-- After years of searching for affordable alternatives to the nasty, ozone-destroying chemicals used in refrigeration systems, engineers in Britain have found what is probably the cheapest and most benign candidate of all: air. In late March, two research groups at the University of Bristol unveiled a heating and cooling system that works by compressing air to create heat, then allowing the air to expand and cool. The same system keeps both hot water and cold water running, at temperatures ranging up to 176F or, for cold-water cooling, down to a chilly 43F.

-- The fairest mirror of them all--it reflects more light than any other mirror--has been developed by 3M. The new mirror is described in the Mar. 31 issue of Science. It is made from a stack of plastic films, including polyester, with each film contributing slightly different optical properties. 3M is already working on commercial applications. One is aimed at making the flat screens on laptop computers and handheld devices much brighter and easier to read.

-- Detroit's Big Three recently got together in a rare display of camaraderie to create an online trading exchange for the myriad parts and materials used by automobile manufacturers. Not to be outdone, four aerospace giants are doing the same. BAE Systems, Boeing, Lockheed Martin, and Raytheon will develop an independent Internet exchange to speed and simplify their purchases of parts and materials. Collectively, the four companies spend $71 billion a year on goods from more than 37,000 suppliers. If all goes well, both the auto and aerospace trading exchanges should be open for business before yearend.