NIST Tech Beat - Dec. 21, 2005

Albert Einstein was correct in his prediction that E=mc², according to scientists at the Massachusetts Institute of Technology (MIT), the Commerce Department’s National Institute of Standards and Technology (NIST), and the Institute Laue Langevin, Genoble, France (ILL) who conducted the most precise direct test ever of what is perhaps the most famous formula in science.

In experiments described in the Dec. 22, 2005, issue of Nature,* the researchers added to a catalog of confirmations that matter and energy are related in a precise way. Specifically, energy (E) equals mass (m) times the square of the speed of light (c²), a prediction of Einstein’s theory of special relativity. By comparing NIST/ILL measurements of energy emitted by silicon and sulfur atoms and MIT measurements of the mass of the same atoms, the scientists found that E differs from mc² by at most 0.0000004, or four-tenths of 1 part in 1 million. This result is “consistent with equality” and is 55 times more accurate than the previous best direct test of Einstein’s formula, according to the paper.

Such tests are important because special relativity is a central principle of modern physics and the basis for many scientific experiments as well as common instruments like the global positioning system. Other researchers have performed more complicated tests of special relativity that imply closer agreement between E and mc² than the MIT/NIST/ILL work, but additional assumptions are required to interpret their results, making these previous tests arguably less direct.

The Nature paper describes two very different precision measurements, one done at MIT by a group led by David Pritchard and another done at the ILL by a NIST/ILL collaboration led by the late physicist Richard Deslattes (NIST) and Hans Börner (ILL). Deslattes and his collaborators developed methods for using optical and X-ray interferometry—the study of interference patterns created by electromagnetic waves—to precisely determine the spacing of atoms in a silicon crystal, and for using such calibrated crystals to measure and establish more accurate standards for the very short wavelengths characteristic of highly energetic X-ray and gamma ray radiation. Börner and his collaborators were responsible for a highly successful gamma-ray measurement program at the ILL.

Enjoy New Year's Eve a Second Longer!

Y ou can toot your New Year's horn an extra second this year, say physicists at the National Institute of Standards and Technology (NIST). Along with the rest of the world's atomic timekeepers, NIST's time and frequency experts will insert a second (known as a leap second) into their time scale on Dec. 31 for the first time in seven years.

From 1972 (when the world went to the current system of atomic timekeeping) until Dec. 31, 1998, 22 seconds were added to Coordinated Universal Time (the official world time known as UTC) to keep it in sync with the Earth's rotation (which can speed up or slow down due to many factors). Since 1999 until recently, that rotation and UTC had stayed closely enough in harmony to not require the adjustment of adding a leap second.

This year's leap second will be implemented by adding an extra second to atomic clocks at NIST in Boulder, Colo., and other sites around the world. Normally, the last second of the year would be 23:59:59 UTC on Dec. 31, 2005, while the first second of the new year would be 00:00:00 UTC on Jan. 1, 2006. The leap second will be added at 23:59:59 UTC (06:59:59 p.m. Eastern Standard Time) on Dec. 31, so that atomic clocks will read 23:59:60 UTC before changing to all zeros.

A recent proposal to eliminate leap seconds altogether in the future is still under consideration by the international bodies in charge of coordinating world time.

For more information on leap seconds, go to http://tf.nist.gov/timefreq/general/leaps.htm.

Media Contact:
Michael E. Newman, michael.newman@nist.gov, (301) 975-3025

Scientists Solve Mystery of the 'Unicorn' Whale

Once the subject of mythical accounts of magical power, the helix-shaped tusk of the narwhal, or “unicorn” whale has proved to be an extraordinary sensory organ, according to a team of researchers from Harvard University, the Smithsonian Institution, and the Paffenbarger Research Center of the American Dental Association Foundation (ADAF) at the National Institute of Standards and Technology (NIST). The team's results were presented Dec. 13 at a technical conference in San Diego.*

Measuring up to 2.7 meters or about 9 feet long, the tusk is traversed by up to 10 million nerve pathways. These pathways connect the outside of the tusk to a central core of nerves leading to the animal’s brain. Based on experiments with samples of the tusk as well as with a captured narwhal whale, the research team found that the tusk’s sensory system may be capable of detecting changes in temperature, pressure, salinity and other factors that may help a narwhal survive its Arctic environment.

Working at NIST, Naomi Eidelman, Anthony Giuseppetti and Frederick Eichmiller of the ADAF examined samples of narwhal tusk with both infrared microspectroscopy and scanning electron microscopy. Their work revealed the tusk’s unusual structure.

While most mammalian teeth are softer on the inside and harder on the outside, narwhal tusk appears to be made “inside out,” says Eichmiller. The researchers believe the softer outer layers of the tusk may act like a shock absorber to help prevent breaks.

The project was funded by NIST, ADAF, Harvard School of Dental Medicine, National Geographic Society, Sunstar Butler, Smithsonian Institution Center for Arctic Studies, Astro-Med Inc., and the Federal Department of Fisheries and Oceans, Canada.

*M.T. Nweeia, N. Eidelman, F.C. Eichmiller, A.A. Giuseppetti, Y.G. Jung, Y. Zhang, "Hydrodynamic sensor capabilities and structural resilience of the male narwhal tusk," 16th Biennial Conference on the Biology of Marine Mammals, Dec. 13, 2005, San Diego, CA.

Evaluation Metrics Proposed for Firefighter Thermal Imagers

Firefighters are starting to recognize the potential usefulness of thermal imagers or infrared cameras for saving property and lives. Choosing the most appropriate thermal imager for a particular use, however, can be difficult. No standardized performance guidelines exist for infrared camera devices specifically tailored to first responder needs. For example, the devices may be used to locate victims in a burning building or to pinpoint fire sources in a smoky environment.

Researchers at the National Institute of Standards and Technology (NIST) hope to change that situation. Last month they submitted recommendations to the National Fire Protection Association (NFPA) that outline evaluation methods for thermal imagers as used in six critical emergency situations. These recommendations include tests to assess durability as well as image quality.

While firefighter applications represent less than 10 percent of the $1.2 billion worldwide annual market for infrared cameras, the NIST researchers say that the performance evaluation methods will be very important to the first responder community. “Right now," says Francine Amon, leader of the NIST team, “fire departments have to base their thermal imager purchasing decisions on manufacturer’s literature, personal experience and word-of-mouth recommendations. Standardized performance metrics and test methods should improve the selection process for these potentially life-saving devices that cost an average of $10,000 each. They also should encourage technological innovation for the first responder community.”

The NIST researchers suggest performance metrics that would reveal a thermal camera’s ability to (1) detect unusually hot spots, such as electrical outlets and light ballasts; (2) guide fire hose streams toward the fire source; (3) “size-up” thermal conditions inside a building, such as hot walls or ceiling sections, in preparation for entry into a room; (4) identify faces and bodies of firefighters and victims for search and rescue operations; (5) find hot spots and hidden smoldering during reconnaissance in the aftermath of a fire; and (6) locate hazardous material spills. The NFPA’s Committee on Emergency Service Electronic Safety Equipment is expected to review the suggestions in 2006.

In addition to NIST, the Department of Homeland Security (DHS) and the United States Fire Administration (USFA) are providing funding for NIST’s ongoing thermal imaging performance evaluation project. NIST, DHS and USFA recently sponsored a workshop at NIST on “Thermal Imaging Research Needs for First Responders.” A copy of the proceedings is available at http://www.fire.nist.gov/. A USFA Web site discussing the project is available at www.usfa.fema.gov/research/safety/nist3.shtm.

After three years of development, the National Institute of Standards and Technology (NIST) has released a major upgrade of the widely used NIST/EPA/NIH Mass Spectral Library.

The library is an encyclopedic database of “fingerprints” used to identify chemical compounds with a technique called mass spectrometry. The method uses the unique masses of molecules to identify unknown chemicals. Samples are first vaporized, then ionized by stripping away one or more electrons, leading to fragmentation. These fragments are finally sorted by their mass-to-charge ratios using magnetic or electric fields, producing a “mass spectrum.” Even a sample of a pure element generally produces a spectrum with several peaks representing a unique distribution of masses due to isotopes with varying numbers of neutrons.

The new edition of the library, NIST 05, adds approximately 20,000 new spectra, bringing the total number of compounds found in the database to more than 163,000. Each spectrum has been analyzed and critically evaluated to ensure that the library has the best possible current data.

The upgraded library also includes two important new classes of chemical reference data. Gas-phase “retention index” data—used in gas chromatography to identify volatile organic compounds—have been added for more than 25,000 different compounds. And a separate collection of more than 2,000 tandem mass spectrometry (MS/MS) spectra has been added. MS/MS spectra arise from a process where the ionization and fragmentation steps are separated. They have become widely used “fingerprints" for compounds in complex biological samples in fields such as proteomics and metabolomics. This is the first evaluated, general purpose MS/MS data library available to the general public.

Produced in collaboration with the Environmental Protection Agency and the National Institutes of Health, the NIST 05 library is available with Version 2.0d of the NIST MS Search Program for Windows through authorized dealers. Details are available from the NIST Standard Reference Data Program at www.nist.gov/srd/nist1a.htm.

Researchers at the National Institute of Standards and Technology (NIST) have published an interesting study that sheds light on the fate of a familiar pharmaceutical as it enters the waste stream. In work initially described in NIST TechBeat last year, NIST chemists investigated probable chemical reactions involving acetaminophen when the drug is subjected to typical wastewater processing. Acetaminophen is the most widely used pain reliever in the United States, and a study of 139 streams by the U.S. Geological Survey found that it was one of the most frequently detected man-made chemicals.

The scientists found that the drug readily reacts in chlorine disinfection to form at least 11 new products, at least two of which are known to be toxic. The results, according to lead author Mary Bedner, demonstrate that environmental scientists need to be concerned about downstream reaction products as well as the original waste materials. “The issue is what you should be looking for in the environment,” she says. “When you are looking for the effects of pharmaceuticals in the environment, you need to ask what they’re going to turn into.”

The full paper, “Transformation of Acetaminophen by Chlorination Produces the Toxicants 1,4-Benzoquinone and N-Acetyl-p-benzoquinone Imine” will appear in Environmental Science and Technology, and is available from the journal’s ASAP Web site http://pubs.acs.org/journals/esthag/index.html.

The National Institute of Standards and Technology (NIST) will co-host a workshop to discuss needed measurement technologies and standards in the rapidly evolving field of nanoscale biotechnology at Rice University (Houston, Texas) on Jan. 19, 2006.

The convergence of nanotechnology—with its focus on synthesizing materials and devices, and controlling their properties on an atomic scale—and biotechnology has opened up a broad landscape of potential applications and issues in medicine, basic research, manufacturing, and materials science. Nanoparticles and nano-structured materials are being studied for new methods of drug delivery and targeting therapeutic agents, for improving contrast and detection levels in medical imaging, and for basic research on the structure and dynamics of biomolecules. Manufacturers studying nanotechnologies are concerned with basic issues of safe materials handling and scale-up.

The January workshop will seek to identify the most critical measurement and standards needs in this diverse and important new area of technology. The U.S. Measurement System (USMS) Workshop on Measurement and Standards Needs in NanoBiotechnology is sponsored by NIST, The Alliance for NanoHealth, Battelle, Richard E. Smalley Institute for Nanoscale Science and Technology (Rice), Center for Nanoscale Science and Technology (Rice), the departments of Defense and Energy, BioHouston, Environmental Protection Agency, ASTM International, Gulf Coast Consortium, Food and Drug Administration, Office of Naval Research, National Cancer Institute, Nanotechnology Characterization Laboratory (NCI), and Ben Franklin Technology Partners of Pennsylvania.

The workshop is one of a series on the U.S. Measurement System (USMS) sponsored by NIST to assess and document the nation's priority measurement and measurement-related standards needs for technological innovation, U.S. industrial competitiveness, safety and security, and quality of life.