Who is Bill Mallow? A prolific inventor, who worked on such diverse items as Liquid Paper, cat litter, M&M's, and anti-terrorist devices:

The polymer chemist spent nearly 40 years with Southwest Research Institute, where he worked on a variety of projects, from tiles for the space shuttle to improving the silicone rubber skin covering on the robotic dinosaurs in the Animal Kingdom at Walt Disney World in Orlando, Fla., and figuring out how to remove the peanut butter from the molds at M&M candy factories.

Liquid Paper, the correction fluid, was invented by San Antonio native Bette Nesmith Graham -- mother of Monkees star Michael Nesmith -- but Southwest Research helped refine the product at her request.

The cat litter, known as Scoop Away Clean, allows clumps of urine and solid waste to be removed daily, leaving the rest of the box fresh.

More recently, Mallow, who retired from Southwest Research in 1998 but remained a technical adviser, was working on a gel for the U.S. Marine Corps. The gel, called the Mobility Denial System, can be sprayed on everything from asphalt to windows of buildings.

Anyone who walks on it will fall, and vehicles will slip and slide. The gel, which could be deployed in 2003 or 2004, likely will be used to thwart enemy attacks on embassies and government buildings and for crowd control.