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Dentures That'll Grow on You


There may one day be an alternative to false teeth. Scientists at Forsyth Dental Institute in Boston report that they were able to plant individual tooth cells in laboratory animals and grow them into viable teeth. While still in a preliminary stage, the research could lead to a human tooth substitute grown from a patient's own cells.

The development, described in the Journal of Dental Research, is part of a broad effort by scientists to cultivate human tissues from a few living cells. The For-syth team, led by Dr. Joseph P. Vacanti, isolated the cells of immature molar tooth buds from young pigs, a good source of cells that are similar to those of humans. Each cell was placed in its own tiny, biodegradable scaffold, and these were then implanted near the intestines of rats, a suitable environment for growing cells. After 20 to 30 weeks, crown-like structures developed containing all the layers of a normal tooth, including enamel.

Vacanti says the experiment "points the way for biological repair in [human] dental disease"--an application with great potential, since U.S. adults after age 50 lose an average of 12 teeth, including wisdom teeth. The work also suggests the existence of dental stem cells that could be used in many areas of tooth repair, Vacanti says. Cycling is a sport of long races won by tiny margins. In July, Lance Armstrong took the three-week Tour de France by just seven minutes, a scant 0.15% faster than the runner-up. Indeed, Armstrong has dominated the past four tours in part by shaving seconds using just about every high-tech trick permitted by the International Cycling Union (ICU), from aero-helmets to carbon fiber wheels, no matter how tiny the benefit.

That's why a new pedal crank design could have big implications. According to a study in the Journal of Biomechanics by a research team led by Paola Zamparo, a PhD student at Italy's University of Udine, the new crank yielded a 2% increase in metabolic efficiency when tested on amateur cyclists. Such a boost would have stretched Armstrong's margin of victory to over an hour. The prototype's key is its "sun-wheel" design. This allows the pedal's position to vary in relation to the crank's pivot point, effectively lengthening the crank arm--and boosting power--on the down stroke. It also shortens the crank arm on the up stroke, thereby cutting resistance.

Before the prototype shows up on the tour, it will need ICU approval and will have to show similar benefits for the pros, who control their pedal power far more efficiently. Translucent, light-as-air substances known as aerogels may finally find their way out of the lab. To be useful, aerogels must remain firm in different environments--a hurdle that most such materials have not cleared. Now, researchers at the University of Missouri at Rolla have discovered how to make a composite aerogel strong enough to stop a bullet and capable of retaining its shape even when saturated.

Nicholas Leventis, a Missouri chemistry professor who led the aerogel research team, has found that by weaving nanosize plastic particles together with silica specks, he can make aerogels that are ethereally light but 100 times stronger than past versions. Using Leventis' recipe, the stuff still takes days to produce. On the other hand, it's dirt-cheap and can be molded into nearly any shape. The scientist believes his aerogel could be fashioned into bullet-proof vests or used as a porous medium to store jet fuel safely. -- Chemistry textbooks describe glass as amorphous. But James D. Martin, a chemist at North Carolina State University, reports in the Sept. 26 Nature that the arrangement of molecules in glass, and even water, has a structure that's not random. This means glass could be engineered to embody optical and electronic properties never before thought possible. Martin has already done so with liquids. Adding tiny impurities can change their properties, just as traces of boron transform silicon from an insulator into a semiconductor.

-- Early last spring, Artera Group Inc. unveiled technology that enables ordinary modems to achieve broadband speeds. Initially offered to small business, the service now comes in a home version. It boosts a 56-kilobit-per-second modem's speed nearly sixfold and costs just $9.95 a month. Download software and tech specs at www.arteragroup.com.

-- Artificial muscles and implantable drug pumps are two potential uses for a new, all-organic composite developed at Penn State University. A team led by electrical engineer Qiming Zhang found that a combination of an uncommon polymer matrix plus an organic semiconductor creates a material that moves like muscle tissue when stimulated by electrical signals. Compared with earlier so-called electroactive polymers, the electrical energy needed to make this one flex is slashed by 90%.


Steve Ballmer, Power Forward
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