Developments to Watch
Edited by Otis Port
Nano Peapods That Pack a Punch
Some molecules naturally go together like peas in a pod. Spherical clusters of carbon atoms called buckyballs, for example, are quite comfortable inside straw-shaped nanotubes, also composed of pure carbon. And these nano peapods may function as superfast transistors. That's the promise revealed by intricate measurements of nano peapods by a research team led by Ali Yazdani, a University of Illinois physicist.
Using a scanning tunneling microscope, the team mapped the movement of buckyballs and electron waves shown in this image inside the lilliputian peapods. They found that changing the location of the peas can transform the pod from a conductor into a semiconductor or an insulator. As a result, in future nanochips, carbon peapods may become a versatile component that can be tuned to play different roles.
Yazdani's team used peapods produced by David Luzzi's materials science group at the University of Pennsylvania, which first created these complex structures in 1998. Since then, several peapod varieties have been produced. And in Japan, scientists have stuffed metal atoms inside the pealike buckyballs in nanopods. "There's a whole gamut of things you can put inside" to modify a peapod's electrical properties, says Yazdani. Studying them all will keep him busy for years.
A Cuisinart for Recycling Plastics
Recycling the mountains of discarded computer cases, soda bottles, and other plastic waste makes ecological sense. But current recycling methods have serious flaws. Reusing a mix of different plastics typically involves a chemical glue, or "compatibilizer," to link otherwise incompatible polymers. Without good chemical bonds, the resulting material may be fragile. Yet compatibilizers "are expensive and don't always work," explains Viktor Williams, manager of global polymer recycling at DuPont in Geneva.
A new process--in essence, an industrial-scale Cuisinart--may solve these problems. Developed by Bernard Dubrulle d'Orhcel, chief technology officer of New York-based startup New Generation Plastic, the idea is to feed used plastics into a chamber with whirring blades. As the blades chop up the waste, the mechanical stress seems to break existing chemical bonds, paving the way for new ones to form, says Francesco Paolo La Mantia of Italy's University of Palermo, who has studied the process. In fact, tests show that the resulting material can have better properties than any of the original ingredients--and the process is far cheaper than current recycling methods. Says Dupont's Williams: "It is a real breakthrough." He also suggests that the technology could prove valuable in making new and better types of "virgin" plastics.
New Generation Plastic has created about 40 tons of recycled material in a French research lab using the new technique. It expects to begin building a full-scale plant in the Corrèze region of France this spring.
By John Carey
Turning a Bionic Eye on Retinitis
Patients with retinitis pigmentosa progressively lose their sight because of the death of specialized cells, called rods and cones, at the back of the eye. Normally these cells respond to light by creating electrical impulses that the brain processes into images. Existing therapies for retinitis pigmentosa slow the deterioration of the rods and cones, but they don't arrest the disease.
Now, scientists at the University of Houston and a NASA-funded laboratory hope it may be possible to restore vision with a bionic eye. Alex Ignatiev and Dr. Charles Garcia head a team working on light-sensitive ceramic detectors that appear to function like cone cells. Hundreds of thousands of the sensors are packed together on a plastic film and implanted in the eye. Studies in rabbits indicate that the device is safe and stable, and human tests could begin in 2003. Because the signals generated by the ceramic detectors are different from those produced naturally, Garcia cautions that the artificial retina may not restore normal vision.
By Ellen Licking
Battery Power: Where the Latte Meets the Lithium
In today's mobile world, lithiumion batteries are the power source of choice for laptops, digital cameras, and other portable gizmos. However, these light and long-lasting batteries have a big drawback: price. They cost at least 30% more than other power packs. But Sony, which launched the first lithium-ion batteries in 1990, is working on a surprising way to cut their cost.
Here's the challenge: Lithium is a highly reactive metal and must be stabilized by encapsulating the molecules in carbon--using an expensive form of graphite derived from oil. Sony has found an alternative in a most unlikely place: coffee makers. In 1994, Shinichiro Yamada, a researcher in Sony's central labs, decided on a whim to see if used coffee grounds, which are largely carbon, could store lithium. Sure enough, they could.
Sony has now developed a process to harvest the carbon in coffee grounds. Although tests indicate that batteries made with coffee carbon might pack even more power than those in use today, Sony hasn't decided to go commercial yet. But if it does, the cost of carbon could be trimmed by 50%. That's because there's no shortage of the raw material in Japan, where coffee-service companies dispose of 270,000 tons of coffee grounds a year.
By Irene M. Kunii
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Copyright 2002 , by The McGraw-Hill Companies Inc. All rights reserved.
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