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A microchain that closely resembles a bicycle chain except that each link could rest comfortably atop a human hair has been fabricated at the Department of Energy's Sandia National Laboratories. (The distance between chain link centers is 50 microns. The diameter of a human hair is approximately 70 microns.) Because a single microchain could rotate many drive shafts, the device would make it unnecessary to place multiple tiny microelectromechanical (MEMS) motors in close proximity. Usually, a separate driver powers each MEMS device. "All those drives take up a lot of real estate on chips," says Sandia technician Ed Vernon, who has received a patent for the silicon microchain. The microchain also makes it possible to drive a MEMS device from a motor situated at a distance, again saving considerable space on the MEMS-bearing chip. The microchain, says Ed, could be used to power microcamera shutters, as larger chains currently do in the macroworld. It could also be used in mechanical timing and decoding. The 50-link silicon microchain is designed to transmit power somewhat like the drive belt in a 19th-century sewing factory. There, a central engine shaft powered by steam turned drive belts to power distant work stations for example, sewing machines before the dawn of the age of electricity.
Vernon fabricated a microchain rather than a microbelt because although silicon belts are tough and flexible, they are spring-like and produce too much torque on gears not aligned in a straight line. Each chain link, on the other hand, is capable of plus-or-minus 52 degrees rotation with respect to the preceding link, without creating pressure on the support structure. The wide angle means MEMS designers can be relatively unconstrained in positioning multiple devices. The longest span unsupported by gears or bracing is 500 microns. A microchain tensioner is needed to accommodate longer spans. The multilevel surface-micromachined silicon device was constructed with the aid of Sandia's patented Summit IV and Summit V technology, which enables construction of complicated MEMS devices. Related Links Sandia National Laboratories SpaceDaily Search SpaceDaily Subscribe To SpaceDaily Express
Huntsville - Jan 15, 2002It's like a scene from the movie "Fantastic Voyage." A tiny vessel -- far smaller than a human cell -- tumbles through a patient's bloodstream, hunting down diseased cells and penetrating their membranes to deliver precise doses of medicines. |
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He said he had remained in touch with Pasko's lawyers, the ITAR-TASS news agency quoted him as saying.
Even if Federation Council lawyers decided that he is not entitled to act as Pasko's guarantor, he would write a letter of support for the journalist, Mironov said, describing the recent verdict as "unfair."
Only one of the 10 charges against Pasko was upheld, that of illegally attending a meeting of the Pacific Fleet's general staff and receiving information classified as secret, with allegedly the intention of passing it on to Japanese media.
Pasko was tried and acquitted on espionage charges in an earlier trial that ended in 1999, but found guilty of abuse of office for handing information about the alleged nuclear dumping to the Japanese media.
Both he and the prosecution appealed the decision, and the case was reopened last year.
He has already served nearly two years in jail while awaiting trial.
Earlier Thursday around 50 Pasko supporters picketed the headquarters of the security services, the FSB (former KGB), in Russia's far eastern city of Vladivostok where the reporter is being detained.
Police intervened and charged five protestors with disturbing the peace.
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