#96-92
Mailed 12/19/96

BNL SPOTLIGHTS



NOTE TO EDITORS: "BNL Spotlights" is issued periodically to bring you up to date on some of the latest newsworthy developments at the U.S. Department of Energy's Brookhaven National Laboratory. For more information on any of these items, call Diane Greenberg or Mona S. Rowe at BNL's Public Affairs Office at (516)344-2345.

MEASURING THE BIOLOGICAL EFFECTS OF RADIATION IN SPACE

Traveling beyond the protection of the Earth's geomagnetic field, astronauts are constantly bombarded with radiation from outer space, which is different in particle composition from radiation people are exposed to on Earth. Prompted by concern that this space radiation may cause biological damage, NASA is performing experiments to determine its effects, with the use of BNL facilities and the expertise of Brookhaven's biologists.

At BNL's particle accelerator, the Alternating Gradient Synchrotron, Brookhaven biologists aimed particles called heavy ions at cultured human cells to determine the level at which this ionizing radiation would induce double-stranded breaks in DNA, the most serious damage ionizing radiation could produce. Using a new experimental technique developed at Brookhaven, the researchers found that these breaks in DNA occurred at extremely low doses of heavy ions - as small as one-hundredth of a Gray. (One Gray is a measure of 100 rads. Therefore, one-hundredth of a Gray is equal to one rad.) Previous experiments had only measured damage at 100 times this dose, or one Gray (100 rads). The Brookhaven researchers' next experiments will determine how well the cells repair the DNA damage.

INVESTIGATING THE OZONE HOLE

Recently, Brookhaven researchers have made important advances in understanding the mechanisms of ozone depletion. Ozone can be a form of pollution, impairing people's vision and breathing, but in the stratosphere, it protects life on Earth from the harmful effects of ultraviolet radiation from the sun, such as skin cancer. Scientists started taking measurements of stratospheric ozone in the early 1950s and they have found that since 1978, the ozone layer is thinning. Over the south pole, ozone completely disappears at some altitudes by the end of every October, creating what is known as the ozone hole. This ozone hole is a matter of concern because it has been growing over the last two decades. Moreover, a similar hole can now also be observed over the north pole.

Most scientists believe that an increase in chlorofluorocarbons, or CFCs, which come from refrigerants, solvents and aerosol sprays, trigger chemical reactions that cause ozone depletion. Once the CFCs rise some 7 to 30 miles into the stratosphere, they are exposed to ultraviolet rays, which break them apart chemically, resulting in the release of chlorine. When the chlorine is activated by certain particles in the stratosphere, it can destroy ozone.

At Brookhaven, researchers have created particles containing sulfuric acid and water that they believe duplicate the chlorine-activating particles in the stratosphere. They then placed these particles in polar stratospheric conditions that they mimicked in their laboratory and observed a new, unexpected crystalline form that they predict will be extremely effective at chlorine activation. These observations provide one of the missing links between nature and theory.

CONVERTING ASHES AND CORNSTARCH
TO CORROSION-RESISTANT COATINGS

Brookhaven researchers are making two different, but effective, coatings that are resistant to corrosion and oxidation by recycling fly-ash waste from blast furnaces used in the steel industry, and modifying cornstarch, a very abundant, renewable natural resource in the U.S.

The recycled fly-ash is chemically treated, sprayed onto high-temperature performance metal and baked at temperatures as high as 300ºC to make the metal resistant to the deleterious effects of oxidation and abrasion. A corrosion-resistant coating made from nonbiodegradable cornstarch has also been developed through chemical modification. The performance of this coating is comparable to that of conventional ones, but it is environmentally friendlier and less expensive to make. Both coatings are being patented, and Brookhaven soon will be seeking industrial partners to commercialize them.

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