NIST Tech Beat - May 28, 2008

Researchers working at the National Institute of Standards and Technology (NIST) have discovered that a new class of iron-based superconductors discovered earlier this year shares similar unusual magnetic properties with previously known high-temperature superconductors based on copper-oxide materials. The work announced today* on the Web site of the journal Nature emphasizes a critical but as yet unexplained link between magnetism and high-temperature superconductors.

The importance of magnetism to high-temperature (HTc) superconductors is remarkable because magnetism strongly interferes with conventional, low-temperature superconductors, but now may prove to be an integral element of HTc materials. These superconductors may one day enable energy and environmental gains by significantly improving the efficiency of electricity storage and transmission over long distances.

The team working at NIST, which included researchers from the University of Tennessee at Knoxville, Oak Ridge National Laboratory, the University of Maryland, Ames Laboratory, Iowa State University and the Beijing National Laboratory for Condensed Matter Physics, used neutron beams to demonstrate that, like copper-oxide superconductors, the new iron-based HTc materials discovered earlier this year by Japanese researchers share an unusual magnetic structure with magnetically active layers interspersed with layers of nonmagnetic material.

* C. de la Cruz, Q. Huang, J.W. Lynn, J. Li, W. Ratcliff II, J.L. Zarestky, H.A. Mook, G.F. Chen, J.L. Luo, N.L. Wang and P. Dai. Magnetic order close to superconductivity in the iron-based layered La(O_1-xF_x)FeAs systems. Nature Advanced Online Publication, May 28, 2008.

Researchers at the National Institute of Standards and Technology (NIST) have shown for the first time that a single layer of molecular “salve” can significantly soothe the stresses affecting clean metal surfaces. The discovery, revealed in a new paper,* may help scientists to understand the factors that influence surface stress, which is important in a broad array of applications from chemical and biological sensors to semiconductor manufacturing and metal plating.

Because the atoms on a clean metal surface are not bound on all sides, they are much more strongly bonded to each other than to the atoms beneath them. Atoms in a block of metal are like a big family, relaxed when surrounded by kinfolk. But when the metal is cut, the atoms exposed at the surface cling tighter to the siblings at their sides and draw closer together. That creates surface stress and causes the edges to curl and pull in toward the center of the surface.

Materials scientists generally believed that a single layer of molecules coating the surface would reduce the stress, but no tests had ever been performed to determine whether or not that actually happens. NIST researchers devised an elegant, highly sensitive experiment to measure the phenomenon using a 6-cm long, 0.3-cm wide and approximately 100-micron-thick gold-coated glass cantilever and a “salve” of mercaptobenzoic acid, a carbon-based sulfur-containing compound used for manufacturing such products as pharmaceuticals and agricultural chemicals. The “salve” forms a well-organized single layer (monolayer) on gold, and it forms a model system for measuring variations in surface stress. The team repeatedly deposited and removed the monolayer and monitored the curvature of the glass with a laser as the stress increased and decreased. The technique enabled them to record forces of less than 50 micronewtons per meter.

According to Chris Zangmeister, an author of the study, in addition to confirming that the application of a monolayer did reduce surface stresses, the team also discovered that the longer the molecules were allowed to sit the more comfortable they became with their new surroundings. As the monolayer became more comfortable, it became more stable, and the atoms in the metal began to adopt the molecules into the family, which substantially reduced the surface stresses.

The findings provide a deeper understanding of the forces at work at the interface of molecules and surfaces. Most notably the discovery could be used to create a new generation of chemical and biological sensors. Zangmeister says that these sensors would use molecular monolayers deposited on metal surfaces that are manufactured to react in the presence of chemical or biological agents in the environment. The activation of the monolayer would provide a proportional response to the amount of the substance it was designed to detect, which would result in a quantifiable decrease in the tension of the cantilever.

The findings appeared online in Electrochimica Acta in December and will appear as an invited paper in a special print issue of that same publication.

* C.D. Zangmeister, U. Bertocci, C.R. Beauchamp and G.R. Stafford. In situ stress measurements during the electrochemical adsorption/desorption of self-assembled monolayers. Electrochimica Acta. In press. The online version of the paper will be available until it is printed.

Researchers at the National Institute of Standards and Technology (NIST) have demonstrated a simpler and potentially lower-cost method for distributing strings of digits, or “keys,” for use in quantum cryptography, the most secure method of transmitting data. The new “quantum key distribution” (QKD) method, outlined in an upcoming paper,* minimizes the required number of detectors, by far the most costly components in quantum cryptography. Although this minimum-detector arrangement cuts transmission rates by half, the NIST system still works at broadband speeds, allowing, for example, real-time quantum encryption and decryption of webcam-quality video streams over an experimental quantum network.

In quantum cryptography, a recipient (named Bob) needs to measure a sequence of photons, or particles of light that are transmitted by a sender (named Alice). These photons have information encoded in their polarization, or direction of their electric field. In the most common polarization-based protocol, known as BB84, Bob uses four single-photon detectors, costing approximately $5,000-$20,000 each. One pair of detectors records photons with horizontal and vertical polarization, which could indicate 0 and 1 respectively. The other pair detects photons with “diagonal”, or +/- 45 degree, polarization in which the “northeast” and “northwest” directions alternatively denote 0 and 1.

In the new method, the researchers, led by NIST’s Xiao Tang, designed an optical component to make the diagonally polarized photons rotate by a further 45 degrees and arrive at the same detector but later, and into a separate “time bin”, than the horizontal/vertical polarized ones. Therefore, one pair of detectors can be used to record information from both kinds of polarized photons in succession, reducing the required number of detectors from four to two. In another protocol, called B92, the researchers reduced the required number of detectors from two to one. And in work performed since their new paper, the researchers further developed their approach so that the popular BB84 method now only requires one detector instead of four.

Although in theory quantum cryptography can transmit absolutely secure keys guaranteed by fundamental physical principles (measuring them will disturb their values and make an eavesdropper instantly known), the imperfect properties of photon detectors may undermine system security in practice. For example, photon detectors have an intrinsic problem known as “dead time,” in which a detector is out of commission for a short time after it records a photon, causing it to miss the bit of data that immediately follows; this could result in non-random (and therefore more predictable) bit patterns in which 0s alternate with 1s. Furthermore, inevitable performance differences between detector pairs can also cause them to record less random sequences of digits. The new design avoids these issues and maintains the security of quantum-key-distribution systems in practical applications.

* L. Ma, T. Chang, A. Mink, O. Slattery, B. Hershman and X. Tang. Experimental demonstration of a detection-time-bin-shift polarization encoding quantum key distribution system. IEEE Communications Letters Vol. 12, No. 6, June 2008. In press.

Information scientists announced an agreement last month on a “concept bank” programmers could use to build thinking machines that reason about complex problems at the frontiers of knowledge—from advanced manufacturing to biomedicine.

The agreement by ontologists—experts in word meanings and in using appropriate words to build actionable machine commands—outlined the critical functions of such a bank. It was reached at a two-day Ontology Summit held during NIST’s Interoperability Week in Gaithersburg, Md. The decision to create a unique Internet facility called the Open Ontology Repository (OOR) culminated more than three months of Internet discussion.

The ontology wordsmiths envision an electronic OOR in which diverse collections of concepts (ontologies) such as dictionaries, compendiums of medical terminology, and classifications of products, could be stored, retrieved, and connected to various bodies of information. OOR users, tasked with creating a computer program for manufacturing machines, for example, would be able to search multiple computer languages and formats for the unambiguous words and action commands. Plans call for OOR’s inventory to support the most advanced logic systems such as Resource Description Framework, Web Ontology Language and Common Logic, as well as standard Internet languages such as Extensible Markup Language (XML).

Steve Ray, NIST manufacturing systems integration chief who hosted the meeting, says, “The Ontology Summit established the critical set of requirements and ground rules needed before we can begin serious construction of the repository. It will save enormous amounts of time and money and facilitate new, complex systems in all sectors for manufacturing control, supply chain management, and even biomedical management systems.”

Key elements of the agreement include a review of the current state of the art in ontology repositories; the quality and gate-keeping criteria for registering and distributing the ontology material; and an infrastructure that allows reviews of diverse ontologies (an ontology of ontologies). The researchers pledged to continue work on the project via the Internet and expect to review their progress at next year’s NIST Interoperability Week conference.

If you love soccer but don’t want to wait until the next World Cup in 2010 to satisfy your appetite for the most popular game on Earth, the National Institute of Standards and Technology (NIST) has the answer—though the nourishment comes in very small bites.

Nanosoccer—the Lilliputian competition where computer-driven “nanobots” the size of dust mites challenge one another on fields no bigger than a grain of rice—will celebrate its first birthday this summer, and NIST is marking the anniversary with a new Web site at www.nist.gov/public_affairs/calmed/nanosoccer.html. Highlighting the site is a link to the recently produced video, “Bend It Like NIST: Tiny Soccer Players Pave Way for Microbots,” a 2-minute program that demonstrates how nanosoccer “road tests” agility, maneuverability, response to computer control and the ability to move objects—all skills that future miniaturized robot workers will need for tasks such as microsurgery within the human body or the manufacturing of atom-sized components for microscopic electronic devices.

The soccer nanobots are operated by remote control under an optical microscope. They move in response to changing magnetic fields or electrical signals transmitted across the microchip arena. Although the bots are a few tens of micrometers to a few hundred micrometers long, they are considered “nanoscale” because their masses range from a few nanograms to a few hundred nanograms. They are manufactured from materials such as aluminum, nickel, gold, silicon and chromium.

The new “NIST and Nanosoccer” Web site features summaries of the first two events in nanosoccer history: the July 2007 debut demonstration and competition at the international RoboCup in Atlanta, Ga., and the just-concluded demonstration at the RoboCup U.S. Open in Pittsburgh, Pa.

NIST jointly organized these “Nanogram League” events with RoboCup, an international organization dedicated to fostering innovations and advances in artificial intelligence and intelligent robotics by using the game of soccer as a testing ground. NIST’s goal in coordinating competitions between the world’s smallest robots is to show the feasibility and accessibility of technologies for fabricating MicroElectroMechanical Systems (MEMS), tiny mechanical devices built onto semiconductor chips and measured in micrometers (millionth of a meter).

Next up on the nanosoccer schedule is the first official Nanogram League competition for soccer nanobots at the July 2009 international RoboCup event in Austria. Academic institutions interested in organizing nanosoccer teams for the contest should contact Craig McGray, craig.mcgray@nist.gov, (301) 975-4110.

The National Institute of Standards and Technology (NIST) seeks grant proposals for the construction of science research buildings from institutions of higher education and nonprofit organizations. The agency announced on the Grants.gov Web site on May 20, 2008, that it will award approximately $29 million in congressionally directed funding for a special one-time competitive grant program. Awards are expected to range in size from approximately $10 million to $15 million.

The grant program was created under the Consolidated Appropriations Act of 2008 (P.L. 110-161) to provide funding for the construction of new buildings or the expansion of existing buildings for the sciences as they relate to the Department of Commerce and its agencies, which include NIST, the National Oceanic and Atmospheric Administration, and the National Telecommunications and Information Administration.

Grants will be made on a competitive basis to institutions of higher education and nonprofit organizations. Proposals will be evaluated by considering the scientific and technical merits of the proposal, the quality of the design of the proposed science research building, and the adequacy of a project execution plan that includes project scope, schedule, budget, management and financial support for the project. Selections also will be based on the degree to which the proposed project complements DoC science and technology programs; the applicant’s experience in promoting national impacts through research outcomes, training, cooperation with federal programs, and opportunities for visiting researchers; whether or not the proposed project would duplicate other federally funded projects; the amount of additional funding the applicant is prepared to supply; and other factors.

The deadline for applications is 3 p.m. ET, July 21, 2008. NIST expects to announce selections by the end of September 2008. The full announcement of the federal funding opportunity, with complete details on competition rules, evaluation criteria, selection process, eligibility, required forms and submission procedures, is available at www.grants.gov. In the right column, click “grant search” under Quick Links and search by CFDA number 11.615.

The National Institute of Standards and Technology (NIST) is seeking participants for its next Text Retrieval Conference—TREC 2008. TREC is an annual evaluation campaign that provides the infrastructure for large-scale testing of search technology. Its purpose is to encourage more powerful, faster and easier-to-use technologies for retrieving information and to transfer the technologies to industry quickly. TREC 2008 has five tracks including one on blogs that includes tasks such as detecting blog posts that express positive or negative opinions on a subject. The legal track focuses on search technology to help the legal profession find digital information pertinent to a case in digital document collections; this year’s focus is electronic discovery that includes word, email and voice “documents.” For each track, NIST provides a test set of documents and search queries. Participants run their own text-retrieval systems on the data and return a list of the top-ranked retrieved documents to NIST. NIST pools the individual results and judges the retrieved documents to determine whether or not they match the criteria 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 June 12, 2008.

John Lehman, Chris Cromer and Xiaoyu Li of the National Institute of Standards and Technology (NIST) have received a 2008 Award for Excellence in Technology Transfer from the Federal Laboratory Consortium (FLC). The award honors employees who have accomplished outstanding work in the process of transferring a technology developed by a federal laboratory. The nominations are judged by representatives from industry, state and local government, academia and federal laboratories.

Over a number of years, NIST staff developed optical power detectors that offer high accuracy for calibration of silicon detectors, fiber-optic power meters and laser power meters. The technology previously was transferred to several branches of the military and other national metrology institutes. The FLC awarded a certificate for excellence in technology transfer to Don Dooley, president of Spectrum Detector Inc. of Lake Oswego, Ore., which recently commercialized products based on the NIST technology.

In the awards brochure, the FLC noted that transfer of this technology is “enabling innovation in such diverse areas as optical communications, laser machining and medicine … This invention has successfully decreased metrological uncertainty for commercial manufacturers and users of energy meters and National Metrology Institutes worldwide and through this technology transfer is improving manufacturing operations and product quality across multiple industries.”

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Editor: Michael Baum

Date created: May 28, 2008
Date updated: May 29, 2008
Contact: inquiries@nist.gov