NIST Tech Beat - Aug. 31, 2006

Researchers have figured out how nanoscale microwave transmitters gain greater signal power than the sum of their parts—a finding that will help in the design of nano-oscillator arrays for possible use as transmitters and receivers in cell phones, radar systems, or computer chips.

Groups of nanoscale magnetic oscillators are known to synchronize their individual 10-nanowatt signals to achieve a signal strength equal to the square of the number of devices. Now scientists at the National Institute of Standards and Technology (NIST), Seagate Research Center (Pittsburgh, Pa.) and Hitachi Global Storage Technologies (San Jose, Calif.) have discovered how—the oscillators accomplish this feat by communicating by means of “spin waves,” their magnetic emissions caused by oscillating patterns in the spin of electrons.

The discovery, reported in the Aug. 25 issue of Physical Review Letters, provides a tool for designing “spintronic” devices, which are based on the spin of electrons instead of their charge as in conventional electronics. The NIST oscillators—nanoscale electrical contacts applied to sandwiches of two magnetic films separated by a non-magnetic layer of copper—are hundreds of times smaller than typical commercial microwave generators and potentially could replace much bulkier and expensive components.

The NIST team previously reported “locking” the signals of two oscillators www.nist.gov/public_affairs/releases/nanooscillators.htm but were not sure why this occurred. They suspected spin waves, which propagate through solid magnetic materials, or magnetic fields, which propagate through air or a vacuum. So they did an experiment by making two oscillators on the same slab of magnetic multilayer, locking their signals, and then cutting a gap in the solid material between the two devices. The locking stopped.

Lead author Matthew Pufall of NIST compares spin wave locking to dropping two rocks in different sides of a pool of water, so that ripples propagate outward from each spot until they meet and merge. Each oscillator shifts the frequency of its own spin waves to match that of the incoming wave; this “frequency pulling” gets stronger as the frequencies get closer together, until they lock. Each oscillator also adjusts the peaks and troughs of its wave pattern to the incoming wave, until the two sets of waves synchronize.

*M.R. Pufall, W.H. Rippard, S.E. Russek, S. Kaka, J.A. Katine. 2006. Electrical measurement of spin-wave interactions of proximate spin transfer nano-oscillators. Physical Review Letters. Aug. 25.

Gold nanoparticles are highly efficient and sensitive “handles” for biological molecules being manipulated and tracked by lasers, but they also can heat up fast—by tens of degrees in just a few nanoseconds—which could either damage the molecules or help study them, according to scientists at JILA, a joint institute of the National Institute of Standards and Technology (NIST) and University of Colorado at Boulder.

Biophysicists often study nanoscale and even picoscale mechanics by using lasers to both apply force to and track the position of fragile biomolecules such as DNA or protein by manipulating a tiny sphere—typically polystyrene—attached to the molecule. The JILA team would like to find new microsphere materials that can be trapped by laser radiation pressure more efficiently, which would enable faster measurements and detection of smaller motions at the same laser power. As described in the Aug. 15 issue of Optics Letters,* the JILA team demonstrated that 100-nanometer-wide gold beads, as expected because of their metallic nature, can be trapped and detected six times more easily than polystyrene particles of a similar size.

However, the scientists also found that gold absorbs light and heats up quickly, by a remarkable 266 degrees (Celsius) per watt of laser power, at the wavelength most often used in optical traps. Unless very low laser power is used, the heat could damage the molecules under study. Thus, gold beads would not be useful for temperature-sensitive experiments or applying force to molecules. But the heating effect could be useful in raising local temperatures in certain experiments, such as heating a protein just enough to allow scientists to watch it unfold, the paper suggests.

The work was supported by a W.M. Keck grant in the RNA Sciences, a Burroughs Wellcome Fund Career Award in the Biomedical Sciences, a National Institutes of Health training grant, the National Science Foundation, and NIST.

* Y. Seol, A.E. Carpenter, T.T. Perkins. 2006. Gold nanoparticles: enhanced optical trapping and sensitivity coupled with significant heating. Optics Letters. Aug. 15.

The 1995 bombing that triggered the collapse of the Alfred P. Murrah Federal Building in Oklahoma City, Okla., first raised concerns in the United States about the safety of public buildings from “progressive collapse” (the spread of an initial local failure in a structure until it results in the collapse of the entire building or a disproportionately large part of it). Since that event and the subsequent terrorist attacks of Sept. 11, 2001, both private and public groups have begun to address progressive collapse as a design requirement for new buildings.

Working with experts in the design, construction and operation of buildings, the National Institute of Standards and Technology (NIST) has prepared a comprehensive set of best practices guidelines for reducing the likelihood of progressive collapse of structures, and is participating in a series of technical workshops to spread the word.

Development, publication and dissemination of the report, Best Practices for Reducing the Potential for Progressive Collapse in Buildings, responds to one of the 30 recommendations for improvements to building codes, standards and practices in the final report of NIST's investigation into the WTC disaster. Among the items featured in the document are: an acceptable risk approach to progressive collapse, a review of design methods used to enhance a building's resistance to progressive collapse, a look at progressive collapse provisions in building standards around the world, and case studies of progressive collapse events triggered by abnormal loading (where building integrity is compromised by unexpected hazards from explosions, aircraft or vehicle impacts, foundation failures, construction errors, etc.).

To aid the understanding and use of the guidelines, and to provide an opportunity for technical exchange with the lead authors of the report, NIST and the Structural Engineering Institute (SEI) of the American Society of Civil Engineers (ASCE) has organized a series of four workshops across the nation. The workshop dates and locations are: Sept. 7, Denver; Sept. 14, New York City; Sept. 28, San Francisco; and Oct. 19, Chicago (as part of the 2006 ASCE Annual Conference).

All pre-registered attendees will receive a draft copy of the NIST document in advance of the workshop. To register online, select a date and location under "Progressive Collapse Workshops" at the SEI Web site, www.seinstitute.org.

Before ditching or donating that used computer, CD or other data-storage media, sensitive or personal information should be properly “sanitized,” according to a new guide from the National Institute of Standards and Technology (NIST). Information systems store information using a wide variety of media, including “hard” copy, such as paper printouts and facsimile ribbons, and electronic media, including cell phones, CDs or DVDs, and hard drives. Even if stored data supposedly has been deleted, in many cases residual data can be retrieved and reconstructed.

The NIST guide, Guidelines for Media Sanitization (NIST Special Publication 800-88), provides information on techniques to remove data from a wide variety of media types and a decision matrix to determine which technique is best. The guide recommends that organizations first determine the confidentiality of the information and then decide how to dispose of the media.

The guide also recommends that organizations establish an information security governance structure, and describes the security responsibilities of everyone in the organization—from program managers and agency heads to users.

The National Institute of Standards and Technology (NIST) has co-organized with U.S. industry a workshop to address the increasing pressure on manufacturers from emerging chemical controls and regulations from such countries as China and the European Union. The suite of issues stemming from regulatory actions in various markets, as well as global reporting and management efforts, has serious cost and market implications both for manufacturers of chemicals and for chemicals users and are potential barriers to innovation.

The workshop, “Innovation and Competitiveness: A Strategic Approach to Emerging Chemical Issues,” will be held on Sept. 26-27 at the NIST laboratories in Gaithersburg, Md.

The costs of dealing with multiple chemical regulation and control requirements in different markets goes far beyond the chemical industry itself. Chemicals and chemical products contribute 16 percent of the value of material inputs in the automotive sector, 33 percent of the value of material inputs used to make semiconductors, and 30 percent of the value of medical supplies, for example. The European Union’s "End-of-Life-Vehicles" (ELV) Directive affected thousands of U.S. automotive suppliers. A study conducted by the Original Equipment Suppliers Association (OESA) found that the average cost for inputting data into the International Material Data System (IMDS), a tool for complying with the ELV requirements, was $75 per simple raw material and up to $2,500 per complex assembly. In 2002, an Automotive Industry Action Group (AIAG) project team used these data and estimated that total costs to the entire U.S. supply chain for ELV compliance would be in the hundreds of millions of dollars.

The workshop will provide a forum to gather industry views on these issues and to develop an early consensus on how the business, scientific and technical communities can better address and prepare for new chemical-related rules and regulations world-wide that affect U.S. manufacturing.

For more information and/or to register for the workshop, go to the NIST Web site: www.nist.gov/public_affairs/confpage/060926.htm.

Americans are living longer than ever. As the senior population grows over the coming years, increasing the quality of healthcare while reducing costs will become even more of a priority than it is today. New home-based healthcare technologies and electronic health information will help seniors take charge of their own healthcare, maintain their independence, and reduce costs. While government and private industry are working together to make healthcare more affordable and more accessible, one barrier is the interoperability of medical devices and equipment as well as electronic health information. The Department of Commerce’s Technology Administration and National Institute of Standards and Technology and the Center for Aging Services Technologies are hosting a summit Oct. 18-19, 2006, in Gaithersburg, Md., to identify issues and challenges needed to make interoperable healthcare technology and health information a reality. Speakers include Michael O. Leavitt, secretary, U.S. Department of Health and Human Services and Craig R. Barrett, chairman of the board, Intel Corporation. For more information, see www.itl.nist.gov/Healthcare%20Summit/intro.htm.

When the National Institute of Standards and Technology (NIST) released the final report in October 2005 from its technical investigation of the fires and collapses of the World Trade Center (WTC) towers on Sept. 11, 2001, many in the building design, construction, fire, rescue, safety and legislative communities praised the three-year effort as the authoritative accounting of the events that took place and began working with NIST to use the report's 30 recommendations to improve building codes, standards and practices. However, there have been claims from "alternative theory" groups that factors other than those described in the NIST report brought the towers down.

To respond to a number of the questions raised, NIST has posted a fact sheet on the investigation Web site (http://wtc.nist.gov). The fact sheet explains how NIST found no corroborating evidence for alternative hypotheses suggesting that the WTC towers were brought down by controlled demolition using explosives planted prior to 9/11, or that missiles were fired at or hit the towers. Instead, the fact sheet describes how photographs and videos from several angles clearly showed that the collapse initiated at the fire and impact floors and that the collapse progressed from the initiating floors downward, until the dust clouds obscured the view.

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Editor: Michael Baum

Date created: 8/31/06
Date updated: 8/31/06
Contact: inquiries@nist.gov