Aug. 3, 2006

	In This Issue:
	New X-Ray Microbeam Answers 20-Year-Old Metals Question
	Links Between DNA Damage and Breast Cancer Studied
	NIST Makes Changes to Key Security Publication
	Quick Links
	Workshop Addresses Imaging Technology in Therapeutics
	Two NIST Researchers Earn Presidential Honors
	ANSI Exec Will Help Iraq with Standards

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New X-Ray Microbeam Answers 20-Year-Old Metals Question

Novel 3-D microbeam experiment enables direct proof of the Mughrabi model of metal stress. Submicron X-ray beam (broad arrow) penetrates a deformed copper single crystal and is diffracted onto a CCD detector. Platinum wire profiler (circle) traverses the sample and successively intercepts diffracted X-rays, providing depth measurement and allowing strains to be measured from individual dislocation cells. Credit: NIST View hi-res image

What happens to metals when you bend them? The question isn’t as easy as you may think. A research team from the National Institute of Standards and Technology (NIST), Oak Ridge National Laboratory (ORNL), and the University of Southern California, using a unique X-ray probe, has gathered the first direct evidence showing that, on average, a 20-year-old model is a useful predictor of stresses and strains in deformed metal.*

But the measurements also show that averages can be deceiving.  They mask extremely large variations in stresses that, until now, had gone on undetected. The experiments have implications for important practical problems in sheet metal forming and control of metal fatigue, which is responsible for many structural materials failures.

 

When metals deform, the neat crystal structure breaks into a complex three-dimensional web of crystal defects called “dislocation walls” that enclose cells of dislocation-free material. The effect is like micron-sized bubbles in foam. These complex dislocation structures are directly responsible for the mechanical properties of virtually all metals, and yet they remain very poorly understood in spite of decades of research. Twenty years ago, the German researcher Häel Mughrabi theorized that the stresses in the dislocation walls and the cell interiors would be different and have opposite signs—an important result for modeling the effects of shaping and working metal on its properties. Until now there has only been indirect evidence for Mughrabi’s model because of the problem of precisely measuring stress at the micron level in individual cells in the dislocation structure.

 

At that level, in fact, stresses can vary greatly. “Scientifically, these stress fluctuations are probably the single most significant finding of the work since no previous measurements even hinted at their existence,” explains NIST physicist and lead author Lyle Levine. “A few researchers had speculated that such variations might exist but they had no clue about their size and distribution.”

The NIST/ORNL/USC team used intense X-ray microbeams—100 times thinner than a human hair—generated at the Advanced Photon Source at Argonne National Laboratory to scan samples of single-crystal copper that had been deliberately stressed. The diffracted X-rays revealed the local crystal lattice spacing, a measure of stress, at each point. As this happens, a thin platinum wire is moved across the face of the crystal. By noting which diffracted rays are blocked by the wire at which point, the team calculated the depth of the region diffracting the beam. They determined cell positions in three dimensions to within half a micron.

The experiments on both compressed and tensioned copper crystals agreed with Mughrabi’s model. “One big advantage to this method is that the results are completely definitive. We can make unambiguous, quantitative measurements from the submicron sample volumes most pertinent to metals deformation,” Levine says.

 

The new technique opens a detailed window into the microstructure of stress in metals and provides quantitative data to support computer models of mechanical stress. The research was supported by NIST and the Department of Energy.

 

*L.E. Levine, B.C. Larson, W. Yang, M.E. Kassner, J.Z. Tischler, M.A. Delos-Reyes, R.J. Fields, and W. Liu. X-ray microbeam measurements of individual dislocation cell elastic strains in deformed single-crystal copper. Nature Materials, 5, 619-622 (2006)

Media Contact:
Mark Bello, mark.bello@nist.gov, (301) 975-3776

 

Links Between DNA Damage and Breast Cancer Studied

Researchers from the Pacific Northwest Research Institute (PNRI) and the National Institute of Standards and Technology (NIST) have uncovered a pattern of DNA damage in connective tissues in the human breast that could shed light on the early stages of breast cancer and possibly serve as an early warning of a heightened risk of cancer.

In the United States, breast cancer is the second leading cause of cancer-related death in women. Breast cancer detection and therapy generally target epithelial cells, the primary locus of breast cancers, but in recent years evidence has accumulated that genetic mutations that develop into cancer may occur initially in a deeper layer of breast tissue, called the stroma. Genetic changes in this connective tissue that supports the breast’s network of glands and ducts have been reported to precede the malignant conversion of tumor cells, but the actual role of stromal cells in the early stages of breast cancer initiation and progression is not well understood.

 

In two recent papers*, the PNRI/NIST team explored the occurrence of damage to stromal DNA caused by free radicals and other oxidants. NIST researchers used a high-precision chemical analysis technique (liquid chromatography/mass spectrometry with isotope dilution) to identify specific DNA lesions, while the PNRI team used a spectroscopic technique (Fourier transform-infrared spectroscopy) to reveal subtle conformational changes to DNA base and backbone structures. Such alterations to the molecular structure can change or disrupt gene expression.

 

The team identified a unique oxidation-induced lesion in the DNA of breast epithelium, myoepithelium and stroma and found that the highest concentrations of this lesion tended to occur in women in the 33- to 46-years age group, a bracket that corresponds to a known rise in the incidence of breast cancer. In a second paper, the team studied age-related concentrations of two similar mutagenic DNA lesions and again demonstrated that their occurrence is roughly commensurate with the age at which the incidence of female breast cancer rises. “Collectively,” they observe, “the findings reveal that the structural changes in DNA described may potentially disrupt normal reciprocal interactions between the cell types, thus increasing breast cancer risk.” The findings suggest that lesions measured in the DNA of the stroma, which is readily obtained, may prove to be convenient and sensitive biomarkers for assessing oxidative DNA damage and for signaling an increased breast cancer risk.

 

*K.M. Anderson, P. Jaruga, C.R. Ramsey, N.K. Gilman, V.M. Green, S.W. Rostad, J.T. Emerman, M. Dizdaroglu and D.C. Malins. Structural Alterations in Breast Stromal and Epithelial DNA: The Influence of 8,5'-Cyclo-2-Deoxyadenosine. Cell Cycle Vol. 5, No. 11, June 1, 2006, pp. 1240-1244.

 

D.C. Malins, K.M. Anderson, P. Jaruga, C.R. Ramsey, N.K. Gilman, V.M. Green, S.W. Rostad, J.T. Emerman and M. Dizdaroglu. Oxidative Changes in the DNA of Stroma and Epithelium from the Female Breast: Potential Implications for Breast Cancer. Cell Cycle Vol 5, No. 15, Aug. 1, 2006, pp. 1629-1632.

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

 

 

NIST Makes Changes to Key Security Publication

The National Institute of Standards and Technology (NIST) is requesting comments on a draft revision of Recommended Security Controls for Federal Information Systems (NIST Special Publication 800-53). Issued in February 2005, SP 800-53 is one of the key standards and guidelines developed by NIST to help federal agencies improve their security and comply with the Federal Information Security Management Act (FISMA). 

The publication recommends management, operational and technical controls needed to protect the confidentiality, integrity and availability of federal information systems. The controls cover 17 security focus areas, including risk assessment, contingency planning, access control and incident response. The draft changes include new and enhanced controls and additional guidance on implementing security controls in external environments and responding to information system incidents.   

 

These proposed changes reflect the first of what will be a biennial review and update cycle for SP 800-53.  “It is important to ensure that the security controls represent the current state-of-the-practice in safeguards and countermeasures for information systems. These changes will help federal agencies and others effectively select and specify security controls for their information systems, and by using a risk-based approach, do so in a cost-effective manner,” says Ron Ross, leader of NIST’s FISMA implementation project.

 

The draft document is available at http://csrc.nist.gov/publications/drafts.html#sp800-53-Rev1. Comments on the revisions will be accepted through Aug. 25, 2006, and should be sent to NIST, Computer Security Division, 100 Bureau Drive, Mail Stop 8930, Gaithersburg, MD 20899-8930 or via e-mail to sec-cert@nist.gov.

Media Contact:
Jan Kosko, kosko@nist.gov, (301) 975-2767

 

Quick Links

Workshop Addresses Imaging Technology in Therapeutics

Increasingly, medical and pharmaceutical researchers are looking to biomedical imaging as a tool to track disease progress, speed drug discovery and improve patient outcomes. The goal is to transform medical imaging technologies—X-rays, computer tomography (CT), magnetic resonance imaging (MRI), positron emission tomography (PET), magnetic resonance spectroscopy (MRS) and others—from qualitative pictures to quantitative biomarkers that can measure changes in tumors or other medical factors over time.

Recent work has shown that biomedical imaging can provide an early indication of drug response, but there are many sources of uncertainty that limit the quantitative use of imaging as a biomarker. These include variables in the image data collection platform, and the robustness of software tools required for reliable, quantitative measurement of subtle changes such as tumor volume, radioactive tracer activity or contrast agent dynamics. The development of standards for image quality control, image data collection and benchmarking of change analysis software tools, as well as image-specific statistical methods, could significantly reduce the size and cost of clinical trials for drug response.

 

The National Institute of Standards and Technology (NIST) will host a two-day workshop, Sept. 14-15, 2006, in Gaithersburg, Md., to assess the need for standardizing imaging methods for data collection and data analysis in drug or radiation therapy trials. The workshop, “Imaging as a Biomarker: Standards for Change Measurements in Therapy,” is co-sponsored by the National Institutes of Health, the Food and Drug Administration, the Pharmaceutical Research and Manufacturers of America, and the Radiological Society of North America, and several industry and technical associations. The cost to attend is $75. Additional details, including an agenda and complete list of sponsors, are available at http://usms.nist.gov/workshops/bioimaging.htm.

 

The workshop is one of a series on the U.S. Measurement System (USMS) convened by NIST to assess and document the nation's priority measurement and measurement-related standards needs for technological innovation, U.S. industrial competitiveness, safety and security, and quality of life.

 

 

Two NIST Researchers Earn Presidential Honors

 

The White House has announced that two researchers at the National Institute of Standards and Technology (NIST) are among the 56 recipients of the 2005 Presidential Early Career Awards for Scientists and Engineers (PECASE), the nation's highest honor for professionals at the outset of their independent research careers. James Vincent Porto III of the Atomic Physics Division of the NIST Physics Laboratory was honored for his research on neutral-atom quantum computing and novel quantum properties of atoms in one-dimensional systems, as well as for serving as a mentor to students, postdoctoral fellows, and other researchers. Christopher Lloyd Soles of the Polymers Division of the NIST Materials Science and Engineering Laboratory was recognized for development of measurement methods that provide scientific insight into the properties of materials confined within thin films and nanoscale structures, and for leadership in forging collaborations between government, industry, and universities.

 

Participating agencies award recipients up to five years of funding to further their research in support of critical government missions. For more information, see http://www.ostp.gov/html/pr_2006_PECASE%20Release.pdf.

 

ANSI Exec Will Help Iraq with Standards

NIST has engaged David Karmol, vice president for public policy and government affairs at the American National Standards Institute, to help the new Iraqi government build a coherent system of standards and procedures for determining whether products meet requirements. During his one-year assignment in Baghdad, Karmol will provide technical assistance to the Central Organization for Standardization and Quality Control, Iraq’s national standards body, and he will advise the Ministry of Housing and Development and other government departments that make extensive use of standards. NIST is responsible for identifying U.S. standards experts who could assist Iraq as it strengthens its standards system, now a varied assortment of elements from different nations. Karmol, who joined the NIST staff, arrived in Baghdad on July 31. For more, go to: http://www.ansi.org/news_publications/news_story.aspx?menuid=7&articleid=1214

 

 

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Editor: Michael Baum

Date created: 8/3/06
Date updated: 8/3/06
Contact: inquiries@nist.gov