In This Issue: Measure Mercury More Accurately with New Mussel Tissue Standard Modeling Soldering: Scientists Tackle Tiny Trouble Spots Molding the Future of Auto Bodies Innovative Concept May Solve Composites Problem Partners Pave Way for Advanced Space Observatories Mini CAT Scans Check Out Circuits Tech Trivia
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Measure Mercury More Accurately with New Mussel Tissue Standard
Mollusks, such as clams, oysters and mussels, make tasty chowders, stuffings and appetizers, but marine scientists may prefer a new mussel standard from the National Institute of Standards and Technology. The new Mussel Tissue Standard Reference Material will ensure accuracy for scientists who measure trace elements, such as mercury, cadmium and lead, in marine life.
Since mercury and other toxic metals can accumulate in mussels, oysters and other mollusks, scientists monitor these species as sentinels to flag attention to dangerous pollutants in the environment. The Environmental Protection Agency has recently targeted one such pollutant, mercury, for reduction. In order to assess the success of reduction efforts, environmental scientists must be able to measure mercury in marine tissue very accurately.
The new mussel tissue standard (SRM 2976) includes 25 grams of freeze-dried mussel tissue. NIST scientists very accurately measured levels of mercury and other trace elements in the mussel tissue. Marine scientists can use it as a chemical ruler to gauge the accuracy of their own analytical measurements and methods. It is available from the NIST Standard Reference Materials Program for $354.
Linda Joy, (301) 975-4403
Modeling Soldering: Scientists Tackle Tiny Trouble Spots
As microelectronic circuits continue to shrink, it becomes increasingly difficult to properly solder their numerous, fine and tightly packed interconnections. The failure of one soldered joint only a few thousandths of an inch wide can spell doom for an entire electronic device.
The solder issue has become so critical that a team of scientists has been formed to attack the problem in a novel way. Now, those scientists are being credited with helping American industry save time and money by enlisting computer modeling that uses basic physics to design soldered connections.
The model predicts which types of joints are likely to fail--and when--by calculating their precise shapes, enabling the accurate simulation of the accelerated effects of environmental stresses, such as constantly changing temperatures, which cause wear by expansion and contraction.
The Solder Interconnect Design Team includes scientists from the National Institute of Standards and Technology, the Massachusetts Institute of Technology and Susquehanna University, who recently won a national award for working with their industrial counterparts to adopt the modeling software.
Emil Venere, (301) 975-5745
Molding the Future of Auto Bodies
The first ballpoint pen, goes the manufacturing saw, costs you a hundred grand. But the second costs only pennies. Success lies in a process that allows you to produce large quantities of your product quickly and cheaply.
Design Evolution 4, a small firm in Lebanon, Ohio, believes it has that process for the car of the future. DE4 developed a molding system that creates the one-piece composite chassis of the Solectria Sunrise electric sedan. Developed by the Northeast Alternative Vehicle Consortium (Boston, Mass.) with support from the National Institute of Standards and Technology's Advanced Technology Program and the Defense Advanced Research Projects Agency, the Sunrise is a full-featured, all-composite electric vehicle. Its novel one-piece construction eliminates hundreds of individual parts, reduces the body/chassis weight to 350 pounds, and provides extraordinary crash-worthiness.
But to be commercially viable, such a vehicle needs a rapid, low-cost manufacturing process. DE4's solution was a unique multiport injection mold. The rate of flow for each port can be adjusted individually throughout the process for the greatest efficiency. The DE4 system has cut the cycle time required to mold a complete Sunrise chassis from a matter of hours to about 30 minutes. DE4 is now working to automate the process fully and cut time even further.
Michael Baum, (301) 975-2763
Innovative Concept May Solve Composites Problem
The nation's auto makers are striving to one day replace machined steel parts with a new generation of lightweight composites that are made by filling molds with powdered metal and then applying high pressure. The so-called metal matrix composites can be produced quickly, at a fraction of the cost of conventional, machined metal parts, and it is hoped that they might be used eventually for even the most demanding applications, such as engine connecting rods.
However, the technology only works if the powdered metal can be made to flow readily through a feeder tube, into a mold--or die--where it is pressed into shape. The best-quality metal composites require the finest powders. But the finest powders don't flow as well as coarser powders; they tend to stick in the feeder tube, clogging the system instead of flowing into the die.
With help from the National Institute of Standards and Technology, a small Virginia company has developed a possible solution to the problem. MATSYS Inc., of Springfield, has designed a system that mixes air with the metal powder. The air acts as a sort of lubricant, inducing the powder to flow smoothly. Ongoing research is being funded through the Small Business Innovation Research program.
Emil Venere, (301) 975-5745
Partners Pave Way for Advanced Space Observatories
Orbiting 596 kilometers (370 miles) above the Earth's atmosphere, the Hubble Space Telescope has revolutionized astronomy with its unparalleled views of the universe. However, an incorrectly shaped main mirror detected after its 1990 launch almost negated Hubble's intended focusing power of 10 times better than anything terrestrial. It took a 1993 space shuttle repair mission--and 35-½ hours of spacewalks--to correct the mistake.
Officials at NASA's Marshall Space Flight Center in Huntsville, Ala., want to eliminate any chance of repeating history as they build the next generation of orbiting telescopes. Therefore, MSFC teamed with the National Institute of Standards and Technology to develop the first set of standards and test procedures to ensure accurate measurements during the construction of large-diameter optics. Eventually, these will be shared with U.S. optics companies, helping improve product quality and lower manufacturing costs.
With the NASA/NIST procedures in place, MSFC officials hope to greatly increase mankind's visual reach to the stars. For example, the next-generation space telescope's 8-meter (25.6-foot) mirror will dwarf Hubble's 2.4-meter (7.6-foot) mirror, yielding 10 times more light-gathering ability. So, where Hubble can see the light emitted by stars 12 billion years ago, the new telescope is expected to capture the first light emitted in the universe.
Michael E. Newman, (301) 975-3025
Mini Cat Scans Check Out Circuits
Computer-aided tomography has been a major boon to medicine, allowing doctors to construct three-dimensional X-ray images of structures inside the body. Now, NIST scientists are hoping to apply the technology of CAT scanning to diagnosing microcircuit maladies.
As reported in Applied Physics Letters (Jan. 4, 1999), researchers from the Digital Equipment Corp., Rensselaer Polytechnic Institute, Argonne National Laboratory and the National Institute of Standards and Technology have demonstrated the use of computer-aided X-ray tomography to make three-dimensional images of microelectronic interconnects buried within an integrated circuit. (see graphic). While medical CAT scans typically image features as small as 0.5 millimeters, the microtomography instrumentation used by the current NIST group achieved a resolution of just 400 nanometers across, or 1,250 times smaller.
As microcircuit features continue to both shrink and become more complex, the semiconductor industry needs a reliable, fast way to inspect circuit connections with a resolution of tens of nano-meters. The NIST collaborative project hopes to ultimately provide the semiconductor industry with a tool for imaging circuitry in cubes measuring 10 or more micrometers on a side with a resolution of about 50 nanometers. Such a resolution would meet the production needs of the industry in the year 2002 as projected in the National Technology Roadmap for Semiconductors.
Linda Joy, (301) 975-4403
NIST was twice listed in the Guinness Book of World Records for the highest frequency measured, the first time in 1974 and the second in 1979. The Time and Frequency Division in Boulder, Colo., made the measurements on emissions from iodine and helium lasers, respectively.
In 1836, a joint resolution of Congress directed the Secretary of the Treasury to deliver an 82" brass bar for length, a brass troy pound for weight, and a brass gallon and bushel for volume to the governor of each state to establish a uniform standard of weights and measures throughout the United States.
NIST's first decade (1901-1911) saw the beginning of aviation, long-distance telephone service, the diesel engine, high-speed tool steel and the first real plastic (bakelite). NIST developed the precision measurements and standards necessary to advance these young industries.