Dispersion isotropic

As has been noticed by Gelbart and Gelbart [7], the predominant orientational interaction in nematics results from the isotropic dispersion attraction modulated by the anisotropic molecular hard-core. The anisotropy of this effective potential comes from that of the asymmetric molecular shape. The coupling between the isotropic attraction and the anisotropic hard-core repulsion is represented by the effective potential... 

In Figure 2.9.8(b), the mean traveling time of a neutral tracer across the percolation duster is plotted versus the Pedet number [43]. Two regimes can be identified, namely isotropic dispersion (Pe C 1) and mechanical dispersion (Pe > 1) with a crossover dose toPe 1. In the latter case, the data can be represented by a power law... 

In conclusion, we believe that our ability to observe higher atropisoraeric excesses from Irradiations of BN in cholesteric mesophases than from thermal lsomerlzations can be traced to the larger interaction energies associated with the excited state species and its environment. The cumulative effect of these Interactions is manifested more specifically on a reactive solute when the solvent molecules are uniquely ordered than when they are isotropically dispersed. 

For the calculation of A(r), the attractive van der Waals force between two layers separated by r, we start with an isotropic dispersion interaction of the form = B/r6 between point charges. After integration over one layer we find a force per unit area... 

Mulder F, Thomas GF, Meath WJ (1980) A critical study of some methods for evaluating the C6, C8 and C10 isotropic dispersion energy coefficients using the first row hydrides, CO, C02 and N20 as models. Mol Phys 41 249-269... 

The transport associated with a line source of contaminant was also studied for the same data set (anisotropic media, isotropic dispersion). The model, besides providing numerical details of the simulation (maximum concentration value) also shows (Figure 3.10) the three-dimensional distribution of the contaminant for two cutting planes. The migration of the contaminant concentration for the line source has a wider distribution in the horizontal and transversal planes as shown in the figure. The contaminant concentration meets the CMC and CCC criteria just at 50%... 

In the general case, the scattering fiom a homogeneous and isotropic dispersion of spherical particles (pores) can be written as the product of,... 

Table 3. Isotropic dispersion energy coefficients and ratios Cg/C and C JC (in atomic units) for various methods, described in the text...

A microemulsion is a thermodynamically stable isotropic dispersion of two relatively immiscible liquids, consisting of microdomains of one or both liquids stabilized by a interfacial film of surface-active molecules. In practice, one often identifies the microemulsion by the formation of a clear isotropic mixture of the two immiscible liquids in the presence of appropriate emulsifiers. In a phase diagram, such region is referred as the microemulsion phase. It has been shown that microemulsion regions consist of different microstructures (1,2), e.g., water-in-oil (W/0), oil-in-water (0/W),... 

Microemulsions are thermodynamically stable isotropic dispersions of oil in water (o/w) or of water in oil (w/o) containing domains of nanometer dimensions stabilized by an interfacial film of surfactant(s). The most typical oil phases are alkanes, the choice of cyclic or aromatic hydrocarbon being dependent on further application. Extensive study of microemulsions has been stimulated by their great potential for practical applications in different fields [1,2] such as pharmaceuticals, cosmetics, enhanced oil recovery and material science (catalysts, semiconductors, etc.). 

A molecular material consisting of a homogeneous and isotropic dispersion of monodisperse oUgomers in a transparent homogenous, linear and isotropic matrix is considered. Tqj and are assumed equal. The oscillator strengths and the two-photon absorption strengths associated to the one- and two-photon absorptions of interest have then the following expressions ... 

E. A. Forgy and W. C. Chew, A time-domain method with isotropic dispersion and increased stability on an overlapped lattice, IEEE Trans. Antennas Propag., vol. 50, no. 7, pp. 983-996, July 2002.doi 10.1109/TAR2002.801373... 

Micro-emulsions, as noted originally by Schulman in 1943, are transparent, seemingly homogeneous solutions of water, oil, surfactant, and an alcohol- or amine-based co-surfactant. These isotropic dispersions of two immiscible liquids such as oil and water are stabilized by the presence of emulsifier(s) (surfactant molecules that can be cationic, anionic, or neutral), which are located at the interfaces between oil and water domains. The most common examples are the water-in-oil (W/O) and the oil-in-water (OfW) micro-emulsions. The use of micro-emulsions in the synthesis of materials allows size-selective growth of small particles in water droplets homogeneously entrapped in a hydrocarbon solvent. The important properties are governed mainly by the water-to-surfactant molar ratio. 

Microemulsions are clear, isotropic dispersions of water or oil droplets 10-100 nm in diameter dispersed in a continuous oil or water phase and stabilized by an interfacial film of surfactants. Due to these unique properties, microemulsions are relevant in a variety of technological processes, including enhanced oil recovery (EOR). Several concepts... 

Grossiord et al. (21) diseuss an additional method termed, by them, the oily isotropic dispersion process. We prefer a more accurate terminology of emulsified microemulsions. The idea is to disperse an oil phase within water by smfactant and to form an L2 phase. This phase is... 

Figure 4 Preparation of W/O/W multiple emulsion by oily isotropic dispersion (emulsified microemulsion). (From Ref 21.)...

This section will review selected papers on the behavior of composites reinforced with more or less isotropically dispersed short fibers. More detailed technological and theoretical mechanical discussions, as well as additional information on composites containing continuous unidirectional or cross-plied fibers, is given by Ashton et al. (1969), Broutman and Krock (1967, 1974), Chamis (1974a), Corten (1966, 1971), Hattori (1970), Parkyn (1970), Schwartz and Schwartz (1968), Tsai et al (1969), and Wu (1974), as well as in the general literature. ... 

Microemulsion polymerization [114] involves the polymerization of oil-in-water and water-in-oil monomer microemulsions. Microemulsions are thermodynamically stable and isotropic dispersions, whose stability is due to the very low interfacial tension achieved using appropriate emulsifiers. Particle nucleation occurs upon entry of a radical into a microemulsion droplet. Microemulsion polymerization allows the production of particles smaller than those obtained by emulsion polymerization. This leads to a higher number of polymer particles, which results in a more compartmentalized system. Under these conditions, the life-time of the polymer chains increases leading to ultra-high molecular weights. Inverse microemulsion polymerization is used to produce highly efficient flocculants. 

The term microemulsion indicates an optically transparent, thermodynamically stable, isotropic dispersion of nanometric-sized droplets of one liquid in another (immiscible) liquid, stabilized by interfacial layers of surfactant molecules. Note that there is no generally agreed extent of solubilization when a micellar solution can be said to have transformed into a microemulsion [99]. However, in case of water solubilization, Pileni [100] indicates that when the [water]/[surfactant] molar ratio (= w) exceeds a value of 15, we have a microemulsion, below which the term reverse micelle is preferred. In this text, this differentiation has not been strictly adhered to instead, a general term reverse microemulsion has often been used as a matter of convenience. 

CNTs in polymer-CNT composites are efficiently debundled and isotropically dispersed in polymer matrices, the efficient interaction between CNT and polymer provides good dispersion and a low percolation threshold, but only relatively low conductivity near and above percolation, frequently around 10 s cm is achieved at close to 2wt% CNT loading [70, 71], The polymer layer in the intemanotube connections is supposed to be the highest resistance section in the electrical pathway. This polymer layer is a barrier to efficient carrier transport between CNTs, and models for conductivity based on fluctuation-induced tunneling have been proposed [72]. A power law related to percolation theory can be used to model conductivity in the following form ... 

The reverse microemulsion method is based on the controlled hydrolysis of tetra-ethoxysilane (TEOS) molecules and their ammonia catalysed condensation like the Stober method, but the reaction milieu is in this case a stable and macroscopically isotropic dispersion of a surfactant and water in a hydrocarbon. In this system the hydrolysis is confined inside the aqueous nuclei where precursors condense to form the nanoparticles. Optimized synthetic protocols and experimental conditions allow one to obtain nanoparticle samples in the dimensional range of about 15-200 nm [70, 76] (Fig. 11). 

A microemulsion is a thermodynamically stable isotropic dispersion of two immiscible liquids, where the microdomain of either or both liquids is stabilized by an interfacial film of surfactant molecules. In water-in-oil microemulsions, the aqueous phase is dispersed as microdroplets (typically 1-50 nm in diameter) surrounded by a monolayer of surfactant molecules in the continuous hydrocarbon phase. The size of the reverse micelle is determined by the molar ratio of water to surfactant ... 

A qualitative phase diagram or phase map study performed on these systems over the temperature interval (-20 +80) C, keeping constant both the surfactant/hydrocarbon and the alcohol/hydrocarbon ratio, showed that, as the water content is increased, four macroscopically different structure-regions may be identified I°- an optically transparent region, where the system is a stable and isotropic dispersion of water spherical droplets in a continuous oily phase (1-4-5) ... 

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