A capsule newsletter of science and technology news briefs from NIST written for general audiences; published monthly

February 1998

Tech Beat

In This Issue:

blueball.gif - 0.93 KAtomic Clock in Space Will Raise Accuracy to New Heights
blueball.gif - 0.93 KNIST Helps Light the Way to Safer Flying
blueball.gif - 0.93 KResearch Yields a Cool 433 Percent
blueball.gif - 0.93 KResearchers Seek Greenhouse Gas Substitutes
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Tiny Portals Could Open New Way to Sequence DNA
blueball.gif - 0.93 KEven Packaging Needs Packaging
blueball.gif - 0.93 KTech Trivia

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Atomic Clock in Space Will Raise Accuracy to New Heights

Seeds, spiders and even a U.S. Senator have been shot into orbit. Now add to this eclectic list plans to launch an atomic clock. NASA has awarded a microgravity research grant to the National Institute of Standards and Technology to develop an atomic clock of unprecedented accuracy. NIST will place the clock on the International Space Station in five to seven years.

The performance of atomic clocks depends on how long individual atoms can be observed. On Earth, the observation time is limited because the atoms are accelerated by gravity and leave the clock's observation chamber quickly. In microgravity, the observation time can be increased by a factor of 10 or more, and NIST projects the accuracy of the space clock will be at least 10 times better than the best Earth-bound clocks.

Researchers will use it to perform a variety of tests of important physics theories, including measurements of how gravity affects the rate of a clock and a possible test to confirm that the speed of light is truly the same in all directions. They also will use it to study the orbits of Global Positioning System satellites, which could lead to improved accuracy for certain applications, such as surveying.

Media Contact:
Collier Smith (Boulder) (303) 497-3198

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NIST Helps Light the Way to Safer Flying

Air traffic controllers do an amazing job keeping aircraft safely separated. But with crowded skyways there are bound to be mistakes or equipment failures. As a last line of defense, pilots rely on old-fashioned visual sighting to avoid collisions. To make planes more visible--especially at night and in bad weather--the Federal Aviation Administration requires planes to have red or white flashing anti-collision lights with minimum intensity of 400 candelas. Accurately measuring intensity for a flash that lasts only a split second, however, is fairly tricky. Field intensity measurements of anti-collision lights on commercial aircraft have differed by as much as 30 percent using accepted light intensity measuring instruments. This indicated a critical need to develop a calibration standard for flashing light intensity measurements.

The FAA asked the National Institute of Standards and Technology to develop this standard. NIST physicists came up with a system that uses two independent calibration methods to produce a primary standard photometer system with an uncertainty of only 0.6 percent. NIST now is using the system to provide calibrations for reference photometers used by instrument makers, aircraft manufacturers and the airlines. They hope the calibrations service and recently agreed on standard measurement methods will improve uncertainty for field measurements to less than 10 percent.

Media Contact:
Linda Joy (301) 975-4403

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Environmental Economics

Research Yields a Cool 433 Percent

E nvironmentally, and now economically, speaking, alternative refrigerants research at the National Institute of Standards and Technology is yielding stratospheric returns. A recent study by TASC Inc. estimates that the federal investment in NIST work to help industry find replacements for ozone-depleting chlorofluorocarbons has yielded a social rate of return of 433 percent and a benefit-to-cost ratio of almost 4 to 1.

These dividends are the result of cost savings by firms prior to the 1996 deadline for phasing out CFCs. For a sample of 11 firms, NIST expenditures of nearly $2.7 million translated into savings totaling about $14.2 million. Benefits are indicative of those realized by two industrial sectors strongly affected by the agreement to protect the stratospheric ozone layer: suppliers of refrigerants and makers of heating and cooling equipment. In all, NIST has distributed more than 500 copies of its REFPROP program, a computer package for calculating the properties and modeling the behavior of refrigerants and their mixtures.

Timely delivery of reliable data on the properties of alternative refrigerants made the search for CFC replacements more efficient, the study found. In addition to sparing companies the costs of considerable, and likely duplicative, research, NIST's work produced other benefits. For example, there is a reduction in so-called transaction costs due to buyer-seller disagreements stemming from the almost-inevitable variability and uncertainty in data generated by individual firms.

Media Contact:
Mark Bello (301) 975-3776

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Researchers Seek Greenhouse Gas Substitutes

Say "global warming," and many think ecological disaster--from flooded East Coast cities to drought in the wheat belt. It's all debatable, but last December, leaders from 190 countries meeting in Kyoto, Japan, decided to act. The final United Nations Kyoto conference agreement calls for the worldwide regulation of six potentially climate-changing gases.

One of these gases, called a "greenhouse" gas because it traps heat around the Earth, is sulfur hexafluoride, a synthetic gas used in electric power transmission and distribution equipment. Due to increased usage, its concentration in the environment is climbing by approximately 8.7 percent a year. Although this gas accounts for only 0.01 to 0.07 percent of humankind's contribution to global warming, it is especially effective in trapping infrared radiation and has an atmospheric life of nearly 2,000 years.

National Institute of Standards and Technology researchers have tackled the problem. They have determined the physical and chemical requirements for potential sulfur hexafluoride replacements. They also have concluded that mixing it with environmentally benign nitrogen may be suitable for many applications. In addition, the researchers found high-pressure nitrogen to be a promising gas for high-voltage insulation and mixtures of sulfur hexafluoride and helium promising for use in circuit breakers.

Media Contact:
John Blair (301) 975-4261

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Tiny Portals Could Open New Way to Sequence DNA

Technologies to decipher patterns in DNA, the biological molecule that codes for an individual's genetic make-up, take far less time than they used to. But they still take hours and involve multiple steps and sophisticated laboratory equipment. A team of scientists at the National Institute of Standards and Technology, Harvard University and the University of California at Santa Cruz is now exploring a possible new way of reading a strand of DNA that is potentially much faster than existing techniques.

The scientists are developing a system that forces single-stranded DNA through a tiny portal in a thin lipid membrane. In fact, the system monitors the passage of a single DNA molecule through a single nanometer-scale pore. The investigators apply a voltage across the membrane, which forces charged DNA strands through the hole. The scientists suggest that it might be possible to use this system to identify single bases, the "letters" in the genetic code, within long strands of DNA. This might be possible if each base causes a unique change in the current flowing through the pore. There are many technical hurdles to overcome before the system could have practical applications. However, if successful, the time to sequence DNA could be reduced substantially.

Media Contact:
Linda Joy (301) 975-4403

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Even Packaging Needs Packaging

Lydall Inc., a Richmond, Va., small manufacturer, needed help with what was literally a sticky problem, improving a gluing operation that had become a production bottleneck. Lydall manufactures a range of cardboard products used by the beverage industry. One of the plant's top sellers is a tray sheet used to organize empty soda bottles on pallets. To keep the bottles together without having to apply shrink wrap over the entire pallet, an extra one-inch strip of cardboard is glued along each edge of the sheet. This saves the bottle manufacturer about 50 cents a pallet and allows the tray sheets to be reused.

But, while the reinforced tray sheet is a winner, attaching the cardboard strips along each edge is a tedious, hand-labor job. Lydall asked Virginia's A.L. Philpott Manufacturing Extension Partnership for help. After implementing Philpott MEP's recommendations, Lydall has reduced cycle time on the gluing line by about 40 percent and is planning to automate its gluing operation. Says Ed Smith, Lydall plant manager, "It enables us to meet our customers' delivery needs while reducing costs and keeping the product competitive." The A.L. Philpott MEP is an affiliate of the National Institute of Standards and Technology's Manufacturing Extension Partnership, a nationwide network of centers offering technical and business assistance to smaller manufacturers

Media Contact:
Jan Kosko (301) 975-2767
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Tech Trivia

The Boulder Laboratories of the National Bureau of Standards (now NIST) were among the first in the United States to obtain radio broadcasts from the Soviet satellite Sputnik I in 1957.

During WWII, the National Bureau of Standards (now NIST) assisted in the joint Army-Navy program to determine the characteristics of sky glow from artificial sources and the extent to which sky glow and shore lights might aid hostile ships offshore.

In 1915, the National Bureau of Standards (now NIST) published Circular 55, Measurements for the Household, its first best-seller. Called a "treatise on domestic science," it described in simple language the operation of common household measuring devices. At 45 cents each, more than 33,000 copies were sold.

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U.S. Department of Commerce
Technology Administration
National Institute of Standards and Technology

Editor: Linda Joy
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