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In This Issue:
Physicists Probe Puzzles of Heavy Metal Stars
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Astronomy
Physicists Probe Puzzles of Heavy Metal Stars
Nature, very thoughtfully, gave every element an identifying signature. Even different forms of the same element--atoms, ions and isotopes--have a unique signature that corresponds to how they absorb and emit light. Astronomers take advantage of this fact to figure out what stars are made of, and they've made some pretty surprising findings.
Take, for example, the star known as chi Lupi that contains 100,000 times the normal amount of mercury. Even more surprising is the fact that the mercury in this star is all a relatively rare isotope of natural mercury. Two physicists at the National Institute of Standards and Technology, Joseph Reader and Craig Sansonetti, helped NASA scientists determine which form of mercury was in chi Lupi by making exacting measurements of ionized mercury isotopes.
NASA recently sought their assistance again in determining which isotope of lead was present in this very unusual star. The NIST physicists determined the spectral signature of doubly ionized lead to confirm its presence in the star. They also made measurements on a few milligrams of pure lead isotopes, one of which had never before been done. These results helped NASA determine that the lead in chi Lupi is probably all a single isotope, which constitutes only one-fifth of the lead that occurs naturally on Earth.
Media Contact:
Linda Joy (301) 975-4403
Dental
Dental Drilling Can Be Enough to Make a Tooth Crack
The sound of a dental drill alone is enough to give most people goose bumps. Unfortunately, it also may be giving them subsurface cracks in their teeth. With funding from the National Institute of Dental Research, researchers at the National Institute of Standards and Technology recently completed a collaborative study of drilling damage to teeth during preparation with diamond-impregnated cutting tools or "burs."
Conducted with the University of Medicine and Dentistry of New Jersey, the Naval Dental School and the University of Maryland at Baltimore, the study found that removing tooth enamel with a coarse diamond bur produced subsurface cracks 50 to 110 micrometers long. Coarse burs also produced many smaller microcracks that, combined with the longer cracks, may make drilled teeth more susceptible to fracture. The research found that fine diamond burs were effective in removing damaged areas caused by the coarser burs. To avoid subsurface cracking, the researchers concluded that dentists should use coarse diamond burs only for partial drilling and then finish the job with a finer diamond bur.
Media Contact:
Gail Porter (301) 975-3392
Energy
Interest Heats Up for Photovoltaic Water Heater
As any person with a budget can tell you, hot water costs money. Maybe that's why everyone from the U.S. Air Force to Walt Disney World has taken an interest in the National Institute of Standards and Technology's energy-saving photovoltaic solar water heaters. The NIST system consists of an array of photo-voltaic modules, a water storage tank incorporating multiple electrical resistive elements, and a microprocessor controller. Changes in light intensity register on the microprocessor, which in turn triggers the appropriate electrical resistive elements for maximum energy conversion from sunrise to sunset.
This month the Air Force begins a two-year evaluation of the water heating devices at two of its Okinawa Camp Lester housing units. Currently, the U.S. military spends more than $7.5 million per year to provide hot water to U.S. military housing units in Okinawa, Japan. Researchers hope to cut energy consumption by 75 percent in the test units.
Walt Disney will feature the solar water systems in its hands-on "Biovention" exposition of the world's new products and inventions Jan. 11-15, 1998, at Walt Disney World's Epcot Center at Lake Buena Vista, Fla. A NIST mechanical engineer will explain the system and field questions.
Media Contact:
John Blair (301) 975-4261
Fire
All Aboard! NIST Takes a New Look at Train Safety
When a fire starts in an enclosed space, like a passenger train compartment, time is of the essence. Everything about the design of the compartment--from the materials used for curtains, seats and carpets to the number of exits and the width of aisles--determines whether passengers will have enough time to exit a train car safely.
As part of a three-year study of passenger train fire safety requirements for the Federal Railroad Administration (under the direction of the Volpe National Transportation Systems Center), researchers at the National Institute of Standards and Technology recently conducted full-scale tests in their fire research facility.
Using bags of trash collected from in-service trains, NIST researchers measured heat release rates to better understand the behavior of realistic train fires. The researchers are using these measurements with computer models to simulate how fires might spread in actual trains. Because these simulations take materials interactions and the size and arrangement of railway cars into account, they often can produce more realistic predictions of fire spread than materials testing alone.
Media Contact:
John Blair (301) 975-4261
Materials
New Material Likes the Layered Look
Mix a large group of middle school boys and girls at a dance and they will naturally align themselves--boys on one side, girls on the other. Metallurgy and ceramics researchers at the National Institute of Standards and Technology have found two different forms of a material that will do the same thing in orderly fashion. When two types of barium-titanium-iron-oxide with different crystal structures and different concentrations of iron are mixed in, the two forms naturally align themselves into magnetic and non-magnetic layers.
The researchers are hoping that the layered materials may be useful for several applications, including heads for reading magnetic data on computer disk drives, high-density magnetic data storage and focusing elements for neutron beams. Currently, high-tech read heads are made by an expensive process in which each layer is sputtered onto a surface. The new oxide material may provide a less expensive, more uniform way to make these layered structures. Also unlike current multilayered read head materials, the new materials are stable at temperatures above 1000 degrees Celsius.
Media Contact:
Gail Porter (301) 975-3392
Technology
New Website Shows How NIST Is in Your City Every Day
Look around you and what do you see? Your answer probably wasn't the National Institute of Standards and Technology--but it could have been.
After nearly a century of working with U.S. industry, NIST has put its mark on the structure and function of many aspects of U.S. society. Yet, many Americans are unaware of the NIST technology infrastructure. That is why the agency has introduced a new World Wide Web site called "NIST and Your City."
NIST's homepage (www.nist.gov) links to NIST and Your City where you'll find a cartoon of a typical American community. Browsing through the icons provides a self-guided tour of how NIST research and services improve quality of life and make U.S. industry more competitive in the global marketplace. For example, visitors can learn that:
- building code officials around the country have long relied on NIST's fire research expertise to assure fire safety;
- NIST provides standards for forensic laboratories to verify the accuracy of DNA profiles used as evidence in rape, murder and paternity cases;and
- NIST's weights and measures activities help ensure that when you buy anything sold by weight, volume or some other measurable property, you take home the amount you purchased.
Media Contact:
Michael E. Newman (301) 975-3025
Tech Trivia
During the 1920s, the National Bureau of Standards (now NIST) was besieged with requests to certify radium preparations that were promoted as cures for gangrene, cancer and other conditions. Because radium inflicted skin burns and unknown internal effects, the American Medical Association dropped it from recognized remedies in 1932.
Lyman Briggs, an avid baseball fan and former director of the National Bureau of Standards, reported that spin, not speed, determines the break in a pitched ball in a 1959 American Journal of Physics article. His experiments used a wind tunnel and the Washington Senators pitching staff.
In 1957, Ralph Stair, a National Bureau of Standards physicist, helped found Mauna Loa Observatory on Hawaii to make ultraviolet solar irradiance measurements. Now a principal observatory of the National Oceanic and Atmospheric Administration, Mauna Loa recognized Stair's efforts at a recent 40th anniversary celebration.
U.S. Department of Commerce
Technology Administration
National Institute of Standards and Technology
Editor: Linda Joy
HTML conversion: Crissy Wines
