Nerve cells grow on nanocellulose

Over a period of two years the research group has been trying to get human nerve cells to grow on nanocellulose.
“This has been a great challenge,” says Paul Gatenholm, Professor of Biopolymer Technology at Chalmers.? Until recently the cells were dying after a while, since we weren’t able to get them to adhere to the scaffold. But after many experiments we discovered a method to get them to attach to the scaffold by making it more positively charged. Now we have a stable method for cultivating nerve cells on nanocellulose.”
When the nerve cells finally attached to the scaffold they began to develop and generate contacts with one another, so-called synapses. A neural network of hundreds of cells was produced. The researchers can now use electrical impulses and chemical signal substances to generate nerve impulses, that spread through the network in much the same way as they do in the brain. They can also study how nerve cells react with other molecules, such as pharmaceuticals.
The researchers are trying to develop ?artificial brains”, which may open entirely new possibilities in brain research and health care, and eventually may lead to the development of biocomputers. Initially the group wants to investigate destruction of synapses between nerve cells, which is one of the earliest signs of Alzheimer’s disease. For example, they would like to cultivate nerve cells and study how cells react to the patients' spinal fluid.
In the future this method may be useful for testing various pharmaceutical candidates that could slow down the destruction of synapses.  In addition, it could provide a better alternative to experiments on animals within the field of brain research in general.
The ability to cultivate nerve cells on nanocellulose is an important step ahead since there are many advantages to the material.
?Pores can be created in nanocellulose, which allows nerve cells to grow in a three-dimensional matrix. This makes it extra comfortable for the cells and creates a realistic cultivation environment that is more like a real brain compared with a three-dimensional cell cultivation well,” says Paul Gatenholm.
Paul Gatenholm says that there are a number of new biomedical applications for nanocellulose. He is currently also leading other projects that use the material, for example a project where researchers are using nanocellulose to develop cartilage to create artificial outer ears. His research group has previously developed artificial blood vessels made of nanocellulose, which are being evaluated in pre-clinical studies.
Research on new application areas for nanocellulose is of major strategic significance for Sweden. Several projects are financed by the Knut and Alice Wallenberg Foundation and being conducted in collaboration between Chalmers and KTH within the Wallenberg Wood Science Center, WWSC.
The results will be presented at the American Chemical Society Meeting in San Diego, 25 March.

Provided by Chalmer's University of Technology

Fuel cells show potential

Fuel cells are an efficient, low carbon energy technology that could enable hydrogen fuel to replace the petrol and diesel we currently use to power our cars and other vehicles. However, the commercial uptake of fuel cell technologies has been hampered by high costs, a lack of specialised refuelling infrastructure and the limited durability of the fuel cells themselves.

One problem with PEM fuel cell durability is corrosion. This is particularly severe when the fuel cell is turned on or off and is caused by changes in electrode potential at the cathode, associated with the movement of the air/fuel boundary as hydrogen flows into or out from the anode. With repeated start-up/shutdown of the fuel cell, corrosion of the high surface area carbon material on which the platinum catalyst is supported causes a gradual decrease in available catalyst surface area and consequently a decrease in performance.

In NPL research explained in Electrochemistry Communications, the novel reference electrodes were used to measure the variation in electrode potential across the active area of a 50cm2 fuel cell supplied by Johnson Matthey. What makes the new reference electrodes special is the way that they connect to the fuel cell. Conventional reference electrodes are connected at the sides of the cell, meaning that they can only really measure what's going on around the edges, but the NPL reference electrode connects through holes drilled into the end plates, allowing a measurement of potential to be made at numerous points along the cell anode or cathode.

The electrodes are numbered with respect to the flow of hydrogen through the cell and measurements are taken at each point during operation. The movement of the air/fuel boundary through the cell can be detected by spikes in electrode potential and this can be mapped from the measurements taken by the electrodes. From this data, researchers can determine where and when corrosion is most likely to take place and investigate ways to reduce it.

NPL's Gareth Hinds, who led the project, said: "We are confident that this technique can be successfully applied to a wide range of fuel cell performance and durability issues, enhancing fundamental understanding of the underlying mechanisms and facilitating significant improvements in fuel cell design."

This provides fuel cell researchers and manufacturers with a powerful new diagnostic tool in the drive towards improved fuel cell performance and durability, which is critical for commercialisation of this energy technology.

This research was funded through the National Measurement System.

More information: In situ mapping of electrode potential in a PEM fuel cell, Electrochemistry Communications 17, 26-29.

Provided by National Physical Laboratory

Researchers create more efficient hydrogen fuel cells

 Hydrogen fuel cells, like those found in some "green" vehicles, have a lot of promise as an alternative fuel source, but making them practical on a large scale requires them to be more efficient and cost effective.

A research team from the University of Central Florida may have found a way around both hurdles.

The majority of hydrogen fuel cells use catalysts made of a rare and expensive metal -- platinum. There are few alternatives because most elements can't endure the fuel cell's highly acidic solvents present in the reaction that converts hydrogen's chemical energy into electrical power. Only four elements can resist the corrosive process -- platinum, iridium, gold and palladium. The first two are rare and expensive, which makes them impractical for large-scale use. The other two don't do well with the chemical reaction.

UCF Professor Sergey Stolbov and postdoctoral research associate Marisol Alcántara Ortigoza focused on making gold and palladium better suited for the reaction.

They created a sandwich-like structure that layers cheaper and more abundant elements with gold and palladium and other elements to make it more effective.

The outer monoatomic layer (the top of the sandwich) is either palladium or gold. Below it is a layer that works to enhance the energy conversion rate but also acts to protect the catalyst from the acidic environment. These two layers reside on the bottom slice of the sandwich -- an inexpensive substrate (tungsten), which also plays a role in the stability of the catalyst.

"We are very encouraged by our first attempts that suggest that we can create two cost-effective and highly active palladium- and gold-based catalysts -for hydrogen fuel cells, a clean and renewable energy source," Stolbov said.

Stolbov's work was recently published in The Journal of Physical Chemistry Letters.

By creating these structures, more energy is converted, and because the more expensive and rare metals are not used, the cost could be significantly less.

Stolbov said experiments are needed to test their predictions, but he says the approach is quite reliable. He's already working with a group within the U.S. Department of Energy to determine whether the results can be duplicated and have potential for large-scale application.

If a way could be found to make hydrogen fuel cells practical and cost effective, vehicles that run on gasoline and contribute to the destruction of the ozone layer could become a thing of the past.

Story Source:

The above story is reprinted from materials provided by University of Central Florida.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Sergey Stolbov, Marisol Alcántara Ortigoza. Rational Design of Competitive Electrocatalysts for Hydrogen Fuel Cells. The Journal of Physical Chemistry Letters, 2012; 3 (4): 463 DOI: 10.1021/jz201551e

Nanopore: the Oxford story

The announcement caught many by surprise, with the prospect of shrinking today’s bulky DNA sequencers into tiny devices that could decode the building blocks of life in hours (even seconds) instead of days, being widely reported in the media.

The blogosphere was abuzz with the exciting possibilities such machines open up.

Yet perhaps it shouldn’t have come as such a surprise: the firm’s success is built on nearly a decade of basic research at Oxford University’s Department of Chemistry.

Professor Hagan Bayley moved to Oxford in October 2003 having already done considerable research into how tiny pores in a protein might be used to detect the molecules passing through them, work he continued to develop in his Oxford lab.

In 2005, with the backing of IP Group and the help of Isis Innovation, Hagan founded Oxford Nanopore to commercialize his ideas.

"We were looking at sensing a wide range of molecules, but it was work we did at Oxford which showed, for the first time, that our nanopores could identify all four bases of DNA," Hagan explains.

"After that it made sense to shift the firm’s development into the area of DNA sequencing, a move which provided an impetus for many others to follow."

Conventional sequencing requires DNA samples to be amplified (which can introduce errors), cut to the right length, attached to a bead or surface and given a fluorescent tag which has to be read with expensive imaging equipment.

The pioneering approach developed by Hagan and his team was to eliminate tags and enable individual DNA bases to be snipped off a strand one by one and then fired through a nanopore. Each base disrupts an electric current passed across the nanopore by a different amount so the DNA base ‘letter’ (A, C, G or T) can be read.

"We found a modified pore that could clearly distinguish between the different bases," Hagan tells me, "but the big prize was strand sequencing – being able to pull a whole strand of DNA through a pore and read out the bases one at a time from that. It was work done at Oxford that first showed that this was possible."

Despite his role as the firm’s founder, a board member, and long-time scientific adviser, Hagan didn’t become its CEO; "my interest was always in the basic research" he says.

Instead, he continued to work with his team on the scientific challenges of understanding nanopores and what they can do, publishing papers that were useful to both the spinout and others interested in the potential of this emerging technology.

Yet the relationship remained a close one: former members of Hagan’s group would go on to play a significant role in the firm’s development as it grew from a small start-up to a company now employing 120 people.

Drawing on the basic research, Oxford Nanopore has been working hard for the last few years on creating the electronic hardware and software necessary to turn the nanopore concept into viable commercial devices. Its new MinION and GridION sequencers have already been hailed as ‘game-changing’ products on the road to cheaper, faster, more flexible DNA sequencing but this could be just the start, Hagan suggests: "we could see a high-throughput chip reading signals from hundreds of thousands of nanopores simultaneously, this could be very important for large-scale sequencing."

After a decade of working in this area Hagan believes it is now time for him to move on and find new avenues of research.

He believes that most new commercial exploitation opportunities come from basic research, and instead of research councils and universities trying to plan ‘pathways’ to new products and services: "the best way to do initial research is to find good motivated scientists, give them funding and time, and leave them alone."

Hagan tells me: "we need to make it simple for academics to form a company, don’t make them have to take a year out from their academic work or quit their university job to get things going." The support he received from Isis Innovation and others around the University indeed made spinning out a firm ‘relatively easy’. 

His message to funders and universities is that it’s how you treat your researchers that counts; support them and, in time, everyone will reap the rewards.

Provided by Oxford University (news : web)

Another piece of the ion pump puzzle

V-ATPases consist of a so-called ‘V complex’, which transfers energy derived from ATP hydrolysis into rotational motion, thereby promoting ion transport through to the membrane-bound V0 complex. These two complexes are joined by three ‘stalks’, including a central stalk composed of subunits named D and F, although this segment of the protein is poorly characterized. “The structure of this central axis of V-ATPase has not been obtained,” says Takeshi Murata of the RIKEN Systems and Structural Biology Center in Yokohama, “and we believe such structural studies are very important to understand this protein’s precise mechanism.”

Murata and colleagues recently succeeded in obtaining high-resolution structural information about the DF complex of V-ATPase obtained from the bacteria Enterococcus hirae1. By comparing this structural information against an equivalent segment from F-ATPase, which synthesizes rather than hydrolyzes ATP, the researchers were able to identify functional domains that may be specifically required by V-ATPases.

They determined that the E. hirae D subunit is composed of a pair of long helical structures coiled around each other, with a short hairpin-shaped loop at one end. According to Murata, the discovery of this latter structure was unexpected. “This short beta-hairpin region is a unique structure, although the rest of the D structure is very similar to that of other rotary complexes such as F-ATPase and flagellar motors,” he says. This segment does not appear to be essential for V-ATPase assembly, but ATP processing efficiency was reduced when the researchers deleted this hairpin from the subunits.

In contrast, the E. hirae F subunit assumed a more compact structure, relatively similar to its A- and F-ATPase counterparts; the researchers determined that it specifically associates with the middle portion of the D subunit’s coiled helical segment, an interaction that depends heavily on a particular helix within the F subunit. 

Although untangling this structure represents a major step forward, this complex must also be understood as part of a far larger entity (Fig. 1). Murata and colleagues have already begun tackling this. “We recently succeeded at solving the structure of V1-ATPase with a resolution of 2.1 Angstroms,” says Murata, “and we are now preparing this manuscript for publication.”

More information: Saijo, S.,et al. Crystal structure of the central axis DF complex of the prokaryotic V-ATPase. Proceedings of the National Academy of Sciences USA 108, 19955–19960 (2011).

Provided by RIKEN (news : web)

New technology to aid crystallization prediction

The software, which has been developed at the University of Leeds, in collaboration with the Cambridge Crystallographic Data Centre (CCDC) is called Visual HABIT. It offers a significant improvement on existing predictive resources and will enable companies to adopt a more 'bottom up' approach to the design of products or formulated products in the pharmaceutical, agrochemical and fuel sectors.

The software helps companies predict crystal properties in different chemical environments, something which will reduce extensive early-stage laboratory research, bringing down development costs and helping to bring new products to market more efficiently. It also has the ability to show what happens to crystalline particles under different processing conditions.

"Being able to see how crystal properties change within different processing environments is really important, because often companies have put in years of work before they even get to this stage," says Professor Kevin Roberts who is leading the research. "As chemical engineers, we have to make sure that the quality of a product remains the same in a manufacturing environment as in the laboratory. It's a bit like ensuring a meal cooked for 1000 guests is exactly the same quality as the same meal cooked for just four people. Our aim is to ensure that in scaling up different processes, none of the quality is lost. Our technology will help overcome some of the obstacles that slow down the research and development processes in these sectors."

Visual HABIT will also be a valuable resource for the nuclear sector, where crystallisation during long term storage can create difficulties in the effective processing of waste.

"We're excited about our software because we can see enormous benefits to all the sectors we're working with," says Professor Roberts. "If companies already know – at the beginning of the development process - how different chemical formulations are going to behave under a range of conditions, it'll speed up development times, cut costs and may result in superior products."

The Leeds research group, called Synthonic Engineering, is working with CCDC and five industry partners from across the pharmaceutical, agrochemical, fuel, nuclear and instrumentation sectors to ensure effective translation of the new technology. It aims to commercialise the technology within 12 months.

"We are delighted to be part of this collaborative venture" says Colin Groom, Executive Director of the CCDC. "In the past we have focussed on how knowledge and understanding derived from Cambridge Structural Database can be used in the discovery and development of drugs. This partnership allows us to explore the application of crystallographic and structural information to particle engineering. Our experience in software development will ensure practical and useful software tools are delivered in an exciting area that is new to us."

Provided by University of Leeds (news : web)

Glowing White: Solvent-free luminescent organic liquids for organic electronics

Current approaches to organic electronics mainly involve plastic film supports with conducting paths and components made of organic molecules inexpensively printed or glued on. Organic electronics are interesting as potential “disposable electronics” for applications like electronic price tags. Even more intriguing are devices that cannot be produced with standard electronics, such as flexible films with integrated circuits for use as novel flat-panel displays or “electronic paper”. A third area of interest involves applications such as photovoltaics that are dependent on economical mass production in order to be profitable.

The development of large components like displays requires organic coatings that emit white light and are inexpensive to produce. Previous gel- or solvent-based liquid “dyes” are easy to apply, but are often not colorfast or are barely luminescent after drying. For solids, on the other hand, processing is often too complex.

A team led by Takashi Nakanishi at the National Institute for Materials Science in Tsukaba (Japan) has taken a different approach: they use uncharged organic substances that are luminescent liquids at room temperature and require no solvent. The electronically active parts of the molecules consist of linear chains of carbon atoms linked by ?-conjugated double bonds. This means that electrons can move freely over a large portion of the molecule. The core is shielded by low-viscosity organic side chains that ensure that the core areas do not interact with each other and that the substance remains liquid.

The researchers were able to prepare a liquid that fluoresces blue under UV light. They then dissolved green- and orange-emitting dyes in this solvent-free liquid. This results in a durable, stable white-emitting paste whose glow can be adjusted from a “cool” bluish white to a “warm” yellowish white by changing the ratio of the dyes. It is possible to use this ink directly in a roller-ball pen for writing, or to apply it with a brush on a wide variety of surfaces. Application to a commercially available UV-LED allowed the researchers to produce white light-emitting diodes.

More information: Takashi Nakanishi, Solvent-Free Luminescent Organic Liquids, Angewandte Chemie International Edition, http://dx.doi.org/10.1002/anie.201108853

Provided by Wiley (news : web)

Researchers create more efficient hydrogen fuel cells

A research team from the University of Central Florida may have found a way around both hurdles.

The majority of hydrogen fuel cells use catalysts made of a rare and expensive metal – platinum. There are few alternatives because most elements can't endure the fuel cell's highly acidic solvents present in the reaction that converts hydrogen's chemical energy into electrical power. Only four elements can resist the corrosive process – platinum, iridium, gold and palladium. The first two are rare and expensive, which makes them impractical for large-scale use. The other two don't do well with the chemical reaction.

UCF Professor Sergey Stolbov and postdoctoral research associate Marisol Alcántara Ortigoza focused on making gold and palladium better suited for the reaction.

They created a sandwich-like structure that layers cheaper and more abundant elements with gold and palladium and other elements to make it more effective.

The outer monoatomic layer (the top of the sandwich) is either palladium or gold. Below it is a layer that works to enhance the energy conversion rate but also acts to protect the catalyst from the acidic environment. These two layers reside on the bottom slice of the sandwich -- an inexpensive substrate (tungsten), which also plays a role in the stability of the catalyst.

"We are very encouraged by our first attempts that suggest that we can create two cost-effective and highly active palladium- and gold-based catalysts –for hydrogen fuel cells, a clean and renewable energy source," Stolbov said.

Stolbov's work was recently published in the Journal of Physical Chemistry Letters.

By creating these structures, more energy is converted, and because the more expensive and rare metals are not used, the cost could be significantly less.

Stolbov said experiments are needed to test their predictions, but he says the approach is quite reliable. He's already working with a group within the U.S. Department of Energy to determine whether the results can be duplicated and have potential for large-scale application.

If a way could be found to make hydrogen fuel cells practical and cost effective, vehicles that run on gasoline and contribute to the destruction of the ozone layer could become a thing of the past.

Stolbov joined UCF's physics department in 2006. Before that he was a research assistant professor at Kansas State University. He earned multiple degrees in physics from Rostov State University in Russia and was a Postdoctoral Fellow at the Carnegie Institution of Washington, D.C. He is a frequent international speaker and has written dozens of articles on physics.

Provided by University of Central Florida (news : web)

Soft ray looks to save lives by developing rapid, low-cost system for detection of bacteria in blood platelets

Johnson, a University of Wyoming professor of physics since 1981, is venturing from the classroom to the boardroom with his biotechnology company SoftRay Inc., where he has created a lab instrument that can be used in hospitals and health clinics to detect bacteria in blood platelets or fungus in blood much earlier than current methodologies allow. And he is receiving assistance and expertise from the Wyoming Technology Business Center to make it happen.

"The WTBC has helped me develop a business plan. I've received feedback from venture capitalists and developed presentations to give to venture capitalists," says Johnson, who is currently in the pre-venture stage of his business idea. "They've helped me connect with a lot of people in the business community."

The WTBC is a statewide business development program (under the UW Office of Research and Economic Development) that is developing a technology business incubator and an outreach program focused on early-stage, high-growth companies. The 30,000-square-foot facility, which opened in 2006, offers laboratory, office and shared-conference room space for client companies as well as a state-of-the-art data center.

Johnson has created a technology he calls FountainFlow cytometry, which is used for measuring microorganisms in food, water and human blood. The platform technology can be used to detect environmental or drinking water contamination, fungus in the blood and bacteria in blood platelets -- and more quickly than current detection methods, Johnson says.

Platelets are the cells in human blood which cause blood to coagulate upon exposure to air. Platelets are used for transfusions for hospital patients who have undergone trauma or bled out; or for people who are immune-compromised, meaning their bodies cannot naturally produce platelets on their own.

Johnson says his technology -- which he began working on approximately six years ago because he wanted to make a significant societal impact -- can detect fungal infection in blood within a few hours compared to the current methodology, such as culturing, which takes 1-3 days to diagnose a form of fungus. That can be the difference between life and death for a patient who has gone into septic shock. A person can die from septic shock within 1-24 hours while current diagnosis typically takes 48-72 hours, Johnson says.

"A person's survival rate depends critically on quick diagnosis and treatment," Johnson says. "With our current FountainFlow platform technology, we will be able to make a diagnosis within 1-2 hours. And the physician will be able to use the appropriate drug regimen to save the person's life."

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In his technology, Johnson says a fluid, such as blood or water, is mixed with chemicals. It is then pumped through the hoses of the instrument. The fluid is illuminated, using light from an LED. A dye is added to the fluid, which allows Johnson to pinpoint the microorganisms he's specifically interested in detecting. When the microorganisms are illuminated with the ultra-bright LED light, the microorganisms glow. A camera, which is part of the instrument, captures video frames of that fluid flow. A computer can analyze those frames to count the number of glowing particles in the images. It then determines the number of particles per volume in the fluid flow. This process allows the physician to determine the level of infection.

"Camera technology and LED technology have both become cheaper and more powerful," Johnson says. "I've managed to ride both of those waves to develop an instrument that can conduct cell detection."

Johnson currently is conducting his research with Poudre Valley Hospital in Fort Collins and Bonfils Blood Center in Denver. Poudre Valley Hospital is a 241-bed regional medical center which serves northern Colorado, southern Wyoming and western Nebraska. Bonfils operates six community donor centers; serves nearly 200 health care facilities in Colorado and beyond; and collects nearly 154,000 units of blood annually, according to its website.

While Johnson conducts his research at his laboratory in UW's Physical Sciences Building and at Bonfils -- with the aid of National Institutes of Health (NIH) grants -- he stressed that the WTBC and its facilities have been invaluable to his efforts.

"There is a lot of commercialization with something as complicated as this device. It requires meeting with (people in the) business and scientific fields," Johnson says. "I've been able to meet with people very good at dye development, and those that have to work with blood and blood platelets. I'm constantly getting feedback. They (WTBC) really care about the success of their clients."

He adds, "The great thing about the WTBC is we have a group of people intimately familiar with high-tech business development. It's really great to have someone identify problems. Before, I felt isolated. They (WTBC) have a lot of experience."

Johnson said he has lived and learned with a previous Laramie-based business venture, First Magnitude Corp., he started. First Magnitude marketed electronic, high-sensitive cameras used for research. While that company proved profitable, Johnson admitted to some business mistakes.

"We were attracting the high end of the market, but we didn't have the patents" for the technology, Johnson recalls. "If you don't have the patents, you get taken over rapidly by the big boys."

When he started SoftRay, Johnson shuttered First Magnitude Corp. And he vowed to learn from that experience.

While UW owns the patent on Johnson's technology, Johnson has an exclusive license on the patent, which means he owns the rights to market the technology.

Johnson says he is still mulling whether he would want to manufacture the technology himself or provide a license to a large corporation with production and manufacturing facilities already in place.

"I would like to be a Laramie-based company for the foreseeable future. The bio-detection industry is growing and is in excess of $30 billion annually," Johnson says. "I'd like to be a major player in the bio-detection industry."

In addition to the health care industry, Johnson sees other potential market applications -- including detection of contamination in food and water products -- for his technology.

"We're interested in licensing technology," he says. "If someone would want to use it for bottled water, that would be huge. The sky's the limit."

Provided by University of Wyoming

Ultracold experiments heat up quantum research

University of Chicago physicists have experimentally demonstrated for the first time that atoms chilled to temperatures near absolute zero may behave like seemingly unrelated natural systems of vastly different scales, offering potential insights into links between the atomic realm and deep questions of cosmology.

This ultracold state, called "quantum criticality," hints at similarities between such diverse phenomena as the gravitational dynamics of black holes or the exotic conditions that prevailed at the birth of the universe, said Cheng Chin, associate professor in physics at UChicago. The results could even point to ways of simulating cosmological phenomena of the early universe by studying systems of atoms in states of quantum criticality.

"Quantum criticality is the entry point for us to make connections between our observations and other systems in nature," said Chin, whose team is the first to observe quantum criticality in ultracold atoms in optical lattices, a regular array of cells formed by multiple laser beams that capture and localize individual atoms.

UChicago graduate student Xibo Zhang and two co-authors published their observations online Feb. 16 in Science Express and in the March 2 issue of Science.

Quantum criticality emerges only in the vicinity of a quantum phase transition. In the physics of everyday life, rather mundane phase transitions occur when, for example, water freezes into ice in response to a drop in temperature. The far more elusive and exotic quantum phase transitions occur only at ultracold temperatures under the influence of magnetism, pressure or other factors.

"This is a very important step in having a complete test of the theory of quantum criticality in a system that you can characterize and measure extremely well," said Harvard University physics professor Subir Sachdev about the UChicago study.

Physicists have extensively investigated quantum criticality in crystals, superconductors and magnetic materials, especially as it pertains to the motions of electrons. "Those efforts are impeded by the fact that we can't go in and really look at what every electron is doing and all the various properties at will," Sachdev said.

Sachdev's theoretical work has revealed a deep mathematical connection between how subatomic particles behave near a quantum critical point and the gravitational dynamics of black holes. A few years hence, offshoots of the Chicago experiments could provide a testing ground for such ideas, he said.

There are two types of critical points, which separate one phase from another. The Chicago paper deals with the simpler of the two types, an important milestone to tackling the more complex version, Sachdev said. "I imagine that's going to happen in the next year or two and that's what we're all looking forward to now," he said.

Critical Experiments

Other teams at UChicago and elsewhere have observed quantum criticality under completely different experimental conditions. In 2010, for example, a team led by Thomas Rosenbaum, the John T. Wilson Distinguished Service Professor in Physics at UChicago, observed quantum criticality in a sample of pure chromium when it was subjected to ultrahigh pressures.

Zhang, who will receive his doctorate this month, invested nearly two and a half years of work in the latest findings from Chin's laboratory. Co-authoring the study with Zhang and Chin were Chen-Lung Hung, PhD'11, now a postdoctoral scientist at the California Institute of Technology, and UChicago postdoctoral scientist Shih-Kuang Tung.

In their tabletop experiments, the Chicago scientists use sets of crossed laser beams to trap and cool up to 20,000 cesium atoms in a horizontal plane contained within an eight-inch cylindrical vacuum chamber. The process transforms the atoms from a hot gas to a superfluid, an exotic form of matter that exists only at temperatures hundreds of degrees below zero.

"The whole experiment takes six to seven seconds and we can repeat the experiment again and again," Zhang said.

The experimental apparatus includes a CCD camera sensitive enough to image the distribution of atoms in a state of quantum criticality. The CCD camera records the intensity of laser light as it enters that vacuum chamber containing thousands of specially configured ultracold atoms.

"What we record on the camera is essentially a shadow cast by the atoms," Chin explained.

The UChicago scientists first looked for signs of quantum criticality in experiments performed at ultracold temperatures from 30 to 12 nano-Kelvin, but failed to see convincing evidence. Last year they were able to push the temperatures down to 5.8 nano-Kelvin, just billionths of a degree above absolute zero (minus 459 degrees Fahrenehit). "It turns out that you need to go below 10 nano-Kelvin in order to see this phenomenon in our system," Chin said.

Chin's team has been especially interested in the possibility of using ultracold atoms to simulate the evolution of the early universe. This ambition stems from the quantum simulation concept that Nobel laureate Richard Feynman proposed in 1981. Feynman maintained that if scientists understand one quantum system well enough, they might be able to use it to simulate the operations of another quantum system that can be difficult to study directly.

For some, like Harvard's Sachdev, quantum criticality in ultracold atoms is worthy of study as a physical system in its own right. "I want to understand it for its own beautiful quantum properties rather than viewing it as a simulation of something else," he said.

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Story Source:

The above story is reprinted from materials provided by University of Chicago, via Newswise.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

X. Zhang, C.-L. Hung, S.-K. Tung, C. Chin. Observation of Quantum Criticality with Ultracold Atoms in Optical Lattices. Science, 2012; 335 (6072): 1070 DOI: 10.1126/science.1217990

Diamond-based materials brighten the future of electronics

 While diamonds may be a girl's best friend, they're also well-loved by scientists working to enhance the performance of electronic devices.

Two new studies performed at the U.S. Department of Energy's Argonne National Laboratory have revealed a new pathway for materials scientists to use previously unexplored properties of nanocrystalline-diamond thin films. While the properties of diamond thin films are relatively well-understood, the new discovery could dramatically improve the performance of certain types of integrated circuits by reducing their "thermal budget."

For decades, engineers have sought to build more efficient electronic devices by reducing the size of their components. In the process of doing so, however, researchers have reached a "thermal bottleneck," said Argonne nanoscientist Anirudha Sumant.

In a thermal bottleneck, the excess heat generated in the device causes undesirable effects that affect its performance. "Unless we come-up with innovative ways to suck the heat off of our electronics, we are pretty much stuck with this bottleneck," Sumant explained.

The unusually attractive thermal properties of diamond thin films have led scientists to suggest using this material as a heat sink that could be integrated with a number of different semiconducting materials. However, the deposition temperatures for the diamond films typically exceed 800 degrees Celsius -- roughly 1500 degrees Fahrenheit, which limits the feasibility of this approach.

"The name of the game is to produce diamond films at the lowest possible temperature. If I can grow the films at 400 degrees, it makes it possible for me to integrate this material with a whole range of other semiconductor materials," Sumant said.

By using a new technique that altered the deposition process of the diamond films, Sumant and his colleagues at Argonne's Center for Nanoscale Materials were able to both reduce the temperature to close to 400 degrees Celsius and to tune the thermal properties of the diamond films by controlling their grain size. This permitted the eventual combination of the diamond with two other important materials: graphene and gallium nitride.

According to Sumant, diamond has much better heat conduction properties than silicon or silicon oxide, which were traditionally used for fabrication of graphene devices. As a result of better heat removal, graphene devices fabricated on diamond can sustain much higher current densities.

In the other study, Sumant used the same technology to combine diamond thin films with gallium nitride, which is used extensively in high-power light emitting devices (LED). After depositing a 300 nm-thick diamond film on a gallium nitride substrate, Sumant and his colleagues noticed a considerable improvement in the thermal performance. Because a difference within an integrated circuit of just a few degrees can cause a noticeable change in performance, he called this result "remarkable."

"The common link between these experiments is that we're finding new ways of dissipating heat more effectively while using less energy, which is the key," Sumant said. "These processes are crucial for industry as they look for ways to overcome conventional limits on semiconducting circuits and pursue the next generation of electronics."

The results of the two studies were reported in Nano Letters and Advanced Functional Materials. Both of these studies were carried out in collaboration with Prof. Alexander Balandin at the University of California-Riverside and his graduate students Jie Yu, Guanxiong Liu and Dr. Vivek Goyal, a recent Ph.D. graduate.

Funding for the research conducted at the Center for Nanoscale Materials was provided by the Basic Energy Sciences program of the U.S. Department of Energy's Office of Science.

Story Source:

The above story is reprinted from materials provided by DOE/Argonne National Laboratory. The original article was written by Jared Sagoff.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal References:

Vivek Goyal, Anirudha V. Sumant, Desalegne Teweldebrhan, Alexander A. Balandin. Direct Low-Temperature Integration of Nanocrystalline Diamond with GaN Substrates for Improved Thermal Management of High-Power Electronics. Advanced Functional Materials, 2012; DOI: 10.1002/adfm.201102786Jie Yu, Guanxiong Liu, Anirudha V. Sumant, Vivek Goyal, Alexander A. Balandin. Graphene-on-Diamond Devices with Increased Current-Carrying Capacity: Carbon sp2-on-sp3Technology. Nano Letters, 2012; : 120215161807006 DOI: 10.1021/nl204545q

Planting the seeds for heart-healthier fries and other foods

In the article, C&EN Senior Business Editor Melody M. Bomgardner explains that roughly 22 billion pounds of vegetable oils are used for food making in the U.S. each year. So-called partially hydrogenated vegetable oils, which can extend products' shelf-lives, were widely used in preparing restaurant foods such as french fries, as well as snack foods and baked goods since the early 1900s. But mounting evidence in the 1990s showed that these oils are not healthful because of the trans fats that are formed in their production. Trans fats increase the risk of heart disease by raising levels of "bad" cholesterol and lowering levels of "good" cholesterol.

By the time the Food and Drug Administration began requiring food manufacturers to list trans fats on their labels in 2006, Dow and DuPont were already exploring alternatives. The companies plan to launch new seeds that promise oilseed crops with healthier fat content in 2013. Dow's Plenish soybean was genetically engineered, while DuPont's Nexera canola and sunflower were produced through plant breeding. Both companies' products have high amounts of oleic acid, which has been shown to be much more heart-healthy than partially hydrogenated oils. The first target market for these "high-oleic" oils is fried foods, where they can be reused more often than current oils, resulting in a 40 percent cost savings to the food industry. Companies are still working on similar products that could replace shortenings used for baked goods.

More information: Replacing Trans Fat - http://cen.acs.org/articles/90/i11/Replacing-Trans-Fat.html

Provided by American Chemical Society (news : web)

Two-in-one imaging agents

Such magnetoluminescent imaging agents consist of three components: a luminescent probe, a contrast agent, and a linker to combine the two. The use of lanthanide complexes as luminescent probes has the advantage of affording long luminescence lifetimes, which makes the system suitable for use in time-gated luminescence spectroscopy. Enhancing the absorption of the lanthanide terbium with a phenanthridine antenna provided an ideal luminescent probe. Magnetic iron oxide nanoparticles, known for their superior longitudinal and especially transverse relaxivities, were employed as the contrast agent, and a polyethylene glycol (PEG) linker was used to coat the luminescent probes onto the magnetic nanoparticles.

In addition to a precise luminescent probe and a contrast agent with excellent relaxivities, these systems are not cytotoxic, as, for example, systems held together by silica matrices. Moreover, the PEG coating is not as thick and is more water-permeable, which results in considerably improved cellular uptake and higher relaxivity.

More information: Valérie C. Pierre, Magnetoluminescent Agents for Dual MRI and Time-Gated Fluorescence Imaging, European Journal of Inorganic Chemistry, http://dx.doi.org/ … ic.201200045

 

New gecko insights inspire even stronger adhesives

But researchers at the University of Massachusetts Amherst have made the connection.

First they showed  the previously unappreciated role of geckos' tendons and bones in the little lizards' ability to climb up walls without slipping. Then they used that knowledge -- plus a large helping of human ingenuity -- to create an adhesive device that can hold the television securely on a wall.

"Our 'Geckskin' device is about the size of an index card and can hold a maximum force of about 700 pounds while adhering to a smooth surface such as glass," said Alfred Crosby, associate professor of polymer science and engineering at the University of Massachusetts Amherst.

To produce it, Crosby added, "We focused on the properties and attributes of the gecko: high capacity, easy release, reliability, and the ability to stick to a variety of surfaces."

"This is definitely an important contribution," said Metin Sitti, professor of mechanical engineering at Carnegie Mellon University and an expert on small-scale locomotion and manipulation, who did not participate in the project.

Crosby carried out the research with his doctoral candidate Michael Bartlett and biology professor Duncan Irschick, with support from the Pentagon's Defense Advanced Projects Research Agency.

Scientists have long recognized that so-called van der Waals forces, which produce weak electrical attraction among molecules, cause adhesion between tiny hairs in geckos' toes, known as setae, and vertical surfaces on which the geckos climb.

However, efforts to apply that process on a large scale have had limited success. Scotch tape gains its stickiness through the van der Waals forces.

"But you can't make the forces stronger," Crosby said. "People have tried to produce artificial setae," Irschick added. "But they don't scale up effectively."

To develop a different approach, the UMass team studied the large-scale structure of geckos' feet.

Expanding on research by University of Calgary biologist Anthony Russell, the team discovered how tendons, bones, and skin work together to produce the easily reversible adhesion that causes a gecko's feet to stick to a wall briefly and then release from it as the tiny lizard moves up, down, or sideways on the wall. The process works in large part because of the role of the tendons. In most creatures, tendons connect bones to muscles.

"But in geckos' feet, uniquely, the tendons stretch from bone into skin," Irschick explained.

The group used that knowledge as the basis of an adhesive system stronger than any relying on van der Waals forces.

"We wanted something that would cover a large area and would become increasingly stiff," Crosby recalled. "But those demands are contradictory."

Scotch tape, for example, covers a large area, but is soft and thus unable to hold significant weight. The geckos' anatomy suggested that the team could overcome the contradiction by using a specially treated fabric. A fabric can be both soft and stiff. A tablecloth, for instance, can drape over a table and conform to the shape of anything underneath it while remaining stiff if you try to pull it. For their Geckskin, the researchers mimicked the anatomy of geckos' feet.

"We took a fabric, put a bit of rubber around it, and sewed another piece of fabric -- the 'tendon' -- into that 'skin'," Crosby explained.

Since the fabric is stiff and the rubber soft, the combination yields a stiff but flexible system that drapes over a large surface area, permitting maximum contact and adhesion.

Geckskin's strength does not apply in all directions. While it is almost impossible to move it along any surface on which it is mounted, Crosby said, "a gentle peel from one edge allows it to be effortlessly removed from the surface on command."

It can be removed and stuck onto another surface as often as needed without leaving any residue or losing adhesive strength.

The team has used a variety of ingredients for the rubber component. In particular polydimethylsiloxane, a component of silly putty, holds the promise, in combination with fabric, of developing an inexpensive, strong, and durable dry adhesive.

The researchers also tried a variety of fabrics.

"Those with the greatest load capacity use the fibers such as Kevlar and fiber-based fabrics that are most stiff," Crosby said.

According to Crosby, Geckskin stacks up well against current commercial adhesives.

"The force per area is definitely higher than all the pressure-sensitive adhesives," Crosby said. "The combination of high force and user release is not there in available adhesive systems. And unlike Velcro, Geckskin doesn't need a matching surface."

The team, which reported its advance in the journal Advanced Materials, is now discussing possible commercialization of the technology. 

Source: Inside Science News Service (news : web)

Study finds how bacteria resist a 'Trojan horse' antibiotic

The study appears in the Proceedings of the National Academy of Sciences.

Bacteria often engage in chemical warfare with one another, and many antibiotics used in medicine are modeled on the weapons they produce. But microbes also must protect themselves from their own toxins. The defenses they employ for protection can be acquired by other species, leading to antibiotic resistance.

The researchers focused on an enzyme, known as MccF, that they knew could disable a potent "Trojan horse" antibiotic that sneaks into cells disguised as a tasty protein meal. The bacterial antibiotic, called microcin C7 (McC7) is similar to a class of drugs used to treat bacterial infections of the skin.

"How Trojan horse antibiotics work is that the antibiotic portion is coupled to something that's fairly innocuous – in this case it's a peptide," said University of Illinois biochemistry professor Satish Nair, who led the study. "So susceptible bacteria see this peptide, think of it as food and internalize it."

The meal comes at a price, however: Once the bacterial enzymes chew up the amino acid disguise, the liberated antibiotic is free to attack a key component of protein synthesis in the bacterium, Nair said.

"That is why the organisms that make this thing have to protect themselves," he said.

In previous studies, researchers had found the genes that protect some bacteria from this class of antibiotic toxins, but they didn't know how they worked. These genes code for peptidases, which normally chew up proteins (polypeptides) and lack the ability to recognize anything else.

Before the new study, "it wasn't clear how a peptidase could destroy an antibiotic," Nair said.

To get a fuller picture of the structure of the peptidase, Illinois graduate student Vinayak Agarwal crystallized MccF while it was bound to other molecules, including the antibiotic. An analysis of the structure and its interaction with the antibiotic revealed that MccF looked a lot like other enzymes in its family, but with a twist – or, rather, a loop. Somehow MccF has picked up an additional loop of amino acids that it uses to recognize the antibiotic, rendering it ineffective.

"Now we know that specific amino acid residues in this loop are responsible for making this from a normal housekeeping gene into something that's capable of degrading this class of antibiotics," Nair said.

With this information, researchers – and eventually, doctors and other clinicians – will be able to scan the genomes of disease-causing bacteria to find out which ones have genes with the antibiotic-resistance loop in them, Nair said. "If we know what type of bacteria are causing an infection we know what kind of antibiotic to give and what kind not to give," he said.

Nair is also an affiliate of the Center for Biophysics and Computational Biology, the department of chemistry and of the Institute for Genomic Biology at Illinois. The research team included scientists from the Russian Academy of Sciences and Rutgers University.

Provided by University of Illinois at Urbana-Champaign (news : web)

Nano rescues skin: Shrimp shell nanotech for wound healing and anti-aging face cream

 Nanoparticles containing chitosan have been shown to have effective antimicrobial activity against Staphylococcus saprophyticus and Escherichia coli. The materials could be used as a protective wound-healing material to avoid opportunistic infection as well as working to facilitate wound healing.

Chitosan is a natural, non-toxic and biodegradable, polysaccharide readily obtained from chitin, the main component of the shells of shrimp, lobster and the beak of the octopus and squid. Its antimicrobial activity is well known and has been exploited in dentistry to prevent caries and as preservative applications in food packaging. It has even been tested as an additive for antimicrobial textiles used in clothing for healthcare and other workers.

Now, Mihaela Leonida of Fairleigh Dickinson University, in Teaneck, New Jersey and colleagues writing in the International Journal of Nano and Biomaterials describe how they have prepared nanoparticles of chitosan that could have potential in preventing infection in wounds as well as enhancing the wound-healing process itself by stimulating skin cell growth.

The team made their chitosan nanoparticles (CNP) using an ionic gelation process with sodium tripolyphosphate. This process involves the formation of bonds between polymers strands, a so-called cross-linking process. Conducted in these conditions it precludes the need for complex preparative chemistry or toxic solvents. CNP can also be made in the presence of copper and silver ions, known antimicrobial agents. The researchers' preliminary tests show the composite materials to have enhanced activity against two representative types of bacteria.

Understanding the mechanism of inhibition of bacteria by these particles may lead to the preparation of more effective antibacterial agents. The team has also demonstrated that the CNP have skin regenerative properties in tests on skin cell fibroblasts and keratinocytes, in the laboratory, which might even have implications for anti-aging skin care products.

Story Source:

The above story is reprinted from materials provided by Inderscience Publishers, via EurekAlert!, a service of AAAS.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Mihaela D. Leonida; Sudeep Banjade; Thong Vo; Gloria Anderle; Gerhard J. Haas; Neena Philips. Nanocomposite materials with antimicrobial activity based on chitosan. International Journal of Nano and Biomaterials, 2012 DOI: 10.1504/IJNBM.2011.045885

Molecular graphene heralds new era of 'designer electrons'

Researchers from Stanford University and the U.S. Department of Energy's SLAC National Accelerator Laboratory have created the first-ever system of "designer electrons" -- exotic variants of ordinary electrons with tunable properties that may ultimately lead to new types of materials and devices.

"The behavior of electrons in materials is at the heart of essentially all of today's technologies," said Hari Manoharan, associate professor of physics at Stanford and a member of SLAC's Stanford Institute for Materials and Energy Sciences, who led the research. "We're now able to tune the fundamental properties of electrons so they behave in ways rarely seen in ordinary materials."

Their first examples, recently reported in Nature, were hand-crafted, honeycomb-shaped structures inspired by graphene, a pure form of carbon that has been widely heralded for its potential in future electronics. Initially, the electrons in this structure had graphene-like properties; for example, unlike ordinary electrons, they had no mass and traveled as if they were moving at the speed of light in a vacuum. But researchers were then able to tune these electrons in ways that are difficult to do in real graphene.

To make the structure, which Manoharan calls molecular graphene, the scientists use a scanning tunneling microscope to place individual carbon monoxide molecules on a perfectly smooth copper surface. The carbon monoxide repels the free-flowing electrons on the copper surface and forces them into a honeycomb pattern, where they behave like graphene electrons.

To tune the electrons' properties, the researchers repositioned the carbon monoxide molecules on the surface; this changed the symmetry of the electron flow. In some configurations, electrons acted as if they had been exposed to a magnetic or electric field. In others, researchers were able to finely tune the density of electrons on the surface by introducing defects or impurities. By writing complex patterns that mimicked changes in carbon-carbon bond lengths and strengths in graphene, the researchers were able to restore the electrons' mass in small, selected areas.

"One of the wildest things we did was to make the electrons think they are in a huge magnetic field when, in fact, no real field had been applied,"Manoharan said. Guided by the theory developed by co-author Francisco Guinea of Spain, the Stanford team calculated the positions where carbon atoms in graphene should be to make its electrons believe they were being exposed to magnetic fields ranging from zero to 60 Tesla, more than 30 percent higher than the strongest continuous magnetic field ever achieved on Earth. The researchers then moved carbon monoxide molecules to steer the electrons into precisely those positions, and the electrons responded by behaving exactly as predicted -- as if they had been exposed to a real field.

"Our new approach is a powerful new test bed for physics," Manoharan said. "Molecular graphene is just the first in a series of possible designer structures. We expect that our research will ultimately identify new nanoscale materials with useful electronic properties."

Additional authors included Kenjiro K. Gomes, Warren Mar and Wonhee Ko of the Stanford Institute for Material and Energy Sciences. Francisco Guinea is a researcher at the Madrid Materials Science Institute. The research was supported by the U.S. Department of Energy's Office of Basic Energy Sciences, the National Science Foundation and the Spanish Ministry of Science & Innovation.

Story Source:

The above story is reprinted from materials provided by DOE/SLAC National Accelerator Laboratory.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Kenjiro K. Gomes, Warren Mar, Wonhee Ko, Francisco Guinea, Hari C. Manoharan. Designer Dirac fermions and topological phases in molecular graphene. Nature, 2012; 483 (7389): 306 DOI: 10.1038/nature10941

Killer silk: Making silk fibers that kill anthrax and other microbes in minutes

Rajesh R. Naik and colleagues explain that in adverse conditions, bacteria of the Bacillus species, which includes anthrax, become dormant spores, enclosing themselves in a tough coating. These spores can survive heat, radiation, antibiotics and harsh environmental conditions, and some have sprung back to life after 250 million years. Certain chemicals — most popular among which are oxidizing agents, including some chlorine compounds — can destroy bacterial spores, and they have been applied to fabrics like cotton, polyester, nylon and Kevlar. These treated fabrics are effective against many bacteria, but less so against spores. The researchers tried a similar coating on silk to see if it could perform better against these hardy microbes.

They developed a chlorinated form of silk, which involves soaking silk in a solution that includes a substance similar to household bleach and letting it dry. Silk treated for just an hour killed essentially all of the E. coli bacteria tested on it within 10 minutes and did similarly well against spores of a close anthrax relative used as a stand-in. "Given the potent bactericidal and sporicidal activity of the chlorinated silk fabrics prepared in this study, silk-Cl materials may find use in a variety of applications," the authors say. Other applications, they add, include purifying water in humanitarian relief efforts and in filters or to mitigate the effects of toxic substances.

More information: Sporicidal/Bactericidal Textiles via the Chlorination of Silk, ACS Appl. Mater. Interfaces, Article ASAP, DOI: 10.1021/am2018496

Abstract
Bacterial spores, such as those of the Bacillus genus, are extremely resilient, being able to germinate into metabolically active cells after withstanding harsh environmental conditions or aggressive chemical treatments. The toughness of the bacterial spore in combination with the use of spores, such as those of Bacillus anthracis, as a biological warfare agent necessitates the development of new antimicrobial textiles. In this work, a route to the production of fabrics that kill bacterial spores and cells within minutes of exposure is described. Utilizing this facile process, unmodified silk cloth is reacted with a diluted bleach solution, rinsed with water, and dried. The chlorination of silk was explored under basic (pH 11) and slightly acidic (pH 5) conditions. Chloramine-silk textiles prepared in acidified bleach solutions were found to have superior breaking strength and higher oxidative Cl contents than those prepared under caustic conditions. Silk cloth chlorinated for ?1 h at pH 5 was determined to induce >99.99996% reduction in the colony forming units of Escherichia coli, as well as Bacillus thuringiensis Al Hakam (B. anthracis simulant) spores and cells within 10 min of contact. The processing conditions presented for silk fabric in this study are highly expeditionary, allowing for the on-site production of protein-based antimicrobial materials from a variety of agriculturally produced feed-stocks.

Provided by American Chemical Society (news : web)

Straintronics: Engineers create piezoelectric graphene

 In what became known as the 'Scotch tape technique," researchers first extracted graphene with a piece of adhesive in 2004. Graphene is a single layer of carbon atoms arranged in a honeycomb, hexagonal pattern. It looks like chicken wire.

Graphene is a wonder material. It is one-hundred-times better at conducting electricity than silicon. It is stronger than diamond. And, at just one atom thick, it is so thin as to be essentially a two-dimensional material. Such promising physics have made graphene the most studied substance of the last decade, particularly in nanotechnology. In 2010, the researchers who first isolated it shared the Nobel Prize.

Yet, while graphene is many things, it is not piezoelectric. Piezoelectricity is the property of some materials to produce electric charge when bent, squeezed or twisted. Perhaps more importantly, piezoelectricity is reversible. When an electric field is applied, piezoelectric materials change shape, yielding a remarkable level of engineering control.

Piezoelectrics have found application in countless devices from watches, radios and ultrasound to the push-button starters on propane grills, but these uses all require relatively large, three-dimensional quantities of piezoelectric materials.

Now, in a paper published in the journal ACS Nano, two materials engineers at Stanford have described how they have engineered piezoelectrics into graphene, extending for the first time such fine physical control to the nanoscale.

Straintronics

"The physical deformations we can create are directly proportional to the electrical field applied and this represents a fundamentally new way to control electronics at the nanoscale," said Evan Reed, head of the Materials Computation and Theory Group at Stanford and senior author of the study. "This phenomenon brings new dimension to the concept of 'straintronics' for the way the electrical field strains -- or deforms -- the lattice of carbon, causing it to change shape in predictable ways."

"Piezoelectric graphene could provide an unparalleled degree of electrical, optical or mechanical control for applications ranging from touchscreens to nanoscale transistors," said Mitchell Ong, a post-doctoral scholar in Reed's lab and first author of the paper.

Using a sophisticated modeling application running on high-performance supercomputers, the engineers simulated the deposition of atoms on one side of a graphene lattice -- a process known as doping -- and measured the piezoelectric effect.

They modeled graphene doped with lithium, hydrogen, potassium and fluorine, as well as combinations of hydrogen and fluorine and lithium and fluorine on either side of the lattice. Doping just one side of the graphene, or doping both sides with different atoms, is key to the process as it breaks graphene's perfect physical symmetry, which otherwise cancels the piezoelectric effect.

The results surprised both engineers.

"We thought the piezoelectric effect would be present, but relatively small. Yet, we were able to achieve piezoelectric levels comparable to traditional three-dimensional materials," said Reed. "It was pretty significant."

Designer piezoelectricity

"We were further able to fine tune the effect by pattern doping the graphene -- selectively placing atoms in specific sections and not others," said Ong. "We call it designer piezoelectricity because it allows us to strategically control where, when and how much the graphene is deformed by an applied electrical field with promising implications for engineering."

While the results in creating piezoelectric graphene are encouraging, the researchers believe that their technique might further be used to engineer piezoelectricity in nanotubes and other nanomaterials with applications ranging from electronics, photonics, and energy harvesting to chemical sensing and high-frequency acoustics.

"We're already looking now at new piezoelectric devices based on other 2D and low-dimensional materials hoping they might open new and dramatic possibilities in nanotechnology," said Reed.

The Army High Performance Computing Research Center at Stanford University (http://me.stanford.edu/research/centers/ahpcrc/index.html) and the National Energy Research Scientific Computing Center (NERSC) at the Lawrence Berkeley National Laboratory supported this research.

Listen to Reed and Ong talk about their work with ACS Nano: http://www.stanford.edu/group/evanreed/media/ancac3-0212.mp3

Story Source:

The above story is reprinted from materials provided by Stanford School of Engineering. The original article was written by Andrew Myers, associate director of communications for the Stanford University School of Engineering.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Mitchell T. Ong, Evan J. Reed. Engineered Piezoelectricity in Graphene. ACS Nano, 2012; 6 (2): 1387 DOI: 10.1021/nn204198g

Novel U. of Colorado 3D super-resolution imaging technology to be developed by Boulder company

The technology was developed by CU-Boulder Professor Rafael Piestun of the electrical and computer engineering department. Super-resolution -- techniques to enhance the resolution of an imaging system beyond the limitations set by the diffraction of light -- is key to the development of next-generation microscopes and other optical instruments. The Double Helix optical technology combines 3D optics and a unique signal post-processing technique used for quality improvement in image processing.

The optical technology offers a major opportunity to provide multifunctional 3D super-resolution imaging capability to thousands of cellular, molecular biology and biophysics laboratories in the United States and around the world. The Double Helix technology platform is applicable to a variety of scientific, industrial and consumer applications, including microscopy, metrology and computational digital photography, said Piestun.

Piestun also is the director of Computational Optical Sensing and Imaging, a National Science Foundation-funded program for education and research training.

"We are looking forward to bringing this leading-edge technology to the market, initially in microscopy and later to more markets including metrology and digital optics, a stronghold of the Boulder entrepreneurial community," said Double Helix founding partner Leslie Kimerling.

"We are excited to see this company launch with our broad fundamental patents," said Ted Weverka, a licensing manager at the CU Technology Transfer Office. "The cost savings and superior technology will give Double Helix a strong lead."

Provided by University of Colorado at Boulder (news : web)

New microfluidic chip can generate microbubbles to break open cells for biochemical analysis

Currently there is a wide range of methods to disintegrate or lyse cell membranes and to release the biomolecules contained within. However, most of these methods can cause denaturation of proteins or interfere with subsequent assaying. Ow and co-workers explored the possibility of using ultrasound in microfluidics to lyse cells. They applied short bursts of ultrasound with periods of rest to prevent the proteins from overheating as a result of dissipation of mechanical energy.

When the rapid changes of pressure generated with ultrasound are applied to a liquid, small bubbles are formed which oscillate in size and generate a cyclic shear stress. These rapidly oscillating bubbles generate a mini shockwave when they implode, which can be strong enough to cause the cell membrane to rupture. The researchers generated microbubbles in the meandering microfluidic channel by introducing a gas via a separate inlet to generate a gas–liquid interface and subsequently applying ultrasound to the system.

As a proof of principle, the researchers tested the performance of their microfluidic device on genetically engineered bacteria and yeast that express the green fluorescent protein. The researchers found that the bacteria are completely disintegrated after only 0.4 seconds of ultrasound exposure (see image). The concentration of DNA released from yeast cells reached a plateau after only one second exposure (which contained six bursts of ultrasound each of 0.154 seconds), indicating that most cells are successfully lysed. Importantly the temperature of the sample was shown not to rise above 3.3 °C. “The large surface to volume ratio of the microfluidic environment means that the small amount of heat that is generated rapidly diffuses away,” says Ow.

The researchers have proposed many ideas for applications. “In collaboration with another institute, we are developing a rapid and sensitive label-free optical method for on-chip detection of bioanalytes from lysed cells,” says Ow. “We also want to modify the device to break more difficult-to-lyse endospores, and to develop a rapid on-chip detection device to counter the threats of bioterrorism.”

More information: Research article in Lab on a chip

Provided by Agency for Science, Technology and Research (A*STAR)

Butterfly molecule may aid quest for nuclear clean-up technology

 Scientists have produced a previously unseen uranium molecule, in a move that could improve clean-up of nuclear waste.

The distinctive butterfly-shaped compound is similar to radioactive molecules that scientists had proposed to be key components of nuclear waste.

However, these were thought too unstable to exist for long.

Researchers have shown the compound to be robust, which implies that molecules with a similar structure may be present in radioactive waste.

Better clean-up

University scientists, who carried out the study, say their findings suggest the molecule may play a role in forming clusters of radioactive material in waste.

These are difficult to separate during clean-up.

Improving treatment processes for nuclear waste, including targeting this type of molecule, could help the nuclear industry move towards cleaner power generation.

Ideally, all the radioactive materials from spent fuel can be recovered and made safe or used again.

This would reduce the amount of waste and curb risks to the environment.

Distinctive shape

The Edinburgh team worked in collaboration with scientists in the United States and Canada to verify the structure of the uranium compound.

They made the molecule by reacting a common uranium compound with a nitrogen and carbon-based material.

Scientists used chemical and mathematical analyses to confirm the structure of the molecule's distinctive butterfly shape.

The study, funded by the Engineering and Physical Sciences Research Council, the EaStCHEM partnership and the University of Edinburgh, was published in Nature Chemistry.

"We have made a molecule that, in theory, should not exist, because its bridge-shaped structure suggests it would quickly react with other chemicals. This discovery that this particular form of uranium is so stable could help optimise processes to recycle valuable radioactive materials and so help manage the UK's nuclear legacy," said Professor Polly Arnold of the School of Chemistry.

Story Source:

The above story is reprinted from materials provided by University of Edinburgh.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

Journal Reference:

Polly L. Arnold, Guy M. Jones, Samuel O. Odoh, Georg Schreckenbach, Nicola Magnani, Jason B. Love. Strongly coupled binuclear uranium–oxo complexes from uranyl oxo rearrangement and reductive silylation. Nature Chemistry, 2012; 4 (3): 221 DOI: 10.1038/nchem.1270

A new tool to reveal structure of proteins

For roughly a decade, a technique called solid state nuclear magnetic resonance (NMR) spectroscopy has allowed researchers to detect the arrangements of atoms in proteins that defy study by traditional laboratory tools such as X-ray crystallography. But translating solid state NMR data into an actual 3D protein structures has always been difficult.

In the current online edition of Nature Chemistry, Christopher Jaroniec, associate professor of chemistry at Ohio State University, and his colleagues describe a new solid state NMR method that uses paramagnetic tags to help visualize the shape of protein molecules.

"Structural information about biological molecules is critical to understanding their function," Jaroniec said. "Our new method promises to be a valuable addition to the NMR toolbox for rapidly determining the structures of protein systems which defy analysis with other techniques."

Such protein systems include amyloids, which are fibrous clusters of proteins found in diseased cells, and associated with the development of certain neurological diseases in humans.

"Although for the purposes of the paper we tested the method on a small model protein, the applications are actually quite general," Jaroniec added. "We expect that the method will work on many larger and more challenging proteins."

Protein molecules are made up of long chains of amino acids folded and wrapped around themselves, like tangled spaghetti. Every type of protein folds into its own unique pattern, and the pattern determines its function in the body. Understanding why a protein folds the way it does could give scientists clues on how to destroy a protein, or alter its function.

To test their method, the researchers chose a protein called GB1, a common protein found in Streptococcus bacteria. GB1 has been much studied by scientists, so the structure is already known. They engineered a form of the protein in which certain amino acids along the chain were replaced with a different amino acid – cysteine – and created the right chemical conditions for yet another tag – one containing an atom of copper – to stick to the cysteine. The amino acid-copper tags are known as "paramagnetic" molecules, and they significantly influence the signals emitted by the different protein atoms in the magnetic field of an NMR instrument.

The researchers were able to determine the locations of the protein atoms relative to the paramagnetic tags, and use this information to calculate the folded shape of the GB1 protein.

Provided by The Ohio State University (news : web)

Scientists discover a surprising new way that protons can move among molecules

Hydrogen bonds are found everywhere in chemistry and biology and are critical in DNA and RNA, where they bond the base pairs that encode genes and map protein structures. Recently a team of researchers using the Advanced Light Source (ALS) at the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) discovered to their surprise that in special cases protons can find ways to transfer even when hydrogen bonds are blocked. The team's results appear in Nature Chemistry.

Stacking the odd molecules

A group led by Musahid Ahmed, a senior scientists in Berkeley Lab's Chemical Sciences Division (CSD), has long collaborated with a theoretical research group at the University of Southern California (USC) headed by Anna Krylov. In recent work to understand how bases are bonded in staircase-like molecules like DNA and RNA, Krylov's group made computer models of paired, ring-shaped uracil molecules, and investigated what might happen to these doubled forms (dimers) when they were subjected to ionization – the removal of one or more electrons with resulting net positive charge.

Uracil is one of the four nucleobases of RNA, whose structure is similar to DNA except that, while both use the bases adenine, cytosine, and guanine, in DNA the fourth base is thymine and in RNA it's uracil. The USC group used a uracil dimer labeled 1,3-dimethyluracil – "a strange creature that doesn't necessarily exist in nature," says CSD's Amir Golan, who led the Berkeley Lab team at the ALS. The purpose of this strange creature, Golan says, is to block hydrogen bonding of the two identical monomers of the uracil dimer by attaching a methyl group to each, "because methyl groups are poison to hydrogen bonds."

The uracils could still bond in the vertical direction by means of pi bonds, which are perpendicular to the usual plane of bonding among the flat rings of uracil and other nucleobases. "Pi stacking" is important in the configuration of DNA and RNA, in protein folding, and in other chemical structures as well, and pi stacking was what interested the USC researchers. They brought their theoretical calculations to Berkeley Lab for experimental testing at the ALS's Chemical Dynamics beamline 9.0.2.

To examine how the molecules were bonded, Golan and his colleagues first created a gaseous molecular beam of real methylated uracil monomers and dimers, then ionized them with a beam of energetic ultraviolet light from the ALS synchrotron. The resulting species were weighed in a mass spectrometer to see how the uracil had responded to the extra boost of energy.

"Uracils could be joined by hydrogen bonds or by pi bonds, but these uracils had been methylated to block hydrogen bonds. So what we expected to see when we ionized them was that if they were bonded, they would have to be stacked on top of each other," Golan says. Instead of holding together by pi bonds, however, when ionized some uracil dimers had fallen apart into monomers that carried an extra proton.

Where the protons come from

"What we did not expect to see was proton transfer," Golan says. "Surprising as this was, we needed to find where the protons were coming from. The methyl groups consist of a single carbon atom and three hydrogen atoms, but methylated uracil has other hydrogens too. Still, the methyl groups were the natural suspects."

To test this hypothesis, the researchers invited colleagues from Berkeley Lab's Molecular Foundry to join the collaboration. They created methyl groups in which the hydrogen atoms – which like most hydrogen had single protons as their nuclei – were replaced by deuterium atoms, "heavy hydrogen" atoms with nuclei consisting of a proton and a neutron of virtually the same mass.

The molecular beam experiment was repeated at the ALS, and once again some of the methylated uracil dimers fell apart into monomers upon ionization. This time, however, the tell-tale monomers were not simply protonated, they were deuterated.

Says Golan, "By looking at the mass of the fragments we could see that instead of uracil plus one" – the mass of a single proton – "they were uracil plus two" – a proton and neutron, or deuteron. "This proved that indeed the transferred protons came from the methyl groups."

The experiment showed that proton transfer in this case followed a very different route from the usual process of hydrogen bonding. Here the transfer involved not just an attraction between molecular arrangements that were slightly positively charged and others that were slightly negatively charged, as in a hydrogen bond. Instead it required significant rearrangements of the two uracil dimer fragments, to allow protons of hydrogen atoms in the methyl group on one monomer to move closer to an oxygen atom in the other. Theoretical calculations of the new pathway were led by USC's Krylov and Ksenia Bravaya.

The moral of the story, says Golan, is that methyl groups do not always kill proton transfer. "Granted, this was a model system – what we did was ionize the uracil systems in the gas phase instead of in solution, as would be the case in a living organism," he says. "Nevertheless, we showed that proton transfer is possible without hydrogen-bonding networks. Which means there could be unsuspected pathways for proton transfer in RNA and DNA and other biological processes – especially those that involve pi-stacking – as well as in environmental chemistry and in purely chemical processes like catalysis."

The next step: a range of new experiments to directly map proton transfer rates and gain structural insight into the transfer mechanism, with the goal of visualizing these unexpected new pathways for proton transfer.

More information: "Ionization of dimethyluracil dimers leads to facile proton transfer in the absence of H-bonds," by Amir Golan, Ksenia B. Bravaya, Romas Kudirka, Oleg Kostko, Stephen R. Leone, Anna I. Krylov, and Musahid Ahmed, is published by Nature Chemistry and appears in advance online publication at http://www.nature. … m/index.html .

Provided by Lawrence Berkeley National Laboratory (news : web)

Cyborg snail produces electricity

But whereas the grapes and cockroaches could generate electricity for just days or weeks, Evgeny Katz, a professor of chemistry at Clarkson University in Potsdam, New York, and colleagues have shown that the snail can generate electricity for many months at a time. And in spite of the electrodes in their shells, the snails live long, healthy lives.

“The animals are quite fit - they eat, drink and crawl,” Katz told Nature News. "We take care to keep them alive and happy.”

Although a snail's tissues and organs are bathed in blood, or haemolymph, it takes time to regenerate its glucose levels, which means snails don't generate very large amounts of power. For the first few minutes, the researchers could extract 7.45 microwatts, but this power decreased to just 0.16 microwatts during long-term, continuous extraction. The main cause of this decay comes from the local depletion of glucose at the electrode surface. Still, the snail's eating and resting could sufficiently regenerate its overall glucose levels, allowing it to “recharge” and produce sustainable electrical power.

These snails - as well as other potential electrified creatures such as worms and insects - could be useful for powering low-power devices, such as sensors and wireless transmitters. The US Department of Defense is funding cyborg research in the hopes of creating bugs that can gather information about their environment while crawling around. Researchers are also investigating medical applications, in which a patient's implantable biofuel cell could use his or her own blood glucose to power medical devices such as pacemakers.

In the future, the researchers at Clarkson University plan to electrify lobsters in the same way as the snails, with the hopes that the larger animals' metabolism could provide more power.

More information: Lenka Halámková, et al. "Implanted Biofuel Cell Operating in a Living Snail." Journal of the American Chemical Society. DOI: 10.1021/ja211714w

Abstract
Implantable biofuel cells have been suggested as sustainable micropower sources operating in living organisms, but such bioelectronic systems are still exotic and very challenging to design. Very few examples of abiotic and enzyme-based biofuel cells operating in animals in vivo have been reported. Implantation of biocatalytic electrodes and extraction of electrical power from small living creatures is even more difficult and has not been achieved to date. Here we report on the first implanted biofuel cell continuously operating in a snail and producing electrical power over a long period of time using physiologically produced glucose as a fuel. The “electrified” snail, being a biotechnological living “device”, was able to regenerate glucose consumed by biocatalytic electrodes, upon appropriate feeding and relaxing, and then produce a new “portion” of electrical energy. The snail with the implanted biofuel cell will be able to operate in a natural environment, producing sustainable electrical micropower for activating various bioelectronic devices.

 

Researcher sees marine nutraceuticals as growth industry

Lee, a professor emeritus of food sciences, describes nutraceuticals as a cross between pharmaceuticals and nutrition, something that "provides health benefits above and beyond traditional nutrients. The nutraceutical market is dominated by terrestrial sources, like cranberries that provide antioxidants. Marine nutraceuticals are something new, and now it is getting a lot more attention," he said.

The URI food scientist says that the "big ticket item" among marine nutraceuticals is fish oil, which contains omega 3 fatty acids that provide cardiovascular disease risk reductions, immune function improvements, brain health, and reductions in inflammation from rheumatoid arthritis. Most fish oil products are derived from anchovies and sardines caught in the waters off Peru and Chile.

In Rhode Island, seaweed could play a role in the nutraceutical industry, as some varieties are a source of compounds beneficial to human and animal health. One species of seaweed called rockweed (Ascopyllum nodosum) that Lee is studying is abundant along the coast of New England and is already being used as an agricultural fertilizer and as an additive to animal feeds. Lee says it also has bioactive components that are useful in managing weight, lowering cholesterol and slowing the digestion of sugars and carbohydrates.

Lee's former postdoctoral student, Emmanouil Apostolidis, is studying the seasonal variation of these beneficial properties to determine the best time of year to harvest the seaweed and examining its stability to determine how long it can remain on the shelf before it's potency declines."

Lee is also working with squid processors in North Kingstown and Point Judith in the development of nutraceuticals from the by-products of squid processing. A global pet food company has already been in touch with Lee about using squid by-products in its products to improve animal health.

In addition, Lee is collaborating with the Rhode Island Commercial Fisheries Research Foundation and local scallop fishermen on research to find a beneficial use for the by-products of scallop harvesting.

"We only consume the adductor muscle of scallops, and the rest – 70 percent of it – is thrown overboard," said Lee. "We're investigating its potential. One of my assistants, Bouhee Kang, is working on this project. It may stimulate digestion enzyme activity and help people who have difficulty digesting oily foods. There is a big market for digestion relief supplements, especially in Asia."

Lee believes that Rhode Island could benefit from more research into marine nutraceuticals.

"In the past, most of the funding for this kind of research in the U.S. has gone to the development of drugs from marine organisms. I hope the funding will come soon for nutraceuticals as well," said Lee, who recently organized an international symposium on global trends in marine nutraceuticals. "It has great potential, and it could give a big boost to the Rhode Island economy."

Provided by University of Rhode Island (news : web)