NIST Tech Beat - July 22, 2008

Adding just the right dash of nanoparticles to standard mixes of lubricants and refrigerants could yield the equivalent of an energy-saving chill pill for factories, hospitals, ships, and others with large cooling systems, suggest the latest results from National Institute of Standards and Technology (NIST) research that is pursuing promising formulations.

NIST experiments with varying concentrations of nanoparticle additives indicate a major opportunity to improve the energy efficiency of large industrial, commercial, and institutional cooling systems known as chillers. These systems account for about 13 percent of the power consumed by the nation’s buildings, and about 9 percent of the overall demand for electric power, according to the Department of Energy.

NIST researcher Mark Kedzierski has found that dispersing “sufficient” amounts of copper oxide particles (30 nanometers in diameter) in a common polyester lubricant and combining it with an equally pedestrian refrigerant (R134a) improves heat transfer by between 50 percent and 275 percent. “We were astounded,” he says.

Results of this work have been presented at recent conferences and will be reported in an upcoming issue of the ASME Journal of Heat Transfer.

Just how nanomaterial additives to lubricants improve the dynamics of heat transfer in refrigerant/lubricant mixtures is not thoroughly understood. The NIST research effort aims to fill gaps in knowledge that impede efforts to determine and, ultimately, predict optimal combinations of the three types of substances.

“As with all good things, the process is far from foolproof,” Kedzierski explains. “In fact, an insufficient amount or the wrong type of particles might lead to degradation in performance.”

On the basis of work so far, the researcher speculates several factors likely account for nanoparticle-enabled improvements in heat-transfer performance. For one, nanoparticles of materials with high thermal conductivity improve heat transfer rates for the system. Preliminary results of the NIST research also indicate that, in sufficient concentrations, nanomaterials enhance heat transfer by encouraging more vigorous boiling of the mixture. The tiny particles stimulate, in effect, double bubbles—secondary bubbles that form atop bubbles initiated at the boiling site. Bubbles carry heat away from the surface, and the fact that they’re being formed more efficiently because of the nanoparticles means the heat gets transferred more readily.

Other interactions, Kedzierski says, also are likely to contribute to the dramatic performance improvements reported at NIST and elsewhere.

Success in optimizing recipes of refrigerants, lubricants and nanoparticle additives would pay immediate and long-term dividends. If they did not harm other aspects of equipment performance, high-performance mixtures could be swapped into existing chillers, resulting in immediate energy savings. And, because of improved energy efficiency, next-generation equipment would be smaller, requiring fewer raw materials in their manufacture.

Researchers at the National Institute of Standards and Technology (NIST) and three collaborating institutions are using a new laboratory model of the membrane surrounding neurons in the brain to study how a protein long suspected of a role in early-stage Alzheimer’s disease actually impairs a neuron’s structure and function. The team’s findings are reported in a new paper in the Biophysical Journal.*

The brain’s neurons transmit nerve impulses down a long stem that is surrounded by a two-layer membrane. In the neuron’s normal, “rest” state, this membrane actively sorts sodium ions to the outside of the cell and potassium ions to the inside. To transmit a nerve impulse, an electrochemical change ripples down the membrane in advance of the impulse, making it temporarily more permeable and allowing the ions to swap places. That in turn changes the electrical potential across the membrane, allowing the impulse to pass. Afterwards, the membrane returns to rest and begins sorting the ions again.

Medical experts have hypothesized for years that small polypeptides called amyloid beta peptides somehow create a “leaky” membrane that disrupts this balanced back-and-forth switching of the electrical potential and, in turn, normal impulse transmission. Alzheimer’s disease—the progressive brain disorder that is the nation’s sixth leading cause of death—is believed to start with such breakdowns. As the disease progresses, amyloid beta peptides clump together to form plaques that further destroy nerve function.

Studying the beginnings of Alzheimer’s is nearly impossible in humans because by the time the disease is diagnosed, most patients have moved into its later stages. Researchers at NIST have developed a laboratory model that recreates a simplified version of the nerve cell membrane, allowing the study of Alzheimer’s disease mechanisms at the molecular level. A clever piece of molecular-level design, the system is built by first covering a silica surface with gold. Sulfur atoms, which bond well to gold, are then added to act as anchors to hold the bilayer membrane. The result is a stable, tethered membrane with an aqueous environment on both sides that accurately models the behavior of the nerve cell membrane.

A collaborative team of researchers from NIST, Carnegie Mellon University, the University of California-Irvine and the Biochemistry Institute (BCHI) in Vilnius, Lithuania, exposed the membrane model to different concentrations of a specific form of amyloid beta peptides comprised of soluble, tiny (5-6 nanometers, approximately twice the diameter of a DNA helix) chains. The researchers found increased cation movement across the normally strong barrier at the higher concentrations of the peptides. The data support the hypothesis that membrane “leakiness” is not due to a permanent hole being formed but rather to an aggregation of amyloid beta peptides in the membrane that allows cations to be passed from peptide to peptide across the bilayer, like a baton handed off by relay runners.

The researchers are continuing to use their model system to better understand the role amyloid beta peptides play in early-stage Alzheimer’s disease. Future plans include investigating how amyloid beta peptide aggregates arrange themselves in the membrane, how the peptide aggregates affect or influence calcium channels (portals for calcium ion movement) in the membrane, and how the peptides interact with membranes constructed with other types of lipids.

* G. Valincius, F. Heinrich, R. Budvytyte, D.J. Vanderah, D.J. McGillvray, Y. Sokolov, J.E. Hall and M. Losche. Soluble amyloid ß oligomers affect dielectric membrane properties by bilayer insertion and domain formation: Implications for cell toxicity. Biophysical Journal (published online June 13, 2008).

Titanium, a protean element with applications from pigments to aerospace alloys, could get a new role as an environmentally friendly additive for automotive oil, thanks to work by materials scientists from Afton Chemical Corporation (Richmond, Va.) and the National Institute of Standards and Technology (NIST). In a recent paper,* the researchers established that a titanium compound added to engine oil creates a wear-resistant nanoscale layer bound to the surface of vulnerable engine parts, making it a credible substitute for older compounds that do not coexist well with antipollution equipment.

Modern engine lubricating oil is a complex, highly engineered mixture, up to 20 percent of which may be special additives to enhance properties such as viscosity and stability and to reduce sludge formation and engine wear, according to Afton specialists. For years antiwear additives for high-performance oils have been phosphorous compounds, particularly ZDDP,** that work by forming a polyphosphate film on engine parts that reduces wear. Unfortunately phosphorus is a chemical poison for automobile catalytic converters, reducing their effectiveness and life span, so industry chemists have been searching for ways to replace or reduce the use of ZDDP. It’s not a simple problem because the additive has several useful functions in addition to wear resistance.

Titanium is one candidate replacement. Mechanical tests of an organic titanium compound at Afton demonstrated that it provided superior wear resistance when added to a fully formulated engine oil, suggesting that oil chemists could use less ZDDP. Just how the titanium compound works was an open question, however. Surface analysis tests could detect titanium in the wear tracks of test surfaces but not with enough sensitivity to determine its chemical nature—and whether, for example, it was just lying there or bound to the metal surface. To resolve the issue, the researchers turned to NIST’s soft X-ray beamline at the National Synchrotron Light Source (NSLS) in Brookhaven, N.Y.

The NIST beamline instruments use low-energy (“soft”) X-rays that can be precisely tuned to specific elements to measure chemical bonds both at the surface of a sample and deeper into the bulk of the material. Powered by the NSLS, the facility is at least 10 times more sensitive than commonly available instruments. The measurements revealed that the antiwear enhancement comes from titanium chemically bound into the metal structure of the engine surface, forming a hard oxide, iron titanate. Comparing the test data to that of several possible compounds, the research team was able to identify the specific oxide. While considerably more work remains to be done, the results suggest that titanium could play an important role in future low-phosphorus lubricating oils.

* J.M. Guevremont, G.H. Guinther, D. Szemenyei, M.T. Devlin, T.-C. Jao, C. Jaye, J. Woicik and D.A. Fischer. Enhancement of engine oil wear and friction control performance through titanium additive chemistry. Tribology Transactions, Volume 51, 324-331, 2008.

Scientists at the National Institute of Standards and Technology (NIST) have developed a technique to measure the formation of clumps of proteins in protein-based pharmaceuticals. This first systematic study* clarifies the conditions under which scientists can be assured that their instruments are faithfully measuring the formation of protein aggregates, a major concern because of its impact on quality control and safety in biologic drug manufacturing.

Proteins, a main constituent of many new drugs, are large molecules that have a tendency to stick to each other and form clumps during their manufacture. These clumps have been associated with severe immune responses. In at least one case, the inadvertent creation of protein clumps during the processing of a drug to treat anemia caused an immune reaction in about 250 patients that destroyed their ability to produce red blood cells. Those patients now have to receive blood transfusions every few days to replenish these vital cells.

Events such as this led the Food and Drug Administration to call for the development of sensitive and rapid measurement tools that can detect aggregation of protein drugs during the manufacturing phase. To address the problem, NIST researchers hit upon the idea of adapting a technique known as electrospray differential mobility analysis (ES-DMA). Commonly used to size soot and other aerosols, ES-DMA uses an electric current to vaporize a solution of proteins into tiny charged water droplets, each containing a single protein molecule or protein aggregate. Once these droplets evaporate, the charged proteins and protein aggregates are drawn into an oppositely charged tube. By making controlled adjustments to the voltage of the tube and the velocity of the air flowing through it, researchers can collect particles of a specific size, allowing the proteins and protein aggregates to be precisely sorted and counted.

The NIST team adapted the technique for biopharmaceutical applications. According to researcher Leonard Pease, ES-DMA is tricky to get right, but the NIST team was able to define the conditions needed to electrospray proteins and protein aggregates reliably and repeatedly. NIST scientists favor ES-DMA for its ability to quickly resolve particle sizes differing by as little as 0.2 nanometers, to provide a direct measure of particle size distributions, and to accept bioreactor samples with significantly reduced preparation requirements.

In addition to sizing proteins, Pease said the technique could also be used to accurately size many different types of particles used in medicine, such as the viruses used in the human papillomavirus (HPV) vaccine and gene therapy. “The adaptation of this technology is just one of many excellent examples of how NIST seeks out and works with U.S. industry,” says Willie E. May, director of the NIST Chemical Science and Technology Laboratory.

* L. Pease, J. Elliott, D. Tsai, M. Zachariah and M. Tarlov. Determination of protein aggregation with differential mobility analysis: application to IgG antibody. Biotechnology and Bioengineering. Available online at http://dx.doi.org/10.1002/bit.22017.

Data breaches are a recurring nightmare for IT managers responsible for securing not only their company’s confidential data, but possibly also sensitive information belonging to their clients, such as social security numbers or health or financial records. To help managers safeguard valuable information most efficiently, computer scientists at the National Institute of Standards and Technology (NIST) are applying security metrics to computer network pathways to assign a probable risk of attack to guide IT managers in securing their networks.

“We analyze all of the paths that system attackers could penetrate through a network,” says computer scientist Anoop Singhal, “and assign a risk to each component of the system. Decision makers can use our assigned probabilities to make wise decisions and investments to safeguard their network.” The research was presented at a conference earlier this month.*

Computer networks are made up of components varying from individual computers, to servers and routers. Once inside a network’s firewall, for a seemingly mild-mannered purpose as posting an image to a file transfer protocol (FTP) site, a hacker can travel through the network through a variety of routes to hit the jackpot of valuable data. In addition to hardware, the hacker can break in through software on the computers, especially file-sharing applications that have been blamed for some major data breaches recently.

NIST researchers evaluate each route and assign it a risk based on how challenging it is to the hacker. The paths are determined using a technique called “attack graphs.” A new analysis technique based on attack graphs was jointly developed by Singhal and research colleagues at George Mason University. A patent is pending on the technique.

Singhal and his team determine risk by using these attack graphs and NIST’s National Vulnerability Database (NVD). This government repository includes a collection of security-related software weaknesses that hackers can exploit. NVD data was collected from software vendors and scores are assigned from most to least insecure by experts.

For example in a simple system there is an attacker on a computer, a firewall, router, an FTP server and a database server. The goal for the attacker is to find the simplest path into the jackpot—the database server. Attack Graph Analysis determines three potential attack paths. For each path in the graph, the NIST researchers assign an attack probability based on the score in the NVD database.

Because it takes multiple steps to reach the goal, the probabilities of each component are multiplied to determine the overall risk. One path takes only three steps. The first step has an 80 percent chance of being hacked, the second, a 90 percent chance. The final step requires great expertise, so there is only a 10 percent probability it can be breached. By multiplying the three probabilities together, that path is pretty secure with a less than 10 percent chance of being hacked.

The next step is for the researchers to expand their research to handle large-scale enterprise networks.

* L. Wang, T. Islam, T. Long, A. Singhal and S. Jajodia. An Attack Graph Based Probabilistic Security Metric. IFIP WG 11.3 Conference on Data and Application Security, London, United Kingdom.

A new set of eight videos on a single DVD can help organizations large and small learn about the outstanding management practices and successful strategies of the five recipients of the 2007 Malcolm Baldrige National Quality Award.

The DVD showcases PRO-TEC Coating Co. (small business category), Mercy Health System (health care), Sharp HealthCare (health care), City of Coral Springs (nonprofit) and the U.S. Army Armament Research, Development and Engineering Center (nonprofit) in separate videos and together in an overview program. Also included on the DVD are two special shows: “Getting Results! The Baldrige National Quality Program” and “Celebrating Excellence—20th Anniversary of the Malcolm Baldrige National Quality Award.”

The DVD is available from the American Society for Quality, P.O. Box 3066, Milwaukee, WI 53201-3066, (800) 248-1946 for $35.00. Use order number T1520. Other Baldrige National Quality Program materials also are available from the same source.

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.

The National Institute of Standards and Technology (NIST) is requesting nominations of qualified individuals for its eight existing Federal Advisory Committees. Nominations for all committees will be accepted on an ongoing basis and will be considered as and when vacancies arise. A July 15, 2008, Federal Register notice (available at www.nist.gov/tip/nist_advisory_board_frn.pdf) details each committee, including numbers of members sought, objectives and duties for members, and nomination procedures.

New to the list of NIST advisory committees this year is the Technology Innovation Program (TIP) Advisory Board. This body seeks its first 10 members to provide guidance to NIST’s newest program, TIP, that supports, promotes and accelerates innovation in the United States through high-risk, high-reward research in areas of critical national need.

The other NIST advisory committees described in the Federal Register notice are: the Board of Overseers of the Malcolm Baldrige National Quality Award, the Judges Panel of the Malcolm Baldrige National Quality Award, the Information Security and Privacy Advisory Board, the Manufacturing Extension Partnership Advisory Board, the National Construction Safety Team Advisory Board, the Advisory Committee on Earthquake Hazards Reduction, and the Visiting Committee on Advanced Technologies.

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Editor: Michael Baum

Date created: July 22, 2008
Date updated: July 22, 2008
Contact: inquiries@nist.gov