New for the nanotechnology toolbox. Mi Hong, a CAS research associate professor of physics, and her colleagues at the Photonics Center are developing a new tool to help scientists see biomolecules only a few billionths of a meter in size.

The new technology, known as SNIM (for scanning near-field infrared microscopy), combines infrared spectroscopy with spatial imaging resolution below the diffraction limit to produce clear images of biomolecules - the carbohydrates, lipids, nucleic acids, and proteins that make up living organisms - without destroying them.

Since most biomolecules are colorless when viewed in the visible spectrum, they are generally stained with radioactive or fluorescent labels. Choosing the correct stain necessitates an educated guess about what the sample contains. Also, because the labels are toxic, they ultimately destroy the molecules they are designed to study. SNIM is based on a tunable infrared laser with a pulse width of about 100 femtoseconds that can be tuned to reveal the unique "fingerprint region" that identifies the sample. Because the system uses the normal vibrational mode of the molecule, the molecules are not destroyed in the process.

Hong is collaborating with Kris Peterson of Southwest Sciences, Santa Fe, N.M., on developing the new time-resolved SNIM. Applications for this technology include examining the effects of anesthetics on neurons and, by identifying increased concentrations of certain molecules, in cancer screening. In the long run, by using SNIM and other nanotechnology tools, scientists may someday be able to repair damaged biomolecules to cure disease at the molecular level.

Screeching to a halt. A recent article in the Boston Globe points out that brakes don't stop cars, tires do. Brakes stop the car's wheels from spinning - and all too often with a loud screech. Soon, however, drivers and pedestrians alike may breathe a sigh of relief, thanks in part to research by J. Gregory McDaniel, an ENG assistant professor of engineering. McDaniel recently won the Ralph R. Teetor award from the Society of Automotive Engineers for his research on brake squeal.

McDaniel considers brakes to be an acoustical system. "Brakes are amazingly efficient radiators of sound," he says. "My guess is that brakes radiate sound better than violins." His research reveals that the round rotors used in brakes produce curved vibrational waves that spiral out, closely matching the vibrational patterns of acoustic wave scales in air.

The methodology he developed used a stationary brake system that he demonstrated to be the equivalent of an operating brake system - eliminating the difficulties of inducing squeal in the laboratory and of measuring velocities on a moving surface. Automobile manufacturers who use this technology will be able to pinpoint problem areas and redesign rotors to eliminate squeal. They will also be eliminating costs ($ 100 million per year in North America) incurred for checking cars under warranty with noisy, but effective, brakes.

The Ford Motor Company supported this research.