Skip to main content

This Years Julian Smith Lecture

in this section

2014 Julian C. Smith Lecturer: John F. Brady of Caltech

John F. Brady will deliver the 2014 Julian C. Smith Lecture Series
Monday, April 14
The Micromechanics of Colloidal Dispersions

It's morning. You pour cereal into your bowl. Shake the orange juice and fill your glass. And pour milk over your cereal. Why did you shake the orange juice and not the milk? Why do you pour cereal? These are just some everyday examples of complex fluids- materials that often behave like water or air, but just as often display quite different behavior. Many soft materials, or complex fluids, are in the form of particles dispersed in a host liquid or gas, and it is the particle-level interactions that give rise to interesting macroscopic phenomena, such as shear thinning and thickening, viscoelasticity and structure formation. This talk will discuss the micromechanics of particulate dispersions and how the interplay of colloidal, Brownian and hydroynamic forces set the material's microstructure and determine its macroscopic properties. Examples of hard sphere systems ranging in size from a few nanometers, via computer simulation and the results compared with theory and experiment. So why did you shake the orange juice and not the milk?

Tuesday, April 15
Chemical Swimming and Active Matter

One of the distiguishing features of many living systems is their ability to move, to self-propel, to be active. Through their motion, either voluntarily or involuntarily, living systems are able to self-assemble: birds flock, fish school, bacteria swarm, etc. But such behavior is not limited to living systems. Recent advances in colloid chemistry have led to the development of synthetic, nonliving particles that are able to undergo autonomous motion by converting chemical energy into mechanical motion and work- chemical swimming. This swimming or intrinsic activity imparts new behaviors to active matter that distinguish it from equilibrium condensed matter systems. For example, active matter generates its own internal stress, which can drive it far from equilibrium and free it from conventional thermodynamic constraints, and by doing so active matter can control and direct its own behavior and that of its surroundings. In this talk I will discuss our recent work on chemical swimmers and on the origin of a new source for stress that is responsible for self-assembly and pattern formation in active matter.

John F. Brady is the Chevron Professor of Chemical Engineering and Professor of Mechanical Engineering at the California Institute of Technology. He received his BS in chemical engineering from the University of Pennsylvania in 1975, which was followed by a year at Cambridge University as a Churchill Scholar. He received both an MS and PhD in chemical engineering from Stanford University, the latter in 1981. Following a postdoctoral year in Paris at ESPCI, he joined the Chemical Engineering department at MIT. Dr. Brady moved to Caltech in 1985. 

Dr. Brady has been recognized for his work by several awards, including a Presidential Young Investigator Award, the Professional Progress Award of the American Institute of Chemical Engineers, the Bingham Medal of the Society of Rheology and the Fluid Dynamics Prize of the American Institute of Physics. Dr. Brady served as an associate editor of the Journal of Fluid Mechanics and editor of the Journal of Rheology. He is a fellow of the American Physical Society and member of the National Academy of Engineering.