Vito A. DePalma

Human fibrinogen adsorption onto surface-energy-controlled substrata

Abstract It has generally been observed that platelets do not attach to non-physiologic materials until about a minute after first exposure of foreign surfaces to blood. During that period, spontaneously adsorbing plasma protein layers, dominated by fibrinogen, deposit as conditioning films. This study addressed the properties of such conditioning films of purified human fibrinogen adsorbed to well-characterized substrata under both static and flow conditions. The results suggest that the adsorbed film was more loosely organized and perhaps in a more native configuration on low-energy substrata than on extremely low, medium, or high-energy substrata. The results support the hypothesis that there is a particular range of surface properties for biomaterials that correlates with the least perturbation of protein conformation in the adsorbed state, accounting for the better blood compatibility of such materials.

Universal gelling agent for the control of hazardous liquid spills

Abstract Under contract to the U.S. Environmental Protection Agency, Calspan Corporation developed methods to treat, control and monitor spilled hazardous materials. One of the most successful spill countermeasures applied was a dry, finely-granulated blend which would, within seconds after contact with spilled liquids, begin their transformation into tough, immobile gels which could be easily controlled and removed. This blend is a “universal gelling agent” in the sense that it can immobilize essentially all hazardous liquid spills without foreknowledge of the liquid composition. The blend contains powdered polymeric components optimized separately for interaction with aqueous liquids, chlorinated organics, alcohols, and nonpolar hydrocarbons. It also contains a fumed silica fluidizer, which provides ease of field application and imparts longer term stiffening of all gels formed. The “universal gelling agent” has been demonstrated to be effective on a variety of medium scale (55-gallon drum) spills on both land and water. For special uses, such as organophosphorus pesticide spill control, the blend can be reformulated to include de-toxifying (oxidizing, hydrolytic) ingredients as well.