David Kirkpatrick

May 12, 2010

Semi-conductor nanocrystals and quantum computing

Another step toward quantum computing.

The release:

Quantum move toward next generation computing

McGill researchers make important contribution to the development of quantum computing

This release is available in French.

IMAGE: These images show the electrostatic energy given off when electrons are added to a quantum dot. They were made with an atomic-force microscope.

Click here for more information.

Physicists at McGill University have developed a system for measuring the energy involved in adding electrons to semi-conductor nanocrystals, also known as quantum dots – a technology that may revolutionize computing and other areas of science. Dr. Peter Grütter, McGill’s Associate Dean of Research and Graduate Education, Faculty of Science, explains that his research team has developed a cantilever force sensor that enables individual electrons to be removed and added to a quantum dot and the energy involved in the operation to be measured.

Being able to measure the energy at such infinitesimal levels is an important step in being able to develop an eventual replacement for the silicon chip in computers – the next generation of computing. Computers currently work with processors that contain transistors that are either in an on or off position – conductors and semi-conductors – while quantum computing would allow processors to work with multiple states, vastly increasing their speed while reducing their size even more.

Although popularly used to connote something very large, the word “quantum” itself actually means the smallest amount by which certain physical quantities can change. Knowledge of these energy levels enables scientists to understand and predict the electronic properties of the nanoscale systems they are developing.

“We are determining optical and electronic transport properties,” Grütter said. “This is essential for the development of components that might replace silicon chips in current computers.”

IMAGE: These images show the electrostatic energy given off when electrons are added to a quantum dot. They were made with an atomic-force microscope.

Click here for more information.

The electronic principles of nanosystems also determine their chemical properties, so the team’s research is relevant to making chemical processes “greener” and more energy efficient. For example, this technology could be applied to lighting systems, by using nanoparticles to improving their energy efficiency. “We expect this method to have many important applications in fundamental as well as applied research,” said Lynda Cockins of McGill’s Department of Physics.

The principle of the cantilever sensors sounds relatively simple. “The cantilever is about 0.5 mm in size (about the thickness of a thumbnail) and is essentially a simple driven, damped harmonic oscillator, mathematically equivalent to a child’s swing being pushed,” Grütter explained. “The signal we measure is the damping of the cantilever, the equivalent to how hard I have to push the kid on the swing so that she maintains a constant height, or what I would call the ‘oscillation amplitude.’ ”

Dr. Aashish Clerk, Yoichi Miyahara, and Steven D. Bennett of McGill’s Dept. of Physics, and scientists at the Institute for Microstructural Sciences of the National Research Council of Canada contributed to this research, which was published online late yesterday afternoon in the Proceedings of the National Academy of Sciences. The research received funding from the Natural Sciences and Engineering Research Council of Canada, le Fonds Québécois de le Recherche sur la Nature et les Technologies, the Carl Reinhardt Fellowship, and the Canadian Institute for Advanced Research.

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May 1, 2010

Quantum computing news

I wouldn’t call this an astounding breakthrough, but sometimes a shift in focus — like this research into alternative materials for quantum computers — can lead to seismic changes in the field down the road.

The release:

UCSB scientists look beyond diamond for quantum computing

IMAGE: David Awschalom is a researcher at University of California – Santa Barbara.

Click here for more information.

(Santa Barbara, Calif.) –– A team of scientists at UC Santa Barbara that helped pioneer research into the quantum properties of a small defect found in diamonds has now used cutting-edge computational techniques to produce a road map for studying defects in alternative materials.

Their new research is published in the online edition of the Proceedings of the National Academy of Sciences (PNAS), and will soon be published in the print edition of the journal. The findings may enable new applications for semiconductors ––materials that are the foundation of today’s information technology. In particular, they may help identify alternative materials to use for building a potential quantum computer.

“Our results are likely to have an impact on experimental and theoretical research in diverse areas of science and technology, including semiconductor physics, materials science, magnetism, and quantum device engineering,” said David D. Awschalom, UCSB physics professor and one of two lead investigators on this project. “Ironically, while much of semiconductor technology is devoted to eliminating the defects that interfere with how today’s devices operate, these defects may actually be useful for future quantum technologies.”

IMAGE: Chris Van de Walle is a researcher at University of California – Santa Barbara.

Click here for more information.

According to PNAS, the researchers have developed a set of screening criteria to find specific atomic defects in solids that could act as quantum bits (qubits) in a potential quantum computer. As a point of reference, they use a system whose quantum properties they themselves have recently helped to discern, the NV or nitrogen-vacancy center defect in diamond. This defect, which the team has shown can act as a very fast and stable qubit at room temperature, consists of a stray nitrogen atom alongside a vacancy in the otherwise perfect stacking of carbon atoms in a diamond.

Electrons trapped at the defect’s center interact with light and microwaves in a predictable way, allowing information to be stored in and read out from the orientation of their quantum-mechanical spins.

The drawback to using diamond, however, is that the material is expensive and difficult to grow and process into chips. This raises the question of whether there may be defects in other materials that have similar properties and could perform equally well.

In this week’s publication, the researchers enumerate specific screening criteria to identify appropriate defects in materials that could be useful for building a quantum computer. Experimental testing of all the potential candidates might take decades of painstaking research, explained Awschalom. To address this problem, the UCSB group employed advanced computational methods to theoretically examine the characteristics of potential defect centers in many different materials, providing a sort of road map for future experiments.

UCSB’s Chris G. Van de Walle, professor of materials and one of the senior investigators on the project, remarked: “We tap into the expertise that we have accumulated over the years while examining ‘bad’ defects, and channel it productively into designing ‘good’ defects; i.e., those that have the necessary characteristics to equal or even outperform the NV center in diamond.” This expertise is backed up by advanced theoretical and computational models that enable the reliable prediction of the properties of defects, a number of which are proposed and examined in the paper.

Awschalom added: “We anticipate this work will stimulate additional collaborative activities among theoretical physicists and materials engineers to accelerate progress towards quantum computing based on semiconductors.”

Current computers are based on binary logic: each bit can be either “one” or “zero.” In contrast, each qubit in a quantum computer is continuously variable between these two states and hence offers infinitely more possibilities to be manipulated and combined with other qubits to produce a desired computational result. “It has been well established that, in theory, quantum computers can tackle some tasks that are completely beyond the capabilities of binary computers,” said Awschalom. “The challenge has been to identify real physical systems that can serve as qubits for future machines.”

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February 2, 2010

Spider man, spider man …

… does whatever a spider can.

I’ll just let the release from yesterday finish this thought process for me:

New adhesive device could let humans walk on walls

Could humans one day walk on walls, like Spider-Man? A palm-sized device invented at Cornell that uses water surface tension as an adhesive bond just might make it possible.

The rapid adhesion mechanism could lead to such applications as shoes or gloves that stick and unstick to walls, or Post-it-like notes that can bear loads, according to Paul Steen, professor of chemical and biomolecular engineering, who invented the device with Michael Vogel, a former postdoctoral associate.

The device is the result of inspiration drawn from a beetle native to Florida, which can adhere to a leaf with a force 100 times its own weight, yet also instantly unstick itself. Research behind the device is published online Feb. 1 in Proceedings of the National Academy of Sciences.

The device consists of a flat plate patterned with holes, each on the order of microns (one-millionth of a meter). A bottom plate holds a liquid reservoir, and in the middle is another porous layer. An electric field applied by a common 9-volt battery pumps water through the device and causes droplets to squeeze through the top layer. The surface tension of the exposed droplets makes the device grip another surface – much the way two wet glass slides stick together.

“In our everyday experience, these forces are relatively weak,” Steen said. “But if you make a lot of them and can control them, like the beetle does, you can get strong adhesion forces.”

For example, one of the researchers’ prototypes was made with about 1,000 300-micron-sized holes, and it can hold about 30 grams – more than 70 paper clips. They found that as they scaled down the holes and packed more of them onto the device, the adhesion got stronger. They estimate, then, that a one-square-inch device with millions of 1-micron-sized holes could hold more than 15 pounds.

To turn the adhesion off, the electric field is simply reversed, and the water is pulled back through the pores, breaking the tiny “bridges” created between the device and the other surface by the individual droplets.

The research builds on previously published work that demonstrated the efficacy of what’s called electro-osmotic pumping between surface tension-held interfaces, first by using just two larger water droplets.

One of the biggest challenges in making these devices work, Steen said, was keeping the droplets from coalescing, as water droplets tend to do when they get close together. To solve this, they designed their pump to resist water flow while it’s turned off.

Steen envisions future prototypes on a grander scale, once the pump mechanism is perfected, and the adhesive bond can be made even stronger. He also imagines covering the droplets with thin membranes – thin enough to be controlled by the pump but thick enough to eliminate wetting. The encapsulated liquid could exert simultaneous forces, like tiny punches.

“You can think about making a credit card-sized device that you can put in a rock fissure or a door, and break it open with very little voltage,” Steen said. “It’s a fun thing to think about.”

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The research was funded primarily by the Defense Advanced Research Projects Agency and also by the National Science Foundation.

October 20, 2009

Are we still evolving?

Of course.

The release:

Are humans still evolving? Absolutely, says a new analysis of a long-term survey of human health

Durham, NC – Although advances in medical care have improved standards of living over time, humans aren’t entirely sheltered from the forces of natural selection, a new study shows.

“There is this idea that because medicine has been so good at reducing mortality rates, that means that natural selection is no longer operating in humans,” said Stephen Stearns of Yale University. A recent analysis by Stearns and colleagues turns this idea on its head. As part of a working group sponsored by the National Evolutionary Synthesis Center in Durham, NC, the team of researchers decided to find out if natural selection — a major driving force of evolution — is still at work in humans today. The result? Human evolution hasn’t ground to a halt. In fact, we’re likely to evolve at roughly the same rates as other living things, findings suggest.

Taking advantage of data collected as part of a 60-year study of more than 2000 North American women in the Framingham Heart Study, the researchers analyzed a handful of traits important to human health. By measuring the effects of these traits on the number of children the women had over their lifetime, the researchers were able to estimate the strength of selection and make short-term predictions about how each trait might evolve in the future. After adjusting for factors such as education and smoking, their models predict that the descendents of these women will be slightly shorter and heavier, will have lower blood pressure and cholesterol, will have their first child at a younger age, and will reach menopause later in life.

“The take-home message is that humans are currently evolving,” said Stearns. “Natural selection is still operating.”

The changes may be slow and gradual, but the predicted rates of change are no different from those observed elsewhere in nature, the researchers say. “The evolution that’s going on in the Framingham women is like average rates of evolution measured in other plants and animals,” said Stearns. “These results place humans in the medium-to-slow end of the range of rates observed for other living things,” he added. “But what that means is that humans aren’t special with respect to how fast they’re evolving. They’re kind of average.”

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Additional authors on the study were Sean Byars of Yale University, Douglas Ewbank of the University of Pennsylvania, and Diddahally Govindaraju of Boston University.

The team’s findings were published online in the October 19th issue of Proceedings of the National Academy of Sciences.

CITATION: Byars, S., D. Ewbank, et al. (2009). “Natural selection in a contemporary human population.” Proceedings of the National Academy of Sciences 106(42). doi: 10.1073_pnas.0906199106.

The National Evolutionary Synthesis Center (NESCent) is an NSF-funded collaborative research center operated by Duke University, the University of North Carolina at Chapel Hill, and North Carolina State University.

July 8, 2009

No carbon plan at G-8 summit

Not really surprising given the global recession, among many other issues around climate change politics.

From the link:

The failure to establish specific targets on climate change underscored the difficulty in bridging longstanding divisions between the most developed countries like the United States and developing nations like China and India. In the end, people close to the talks said, the emerging powers refused to agree to the specific emissions limits because they wanted industrial countries to commit to midterm goals in 2020, and to follow through on promises of financial and technological help.

“They’re saying, ‘We just don’t trust you guys,’ ” said Alden Meyer of the Union of Concerned Scientists, an advocacy group based in the United States. “It’s the same gridlock we had last year when Bush was president.”

American officials said they still had made an important breakthrough because the G-8 countries within the negotiations agreed to adopt the 2050 reduction goals, even though the developing countries would not.

Of course if these guys would just listen to this carbon emmission plan out of Princeton University the world could be saved, or something like that.

(Head below the fold for the full Princeton release.) (more…)

June 12, 2009

Assembly with graphene

Interesting research on the properties of one of the more exciting nanotech materials out there.

The release:

Penn materials scientist finds plumber’s wonderland on graphene

IMAGE: This is an electron micrograph showing the formation of interconnected carbon nanostructures on a graphene substrate, which may be harnessed to make future electronic devices.

Click here for more information. 

PHILADELPHIA –- Engineers from the University of Pennsylvania, Sandia National Laboratories and Rice University have demonstrated the formation of interconnected carbon nanostructures on graphene substrate in a simple assembly process that involves heating few-layer graphene sheets to sublimation using electric current that may eventually lead to a new paradigm for building integrated carbon-based devices.

Curvy nanostructures such as carbon nanotubes and fullerenes have extraordinary properties but are extremely challenging to pick up, handle and assemble into devices after synthesis. Penn materials scientist Ju Li and Sandia scientist Jianyu Huang have come up with a novel idea to construct curvy nanostructures directly integrated on graphene, taking advantage of the fact that graphene, an atomically thin two-dimensional sheet, bends easily after open edges have been cut on it, which can then fuse with other open edges permanently, like a plumber connecting metal fittings.

The “knife” and “welding torch” used in the experiments, which were performed inside an electron microscope, was electrical current from a Nanofactory scanning probe, generating up to 2000°C of heat. Upon applying the electrical current to few-layer graphene, they observed the in situ creation of many interconnected, curved carbon nanostructures, such as “fractional nanotube”-like graphene bi-layer edges, or BLEs; BLE rings on graphene equivalent to “anti quantum-dots”; and nanotube-BLE assembly connecting multiple layers of graphene.

Remarkably, researchers observed that more than 99 percent of the graphene edges formed during sublimation were curved BLEs rather than flat monolayer edges, indicating that BLEs are the stable edges in graphene, in agreement with predictions based on symmetry considerations and energetic calculations. Theory also predicts these BLEs, or “fractional nanotubes,” possess novel properties of their own and may find applications in devices.

The study is published in the current issue of the journal Proceedings of the National Academy of Sciences. Short movies of the fabrication of these nanostructures can be viewed at www.youtube.com/user/MaterialsTheory.

Li and Huang observed the creation of these interconnected carbon nanostructures using the heat of electric current and a high-resolution transmission electron microscope. The current, once passed through the graphene layers, improved the crystalline quality and surface cleanness of the graphene as well, both important for device fabrication.

The sublimation of few-layer graphene, such as a 10-layer stack, is advantageous over the sublimation of monolayers. In few-layer graphene, layers spontaneously fuse together forming nanostructures on top of one or two electrically conductive, extended, graphene sheets.

During heating, both the flat graphene sheets and the self-wrapping nanostructures that form, like bilayer edges and nanotubes, have unique electronic properties important for device applications. The biggest obstacle for engineers has been wrestling control of the structure and assembly of these nanostructures to best exploit the properties of carbon. The discoveries of self-assembled novel carbon nanostructures may circumvent the hurdle and lead to new approach of graphene-based electronic devices.

Researchers induced the sublimation of multilayer graphene by Joule-heating, making it thermodynamically favorable for the carbon atoms at the edge of the material to escape into the gas phase, leaving freshly exposed edges on the solid graphene. The remaining graphene edges curl and often welded together to form BLEs. Researchers attribute this behavior to nature’s driving force to reduce capillary energy, dangling bonds on the open edges of monolayer graphene, at the cost of increased bending energy.

“This study demonstrates it is possible to make and integrate curved nanostructures directly on flat graphene, which is extended and electrically conducting,” said Li, associate professor in the Department of Materials Science and Engineering in Penn’s School of Engineering and Applied Science. “Furthermore, it demonstrates that multiple graphene sheets can be intentionally interconnected. And the quality of the plumbing is exceptionally high, better than anything people have used for electrical contacts with carbon nanotubes so far. We are currently investigating the fundamental properties of graphene bi-layer edges, BLE rings and nanotube-BLE junctions.”

 

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The study was performed by Li and Liang Qi of Penn, Jian Yu Huang and Ping Lu of the Center for Integrated Nanotechnologies at Sandia and Feng Ding and Boris I. Yakobson of the Department of Mechanical Engineering and Materials Science at Rice.

It was supported by the National Science Foundation, the Air Force Office of Scientific Research, the Honda Research Institute, the Department of Energy and the Office of Naval Research.

June 5, 2009

Nanotech testing heart disease

Release number three in the dump, this covers a medical application of nanotech.

The release:

Researchers test nanoparticle to treat cardiovascular disease in mice

IMAGE: This is an image of a multifunctional micelle designed by research team.

Click here for more information. 

(Santa Barbara, Calif.) –– Scientists and engineers at UC Santa Barbara and other researchers have developed a nanoparticle that can attack plaque –– a major cause of cardiovascular disease. The new development is described in a recent issue of the Proceedings of the National Academy of Sciences.

The treatment is promising for the eventual development of therapies for cardiovascular disease, which is blamed for one third of the deaths in the United States each year. Atherosclerosis, which was the focus of this study, is one of the leading causes of cardiovascular disease. In atherosclerosis, plaque builds up on the walls of arteries and can cause heart attack and stroke.

IMAGE: Matthew Tirrell is a researcher at University of California – Santa Barbara.

Click here for more information. 

“The purpose of our grant is to develop targeted nanoparticles that specifically detect atherosclerotic plaques,” said Erkki Ruoslahti, distinguished professor at the Burnham Institute for Medical Research at the University of California, Santa Barbara. “We now have at least one peptide, described in the paper, that is capable of directing nanoparticles to the plaques.”

The nanoparticles in this study are lipid-based collections of molecules that form a sphere called a micelle. The micelle has a peptide, a piece of protein, on its surface, and that peptide binds to the surface of the plaque.

Co-author Matthew Tirrell, The Richard A. Auhll Professor and dean of UCSB’s College of Engineering, specializes in lipid-based micelles. “This turned out to be a perfect fit with our targeting technology,” said Ruoslahti.

To accomplish the research, the team induced atherosclerotic plaques in mice by keeping them on a high-fat diet. They then intravenously injected these mice with the micelles, which were allowed to circulate for three hours.

IMAGE: Erkki Ruoslahti is a researcher at University of California – Santa Barbara.

Click here for more information. 

“One important element in what we did was to see if we could target not just plaques, but the plaques that are most vulnerable to rupture,” said Ruoslahti. “It did seem that we were indeed preferentially targeting those places in the plaques that are prone to rupture.”

The plaques tend to rupture at the “shoulder,” where the plaque tissue meets the normal tissue. “That’s also a place where the capsule on the plaque is the thinnest,” said Ruoslahti. “So by those criteria, we seem to be targeting the right places.”

Tirrell added:”We think that self-assembled micelles (of peptide amphiphiles) of the sort we have used in this work are the most versatile, flexible nanoparticles for delivering diagnostic and therapeutic biofunctionality in vivo. The ease with which small particles, with sufficiently long circulation times and carrying peptides that target and treat pathological tissue, can be constructed by self-assembly is an important advantage.”

Ruoslahti said that UCSB’s strength in the areas of materials, chemistry, and bioengineering facilitated this research. He noted that he and Tirrell have been close collaborators.

 

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The work was funded by a grant from the National Heart, Lung and Blood Institute of the National Institutes of Health.

In addition to Ruoslahti and Tirrell, the article, “Targeting Atherosclerosis Using Modular, Multifunctional Micelles,” was authored by David Peters of the Burnham Institute at UCSB and the Biomedical Sciences Graduate Group at UC San Diego; Mark Kastantin of UCSB’s Department of Chemical Engineering; Venkata Ramana Kotamraju of the Burnham Institute at UCSB; Priya P. Karmali of the Cancer Research Center, Burnham Institute for Medical Research in La Jolla; and Kunal Gujraty of the Burnham Institute at UCSB.

March 17, 2009

Did life arrive from space?

Looks like this research from NASA lends a lot of credence to the idea life on Earth arrived via rocks from space. Very interesting.

The release fresh from the inbox:

NASA Researchers Find Clues to a Secret of Life

GREENBELT, Md., March 17 /PRNewswire-USNewswire/ — NASA scientists analyzing the dust of meteorites have discovered new clues to a long-standing mystery about how life works on its most basic, molecular level.

(Logo: http://www.newscom.com/cgi-bin/prnh/20081007/38461LOGO)

“We found more support for the idea that biological molecules, like amino acids, created in space and brought to Earth by meteorite impacts help explain why life is left-handed,” said Dr. Daniel Glavin of NASA’s Goddard Space Flight Center in Greenbelt, Md. “By that I mean why all known life uses only left-handed versions of amino acids to build proteins.” Glavin is lead author of a paper on this research appearing in the Proceedings of the National Academy of Sciences March 16.

Proteins are the workhorse molecules of life, used in everything from structures like hair to enzymes, the catalysts that speed up or regulate chemical reactions. Just as the 26 letters of the alphabet are arranged in limitless combinations to make words, life uses 20 different amino acids in a huge variety of arrangements to build millions of different proteins. Amino acid molecules can be built in two ways that are mirror images of each other, like your hands. Although life based on right-handed amino acids would presumably work fine, “you can’t mix them,” says Dr. Jason Dworkin of NASA Goddard, co-author of the study. “If you do, life turns to something resembling scrambled eggs — it’s a mess. Since life doesn’t work with a mixture of left-handed and right-handed amino acids, the mystery is: how did life decide — what made life choose left-handed amino acids over right-handed ones?”

Over the last four years, the team carefully analyzed samples of meteorites with an abundance of carbon, called carbonaceous chondrites. The researchers looked for the amino acid isovaline and discovered that three types of carbonaceous meteorites had more of the left-handed version than the right-handed variety — as much as a record 18 percent more in the often-studied Murchison meteorite. “Finding more left-handed isovaline in a variety of meteorites supports the theory that amino acids brought to the early Earth by asteroids and comets contributed to the origin of only left-handed based protein life on Earth,” said Glavin.

All amino acids can switch from left-handed to right, or the reverse, by chemical reactions energized with radiation or temperature, according to the team. The scientists looked for isovaline because it has the ability to preserve its handedness for billions of years, and it is extremely rarely used by life, so its presence in meteorites is unlikely to be from contamination by terrestrial life. “The meteorites we studied are from before Earth formed, over 4.5 billion years ago,” said Glavin. “We believe the same process that created extra left-handed isovaline would have created more left-handed versions of the other amino acids found in these meteorites, but the bias toward left-handed versions has been mostly erased after all this time.”

The team’s discovery validates and extends the research first reported a decade ago by Drs. John Cronin and Sandra Pizzarello of Arizona State University, who were first to discover excess isovaline in the Murchison meteorite, believed to be a piece of an asteroid. “We used a different technique to find the excess, and discovered it for the first time in the Orgueil meteorite, which belongs to another meteorite group believed to be from an extinct comet,” said Glavin.

The team also found a pattern to the excess. Different types of meteorites had different amounts of water, as determined by the clays and water-bearing minerals found in the meteorites. The team discovered meteorites with more water also had greater amounts of left-handed isovaline. “This gives us a hint that the creation of extra left-handed amino acids had something to do with alteration by water,” said Dworkin. “Since there are many ways to make extra left-handed amino acids, this discovery considerably narrows down the search.”

If the bias toward left-handedness originated in space, it makes the search for extraterrestrial life in our solar system more difficult, while also making its origin a bit more likely, according to the team. “If we find life anywhere else in our solar system, it will probably be microscopic, since microbes can survive in extreme environments,” said Dworkin. “One of the biggest problems in determining if microscopic life is truly extra-terrestrial is making sure the sample wasn’t contaminated by microbes brought from Earth. If we find the life is based on right-handed amino acids, then we know for sure it isn’t from Earth. However, if the bias toward left-handed amino acids began in space, it likely extends across the solar system, so any life we may find on Mars, for example, will also be left-handed. On the other hand, if there is a mechanism to choose handedness before life emerges, it is one less problem prebiotic chemistry has to solve before making life. If it was solved for Earth, it probably has been solved for the other places in our solar system where the recipe for life might exist, such as beneath the surface of Mars, or in potential oceans under the icy crust of Europa and Enceladus, or on Titan.”

The research was funded by the NASA Astrobiology Institute, the NASA Cosmochemistry program, and the NASA Astrobiology: Exobiology, and Evolutionary Biology program. For an image, refer to:

http://www.nasa.gov/centers/goddard/news/topstory/2009/left_hand_life.html

Photo:  http://www.newscom.com/cgi-bin/prnh/20081007/38461LOGO
AP Archive:  http://photoarchive.ap.org/
PRN Photo Desk photodesk@prnewswire.com
Source: NASA
   

Web Site:  http://www.nasa.gov/

February 12, 2009

February 2009 media tips from Oak Ridge National Laboratory

The release:

February 2009 Story Tips

(Story Tips Archive)

Story ideas from the Department of Energy’s Oak Ridge National Laboratory. To arrange for an interview with a researcher, please contact the Communications and External Relations staff member identified at the end of each tip.

MICROSCOPY—-STEM in liquid . . . . . .

Researchers at ORNL and Vanderbilt University have unveiled a new technique for imaging whole cells in liquid using a scanning transmission electron microscope. Electron microscopy is the most important tool for imaging objects at the nano-scale–the size of molecules and objects in cells. But electron microscopy requires a high vacuum, which has prevented imaging of samples in liquid, such as biological cells.” The new technique – liquid STEM – uses a micro-fluidic device with electron transparent windows to enable the imaging of cells in liquid. A team led by Niels de Jonge imaged individual molecules in a cell, with significantly improved resolution and speed compared with existing imaging methods. “Liquid STEM has the potential to become a versatile tool for imaging cellular processes on the nanometer scale,” said de Jonge. “It will potentially be of great relevance for the development of molecular probes and for the understanding of the interaction of viruses with cells.” The work was recently described in the on-line Proceedings of the National Academy of Sciences.

BIOLOGY—-Time-saving tool . . . . . .

Scientists studying human health, agriculture and the environment have a powerful new tool to help them better understand microbial processes and how they relate to ecosystems. The GeoChip consolidates into one analysis something that using traditional methods would require dozens of tests and take possibly years to complete, according to co-developer Chris Schadt of ORNL’s Biosciences Division. This lab on a chip features more than 24,000 gene probes that target more than 150 functional gene groups involved in biochemical, ecological and environmental processes. The GeoChip is especially useful for bioremediation of sediments and soils, determining the role of microbes in soil and learning how microbial processes are connected to ecosystem responses to human-induced environmental changes such as temperature, moisture and carbon dioxide. This research was funded by the Department of Energy’s Office of Biological and Environmental Research.

 

CYBERSPACE—-Thwarting threats . . . . . .

Colonies of cyber robots with unique missions can in near real time detect network intruders on computers that support U.S. infrastructure. These “cybots” created for an ORNL software program called UNTAME (Ubiquitous Network Transient Autonomous Mission Entities) may be especially useful for helping government agencies deter, defend, protect against and defeat cyber-attacks. “What scares us the most isn’t what we can see, but rather what we can’t see,” said Joe Trien of the lab’s Computational Sciences & Engineering Division. “A coordinated cyber attack could disrupt one or more of U.S. critical infrastructures, and these attacks can reach across the world at the speed of light.” Trien led a team of researchers that developed UNTAME.

 

COMPUTING—-First petascale projects . . . . . .

The National Center for Computational Sciences at Oak Ridge National Laboratory has granted early access to a number of projects to test Jaguar, which has peak performance of 1.6 petaflops and is the most powerful computer in the world for open science. The “Petascale Early Science” period will run approximately 6 months and consist initially of 20 projects, said NCCS Director of Science Doug Kothe. The early phase period seeks to deliver high-impact science results and advancements; harden the system for production; and embrace a broad user community to use the system, Kothe said. Proposals include: modeling to better understand climate change; energy storage and battery technology; cellulose conversion to ethanol; combustion research for more efficient automobile engines; and high-temperature superconductors for more efficient transmission of electricity. Fusion, nuclear energy, materials science, nuclear physics, astrophysics, and carbon sequestration also will be explored. “These early simulations on Jaguar will also help us harden the system for a broader collection of projects later in the year,” said Kothe.

January 21, 2009

Stretchable electronics news

Stretchable, flexible, electronics are a key component of wearable electronics, amongst many other applications. Any news on this front is always welcome.

The release:

University of Miami engineer designs stretchable electronics with a twist

The new mechanical design accommodates extreme bending and straining without reduction in electronic performance

IMAGE: This picture shows an optical image of a freely deformed stretchable array of complementary metal-oxide semiconductors inverters.

Click here for more information. 

CORAL GABLES, FL (January 21, 2008)- Jizhou Song, a professor in the University of Miami College of Engineering and his collaborators Professor John Rogers, at the University of Illinois and Professor Yonggang Huang, at Northwestern University have developed a new design for stretchable electronics that can be wrapped around complex shapes, without a reduction in electronic function.

The new mechanical design strategy is based on semiconductor nanomaterials that can offer high stretchability (e.g., 140%) and large twistability such as corkscrew twists with tight pitch (e.g., 90o in 1cm). Potential uses for the new design include electronic devices for eye cameras, smart surgical gloves, body parts, airplane wings, back planes for liquid crystal displays and biomedical devises.

“Our design is of great interest because the requirements for complex shapes that can function during stretching, compression, bending, twisting and other types of extreme mechanical deformation are impossible to satisfy with conventional technology,” said Song.

The secret of the design is in the silicon (Si) islands on which the active devices or circuits are fabricated. The islands form a chemically bonded, pre-strained elastomeric substrate. Releasing the pre-strain causes the metal interconnects of the circuits to buckle and form arc-shaped structures, which accommodate the deformation and make the semiconductor materials much more stretchable, without inducing significant changes in their electrical properties. The design is called noncoplanar mesh design.

The study is featured in the cover of the December issue of the Proceedings of the National Academy of Sciences (PNAS) and was selected for the special section of the journal called “In this issue.” The work is titled “Materials and Noncoplanar Mesh Designs for Integrated Circuits with Linear Elastic Responses to Extreme Mechanical Deformations”. The study describes a design system that can be stretched or compressed to high levels of strain, in any direction or combination of directions, with electronic properties that are independent of such strain, even in extreme arrangements. These types of systems might enable new applications not possible with current methods.

 

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November 20, 2008

Twisting electronics

One step closer to wearables.

The release:

Researchers make new electronics — with a twist

They’ve made electronics that can bend. They’ve made electronics that can stretch.

And now, they’ve reached the ultimate goal — electronics that can be subjected to any complex deformation, including twisting.

Yonggang Huang, Joseph Cummings Professor of Civil and Environmental Engineering and Mechanical Engineering at Northwestern University’s McCormick School of Engineering and Applied Science, and John Rogers, the Flory-Founder Chair Professor of Materials Science and Engineering at the University of Illinois at Urbana-Champaign, have improved their so-called “pop-up” technology to create circuits that can be twisted. Such electronics could be used in places where flat, unbending electronics would fail, like on the human body.

Their research is published online by the Proceedings of the National Academy of Sciences (PNAS).

Electronic components historically have been flat and unbendable because silicon, the principal component of all electronics, is brittle and inflexible. Any significant bending or stretching renders an electronic device useless.

Huang and Rogers developed a method to fabricate stretchable electronics that increases the stretching range (as much as 140 percent) and allows the user to subject circuits to extreme twisting. This emerging technology promises new flexible sensors, transmitters, new photovoltaic and microfluidic devices, and other applications for medical and athletic use.

The partnership — where Huang focuses on theory, and Rogers focuses on experiments — has been fruitful for the past several years. Back in 2005, the pair developed a one-dimensional, stretchable form of single-crystal silicon that could be stretched in one direction without altering its electrical properties; the results were published by the journal Science in 2006. Earlier this year they made stretchable integrated circuits, work also published in Science.

Next, the researchers developed a new kind of technology that allowed circuits to be placed on a curved surface. That technology used an array of circuit elements approximately 100 micrometers square that were connected by metal “pop-up bridges.”

The circuit elements were so small that when placed on a curved surface, they didn’t bend — similar to how buildings don’t bend on the curved Earth. The system worked because these elements were connected by metal wires that popped up when bent or stretched. The research was the cover article in Nature in early August.

In the research reported in PNAS, Huang and Rogers took their pop-up bridges and made them into an “S” shape, which, in addition to bending and stretching, have enough give that they can be twisted as well.

“For a lot of applications related to the human body — like placing a sensor on the body — an electronic device needs not only to bend and stretch but also to twist,” said Huang. “So we improved our pop-up technology to accommodate this. Now it can accommodate any deformation.”

Huang and Rogers now are focusing their research on another important application of this technology: solar panels. The pair published a cover article in Nature Materials this month describing a new process of creating very thin silicon solar cells that can be combined in flexible and transparent arrays.

 

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October 14, 2008

Writing protein nanoarrays

Nanotechnology news from Northwestern University.

The release:

Researchers write protein nanoarrays using a fountain pen and electric fields

EVANSTON, Ill. — Nanotechnology offers unique opportunities to advance the life sciences by facilitating the delivery, manipulation and observation of biological materials with unprecedented resolution. The ability to pattern nanoscale arrays of biological material assists studies of genomics, proteomics and cell adhesion, and may be applied to achieve increased sensitivity in drug screening and disease detection, even when sample volumes are severely limited.

Unfortunately, most tools capable of patterning with such tiny resolution were developed for the silicon microelectronics industry and cannot be used for soft and relatively sensitive biomaterials such as DNA and proteins.

Now a team of researchers at Northwestern University has demonstrated the ability to rapidly write nanoscale protein arrays using a tool they call the nanofountain probe (NFP).

“The NFP works much like a fountain pen, only on a much smaller scale, and in this case, the ink is the protein solution,” said Horacio Espinosa, head of the research team and professor of mechanical engineering in the McCormick School of Engineering and Applied Science at Northwestern.

The results, which will be published online the week of Oct. 13 in the Proceedings of the National Academy of Sciences (PNAS), include demonstrations of sub-100-nanometer protein dots and sub-200-nanometer line arrays written using the NFP at rates as high as 80 microns/second.

Each nanofountain probe chip has a set of ink reservoirs that hold the solution to be patterned. Like a fountain pen, the ink is transported to sharp writing probes through a series of microchannels and deposited on the substrate in liquid form.

“This is important for a number of reasons,” said Owen Loh, a graduate student at Northwestern who co-authored the paper with fellow student Andrea Ho. “By maintaining the sensitive proteins in a liquid buffer, their biological function is less likely to be affected. This also means we can write for extended periods over large areas without replenishing the ink.”

Earlier demonstrations of the NFP by the Northwestern team included directly writing organic and inorganic materials on a number of different substrates. These included suspensions of gold nanoparticles, thiols and DNA patterned on metallic- and silicon-based substrates.

In the case of protein deposition, the team found that by applying an electrical field between the nanofountain probe and substrate, they could control the transport of protein to the substrate. Without the use of electric fields, protein deposition was relatively slow and sporadic. However, with proper electrical bias, protein dot and line arrays could be deposited at extremely high rates.

“The use of electric fields allows an additional degree of control,” Espinosa said. “We were able to create dot and line arrays with a combination of speed and resolution not possible using other techniques.”

Positively charged proteins can be maintained inside the fountain probe by applying a negative potential to the NFP reservoirs with respect to a substrate. Reversing the applied potential then allows protein molecules to be deposited at a desired site.

To maximize the patterning resolution and efficiency, the team relied on computational models of the deposition process. “By modeling the ink flow within the probe tip, we were able to get a sense of what conditions would yield optimal patterns,” says Jee Rim, a postdoctoral researcher at Northwestern.

Espinosa collaborated closely with Neelesh Patankar, associate professor of mechanical engineering at Northwestern, and Punit Kohli, assistant professor of chemistry and biochemistry at Southern Illinois University, Carbondale.

“We are very excited by these results,” said Espinosa. “This technique is very broadly applicable, and we are pursuing it on a number of fronts.” These include single-cell biological studies and direct-write fabrication of large-scale arrays of nanoelectrical and nanoelectromechanical devices.

“The fact that we can batch fabricate large arrays of these fountain probes means we can directly write large numbers of features in parallel,” added Espinosa. “The demonstration of rapid protein deposition rates further supports our efforts in producing a large-scale nanomanufacturing tool.”

 

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The paper in the Proceedings of the National Academy of Sciences was authored by Loh, Ho, Rim, Patankar, Kohli and Espinosa.