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What's Needed for Teensy-Weensy Cell Phones


The chips inside cell phones keep getting smaller. But the phones' size seems to be frozen, especially for multimode models that work on different continents. The reason is simple, says Clark T.C. Nguyen, an electrical engineer at the University of Michigan. Radio-frequency (RF) filters still hog a lot of space on the phones' circuit boards.

These quartz and ceramic filters grab a specific frequency for your phone calls while blocking all the others. They can vary in size, but often measure about 2 by 2 centimeters--and you need several to receive and transmit. Plus, if your phone is designed to function in different countries, it requires multiple sets for each format.

Nguyen says that he can shrink the filters way down by using the same fabrication technology that turns out tiny airbag sensors in automobiles. The technology carves mechanical devices in silicon gizmos known as microelectromechanical systems (MEMS). "It's the IC [integrated circuit] revolution for mechanical stuff," says Nguyen, who was once part of a team of scientists that road-mapped future communications for NASA. Now he has formed a startup, Discera Inc., to make MEMS filters for cell phones.

To be sure, there will be some challenges, including the vacuum packaging required for such devices. But ultimately, says Nguyen, the MEMS parts could be integrated with the silicon circuitry. Once that is achieved, cell phones will shrivel to the size of watches, or even finger rings. Tatiana Makarova wanted to create a superconductor by tightly packing tiny carbon buckyballs into sheets that resemble bubble wrap. Instead, the Russian physicist stumbled on what could be a far more important discovery: a carbon magnet that works at room temperature. Until now, metal-free molecular magnets were mainly cryogenic curiosities, working only at a frigid -255C or below. But Makarova's nano bubbles stay magnetic all the way up to 200C, according to her report in the Oct. 18 issue of Nature.

Buckyballs are about one-millionth as fat as a human hair. If they can be applied as magnetic coatings, the amount of data that could be stored on hard drives might jump 5,000-fold, to 30 trillion bits per square centimeter. That's enough to hold roughly 10,000 encyclopedias.

Why the bubble-wrap configuration retains its magnetic properties at room temperature is a mystery, says Makarova, who is based at Ioffe Physico-Technical Institute in St. Petersburg but is working on nano bubble magnetism with a team from Sweden's Umea University. The group hopes that understanding the basic physics will lead to advances in electrical and electronic devices. Proteins are the basic structures of life: What they do in our bodies depends on their shape. If a string of amino acids folds one way, it may become an essential enzyme. A different shape, however, may form a protein associated with a genetic disease such as cystic fibrosis.

Researchers around the world are struggling to understand the dynamics of protein folding because it's the key to designing new wonder drugs. Trouble is, the folding happens too quickly to study the process in detail, and the dozens of amino acids in a protein chain can fold into so many complex three-dimensional shapes that even supercomputers strain to simulate all the possibilities that might prove valuable. To narrow the problem, researchers assume each amino acid prefers to be surrounded by certain other molecules, then they program a computer to search for the best overall "fit."

Now, there's a more accurate shortcut. A team at Pennsylvania State University, led by physicist Jayanth R. Banavar, has developed a so-called neural network system that does a better job of predicting protein structure by mimicking the brain's circuitry. When Banavar's system was tested--by feeding it data on 213 amino-acid strings--the neural network correctly predicted the shape of 190 of the resulting proteins. As Banavar's team will report in an upcoming issue of Proceedings of the National Academy of Sciences, existing software tools accurately predicted only 137 of the final protein structures. -- Even when Halloween rolls around, Thomas C. Meierding has no fear of graveyards. In fact, cemeteries are one of his favorite haunts. The University of Delaware geomorphologist studies tombstones for clues about environmental trends over the centuries. By measuring the difference between tops and bottoms of stone markers, he can judge how the stone has been eroded by air pollution and can compare urban vs. rural regions and different slices of history. Meierding has visited 700 cemeteries and compiled data on 15,000 tombstones. It shows just how corrosive urban air was in the 19th century, when factories spewed out black smoke from coal-burning furnaces--and how dramatically the destruction has slowed in modern times.

-- Could this be the ultimate car bumper? Surajit Sen, a University at Buffalo physicist, has designed a small megaphone-shaped structure filled with progressively smaller spheres. Energy that enters the wide end--the impact force from a traffic accident, for example--gets repeatedly diminished as it travels from sphere to sphere, exiting at no more than 5% of its original force. With lots of sufficiently long cones, almost any amount of energy can be absorbed, says Sen. The concept could even help bridges and buildings withstand earthquakes.


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