At A Glance, Spring/Summer 1996
|Extension Program Success Stories||An Ultra-accurate Electron Counter|
|'Sounding' Out Improved Materials||Schroedinger's Cat in an Atomic Cage|
|X-ray Sensor Casts Better Blades||Revamped Website Offers Cool Stuff|
NIST's Manufacturing Extension Partnership, now in its seventh year of operation, has been steadily adding new centers to help the nation's smaller manufacturers get the technology and business advice they need to stay competitive. The program manages a network of about 60 centers in 42 states and Puerto Rico.
A new set of more than 50 case studies helps illustrate how the centers -- which are co-funded by NIST with state and local organizations -- provide services that help client companies modernize their operations, improve quality, and increase profitability. Examples of typical benefits reaped by small companies with assistance from their local MEP centers are:
To receive a packet of MEP success stories, contact MEP, (301) 975-5020.
After several years of concerted research, NIST is now the proud owner of the world's most accurate electron counter. An outgrowth of NIST's work to find better ways to determine capacitance (a measure of a capacitor's charge-holding ability), the counter can place 70 million electrons on a capacitor with an uncertainty of just one electron.
The heart of the counter is a special microcircuit that "pumps" electrons one at a time to a capacitor. In the atomic force micrograph above, the bullet-shaped regions in the center are micrometer-sized islands of aluminum, separated by tiny "tunnel junctions" of aluminum oxide (yellow dots). The capacitance of the islands is so small that at temperatures near absolute zero (less than 0.1 Kelvin) only one excess electron can occupy a given island at a time. An electron is moved from island to island through the tunnel junctions, which act like turnstiles allowing only one electron to get through at a time.
Reliable electron counting turns out to have several practical scientific benefits. By knowing exactly how many electron charges are placed on a capacitor and then carefully measuring the voltage, the NIST researchers will be able to measure capacitance directly. NIST's primary capacitance standard -- as required by the current international definitions of electrical quantities -- is a mechanical device. The availability of a very accurate measure of capacitance based on fundamental, "intrinsic" quantities should allow high-tech companies and other research laboratories to increase greatly the accuracy of their electrical measurements.
The new counter also may help researchers improve determination of the "fine-structure constant," a key value needed to better test predictions of quantum electrodynamics and a "holy grail" for many physicists and metrologists. The fine-structure constant is an absolute physical quantity related to the strength of an atom's electromagnetic forces. It is to physics and metrology what pi is to spherical geometry -- the better you know it the more accurately you can calculate a whole range of other important quantities.
Contact: Mark Keller, (303) 497-5430.
An inexpensive acoustic wave transducer developed by NIST mechanical engineers soon may make it easier for researchers to decide if new composite materials or film coatings have the right mechanical properties for specific applications.
The transducer sends a pulsed sound wave through a test sample that is submerged in water. The speed of the reflected wave provides a measure of the material's elasticity (its ability to flex under stress), while the direction of the reflected wave provides details about crystal planes or defects within the material.
Current acoustic microscopes use "lenses" and may cost hundreds of thousands of dollars. The NIST device uses off-the-shelf parts costing less than $20,000, yet can provide similar information about materials' properties. Rather than use a lens, the NIST instrument uses a curved transducer made with an inexpensive piezoelectric, plastic film. Electrical signals cause the film to emit relatively low frequency, pulsed sound waves. The curvature of the film focuses the sound waves in the same way that curved mirrors are used in telescopes to focus light from distant stars. The transducer is positioned above the sample and then scanned or rotated through different angles to get a full picture of the material's elastic properties.
The graphic above shows a composite image made by rotating the transducer above a sample of single-crystal silicon. The broken "V" wavefront is characteristic of silicon's cubic crystalline planes. The technique also will allow researchers to spot surface and subsurface defects in a variety of metallic or composite materials. One particularly promising application may be the inspection of novel films such as ceramic coatings on metal to predict their reliability under various conditions.
Contact: Nelson Hsu, (301) 975-6630.
They say, "You can't be in two places at one time." They may be wrong, however. NIST scientists have succeeded in preparing a beryllium atom that is simultaneously located in two widely separated places.
The feat was accomplished by cooling a single beryllium ion (with one of its two outer electrons stripped away) to almost absolute zero in an electromagnetic trap and then coaxing it into two distinct internal quantum states at the same time. While others have observed atoms in "super-imposed" internal quantum states, the NIST researchers went one better by delicately applying laser pulses to physically separate the two states by more than 80 nanometers, or 11 times the size of the original ion.
The graphic above shows an idealized view of the atom's positions. Each colored strip in the graphic represents a particular snapshot in time. It's like having a marble that is somehow simultaneously on opposite slopes of a bowl. The atom starts out in two widely separated places at the same time (two blue peaks in foreground). As time progresses, it moves "through itself" to the bottom of the "bowl" (red peaks), then splits to return to opposite sides of the "bowl."
In 1935 both Albert Einstein and Erwin Schroedinger described scenarios like the NIST experiment that are predicted in quantum mechanics but seem to defy reality. Schroedinger, for example, considered the possibility that a cat could somehow be prepared to be both dead and alive at the same time. "Schroedinger's cat" soon became shorthand for superimposed quantum states.
The NIST team verified that the cat state was produced by repeating their experiment many times while varying the direction the laser pulses gently push the two states apart. For certain directions, the researchers detected an interference pattern -- a series of bright and dark lines showing that the ion's wave (all atoms are both particles and waves) was actually superimposed on itself rather than flipping from one location to another. Widely separated states produced narrower interference lines than more closely spaced states. The effect is similar to shining a flashlight through a piece of cardboard with cut-out slits. Widely spaced slits produce a different interference pattern than closely spaced ones.
The NIST researchers hope their work will lead to better atomic clocks. It also may be useful in development of quantum computers and quantum cryptography.
Contact: Chris Monroe, (303) 497-7415.
Manufacturers of jet turbine blades often can't tell if a blade has been "cooked" right until they remove the mold and take a look.
Working in collaboration with engineers at Howmet Corp., Whitehall, Mich., NIST researchers have developed an X-ray sensor that they hope will take some of the guess work out of turbine blade technology. The instrument sends high-energy X-rays through a casting mold while a part is being made. By detecting the diffraction (change in direction) of the X-rays on the other side of the mold, the researchers can monitor in real-time the solidification of a molten metal into its crystalline state.
Ordinary solid metal objects contain a crazy quilt of crystals that grew at many different angles. Turbine blades, on the other hand, are often solidified in special "temperature gradient" furnaces that cool the molten alloy down slowly enough so that a single crystal grows from one end of the blade to the other. The lack of crystal boundaries makes these single-crystal turbine blades stronger and more resistant to high engine temperatures. The graphics above show the X-ray diffraction patterns produced with multicrystalline metal at room temperature (far left); liquid, non-crystalline molten metal (center); and a fully re-solidified crystal.
The NIST system should allow manufacturers to optimize their processes so that they consistently grow single-crystal blades in the shortest amount of time.
Contact: Thomas Siewert, (303) 497-3523.
NIST's homepage on the World Wide Web -- http://www. nist.gov -- got a facelift recently. The site was redesigned and several new sections were added. Specific NIST programs also have been improving their WWW pages. Some highlights:
NIST-developed software recently earned "two thumbs up" from a special
effects company that created scenes for Babe, the popular movie about a
talking pig. The movie won an Academy Award for visual effects that
included realistic computer-generated background scenes and simulations
of animal mouths talking. Rhythm & Hues Studios of Marina Del Rey,
Calif., cyber-crafted the scenes, then sent the massive graphics files
electronically to the film's Australian production site, 11,200
kilometers (7,000 miles) away. Rather than waste lots of staff time
monitoring every transfer, the company used a NIST software tool called
"Expect" to help watch the process and automatically resend scenes that
failed to make the trans-Pacific journey in one piece. The software
allows computer operators to write relatively simple programs that
recognize error messages, password prompts, or other recurring messages
and then perform the keystrokes a human operator would normally do next
to keep the process going. Systems administrators and others charged
with such repetitive computer chores commend the publicly available
software for simplifying and speeding hundreds of programming jobs and
computing applications. Contact: Don Libes, (301) 975-3535.
When the ball drops on Times Square to mark the start of the year 2000, NIST computer experts hope U.S. companies will be ready with computer hardware and software that uses 8-digit, yyyy/mm/dd, date codes rather than current 6-digit coding systems. The scope of the potential problems from 6-digit coding is enormous. An accounting system, for example, that assigns the year 2000 a date code of 00 may balk at printing checks that appear to have no assigned year. Electronic financial systems that transfer more than a trillion dollars a day may no longer work. Computer clocks will go haywire, unable to decide what date comes after no date. The cure for the problem, say NIST researchers, is for organizations to take steps now to assess how large a problem 6-digit date code formats will be for their particular organization, plan for the necessary modifications for custom-made software, and budget for replacement or upgrading of off-the-shelf software and hardware no later than 1999. This will allow enough time for testing and possibly debugging new systems before the critical day arrives. Contact: Gary Fisher, (301) 975-3275.
That's "GI" as in gastrointestinal, and the "bad guys" are viruses, disease-causing organisms, bile acids made from cholesterol, or other things in your digestive tract that you'd just as soon have keep passing through. GelTex Pharmaceuticals Inc., a 33-person company based in Waltham, Mass., has developed a polymer-based medicine designed to help the body rid itself of such gastro baddies before they have a chance to cause diarrhea, fat clogged arteries, and other unpleasantries. The company currently is conducting clinical trials with a capsule form of the medicine that selectively binds bile acids causing a decrease in LDL (bad) cholesterol and with another capsule that helps kidney dialysis patients maintain proper blood levels of phosphorus. With a three-year award from NIST's Advanced Technology Program, the company now is attempting to extend the technology to the treatment of human rotavirus, which causes diarrhea in infants and toddlers, and to Cryptosporidium parvum, a water-borne single-celled organism that caused 400,000 Milwaukee residents to become ill in 1993. The encapsulated polymer expands in the stomach into tiny molecular "nets" designed to bind only to a specific organism or molecule. The "nets" prevent the virus or organism from reproducing in the gastrointestinal tract and instead carry it through the intestines to be excreted. Contact: Amy Wilson, (617) 290-5888.
A NIST-developed machine called the "Super Shaker" could ironically help the world run a little more smoothly. Developed with funding from the U.S. Air Force, the new machine is designed to double the accuracy of NIST's current accelerometer calibrations. Accelerometers are electronic sensors that detect changes in speed and direction. They are used in aircraft and cars to sense changes in speed and in computer disk drives and cargo containers to measure vibration (i.e., man-handling during shipment). They also are key components for activating airbags, which inflate with rapid deceleration. NIST calibrates the reference accelerometers used by companies and research laboratories to check the accuracy of accelerometers in products. NIST is collaborating with Booth Development Inc., Short Beach, Conn., on the new automated machine. It can perform two types of calibrations previously requiring different machines and will operate over a wide range of frequencies. Contact: Beverly Payne, (301) 975-6639.
Radiation and Hearts--Balloon angioplasty has helped thousands of heart patients avoid bypass surgery. About one-third of the procedures have to be repeated, however, because the stretched artery walls scar and reclose. Tiny radioactive seeds made by Novoste Corp., Atlanta, may provide a way to limit such scarring. The seeds are delivered through a small catheter to the artery where they irradiate only the target artery wall. NIST physicists are developing ways to calibrate the radiation dose delivered by the seeds so that researchers can evaluate the value of the new therapy for angioplasty patients. Contact: Christopher Soares, (301) 975-5589.
Chip Measurements--Four companies and SEMATECH have joined NIST in a new consortium to develop the measurement instruments needed to pack more features into tomorrow's semiconductor chips. Corporate members include Bio-Rad Laboratories, Digital Instruments, KLA Instruments, and OSI. The Scanning Capacitance and Electromagnetic Sensor Consortium plans to research new ways to measure accurately the relative location or overlay of features placed on successive chip layers. Members will compare the merits of two new overlay measurement methods -- scanning capacitance probes and electromagnetic sensors. Contact: Michael Cresswell, (301) 975-2072.
Fat Content--To help ensure labels listing the fat content of foods are accurate, NIST has collaborated with the U.S. Department of Agriculture to prepare a new Standard Reference Material. The SRM consists of four 15-gram bottles of frozen blended food typically consumed in the United States. NIST chemists certified the concentrations of cholesterol and six of the most abundant fatty acids in the mixture. The new SRM also provides data for protein, moisture, total fat, ash, carbohydrate, and calories. Food laboratories can use the SRM to check the accuracy of their analysis instruments and methods. Contact: SRM Program, (301) 975-6776.
Aircraft Fires--The same technology that automobile manufacturers use
to inflate airbags soon may save lives and property as a fire
suppressant. NIST researchers believe that solid propellant gas
generators -- essentially airbag inflators without the bag -- have great
futures as compact, environmentally friendly fire suppressant systems.
Recent tests performed at the Naval Air Warfare Center in China Lake,
Calif., and Wright Laboratory in Dayton, Ohio, have demonstrated the
feasibility of using such systems to suppress simulated aircraft dry bay
fires. Other uses might be in warehouses, industrial sites, race cars,
and ships. Contact: Jiann Yang, (301) 975-6662.