A particle in a complex fluid -- a synthetic thickener in pancake syrup, for instance -- acts differently from the same particle in a simpler fluid, such as water. UC Davis graduate students have uncovered new information on those quirks that could help solve problems ranging from unwanted fiber clumps in plastics manufacturing to improved timed-release medications. At last week's annual meeting of the American Institute of Chemical Engineers in Los Angeles, doctoral students working under the direction of associate professors Stephanie Dungan and Ronald Phillips detailed their findings. Housam Binous described a computer model he created that predicts the actions of a viscoelastic fluid -- one that is resistant to flow and can return to its initial state after being deformed, as cake batter does after stirring. In his model, Binous portrayed the fluid as a suspension of tens of thousands of dumbbells made of two beads connected by a spring. When he released virtual particles into this computer suspension, the model produced events just like those seen in real experiments. Such a model should be useful for scientists designing synthetic materials, Phillips says. Stuart Nolan studied how surfactant micelles -- soaplike particles that can deliver drugs, flavors or preservatives -- behaved in water and in a gel, another complex fluid. Round micelles behaved consistently in both media, but cylindrical micelles shrank in the gel, making them diffuse more rapidly. That information could be helpful to designers of cosmetics and pharmaceuticals.