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Tech Beat - June 10, 2008

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Editor: Michael Baum
Date created: May 4, 2011
Date Modified: May 4, 2011 
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NIST Chemists Get Scoop on Crude 'Oil' from Pig Manure

After a close examination of crude oil made from pig manure, chemists at the National Institute of Standards and Technology (NIST) are certain about a number of things.

Most obviously, “This stuff smells worse than manure,” says NIST chemist Tom Bruno.

But a job’s a job, so the NIST team has developed the first detailed chemical analysis revealing what processing is needed to transform pig manure crude oil into fuel for vehicles or heating. Mass production of this type of biofuel could help consume a waste product overflowing at U.S. farms, and possibly enable cutbacks in the nation’s petroleum use and imports. But, according to a new NIST paper,* pig manure crude will require a lot of refining.

The ersatz oil used in the NIST analyses was provided by engineer Yuanhui Zhang of the University of Illinois Urbana-Champaign. Zhang developed a system using heat and pressure to transform organic compounds such as manure into oil.

As described in the new paper, Bruno and colleagues determined that the pig manure crude contains at least 83 major compounds, including many components that would need to be removed, such as about 15 percent water by volume, sulfur that otherwise could end up as pollution in vehicle exhaust, and lots of char waste containing heavy metals, including iron, zinc, silver, cobalt, chromium, lanthanum, scandium, tungsten and minute amounts of gold and hafnium. Whatever the pigs eat, from dirt to nutritional supplements, ends up in the oil.

While the thick black liquid may look like its petroleum-based counterparts, the NIST study shows that looks can be deceiving. “The fact that pig manure crude oil contains a lot of water is unfavorable. They would need to get the water out,” Bruno says.

The measurements were made with a new NIST test method and apparatus, the advanced distillation curve, which provides highly detailed and accurate data on the makeup and performance of complex fluids. A distillation curve charts the percentage of the total mixture that evaporates as a sample is slowly heated. Because the different components of a complex mixture typically have different boiling points, a distillation curve gives a good measure of the relative amount of each component in the mixture. NIST chemists enhanced the traditional technique by improving precision and control of temperature measurements and adding the capability to analyze the chemical composition of each boiling fraction using a variety of advanced methods.

NIST researchers analyzed the graphite-like char remaining after the distillation by bombarding it with neutrons, a non-destructive way of identifying the types and amounts of elements present. Two complementary neutron methods detected the heavy metals listed above.

Bruno and colleagues currently spend much of their time analyzing military jet fuels and are not planning a major foray into pig manure. But Bruno concedes that the effort may have a payoff. “Who knows, it might help decrease the nuisance of manure piles.”

For more on the process of making pig waste crude, see “Converting Manure to Oil: U of I Lays Groundwork for One-of-a-Kind Pilot Plant”.

* L.S. Ott, B.L. Smith and T.J. Bruno. Advanced distillation curve measurement: Application to a bio-derived crude oil prepared from swine manure. Fuel (2008), doi:10.1016/j.fuel.2008.04.038.

Media Contact: Laura Ost, laura.ost@nist.gov, 303-497-4880

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Microwave Synthesis Connects With the (Quantum) Dots

Materials researchers at the National Institute of Standards and Technology (NIST) have developed a simplified, low-cost process for producing high-quality, water-soluble "quantum dots" for biological research. By using a laboratory microwave reactor to promote the synthesis of the widely used nanomaterials, the recently published* NIST process avoids a problematic step in the conventional approach to making quantum dots, resulting in brighter, more stable dots.

photo of glowing vials

Brightly glowing vials of highly luminescent, water soluble quantum dots produced by the new NIST microwave process span a wavelength range from 500 to 600 nm.

Credit: NIST
View hi-resolution image

Quantum dots are specially engineered nanoscale crystals of semiconductor compounds. The name comes from the fact that their infinitesimal size enables a quantum electronics effect that causes the crystals to fluoresce brilliantly at specific, sharply defined colors. Bright, stable, tiny and tunable across a broad spectrum of colors, quantum dots that are engineered to attach themselves to particular proteins have become a popular research tool in areas such as cancer research for detecting, labeling and tracking specific biomarkers and cells.

Making good quantum dots for biological research is complex. First a semiconductor compound—typically a mixture of cadmium and selenium—must be induced to crystallize into discrete nanocrystals of just the right size. Cadmium is toxic, and the compound also can oxidize easily (ruining the effect), so the nanocrystals must be encapsulated in a protective shell such as zinc sulfide. To make them water soluble for biological applications, a short organic molecule called a “ligand” is attached to the zinc atoms. The organic ligand also serves as a tether to attach additional functional molecules that cause the dot to bind to specific proteins.

The accepted commercial method uses a high-temperature reaction (about 300 degrees Celsius) that must be carefully controlled under an inert gas atmosphere for the crystallization and encapsulation stages. An intermediate ligand material that can tolerate the high temperature is used to promote the crystallization process, but it must be chemically swapped afterwards for a different compound that makes the material water soluble. The ligand exchange step—as well as several variations on the process—is known to significantly alter the luminescence and stability of the resulting quantum dots.

Seeking a better method, NIST researchers turned to microwave-assisted chemistry. Microwaves have been employed in a variety of chemical reactions to reduce the required times and temperatures. Working at temperatures half those of commercial processes, the group developed a relatively simple two-stage process that requires no special atmospheric conditions and directly incorporates the water-soluble ligand into the shell without an exchange step. Using commercially available starting materials, they have synthesized highly uniform and efficient quantum dots for a range of frequencies and shown them to be stable in aqueous solutions for longer than four months.

* M.D. Roy, A.A. Herzing, S.H. De Paoli Lacerda and M,L. Becker. Emission-tunable microwave synthesis of highly luminescent water soluble CdSe/ZnS quantum dots. Chemical Communications, 2008, 2106-2108.

Media Contact: Michael Baum, michael.baum@nist.gov, 301-975-2763

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‘Nanoglassblowing’ Seen as Boon to Study of Individual Molecules

While the results may not rival the artistry of glassblowers in Europe and Latin America, researchers at the National Institute of Standards and Technology (NIST) and Cornell University have found beauty in a new fabrication technique called “nanoglassblowing” that creates nanoscale (billionth of a meter) fluidic devices used to isolate and study single molecules in solution—including individual DNA strands. The novel method is described in a forthcoming paper in the journal Nanotechnology.*

schematic and photograph

Left: Schematic of a T-junction nanofluidic device with a "nanoglassblown" funnel-shaped entrance to a nanochannel. The funnel tapers down to 150 micrometers (about the diameter of a human hair) at the nanochannel entrance.
Right: Photomicrograph of the T-junction with the first section of the nanochannel visible at the bottom. The colors are a white light interference pattern caused by the changing depth of the curved glass funnel.

Credit: Elizabeth Strychalski, Cornell University
View hi-resolution image

Traditionally, glass micro- and nanofluidic devices are fabricated by etching tiny channels into a glass wafer with the same lithographic procedures used to manufacture circuit patterns on semiconductor computer chips. The planar (flat-edged) rectangular canals are topped with a glass cover that is annealed (heated until it bonds permanently) into place. About a year ago, the authors of the Nanotechnology paper observed that in some cases, the heat of the annealing furnace caused air trapped in the channel to expand the glass cover into a curved shape, much like glassblowers use heated air to add roundness to their work. The researchers looked for ways to exploit this phenomenon and learned that they could easily control the amount of “blowing out” that occurred over several orders of magnitude.

As a result, the researchers were able to create devices with “funnels” many micrometers wide and about a micrometer deep that tapered down to nanochannels with depths as shallow as 7 nanometers—approximately 1,000 times smaller in diameter than a red blood cell. The nanoglassblown chambers soon showed distinct advantages over their planar predecessors.

“In the past, for example, it was difficult to get single strands of DNA into a nanofluidic device for study because DNA in solution balls up and tends to bounce off the sharp edges of planar channels with depths smaller than the ball,” says Cornell’s Elizabeth Strychalski. “The gradually dwindling size of the funnel-shaped entrance to our channel stretches the DNA out as it flows in with less resistance, making it easier to assess the properties of the DNA,” adds NIST’s Samuel Stavis.

Future nanoglassblown devices, the researchers say, could be fabricated to help sort DNA strands of different sizes or as part of a device to identify the base-pair components of single strands. Other potential applications of the technique include the manufacture of optofluidic elements—lenses or waveguides that could change how light is moved around a microchip—and rounded chambers in which single cells could be confined and held for culturing.

This work was supported in part by Cornell’s Nanobiotechnology Center, part of the National Science Foundation’s Science and Technology Center Program. It was performed while Samuel Stavis held a National Research Council Research Associateship Award at NIST.

* E.A. Strychalski, S.M. Stavis and H.G. Craighead. Non-planar nanofluidic devices for single molecule analysis fabricated using nanoglassblowing. Nanotechnology, To be osted online the week of June 15, 2008.

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

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Tests Check Out Rescue Robots' Life-Saving Vision

To save lives, search and rescue robots crawling through the rubble of a collapsed building or surveying a chemical spill area must be capable of beaming back clear, easily interpretable images of what they “see” to operators and emergency planners, working away from the immediate disaster site. A new ASTM International standard, developed under a National Institute of Standards and Technology (NIST) coordinated program with first responders and manufacturers, offers a systematic way to evaluate the robot visual capability humans need to drive the device, search for victims and access general hazard conditions. Emergency personnel will be able to use the test data to select the best systems for their specific needs. Industry adoption of the standard is expected to accelerate innovation, development and deployment of the life-saving robots.

In science fiction, images relayed from robots are readily interpretable by remote operators. Reality can be different. Real-time color video images from urban search-and-rescue robots reflect the type of sensors or camera lens used. A zoom lens, for instance, can be like looking through a soda straw, yet it could be useful in zeroing in on certain important objects. Similarly, images from a lens offering a wide field of view, such as 120 to 150 degrees, offer little depth perception and are of little use for navigating in tight quarters but can, in the case of aerial robots and ground vehicles, provide useful survey data. Both far-vision acuity and near vision acuity, in such instances, can be important for surveys of HAZMAT disaster sites, with the far-vision cameras providing the overall picture and the near-vision acuity playing a critical role in reading chemical labels. (Near-vision acuity also is critical for small robots that must operate in confined spaces.) Finally, the amount of available light can affect monitor images.

The standard’s test methods measure the field of view of the camera, the system’s visual acuity at far distances with both ambient lighting and lighting onboard the robot, visual acuity at near distances, again in both light and dark environments, and visual acuity in both light and dark environments with zoom lens capability, if provided. Results are useful for writing procurement specifications and for acceptance testing of robots for urban search and rescue applications.

Further information on NIST’s urban search and rescue robot performance standards project, which is sponsored by the U.S. Department of Homeland Security Science and Technology Directorate, can be found at www.isd.mel.nist.gov/US&R_Robot_Standards . Additional information on the new standard ASTM E2566-08, “Standard Tests Methods for Determining Visual Acuity and Field of View on-board Video Systems for Teleoperation of Robots for Urban Search and Rescue Applications,” can be found at www.astm.org/Standards/E2566.htm.

Media Contact: John Blair, inquiries@nist.gov, 301-975-4261

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NIST’s Novel ‘Noise Thermometry’ May Help Redefine International Unit of Temperature

After seven years of work, researchers at the National Institute of Standards and Technology (NIST) have built a system that relies on the “noise” of jiggling electrons as a basis for measuring temperatures with extreme precision. The system is nearly precise enough now to help update some of the crucial underpinnings of science, including the 54-year-old definition of the Kelvin, the international unit of temperature.

photo of circuit

Photograph of circuit used in NIST’s Johnson noise thermometry system. The system relies on the “noise” of jiggling electrons as a basis for measuring temperatures. It is extremely precise in part because it is based on the predictable quantum effects of superconducting elements located between the dashed slits on the top and bottom of the chip.

Credit: NIST
View higher-resolution image

NIST’s Johnson noise thermometry (JNT) system, described Monday, June 9, at the Conference on Precision Electromagnetic Measurements,* represents a fivefold advance in the state-of-the-art in noise thermometry thanks to its use of a unique quantum voltage source combined with recent reductions in systematic errors and uncertainty. It is also simpler and more compact than other leading systems for measuring high temperatures, such as those based on the pressure and volume of gases.

“What’s beautiful about our JNT system is that it’s so conceptually simple,” says project leader Sam Benz. “All the measurements are electrical—they don’t require large volumes of gas and mechanical systems that change in different environmental conditions.”

As a thermometer, the JNT system will be most useful in the range from approximately 500 K (227 degrees C or 440 degrees F) to 1235 K (962 degrees C or 1763 degrees F). Its most obvious application is as a primary measurement standard (maintained at NIST and other national metrology labs for calibration of thermometers), but it also might be used directly in some industrial thermometry labs.

The recent JNT improvements are especially significant because they may contribute to a separate important measurement problem, the determination of Boltzmann’s constant. Several years from now, the international metrology community is expected to fix the value of the Boltzmann constant, used in scientific calculations to relate energy to temperature in particles. The Boltzmann constant, in turn, would then be used to redefine the Kelvin as part of an international effort to link all units to fundamental constants, a more stable and reproducible approach than traditional measurement standards based on physical objects or substances. The current Kelvin is defined in terms of the triple-point temperature of water (273.16 K, or about 0 degrees C and 32 degrees F), or the temperature and pressure at which water’s solid, liquid and vapor forms coexist in balance.

The JNT system is the only electrical approach to determining the Boltzmann constant and is currently among the top three thermometry systems competing for the redefinition, in terms of offering the lowest uncertainties, Benz says.

The NIST system measures very small electrical noise in resistors, a common electronic component, when they are cooled to the water triple point. This “Johnson noise” is caused by the random motion of electrons and is directly proportional to temperature. The unique aspect of the system is the use of precision waveforms—electrical signals—synthesized with a superconducting alternating current (AC) voltage source whose output is based on fundamental principles of quantum mechanics to calibrate the electronic devices measuring the noise power. This enables the system to match electrical power and thermal-noise power at the triple point of water. NIST was able to include this capability in the JNT system thanks to its recent development of the first precision instrument for synthesizing fundamentally accurate AC voltages. The quantum nature of the design assures that copies of the system will produce identical results in different laboratories, a feature that is impossible with artifact-based standards.

The most accurate measurement of the Boltzmann constant to date was performed at NIST about two decades ago using acoustic gas thermometry. The JNT system would require further improvements to be competitive with the acoustic method, but Benz thinks this is possible. A downside to the JNT system is its slow speed: It will take about one month to integrate the data to achieve the precision needed to define the Boltzmann constant, Benz says.

* S.P. Benz, H. Rogalla, D.R. White, Jifeng Qu, P.D. Dresselhaus, W.L. Tew and S.W. Nam. 2008. Improvements in the NIST Johnson Noise Thermometry System. Presented at the Conference on Precision Electromagnetic Measurements, Broomfield, Colo., June 9.

Media Contact: Laura Ost, laura.ost@nist.gov, 303-497-4880

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Research Measures Movement of Nanomaterials in Simple Model Food Chain

New research* shows that while engineered nanomaterials can be transferred up the lowest levels of the food chain from single-cell organisms to higher multicelled ones, the amount transferred was relatively low and there was no evidence of the nanomaterials concentrating in the higher level organisms. The preliminary results observed by researchers from the National Institute of Standards and Technology (NIST) suggest that the particular nanomaterials studied may not accumulate in invertebrate food chains.

Photomicrograph of ciliate T. pyriformis
photomicrograph of rotifer B. calyciflorus

Photomicrograph of ciliate T. pyriformis (l.) during cell division with accumulated quantum dots appearing red and closeup photomicrograph of rotifer B. calyciflorus (r., whole organism seen in upper left corner) with quantum dots assimilated from ingested ciliates appearing red.

Credit: NIST
View hi-resolution image of image on leftView hi-resolution image of image on right

The same properties that make engineered nanoparticles attractive for numerous applications—biological and environmental stability, small size, solubility in aqueous solutions and lack of toxicity to whole organisms—also raise concerns about their long-term impact on the environment. NIST researchers wanted to determine if nanoparticles could be passed up a model food chain and if so, did the transfer lead to a significant amount of bioaccumulation (the increase in concentration of a substance in an organism over time) and biomagnification (the progressive buildup of a substance in a predator organism after ingesting contaminated prey).

In their study, the NIST team investigated the dietary accumulation, elimination and toxicity of two types of fluorescent quantum dots using a simple, laboratory-based food chain with two microscopic aquatic organisms—Tetrahymena pyriformis, a single-celled ciliate protozoan, and the rotifer Brachionus calyciflorus that preys on it. The process of a material crossing different levels of a food chain from prey to predator is called “trophic transfer.”

Quantum dots are nanoparticles engineered to fluoresce strongly at specific wavelengths. They are being studied for a variety of uses including easily detectable tags for medical diagnostics and therapies. Their fluorescence was used to detect the presence of quantum dots in the two microorganisms.

The researchers found that both types of quantum dots were taken in readily by T. pyriformis and that they maintained their fluorescence even after the quantum dot-containing ciliates were ingested by the higher trophic level rotifers. This observation helped establish that the quantum dots were transferred across the food chain as intact nanoparticles and that dietary intake is one way that transfer can occur. The researchers noted that, “Some care should be taken, however, when extrapolating our laboratory-derived results to the natural environment.”

“Our findings showed that although trophic transfer of quantum dots did take place in this simple food chain, they did not accumulate in the higher of the two organisms,” says lead author David Holbrook. “While this suggests that quantum dots may not pose a significant risk of accumulating in aquatic invertebrate food chains in nature, additional research beyond simple laboratory experiments and a more exact means of quantifying transferred nanoparticles in environmental systems are needed to be certain.”

* R.D. Holbrook, K.E. Murphy, J.B. Morrow and K.D. Cole. Trophic transfer of nanoparticles in a simplified invertebrate food chain. Nature Nanotechnology, June 2008 (advance online publication).

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

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Eighty-Five Take First Step Toward 2008 Baldrige Award

Eighty-five organizations—the highest number of applicants since 1992—are in the running for the 2008 Malcolm Baldrige National Quality Award, the nation’s highest recognition for excellence. Applicants include three manufacturers, five service companies, seven small businesses, 11 educational organizations, 43 health care organizations and 16 nonprofits/governmental organizations.

The 85 applicants will be evaluated rigorously by an independent board of examiners in seven areas: leadership; strategic planning; customer and market focus; measurement, analysis, and knowledge management; workforce focus; process management; and results. Examiners provide each applicant with 300 to 1,000 hours of review and a detailed report on the organization’s strengths and opportunities for improvement.

The 2008 Baldrige Award recipients are expected to be announced in late November.

Named after Malcolm Baldrige, the 26th Secretary of Commerce, the Baldrige Award was established by Congress in 1987. The award—managed by the National Institute of Standards and Technology (NIST) in collaboration with the private sector—promotes excellence in organizational performance, recognizes the achievements and results of U.S. organizations, and publicizes successful performance strategies. The award is not given for specific products or services. Since 1988, 72 organizations have received Baldrige Awards.

The Baldrige Criteria for Performance Excellence have played a valuable role in helping U.S. organizations improve. The Criteria are designed to help organizations improve their performance by focusing on three goals: delivering ever-improving value to customers and stakeholders, improving the organization’s overall effectiveness, and organizational and personal learning. Several million copies of the Criteria have been distributed since 1988, and wide-scale reproduction by organizations and electronic access add to that number significantly.

For more information on the Baldrige award program, see http://baldrige.nist.gov.

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

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NIST Advisory Group Welcomes Three New Members

James M. Turner, deputy director of the National Institute of Standards and Technology (NIST), has named three distinguished experts from industry and academia to serve on the Visiting Committee on Advanced Technology (VCAT), the agency’s primary private-sector policy advisory group. The new VCAT members—who will serve three-year terms—bring the body’s number to 10.

New member Peter Green, president in 2006 of the Materials Research Society, is Vincent T. and Gloria M. Gorguze Professor of Engineering and Department Chair at the University of Michigan, where he also holds a professorship in chemical engineering, macromolecular science and engineering.

Pradeep Khosla, whose previous positions include program manager at Defense Advanced Research Projects Agency, is currently the dean of the Carnegie Mellon’s College of Engineering, as well as the Philip and Marsha Dowd University Professor in the College of Engineering and School of Computer Science.

Alan Taub is the executive director in charge of GM Research & Development and oversees GM’s seven science laboratories around the world. He also has responsibility for GM’s advanced technical work activity and runs GM’s global technology collaboration network.

The VCAT was established by Congress in 1988 to review and make recommendations on NIST’s policies, organization, budget and programs and most recently amended by the 2007 America COMPETES Act. The VCAT chair is James W. Serum, president of SciTek Ventures, and the vice chair is Vinton G. Cerf, vice president and chief Internet evangelist for Google.

For a list of all members and more information, please see the NIST VCAT Web site (www.nist.gov/director/vcat/).

Media Contact: Michael Baum, baum@nist.gov, 301-975-2763

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Everything You Want To Know About SI (But Were Afraid to Ask)

Relax, even scientists can sometimes use help when making conversions and measurements with the modern metric system, the International System of Units (known as SI from the French “Le Systeme International d’Unites”.) The good news is that the National Institute of Standards and Technology (NIST) has just released a guide for researchers, available to all, on correct SI usage and unit conversion.

NIST Special Publication (SP) 811, Guide for the Use of the International System of Units, complements the recently released U.S. version of the English language SI Brochure, SP 330, the eighth version of international standard reference guide to the modern metric system. (See “NIST Offers U.S. Interpretations of Recent SI (Metric) Changes”.)

SP 811 offers an extensive conversion factor appendix useful for measurement unit conversions and appropriate rounding strategies for data. It also provides an editorial checklist for reviewing manuscripts’ conformity with the SI and the basic principles of physical quantities and units. A color chart has been added that illustrates the utilization of the SI base units in defining the 22 derived units with special names and symbols.

NIST SP 811 and NIST SP 330 are available online at http://physics.nist.gov/cuu/Units and at http://nist.gov/metric. Printed copies can be requested with an email to TheSI@nist.gov.

Media Contact: Michael Baum, michael.baum@nist.gov, 301-975-2763

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