Technology at a Glance is a quarterly newsletter from the National Institute of Standards and Technology reporting on research results, funding programs, and manufacturing extension and technology services. About Technology at a Glance.
physicist John Kitching with the world’s smallest atomic
© Geoffrey Wheeler
The heart of a minuscule atomic clock—believed to be 100 times smaller than any other atomic clock—has been demonstrated by NIST scientists, opening the door to atomically precise timekeeping in portable, battery-powered devices for secure wireless communications, more precise navigation and other applications.
Described in the Aug. 30, 2004, issue of Applied Physics Letters, the clock’s inner workings are about the size of a grain of rice (1.5 millimeters on a side and 4 millimeters high), consume less than 75 thousandths of a watt (enabling the clock to be operated on batteries) and are stable to one part in 10 billion, equivalent to gaining or losing just one second every 300 years. In addition, this “physics package” could be fabricated and assembled on semiconductor wafers using existing techniques for making micro-electro-mechanical systems (MEMS), offering the potential for low-cost mass production of an atomic clock about the size of a computer chip and permitting easy integration with other electronics. Eventually, the physics package will be integrated with an external oscillator and control circuitry into a finished clock about 1 cubic centimeter in size.
Atomic clocks long have provided the most accurate timekeeping but also have traditionally been large—up to two meters in height—as well as power-hungry and expensive to build.
“The real power of our technique is that we’re able to run the clock on so little electrical power that it could be battery operated and that it’s small enough to be easily incorporated into a cell phone or some other kind of handheld device,” says physicist John Kitching, principal investigator for the project. “And nothing else like it even comes close as far as being mass producible.”
Produced with funding from the Defense Advanced Research Projects Agency, the mini-clock is comparable in size and long-term stability to temperature-compensated quartz crystal oscillators, currently used in portable devices. NIST scientists expect to improve the clock’s long-term stability and reduce its power consumption to the point where the device could substantially improve the performance of many commercial and military systems that require precision time keeping.
For more information on the chip-scale clock, go to www.boulder.nist.gov/timefreq/ofm/smallclock/.
Contact: John Kitching, (303) 497-4083.
Computerized systems that automatically match fingerprints have become so sophisticated that the best of them are accurate more than 99 percent of the time, according to the most comprehensive known study of the systems ever conducted.
NIST computer scientists tested 34 commercially available systems provided by 18 companies from around the world. NIST conducted the study to fulfill requirements of the USA PATRIOT Act and the Enhanced Border Security and Visa Entry Reform Act.
The test used operational fingerprints from a variety of U.S. and state government sources. A total of 48,105 sets of fingerprints from 25,309 people, with a total of 393,370 distinct fingerprint images, were used to enable thorough testing.
The most accurate systems were from NEC of Japan, SAGEM of France and Cogent of the United States. The performance of these three systems was comparable. The performance varied depending on how many fingerprints from a given individual were being matched. The best system was accurate 98.6 percent of the time on single-finger tests, 99.6 percent of the time on two-finger tests, and 99.9 percent of the time for tests involving four or more fingers. These accuracies were obtained for a false positive rate of 0.01 percent.
The Justice Management Division of the U.S. Department of Justice funded the study in connection with its efforts to integrate the fingerprint systems operated by the Federal Bureau of Investigation and the Department of Homeland Security.
NIST is publishing a series of reports on the testing that includes a comprehensive analysis of the results. The first of these reports is available at http://fpvte.nist.gov.
Wilson, (301) 975-2080.
|Flames from a mocked up house ignite a similar “house” 6 feet away.|
In a recent series of NIST full-scale laboratory experiments, it took less than five minutes for flames from a simulated house with combustible exterior walls to ignite a similar “house” six feet away.
The experiments were conducted at the NIST Large Fire Facility. These experiments, along with additional tests conducted with more fire-resistant structures, are part of a program to develop computer models for predicting the spread of fire in residential communities.
As land prices continue to rise, homes are being built closer together, many without fire-resistant materials. Building officials need information about the rate of fire spread in communities under various house spacings, construction methods and materials, and weather con-ditions. Fire departments also have to understand the time required for fire spread from one house to another in order to provide adequate response and resources.
Each experiment conducted at NIST involved two 16-foot structures clad in vinyl siding that simulated neighboring houses. The outside walls for each structure included windows. In the first experiment, typical home furnishings were ignited in one “home” and the fire spread was recorded, along with heat release rates and other data. In less than five minutes, flames shattered the window of the home with the original fire, spread across the gap, and ignited the exterior of the second structure.
The second experiment measured the effects of a fire-resistant barrier in the exterior wall. Flames from the first structure again reached the second structure in about four minutes, but this time, the gypsum barrier prevented the fire from significantly damaging the simulated home.
NIST plans to summarize its results once an analysis of the experiments is complete. Officials considering house separation regulations and/or the inclusion of fire-resistant barriers on exterior walls should find such fire spread data useful.
Contact: Alexander Maranghides, (301) 975-4886.
|Computer model of the complex crystal structure of the human protein cardiac troponin.|
Diagnosing heart attacks will become a more accurate science thanks to the first of a new series of NIST clinical standards. Human Cardiac Troponin Complex (Standard Reference Material 2921) will help manufacturers develop and calibrate assays that measure specific protein concentrations in patient blood samples to determine whether a heart attack has occurred.
The SRM is a solution containing certified concentrations of three related proteins, including cardiac troponin I, purified from human heart tissue from cadavers. Users can calibrate their assays by analyzing the SRM and comparing the results to the NIST-certified value for troponin I. The standard is expected to help reduce variations in clinical test results from as much as 50-fold on the same sample to just twofold.
NIST already produces more than 60 SRMs for the clinical diagnostics community, but this is the first one designed to help measure concentrations of large, protein-based health status markers. Troponin I is difficult to measure because it can exist in low concentrations and in different chemical forms, sometimes attached to other related proteins. NIST is developing additional standards and methods for measuring other health status indicators of this type, including hormones used to assess thyroid function, and other markers for heart attack risk such as homocysteine and C-reactive protein.
SRM 2921 is intended to help U.S. makers of in vitro diagnostic (IVD) medical devices sell their products in Europe. A European Union directive requires that such devices be calibrated with standards that are traceable to internationally recognized certified reference materials or procedures. SRM 2921 has been nominated for inclusion on the international list of higher order reference materials. The list currently contains approximately 150 entries for 96 health status markers; NIST SRMs provide traceability for 72 of these.
Contact: Michael Welch, (301) 975-3100.
|False color image of a condensate forming from pairs of fermion potassium atoms.|
Scientists at JILA, a joint laboratory of NIST and the University of Colorado at Boulder (CU-Boulder) report the first observation of a “fermionic condensate” formed from pairs of atoms in a gas, a long-sought, novel form of matter. Physicists hope that further research with such condensates eventually will help unlock the mysteries of high-temperature superconductivity, a phenomenon with the potential to improve energy efficiency dramatically across a broad range of applications.
The research is described in a paper published in Physical Review Letters. The new work complements a previous major achievement, creation of a “Bose-Einstein” condensate, which earned JILA scientists Eric Cornell and Carl Wieman the Nobel Prize in Physics in 2001.
Bose-Einstein condensates are collections of thousands of ultracold “boson” atoms occupying a single quantum state, that is, all the atoms are behaving identically like a single, huge superatom.
The new condensate is made with a different type of particle, fermions, that are inherently difficult to coax into a uniform quantum state.
Superconductivity, in which currents flow without resistance or losses, involves the pairing of electrons, which are also fermions. Quantum physicists are in a worldwide race to produce fermionic condensates from gases because they are expected to exhibit a “super-fluidity” similar to that seen in superconductors, but will be much easier to study.
“The strength of pairing in our fermionic condensate, adjusted for mass and density,” NIST Fellow Deborah Jin explains, “would correspond to a room temperature superconductor. This makes me optimistic that the fundamental physics we learn through fermionic condensates eventually will help others design more practical superconducting materials.”
For further details, see www.nist.gov/public_affairs/releases/fermi_condensate.htm.
NIST researchers have discovered that the addition of carbon nanotubes to a common commercial polymer, polypropylene, leads to dramatic changes in how the molten polymer flows. This process eliminates a widespread manufacturing headache known as “die-swell” in which polymers swell in undesirable directions when passing through the exit port of an extruder (a machine for producing more or less continuous lengths of plastic sections).
Researchers have been adding small amounts of nanotubes—tiny tubes of carbon about 1,000 times thinner than a human hair—to polypropylene in hopes of dramatically enhancing the material’s strength and other properties. Once improved, the polymer then could be processed at high speed through extruders for use in manufacturing.
NIST materials scientists were concerned that because nanotubes make the polypropylene rubbery, the material would be difficult to process or its enhanced properties would be lost. To their surprise, the opposite proved true. When sheared (forced) between two plates, the polymer normally separates the plates. However, when nanotubes are added, the plates are pulled together.
The scientists found that this “pulling together” completely alleviated die-swell. Industry currently uses various time-consuming trial-and-error solutions to deal with the problem.
die-swell should help manufacturers improve their time-to-market
plifying their die design proc-esses and enabling the manufacture of smaller components.
The NIST work appears in the August 2004 edition of the journal Nature Materials.
Contact: Kalman Migler, (301) 975-4876.
A pinch of iron dramatically boosts the cooling performance of a material considered key to the development of magnetic refrigerators, NIST researchers report in Nature. By adding a small amount of iron (about 1 percent by volume), the NIST team enhanced the effective cooling capacity of the so-called “giant magnetocaloric effect” material by 15 to 30 percent. The result “is a much-improved magnetic refrigerant for near-room-temperature applications.” The original material—a gadolinium-germanium-silicon alloy—already is considered an attractive candidate for a magnetic refrigerant. However, its cooling potential is undercut by significant energy costs exacted during the on-and-off cycling of an applied magnetic field, the process that drives the refrigeration device. The iron supplement nearly eliminates cycling inefficiencies. Magnetic refrigerators offer improved energy efficiency, lower operating costs, elimination of environmentally damaging coolants, and nearly noise- and vibration-free operation. Contact: Robert Shull, (301) 975-6035.
Body tissues such as blood vessels, cartilage, and skin—even whole organs such as kidneys, livers, and hearts—could become more widely available for transplants as a result of a patent issued recently to Organ Recovery Systems of Chicago. With support from NIST’s Advanced Technology Program and the National Institutes of Health, the company developed a method to chill body tissues and organs well below freezing without forming ice crystals. Organs and some tissues presently are stored for short periods at refrigerator temperatures but freezing has not been possible because ice crystals damage delicate cells and greatly reduce the viability or functions of the tissue. The company’s technique uses a mixture of “cryoprotectant” compounds that reduce ice formation and minimize toxicity, along with careful control of the cooling and warming processes to minimize damage to the tissue. Doctors conducted over 24,000 organ transplants in the United States in 2002; yet 16 people die each day waiting for an organ transplant. Better preservation techniques would allow transplant materials to be shipped anywhere in the world or, better yet, collected and stored in something akin to blood banks until needed. Contact: Kelvin Brockbank, (843) 514-6164, email@example.com.
NIST physicists have demonstrated “teleportation” by transferring key properties of one atom to another atom without using any physical link, according to results reported in the journal Nature. Unlike the “beaming” of actual physical objects and people between distant locations popularized in the Star Trek science fiction series, the term teleportation is how physicists describe a transfer of “quantum states” between separate atoms. The quantum state of an atom is a description of such things as its energy, motion, magnetic field, and other physical properties. The NIST experiments used laser beam manipulations to transfer quantum states of one beryllium atom to another atom within a set of microscale traps, with a 78 percent success rate. The technique may prove useful for transporting information in quantum computers of the future, which could use central processing elements smaller than a cube of sugar to carry out massively complex computations that are currently impossible. Teleportation could increase computing speed and efficiency by linking distant zones within a computer. Contact: David Wineland, firstname.lastname@example.org, (303) 497-5286.
Accurately measuring exactly what’s in the food we eat, before we eat it, is a surprisingly difficult job. NIST chemists hope to make the process easier and more accurate with Standard Reference Material (SRM) 1946, which is a set of five bottles of frozen, homogenized trout from Lake Superior. With carefully measured values for about 100 chemical constituents, the SRM will help food industry and environmental researchers assure that measurements of both healthful ingredients and contaminants in fish and similar foods are accurate. Labora- tories can validate their analytical methods and instrument performance by using them to analyze the SRM and comparing their results to the NIST values. This is the first NIST SRM with certified values for three of the more toxic varieties of polychlorinated biphenyls (PCBs) and it is the first food-matrix SRM with values for omega-3 fatty acids, which have been shown to reduce the risk of cardiovascular disease. It also is certified for methylmercury, a neurotoxin found in fish that has prompted federal advisories to warn pregnant women against eating certain fish. Contact: Michele Schantz, (301) 975-3106.
Digital Evidence—Criminal investigators increasingly find that personal computers, handheld devices, and even mobile phones contain pictures, e-mail, and other data critical to the prosecution of cases. A new guide written by computer forensics experts under the direction of the NIST Office of Law Enforcement Standards provides step-by-step instructions to assist investigators in locating digital evidence so that it stands up to scrutiny once cases are tried. Requested by the National Institute of Justice, the guide is based on the collective experience of a panel of computer forensics experts. NIST staff then organized the information into an easily understood, user friendly document. Contact: Susan Ballou, (301) 975-8750.
AIDS Database—NIST and the National Cancer Institute have developed an online database of AIDS-related protein structures. The HIV Structural Reference Database (http://xpdb.nist.gov/hivsdb/hivsdb.html) distributes structural data for proteins involved in making HIV, the virus that causes AIDS, as well as molecules that inhibit these activities. By providing data standards, interoperability between sources, and user-friendly search tools, the NIST/NCI database will help researchers who are developing AIDS drug treatments or studying the disease itself to obtain rapid and reliable information on drugs and their fragments. Contact: Talapady Bhat, (301) 975-5448.
Supply Chain Standards—Inadequacies in managing product description, purchase order, inventory, scheduling, and accounting information cost the automotive and electronics industries a combined total of almost $9 billion annually, according to a newly released study commissioned by NIST. Almost all of these costs could be eliminated with optimally integrated systems for exchanging information throughout supply chains, the study concludes. Conducted by RTI International, the analysis found that only a handful of firms are close to achieving “ideal” information integration with supply chain partners. One notable problem is the lack of universally accepted and implemented standards for the format and content of messages that flow between supply chain partners. Contact: Gregory Tassey, (301) 975-2663.
NIST is an agency of the US Department of Commerce's Technology Administration. NIST develops and promotes measurement, standards, and technology to enhance productivity, facilitate trade, and improve the quality of life. Technology at a Glance is produced by Public and Business Affairs, NIST, 100 Bureau Dr., Stop 1070, Gaithersburg, Md. 20899-1070. Any mention of commercial products is for information only; it does not imply recommendation or endorsement by NIST. Technology at a Glance Editor: Gail Porter, (301) 975-3392, email: email@example.com. For patent information, call (301) 975-3084.