February 29, 2008

U of C researchers net $3 million for study of catastrophic deformation

Catastrophic deformation may sound like the title of the latest Vin Diesel movie, but it is actually a complex and poorly understood physical phenomenon that explains occurrences like landslides and the buckling of steel beams. It has also caught the attention of a few dedicated University scientists.

Four U of C researchers—assistant physics professors Margaret Gardel and Wendy Zhang and physics professors Heinrich Jaeger and Sidney Nagel—are the main recipients of a $1.8-million grant from the W.M. Keck Foundation to launch a program to study catastrophic deformation.

The U of C has also pledged another $1.2 million for the project.

Catastrophic deformation occurs when small-scale structural changes in a physical system have rapid, severe, and wide-ranging effects. Examples abound in everyday life, from cell division inside our bodies to the splashing of a beer droplet on a barroom tabletop after an emphatic toast.

“It occurs when materials are pushed to their limits and undergo major changes in shape and/or properties,” Jaeger said in an e-mail interview.

Catastrophic deformation is a sub-class of what physicists call “far-from-equilibrium” behavior.

“Physics successfully describes phenomena near equilibrium, where quantities such as temperature or pressure characterize the behavior. However, many physical systems, indeed all of biology, occur far from equilibrium and cannot be understood by existing equilibrium approaches,” Jaeger said.

The team will use most of the money to fund a three-year research program into catastrophic deformation. But about $1 million will go toward developing new high-speed imaging instruments which are needed to study the massive changes on tiny timescales that characterize the phenomenon.

The new devices will include a microscope capable of providing three-dimensional images of cellular insides at a rate of 30 times per second, the same speed as a standard video camera. It will allow scientists to carefully observe the behavior of proteins and cellular skeletons under times of extreme stress, such as cell division.

“Currently, our understanding of cells as materials is limited. A better understanding of how cells sense, transmit, and exert mechanical forces would advance our understanding of basic cell physiology,” Gardel said.

For larger-scale deformations, like the splashing of a water droplet, researchers hope to procure a camera capable of snapping 500,000 images per second, over 16,000 times faster than a video camera.

The project could yield a better understanding of many physical occurrences. One of these is “memory,” which occurs in glassy materials such as window panes.

“One of the remarkable things that people see in glassy systems is that they often seem to have a memory,” Zhang said, in a University press release. “There’s a difference between how the material behaves if you simply cool it versus you cool it, reheat it, and cool it again. It seems to remember what you’ve done to it, and we’re not quite sure how.”

An improved understanding of catastrophic deformation will likely have applications for everything from the relatively trivial, such as how Silly Putty works, to the safety-critical, such as how landslides occur.

“Our vision with this research is to unearth the underlying general mechanisms, so that one can start building a framework to understand, predict and, eventually, control catastrophic deformations in a wide range of materials and situations,” Jaeger said.