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NIST Develops Instruments to Measure Rail Wheel Stress
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Materials
NIST Develops Instruments to Measure Rail Wheel Stress
The failure of railway wheels due to stress cracking is not a frequent occurrence, but when it happens the consequences can be devastating: witness the derailment of a high-speed train last June in Germany. The National Institute of Standards and Technology has worked with the Federal Railroad Administration and the Association of American Railroads for some years to develop a routine test for railway wheel stress that may lead to cracking. Raymond E. Schramm, a recently retired member of NIST's Materials Reliability Division, Boulder, Colo., has developed a system whereby ultrasonic waves are sent through a railroad wheel rim and echoed back. By measuring the very small difference in travel time of two waves as they pass through the rim of a railroad wheel, scientists can determine the hoop stress and the conditions that could lead to cracking and failure of the entire wheel. The instrumentation package is compact, assembled largely of commercial electronics, highly automated (requiring little training) and easy to use. Two possible uses of the system are in quality control at the wheel factory and as a screening tool in a shop environment to evaluate the condition of wheels during routine maintenance and inspection.
Media Contact:
Fred McGehan (Boulder), (303) 497-3246
Electronic Books Workshop
NIST Writes the Next Chapter in Book Publishing
A new industry will emerge in the next year as several manufacturers begin selling electronic books. These hybrid products combine features found in books and computers. For example, touch screen technology allows a reader to touch an unfamiliar word to get an immediate dictionary definition. Touching the screen elsewhere can make the print larger or smaller. Yet another touch allows a reader to underline a section using a plain old fingertip instead of one of those yellow markers.
Several recent technological advances have converged in a way that makes electronic books both technically and commercially feasible. Electronic book manufacturers expect to take advantage of developments in fields such as video display technology and computer storage capacity.
The National Institute of Standards and Technology will be host to the first meeting of its kind for this nascent industry to bring together publishers, teachers, electronics executives and others with an interest in electronic books. Workshops and presentations will cover general topics such as electronic book concepts and prototypes. Some sessions will cover more detailed technical information. The workshop will take place at NIST, October 8-9.
Media Contact:
Philip Bulman, (301) 975-5661
Biotechnology
New Enzyme Structure Like Solving 30,000-Piece 3-D Puzzle
Imagine solving a 30,000-piece three-dimensional puzzle when you don't know what it's supposed to look like and when many of the pieces are identical. That's essentially what scientists at the National Institute of Standards and Technology and the Center for Advanced Research in Biotechnology did recently when they solved the three-dimensional structure of an enzyme called threonine deaminase, a large biological molecule produced by the bacteria E. coli. The enzyme structure has long intrigued scientists as it has a switch on one end for turning itself on or off.
Since the enzyme helps produce an essential amino acid for E. coli bacteria, pharmaceutical researchers now can use its structure as a target for developing new antibiotic drugs. Because plants also use the enzyme, inhibiting it may offer a new strategy for weed control. Plastics manufacturers are interested in the enzyme because it produces a compound used to make biodegradable plastics. Modifications in the enzyme could improve efficiency in biodegradable plastic production.
To solve the structure, researchers first produced crystals of the enzyme, and then computed a three-dimensional map of the structure from data they obtained by illuminating the crystals with X-rays. Next, they painstakingly matched protein building blocks to the map until the structure was solved.
Media Contact:
Linda Joy, (301) 975-4403
Standard Bullets
NIST Aims to Create THE Standard Bullet
They're not your typical bullets. In fact, they are bullet look-alikes--painstakingly designed replicas that the National Institute of Standards and Technology aims to develop into standard tools to help solve gun-related crimes.
For the National Institute of Justice, NIST plans to manufacture batches of replica bullets (and, later, cartridges), each bearing almost identical sets of ultrafine surface marks. The marks are reproductions of scratch-like grooves that a bullet acquires as it exits through the barrel. Unique to each firearm, patterns of these striations can be the next best thing to the proverbial smoking gun. They are the means to matching a bullet recovered at a crime scene to the gun that actually fired it. Detailed optical measurements of these signature patterns yield images that can be compared to images from other firearms stored in databases. However, the highest levels of accuracy are required to make definitive matches.
NIST researchers measured the pattern of striations on a fired bullet. They converted their exacting measurements into digital instructions for a computer-controlled cutting program that operated a high-precision diamond-turning machine. On a pair of unblemished bullets, the machine faithfully reproduced the striations, yielding indistinguishable prototypes of "standard bullets." Akin to specialized rulers, future versions of these measurement tools will be used by examiners to check the accuracy of instruments that match bullets to firearms.
Managed by NIST's Office of Law Enforcement Standards, the standard bullet project is key to creation of a planned integrated ballistics information network for forensics labs.
Media Contact:
Mark Bello, (301) 975-3776
Optics
Eyeball-Like Lens Systems May Improve Future Cameras
Few cameras can come close to the human eye's keen ability to detect contrasting shades of black and white, an essential measurement used by industry to rate the quality of electronic displays for computers and other equipment. Often the best displays have the highest "contrast ratios," which make for more realistic images.
While industry continually produces better displays, however, equipment used to measure contrast ratios has remained largely unchanged. One culprit is the inherent "veiling glare," sometimes called lens flair, caused by extraneous light reflecting from the surfaces of lenses and other components.
Now National Institute of Standards and Technology physicist Edward Kelley has borrowed a feature from the human eye in attempts to reduce veiling glare in lens systems. Because the eye is filled with liquid, it does not suffer from as much veiling glare typically seen in artificial lens systems. So Kelley built a prototype system containing oil between the lens and the camera's charge-coupled device, or CCD, sensor.
Initial results showed a dramatic improvement in the camera's ability to discern contrast ratios; the liquid system was nearly 70 times better than the same system without liquid. Such an innovation might one day enable U.S. manufacturers to better scrutinize displays that they plan on purchasing. Another potential application for a liquid lens system is in the growing market of digital cameras, which typically use CCD sensors.
Media Contact:
Emil Venere, (301) 975-5745
Materials
Tiny Particles Offer Big Benefits in Growing Market
Materials made of tiny particles (less than 100 billionths of a meter in size) are beginning to offer benefits in just about every type of product but the kitchen sink--from better sunblocks to ultra-durable armor and mechanical seals to faster industrial catalysts. And who knows, the kitchen sink could be next.
These "nanoscale" materials--long prized by scientists for their often superior chemical, mechanical, electronic, magnetic or optical properties--finally are finding their way into the commercial marketplace thanks to early co-funding for the development of basic processing technology from the National Institute of Standards and Technology's Advanced Technology Program.
The ATP project, which ended in 1995, enabled Nanophase Technologies Corp. of Burr Ridge, Ill., to achieve a 25,000-fold increase in production of the innovative metal, ceramic and composite materials and a 20,000-fold reduction in cost per gram. The company also demonstrated a process for shaping nanoscale ceramics into parts quickly and economically, without machining. The company began making commercial quantities of material in late 1996 and reported $2.24 million in sales for the first nine months of 1997.
The materials already are used in skin-care products and appear promising for use in semiconductor polishing slurries, ceramic armor and mechanical seals, industrial catalysts and other applications.
Media Contact:
Michael Baum, (301) 975-2763
Tech Trivia
The crash of the U.S. Navy dirigible Shenandoah in a thunderstorm in 1923 killed 14 people. The National Bureau of Standards (now NIST) conducted tests on Shenandoah's frame and found it had become brittle. Nevertheless, recommendations to strengthen alloy frames did not save the Golden Age of airships, which ended with the Hindenburg's crash in 1937.
The National Bureau of Standards (now NIST) determined that the collapse of the Silver Bridge which spanned the Ohio River and carried 46 motorists to their deaths in 1967 started with a single crack only 0.12 inches deep. The bridge collapse led to important developments in both federal highway inspection and metallurgical research procedures.
In 1981, National Bureau of Standards (now NIST) engineers determined that a change in the original design of hanger rods used in suspended walkways at the Hyatt-Regency Hotel in Kansas City, Mo., caused them to collapse during an afternoon tea dance, killing 113 people.
U.S. Department of
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Editor: Linda Joy
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Last update: August 28, 1998
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