Structural surface charge

Structural surface charge density, defined as the number of Coulombs per square meter, as a result of isomorphic substitutions in soil minerals. 

The net permanent structural surface charge density, denoted gq and measured in coulombs per square meter (C/m2), is created by isomorphic substitutions in minerals [4]. These substitutions in clay minerals produce significant surface charge only in the 2 1 layer types. In these minerals, Co < 0 invariably because of structural cation substitutions. The relation between gq and the layer charge jc is [3]... 

TABLE 2 Values of the Fraction of Condensed Counterions, q>0(x) in Eq. (9), for Two Values of the Structural Surface Charge Density, [Pg.220]

Dendrimers such as poly(amidoamine) (PAMAM) and poly(propylenimine) (PPI) have also been studied for gene delivery in vitro and in vivo due to their high transfection efficiency. However, the toxicity of the dendrimers is of major concern for their medical use. Generally, in vivo toxicity of dendrimers is related to various factors, including their chemical structure, surface charge, generation and the dose of dendrimer used. Surface modification with PEG or replacement with low generation dendrimers have been reported to be able to improve the biocompatibility of these biomaterials. ... 

This diffuse double-layer approach can be applied to describe the EDL of particles, if charges on particle surface are only permanent structural surface charges originating from isomorphic substitutions of ions in a clay crystal lattice (e.g., montmorillonite, which is a typical example of infinite flat plates with a constant charge density [19]) or they form by the adsorption of potential determining ions (e.g., Ag+ ions on a Agl surface is an example of the case of charged particles with constant potential [1,33,38]) and the diffuse swarm of indifferent electrolyte ions compensates surface charges. 

Yeskie M A and Harwell J H 1988 On the structure of aggregates of adsorbed surfactants The surface charge... 

Storage of electricity and batteries, (MacDiarmid), 368 Structures, tangled, diagrammed after reduction at cathodic potentials, 345 Surface charge... 

Formation from Template Surfaces Recently, a new method for the preparation of LUV was reported by Lasic et al. (1988). The method is based on a simple procedure which leads to the formation of homogeneous populations of LUV with a diameter of around L vim. Upon addition of solvent to a dry phospholipid film deposited on a template surface, vesicles are formed instantly without any chemical or physical treatment. The formation of multilamellar structures is prevented by inducing a surface charge on the bilayers. The size of the vesicles is controlled by the topography of the template surface on which the phospholipid film was deposited (Lasic, 1988). 

FIG. 1 Geometries of electrolyte interfaces, (a) A planar electrode immersed in a solution with ions, and with the ion distrihution in the double layer, (b) Particles with permanent charges or adsorbed surface charges, (c) A porous electrode or membrane with internal structures, (d) A polyelectrolyte with flexible and dynamic structure in solution, (e) Organized amphophilic molecules, e.g., Langmuir-Blodgett film and microemulsion, (f) Organized polyelectrolytes with internal structures, e.g., membranes and vesicles. 

A question of practical interest is the amount of electrolyte adsorbed into nanostructures and how this depends on various surface and solution parameters. The equilibrium concentration of ions inside porous structures will affect the applications, such as ion exchange resins and membranes, containment of nuclear wastes [67], and battery materials [68]. Experimental studies of electrosorption studies on a single planar electrode were reported [69]. Studies on porous structures are difficult, since most structures are ill defined with a wide distribution of pore sizes and surface charges. Only rough estimates of the average number of fixed charges and pore sizes were reported [70-73]. Molecular simulations of nonelectrolyte adsorption into nanopores were widely reported [58]. The confinement effect can lead to abnormalities of lowered critical points and compressed two-phase envelope [74]. 

Table 1 provide definitive evidence that the redon surrounding the site is, indeed, the pectinolytic active site as first hypothesized from the localization of the surface charges on tne PelC structure. 

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