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Over the course of my 40 year career at Stanford University, I have focused on the science of rheology, which refers to the study of the flow and deformation of soft, complex materials. Rheology enjoys a wide range of applications that includes the processing of polymer materials, suspensions, emulsions, surfactants, and foams. I also study interfacial fluid mechanical processes, particularly those involving evaporation mass transfer. It also is important to the characterization of biological materials, which represents a major portion of my current activities. I am an experimentalist and focus on the development of new rheometric and interfacial flow methods to measure the microstructural response of a variety of systems. Early in my career, I helped to develop the field of optical rheometry, the use of the interaction of light with flowing, deformed materials. That effort culminated in a successful book published by Oxford University Press: Optical Rheometry. In the late 1990s, I turned my attention to interfacial rheometry and the creation of interfacial rheometers that can report the viscoelastic properties of the molecular surfaces separating immiscible fluids. This resulted in two commercially successful instruments: the interfacial stress rheometer and the double wall ring rheometer. Because living systems are comprised of complex fluid interfaces (the cell membrane, the tear film, lung surfactants), there has been a natural evolution of my research program towards problems in human health. Central to this expansion of research direction has been the development of the live cell rheometer (LCR), which offers the means of measuring the viscoelastic response of layers of living cells. This has been applied to measurements of the adhesion of corneal epithelial cells to hydrogel contact lens materials and the strength of attachment of E coli onto bladder cells. Current work is investigating the ability of lubricin, a heavily glycosylated protein, to reduce the sliding friction between corneal epithelial cells and conjunctival cells. Work involving evaporation processes has largely been in pursuit of understanding the phenomenon of “dry eye” dysfunction and in the stabilization of foams. 

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