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Plastic Fiber That's Built For Speed


Developments to Watch

Plastic Fiber That's Built for Speed

When it comes to high-speed digital networks, nothing beats glass fiber for transmitting large volumes of voice and data. Converted to pulses of light, information courses instantly through miles of long-distance trunk lines. As a wiring material for home networks, however, superpure glass is both fragile and expensive. New plastic fibers offer advantages on both fronts, but transmission speeds have been limited to about 1 gigabit per second (Gbps)--many times slower than glass.

Japan's Asahi Glass Co., in collaboration with Keio University Professor Yasuhiro Koike, has developed a plastic fiber made of a transparent fluorine-based polymer, which promises a tenfold speed improvement over other plastic fibers. What's more, the development team claims that the new fiber can send light signals farther than either glass or other types of plastic before distortions start to creep in. "We believe it will be the best material for local-area networks," says Asahi's spokesman Hiroshi Mori.

The Asahi Glass project began in 1993, when Koike approached the company with the idea of creating an optical fiber out of a fluorine-based plastic that Asahi had created. Thanks to years of incremental improvements, Asahi can now send light signals as far as 500 meters at more than 1 Gbps.

Asahi plans to start marketing the new plastic fiber in June. Initially, it will be priced at the same level as glass fiber, but Asahi hopes to bring costs down quickly. With fiber-optic networks spreading in Japan, Asahi expects sales of $100 million in five years.Edited by Neil Gross; By Irene KuniiReturn to top

Don't Worry If This Dome Collapses

Your children may have played with Chuck Hoberman's toys. Someday, they may also sit beneath his domes. The New York inventor and his wife, Carolyn, are known for their colorful, collapsible plastic toys called Hoberman spheres. But they also build giant works of art and soon hope to tackle functional architecture. This summer, Expo 2000 in Hanover, Germany, will feature a 15-foot-tall Hoberman dome commissioned by Germany's Dresdner Bank. Perched atop 16-foot pillars, the dome will expand and shrink, almost like one of the plastic toys.

Someday, says Hoberman, the retractable aluminum-and-steel struts could support a lightweight, flexible skin that could be closed against the elements and opened to the sky in fair weather. "Spaces can be transformed in response to changing needs, which may be climatic, artistic, or simply entertaining," says the inventor. The dome will stay in Hanover for six months before moving permanently to Dresden.Edited by Neil GrossReturn to top

Combing DNA Strands for Defects

Coding errors in DNA strands can cause devastating genetic diseases. Such defects, which have been implicated in cystic fibrosis, sickle cell anemia, and many other diseases, are often difficult to detect. But scientists at IBM's Zurich Lab and the University of Basel hope to remedy that with a minuscule molecular device that would literally comb through tangles of DNA to locate defects.

The prototype IBM comb has delicate silicon teeth, each one measuring less than one-fiftieth the diameter of a strand of human hair. As described in the Apr. 14 issue of Science, one side of each tooth is coated with biomolecules that are attracted to specific nucleotide sequences on the DNA strand. When the coating encounters its DNA match, the individual teeth bend.

As the comb passes over the nucleic acid, researchers bounce lasers off the teeth to measure precisely how much each tooth moves. Certain movements then can be correlated with the presence or absence of tiny defects known as single-base mismatches.

Christoph Gerber, a scientist at IBM'S Zurich Lab, says that these tiny molecular combs might one day be packaged onto chips that would perform a variety of DNA tests more cheaply and effectively than existing DNA chips.Edited by Neil GrossReturn to top


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