Peclet numbers by increase in shear rate alone requires very large values for colloidal size particles. In this limit, non-Newtonian effects are negligible for colloidal as well as non-colloidal particles. 

Tannins in the stalks are polymerized, non-colloidal procyanidins (HCl index = 35-40) with a reactivity similar to that of tannins in seeds. 

Scatchard and Black (1949) define an isoionic material as one which gives no non-colloidal ions other than hydrogen and hydroxyl. Thus, by their definition, electrodialyzed albumin is isoionic when Z2w2 = (OH-) — (H+), 2 being the molar concentration of protein ion while we have defined it as isoionic when Z2 = o. In practice, the difference between the two definitions is generally negligible. 

Dilatancy is a property that is more common in coarse non-colloidal suspensions than in clays. A suspension is said to be... 

A novel magnetic resonance imaging (MRI) technique, chemically selective NMR imaging, which resolves the separate components of the evolving vertical concentration profiles of 3-component non-colloidal suspensions, is described. This methodexploits the sensitivity of MRI to chemical differences between the three phases to directly image the fluid phase and one of the solid phases, with the third phase obtained by subtraction. 

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