SMALL SCALES
A nanoscale weighing machine can now measure the mass of a single virus. The device may some day be used to detect, or even identify, small organisms. Harold Craighead and his group at Cornell University in Ithaca, New York, built microscopic cantilevers, just 4 micrometres long and 500 nanometres wide, out of silicon and silicon nitride. The cantilevers vibrate at a known frequency, but with any extra mass that frequency will change. The researchers monitor the frequency by shining a laser on the device and watching the reflection change.
The team had already measured the mass of a single E. coli bacterium, which weighed in at 665 femtograms. To detect viruses, they constructed even smaller cantilevers and enclosed the device in a vacuum (Journal of Applied Physics, vol 95, p 3694). A virus can have a mass of just 10 attograms 鈥� a hundred-millionth of a nanogram.
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CHARGE!
A battery that can be recharged in 30 seconds has been developed by NEC in Japan. It usually takes at least an hour to recharge the cells found in mobile phones and laptops. NEC says its 鈥渙rganic-radical鈥� batteries will provide the same performance as a conventional cell, providing enough power to operate an MP3 player for 80 hours. The company expects the first commercial application to be as an emergency power source for laptops. It expects the batteries to go on sale in two to three years.
ELEGANT NANO VASE
Glass-blowing is no longer the preserve of artists 鈥� nanotechnologists are at it too. A carbon nanotube can be blown into a bulb in the same way that a tube of glass is turned into a vase.
Zhenping Zhu of the Institute of Coal Chemistry in Taiyuan, China, and his colleagues developed a new way to synthesise carbon nanotubes 鈥� rolls of carbon atoms useful in electronics 鈥� using explosives (New 杏吧原创, 23 November 2002, p 19). A side effect was the expansion of the tubes into ball shapes when hot gases became trapped inside.
Pictures of the strange structures, taken with an electron microscope, are published in Advanced Materials (vol 16, p 443). Some are flask-shaped with a nanotube neck. They could be used as miniature containers or reaction vessels, the researchers suggest.
