The Geological Society of America goes 3D

I think the title says it all …

The release:

GSA Press Release – October 2010 Geosphere Highlights

Boulder, CO, USA – This month’s themed issue, “Advances in 3D imaging and analysis of geomaterials,” edited by Guilherme A.R. Gualda, Don R. Baker, and Margherita Polacci, features papers from the 2009 AGU Joint Assembly session “Advances in 3-D Imaging and Analysis of Rocks and Other Earth Materials.” Studies include 3-D imaging and analysis techniques for Wild 2 comet material returned from the NASA Stardust mission and the first 3-D X-ray scans of crystals from the Dry Valleys, Antarctica.

Keywords: Voxels, microtomography, fractures, NASA Stardust Mission, Wild 2, aerogel, Dry Valleys, Antarctica, geophysics, microearthquakes, Mexico, zircon dating, database, InSAR.

Highlights are provided below. Review abstracts for this issue at http://geosphere.gsapubs.org/.

Non-media requests for articles may be directed to GSA Sales and Service, gsaservice@geosociety.org .

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Introduction: Advances in 3D imaging and analysis of geomaterials
Guilherme A.R. Gualda, Vanderbilt University, Earth & Environmental Sciences, Station B #35-1805, Nashville, Tennessee 37235, USA

Excerpt: Beginning in the 1970s, the availability of computers led to the development of procedures for computer-assisted acquisition and reconstruction of 3-D tomographic data, in particular using X-rays. X-ray tomography is now a mature technique that is used routinely. It has been applied to a wide array of geomaterials, from rocks to fossils to diverse experimental charges, to name a few. The ability to create 3-D maps with millions to billions of volume elements (voxels) created the challenge of processing and analyzing such large amounts of data. While qualitative observations in 3-D yield significant insights into the nature of geomaterials and geological processes, it is in the pursuit of quantitative data that 3-D imaging shows its greatest potential. The continued improvements in computer capabilities have led to ever more sophisticated procedures for 3D image analysis. The papers in this issue encompass a wide range of topics, from applications of established techniques to a variety of materials, the development of new imaging techniques, and the description of improved imaging and analysis techniques.

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3D imaging of volcano gravitational deformation by computerized X-ray micro-tomography
M. Kervyn et al., Dept. of Geology and Soil Science, Ghent University, Krijgslaan 281/S8, 9000 Gent, Belgium

Volcanoes are known to be unstable constructs that can deform gravitationally when they build upon weak sedimentary layers. The structures and velocity of deformation depend on the volcano loading and the properties of the underlying layers. These processes can be studied with scaled laboratory experiments in which volcanoes are simulated by a mixture of sand and plaster. Silicone is used to simulate the weak underlying layers. This team from Belgium and France, lead by M. Kervyn of Ghen University, presents the results of imaging such experiments with X-rays. The micro-tomography technology used in imaging these experiments enables the virtual re-construction of the 3-D shape of the deformed experiment. Virtual cross-sections through the experiment provide a new way to characterize the faults and fissures forming within the experimental volcano during its deformation. Results from a range of experiments with different geometrical characteristics provide a better understanding of the impact of such gravitational deformation, currently recorded at several well-known volcanoes on Earth (e.g. Etna, Kilauea), on the construct’s structure at depth and its potential zones of weakness.

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Three-dimensional measurement of fractures in heterogeneous materials using high-resolution X-ray computed tomography
Richard A. Ketcham et al., Dept. of Geological Sciences, Jackson School of Geosciences, 1 University Station C1100, The University of Texas at Austin, Austin, Texas 78712-0254, USA

When present, fractures tend to dominate fluid flow though rock bodies, and characterizing fracture networks is necessary for understanding these flow regimes. Specialized CAT scanning has long been an important tool in imaging fractures in 3-D in rock samples. However, a number of factors have reduced the fidelity of such data, including the natural heterogeneity of real rocks and the limited resolution of CAT scanning. Richard A. Ketcham of The University of Texas at Austin and colleagues present new, general methods for overcoming these problems and extracting the best-quality information possible concerning fracture aperture, roughness, and orientation, even in highly heterogeneous rocks. The methods are also general enough that they can be applied to similar situations, such as measuring mineral veins. This work was funded in part by U.S. National Science Foundation grants EAR-0113480 and EAR-0439806.

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Laser scanning confocal microscopy of comet material in aerogel
Michael Greenberg and Denton S. Ebel, Dept. of Earth and Planetary Sciences, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024, USA

The NASA Stardust mission returned extraterrestrial material from the comet Wild 2 — the first solid sample-return mission since the Apollo era. Particles from the tail of Wild 2 were captured in aerogel, low-density, translucent, silica foam at a relative velocity of 6.1 km per second. Upon impact into the aerogel, particles from the tail of the comet were fragmented, melted, and ablated, creating cavities, or tracks — each of which is unique to the original particle before capture. Michael Greenberg and Denton S. Ebel of the American Museum of Natural History present nondestructive 3-D imaging and analysis techniques for comet material returned from the NASA Stardust mission. The methods described in this paper represent the highest resolution 3-D images of Stardust material to date. The procedures described here will easily extend to other translucent samples in the geosciences.

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Media tips from the American Chemical Society

Just passing these along — enjoy as you see fit.

The release:

ACS Weekly PressPac — Feb. 11, 2009

Here is the latest American Chemical Society (ACS) Weekly PressPac from the Office of Public Affairs. It has news from ACS’ 34 peer-reviewed journals and Chemical & Engineering News. Please credit the individual journal or the American Chemical Society as the source for this information.

		IMAGE: This is a photo of the charcoal combustion heater that Japanese scientists say will offer cleaner, more efficient home heating. Click here for more information.

New biomass heater: A “new era” of efficiency and sustainability
Industrial & Engineering Chemistry Research Millions of homes in rural areas of Far Eastern countries are heated by charcoal burned on small, hibachi-style portable grills. Scientists in Japan are now reporting development of an improved “biomass charcoal combustion heater” that they say could open a new era in sustainable and ultra-high efficiency home heating. Their study was published in ACS’ Industrial & Engineering Chemistry Research, a bi-weekly journal.

In the study, Amit Suri, Masayuki Horio and colleagues note that about 67 percent of Japan is covered with forests, with that biomass the nation’s most abundant renewable energy source. Wider use of biomass could tap that sustainable source of fuel and by their calculations cut annual carbon dioxide emissions by 4.46 million tons.

Using waste biomass charcoal, their heater recorded a thermal efficiency of 60-81 percent compared to an efficiency of 46-54 percent of current biomass stoves in Turkey and the U.S. “The charcoal combustion heater developed in the present work, with its fast startup, high efficiency, and possible automated control, would open a new era of massive but small-scale biomass utilization for a sustainable society,” the authors say. – JS

ARTICLE #1 FOR IMMEDIATE RELEASE
“Development of Biomass Charcoal Combustion Heater for Household Utilization”

DOWNLOAD FULL TEXT ARTICLE:
http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ie8006243

 

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ARTICLE #2 FOR IMMEDIATE RELEASE

Antibacterial plaster could put a clean sheen on walls
Crystal Growth & DesignScientists in China are reporting development and testing of new self-sanitizing plaster with more powerful antibacterial effects than penicillin. The material could be used in wall coatings, paints, art works and other products. The study is in the current issue of ACS’ Crystal Growth & Design, a bi-monthly journal.

Liang-jie Yuan and colleagues note that plaster has been used for centuries as building material and surfaces for great works of art, including Michelangelo’s famed Sistine Chapel ceiling in Vatican City. The new, first-of-its kind plaster —formed from different ingredients from traditional gypsum plaster — still retains similar mechanical properties while having added antibacterial effects.

Lab tests showed that the so-called “supramolecular” plaster has a “very broad” antibacterial spectrum, killing five types of disease-causing bacteria. When compared with penicillin, the plaster was more effective at controlling growth of four kinds of bacteria, including dangerous Staphylococcus aureus and Escherichia coli. “It can be expected that the supramolecular plaster can be used for building, painting, coating and carving, and the coat, brick, or art ware constructed by the plaster do not need additive antiseptic or sterilization,” the authors say. – JS

ARTICLE #2 FOR IMMEDIATE RELEASE
“A Novel Supramolecular Plaster Based on An Organic Acid-Base Compound: Synthesis, Structure, Mechanical Properties, and Sterilizing Performance”

DOWNLOAD FULL TEXT ARTICLE:
http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/cg800552s

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		IMAGE: Materials from printed circuit boards used in electronics, such as computers and cell phones, could be used to strengthen asphalt paving, scientists report. Above is a micrograph of the modified… Click here for more information.

Information superhighway’s trash yields a super highway asphalt
Environmental Science & TechnologyDiscarded electronic hardware, including bits and pieces that built the information superhighway, can be recycled into an additive that makes super-strong asphalt paving material for real highways, researchers in China are reporting in a new study. It is scheduled for the Feb. 1 issue of ACS’ Environmental Science & Technology, a semi-monthly journal. They describe development of a new recycling process that can convert discarded electronic circuit boards into an asphalt “modifier.” The material makes high-performance paving material asphalt that is cheaper, longer lasting, and more environmentally friendly than conventional asphalt, the scientists report.

In the new study, Zhenming Xu and colleagues note that millions of tons of electronic waste (e-waste) pile up each year. The printed circuit boards used in personal computers, cell phones, and other electronic gear, contain toxic metals such as lead and mercury and pose a difficult disposal problem. The boards also are difficult to recycle. Xu’s group, however, realized that the boards, which provide mechanical support and connections for transistors and other electronic components, contain glass fibers and plastic resins that could strengthen asphalt paving.

The scientists describe a new recycling method that quickly separates toxic metals from circuit boards, yielding a fine, metal-free powder. When mixed into asphalt in laboratory tests, the powder produced a stronger paving material less apt to soften at high temperatures, the researchers say. -MTS

ARTICLE #3 FOR IMMEDIATE RELEASE
“Asphalt Modified with Nonmetals Separated from Pulverized Waste Printed Circuit Boards”

DOWNLOAD FULL TEXT ARTICLE:
http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/es8023012

 

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		IMAGE: Aerogels, a super-lightweight solid sometimes called “frozen smoke, ” may capture oil from wastewater and soak up environmental oil spills. Click here for more information.

“Frozen smoke:” The ultimate sponge for cleaning up oil spills
Industrial & Engineering Chemistry ResearchScientists in Arizona and New Jersey are reporting that aerogels, a super-lightweight solid sometimes called “frozen smoke,” may serve as the ultimate sponge for capturing oil from wastewater and effectively soaking up environmental oil spills. Their study is in ACS’ Industrial & Engineering Chemistry Research, a bi-weekly journal.

In the new study, Robert Pfeffer and colleagues point out that the environmental challenges of oil contamination go beyond widely publicized maritime oil spills like the Exxon Valdez incident. Experts estimate that each year people dump more than 200 million gallons of used oil into sewers, streams, and backyards, resulting in polluted wastewater that is difficult to treat. Although there are many different sorbent materials for removing used oil, such as activated carbon, they are often costly and inefficient. Hydrophobic silica aerogels are highly porous and absorbent material, and seemed like an excellent oil sponge.

The scientists packed a batch of tiny aerogel beads into a vertical column and exposed them to flowing water containing soybean oil to simulate the filtration process at a wastewater treatment plant. They showed that the aerogel beads absorbed up to 7 times their weight and removed oil from the wastewater at high efficiency, better than many conventional sorbent materials. – MTS

ARTICLE #4 FOR IMMEDIATE RELEASE
“Removal of Oil from Water by Inverse Fluidization of Aerogels”

DOWNLOAD FULL TEXT ARTICLE:
http://pubs.acs.org/stoken/presspac/presspac/full/10.1021/ie800022e

 

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ARTICLE #5 EMBARGOED FOR 9 A.M., EASTERN TIME, Feb. 16, 2009

Greener pesticides, better farming practices help reduce U.S. pesticide use
Chemical & Engineering NewsAlthough few consumers realize it, fruits, veggies, and other agricultural products marketed in the United States today are grown on farms that use less pesticide than 30 years ago, according to an article scheduled for the Feb. 16 issue of Chemical & Engineering News, ACS’ weekly newsmagazine.

C&EN Senior Editor Stephen K. Ritter points out in the magazine’s cover story that pesticide use has dropped in the U.S. due to more efficient pesticides and better agricultural practices. Pesticide use peaked at 1.46 billion pounds in 1979 and fell to 1.23 billion pounds in 2001 — the last year for which comprehensive data are available, according to the Environmental Protection Agency. Since then pesticide use has remained at those lower levels, the article states.

Several innovations are responsible for this decline in pesticide use, including better, more selective pesticides that can be applied at lower rates while having less impact on human health and the environment. Other factors include a farming practice called integrated pest management (IPM), which involves withholding the use of synthetic pesticides only until damage reaches a certain threshold. In addition, farmers also are using more so-called biopesticides. These natural substances, derived from plants, microorganisms, and insects, can combat noxious weeds, insects, and fungi with less harm to crops and the environment.

ARTICLE #5 EMBARGOED FOR 9 A.M., EASTERN TIME, Feb. 16, 2009
“Greening The Farm”

This story will be available on Feb. 16 at
http://pubs.acs.org/cen/coverstory/87/8707cover.html

 

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The American Chemical Society — the world’s largest scientific society — is a nonprofit organization chartered by the U.S. Congress and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.

ARTICLE #4 FOR IMMEDIATE RELEASE

ARTICLE #3 FOR IMMEDIATE RELEASE

ARTICLE #1 FOR IMMEDIATE RELEASE

Looking inside aerogels

Aerogels are pretty amazing substances with many uses. This press release covers using X-ray diffraction to get a 3D nanoscale look inside aerogels.

The full release and two of the provided images:

X-Ray Diffraction Looks Inside Aerogels in 3-D

A multi-institutional team of scientists has used beamline 9.0.1 at the Advanced Light Source to perform high-resolution x‑ray diffraction imaging of an aerogel for the first time, revealing its nanoscale three-dimensional bulk lattice structure down to features measured in nanometers, billionths of a meter.

Aerogels, sometimes called “frozen smoke” or “San Francisco fog,” are nanoscale foams: solid materials whose sponge-like structure is riddled by pores as small as nanometers across and whose strength is surprising, given their low density. Many porous materials are extraordinary for their properties as insulators, filters, and catalysts; they are used to produce clean fuels, to insulate windows and even clothing, to study the percolation of oil through rock, as drug-delivery systems, and even to cushion the capture of high-velocity comet fragments in outer space.

“The smallest pore size is the key to the strength of porous materials and what they can do,” says Stefano Marchesini, an ALS scientist at Berkeley Lab, who led the research. “Seeing inside bulk porous materials has never been done before at this resolution, making this one of the first applications of x-ray diffractive microscopy to a real problem.” 

Team members from Lawrence Livermore National Laboratory, the University of California at Davis, Arizona State University, Argonne National Laboratory, and Berkeley Lab performed the x‑ray diffraction imaging and have published their results online in Physical Review Letters, available to subscribers at http://link.aps.org/abstract/PRL/v101/e055501.

Seeing inside foam

One way to study aerogels and other nanofoams is with electron microscopy, which can image only thin, two-dimensional slices through the porous structure of the material. Another method is straightforward x-ray microscopy, using zone plates as “lenses”; microscopy can penetrate a sample but has difficulty maintaining resolution at different depths in the material. Small-angle x‑ray scattering (SAXS) can also gather limited structural information from finely powdered aerogels, but SAXS cannot provide full three-dimensional information. None of these techniques can capture the 3-D internal structure of nanofoam samples measured in micrometers, a few millionths of a meter across.

X-ray diffraction approaches the problem differently. A laser-like x-ray beam passes all the way through the sample and is diffracted onto a CCD detector screen; diffraction patterns are repeatedly stored while the sample is moved and rotated. A typical series requires approximately 150 views in all.

The individual diffraction patterns are then processed by a computer. The way the photons in the beam are redirected from each component of the structure is different for each orientation, and comparing their intensities serves to position that component precisely in three-dimensional space. Thousands of iterations are required – in the present study, team member Anton Barty of Livermore led the solution of almost 100 million measured intensities, as opposed to the 100 thousand or so typical of, say, protein crystallography – but the end result is a 3‑D image of the tiny sample at nanometer-scale resolution.

Foam-like structures are described in terms of interconnecting lattice beams and the nodes where they intersect. These elements became vividly apparent in the reconstructed 3-D images of the aerogel used in the imaging at the ALS, which was made of tantalum ethoxide (Ta₂O₅), a ceramic material proposed for cladding capsules of hydrogen isotopes for inertial-confinement fusion experiments being pursued at Livermore.

“The strength and stiffness of foam-like structures are expected to scale with their density, relating the density of individual elements like beams and nodes to the overall density,” Marchesini says. “But below about 10 percent density, the strength of aerogels like the ones we tested – on the order of 1 percent density – is orders of magnitude less than expected.”

Of the theories that seek to explain this phenomenon, one is the “percolation” model, in which fragments become detached from the load-bearing structure and add mass without contributing to strength. The alternate “heterogeneities” model proposes that the structure is increasingly riddled with defects like micron-sized holes and buckles more easily.

A third theory is the “diffusion-limited cluster aggregation” model: blobs of material accumulate that are connected by thin links, instead of sturdy beams between nodes.

“The high resolution we achieved allowed us to see which of these models more accurately described the actual observed structure,” Marchesini says. By seeing the foam from the inside, the team was able to see exactly how it was structured, and the shape and dimensions of each component. “The structure was far more complex than anything we’d seen in earlier images obtained using this technique.”

What the team observed in their 3-D images of the tantalum ethoxide aerogel was a “blob-and-beam” structure consistent with the third model, that of diffusion-limited cluster aggregation. The observed structure explained the relative weakness of the low-density material and also suggested that changes in methods of preparing aerogels might improve their strength.

Into the future

“We’d like to use x-ray diffraction to study a range of porous materials and nanostructures in general, for example porous polymers developed at the Molecular Foundry for storing hydrogen as fuel – and at even higher resolutions,” Marchesini says. “To do so, David Shapiro, who built the end station we used for this work, is working with us to overcome some obstacles.”

One is time. At present, each sample takes months of work. After preparation, the experiment first requires one or two days of mounting, rotating, and exposing the sample to the x-ray beam, about a minute per view – because of a slow detector – for 150 views. There follow weeks of computation time. “And after all this, you can find out the sample was no good, so you have to start over,” Marchesini says.

Improved sample handling, faster detectors, and a beamline dedicated to x-ray diffraction are principal goals. The Coherent Scattering and Diffraction Microscopy (COSMIC) facility, a top priority in the ALS strategic plan, will provide intense coherent x-rays with full polarization control.

“We are also collaborating with Berkeley Lab’s Computational Research Division to develop efficient and robust algorithms to speed up the time needed to construct the 3-D image from the individual rotated views,” Marchesini says. “This will open an entire spectrum of possibilities for new ways of seeing the very small – not just aerogels but virtually any unknown object, from nanostructures to biological cells.”

This work was principally supported by the Department of Energy through a variety of grants, by Laboratory Directed Research and Development programs at Livermore, and additionally by the National Science Foundation.

Additional information

• “Three-dimensional coherent X-ray diffraction imaging of a ceramic nanofoam: determination of structural deformation mechanisms,” by A. Barty, S. Marchesini, H. N. Chapman, C. Cui, M. R. Howells, D. A. Shapiro, A. M. Minor, J. C. H. Spence, U. Weierstall, J. Havsky, A. Noy, S. P. Hau-Riege, A. B. Artyukhin, T. Baumann, T. Willey, J. Stolken, T. van Buuren, and J. H. Kinney, appears in Physical Review Letters online publication and is available to subscribers at http://link.aps.org/abstract/PRL/v101/e055501.
• More about beamline 9.0.1 at the Advanced Light Source

Silicon aerogel acting as an insulator

 

A 500-nanometer cube of aerogel from the interior of the 3-D volume, reconstructed by x-ray diffraction. The foam structure shows globular nodes that are interconnected by thin beam- like struts. Approximately 85 percent of the total mass is associated with the nodes; relatively little of the mass is in the load-bearing links.