NIST Tech Beat - December 21, 2006

What does the Library of Congress (LOC) do when it wants to preserve a 500-year-old map, the only known copy of the first world map to call America “America?” To preserve the document sometimes called “America’s Birth Certificate,” the Library has partnered with the National Institute of Standards and Technology (NIST) to design a hermetically sealed encasement for the 12-sheet 1507 Waldseemüller map. The encasement is designed to provide optimum accessibility for the public while preserving and securing the document. NIST will supervise the construction of the case, which will be turned over to the Library in 2007. The Library will display the map in the fall of 2007 as part of its “New Visitors’ Experience” exhibit.

NIST designed and built the encasements that today house America’s Charters of Freedom—the Declaration of Independence, the Constitution, the Bill of Rights and their transmittal letters—for the National Archives in 2003. The Waldseemüller map encasement would be almost six times bigger than the largest previous case (for the Bill of Rights).

The planned NIST/Library design calls for the case to be machined from a solid piece of aluminum and sealed with an anodized aluminum frame and a sheet of laminated, non-reflective glass. The finished case will measure 116 in. by 73 in. by 4 in. (295 cm by 185 cm by 10 cm). The hermetically sealed encasement will include valves for flushing out oxygen (which chemically reacts and degrades organic material such as the map’s paper and ink) and filling the encasement with inert argon gas. The encasement also will contain monitoring devices to measure internal environmental conditions.

The design, fabrication and testing of the encasement are largely funded through the Waldseemüller Support Fund, established by Virginia Gray and the Gray Family in memory of Martin Gray, with additional support from The Alcoa Foundation, for the encasement fabrication and instrumentation, and the Alcoa Company, which will donate the monolithic aluminum blocks from which the various encasement components will be fabricated.

The Library of Congress acquired Waldseemüller’s 1507 world map in 2003 from the family of Prince Johannes Waldburg-Wolfegg of Wolfegg, Germany. The map was drawn by cartographer Martin Waldseemüller and others in St. Dié, France and depicts European geographic discoveries of the late 15th and early 16th centuries, including those based on data collected by Amerigo Vespucci during his voyages to America. Vespucci’s explorations, especially along the east coast of South America, convinced him that Columbus’ “Indies” was a new continent. In his map, Waldseemüller named the newly discovered continent “America” in Vespucci’s honor. Later cartographic efforts by Waldseemüller referred to the Western Hemisphere as “Terra Incognita” or “Terra Nova.” Too late—the first name had already caught on.

Researchers from the National Institute of Standards and Technology (NIST) and four universities have made the first experimental observation of rare particles of light emitted during the radioactive decay of the neutron, a key building block of matter. This work confirms theoretical predictions of this type of decay of the neutron and sets the stage for a new class of tests of basic theories in particle physics.

The neutron is stable only in the nucleus of a stable atom; a free neutron decays into other particles—a proton, electron and anti-neutrino—within about 15 minutes. This “neutron beta-decay” has been studied for decades without proof of the occasional photon (light) emissions predicted by theory.

“This measurement is difficult because the neutron lifetime is very long, so very few neutrons decay at one time, and of those that decay, very few emit a photon,” says NIST physicist Jeffrey Nico, lead author of the paper. “To make it even worse, the background radiation is very large.” The team, including researchers from NIST, Tulane University, the University of Michigan, the University of Maryland and the University of Sussex (Brighton, England) determined that, on average, slightly more than three out of 1,000 neutron decays produce a photon above an energy level that is relatively low but still observable. The measured value has only about 10 percent uncertainty, which is considered remarkable given that this decay had never been observed before.

The experiments, reported in the Dec. 21, 2006, issue of Nature*, were performed at the NIST Center for Neutron Research (NCNR) in Gaithersburg, Md., because of the unique instruments and expertise at the facility.

This successful experiment now makes it possible to design new tests of the “standard model” of particle physics and search for new physics beyond it, according to the paper. With future upgrades to the experimental set-up, the authors say they could enhance measurement precision further and open up additional opportunities for pushing the boundaries of scientific knowledge. Read more details of the experiments at www.nist.gov/public_affairs/releases/neutron_light.html.

The research was supported in part by the National Science Foundation and the U.S. Department of Energy.

*J.S. Nico, M.S. Dewey, T.R. Gentile, H.P. Mumm, A.K. Thompson, B.M. Fisher, I. Kremsky, F.E. Wietfeldt, T.E. Chupp, R.L. Cooper, E.J. Beise, K.G. Kiriluk, J. Byrne and K.J. Coakley. Observation of the radiative decay mode of the free neutron. Nature (Dec. 21, 2006).

What do you get when you superimpose a rotating pattern of intersecting laser beams on a spinning cloud of ultracold atoms in a thin gas? Pretty pictures, for one thing—but also a new method that could be used to simulate why and how defects arise in superconductors, important materials that are difficult to study directly.

By combining two cutting-edge laboratory creations—optical lattices and atoms in a Bose-Einstein condensate (BEC) spinning in a trap like planets orbiting the sun—physicists at JILA have developed a method of visualizing defects, or disruptions, in rotating patterns. The experiments, reported in a paper published online Dec. 12 by Physical Review Letters,* create the equivalent of “tornadoes in valleys,” says group leader Eric Cornell, a Fellow at the National Institute of Standards and Technology (NIST). JILA is a joint institute of NIST and the University of Colorado at Boulder.

A BEC is a unique form of matter, first created by Cornell and colleague Carl Wieman at JILA, in which atoms are chilled to near absolute zero, and a point at which, by the rules of quantum physics, they condense into an amorphous “super atom” in which the individual atoms are indistinguishable. Part of the scientific fascination with BECs is that they share important physical characteristics with seemingly quite different phenomena, such as low-energy paired electrons in superconductors or the “superfluid” helium-4 that flows uphill with zero viscosity. For instance, helium-4, when stirred, doesn’t circulate around the container like water in a glass, but rather breaks into an orderly array of quantized vortices, or little tornadoes. BECs behave the same way.

The JILA experiments were performed with 3 million rubidium atoms held in a magnetic trap. A superfluid of vortices was created by spinning the trap. The reddish BEC cloud, about 100 micrometers in diameter, contained about 100 hollow vortices, like a spinning bundle of fibers. Lasers were used to set up optical lattices—grids of light in an arrangement of energy peaks and troughs—in triangular and square patterns and focus them onto the BEC.

The overlapping lattice and vortices, under certain conditions such as when spinning at about the same rates, tend to lock together. The energy peaks of the lattice “pin” the BEC at those spots by reducing the density of the superfluid flowing around the local vortex. The JILA group visualized the structure or repeating patterns of the pinned vortex lattice by taking pictures over time, and then using an image processing technique to show how the vortex lattice structure and orientation were related to the optical lattice structure and orientation. The vortex lattice and peak optical signals evolve into different shapes at various laser intensities and spinning rates. Because BECs and optical lattices can be precisely controlled, the technique may be useful in studying more mysterious patterned superfluids, such as superconductors.

* S. Tung, V. Schweikhard and E.A. Cornell. 2006. Observation of vortex pinning in Bose-Einstein condensates. Physical Review Letters. 97, 240402 (2006) Posted online Dec. 12.

Before carbon nanotubes can fulfill their promise as ultrastrong fibers, electrical wires in molecular devices, or hydrogen storage components for fuel cells, better methods are needed for purifying raw nanotube materials. Researchers at the National Institute of Standards and Technology (NIST) and the National Renewable Energy Laboratory (NREL, Golden, Colo.), have taken a step toward this goal by demonstrating a simple method of cleaning nanotubes by zapping them with carefully calibrated laser pulses.

When carbon nanotubes—the cylindrical form of the fullerene family—are synthesized by any of several processes, a significant amount of contaminants such as soot, graphite and other impurities also is formed. Purifying the product is an important issue for commercial application of nanotubes. In a forthcoming issue of Chemical Physics Letters*, the NIST/NREL team describes how pulses from an excimer laser greatly reduce the amount of carbon impurities in a sample of bulk carbon single-walled nanotubes, without destroying tubes. Both visual examination and quantitative measurements of material structure and composition verify that the resulting sample is “cleaner.” The exact cleaning process may need to be slightly modified depending on how the nanotubes are made, the authors note. But the general approach is simpler and less costly than conventional “wet chemistry” processes, which can damage the tubes and also require removal of solvents afterwards.

“Controlling and determining tube type is sort of the holy grail right now with carbon nanotubes. Purity is a key variable,” says NIST physicist John Lehman, who leads the research. “Over the last 15 years there’s been lots of promise, but when you buy some material you realize that a good percentage of it is not quite what you hoped. Anyone who thinks they’re going into business with nanotubes will realize that purification is an important—and expensive—step. There is a lot of work to be done.”

The new method is believed to work because, if properly tuned, the laser light transfers energy to the vibrations and rotations in carbon molecules in both the nanotubes and contaminants. The nanotubes, however, are more stable, so most of the energy is transferred to the impurities, which then react readily with oxygen or ozone in the surrounding air and are eliminated. Success was measured by examining the energy profiles of the light scattered by the bulk nanotube sample after exposure to different excimer laser conditions. Each form of carbon produces a different signature. Changes in the light energy as the sample was exposed to higher laser power indicated a reduction in impurities. Before-and-after electron micrographs visually confirmed the initial presence of impurities (i.e., material that did not appear rope-like) as well as a darkening of the nanotubes post-treatment, suggesting less soot and increased porosity.

The researchers developed the new method while looking for quantitative methods for evaluating laser damage to nanotube coatings for next-generation NIST standards for optical power measurements (see http://www.nist.gov/public_affairs/techbeat/tb2005_0126.htm#laser). The responsivity of a prototype NIST standard increased 5 percent after the nanotube coating was cleaned.

Researchers from the National Institute of Standards and Technology (NIST), the Naval Research Laboratory (NRL) and the University of Maryland (UMD) have demonstrated a deceptively simple technique for chemically bonding single strands of DNA to gold. Among other features, they report in a forthcoming issue* of the Proceedings of the National Academy of Sciences, the technique offers a convenient way to control the density of the DNA strands on the substrate, which could be important for optimizing DNA sensor arrays.

Short DNA sequences arrayed on substrates like glass, silicon or gold are used in biochemical sensors that can detect specific “target” sequences of DNA or analyze complex sequences. In such arrays, DNA strands are attached to the substrate by one end and stand up like bristles on a brush. Specific “target” DNA sequences from a test sample can be identified because they will bond (hybridize) only to a complementary sequence on the array—microarray “gene chips” are the best-known example of the technology. The properties of gold are well-known, so it is a practicaland convenient substrate for some sensors. One popular technique for making DNA sensors (developed at NIST) is to use DNA with a sulfur atom attached to one end, which acts as “glue” because sulfur readily reacts with gold.

But a potentially less expensive and even simpler approach, according to the NIST, NRL and UMD team, might be to use a string of adenine nucleotides as an anchor. Of the four nucleotides that comprise DNA molecules, adenine, turns out to have a particularly high affinity for gold. Short strands composed entirely of adenine will adhere to a gold surface even if they have to muscle aside other strands in the process. As a result, say the researchers, short blocks of adenine at the end of DNA strands can serve as bonding anchors—but even better, they say, these adenine blocks can be used to control the spacing of the DNA strands on the substrate. This is because each adenine tail lies flat on the substrate, taking up space. Within limits, the longer the adenine tail is, the larger is its footprint on the substrate, and the lower the total density of DNA strands.

Controlling the density of DNA “brushes” on a substrate is important for sensor design because an overly dense thicket does not leave enough room for “target” DNA strands from the test sample to bond, while too sparse an array doesn’t produce a strong enough signal.

The authors have applied for a patent on the technique. The research was supported by Office of Naval Research and the Air Force Office of Scientific Research.

*A. Opdahl, D. Petrovykh, H. Kimura-Suda, M.J. Tarlov and L.J. Whitman. Independent control of grafting density and conformation of single-stranded DNA brushes. Proceedings of the National Academy of Sciences, 104:9-14 (2007) (Appears on-line in PNAS Early Edition.)

The National Institute of Standards and Technology (NIST) has issued a revised version of Recommended Security Controls for Federal Information Systems (NIST Special Publication 800-53). First issued in February 2005, SP 800-53 is one of the key standards and guidelines developed by NIST to help federal agencies improve their information technology security and comply with the Federal Information Security Management Act (FISMA).

The publication recommends management, operational and technical controls needed to protect the confidentiality, integrity and availability of federal information systems. The controls are organized into 17 families, including risk assessment, contingency planning, access control and incident response. The changes focus on clarifying the security controls, eliminating redundancies and expanding supplemental guidance. Specific changes include: expanded information on the media protection family to address powerful, highly mobile processing and storage devices; new concepts to promote more cost-effective assessments, extend the life of security accreditations over time and reduce the paperwork associated with reaccreditations; and a more thorough discussion of the implications and risks of using external information system services and service providers.

The Baldrige Performance Excellence Criteria are the basis for a Baldrige Award application, but in addition, thousands of organizations use them to assess their performance, guide improvements and create a culture of excellence. The criteria include more than 200 questions in seven areas: leadership; strategic planning; customer and market focus; measurement, analysis and knowledge management; workforce focus; process management; and results. “While the questions are straightforward, they are designed to be thought provoking. Answering many of the questions will be challenging, but will help an organization identify its strengths and opportunities for improvement,” said Harry Hertz, director of the Baldrige National Quality Program.

The 2007 criteria include new questions to address four areas of growing importance: capitalizing on core competencies to build on strategic advantages; using innovation to improve all aspects of an organization; involving the workforce and external contributors, such as partners and an organization’s supply chain, to make critical work system decisions; and developing a high-performing workforce.

The 2007 Baldrige performance excellence criteria for business currently are available, and editions for education and health care will be available soon. The criteria are available at www.baldrige.nist.gov or by calling (301) 975-2036.

If you have done an Internet search, bought anything from a Web site or subscribed to a news alert service, chances are you used a special computer document language called XML. Similar to HTML, which is used to format web pages, XML allows computers to exchange information and act on it. Rules called schemas that stipulate precisely the type of information included in the document and how to handle it are critical to XML communication. Every month thousands of new schemas are introduced. Not all of them, however, are precise enough to transmit the needed information without misunderstandings.

Computer scientists at the National Institute of Standards and Technology (NIST) hope to avoid interoperability problems caused by poorly designed or imprecise schemas. The NIST engineers have just released a tool to help others develop well thought out schemas that are easy to understand, implement, maintain and expand. The test site contains sets of design rules for schemas as well as tests for the rules. Visitors to the site can use the rules to check whether a schema that they are developing or using meets good XML communication guidelines. Computer engineers skilled in XML are also encouraged to use the site to share their own rules with others in the XML community.

The National Institute of Standards and Technology (NIST) is seeking participants for its upcoming Text Retrieval Conference—TREC 2007. Since 1992, TREC has been fostering research to enable more powerful, faster and easier-to-use technologies for information retrieval. TREC 2007 will focus on seven tracks—including a blog track, to explore information seeking behavior in the blogosphere, and a legal track to develop search technology to help the legal profession find information pertinent to a case in digital document collections. For each TREC, NIST provides a test set of documents and questions. Participants run their own retrieval systems on the data and return to NIST a list of the retrieved top-ranked documents. NIST pools the individual results, judges the retrieved documents for correctness, and evaluates the results. The TREC cycle ends with a workshop in November that is a forum for participants to share their experiences. Organizations wishing to participate must submit an application by Feb. 20, 2007. For more information, see http://trec.nist.gov/call07.html.

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Editor: Michael Baum

Date created: December 21, 2006
Date updated: December 21, 2006
Contact: inquiries@nist.gov