Silk Moth's Antenna Inspires New Nanotech Tool With Applications in Alzheimer's Research

A paper on the work is newly published online inNature Nanotechnology. This project is headed by Michael Mayer, an associate professor in the U-M departments of Biomedical Engineering and Chemical Engineering. Also collaborating are Jerry Yang, an associate professor at the University of California, San Diego and Jiali Li, an associate professor at the University of Arkansas.

Nanopores -- essentially holes drilled in a silicon chip -- are miniscule measurement devices that enable the study of single molecules or proteins. Even today's best nanopores clog easily, so the technology hasn't been widely adopted in the lab. Improved versions are expected to be major boons for faster, cheaper DNA sequencing and protein analysis.

The team engineered an oily coating that traps and smoothly transports molecules of interest through nanopores. The coating also allows researchers to adjust the size of the pore with close-to-atomic precision.

"What this gives us is an improved tool to characterize biomolecules," Mayer said."It allows us to gain understanding about their size, charge, shape, concentration and the speed at which they assemble. This could help us possibly diagnose and understand what is going wrong in a category of neurodegenerative disease that includes Parkinson's, Huntington's and Alzheimer's."

Mayer's"fluid lipid bilayer" resembles a coating on the male silk moth's antenna that helps it smell nearby female moths. The coating catches pheromone molecules in the air and carries them through nanotunnels in the exoskeleton to nerve cells that send a message to the bug's brain.

"These pheromones are lipophilic. They like to bind to lipids, or fat-like materials. So they get trapped and concentrated on the surface of this lipid layer in the silk moth. The layer greases the movement of the pheromones to the place where they need to be. Our new coating serves the same purpose," Mayer said.

One of Mayer's main research tracks is to study proteins called amyloid-beta peptides that are thought to coagulate into fibers that affect the brain in Alzheimer's. He is interested in studying the size and shape of these fibers and how they form.

"Existing techniques don't allow you to monitor the process very well. We wanted to see the clumping of these peptides using nanopores, but every time we tried it, the pores clogged up," Mayer said."Then we made this coating, and now our idea works."

To use nanopores in experiments, researchers position the pore-pricked chip between two chambers of saltwater. They drop the molecules of interest into one of the chambers and send an electric current through the pore. As each molecule or protein passes through the pore, it changes the pore's electrical resistance. The amount of change observed tells the researchers valuable information about the molecule's size, electrical charge and shape.

Due to their small footprint and low power requirements, nanopores could also be used to detect biological warfare agents.

A research highlight on this work will appear in an upcoming edition of Nature. The paper is titled"Controlling protein translocation through nanopores with bio-inspired fluid walls."

This research is funded by the National Science Foundation, the National Institutes of Health, the Alzheimer's Disease Research Center, the Alzheimer's Association and the National Human Genome Research Institute. The university is pursuing patent protection for the intellectual property, and is seeking commercialization partners to help bring the technology to market.

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Floating Solar Panels: Solar Installations on Water

Developed by a Franco-Israeli partnership,* this innovative solar power technology introduces a new paradigm in energy production. Solar power plays a dominant role in the world-wide effort to reduce greenhouse gases, it is considered a clean energy and is an efficient source of electricity. Yet several obstacles have been undermining the expansion of this sector and many of its actors are looking for a new approach towards the markets.

A win-win Situation

Soon after the design phase was over, at the end of March 2010, the fabrication of a prototype began and the team is now aiming to launch the implementation phase in September 2011. The tests will take place at Cadarache, in the South East of France, the site having a privileged position on the French electric grid and being close to a local hydro-electric facility providing the water surface to be used for the installation of the system. It will operate on-site during a period of nine months, while assessing the system's performances and productivity through seasonal changes and various water levels. The research team members believe that by June 2012, they will have all the information required to allow the technology's entry on the market.

As even leading photovoltaic companies struggle to find land on which to install solar power plants, the project team identified the almost untouched potential of solar installations on water. The water basins, on which the plants could be built, are not natural reserves, tourists' resorts or open sea; rather they are industrial water basins already in use for other purposes. By that, it is assured that the new solar plants will not have a negative impact on natural landscapes."It's a win-win situation," declares Dr. Kassel,"since there are many water reservoirs with energy, industrial or agricultural uses that are open for energy production use."

After solving the question of space, the team also took on the problem of cost."It sounds magical to combine sun and water to produce electricity, but we also have to prove that it carries a financial logic for the long run," explains Dr. Kassel. The developers were able to reduce the costs linked to the implementation of the technology by two means. First they reduced the quantity of solar cells used thanks to a sun energy concentration system based on mirrors, while keeping steady the amount of power produced.

Made of modules

Secondly, the team used a creative cooling system using the water on which the solar panels are floating. Thanks to this efficient cooling method, the photovoltaic system can use silicon solar cells, which tend to experience problems linked to overheating and need to be cooled down in order to allow the system to work correctly, unlike standard type more expensive cells. The particular type of solar cell used also allows a higher efficiency than the standard ones, achieving both reliability and cost reduction.

Still for the purpose of making the technology efficient and ready to market, the system is designed in such way that on a solar platform it is possible to assemble as many identical modules as needed for the power rating desired. Each module produces a standard amount of 200 kiloWatt electricity, and more power can be achieved by simply adding more modules to the plant.

The team also worked on the environmental impact of the technology. It works in fact as a breathing surface through which oxygen can penetrate to the water. This feature ensures that sufficient oxygen will maintain the underwater life of plants and animals. Dr. Kassel adds:"One of the implementation phase's goals is to closely monitor the possible effects of this new technology on the environment with the help of specialists" and"a preliminary check shows no detrimental environmental impact on water quality, flora or fauna. Our choices of materials were always made with this concern in mind."

*The project results from a collaboration between Solaris Synergy from Israel and the EDF Group from France. EUREKA provided the supporting platform which allowed to enhance both companies' partnership. After receiving the"EUREKA label" the project, called AQUASUN, found also support from the Israeli Ministry of Industry, Trade and Labor.

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New Stretchable Solar Cells Will Power Artificial Electronic 'Super Skin'

Super skin, indeed.

"With artificial skin, we can basically incorporate any function we desire," said Bao, a professor of chemical engineering."That is why I call our skin 'super skin.' It is much more than what we think of as normal skin."

The foundation for the artificial skin is a flexible organic transistor, made with flexible polymers and carbon-based materials. To allow touch sensing, the transistor contains a thin, highly elastic rubber layer, molded into a grid of tiny inverted pyramids. When pressed, this layer changes thickness, which changes the current flow through the transistor. The sensors have from several hundred thousand to 25 million pyramids per square centimeter, corresponding to the desired level of sensitivity.

To sense a particular biological molecule, the surface of the transistor has to be coated with another molecule to which the first one will bind when it comes into contact. The coating layer only needs to be a nanometer or two thick.

"Depending on what kind of material we put on the sensors and how we modify the semiconducting material in the transistor, we can adjust the sensors to sense chemicals or biological material," she said.

Bao's team has successfully demonstrated the concept by detecting a certain kind of DNA. The researchers are now working on extending the technique to detect proteins, which could prove useful for medical diagnostics purposes.

"For any particular disease, there are usually one or more specific proteins associated with it -- called biomarkers -- that are akin to a 'smoking gun,' and detecting those protein biomarkers will allow us to diagnose the disease," Bao said.

The same approach would allow the sensors to detect chemicals, she said. By adjusting aspects of the transistor structure, the super skin can detect chemical substances in either vapor or liquid environments.

Regardless of what the sensors are detecting, they have to transmit electronic signals to get their data to the processing center, whether it is a human brain or a computer.

Having the sensors run on the sun's energy makes generating the needed power simpler than using batteries or hooking up to the electrical grid, allowing the sensors to be lighter and more mobile. And having solar cells that are stretchable opens up other applications.

A recent research paper by Bao, describing the stretchable solar cells, will appear in an upcoming issue ofAdvanced Materials. The paper details the ability of the cells to be stretched in one direction, but she said her group has since demonstrated that the cells can be designed to stretch along two axes.

The cells have a wavy microstructure that extends like an accordion when stretched. A liquid metal electrode conforms to the wavy surface of the device in both its relaxed and stretched states.

"One of the applications where stretchable solar cells would be useful is in fabrics for uniforms and other clothes," said Darren Lipomi, a graduate student in chemical engineering in Bao's lab and lead author of the paper.

"There are parts of the body, at the elbow for example, where movement stretches the skin and clothes," he said."A device that was only flexible, not stretchable, would crack if bonded to parts of machines or of the body that extend when moved." Stretchability would be useful in bonding solar cells to curved surfaces without cracking or wrinkling, such as the exteriors of cars, lenses and architectural elements.

The solar cells continue to generate electricity while they are stretched out, producing a continuous flow of electricity for data transmission from the sensors.

Bao said she sees the super skin as much more than a super mimic of human skin; it could allow robots or other devices to perform functions beyond what human skin can do.

"You can imagine a robot hand that can be used to touch some liquid and detect certain markers or a certain protein that is associated with some kind of disease and the robot will be able to effectively say, 'Oh, this person has that disease,'" she said."Or the robot might touch the sweat from somebody and be able to say, 'Oh, this person is drunk.'"

Finally, Bao has figured out how to replace the materials used in earlier versions of the transistor with biodegradable materials. Now, not only will the super skin be more versatile and powerful, it will also be more eco-friendly.

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New High-Performance Lithium-Ion Battery 'Top Candidate' for Electric Cars

A report on this innovation appears in ACS'Journal of the American Chemical Society.

Bruno Scrosati, Yang-Kook Sun, and colleagues point out that consumers have a great desire for electric vehicles, given the shortage and expense of petroleum. But a typical hybrid car can only go short distances on electricity alone, and they hold less charge in very hot or very cold temperatures. With the government push to have one million electric cars on U.S. roads by 2015, the pressure to solve these problems is high. To make electric vehicles a more realistic alternative to gas-powered automobiles, the researchers realized that an improved battery was needed.

The scientists developed a high-capacity, nanostructured, tin-carbon anode, or positive electrode, and a high-voltage, lithium-ion cathode, the negative electrode. When the two parts are put together, the result is a high-performance battery with a high energy density and rate capacity."On the basis of the performance demonstrated here, this battery is a top candidate for powering sustainable vehicles," the researchers say.

The authors acknowledge funding from WCU (World Class University) program through the Korea Science and Engineering Foundation.

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Physicists Isolate Bound States in Graphene-Superconductor Junctions

Led by University of Illinois physics professor Nadya Mason, the group published its findings in the journalNature Physics.

When a current is applied to a normal conductor, such as metal or graphene, it flows through the material as a stream of single electrons. By contrast, electrons travel in pairs in superconductors. Yet when a normal material is sandwiched between superconductors, the normal metal can carry the supercurrent.

Normal metals can adopt superconducting capacity because the paired electrons from the superconductor are translated to special electron-hole pairs in the normal metal, called Andreev bound states (ABS).

"If you have two superconductors with a normal metal between, you can actually transport the superconductivity across the normal material via these bound states, even though the normal material doesn't have the electron pairing that the superconductors do," Mason said.

ABS are extremely difficult to measure or to observe directly. Researchers can measure conduction and overall magnitude of a current, but have not been able to study individual ABS to understand the fundamental physics contributing to these unique states.

Mason's group developed a method of isolating individual ABS by connecting superconducting probes to tiny, nanoscale flakes of graphene called quantum dots. This confined the ABS to discrete energy levels within the quantum dot, allowing the researchers to measure the superconducting ABS individually and even to manipulate them.

"Before this, it wasn't really possible to understand the fundamentals of what is transporting the current," Mason said."Watching an individual bound state allows you to change one parameter and see how one mode changes. You can really get at a systematic understanding. It also allows you to manipulate ABS to use them for different things that just couldn't be done before."

Superconductor junctions have been proposed for use as superconducting transistors or bits for quantum computers, called qubits. Greater understanding of ABS may enable other applications as well. In addition, it may be possible to use the superconducting graphene quantum dots themselves as solid-state qubits.

"This is a unique case where we found something that we couldn't have discovered without using all of these different elements -- without the graphene, or the superconductor, or the quantum dot, it wouldn't have worked. All of these are really necessary to see this unusual state," Mason said.

The U.S. Department of Energy supported this work, conducted at the Frederick Seitz Materials Research Laboratory at Illinois.

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Compact High-Temperature Superconducting Cables Demonstrated

Described in a paper just published online, the new method involves winding multiple HTS-coated conductors around a multi-strand copper"former" or core. The superconducting layers are wound in spirals in alternating directions. One prototype cable is 6.5 millimeters (mm) in outer diameter and carries a current of 1,200 amperes; a second cable is 7.5 mm in diameter and carries a current as high as 2,800 amperes. They are roughly one-tenth the diameter of typical HTS cables used in the power grid. (Standard electrical transmission lines normally operate at currents below 1,000 amperes.)

HTS materials, which conduct electricity without resistance when cooled sufficiently (below 77 K, or minus 196 C/minus 321 F, for the new cables) with liquid nitrogen or helium gas, are used to boost efficiency in some power grids. The main innovation in the compact cables is the tolerance of newer HTS conductors to compressive strain that allows use of the unusually slender copper former, says developer Danko van der Laan, a University of Colorado scientist working at NIST.

"The knowledge I gained while working at NIST on electromechanical properties of high-temperature superconductors was very important for inventing the initial cable concept," van der Laan says."For instance, my discovery that the conductor survives large compressive strains made me realize that wrapping the conductor around a small diameter former would most likely work."

Van der Laan and NIST colleagues demonstrated the feasibility of the new concept by making several cables and testing their performance. They used an HTS material with a critical current that is less sensitive to strain than some other materials. Although the prototype cables are wound by hand, several manufacturers say mass production is feasible.

NIST researchers are now developing prototype compact HTS cables for the military, which requires small size and light weight as well as flexibility to pull transmission lines through conduits with tight bends. Beside power transmission, the flexible cabling concept could be used for superconducting transformers, generators, and magnetic energy storage devices that require high-current windings. The compact cables also could be used in high-field magnets for fusion and for medical applications such as next-generation magnetic resonance imaging and proton cancer treatment systems.

The work was supported in part by the U.S. Department of Energy.

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New Material Provides 25 Percent Greater Thermoelectric Conversion Efficiency

"What happened here has not happened anywhere else," said Evgenii Levin, associate scientist at Ames Laboratory and co-principal investigator on the effort, speaking of the significant boost in efficiency documented by the research. Along with Levin, the Ames Lab-based team included: Bruce Cook, scientist and co-principal investigator; Joel Harringa, assistant scientist II; Sergey Bud'ko, scientist; and Klaus Schmidt-Rohr, faculty scientist. Also taking part in the research was Rama Venkatasubramanian, who is director of the Center for Solid State Energetics at RTI International, located in North Carolina.

So-called thermoelectric materials that convert heat into electricity have been known since the early 1800s. One well-established group of thermoelectric materials is composed of tellurium, antimony, germanium and silver, and thus is known by the acronym"TAGS." Thermoelectricity is based on the movement of charge carriers from their heated side to their cooler side, just as electrons travel along a wire.

The process, known as the Seebeck effect, was discovered in 1821 by Thomas Johann Seebeck, a physicist who lived in what is now Estonia. A related phenomenon observed in all thermoelectric materials is known as the Peltier effect, named after French physicist Jean-Charles Peltier, who discovered it in 1834. The Peltier effect can be utilized for solid-state heating or cooling with no moving parts.

In the nearly two centuries since the discovery of the Seebeck and Peltier effects, practical applications have been limited due to the low efficiency with which the materials performed either conversion. Significant work to improve that efficiency took place during the 1950s, when thermoelectric conversion was viewed as an ideal power source for deep-space probes, explained team member Cook."Thermoelectric conversion was successfully used to power the Voyager, Pioneer, Galileo, Cassini, and Viking spacecrafts," he said.

Despite its use by NASA, the low efficiency of thermoelectric conversion still kept it from being harnessed for more down-to-earth applications -- even as research around the world continued in earnest."Occasionally, you would hear about a large increase in efficiency," Levin explained. But the claims did not hold up to closer scrutiny.

All that changed in 2010, when the Ames Laboratory researchers found that adding just one percent of the rare-earth elements cerium or ytterbium to a TAGS material was sufficient to boost its performance.

The results of the group's work appear online in the journalAdvanced Functional Materials.

The team has yet to understand exactly why such a small compositional change in the material is able to profoundly affect its properties. However, they theorize that doping the TAGS material with either of the two rare-earth elements could affect several possible mechanisms that influence thermoelectric properties.

Team member Schmidt-Rohr studied the materials using Ames Laboratory's solid-state nuclear magnetic resonance spectroscopy instruments. This enabled the researchers to verify that the one percent doping of cerium or ytterbium affected the structure of the thermoelectric material. In order to understand effect of magnetism of rare earths, team member Bud'ko studied magnetic properties of the materials."Rare-earth elements modified the lattice," said Levin, referring to the crystal structure of the thermoelectric materials.

The group plans to test the material in order to better understand why the pronounced change took place and, hopefully, to boost its performance further.

The durable and relatively easy-to-produce material has innumerable applications, including recycling waste heat from industrial refineries or using auto exhaust heat to help recharge the battery in an electric car."It's a very amazing area," Levin said, particularly since many years of prior research into TAGS materials enables researchers to understand their nature. Better understanding of the thermoelectric and their improvement can immediately result in applications at larger scale than now.

Additionally, the Ames Laboratory results -- dependent as they were on doping TAGS with small amounts of cerium or ytterbium -- provide yet more evidence of rare-earth elements' strategic importance. Cerium or ytterbium are members of a group of 15 lanthanides, deemed essential to just about every new technology from consumer electronics and cell phones to hybrid car batteries and generator motors in wind turbines. The Ames Laboratory has been a leader in rare-earth research going back to the closing days of World War II. Fears of shortages of rare-earth elements have caused these little-known materials to be a much-talked-about subject in the news lately.

Partial funding for this research was provided by the DARPA/DSO Program, along with the DOE Office of Science.

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Getting Cars Onto the Road Faster

The auto industry faces major challenges. New models are entering the market at ever shorter intervals, products are becoming more complex, and the trend towards electric cars requires modified vehicle structures. European production sites are coming under increasing cost pressure from low-wage countries. Cost reductions, shorter production times, new materials and innovative assembly techniques are needed if companies are to remain competitive. To achieve these goals, 23 business and research organizations are participating in the EU's Pegasus project (www.pegasus-eu.net). One of the research partners is the Fraunhofer Institute for Chemical Technology ICT in Pfinztal, which is contributing its expertise in the polymer engineering sector. The project partners have jointly developed a software platform to reduce development times and costs.

The Integrated Design and Engineering Environment (IDEE) is a CAD/CAE/CAM software system which is connected to an intelligent database. It analyzes the functional requirements of a product and identifies appropriate materials at an early stage of the development process. If, for example, a car roof is to be made in a different material than before, it is not necessary to conduct a new development process. Instead, the design engineers enter the component data into the software system, which assesses the information and then selects suitable materials and manufacturing processes. The platform also provides engineering guidelines for designing the tools that will be used to produce the component. The project partners have demonstrated how this platform could work on the example of a fender with integrated LED tail light."We used the original fender from a Smart. Our project demonstrates how this complex component can be produced more quickly and cheaply with new processing techniques, materials, bonding agents and tools," says Timo Huber, a scientist at Fraunhofer ICT. Instead of conventional lamps, the project partners fitted LED tail lights to the fender. This reduced the number of separate parts from eight to five, and the number of processing steps from twelve to five. Material and cost savings were also achieved by using conductor paths made of electrically conductive polymer. The conductive carbon nanotubes conduct the electricity from the connector to the LEDs and render metallic conductor structures superfluous.

A further example application: So that components such as the LED tail lights can be dismantled more quickly, they are bonded using a special adhesive. For this the research scientists at Fraunhofer ICT and their project partners developed a new microwave-active adhesive bonding system. When irradiated with microwaves the individual components lose their adhesion and can be easily taken apart. This means that parts can be efficiently recycled into different categories."In addition, we dyed the fender using newly developed pigments based on special nanoparticles," states Huber. These nanostructures can be worked in particularly evenly, to dye plastics such as polypropylene. This means fewer pigments are needed than usual."We have also taken the importance of protecting the climate into account. Further developments in local fiber reinforcement of structural vehicle components will reduce weight and therefore emissions of CO2," the scientist adds, and sums up:"All in all the IDEE system will shorten development times, cut the number of assembly steps and reduce the amount of material consumed." IDEE is still under development, but it can already be used to produce simple components. The software should be ready and available to the auto industry in about a year's time.

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Next-Generation Electronic Devices: Conduction, Surface States in Topological Insulator Nanoribbons Controlled

Perhaps most importantly, the surfaces of topological insulators enable the transport of spin-polarized electrons while preventing the"scattering" typically associated with power consumption, in which electrons deviate from their trajectory, resulting in dissipation.

Because of such characteristics, these materials hold great potential for use in future transistors, memory devices and magnetic sensors that are highly energy efficient and require less power.

In a study published Feb. 13 inNature Nanotechnology, researchers from UCLA's Henry Samueli School of Engineering and Applied Science and from the materials division of Australia's University of Queensland show the promise of surface-conduction channels in topological insulator nanoribbons made of bismuth telluride and demonstrate that surface states in these nanoribbons are"tunable" -- able to be turned on and off depending on the position of the Fermi level.

"Our finding enables a variety of opportunities in building potential new-generation, low-dissipation nanoelectronic and spintronic devices, from magnetic sensing to storage," said Kang L. Wang, the Raytheon Professor of Electrical Engineering at UCLA Engineering, whose team carried out the research.

Bismuth telluride is well known as a thermoelectric material and has also been predicted to be a three-dimensional topological insulator with robust and unique surface states. Recent experiments with bismuth telluride bulk materials have also suggested two-dimensional conduction channels originating from the surface states. But it has been a great challenge to modify surface conduction, because of dominant bulk contribution due to impurities and thermal excitations in such small-band-gap semiconductors.

The development of topological insulator nanoribbons has helped. With their large surface-to-volume ratios, these nanoribbons significantly enhance surface conditions and enable surface manipulation by external means.

Wang and his team used thin bismuth telluride nanoribbons as conducting channels in field-effect transistor structures. These rely on an electric field to control the Fermi level and hence the conductivity of a channel. The researchers were able to demonstrate for the first time the possibility of controlling surface states in topological insulator nanostructures.

"We have demonstrated a clear surface conduction by partially removing the bulk conduction using an external electric field," said Faxian Xiu, a UCLA staff research associate and lead author of the study."By properly tuning the gate voltage, very high surface conduction was achieved, up to 51 percent, which represents the highest values in topological insulators."

"This research is very exciting because of the possibility to build nanodevices with a novel operating principle," said Wang, who is also associate director of the California NanoSystems Institute (CNSI) at UCLA."Very similar to the development of graphene, the topological insulators could be made into high-speed transistors and ultra-high-sensitivity sensors."

The new findings shed light on the controllability of the surface spin states in topological insulator nanoribbons and demonstrate significant progress toward high surface electric conditions for practical device applications. The next step for Wang's team is to produce high-speed devices based on their discovery.

"The ideal scenario is to achieve 100 percent surface conduction with a complete insulating state in the bulk," Xiu said."Based on the current work, we are targeting high-performance transistors with power consumption that is much less than the conventional complementary metal-oxide semiconductors (CMOS) technology used typically in today's electronics."

Study collaborators Jin Zou, a professor of materials engineering at the University of Queensland; Yong Wang, a Queensland International Fellow; and Zou's team at the division of materials at the University of Queensland contributed significantly to this work. A portion of the research was also done in Alexandros Shailos' lab at UCLA.

The study was funded by the Focus Center Research Program -- Center on Functional Engineered Nano Architectonics (FENA) at UCLA Engineering; the U.S. Defense Advanced Research Projects Agency (DARPA); and the Australian Research Council. The research on topological insulators was pioneered by FENA's Shoucheng Zhang, a professor of physics at Stanford University.

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Researchers Predict Future of Electronic Devices, See Top Ten List of Expected Breakthroughs

The just-released February issue of the Journal of the Society for Information Display contains the first-ever critical review of current and future prospects for electronic paper functions -- in other words reviewing and critiquing the technologies that will bring us devices like

• full-color, high-speed, low-power e-readers;
• iPads that can be viewed in bright sunlight, or
• e-readers and iPads so flexible that they can be rolled up and put in a pocket.

The University of Cincinnati's Jason Heikenfeld, associate professor of electrical and computer engineering and an internationally recognized researcher in the field of electrofluidics, is the lead author on the paper titled"A Critical Review of the Present and Future Prospects for Electronic Paper." Others contributing to the article are industry researcher Paul Drzaic of Drzaic Consulting Services; research scientist Jong-Souk (John) Yeo of Hewlett-Packard's Imaging and Printing Group; and research scientist Tim Koch, who currently manages Hewlett-Packard's effort to develop flexible electronics.

Based on this latest article and his ongoing research and development related to e-paper devices, UC's Heikenfeld provides the following top ten list of electronic paper devices that consumers can expect both near term and in the next ten to 20 years.

Heikenfeld is part of a UC team that specializes in research and development of e-devices.

Coming later this year:

• Color e-readerswill be out in the consumer market by mid year in 2011. However, cautions Heikenfeld, the color will be muted as compared to what consumers are accustomed to, say, on an iPad. Researchers will continue to work toward next-generation (brighter) color in e-Readers as well as high-speed functionality that will eventually allow for point-and-click web browsing and video on devices like the Kindle.

Already in use but expansive adoption and breakthoughs imminent:

• Electronic shelf labels in grocery stores.Currently, it takes an employee the whole day to label the shelves in a grocery store. Imagine the cost savings if all such labels could be updated within seconds -- allowing for, say, specials for one type of consumer who shops at 10 a.m. and updated specials for other shoppers stopping in at 5:30 p.m. Such electronic shelf labels are already in use in Europe and the West Coast and in limited, experimental use in other locales. The breakthrough for use of such electronic labels came when they could be implemented as low-power devices. Explained Heikenfeld,"The electronic labels basically only consume significant power when they are changed. When it's a set, static message and price, the e-shelf label is consuming such minimal power -- thanks to reflective display technology -- that it's highly economical and effective." The current e-shelf labels are monochrome, and researchers will keep busy to create high-color labels with low-power needs.

• The new"no knobs" etch-a-sketch. This development allows children to draw with electronic ink and erase the whole screen with the push of a button. It was created based on technology developed in Ohio (Kent State University). Stated Heikenfeld,"Ohio institutions, namely the University of Cincinnati and Kent State, are international leaders in display and liquid optics technology."

• Technology in hot-selling Glow Boards will soon come to signage. Crayola's Glow Board is partially based on UC technology developments, which Crayola then licensed. While the toy allows children to write on a surface that lights up, the technology has many applications, and consumers can expect to see those imminently. These include indoor and outdoor sign displays that when turned off, seem to be clear windows. (Current LCD -- liquid crystal display -- sign technology requires extremely high power usage, and when turned off, provide nothing more than a non-transparent black background.)

Coming within two years:

• An e-device that will consume little power while also providing high function and color (video playing and web browsing) while also featuring good visibility in sunlight.Cautions Heikenfeld,"The color on this first-generation low-power, high-function e-device won't be as bright as what you get today from LCD (liquid crystal display) devices (like the iPad) that consume a lot of power. The color on the new low-power, high-function e-device will be about one third as bright as the color you commonly see on printed materials. Researchers, like those of us at UC, will continue to work to produce the Holy Grail of an e-device: bright color, high function (video and web browsing) with low power usage."

Coming within three to five years:

• Color adaptable e-device casings.The color and/or designed pattern of the plastic casing that encloses your cell phone will be adaptable. In other words, you'll be able to change the color of the phone itself to a professional black-and-white for work or to a bright and vivid color pattern for a social outing."This is highly achievable," said Heikenfeld, adding,"It will be able to change color either automatically by reading the color of your outfit that day or by means of a downloaded app. It's possible because of low-power, reflective technology" (wherein the displayed pattern or color change is powered by available ambient light vs. powered by an electrical charge).

Expect the same feature to become available in devices like appliances."Yes," said Heikenfeld,"We'll see a color-changing app, so that you can have significant portions of your appliances be one color one day and a different color or pattern the next."

• Bright-color but low-power digital billboards visible both night and day. Currently, the digital billboards commonly seen are based on LEDs (liquid crystal displays), which consume high levels of electric power and still lose color when in direct sunlight. Heikenfeld explained,"We have the technology that would allow these digital billboards to operate by simply reflecting ambient light, just like conventional printed billboards do. That means low power usage and good visibility for the displays even in bright sunlight. However, the color doesn't really sizzle yet, and many advertisers using billboards will not tolerate a washed-out color."

• Foldable or roll-it-up e-devices. Expect that the first-generation foldable e-devices will be monochrome. Color will come later. The first foldable e-devices will come from Polymer Vision in the Netherlands. Color is expected later, using licensed UC-developed technology. The challenge, according to Heikenfeld, in creating foldable e-devices has been the device screen, which is currently made of rigid glass. But what if the screen were a paper-thin plastic that rolled like a window shade? You'd have a device like an iPad that could be folded or rolled up tens of thousands of times. Just roll it up and stick it in your pocket.

Within ten to 20 years:

• e-Devices with magazine-quality color, viewable in bright sunlight but requiring low power."Think of this as the green iPad or e-Reader, combining high function and high color with low power requirements." said Heikenfeld.

• The e-Sheet, a virtually indestructible e-device that will be as thin and as rollable as a rubber place mat.It will be full color and interactive, while requiring low power to operate since it will charge via sunlight and ambient room light. However, it will be so"tough" and only use wireless connection ports, such that you can leave it out over night in the rain. In fact, you'll be able to wash it or drop it without damaging the thin, highly flexible casing.

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Nanonets Give Rust a Boost as Agent in Water Splitting's Hydrogen Harvest

Assistant Professor of Chemistry Dunwei Wang and his clean energy lab pioneered the development of Nanonets in 2008 and have since shown them to be a viable new platform for a number of energy applications by virtue of the increased surface area and improved conductivity of the nano-scale netting made from titanium disilicide, a readily available semiconductor.

Wang and his team report that coating the Nanonets with hematite, the plentiful mineral form of iron oxide, showed the mineral could absorb light efficiently and without the added expense of enhancing the material with an oxygen evolving catalyst.

The results flow directly from the introduction of the Nanonet platform, Wang said. While constructed of wires 1/400th the size of a human hair, Nanonets are highly conductive and offer significant surface area. They serve dual roles as a structural support and an efficient charge collector, allowing for maximum photon-to-charge conversion, Wang said.

"Recent research has shown that the use of a catalyst can boost the performance of hematite," said Wang."What we have shown is the potential performance of hematite at its fundamental level, without a catalyst. By using this unique Nanonet structure, we have shed new light on the fundamental performance capabilities of hematite in water splitting."

On its own, hematite faces natural limits in its ability to transport a charge. A photon can be absorbed, but has no place to go. By giving it structure and added conductivity, the charge transport abilities of hematite increase, said Wang. Water splitting, a chemical reaction that separates water into oxygen and hydrogen gas, can be initiated by passing an electric current through water. But that process is expensive, so gains in efficiency and conductivity are required to make large-scale water splitting an economically viable source for clean energy, Wang said.

"The result highlights the importance of charge transport in semiconductor-based water splitting, particularly for materials whose performance is limited by poor charge diffusion," the researchers report in the journal."Our design introduces material components to provide a dedicated charge transport pathway, alleviates the reliance on the materials' intrinsic properties, and therefore has the potential to greatly broaden where and how various existing materials can be used in energy-related applications."

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Neutron Analysis Reveals 'Two Doors Down' Superconductivity Link

Researchers at the Department of Energy's Oak Ridge National Laboratory and the University of Tennessee, using the Spallation Neutron Source's ARCS Wide Angular Range Chopper Spectrometer, performed spin-wave studies of magnetically ordered iron chalcogenides. They based their conclusions on comparisons with previous spin-wave data on magnetically ordered pnictides, another class of iron-based superconductors.

"As we analyze the spectra, we find that even though the nearest neighbor exchange couplings between chalcogenide and pnictide atoms are different, the next nearest neighbor exchange couplings are closely similar," said Pengcheng Dai, who has a joint appointment with ORNL's Neutron Sciences Directorate and the University of Tennessee.

Dai referred to theories that have suggested second-nearest-neighbor couplings could be responsible for the widely acclaimed but poorly understood properties of high-temperature superconductors.

"There are theories suggesting that it's the second nearest neighbor that drives the superconductivity," he said."Our discovery of similar next-nearest-neighbor couplings in these two iron-based systems suggests that superconductivity shares a common magnetic origin."

Oliver Lipscombe of the University of Tennessee, Dai and ORNL's Doug Abernathy used the ARCS time-of-flight instrument on the SNS to study spin waves of the chalcogenide iron-tellurium superconductor and compared these with iron pnictide superconductors. Scientists have been studying the iron-based superconductors since their discovery in 2008 to see if the dynamics behind their high-temperature superconducting properties -- in which electricity flows without resistance at temperatures well above absolute zero -- could help explain what was until recently thought to be exclusive to copper-oxide-based superconductors.

"Finding commonalities is always a good step when you're looking for a very basic understanding of a phenomenon like high-temperature superconductivity," said Abernathy, who is lead instrument scientist for the ARCS instrument.

The team's neutron scattering analysis of the materials was made possible by the high intensity of the neutron beams provided by the SNS, which is the world's most powerful pulsed neutron source. Neutrons, which carry no electric charge but can act as subatomic magnets, are well suited for studying atom-scale spin characteristics.

"Since the interactions in the high-temperature superconductors are so strong, measurement of these materials' spin waves requires beams of energetic neutrons that were unavailable to the research community at this intensity before the SNS," Abernathy said.

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Aluminum to Replace Copper as a Conductor in on-Board Power Systems

At first glance it is not at all clear why copper is still used as conductor in modern electric or semi-electric vehicles -- when aluminum is lighter and significantly less costly. However, before aluminum can replace copper in power supply systems, a number of technological challenges need to be surmounted. When temperatures are high -- and there are many places in a car where that is the case -- aluminum displays a distinct creep behavior. Conventional connectors could thus not be used, as they would become loose with time.

One possible alternative -- the use of aluminum-based elements in cables and copper-based elements in connection areas -- also entails problems. Because there is a high electrochemical potential between a copper contact and an aluminum cable, this kind of wiring would be very prone to corrosion. Besides, joining copper to aluminum is rather demanding with the current state of technology. In order to counteract the aforementioned difficulties, scientists of the chairs for High Voltage Technology and Power Transmission and for Metal Casting and Forming, in cooperation with the respective departments of the BMW Group, developed an innovative aluminum-based electrical connection concept in the project LEIKO.

A sheet metal cage, which is an electromagnetic compatibility requirement anyway, enhances the mechanical stability of the plug and guarantees the long-term support of the contact pressure spring. Because the necessary contact force is no longer provided by the contact elements themselves, the originally problematic creep behavior of aluminum turns into a contact stabilizing, and thus, positive property. This, in turn, also guarantees a constant contact force over a lifetime of ten years.

To this end the researchers came up with a special wedge-shaped geometry for the aluminum contacts. The aluminum creep now leads to the two contacts snuggling closer and closer together over time, thereby rendering the electrical connection better yet. Moreover, the consistent use of aluminum alloys and the ingenious application of precious metal plating made it possible to relocate the formation of corrosion-prone local elements to less critical locations in the system.

A further problem with substituting aluminum for copper is its lower electrical conductivity. In the case of high-power on-board systems in particular, the cable cross-sections, which are about 60 per cent larger, need to be taken into account in the construction of cable ducts and feed-throughs. One positive thing the scientists discovered was that because aluminum is very pliable, the standard values from copper cable processing, where bending radii are set based on the diameter, could also be used for aluminum.

In order to determine the long-term behavior of the coated aluminum contacts under even the rough conditions typical for motorized vehicles, the project partners, together with leading suppliers, have successfully initiated a further research project. Funded by the Bavarian Research Foundation (BFS), this project will deliver evidence on the aging behavior and thus the suitability of the concept by 2012.

Initial results indicate that the material substitution will lead to significant improvements in weight, cost, and ultimately emissions."We expect the high-voltage on-board systems of most electric vehicles to be based on aluminum by 2020. Aluminum will find its way into low-voltage on-board systems as well, because the price of copper will rise significantly with increasing demand," says Professor Udo Lindemann from the Institute of Product Development at the TU Muenchen.

The project finds its theoretical counterpart in the Collaborative Research Center (SFB) 768, Managing Cycles in Innovation Processes, funded by the German Research Foundation (DFG). It aims to bundle competencies from computer science, engineering, economics, and the social sciences in order to look into challenges at the interfaces of innovation processes along with partners from industry. The goal of this research is to use an interdisciplinary perspective to develop industry-relevant solutions in dealing with dynamic changes in company environments, as well as in company internal process landscapes.

Another aspect of the research conducted within SFB 768 is a student project to develop an electrically driven go-cart. In order to experience the manifold challenges of innovation management first-hand, the students started with a standard base structure and went through the entire development process for all subsystems of the vehicle. The results of the LEIKO project are also integrated into the student project -- the entire high-voltage on-board system is implemented in aluminum.

The results are to be incorporated in the TUM electro vehicle MUTE, which will be presented at the IAA 2011.

Publication: Langer, S.; Lindemann, U.: Managing Cycles in Development Processes -- Analysis and Classification of External Context Factors, in 17th International Conference on Engineering Design, M. N. Bergendahl, M. Grimheden, and L. Leifer, Eds. Stanford University, California, USA: Design Society, 2009, pp. 1-539 -- 1-550

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New Technique Boosts High-Power Potential for Gallium Nitride Electronics

"For future renewable technologies, such as the smart grid or electric cars, we need high-power semiconductor devices," says Merve Ozbek, a Ph.D. student at NC State and author of a paper describing the research."And power-handling capacity is important for the development of those devices."

Previous research into developing high power GaN devices ran into obstacles, because large electric fields were created at specific points on the devices' edge when high voltages were applied -- effectively destroying the devices. NC State researchers have addressed the problem by implanting a buffer made of the element argon at the edges of GaN devices. The buffer spreads out the electric field, allowing the device to handle much higher voltages.

The researchers tested the new technique on Schottky diodes -- common electronic components -- and found that the argon implant allowed the GaN diodes to handle almost seven times higher voltages. The diodes that did not have the argon implant broke down when exposed to approximately 250 volts. The diodes with the argon implant could handle up to 1,650 volts before breaking down.

"By improving the breakdown voltage from 250 volts to 1,650 volts, we can reduce the electrical resistance of these devices a hundredfold," says Dr. Jay Baliga, Distinguished University Professor of Electrical and Computer Engineering at NC State and co-author of the paper."That reduction in resistance means that these devices can handle ten times as much power."

The paper,"Planar, Nearly Ideal Edge Termination Technique for GaN Devices," is forthcoming from IEEE'sElectron Device Letters. The research was supported by NC State's Future Renewable Electric Energy Delivery and Management Systems Center, with funding from the National Science Foundation.

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'Tall Order' Sunlight-to-Hydrogen System Works, Neutron Analysis Confirms

Photosynthesis, the natural process carried out by plants, algae and some bacterial species, converts sunlight energy into chemical energy and sustains much of the life on earth. Researchers have long sought inspiration from photosynthesis to develop new materials to harness the sun's energy for electricity and fuel production.

In a step toward synthetic solar conversion systems, the ORNL researchers have demonstrated and confirmed with small-angle neutron scattering analysis that light harvesting complex II (LHC-II) proteins can self-assemble with polymers into a synthetic membrane structure and produce hydrogen.

The researchers envision energy-producing photoconversion systems similar to photovoltaic cells that generate hydrogen fuel, comparable to the way plants and other photosynthetic organisms convert light to energy.

"Making a, self-repairing synthetic photoconversion system is a pretty tall order. The ability to control structure and order in these materials for self-repair is of interest because, as the system degrades, it loses its effectiveness," ORNL researcher Hugh O'Neill, of the lab's Center for Structural Molecular Biology, said.

"This is the first example of a protein altering the phase behavior of a synthetic polymer that we have found in the literature. This finding could be exploited for the introduction of self-repair mechanisms in future solar conversion systems," he said.

Small angle neutron scattering analysis performed at ORNL's High Flux Isotope Reactor (HFIR) showed that the LHC-II, when introduced into a liquid environment that contained polymers, interacted with polymers to form lamellar sheets similar to those found in natural photosynthetic membranes.

The ability of LHC-II to force the assembly of structural polymers into an ordered, layered state -- instead of languishing in an ineffectual mush -- could make possible the development of biohybrid photoconversion systems. These systems would consist of high surface area, light-collecting panes that use the proteins combined with a catalyst such as platinum to convert the sunlight into hydrogen, which could be used for fuel.

The research builds on previous ORNL investigations into the energy-conversion capabilities of platinized photosystem I complexes -- and how synthetic systems based on plant biochemistry can become part of the solution to the global energy challenge.

"We're building on the photosynthesis research to explore the development of self-assembly in biohybrid systems. The neutron studies give us direct evidence that this is occurring," O'Neill said.

The researchers confirmed the proteins' structural behavior through analysis with HFIR's Bio-SANS, a small-angle neutron scattering instrument specifically designed for analysis of biomolecular materials.

"Cold source" neutrons, in which energy is removed by passing them through cryogenically chilled hydrogen, are ideal for studying the molecular structures of biological tissue and polymers.

The LHC-II protein for the experiment was derived from a simple source: spinach procured from a local produce section, then processed to separate the LHC-II proteins from other cellular components. Eventually, the protein could be synthetically produced and optimized to respond to light.

O'Neill said the primary role of the LHC-II protein is as a solar collector, absorbing sunlight and transferring it to the photosynthetic reaction centers, maximizing their output."However, this study shows that LHC-II can also carry out electron transfer reactions, a role not known to occur in vivo," he said.

The research team, which came from various laboratory organizations including its Chemical Sciences Division, Neutron Scattering Sciences Division, the Center for Structural Molecular Biology and the Center for Nanophase Materials Sciences, consisted of O'Neill, William T. Heller, and Kunlun Hong, all of ORNL; Dimitry Smolensky of the University of Tennessee; and Mateus Cardoso, a former postdoctoral researcher at ORNL now of the Laboratio Nacional de Luz Sincrotron in Brazil.

"That's one of the nice things about working at a national laboratory. Expertise is available from a variety of organizations," O'Neill said.

The work, published in the journalEnergy& Environmental Science, was supported with Laboratory-Directed Research and Development funding. HFIR is supported by the DOE Office of Science.

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High-Efficiency Photovoltaic Cells Developed

The cells developed by the UPC researchers have surpassed the 15% barrier -- the average efficiency of the most common photovoltaic cells. Specifically, a conversion efficiency (of incident light to electric power) of 20.5% has been achieved, which means the energy produced per unit of area can be increased by one third.

For example, thanks to the high efficiency of this new cell type, only 4.8 m² of photovoltaic panels would be needed to meet one family's annual energy needs (an average of about 4 kWh per day). This compares to an area of 6.5 m² for traditional cells.

The cells are made of crystalline silicon and work in a simple way, much as conventional cells do. The light captured by the cells generates charges that are drawn off at the panel contacts and transformed into an electric current."The goal is to generate a lot of charges that don't get lost -- that make it to the contacts," says Alcubilla, a member of the research group. Finally, after the light from the sun has been converted into electric current, it is fed into the power grid for domestic and industrial use.

The key to the success of the project was therefore to minimize losses, and by pursuing this approach the UPC researchers have managed to produce the most efficient silicon cells in Spain."We've done a lot of work on the conception and development of new materials and structures, and on the technology needed to optimize the entire process and achieve high levels of efficiency," says Alcubilla. The next step is to develop procedures that facilitate large-scale production.

The result achieved in this research (which has involved 38 trials since 2002) is comparable to those obtained in other research projects carried out in countries that are taking the lead in the field of photovoltaic energy. The maximum efficiency obtained for cells of this type is 24.7%, a record set by an Australian group at the University of New South Wales.

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New Wave: Efficient Source of Terahertz Radiation Developed

JILA is a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.

Terahertz radiation -- which falls between the radio and optical bands of the electromagnetic spectrum -- penetrates materials such as clothing and plastic but can be used to detect many substances that have unique absorption characteristics at these wavelengths. Terahertz systems are challenging to build because they require a blend of electronic and optical methods.

The JILA technology, described inOptics Letters,* is a new twist on a common terahertz source, a semiconductor surface patterned with metal electrodes and excited by ultrafast laser pulses. An electric field is applied across the semiconductor while near-infrared pulses lasting about 70 femtoseconds (quadrillionths of a second), produced 89 million times per second, dislodge electrons from the semiconductor. The electrons accelerate in the electric field and emit waves of terahertz radiation.

The JILA innovations eliminate two known problems with these devices. Adding a layer of silicon oxide insulation between the gallium arsenide semiconductor and the gold electrodes prevents electrons from becoming trapped in semiconductor crystal defects and producing spikes in the electric field. Making the electric field oscillate rapidly by applying a radiofrequency signal ensures that electrons generated by the light cannot react quickly enough to cancel the electric field.

The result is a uniform electric field over a large area, enabling the use of a large laser beam spot size and enhancing system efficiency. Significantly, users can boost terahertz power by raising the optical power without damaging the semiconductor. Sample damage was common with previous systems, even at low power. Among other advantages, the new technique does not require a microscopically patterned sample or high-voltage electronics. The system produces a peak terahertz field (20 volts per centimeter for an input power of 160 milliwatts) comparable to that of other methods.

While there are a number of different ways to generate terahertz radiation, systems using ultrafast lasers and semiconductors are commercially important because they offer an unusual combination of broad frequency range, high frequencies, and high intensity output.

NIST has applied for a provisional patent on the new technology. The system currently uses a large laser based on a titanium-doped sapphire crystal but could be made more compact by use of a different semiconductor and a smaller fiber laser, says senior author Steven Cundiff, a NIST physicist.

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World Can Be Powered by Alternative Energy, Using Today's Technology, in 20-40 Years, Experts Say

According to a new study coauthored by Stanford researcher Mark Z. Jacobson, we could accomplish all that by converting the world to clean, renewable energy sources and forgoing fossil fuels.

"Based on our findings, there are no technological or economic barriers to converting the entire world to clean, renewable energy sources," said Jacobson, a professor of civil and environmental engineering."It is a question of whether we have the societal and political will."

He and Mark Delucchi, of the University of California-Davis, have written a two-part paper inEnergy Policyin which they assess the costs, technology and material requirements of converting the planet, using a plan they developed.

The world they envision would run largely on electricity. Their plan calls for using wind, water and solar energy to generate power, with wind and solar power contributing 90 percent of the needed energy.

Geothermal and hydroelectric sources would each contribute about 4 percent in their plan (70 percent of the hydroelectric is already in place), with the remaining 2 percent from wave and tidal power.

Vehicles, ships and trains would be powered by electricity and hydrogen fuel cells. Aircraft would run on liquid hydrogen. Homes would be cooled and warmed with electric heaters -- no more natural gas or coal -- and water would be preheated by the sun.

Commercial processes would be powered by electricity and hydrogen. In all cases, the hydrogen would be produced from electricity. Thus, wind, water and sun would power the world.

The researchers approached the conversion with the goal that by 2030, all new energy generation would come from wind, water and solar, and by 2050, all pre-existing energy production would be converted as well.

"We wanted to quantify what is necessary in order to replace all the current energy infrastructure -- for all purposes -- with a really clean and sustainable energy infrastructure within 20 to 40 years," said Jacobson.

One of the benefits of the plan is that it results in a 30 percent reduction in world energy demand since it involves converting combustion processes to electrical or hydrogen fuel cell processes. Electricity is much more efficient than combustion.

That reduction in the amount of power needed, along with the millions of lives saved by the reduction in air pollution from elimination of fossil fuels, would help keep the costs of the conversion down.

"When you actually account for all the costs to society -- including medical costs -- of the current fuel structure, the costs of our plan are relatively similar to what we have today," Jacobson said.

One of the biggest hurdles with wind and solar energy is that both can be highly variable, which has raised doubts about whether either source is reliable enough to provide"base load" energy, the minimum amount of energy that must be available to customers at any given hour of the day.

Jacobson said that the variability can be overcome.

"The most important thing is to combine renewable energy sources into a bundle," he said."If you combine them as one commodity and use hydroelectric to fill in gaps, it is a lot easier to match demand."

Wind and solar are complementary, Jacobson said, as wind often peaks at night and sunlight peaks during the day. Using hydroelectric power to fill in the gaps, as it does in our current infrastructure, allows demand to be precisely met by supply in most cases. Other renewable sources such as geothermal and tidal power can also be used to supplement the power from wind and solar sources.

"One of the most promising methods of insuring that supply matches demand is using long-distance transmission to connect widely dispersed sites," said Delucchi. Even if conditions are poor for wind or solar energy generation in one area on a given day, a few hundred miles away the winds could be blowing steadily and the sun shining.

"With a system that is 100 percent wind, water and solar, you can't use normal methods for matching supply and demand. You have to have what people call a supergrid, with long-distance transmission and really good management," he said.

Another method of meeting demand could entail building a bigger renewable-energy infrastructure to match peak hourly demand and use the off-hours excess electricity to produce hydrogen for the industrial and transportation sectors.

Using pricing to control peak demands, a tool that is used today, would also help.

Jacobson and Delucchi assessed whether their plan might run into problems with the amounts of material needed to build all the turbines, solar collectors and other devices.

They found that even materials such as platinum and the rare earth metals, the most obvious potential supply bottlenecks, are available in sufficient amounts. And recycling could effectively extend the supply.

"For solar cells there are different materials, but there are so many choices that if one becomes short, you can switch," Jacobson said."Major materials for wind energy are concrete and steel and there is no shortage of those."

Jacobson and Delucchi calculated the number of wind turbines needed to implement their plan, as well as the number of solar plants, rooftop photovoltaic cells, geothermal, hydroelectric, tidal and wave-energy installations.

They found that to power 100 percent of the world for all purposes from wind, water and solar resources, the footprint needed is about 0.4 percent of the world's land (mostly solar footprint) and the spacing between installations is another 0.6 percent of the world's land (mostly wind-turbine spacing), Jacobson said.

One of the criticisms of wind power is that wind farms require large amounts of land, due to the spacing required between the windmills to prevent interference of turbulence from one turbine on another.

"Most of the land between wind turbines is available for other uses, such as pasture or farming," Jacobson said."The actual footprint required by wind turbines to power half the world's energy is less than the area of Manhattan." If half the wind farms were located offshore, a single Manhattan would suffice.

Jacobson said that about 1 percent of the wind turbines required are already in place, and a lesser percentage for solar power.

"This really involves a large scale transformation," he said."It would require an effort comparable to the Apollo moon project or constructing the interstate highway system."

"But it is possible, without even having to go to new technologies," Jacobson said."We really need to just decide collectively that this is the direction we want to head as a society."

Jacobson is the director of Stanford's Atmosphere/Energy Program and a senior fellow at Stanford's Woods Institute for the Environment and the Precourt Institute for Energy.

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Tuning Graphene Film So It Sheds Water

These are some of the potential applications for graphene, one of the hottest new materials in the field of nanotechnology, raised by the research of James Dickerson, assistant professor of physics at Vanderbilt.

Dickerson and his colleagues have figured out how to create a freestanding film of graphene oxide and alter its surface roughness so that it either causes water to bead up and run off or causes it to spread out in a thin layer.

"Graphene films are transparent and, because they are made of carbon, they are very inexpensive to make," Dickerson said."The technique that we use can be rapidly scaled up to produce it in commercial quantities."

His approach is documented in an article published online by the journalACS Nanoon Nov. 26.

Graphene is made up of sheets of carbon atoms arranged in rings -- something like molecular chicken wire. Not only is this one of the thinnest materials possible, but it is 10 times stronger than steel and conducts electricity better at room temperature than any other known material. Graphene's exotic properties have attracted widespread scientific interest, but Dickerson is one of the first to investigate how it interacts with water.

Many scientists studying graphene make it using a dry method, called"mechanical cleavage," that involves rubbing or scraping graphite against a hard surface. The technique produces sheets that are both extremely thin and extremely fragile. Dickerson's method can produce sheets equally as thin but considerable stronger than those made by other techniques. It is already used commercially to produce a variety of different coatings and ceramics. Known as electrophoretic deposition, this"wet" technique combines an electric field within a liquid medium to create nanoparticle films that can be transferred to another surface.

Dickerson and his colleagues found that they could change the manner in which the graphene oxide particles assemble into a film by varying the pH of the liquid medium and the electric voltage used in the process. One pair of settings lay down the particles in a"rug" arrangement that creates a nearly atomically smooth surface. A different pair of settings causes the particles to clump into tiny"bricks" forming a bumpy and uneven surface. The researchers determined that the rug surface causes water to spread out in a thin layer, while the brick surface causes water to bead up and run off.

Dickerson is pursuing an approach that could create film that enhances these water-associated properties, making them even more effective at either spreading out water or causing it to bead up and run off. There is considerable academic and commercial interest in the development of coatings with these enhanced properties, called super-hydrophobic and super-hydrophilic. Potential applications range from self-cleaning glasses and clothes to antifogging surfaces to corrosion protection and snow-load protection on buildings. However, effective, low-cost and durable coatings have yet to make it out of the laboratory.

Dickerson's idea is to apply his basic procedure to"fluorographene" -- a fluorinated version of graphene that is a two-dimensional version of Teflon -- recently produced by Kostya S. Novoselov and Andre K. Geim at the University of Manchester, who received the 2010 Nobel Prize for the discovery of graphene. Normal fluorographene under tension should be considerably more effective in repelling water than graphene oxide. So there is a good chance a"brick" version and a"rug" version would have extreme water-associated effects, Dickerson figures.

Graduate students Saad Hasan, John Rigueur, Robert Harl and Alex Krejci, postdoctoral research scientist Isabel Gonzalo-Juan and Associate Professor of Chemical and Biomolecular Engineering Bridget R. Rogers contributed to the research, which was funded by a Vanderbilt Discovery grant and by the National Science Foundation.

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Graphene and 'Spintronics' Combo Looks Promising

Graphene, a two-dimensional crystalline form of carbon, is being touted as a sort of"Holy Grail" of materials. It boasts properties such as a breaking strength 200 times greater than steel and, of great interest to the semiconductor and data storage industries, electric currents that can blaze through it 100 times faster than in silicon.

Spintronic devices are being hotly pursued because they promise to be smaller, more versatile, and much faster than today's electronics."Spin" is a quantum mechanical property that arises when a particle's intrinsic rotational momentum creates a tiny magnetic field. And spin has a direction, either"up" or"down." The direction can encode data in the 0s and 1s of the binary system, with the key here being that spin-based data storage doesn't disappear when the electric current stops.

"There is strong research interest in spintronic devices that process information using electron spins, because these novel devices offer better performance than traditional electronic devices and will likely replace them one day," says Kwok Sum Chan, professor of physics at the City University of Hong Kong"Graphene is an important material for spintronic devices because its electron spin can maintain its direction for a long time and, as a result, information stored isn't easily lost."

It is, however, difficult to generate a spin current in graphene, which would be a key part of carrying information in a graphene spintronic device. Chan and colleagues came up with a method to do just that. It involves using spin splitting in monolayer graphene generated by ferromagnetic proximity effect and adiabatic (a process that is slow compared to the speed of the electrons in the device) quantum pumping. They can control the degree of polarization of the spin current by varying the Fermi energy (the level in the distribution of electron energies in a solid at which a quantum state is equally likely to be occupied or empty), which they say is very important for meeting various application requirements.

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