The world’s smallest brush

University of Hawaii nanotechnology experts have invented the world’s smallest brush—a device boasting bristles a thousand times finer than a strand of human hair. Mehrdad Ghasemi-Nejhad, a professor of mechanical engineering at the university, said the brush may be used to sweep nano dust, paint small micro-tubes and clean pollutants in water. Nanotechnology involves the manufacture and manipulation of materials at the molecular or atomic level. At that scale, materials are measured in nanometers or billionths of a meter.

Ghasemi-Nejhad said the nanotechnology field could allow for the building of ever smaller chips that would reduce the size and weight of computers while increasing their speed and memory. Nanotechnology may also allow for low-cost, better-performing fuel cells that use hydrogen as clean fuel, he said. The tiny brush invention has earned the research team, which involves experts from Rensselaer Polytechnic Institute in Troy, New York, a spot in the 2007 Guinness Book of World Records. ’’We need to look at the needs in the nano-world, where machines and materials can be the size of atoms and molecules,’’ said UH doctoral student Vinod P Veedu. ’’As in the ’bigger’ world, there are messes to sweep, walls to paint, tubes to unclog and electronics to power. So our invention … demonstrates a way to make the tiniest of brushes to do these jobs.’’ Ghasemi-Nejhad founded the Hawaii Nanotechnology Laboratory in his UH department three years ago in part to train workers for a growing industry.

Case of the disappearing cookies

Tiny files called ‘‘cookies’’ are the lifeblood of online advertising. Left on visitors’ computers, they help Web sites track how many visitors they have, and how often they return—numbers crucial for determining the value of a site’s ad space. Skip to next paragraph So advertisers got worried in 2000 when privacy advocates began denouncing cookies. Soon after, antispyware programs started identifying cookies and offering to delete them. In 2004, 18 percent of people who knew what cookies were said they deleted them very frequently, according to a study by Revenue Science, which helps advertisers find online audiences. A survey in December 2005 reported a drop in that figure, to 8 percent. But more recent studies have been less cheerful for advertisers. A February report by JupiterResearch found that 41 percent of male Internet users and 25 percent of women manually deleted cookies at least once a week. Those figures would be even higher if they included people who used antispyware programs to delete cookies automatically.