Developments to Watch
It's a Bug's Life Fighting E. Coli in Cattle
One of the deadliest bugs found in food or drinking water is a bacterium called E. coli 0157:H7. Most strains of E. coli are harmless. But the 0157 type sickens 60,000 Americans a year. Since outbreaks are often caused by contaminated cattle or manure, the problem could be reduced by eliminating the microbe from the animals.
One clever approach: enlisting other bacteria in the fight against their deadly relative. Michael P. Doyle of the University of Georgia began by isolating "friendly" E. coli bugs from the stomachs of cattle. Some of them, he found, secrete substances capable of killing the 0157 strain. So he put them to the test. He gave 20 steers big doses of 0157. Then he sprayed good bugs on the feed given to half of the steers.
The results were impressive. In the animals which got both strains, the good bugs quickly outcompeted the bad ones. Within 30 days, 0157 had vanished from the manure of all 10 steers and from the guts of 9 of the 10 animals. Says Doyle: "This is the most promising practical approach" to tackling the E. coli 0157 problem in animals. The university has patented the scheme, and Alpharma Inc. in Fort Lee, N.J., is commercializing the bugs.By John CareyReturn to top
Making Solar Cells on the Cheap
Electricity from the sun has been long on promise, but short on results. The central problem? Semiconducting materials that efficiently turn the sun's rays into a flow of electrons are expensive to make. But new approaches using "nano" particles--measuring only a few billionths of a meter--offer hope of breaking the logjam.
At the University of California at Berkeley, Paul A. Alivisatos has been able to embed tiny crystals of semiconducting cadmium selenide in a polymer. When light strikes, electrons flow from crystal to crystal. The approach is far cheaper than the usual method of building devices on a chip. To increase efficiency, the trick is to make the crystals in clever shapes, Alivisatos says. The first devices contained short rods, and were about 2% efficient. Longer rods gave better results. Then, he developed a way to create crystals with four arms, so that the arms lined up. This new shape makes it easier for the electrons to flow and could boost efficiency to over 20%--comparable to far more expensive existing solar cells.By John CareyReturn to top
A Fish Story: How Reserves Foster Marine Life
Thanks to overfishing, habitat loss, and pollution, populations of fish and other marine creatures are plunging--with serious consequences for the oceans and those who eat marine life. One proposal has been to set up reserves where fishing is banned. The hope is that species will rebound in the protected areas and repopulate nearby fishing grounds. But without proof, it's been difficult to persuade governments and fishermen to allow reserves to be created.
Now the proof is in. A study of more than 80 reserves reveals that the amount of marine life they harbor can triple in as little as two or three years, reports ecologist Robert R. Warner of the University of California at Santa Barbara. Equally important, catches in nearby unprotected areas improve sharply, which enables fishermen to more than make up for the loss of some fishing grounds to reserves. Researchers showed that the best approach is networks of small reserves.
The new results have begun to turn fisherman into strong backers, says Callum Roberts, a conservation biologist at Harvard University.By John CareyReturn to top