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This Microscope Can Poke At Atoms


Developments to Watch

THIS MICROSCOPE CAN POKE AT ATOMS

SINCE THEIR INVENTION A DECADE AGO AT IBM AND STANFORD UNIVERSITY, atomic force microscopes (AFMS) have produced startling images of exotic atomic landscapes. The scopes perform their magic by dragging a superfine needle across a sample of material. The needle bumps up and down as the atoms that form its tip are repelled by atoms on the sample. A computer then translates the movement into dazzling, multicolored topographic drawings.

Early AFMs used silicon tips. But in 1996, Nobel prize-winning chemist Richard E. Smalley replaced the silicon with a tough new carbon structure known as a "nanotube," which proved more flexible. Now, in the July 2 Nature, Harvard University chemistry professor Charles M. Lieber offers a glimpse of what nanotube tips will do for biology. Lieber and his team chemically modified a nanotube so that the AFM needle itself can perform chemical analyses as it travels over the sample. Since the tube is made of carbon, Lieber explains, "we can exploit well-developed organic reactions to attach various molecules that interact differently with the sample." That opens great possibilities. For example, it will be possible to explore features on a cell by attaching something to the nanotube that binds to a particular receptor. Or one could test whether a new drug molecule binds to a protein.

AFMs still can't deliver 3-D images of molecules. That requires x-ray crystallography, which constructs images out of patterns of x-rays diffracted from crystals. "But AFMs allow you to get functional information about the molecule you are studying," Lieber says.EDITED BY NEIL GROSSReturn to top

A TINY TURBINE TO POWER YOUR LAPTOP

SOMETIME AROUND 2000, SAY INVENTORS AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY'S gas-turbine lab, engines the size of shirt buttons could begin to replace 10- to 20-watt batteries in handheld computers, cell phones, and camcorders. Lab director Alan H. Epstein predicts that an engine-driven power pack could be made about 25% smaller than today's lithium batteries, and could run twice as long between rechargings.

Make that refuelings. The MIT invention resembles a jet engine, with a 2-mm-long combustion chamber, a 4-mm turbine wheel, and a tiny generator. The engine runs on butane and tanks come in different sizes. One the size of a laptop battery pack could deliver 20 hours of computer use.

So far, only the combustion chamber and the wheel have been tested. The generator won't strut its stuff until the fall. But over the next five years, Epstein believes, output of these tiny engines will soar to 100 watts. That's enough to satisfy the U.S. Army, MIT's sponsor, which wants a new power source for its global positioning system receivers, night-vision goggles, and other military gear.Nellie AndreevaReturn to top

TO ZAP SAND FLIES, TRY BUFFALO BREATH

FROM THE MANGROVE MARSHES AROUND BOYNTON BEACH, FLA., biting sand flies swarm into backyards and playgrounds, making life miserable for residents. University of Florida entomologist Jonathan Day feels the residents' pain--and has come up with a dandy fix.

Like all biting insects, sand flies--called moose flies and "no-see-ums" in the Northeast--track their hosts through plumes of carbon dioxide released by respiration. To protect school yards, Day is building fences--up to 1,500 long--fitted with traps that slowly release carbon dioxide and octenol, a chemical the bugs mistake for water-buffalo breath. The bugs swarm to the traps and get stuck in mineral oil that lines special mesh panels over the vents. In a recent one-day test, Day nabbed 200,000 sand flies in a single trap.

When the mineral oil is replaced with insecticide, Day says, the fence also works effectively against such blood-sucking nuisances as mosquitoes and deer flies. Day has applied for patents, and Air Liquide America Corp. of Houston plans to develop the product.EDITED BY NEIL GROSSReturn to top


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