PAINT ON A HOT TIN ROOF
Painting roofs white is a simple way to cut the massive amount of energy used to run air-conditioning units in hot weather. But for some reason people just don鈥檛 like white roofs, says William Miller at Oak Ridge National Laboratory in Tennessee, so he and his colleagues have developed paint that will increase the reflectance of a house roof without painting it white.
White roofs usually remain close to the air temperature, whereas dark roofs can be as much as 40 掳C hotter on a sunny day, raising the temperature inside. To get around people鈥檚 aesthetic objections, Miller鈥檚 team developed paint with pigments made from a mixture of iron and chrome oxides. These absorb visible light and so look dark, but reflect infrared radiation so they stay much cooler. Lower air-conditioning bills could pay for the cost of applying the paint in just three years, Miller says.
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BY THE LIGHT OF A NANOTUBE
How many nanotechnologists does it take to change a light bulb? Jinquan Wei and colleagues from Tsinghua University in Beijing and Bingqing Wei of Louisiana State University in Baton Rouge have developed what is probably the world鈥檚 most expensive light bulb, with a filament made of pure carbon nanotubes.
The pair took a short length of the nanofibre filament and installed it in place of the tungsten filament in a 40-watt bulb. They report that the nanotube filament emits more light than the tungsten version at the same voltage. The bulb shone for more than 360 hours, despite being turned on and off over 5000 times (Applied Physics Letters, vol 84, p 4869). However, such bulbs would cost $200 each, and incandescent bulbs are rapidly giving way to LED-based lights that last up to 100,000 hours.
WATCH THAT PAYMENT
Who needs ID cards and cash, when a wristwatch will act as both? Users pass the watch in front of a door to enter a building, or in front of a cash till to pay for goods. The idea is to save people the hassle of fishing for cards and cash.
The Offica watch, developed by Casio of Japan, incorporates a payment chip originally developed by Sony for smart cards and 3G cellphones. It communicates via an encrypted short-range radio link and can either be 鈥渃harged鈥� with cash or used as a credit card in conjunction with a PIN code. It tells the time, too.
