Surface analytical chemistry, effect

In concluding this part, three main points emerge from the summary of these results. First, the difficulty in achieving the preparation of these solids in a reproducible way can be solved only if a precision in the experimental parameters similar to that employed for physical or analytical chemistry measurements is used. This is a clear demonstration of the second point, which states that the textural parameters of the materials (porosity, specific surface area and surface composition) are under kinetic control. Temperature, solvent, catalyst, water/precursor ratio and concentration of reagents are the main parameters which, beside the nature of the organic subunit R, control the texture of the final material. The third point is the difficulty in rationalizing the effect of these parameters due to the numerous mechanisms involved in the sol-gel process and their interconnections. However, it must be kept in mind that all these parameters are also powerful tools that can be very useful for the development of further applications, because they allow one to tune the texture of the materials. 

There are two types of electrokinetic phenomena, namely those in which an electric potential is generated by the mechanical notion of a surface in a liquid and those in which a particle or liquid is caused to move by an electric potential. Classically there are four major effects, i.e., streaming potentials, sedimentation potentials, electrophoresis, and electroosmosis. (There are also several secondary effects that have been noted more recently such as acoustic potentials,K effect potentials, and U effect potentials.Each of the major effects has found a niche in physical chemistry, analytical chemistry, and chemical engineering. However, the application and understanding of electrokinetic phenomena in the biological sciences has been very spotty. 

Yakushiji, T., Sakai, K., Kikuchi, A., Aoyagi, T., Sakurai, Y, Okano, T. (1999). Effects of cross-linked structure on temperature-responsive hydrophobic interaction of poly(lV-isopropylacrylamide) hydrogel-modified surfaces with steroids. Analytical Chemistry, 71, 1125-1130. 

Systematic surface analytical studies on model or ideal systems. These are performed in order to understand the mechanisms and underlying physics and chemistry of various phenomena, such as the reactions promoted by additives, the effects of adsorption on friction and adhesion, and the degradation of a thin lubricant coating in a severe environment. 

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