Colloidal liquids

Stuckey, D.C., Rosjidi, M., Leak, D.J., The downstream separation of chiral epoxides using colloidal liquid aphrons (CLAs), "Separations for Biotechnology III" ed. D.L. Pyle, pp.440-446, SCI Publishing, 1994. 

FIG. 13 A colloidal liquid crystal. The rod-like particles point to a preferred diree-tion, called the nematic director. The solvent is disordered. 

See also Colloidal silica gels Colloidal graphite, 12 795 Colloidal liquids, 7 294-295 Colloidal materials, as membrane foulants, 21 664... 

Confocal fluorescence microscopy has been extensively used in cell biology. Single living cells can indeed be studied by this technique visualization of organelles, distribution of electrical potential, pH imaging, Ca2+ imaging, etc. (Lemasters, 1996). Interesting applications in chemistry have also been reported in the fields of colloids, liquid crystals and polymer blends. 

D. Eden and C. Sunshine, in Dynamic Behavior of Macromolecules, Colloids, Liquid Crystals and Biological Systems by Optical and Electro-Optical Methods (H. Watanabe, ed.), pp. 000-000, Hirokawa, Tokyo (1989). 

Colloidal liquid aphrons (CLAs), obtained by diluting a polyaphron phase, are postulated to consist of a solvent droplet encapsulated in a thin aqueous film ( soapy-shell ), a structure that is stabilized by the presence of a mixture of nonionic and ionic surfactants [57]. Since Sebba s original reports on biliquid foams [58] and subsequently minute oil droplets encapsulated in a water film [59], these structures have been investigated for use in predispersed solvent extraction (PDSE) processes. Because of a favorable partition coefficient for nonpolar solutes between the oil core of the CLA and a dilute aqueous solution, aphrons have been successfully applied to the extraction of antibiotics [60] and organic pollutants such as dichlorobenzene [61] and 3,4-dichloroaniline [62]. 

A half century ago, researchers described foams as disperse structures that contain a colloidal liquid, such as a protein solution, as the dispersion medium and a gas or air as the disperse phase ( ], ) The factors principally involved... 

The use of optical methods to study the dynamics and structure of complex polymeric and colloidal liquids subject to external fields has a long history. The choice of an optical technique is normally motivated by the microstructural information it provides, its sensitivity, and dynamic range. A successful application of an optical measurement, however, will depend on many factors. First, the type of interaction of light with matter must be correctly chosen so that the desired microstructural information of a sample can be extracted. Once selected, the arrangement of optical elements required to perform the required measurement must be designed. This involves not only the selection of the elements themselves, but also their alignment. Finally, a proper interpretation of the observables will depend on one s ability to connect the measurement to the sample s microstructure. 

The connection between the observables extracted from optical measurements, and the microstructure of polymeric and colloidal liquids is presented in Chapter 6. This is developed in terms of current models of molecular and particulate dynamics. The study of the dynamics and structure of complex liquids is interdisciplinary, involving physicists, chemists, and chemical engineers. Recognition of this wide audience is reflected in the applications that are included, where examples are drawn from each segment of the community. 

When two or more pure materials mix in a homogeneous way (with their molecules intermixing on a molecular level), the mixture is called a solution. Heterogeneous combinations of materials are called mixtures. Dispersions of small particles that are larger than molecules are called colloids. Liquid solutions are the most common, but any two phases may form a solution. When a pure liquid and a gas or solid form a liquid solution, the pure liquid is called the solvent and the non-liquids are called solutes. When all components in the solution were originally liquids, then the one present in the greatest amount is called the solvent and the others are called solutes. Solutions with water as the solvent are called aqueous solutions. The amount of solute in a solvent is called its concentration. A solution with a small concentration of solute is called dilute, and a solution with a large concentration of solute is called concentrated. 

The radial distribution function plays an important role in the study of liquid systems. In the first place, g(r) is a physical quantity that can be determined experimentally by a number of techniques, for instance X-ray and neutron scattering (for atomic and molecular fluids), light scattering and imaging techniques (in the case of colloidal liquids and other complex fluids). Second, g(r) can also be determined from theoretical approximations and from computer simulations if the pair interparticle potential is known. Third, from the knowledge of g(r) and of the interparticle interactions, the thermodynamic properties of the system can be obtained. These three aspects are discussed in more detail in the following sections. In addition, let us mention that the static structure is also important in determining physical quantities such as the dynamic an other transport properties. Some theoretical approaches for those quantities use as an input precisely this structural information of the system [15-17,30,31]. 

For colloidal liquids, Eqs. (19-21) refer to the excess energy [second term of the right-hand side of Eq. (19)], the osmotic pressure and osmotic compressibility, respectively. They show one of the important features of the radial distribution function g(r), namely, that this quantity bridges the (structural) properties of the system at the mesoscopic scale with its macroscopic (thermodynamic) properties. 

Gel. A glutinous semisolid mass resulting from coagulation of a colloidal liquid in polymer chemistry, a somewhat elastic but not plastic mass. 

In the study of the law of enzyme actions, consideration must be taken of the fact that trypsin is adsorbed by a whole series of substances, and that the enzyme adsorbed may again become active in consequence of the phenomenon of autolysis. The quantity of active enzyme present in a digestive mixture not always being constant in all the phases of the reaction, it is evident that tmder such conditions we can no longer observe the proportionality of time and of the quantity of enzyme. Thus it is that the addition of charcoal powder to a solution of trypsin causes a very perceptible diminution of digestive power. The charcoal, previously kept in a colloidal liquid, such as a solution... 

COALESCENCE - The gathering together of coagulated colloidal liquids into a single continuous phase. 

Colloidal liquid aphrons are a kind of emulsion in which micrometre-size dispersed droplets have an unusually thick stabilizing film and exist clustered together as opposed to either separated, nearly spherical droplets. The stabilizing aqueous film, sometimes called a soapy shell, is thought to have inner and outer surfactant monolayers. Taking this a step further, vesicles are droplets characterized by the presence at their surface of a lipid bimolecular film (bilayer) or series of concentric bilayers. A vesicle can be single or multilamellar and stabilized by natural or synthetic surfactants. Vesicles made from lipid or fat (e.g. phospholipid) bilayers are called liposomes (or, sometimes,/jofyso/wes). 

Turbidity The cloudiness in a liquid caused by a suspension of colloidal liquid droplets, or fine solids. 

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