David Kirkpatrick

April 8, 2010

All nanotech isn’t sexy

Sometimes it’s just about making an existing process a little better. Of course it’s a lot more fun to blog about game-changers and the medical breakthroughs.

The release:

Scientists develop environmentally friendly way to produce propylene oxide using silver nanoclusters

Scientists at the U.S. Department of Energy’s Argonne National Laboratory have identified a new class of silver-based catalysts for the production of the industrially useful chemical propylene oxide that is both environmentally friendly and less expensive.

“The production of propylene oxide has a significant amount of by-products that are harmful to the environment, including chlorinated or peroxycarboxylic waste,” said chemist Stefan Vajda of Argonne’s Materials Science Division and Center for Nanoscale Materials. “We have identified nanoclusters of silver as a catalyst that produce this chemical with few by-products at low temperatures.”

Propylene oxide is commonly used in the creation of plastics and propylene glycols for paints, household detergents and automotive brake fluids.

The study is a result of a highly collaborative team that involved five Argonne Divisions and collaborators from the Fritz-Haber-Institut in Berlin and from the University of Illinois in Chicago, including a collaboration between the experimental effort led by Stefan Vajda and the theoretical analysis led by materials chemist Larry Curtiss and nanoscientist Jeff Greeley.

Large silver particles have been used to produce propylene oxide from propylene, but have suffered from a low selectivity or low conversion to propylene oxide, creating a large amount of carbon dioxide. Vajda discovered that nanoscale clusters of silver, consisting of both three atoms as well as larger clusters of 3.5 nanometers in size, are highly active and selective catalysts for the production of propylene oxide.

Curtiss and Greeley then modeled the underlying mechanism behind why these ultrasmall nanoparticles of silver were so effective in creating propylene oxide. They discovered that the open shell electronic structure of the silver catalysts was the impetus behind the nanoclusters selectivity.

“Propylene oxide is a building block in the creation of several other industrially relevant chemicals, but the current methods of creating it are not efficient,” Curtiss said.

“This is basically a holy grail reaction,” remarked Greeley. “The work opens a new chapter in the field of silver as a catalyst for propene epoxidation,” added Curtiss.

###

Funding for this project was from the U.S. Department of Energy Office of Science and from the U.S. Air Force Office of Scientific Research. A paper on this work will be published in the April 9 issue of the journal Science.

The Center for Nanoscale Materials at Argonne National Laboratory is one of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale, supported by the DOE Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative. The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos National Laboratories. For more information about the DOE NSRCs, please visit http://nano.energy.gov.

The U.S. Department of Energy’s Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

Photos are available at http://www.flickr.com/photos/argonne/4502854661/ and http://www.flickr.com/photos/argonne/4503484446/

November 29, 2009

Nanomagnet cancer treatment

Nanoscale magnetic discs actually physically wreck cancer cells. Nanotech is offering a lot of medical treatments, particularly in cancer research.

From the link:

Laboratory tests found the so-called “nanodiscs”, around 60 billionths of a metre thick, could be used to disrupt the membranes of , causing them to self-destruct.

The discs are made from an iron-nickel alloy, which move when subjected to a magnetic field, damaging the cancer cells, the report published in Nature Materials said.

One of the study’s authors, Elena Rozhlova of Argonne National Laboratory in the United States, said subjecting the discs to a low magnetic field for around ten minutes was enough to destroy 90 percent of cancer cells in tests.

August 2, 2008

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

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.
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.

April 16, 2008

Molecular movie stars, stem cells and quantum computing

Nice roundup from KurzweilAI.net today.

First up is nngews on a more accurate method for creating movies of molecular and biological processes

Keeping with the biology theme is a breakthrough for treating heart damage with stem cells.

Finishing the group is a bit about progress toward a quantum computer.

Movies of biological and chemical molecules made for first time
KurzweilAI.net, April 16, 2008Argonne National Laboratory scientists have developed accurate techniques for making movies of actual biological and chemical molecules for the first time.


X-ray movie reveals movement of DNA molecule

Biological and organic molecules in solution are far more complex than the standard crystalline structures of salt or metals since they are constantly moving and changing over time.

Using the high-intensity X-rays at the Advanced Photon Source, the scientists have measured images that are blurred by these motions and used computer processing algorithms to create more accurate movies of the molecular motions.

Source: Argonne scientists develop techniques for creating molecular movies

 

Molecule prompts blood stem cells to help repair heart damage in animal model
PhysOrg.com, April 15, 2008University of Texas Southwestern Medical Center researchers used drug-treated blood stem cells to repair heart damage in an animal model.

They screened about 147,000 molecules to find one that could transform human blood stem cells into a form resembling immature heart cells. When they implanted blood stem cells activated by this compound into injured rodent hearts, the human cells took root and improved the animals’ heart function.

 
Read Original Article>>

 

Toward a Quantum Internet
Technology Review, April 15, 2008Northwestern University researchers have build a quantum logic gate–a fundamental component of a quantum computer–within an optical fiber, using entangled photon pairs.

The gate could be part of a circuit that relays information securely, over hundreds of kilometers of fiber, from one quantum computer to another. It could also be used on its own to find solutions to complicated mathematical problems.

 
Read Original Article>>

April 2, 2008

Hydrogen fuel news

Even more from KurzweilAI.net today — two bits on improving hydrogen as a fuel source.

The first outlines research that found hydrogen can be stored in nanoparticles making the fuel source potentially much more mobile.

The second link covers algae as a source of hydrogen fuel.

Hydrogen Storage In Nanoparticles Works: Outlook For Hydrogen Cars Improved
Science Daily, April 1, 2008Dutch chemist Kees Balde has discovered that 30-nanometer particles of the metal hydride sodium alanate make storage and release of hydrogen possible, allowing for it to be more easily used in mobile applications.

With the addition of a titanium catalyst, a further reduction in the particle size to 20 nanometers is possible, allowing for even more efficient storage of hydrogen.
Read Original Article>>

Algae as a hydrogen fuel source
KurzweilAI.net, April 2, 2008Argonne National Laboratory scientists are engineering algae’s photosynthesis process to produce hydrogen gas by adding the enzyme hydrogenase.

Algae that naturally have hydrogenase produce only small volumes of hydrogen. With the enzyme added to photosynthesis the algae should produce as much hydrogen as oxygen.

See Also Algae-Based Fuels Set to Bloom

DOE/Argonne National Laboratory News Release

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