In This Issue...
NIST Corrosion Lab Tests Suggest Need for Underground Gas Tank Retrofits
A hidden hazard may lurk*** beneath many of the roughly 156,000 gas stations across the United States.
The hazard is corrosion in parts of underground gas storage tanks—corrosion that could result in failures, leaks and contamination of groundwater, a source of drinking water. In recent years, field inspectors in nine states have reported many rapidly corroding gas storage tank components such as sump pumps. These incidents are generally associated with use of gasoline-ethanol blends and the presence of bacteria, Acetobacter aceti, which convert ethanol to acetic acid, a component of vinegar.
Following up on the inspectors’ findings, a National Institute of Standards and Technology (NIST) laboratory study* has demonstrated severe corrosion—rapidly eating through 1 millimeter of wall thickness per year—on steel alloy samples exposed to ethanol and acetic acid vapors. Based on this finding, NIST researchers suggest gas stations may need to replace submersible pump casings, typically made of steel or cast iron, sooner than expected. Such retrofits could cost an estimated $1,500 to $2,500 each, and there are more than 500,000 underground gas storage tanks around the country.
The NIST study focused only on sump pump components, located directly below access covers at filling stations, just above and connected to underground gas storage tanks. The sump pumps move fuel from underground tanks to the fuel dispensers that pump gas into cars. These underground tanks and pipes also may be made of steel and could be vulnerable, too. “We know there are corrosion issues associated with the inside of some tanks. We’re not sure, at this point, if that type of corrosion is caused by the bacteria,” NIST co-author Jeffrey Sowards says.
Much of the U.S. fuel infrastructure was designed for unblended gasoline. Ethanol, an alcohol that can be made from corn, is now widely used as a gasoline additive due to its oxygen content and octane rating, or antiknock index. A previous NIST study found that ethanol-loving bacteria accelerated pipeline cracking.**
For the latest study, NIST researchers developed new test methods and equipment to study copper and steel alloy samples either immersed in ethanol-water solutions inoculated with bacteria, or exposed to the vapors above the medium—conditions mimicking those around sump pumps. Corrosion rates were measured over about 30 days.
The NIST study confirmed damage similar to that seen on sump pumps by field inspectors. The worst damage, with flaky iron oxide products covering corrosion, was found on steel exposed to the vapors. Copper in both the liquid and vapor environments also sustained damage, but corrosion rates were slower. Steel corroded very slowly while immersed in the liquid mixture; the NIST paper suggests bacteria may have created a biofilm that was protective in this case.
Although copper corroded slowly—it would take about 15 years for 1.2-millimeter-thick copper tube walls to develop holes—localized corrosion was observed on cold-worked copper, the material used in sump pump tubing, NIST co-author Elisabeth Mansfield notes. Therefore, stress-corrosion cracking is a concern for bent copper tubing because it would greatly reduce tube lifetime and result in leaks.
The NIST test equipment developed for the study could be used in future investigations of special coatings and biocides or other ways to prevent sump pump failures and leaks.
NIST held a workshop in July 2013 on biocorrosion associated with alternative fuels. Presentations and information from this workshop can be found at www.nist.gov/mml/acmd/biocorrosion.cfm.
*J.W. Sowards and E. Mansfield. Corrosion of copper and steel alloys in a simulated underground storage tank sump environment containing acid producing bacteria. Corrosion Science. July, 2014. In press, corrected proof available online. DOI: 10.1016/j.corsci.2014.07.009.
**See 2011 NIST Tech Beat article, “NIST Finds That Ethanol-Loving Bacteria Accelerate Cracking of Pipeline Steels,” at www.nist.gov/mml/acmd/201108_ethanol_pipelines.cfm.
Media Contact: Laura Ost, firstname.lastname@example.org, 303-497-4880
Readying Your Community to Deal with Disaster
This week, experts are meeting at the New Jersey Institute of Technology in Hoboken to discuss how communities can prepare themselves to minimize the impacts of major disasters like Hurricane Sandy, the 2012 “superstorm,” and quickly restore vital functions and services. The workshop is the second of three sponsored by the National Institute of Standards and Technology (NIST).
In a post on The Commerce Blog, Stephen Cauffman, NIST’s lead researcher for disaster resilience, writes, “Although communities cannot dodge hazardous events … they can take concrete actions in advance to minimize the toll that natural—and even human-caused—hazards inflict and to speed up the pace of recovery. Communities can make themselves more resilient to disasters.”
“Providing tools and guidance to help U.S. communities become more disaster resilient is the goal of a collaborative, nationwide effort led by NIST. Carried out under the President's Climate Action Plan, this recently launched national initiative will yield a comprehensive disaster resilience framework that will help communities develop plans to protect people and property before disaster strikes, and to recover more rapidly and efficiently.”
Media Contact: Mark Bello, email@example.com, 301-975-3776
Latest NIST Mass Spectral Library: Expanded Coverage, Features
The world’s most widely used and trusted resource for identifying mass spectra, the “fingerprints” of molecules, has undergone a major expansion, according to its managers at the National Institute of Standards and Technology (NIST). NIST 14, containing the newest edition of the NIST/EPA/NIH Mass Spectral Library, boasts significantly increased coverage within each of its three components: the NIST/EPA/NIH Mass Spectral Library of electron ionization (EI) spectra, the NIST Tandem Mass Spectral Library, and the NIST Library of GC Methods and Retention Index Data. These updated libraries were recently released to more than 30 distributors worldwide.
Mass spectrometry (MS) is routinely used to quickly and accurately identify chemical compounds for a wide range of applications such as drug detection, pollution monitoring, petrochemical processing and disease diagnosis via biomarkers. To use the method, a target molecule is first converted to an ionized gas. Fragmenting these ions into their components produces other ions whose intensities (abundances), when sorted according to mass and charge, produce a pattern known as a “mass spectrum.” This spectrum serves as a fingerprint for identifying the target molecule. To ensure an accurate ID, the spectrum should be compared with a verified reference spectrum from a database such as the NIST/EPA/NIH Mass Spectral Library.
NIST 14 is made up of three databases and accompanying search software. The tool provides researchers with:
Each spectrum in the new library has been critically examined by experienced mass spectrometrists at NIST and collaborating organizations, and each chemical structure has been scrutinized for correctness and consistency.
“This release provides one of the most significant enhancements in the long history of the Mass Spectral Library, with major increases in coverage for both the EI and tandem collections along with a higher level of organization of the data within them,” says Stephen Stein, director of the NIST Mass Spectrometry Data Center and one of the researchers responsible for the development of NIST 14.
Among the other improvements to NIST 14 are a greatly expanded variety of precursor ions for tandem mass spectra; integration of retention index and mass spectral data; a new way to display the structures of molecular derivatives and the reagents that yield them; new search methods for high mass accuracy data; and the use of the International Chemical Identifier (InChI) standard for representing chemical structures (developed by NIST and the International Union of Pure and Applied Chemistry), which makes it easier to find additional information about molecular IDs made by the Mass Spectral Library.
For more information and a list of vendors offering NIST 14, go to www.nist.gov/srd/nist1a.cfm.
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Enhanced NIST Instrument Enables High-speed Chemical Imaging of Tissues
A research team from the National Institute of Standards and Technology (NIST), working with the Cleveland Clinic, has demonstrated a dramatically improved technique for analyzing biological cells and tissues based on characteristic molecular vibration "signatures." The new NIST technique is an advanced form of the widely used spontaneous Raman spectroscopy, but one that delivers signals that are 10,000 times stronger than obtained from spontaneous Raman scattering, and 100 times stronger than obtained from comparable "coherent Raman" instruments, and uses a much larger portion of the vibrational spectrum of interest to cell biologists.*
The technique, a version of "broadband, coherent anti-Stokes Raman scattering" (BCARS), is fast and accurate enough to enable researchers to create high-resolution images of biological specimens, containing detailed spatial information on the specific biomolecules present at speeds fast enough to observe changes and movement in living cells, according to the NIST team.
Raman spectroscopy is based on a subtle interplay between light and molecules. Molecules have characteristic vibration frequencies associated with their atoms flexing and stretching the molecular bonds that hold them together. Under the right conditions, a photon interacting with the molecule will absorb some of this energy from a particular vibration and emerge with its frequency shifted by that frequency—this is "anti-Stokes scattering." Recording enough of these energy-enhanced photons reveals a characteristic spectrum unique to the molecule. This is great for biology because in principle it can identify and distinguish between many complex biomolecules without destroying them and, unlike many other techniques, does not alter the specimen with stains or fluorescent or radioactive tags.
Using this intrinsic spectral information to map specific kinds of biomolecules in an image is potentially very powerful, but the signal levels are very faint, so researchers have worked for years to develop enhanced methods for gathering these spectra.** "Coherent" Raman methods use specially tuned lasers to both excite the molecular vibrations and provide a bright source of probe photons to read the vibrations. This has partially solved the problem, but the coherent Raman methods developed to date have had limited ability to access most of the available spectroscopic information.
Most current coherent Raman methods obtain useful signal only in a spectral region containing approximately five peaks with information about carbon-hydrogen and oxygen-hydrogen bonds. The improved method described by the NIST team not only accesses this spectral region, but also obtains excellent signal from the "fingerprint" spectral region, which has approximately 50 peaks—most of the useful molecular ID information.
The NIST instrument is able to obtain enhanced signal largely by using excitation light efficiently. Conventional coherent Raman instruments must tune two separate laser frequencies to excite and read different Raman vibration modes in the sample. The NIST instrument uses ultrashort laser pulses to simultaneously excite all vibrational modes of interest. This "intrapulse" excitation is extremely efficient and produces its strongest signals in the fingerprint region. "Too much light will destroy cells," explains NIST chemist Marcus Cicerone, "So we've engineered a very efficient way of generating our signal with limited amounts of light. We've been more efficient, but also more efficient where it counts, in the fingerprint region."
Raman hyperspectral images are built up by obtaining spectra, one spatial pixel at a time. The hundred-fold improvement in signal strength for the NIST BCARS instrument makes it possible to collect individual spectral data much faster and at much higher quality than before—a few milliseconds per pixel for a high-quality spectrum versus tens of milliseconds for a marginal quality spectrum with other coherent Raman spectroscopies, or even seconds for a spectrum from more conventional spontaneous Raman instruments. Because it's capable of registering many more spectral peaks in the fingerprint region, each pixel carries a wealth of data about the biomolecules present. This translates to high-resolution imaging within a minute or so whereas, notes NIST electrical engineer Charles Camp, Jr., "It's not uncommon to take 36 hours to get a low-resolution image in spontaneous Raman spectroscopy."
"There are a number of firsts in this paper for Raman spectroscopy," Camp adds. "Among other things we show detailed images of collagen and elastin—not normally identified with coherent Raman techniques—and multiple peaks attributed to different bonds and states of nucleotides that show the presence of DNA or RNA."
*C.H. Camp Jr., Y.J. Lee, J.M. Heddleston, C.M. Hartshorn, A.R. Hight Walker, J.N. Rich, J.D. Lathia and M.T. Cicerone. High-speed coherent Raman fingerprint imaging of biological tissues. Nature Photonics, Published online July 20, 2014. doi:10.1038/nphoton.2014.145.
**See for example the 2010 Tech Beat story, "Faster CARS, Less Damage: NIST Chemical Microscopy Shows Potential for Cell Diagnostics" at www.nist.gov/public_affairs/tech-beat/tb20101013.cfm#cars.
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'Comb on a Chip' Powers New NIST/Caltech Atomic Clock Design
Researchers from the National Institute of Standards and Technology (NIST) and California Institute of Technology (Caltech) have demonstrated a new design for an atomic clock that is based on a chip-scale frequency comb, or a microcomb.
The microcomb clock, featured on the cover of the inaugural issue of the new journal Optica,* is the first demonstration of all-optical control of the microcomb, and its accurate conversion of optical frequencies to lower microwave frequencies. (Optical frequencies are too high to count; microwave frequencies can be counted with electronics.)
The new clock architecture might eventually be used to make portable tools for calibrating frequencies of advanced telecommunications systems or providing microwave signals to boost stability and resolution in radar, navigation and scientific instruments. The technology also has potential to combine good timekeeping precision with very small size. The comb clock might be a component of future "NIST on a chip" technologies offering multiple measurement methods and standards in a portable form.
"The microcomb clock is one way we might get precision frequency metrology tools out of the lab and into real-world settings," NIST physicist Scott Diddams says.
Frequency combs produce precisely defined colors, or frequencies, of light that are evenly spaced throughout the comb's range. (The name comes from the spectrum's resemblance to the teeth of a pocket comb.) The original combs required relatively large lasers that produced rapid, extremely short pulses of light, but more recently NIST and other laboratories have developed much smaller microcombs.**
A microcomb generates its set of frequencies from light that gets trapped in the periphery of a tiny silica glass disk, looping around and around the perimeter. These combs can be astonishingly stable. NIST has an ongoing collaboration in this area with Caltech researchers, who made the 2-millimeter-wide silica disk that generates the frequency comb for the new clock.
The new microcomb clock uses a laser to excite the Caltech disk to generate a frequency comb, broadens the spectrum using nonlinear fiber, and stabilizes two comb teeth (individual frequencies) to energy transitions in rubidium atoms that "tick" at optical frequencies. (Conventional rubidium atomic clocks operate at much lower microwave frequencies.) The comb converts these optical frequency ticks to the microwave domain.
Thanks to the gear-like properties of the disk and the comb, the output is also 100 times more stable than the intrinsic ticking of the rubidium atoms. According to Diddams, "A simple analogy is that of a mechanical clock: The rubidium atoms provide stable oscillations—a pendulum—and the microcomb is like a set of gears that synthesizes optical and microwave frequencies."
The center of the comb spectrum is locked to an infrared laser operating at 1560 nanometers, a wavelength used in telecommunications.
NIST researchers have not yet systematically analyzed the microcomb clock's precision. The prototype uses a tabletop-sized rubidium reference. The scientists expect to reduce the instrument size by switching to a miniature container of atoms like that used in NIST's original chip-scale atomic clock.*** Scientists also hope to find a more stable atomic reference.
The microcomb chip was made by use of conventional semiconductor fabrication techniques and, therefore, could be mass produced and integrated with other chip-scale components such as lasers and atomic references. NIST researchers expect that, with further research, the microcomb clock architecture can achieve substantially better performance in the future.
The research is supported in part by the Defense Advanced Research Projects Agency and National Aeronautics and Space Administration.
*S.B. Papp, K. Beha, P. Del'haye, F. Quinlan, H. Lee, K.J. Vahala and S.A. Diddams. A microresonator frequency comb optical clock. Optica 1, 10-14. July 22, 2014.
**See 2011 NIST Tech Beat article, "Future 'Comb on a Chip': NIST's Compact Frequency Comb Could Go Places," at www.nist.gov/pml/div688/comb-102511.cfm.
***See 2013 NIST Tech Beat article, "NIST Scientists Win 2014 Rank Prizes for Chip-Scale Atomic Clock," at www.nist.gov/pml/div688/rank-052813.cfm, and additional links in the footnotes.
Media Contact: Laura Ost, firstname.lastname@example.org, 303-497-4880
NIST Shows Ultrasonically Propelled Nanorods Spin Dizzyingly Fast
Vibrate a solution of rod-shaped metal nanoparticles in water with ultrasound and they'll spin around their long axes like tiny drill bits. Why? No one yet knows exactly. But researchers at the National Institute of Standards and Technology (NIST) have clocked their speed—and it's fast. At up to 150,000 revolutions per minute, these nanomotors rotate 10 times faster than any nanoscale object submerged in liquid ever reported.
The discovery of this dizzying rate has opened up the possibility that they could be used not only for moving around inside the body—the impetus for the research—but also for high-speed machining and mixing.
Scientists have been studying how to make nanomotors move around in liquids for the past several years. A group at Penn State looking for a biologically friendly way to propel nanomotors first observed that metal nanorods were moving and rotating in response to ultrasound in 2012. Another group at the University of California San Diego then directed the metal rods' forward motion using a magnetic field. The Penn State group then demonstrated that these nanomotors could be propelled inside of a cancer cell.
But no one knew why or how fast the nanomotors were spinning. The latter being a measurement problem, researchers at NIST worked with the Penn State group to solve it.
"If nanomotors are to be used in a biological environment, then it is important to understand how they interact with the liquid and objects around them," says NIST project leader Samuel Stavis. "We used nanoparticles to trace the flow of water around the nanomotors, and we used that measurement to infer their rate of rotation. We found that the nanomotors were spinning surprisingly rapidly."
The NIST team clocked the nanomotors' rotation by mixing the 2-micrometer-long, 300-nanometer-wide gold rods with 400-nanometer-diameter polystyrene beads in water and putting them between glass and silicon plates with a speaker-type shaker beneath. They then vibrated the shaker at an ultrasonic tone of 3 megahertz—much too high for you or your dog to hear—and watched the motors and beads move.
As the motors rotate in water, they create a vortex around them. Beads that get close get swept up by the vortex and swirl around the rods. By measuring how far the beads are from the rods and how fast they move, the group was able to work out how quickly the motors were spinning—with an important caveat.
"The size of the nanorods is important in our measurements" says NIST physicist Andrew Balk. "We found that even small variations in the rod's dimensions cause large measurement uncertainties, so they need to be fabricated as uniformly as possible for future studies and applications."
According to the researchers, the speed of the nanomotors' rotation seems to be independent of their forward motion. Being able to control the "speed and feed" of the nanomotors independently would open up the possibility that they could be used as rotary tools for machining and mixing.
Future avenues of research include trying to discover exactly why the motors rotate and how the vortex around the rods affects their interactions with each other.
*A.L. Balk, L.O. Mair, P.P. Mathai, P.N. Patrone, W.Wang, S. Ahmed, T.E. Mallouk, J.A. Liddle and S.M. Stavis. Kilohertz rotation of nanorods propelled by ultrasound, traced by microvortex advection of nanoparticles. ACS Nano, Articles ASAP (As Soon As Publishable) Publication Date (Web): July 14, 2014. DOI: 10.1021/nn502753x.
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Fill ‘er Up: NIST Develops Prototype Meter Test for Hydrogen Refueling Stations
To support the fair sale of gaseous hydrogen as a vehicle fuel, researchers at the National Institute of Standards and Technology (NIST) have developed a prototype field test standard to test the accuracy of hydrogen fuel dispensers.* Once the standard is field tested, it will serve as a model for constructing similar devices for state weights and measures inspectors to use.
Three automakers plan to begin selling hydrogen-fueled vehicles to consumers in 2015. The state of California has opened nine refueling stations and is funding the construction of an additional 28 hydrogen stations during the next few years to service the growing number of hydrogen fuel cell vehicles on their roads.
NIST Handbook 44, the bedrock reference text for weights and measures inspectors, includes specifications, tolerances and other requirements for commercial weighing and measuring equipment ranging from gasoline dispensers to grocery store scales. Handbook 44, which has been adopted by all states, stipulates that hydrogen will be sold by the kilogram, and according to Juana Williams, a NIST weights and measures expert, hydrogen-dispensing pumps must be accurate to within 2 percent, or 20 grams, per kilogram.
"It's much more difficult to measure hydrogen gas delivered at 5,000 to 10,000 psi than it is to measure a product that is a liquid at atmospheric temperatures and pressures," says Williams. "While a kilogram of hydrogen has approximately the same energy content as a gallon of gasoline, the allowable error is slightly less stringent than for gasoline."
Even with the larger allowance, some have suggested these tolerances are too tight and proposed alternatives as high as 10 or 20 percent. What isn't clear is whether these claims arise because the meters are unable to perform within the tolerance specified in Handbook 44 or if the equipment and methods used to conduct testing are contributing larger errors to the process. Regardless, consumers expect to receive the product they pay for and businesses expect to receive fair payment for the product they sell.
"We've shown that the master meter in our lab is capable of dispensing helium from a simulated hydrogen dispenser with errors of 1 percent or less," says NIST's Jodie Pope, who designed the field testing apparatus. "So we can extrapolate that it is possible to measure hydrogen with accuracy sufficient for a fair marketplace."
The next challenge is to determine what accuracy is achievable in field installations of hydrogen dispensing systems when using NIST traceable standards and well-defined test equipment and test procedures and to then translate this into guidance for use by weights and measures inspectors and industry.
*J. Pope and J. Wright. Performance of Coriolis Meters in Transient Gas Flows. Flow Measurement and Instrumentation. March 17, 2014.
Media Contact: Mark Esser, firstname.lastname@example.org, 301-975-8735
NIST, HHS Sponsor 7th Annual Conference on Healthcare Information Security
The seventh annual “Safeguarding Health Information: Building Assurance through HIPAA Security” conference will be held September 23-24, 2014, in Washington, D.C. The meeting is co-hosted by the National Institute of Standards and Technology (NIST) and the Department of Health and Human Services’ Office for Civil Rights (OCR).
The conference will explore the current health information technology security landscape in the context of the Health Insurance Portability and Accountability Act (HIPAA) Security Rule. The Security Rule sets federal requirements for protecting the confidentiality, integrity and availability of electronic protected health information by requiring HIPAA covered entities and their business associates to implement and maintain administrative, physical and technical safeguards.
This event will highlight the present state of health information security and practical strategies, tips and techniques for implementing the HIPAA Security Rule.
Conference sessions will explore security management and technical assurance of electronic health information. Presentations will cover topics that include updates on the Omnibus HIPAA/HITECH Final Rule, breach management, strengthening cybersecurity in the health care sector, integrating security safeguards into health IT, managing risk and securing mobile devices.
NIST provides ongoing expertise in risk management, security and standards for federal agencies and has been involved in health information technology research since 1994. NIST is responsible for accelerating the development and harmonization of standards and developing conformance test tools for health information technology.
OCR enforces the HIPAA Privacy Rule, which protects the privacy of individually identifiable health information; the HIPAA Security Rule; the confidentiality provisions of the Patient Safety Rule, which protect identifiable information being used to analyze patient safety events and improve patient safety; and the breach notification regulations requiring HIPAA-covered entities and their business associates to notify individuals when their health information is accessed without authorization.
For those who cannot attend in person, the conference is being webcast. Registration instructions, current agenda and conference logistics are available at www.nist.gov/itl/csd/safeguarding-health-information-building-assurance-through-hipaa-security-2014.cfm. All registrations include access to archived webcast presentations and materials.
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