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Measuring Mass: NIST Scientists Tackle Kilogram Problem
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Weights and Measures
Measuring Mass: NIST Scientists Tackle Kilogram Problem
Scientists love the International System of Units, which is the basis of practically every measurement in research and commerce. More precisely, they really love six of the system's seven basic units of measure, which define how we quantify such things as time, length and temperature. However, the unit for mass, the kilogram, poses a problem. The kilogram is the only unit still based on a physical standard; the other six units are based on unchanging natural phenomena, such as the speed of light or atomic oscillations. Physical standards are hard to reproduce accurately and can change over time.
Scientists at the National Institute of Standards and Technology are working to remedy this situation. They've just completed the first phase of a watt-balance experiment that can determine mass by comparing mechanical and electrical power through calculations based on other quantum standards. Their system can measure mass accurately to seven decimal places and with refinements could reach eight or more decimal places. That would rival the accuracy with which scientists currently can measure the physical kilogram standard and would eliminate the disadvantages of basing mass on a physical standard. NIST scientists are presenting their electronically derived kilogram results at the Conference on Precision Electromagnetic Measurements in Washington, D.C., July 10.
Media Contact:
Linda Joy, (301) 975-4403
Refrigeration
Shedding Light on Chilling Out
Cooling large buildings may become significantly less expensive as air conditioning manufacturers switch to more energy-efficient lubricants. The National Institute of Standards and Technology has devised a new way of using fluorescent light that will make it much easier to choose the best lube for the job.
Lubricants keep a cooling system's compressor running smoothly in much the same way that oil helps a car's engine to operate properly. NIST researchers developed a novel way to measure the amount of lubricant that was mixing in with the refrigerant in cooling systems and accumulating on the surface of certain components. Furthermore, research indicates that lubricants that partially mix with the refrigerants and have high viscosity can improve the performance of the refrigerants by as much as 18 percent. This finding will allow air-conditioning manufacturers to design better cooling systems.
The fluorescent light measuring method combined with the new information about which lubricants enhance the performance of cooling systems--most lubricants have the opposite effect--is expected to save millions of dollars in energy costs as cooling system designers produce more efficient air-conditioning units.
Media Contact:
Philip Bulman, (301) 975-5661
Refrigeration
Super Insulation Keeps Its Cool
If you could fit your whole house into a vacuum-insulated ice chest, you could count on lower air conditioning and heating bills. This is the basic idea behind a new class of insulation panels that have been under development for the past several years. It's an idea that also has applications for refrigerated trucks, home refrigerators, vending machines and other products.
To help manufacturers determine the R-value, or resistance to heat flow, for these new panels, researchers from the National Institute of Standards and Technology have developed a calorimeter that measures heat conducted both through the panel and around its edges. Through a cooperative research and development agreement, NIST researchers recently completed R-value measurements on a new vacuum insulation panel that uses a novel fill material developed by Dow Chemical Co. They found that the new panels had an R-value approximately six times higher than traditional glass-fiber insulation and that a 2.5 cm (one-inch) advanced panel had about the same R-value as 15 cm (6 inches) of glass-fiber. To date, these measurements represent the highest resistance to heat flow of any advanced insulation panel measured at NIST. Refrigerators made with the new panels could have thinner walls for greater interior space but still be more energy efficient than current models.
Media Contact:
Philip Bulman, (301) 975-5661
Medicine
Outside Help for Deficient Bone Marrow Cells
Treating a disease is not always enough; sometimes the treatment needs a remedy too. An example is cell-transplant therapy, which involves the costly and often painful extraction of large amounts of stem cells (which mature into blood and immune system cells) from a donor's bone marrow or blood. Stem cells are given to patients whose own stem cells are absent or damaged, often because of chemical or radiation treatments for cancer. But a new approach to growing stem cells may cut the costs of this procedure by up to 25 percent while also reducing complications and donor pain.
Now in clinical trials is a desktop-sized bioreactor designed and constructed by Aastrom Biosciences, Inc., of Ann Arbor, Mich., with co-funding from the Advanced Technology Program of the National Institute of Standards and Technology. Starting with a much smaller volume of harvested cells than is collected for conventional therapies, the bioreactor can grow enough functional stem cells for transplant. The results of preclinical trials were promising. For example, two studies showed that cells grown outside the body were less contaminated with tumor cells than the patients' own bone marrow, suggesting that cancer may be less likely to recur after treatment.
Media Contact:
Michael Baum, (301) 975-2763
Public Safety
NIST Helps to Answer a Siren
's Call for StandardsThe answer is "Sounds of Sirens." The question is not name the never-released sequel to a 1964 hit single by Simon and Garfunkel. Rather, it is what does the National Institute of Standards and Technology propose to measure more systematically so that audible warning devices on emergency vehicles perform as needed?
For the National Institute of Justice through NIST’s Office of Law Enforcement Standards, physicist Randy Wagner reviewed existing performance standards for emergency vehicle sirens. He identified four--each with its own peculiarities. The result is a confusing state of affairs for manufacturers, certification agencies, and public-safety and emergency-service officials. "For reasons of safety and because of liability concerns," says Wagner, "there's considerable interest in developing a consistent set of testing procedures and performance criteria."
A comprehensive standard, he explains, should include measurements to determine how well a siren's sound output--the wails and yelps that reach our ears--spreads in front of the vehicle at intersections. It also should assess performance averaged over several "sweeps," especially after the siren loudspeaker has warmed up, since heat causes the sound level to decrease.
Wagner is now working with the Society of Automotive Engineers on a revision of its "recommended practice" for emergency vehicle sirens. His goal is to develop a single standard that can be referenced by all organizations, from manufacturer to certification agency to police, fire or ambulance service.
Media Contact:
Mark Bello, (301) 975-3776
Manufacturing
Hands-On Help Puts Small Company in the Spotlight
Like the product it sells, the future is shining brightly for Streamlight Incorporated. Located in Norristown, Pa., this small company of 105 employees manufactures portable lighting products for sale in the United States and around the world. Faced with growing demand for its product, the company wanted to improve productivity without incurring unmanageable labor costs.
Streamlight Incorporated turned to the Delaware Valley Industrial Resource Center, a local affiliate of the nationwide Manufacturing Extension Partnership, a program of the National Institute of Standards and Technology. The center worked with Streamlight to analyze its existing manufacturing techniques and to implement new, more efficient processes. The results are impressive: productivity increased by 40 percent, sales grew from $17 million to $24 million in two years, work-in-progress inventory dropped by almost 90 percent, previously subcontracted work is now done in-house, lead times decreased from three weeks to one week, and overall quality improved.
With a nationwide network of over 2,000 manufacturing experts, the Manufacturing Extension Partnership is helping small and mid-sized manufacturers improve productivity, increase profits and enhance competitiveness. Smaller manufacturers can call (800) MEP-4MFG (800 637-4634) to reach the nearest center or visit http://www.mep.nist.gov on the World Wide Web.
Media Contact:
Jan Kosko, (301) 975-2767
Tech Trivia
Alaska, the 49th state, received official U.S. measurement standards in a ceremony held at the National Bureau of Standards (now NIST) on March 3, 1959. The set included a yard-meter bar, a 100-foot steel measuring tape, capacity standards ranging from 5 gallons to 2 ounces, and mass standards ranging from 50 pounds to 0.1 ounce.
In 1985, astronomers at JILA, a collaboration between NIST and the University of Colorado, detected the presence of strong magnetic fields on the surface of a flare star. This finding helped in understanding of stellar activity, such as flares, "spots" and hot coronas on some stars.
In 1985, scientists at the National Bureau of Standards (now NIST) reported the first trapping of neutral atoms. Prior to 1985, only charged atoms, or ions, could be held in a trap with an electromagnetic field. This achievement was a significant advance in atomic physics, opening a new generation of experiments on ultracold atoms.
U.S. Department of
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National Institute of Standards and Technology
Editor: Linda Joy
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Last update: July 16, 1998
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