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See Inside June 2008

Updates: Whatever Happened to Self-Cleaning Clothes?

Self-Cleaning Clothes -- Titan's Ocean? -- Synthetic Success -- Crisis Mapping

Good-bye, Laundry
Talk of clothing that keeps itself clean, or that at least does not need conventional washing, has percolated for decades. Manufacturers have expressed interest in the technologies underlying such garments, but so far the only advance available commercially is clothing treated with nanoparticles that change the natural characteristics of the fabric to keep stains from soaking into it. That makes dirt easier to wash away. The technology, created by textile company Nano-Tex in 2001, appears in clothing today by retailers Eddie Bauer, Gap and Hugo Boss, to name a few.

Perhaps the most serious customer for self-cleaning clothing right now, though, is not the average mall shopper but U.S. military personnel, who might face long stretches between clothing changes. Chemist Jeff Owens is working with others at Tyndall Air Force Base in Florida on a process that fuses chemicals onto fabric, resulting in material that resists fire, oil and water and that also kills bacteria. Owens’s team is aiming to have the technology ready for preliminary demonstrations in 2009.

Despite today’s limited market, the quest for self-cleaning clothing with the potential for broader use continues. Researchers at Monash University in Australia have found a way to coat keratin protein fibers, such as wool, hemp and silk, with titanium dioxide nanocrystals that oxidize food and dirt in sunlight. According to lead researcher Walid Daoud, the process, outlined in the February 26 Chemistry of Materials, does not employ toxic reagents and is harmless to skin. The drawback: speed, or lack thereof. It takes 20 hours in the sun for a wine stain to disappear.

Karen Schultz


Waves below the Crust

Astronomers have wondered about the possibility of water—and, hence, of life—on Saturn’s moon Titan [see “The Mystery of Methane on Mars and Titan”; SciAm, May 2007]. Researchers modeling Titan conclude that a huge ocean may lie underneath the surface, which would explain observations by the Cassini probe that found peculiar shifts in Titan’s rotation and landmarks on the surface. The ocean may have resulted from heat from radioactivity at the moon’s core that melted a layer of frozen water. Luckily, the idea is testable: a subcrustal ocean would speed up Titan’s rotation rate in the coming year or two, followed by a slowdown—something that can be measured on succeeding Cassini flybys.

—J.R. Minkel


First Artificial Enzyme
With the goal of making synthetic biological components [see “Engineering Life: Building a Fab for Biology”; SciAm, June 2006], researchers have crafted the first artificial enzyme—specifically, an enzyme that removes a proton from a carbon atom. The team, from the University of Washington, the University of California, Los Angeles, and the Weizmann Institute of Science in Rehovot, Israel, used a computational model to devise potential enzymes constructed from 200 amino acids. After finding the enzyme that showed the most activity, the group further improved it by making it undergo evolution in a test tube. Seven rounds of evolution—the introduction of mutations—improved the enzyme’s efficiency 200-fold. Nature published the study online March 19.

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