Dispersion suspensions

A classification by chemical type is given ia Table 1. It does not attempt to be either rigorous or complete. Clearly, some materials could appear ia more than one of these classifications, eg, polyethylene waxes [9002-88 ] can be classified ia both synthetic waxes and polyolefins, and fiuorosihcones ia sihcones and fiuoropolymers. The broad classes of release materials available are given ia the chemical class column, the principal types ia the chemical subdivision column, and one or two important selections ia the specific examples column. Many commercial products are difficult to place ia any classification scheme. Some are of proprietary composition and many are mixtures. For example, metallic soaps are often used ia combination with hydrocarbon waxes to produce finely dispersed suspensions. Many products also contain formulating aids such as solvents, emulsifiers, and biocides. 

Lm are obtained. These atomizers are specially suitable for dispersing suspensions that would tend to clog nozzles. 

Davis, R.H. and Gecol, H., 1994. Hindered settling function with no empirical parameters for disperse suspensions. American Institution of Chemical Engineers Journal, 40, 570-575. 

Process parameter Polymerization type Emulsion -> Dispersion -> Suspension... 

Surfactants may increase the solubility of the drug via micelle formation, but the amounts of material required to increase solubility significantly are such that at least orally the laxative effects are likely to be unacceptable. The competition between the surfactant micelles and the absorption sites is also likely to reduce any useftd effect and make any prediction of net overall effect difficult. However, if a surfactant has any effect at all, it is likely to be in the realm of agents that help disperse suspensions of insoluble materials and make them available for solution. Natural surfactants, in particular bile salts, may enhance absorption of poorly soluble materials. 

Relaxation studies have shown that the attachment of an ion to a surface is very fast, but the establishment of equilibrium in wel1-dispersed suspensions of colloidal particles is much slower. Adsorption of cations by hydrous oxides may approach equilibrium within a matter of minutes in some systems (39-40). However, cation and anion sorption processes often exhibit a rapid initial stage of adsorption that is followed by a much slower rate of uptake (24,41-43). Several studies of short-term isotopic exchange of phosphate ions between aqueous solutions and oxide surfaces have demonstrated that the kinetics of phosphate desorption are very slow (43-45). Numerous hypotheses have been suggested for this slow attainment of equilibrium including 1) the formation of binuclear complexes on the surface (44) 2) dynamic particle-particle interactions in which an adsorbing ion enhances contact adhesion between particles (43,45-46) 3) diffusion of ions into adsorbents (47) and 4) surface precipitation (48-50). 

Equation 2 describes the growth of each individual particle when its growth rate is determined by the diffusion of the solute from the bulk of the solution to the particle surface. The total consumption of solute from the solution may be obtained by expressing the growth rate as dn/dt = dV/dt = -4irr dr/dt, and adding the values of dn/dt for all the particles. This is simplest for a mono-disperse suspension, but may also be done for a polydisperse system. See Reference ( 3), page 301, and (34,35). ... 

The application of fullerene on the surfaces has an essential advantage in the studies with cell cultures as in this case we can obtain the maximum contact of cells with fullerene - cells adhere on the surface and colonize it as a confluent monolayer. That is the basic difference from the water-soluble complexes and micro-dispersed suspensions of fullerene C60. The pro-/antioxidant activities of fullerene were tested in chemical and biological systems. 

Small-volume parenterals Appearance, color, particulate matter, dispersibility (suspensions), pH, sterility, pyrogenicity, and closure integrity... 

Mill A, Porter G (1982) Photosensitized dissociation of water using dispersed suspensions of n-type semiconductors. J Chem Soc Faraday Trans. 1 78 3659-3669... 

Morrison. I.D.. and S. Ross Colloidal Dispersants Suspensions, b.mulsions amt Foams. John Wiley Sons, Ine. New- York. NY 2002 Scheuing, D.R.. Ed. Ftturier Transform Infrared Spectroscopy in Colloid and Interface Science, American Chemical Society. Washington, DC, 199t... 

Ross. S.. and I.D. Mumson Colloidal Dispersions Suspensions. Emulsions, ami I films 2nd Edition. John Wiley Sons. Inc.. New Yolk. NY. 2U02,... 

Dichlorophenyl) (18) (Fig. 4)14. A finely dispersed suspension of (17) is prepared by adding water (175 ml) into a stirred solution of 2,4,6-trichloro-... 

Colloidal dispersions suspensions and aggregates Viscosity and transient electric birefringence study of clay colloidal aggregation. Physical Review E 65, 21407-21500... 

A condition of flow in which all elements of a fluid passing a certain point follow the same path, or streamline there is no turbulence. Also referred to as streamline flow . A dispersion (suspension or emulsion) of polymer in water. Latex rubber, a heavily cross-linked polymer solid, is produced either by coagulating natural latex or by synthetic means through emulsion polymerization. Example Latex paint is a latex containing pigments and filling additives. 

Dispersion/suspension of the oil and dirt particles in the soap foam, preventing these particles from being redeposited on the surface. 

Mills, A. and Porter, G. 1982. Photosensitised Dissociation of Water, using Dispersed Suspensions of n-type Semiconductors. J.C.S.Faraday Trans.1,78,3659-3669. 

K. Alternatively, one may start with an aqueous ultrasonically dispersed suspension of titania containing HAuCLj, and proceed in the same way,125 but at a spray temperature of 673 K the gold particle size was larger (20 nm). All samples contained Au° and AU2O3 the presence of AU2O3 is surprising after such a temperature of treatment (Section 4.1.1). 

A simple ICP-AES analysis procedure for biological (liver, total diet, egg) materials was developed, based on the extraction with a commercial, water-soluble, tertiary amine solution [13]. CRMs were dispersed in a 10 percent (v/v) amine mixture at pH 8 and the resulting dispersion (suspension) was stirred for 30 min at room temperature. After centrifugation, Al, Ca, Cu, Fe, K, Mg, Mn, Na, and Zn were determined by ICP-AES in the supernatant. 

Refs. [i] Evans ED, Wennerstrom H (1999) The colloidal domain. Wiley-VCH, New York, pp 217 [ii] Hunter RJ (2004) Foundations of colloid science, 2nd edn. Oxford University Press, Oxford, pp 539 [iii] Hamaker HC (1937) Physics 4 1058 Morrison ID, Ross S (2002) Colloidal dispersions. Suspensions, emulsions, and foams. Wiley Interscience, New York, pp 355... 

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