Research Roundup

$1.26 Million to Study Microfluidic Systems | $2.84 Million to Improve Reliability of Computers | National Technology Lab for Adult Education | "Fuzzy" Molecules Assemble into Distinct Lattices | Mild Head Injury Increases Brain's Vulnerability

$1.26 Million to Study Microfluidic Systems

Researchers at Penn have received a three-year, $1.26 million grant, part of a push to develop minute, fluid-based systems that could be used to safely detect minuscule quantities of airborne pathogens, analyze blood in real time and inconspicuously monitor the safety of food and water.

The grant, to a Penn team led by Dr. Haim H. Bau, professor of mechanical engineering and applied mechanics, comes from the Defense Advanced Research Projects Administration, which is interested in furthering the development of such microfluidic devices. Microfluidic systems are intriguing to the military and others because they would allow for real-time, inexpensive testing of samples, in some cases continuously and remotely, without a need for skilled personnel.

Dr. Bau and Penn colleagues Dr. Irwin M. Chaiken, research professor of medicine and rheumatology, and Dr. Howard H. Hu, associate professor of mechanical engineering and applied mechanics, will model the transport of liquids, particles, macromolecules and cells in microconduits and study their effect on biological interactions. The fluids and particles will be driven and stirred by electrical and magnetic forces.

In order to test their ideas, the team will fabricate prototypes with low-temperature co-fired ceramic tapes. In a prior DARPA-supported effort, a Penn team demonstrated the applicability of the ceramic tape technology for the fabrication of microfluidic systems.

"These tapes allow one to fabricate devices and systems rapidly and inexpensively," Dr. Bau said. "We can literally go from a design to a prototype in a matter of days."

$2.84 Million to Improve Reliability of Computers

Computer scientists at Penn and other institutions have received a $2.84 million grant to boost the dependability of the specialized minicomputers embedded in electronic devices from toasters to passenger jets.

The three-year award, from the U.S. Department of Defense's Army

Research Office, brings external funding awarded to Penn's embedded systems research group within the last 18 months to more than $6 million.

"These tiny embedded computers can literally make the difference between life and death, so their reliability is crucial," said Dr. Lee, principal investigator and professor of computer and information science at Penn. "Even though they're small, these computers are growing more complex, meaning the number of problems that can develop in them is also growing."

Dr. Lee and his peers will examine ways to engineer reliability and reusability into embedded computers' software during the earliest stages of design. Among their goals: developing an integrated approach to development of reliable embedded systems that takes into account real-time issues and resource constraints the system will face, such as energy consumption, memory size and weight of the final product.

Embedded computers are ubiquitous, found in products ranging from dishwashers to automobile transmissions to cellular phones. They underpin much of modern medicine; equipment like heart-lung machines, infusion pumps, defibrillators, dialysis machines and mammography machines are all rife with embedded systems. "Embedded systems are becoming increasingly networked, meaning the failure of one can cause many others to fail," Dr. Lee said.

Lee's Penn colleagues on the ARO grant include Dr. Rajeev S. Alur, Dr. Carl A. Gunter and Dr. Sampath Kannan, each a professor of computer and information science, and Dr. Oleg Sokolsky, research assistant professor of computer and information science. Others on the project include Dr. Robert P. Cook at Georgia Southern, Dr. Elsa Gunter at NJIT and Dr. Kang G. Shin at Michigan.

National Technology Lab for Adult Education

Educational researchers at the national Center on Adult Literacy at Penn have been awarded a three-year, $2.4 million grant from the U.S. Department of Education to foster the use of technology, including distance learning, the Internet and CDs, in adult education and literacy programs nationwide.

The goal of the project, TECH.21, is to make it possible for program directors and practitioners to know what is available and make the best choices for their students. Adult education and literacy teachers and learners from nine sites across the country will experiment with educational technologies designed to improve learning. The principle site of the National Technology Laboratory will be at Penn.

NCAL's partners in this technology initiative include the Sacramento County, Office of Education/Outreach and Technical Assistance Network, the Public Broadcasting Service and the National Adult Education Professional Development Consortium.

"Fuzzy" Molecules Assemble into Distinct Lattices

Physicists at Penn have determined that adding a "fuzz" of chemical chains to colloidal molecules can lead them to form a predictable array of lattices. The entropy-driven phenomenon represents a way in which the power of entropy might be harnessed by scientists for constructive purposes.

The finding, in which researchers led by Penn physicist Dr. Randall D. Kamien, examined the effects of a halo of polymer limbs on otherwise spherical molecules suspended in liquid, is the cover story in the current issue of the Journal of Physical Chemistry B.

Dr. Kamien's work adds new evidence that entropy is far richer than the gloomy drive toward universal disorder it was once thought to be and suggests it could become a player in the world of self-assembling molecules. Entropy's knack for driving fuzzy molecules into distinct lattices offers scientists the promise of new materials designed rationally rather than through trial and error.

"Predicting the symmetry of the lattice formed by an organic compound is one of the oldest dreams of synthetic chemists," said Dr. Kamien, an associate professor of physics and astronomy at Penn. "By providing an empirical connection between molecular structure and macroscopic organization, our result will allow chemists to design new materials from the top down."

Dr. Kamien's theoretical work focused on colloids, which feature particles suspended in liquid. Colloids are all around us, from milk to microreactors, from pie filling to paint. Crystals formed from colloids form the basis for a new class of functional materials for use in optical switches, chemical microreactors and molecular sieves; the new finding suggests the possibility of creating "designer molecules" to speed this process along.

"The old view was that the densest packing wins," Dr. Kamien said. "Our work shows it's not that simple, especially as molecules grow less dense."

The molecules in the colloids Dr. Kamien studied were characterized by a relatively dense core surrounded by a corona of hundreds of spindly chemical arms. When virtually none of the fuzz was present, the particles did indeed organize themselves into a face-centered cubic array.

But as the fuzz grows in length, to the point that the molecules were almost all fluff with a very small core, they would form different arrays of lattices that could be mapped with precise phase diagrams. At stages where the fuzz was of an intermediate length, Dr. Kamien's theoretical work predicts a mixture of face-centered cubic and other lattices corresponding to the length of the fuzz, a prediction consistent with experimental findings by Penn chemist Dr. Virgil Percec and others.

Dr. Kamien's co-author on the Journal of Physical Chemistry B paper is Dr. Primoz Ziherl, Institut Jozef Stefan in Ljubljana, Slovenia. Dr. Kamien and Dr. Ziherl's work was supported by the NSF, the American Chemical Society's Petroleum Research Fund, the Alfred P. Sloan Foundation and Penn alumnus Larry Bernstein.

Mild Head Injury Increases Brain's Vulnerability

They may want to "shake it off" and get back into the game. But a single head injury--even a mild one--can put athletes at risk for further traumatic brain injuries. According to researchers at the School of Medicine the brain has an increased vulnerability to severe, perhaps permanent, injury for at least 24 hours following a concussion.

Their results, published in the latest issue of the Journal of Neurosurgery, have serious implications for victims of accidents and abuse, as well as amateur and professional athletes. The researchers believe their work provides a new model for looking at repetitive head injuries (RHI). The prospect that athletes may be returning to the field too soon after a head injury is alarming, say the researchers. The research was funded by NFL Charities.

"If you look a the guidelines for mild head injuries in athletes--from high school to the pros--you'll see that they are written with little hard scientific date," said Dr. Tracy K. McIntosh, the Robert A. Groff Professor in the Department of Neurosurgery and director of the Penn Head Injury Center. "Our findings represent the first real attempt to look a the science behind bead injuries--and we were startled to see how permanent the damage can be."

There is already a growing body of data that suggests that those that suffer RHIs in sports may be at greater risk for neurodegenerative diseases later in life. In fact, the damage to the brain found in victims of Dementia Pugilistica, or "Punch Drunk Syndrome," closely resembles that of Alzheimer's patients.

Although they do not know the exact mechanism that leads to damage after repetitive head injuries, Dr. McIntosh and his colleagues are interested in one brain cell protein that has also been implicated in contributing to Alzheimer's accumulations of the beta-amyloid precursor protein (B-APP) was found in great quantities in the neurons of mice that received RHIs, accompanied by an increase in the amount of dead or dying neurons. They hypothesize that the damage from injury causes B-APPs to gradually accumulate in the cytoskeleton of neurons, which serves as the support structure for the cell as well as the roadway by which nutrients travel throughout the cell. This roadblock slowly chokes off the cell and eventually leads to its death.

According to Dr. McIntosh, traumatic brain injury (TBI) is a "silent epidemic" in our society. Each year, an estimated two million cases of TBI occur in the U.S., with approximately 500,000 cases serious enough to require hospitalization.

$1.26 Million to Study Microfluidic Systems | $2.84 Million to Improve Reliability of Computers | National Technology Lab for Adult Education | "Fuzzy" Molecules Assemble into Distinct Lattices | Mild Head Injury Increases Brain's Vulnerability

Almanac, Vol. 48, No. 15, December 11, 2001

ISSUE HIGHLIGHTS:

Tuesday,
December 11, 2001
Volume 48 Number 15
www.upenn.edu/almanac/