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Lab News -- November 23, 2007

November 23, 2007

LabNews 11/23/2007PDF (450 kb)

Buckyball birth observed by Sandia CINT researcher Jianyu Huang

By Neal Singer

Almost everyone in the scientific community has heard of buckyballs, but no one until Sandia’s Jianyu Huang (1132) had seen one being born.

A paper detailing the work was published in the Oct. 26 Physical Review Letters and immediately highlighted in Nature Nanotechnology, New Scientist, and EETimes.

Buckyballs — more formally known as buckminsterfullerene C60 — are carbon-linked nanostructures named for their resemblance to the geodesic dome macrostructures favored for their strength by environmentalist Buckminster Fuller.

In addition to the strength generated by their carbon-carbon bonds — “the strongest chemical bonds in Mother Nature,” says Jianyu, who still seems awed by the properties of the nanomaterial — the structure forms a relatively impermeable cage that conceivably could safely transport molecules of hydrogen for fuel, or tiny doses of medicine to targeted sites within the human body.

But before their widespread use is possible, buckyballs have to be available in large numbers. To achieve that, a better understanding of how they form is crucial.

“We have now the first direct, in situ, experimental proof of the hypothesis — very significant to the scientific community — that these structures are formed by the heated ‘shrink-wrapping’ of carbon sheets,” says Jianyu.

That is, heating bends single-atomic-layer carbon sheets into nano bowls, and then adds more carbon atoms to the edge of the bowls until the formation of giant fullerenes — larger, less stable versions of the C60 molecule. Continued application of heat reduces these fullerenes — “shrink-wrapping” is the favored term — to the size of stable C60 molecules, the buckyball: the smallest stable arrangement of carbon atoms in that shape.

In further heating, the buckyball vanishes, further proof that the buckyball stage had been reached.

Buckyball codiscoverer (1985) and Nobel laureate (1996) Richard Smalley had hypothesized that buckyballs are formed in this fashion, but at the time of his death in 2005 no experimental confirmation was yet available and other methods have been proposed.

Jianyu’s discovery happened unexpectedly. He was looking for flaws in nanotube durability. Transmitting electric current through the atom-sized tip of a scanning tunneling microscope (STM) inside a transmission electron microscope (TEM), he had heated a 10-nano-meter-diameter multiwalled carbon nanotube to approximately 2,000 degrees Celsius when he saw the exterior shells of giant fullerenes form from peelings within the nanotube. High-resolution 2-D images of the process taken by a CCD camera attached to the microscope showed the fullerenes reducing in diameter, linearly with time, until the structure became the size of C60, the smallest arrangement of carbon atoms that form the soccer ball shape.

Then the buckyballs vanished.

Simulations created at Jianyu’s request by professor Boris Yakobson’s team at Rice University, who coauthored the Physical Review paper, show that heating could reduce fullerenes by emitting carbon dimers (pairs of atoms) until they reached the basic buckyball shape. Further removal of carbon pairs collapsed the structure.

Buckyballs are formed by hexagonal and pentagonal arrangements of carbon atoms that seem stitched or welded together, in appearance much like a soccer ball. Their curvature, however, is caused by the pentagons alone, 12 to a buckyball. Departing atoms leave the same number of pentagons until the fullerene shrinks below its smallest stable shape, below which the buckyball disintegrates.

“I used to study metals,” says Jianyu, who grew up in a remote Chinese farming village and now utilizes the most complex instruments at Sandia’s Center for Integrated Nanotechnologies. “But carbon nanomaterials now are much more interesting to me.”

CINT is a joint effort of Sandia and Los Alamos national labs and is supported by the DOE’s Office of Science.

The buckyball discovery was initially made by Jianyu on similar instruments at Boston College, and then interpreted at CINT.

“The STM probe inside the TEM is a very powerful tool in nanotechnology,” Jianyu says.

“The STM probe is like God’s finger: It can grab extremely small objects, as small as a single atomic chain, enabling me to do nanomechanics, nanoelectronics, and even thermal studies of carbon nanotubes and nanowires.”

The research was paid for by CINT and Laboratory Directed Research and Development. -- Neal Singer

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Yucca Mountain uses Sandia cognitive software to verify records management complianceSandia's Combustion Research Facility

By Chris Burroughs

Among the tasks required to license Yucca Mountain as a storage facility for spent nuclear fuel and high-level radioactive waste is for DOE to certify that it has made available to the Nuclear Regulatory Commission

(NRC) — the licensing agency — all necessary “documentary material,” including emails, reports, and other correspondence.

But how do you weed through the thousands of documents and email records associated with the Yucca Mountain Project to determine which are relevant to licensure?

Yucca Mountain personnel found the solution in algorithms developed by Sandia’s Cognitive Science and Technology Program.

They turned to a text analysis system built for the program that can quickly differentiate relevant documents from nonrelevant ones or to determine relationships between documents. Specifically, they are using two software systems that perform different functions and generate different types of data — Licensing Support Network Archive Assistant (LSNAA) and Data Trace Tool. Both are part of STACY, a suite of tools used for document analysis.

LSNAA is helping validate the way text-based materials, like emails, are identified as relevant — i.e., pertinent to the licensing process. All of the documents are originally categorized by members of the workforce using guidance provided by DOE. LSNAA provides an automated means of validating that individuals are applying the guidance consistently and correctly.

“A good [human] reviewer can look at 500 emails a day,” says Justin Basilico (6341), who led design and development of the algorithms used in the STACY LSNAA. “That means to review 10,000 emails a day requires 20-person days. LSNAA saves time and money by reducing the effort as much as 90 percent.”

The LSNAA software analyzes messages that have been categorized by subject-matter experts and learns how to differentiate relevant from nonrelevant email messages. When applied to a database of emails, for example, LSNAA shows the user what messages appear to have incorrectly implemented the guidance, making it faster to find potential inconsistencies in categorization. The tool provides a search capability that allows users to search for specific information by key word, date, and categorization.

Justin says the cognitive software makes the second of three reviews categorizing the emails. Human originators make the first categorization, and human reviewers always make the final decision as to which emails are truly relevant.

The other Sandia software tool used at Yucca Mountain to prepare the license defense is the Data Trace Tool.

Data Trace watches analysts while they trace from high-level analysis model reports down to raw data collected in lab notebooks, representing that work as a graph with “nodes.” This provides a means to qualify and support the validity of the model reports that can be saved and accessed again later.

“Previously everything had to be done by hand,” says Zach Benz (6341), Data Trace Tool lead developer. “We provided a new tool that delivers a visual representation of the user’s tracing history.”

The tool is in use by the analysts now.

Wendy Shaneyfelt (6341), member of the cognition team and project manager for development of the two tools, says she is pleased that tools developed as part of Sandia’s augmented cognition research benefited the Yucca Mountain project.

“This represents tech transfer in its best sense from our cognitive research to a real-world application,” she says. -- Chris Burroughs

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Sandia named a ‘fit business’ by California Wellness Task Force

By Patti Koning

Sandia/California has met the gold standard, at least according to the California Fit Business Award. Earlier this month, the site’s Preventive Health and Life Design Center (LDC) received the highest level of recognition in the program, which seeks and recognizes business models that promote a healthier workplace.

In a letter to site health promotion coordinator and educator Morgan Edwinson (8527), state Sen. Tom Torlakson, D-Dist. 7, wrote that “your company is being recognized as a leader in California for the steps you have taken to ensure employee health.”

The Fit Business Award focuses on four main areas: “Eat Better,” “Move More,” “Promote Healthy Lifestyles,” and “Create a Culture.”

Morgan says providing better nutrition on the site has been a recent focus in response to negative feedback about the lack of healthy food choices. The LDC team partnered with Health, Benefits, and Employee Services to set about improving choices at the on-site grab-and-go deli, vending machines, and catering. The goal is to stock vending machines with at least 50 percent healthy, balanced choices. A further step is to increase the price of less healthy options.

Large posters at the on-site deli provide complete nutrition information for some of the popular items sold and advice on how to make meals healthier. Site dietitian Deja Chornenky (8527) is working with approved caterers to create healthier menus. She is also working to have preferred caterers make at least 50 percent of their menus offerings healthy. Recently best practice standards for healthy food choices have been incorporated in the request for proposal process for food vendors.

Deja leads a Healthy Eating, Healthy Heart class designed to help participants lose weight through healthy eating, exercise, and healthy lifestyle habits. The LDC offers plenty of opportunities for employees to move more. Exercise classes include tai chi, yoga, circuit training, and outdoor, mentor-led walking groups. Health risk assessments are a key part of the program.

Emily Thompson (8527), the LDC fitness specialist, organizes a variety of fitness programs and services for the site. Among those services are fitness challenges offered throughout the year. The “Maintain No Gain” program is currently under way, which challenges participants not to gain any weight during the holiday season. (For more information contact Emily at 925-294-3703.)

Nearly 2,000 health risk assessments have been conducted to date. In the five years that the LDC has been open, there have been 730 active participants. About 70 people use the LDC each work day.

Site management received high marks for the broad acceptance and support of healthy lifestyle and preventative health programming. The Managers’ Peak Performance Program was created to engage and encourage managers to shift perspectives and begin creating balance in their work and personal lives. Managers participate for six months, during which they identify a personal breakthrough that they would like to create in the work-life balance.

Engineering Services Manager Howard Royer (8207) credits the Managers’ Peak Performance Program with helping him achieve his goal of cholesterol reduction. “The program helped me emphasize diet, stress reduction, and work/life balance, wherein I got my cholesterol down to a healthy level by the end of the program,” says Howard. “I encourage my staff to take advantage of the LDC and Health Benefits programs because I feel strongly that healthy people are the best contributors to Sandia and the community.”

Tim Shepodd, manager of Materials Chemistry Dept. 8778, was looking for peace when he participated in Managers’ Peak Performance. “This happened at a time when there was a lot of change and resulting stress,” he recalls. “My goal was to be at peace and set an example for my staff.”

He found value in being able to examine his management style and performance in a nonthreatening environment. “Ordinarily, there’s not a real venue to do that,” says Tim. “The hardest thing to do is set aside the time, but when I can, it is spectacularly valuable.”

While Morgan is pleased with the Fit Business Award, she’s not resting on her laurels. “We want to continue following up on health risk assessments and improving nutrition on site,” she says. “We’ve seen good results from our followups, but we’ll have a better picture in a couple of years. The next step is to link illness, attendance, and productivity with participation in LDC programs.” -- Patti Koning

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