Importance of asphaltene characteristics, the characterization techniques, and the practical issues regarding industrial operations are briefly reviewed. The properties are viewed from macroscopic and microscopic length scales. Techniques used for characterizing such properties and their relevance to upstream and downstream operations are introduced. Finally, a conceptual approach for predicting asphaltene miscibility with lighter components is proposed.

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An overview of an important aspect of SANS research on charged colloidal suspensions is presented. These systems are characterized by pronounced interparticle correlations resulting from a strong and long-range double-layer interaction between macroions (i.e. the charged colloidal particles). Emphasis is laid on the use of simple statistical mechanical models, which are applicable in treating SANS data, that take into account the double-layer interaction. Examples are taken from work on dense protein solutions, ionic micellar solutions and protein-detergent complexes in aqueous solutions. Spherical and rod-like particles are considered. Polydispersity effects are taken into account whenever possible. In the case of rod-like systems, alignment by a shear gradient and the consequent analysis of two-dimensional SANS intensity distributions are briefly discussed.

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