Developments to Watch
PUTTING BRAINS IN PLANE WINGS
PLASTICS REINFORCED WITH CARBON FIBERS ARE LIGHT and durable--very desirable if you are building an aircraft wing or fuselage. But the virtues of these composites go beyond weight and strength, says Deborah Chung, professor of mechanical and aerospace engineering at the State University of New York at Buffalo. The composites could also someday be fabricated into giant arrays of solar cells, temperature sensors, and other semiconductor devices.
First, Chung says, the carbon fibers must be "doped" with chemicals that boost electrical conductivity. Then, by alternating layers of carbon fibers with layers of insulating material, engineers could create airplane wings or automobile body panels that would function as solar arrays, converting sunlight to electricity and storing it.
Chung's concept, presented at the International Symposium on Smart Structures and Materials in San Diego earlier this month, is a radical departure from conventional approaches, which embed tiny electronic or optical devices in the "smart" material. Here, says Chung, "we can use the structural materials themselves as the electronics." This approach would preserve the integrity of the materials and eliminate the need for expensive embedded chips.EDITED BY CATHERINE ARNST Neil GrossReturn to top
SHAKE, SHAKE, SHAKE YOUR FRUIT TREE
IT'S THE JERRY LEE LEWIS OF FRUIT PICKERS. An engineer with the Agriculture Dept., in partnership with a company that makes berry-picking equipment, has developed a machine that shakes the leaves of citrus trees until the fruit falls off--cutting harvesting costs by two-thirds.
Most citrus fruit is now picked by hand, a process that can cost $1.50 for each 90-pound box of fruit. Mechanical trunk shakers have been developed, but a chemical fruit loosener must be sprayed on the trees first, and no chemical has been approved for this use. So Agricultural Research Service engineer Donald L. Peterson, working with Blueberry Equipment Inc. of South Haven, Mich., has developed a leaf shaker. The machine looks something like a giant hairbrush with nylon bristles 12 feet long. The bristles reach into a tree's canopy and gently rotate and shake until the fruit falls.
Peterson tested the machine in Florida citrus groves over the past two seasons and says it harvested seven to nine trees per minute, up to 15 times faster than hand labor. And the cost was only 50 cents per 90-pound box. Turner Foods Corp., a subsidiary of Florida Power & Light Group that grows 18,000 acres of oranges, is now working with Blueberry Equipment to develop a commercial machine for next season. Could be the start of a whole lotta shakin' goin' on.EDITED BY CATHERINE ARNSTReturn to top
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IN SURGERY, A LITTLE DAB'LL GLUE YA
EVEN THE MOST SKILLED OF SURGEONS dread the leaks that can develop around incisions after patients have been stitched up with sutures or surgical staples. Focal Inc. in Lexington, Mass., is proposing to close them up with a dab of glue. Focal's synthetic surgical sealant expands and contracts with the tissue it adheres to and takes about a year for the body to absorb. The sealant, based on patented chemistry from the University of Texas at Austin, is a clear gel with the consistency of syrup. After putting in staples or sutures, surgeons drip the sealant along the incision, then harden it with a blast of special-wavelength light.
"If we can seal air leaks, the potential for infection goes way down, and patients won't have to stay in the hospital as long," says Dr. Larry R. Kaiser, a professor of surgery at the University of Pennsylvania, where clinical trials are being conducted. Focal's product has been approved for use in lung surgeries in Europe, and Johnson & Johnson has agreed to pay Focal $18 million for marketing rights to the sealant outside the U.S. The glue "will be expensive," says David M. Clapper, Focal's president and chief executive. "But most people spend $1,000 and up each day they are in the hospital."EDITED BY CATHERINE ARNST Paul C. JudgeReturn to top