Nanoscale crystals is far stronger and harder than iron

Researchers at North Carolina State University have created a substance far stronger and harder than conventional iron, and which retains these properties under extremely high temperatures – opening the door to a wide variety of potential applications, such as engine components that are exposed to high stress and high temperatures.

Iron that is made up of nanoscale crystals is far stronger and harder than its traditional counterpart, but the benefits of this “nano-iron” have been limited by the fact that its nanocrystalline structure breaks down at relatively modest temperatures. But the NC State researchers have developed an iron-zirconium alloy that retains its nanocrystalline structures at temperatures above 1,300 degrees Celsius – approaching the melting point of iron.

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Kris Darling, a Ph.D. student at NC State who led the project to develop the material, explains that the alloy’s ability to retain its nanocrystalline structure under high temperatures will allow for the material to be developed in bulk, because conventional methods of materials manufacture rely on heat and pressure.

In addition, Darling says the ability to work with the material at high temperatures will make it easier to form the alloy into useful shapes – for use as tools or in structural applications, such as engine parts.

The new alloy is also economically viable, since “it costs virtually the same amount to produce the alloy” as it does to create nano-iron, Darling says.

Dr. Carl C. Koch, an NC State professor of materials science engineering who worked on the project, explains that the alloy essentially consists of 1 percent zirconium and 99 percent iron. The zirconium allows the alloy to retain its nanocrystalline structure under high temperatures.

Source: North Carolina State University

Fungus improves corn-to-ethanol process

Growing a fungus in some of the leftovers from ethanol production can save energy, recycle more water and improve the livestock feed that's a co-product of fuel production, according to a team of researchers from Iowa State University and the University of Hawaii.

"The process could change ethanol production in dry-grind plants so much that energy costs can be reduced by as much as one-third," said Hans van Leeuwen, an Iowa State professor of civil, construction and environmental engineering and the leader of the research project.

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Van Leeuwen and the other researchers developing the technology -- Anthony L. Pometto III, a professor of food science and human nutrition; Mary Rasmussen, a graduate student in environmental engineering and biorenewable resources and technology; and Samir Khanal, a former Iowa State research assistant professor who's now an assistant professor of molecular biosciences and bioengineering at the University of Hawai'i at Manoa -- recently won the 2008 Grand Prize for University Research from the American Academy of Environmental Engineers for the project.

"Those chosen for prizes by an independent panel of distinguished experts address the broad range of modern challenges inherent in providing life-nurturing services for humans and protection of the environment," according to a statement from the academy. "... Their innovations and performance illustrate the essential role of environmental engineers in providing a healthy planet."

The Iowa State project is focused on using fungi to clean up and improve the dry-grind ethanol production process. That process grinds corn kernels and adds water and enzymes. The enzymes break the starches into sugars. The sugars are fermented with yeasts to produce ethanol.

The fuel is recovered by distillation, but there are about six gallons of leftovers for every gallon of fuel that's produced. Those leftovers, known as stillage, contain solids and other organic material. Most of the solids are removed by centrifugation and dried into distillers dried grains that are sold as livestock feed, primarily for cattle.

The remaining liquid, known as thin stillage, still contains some solids, a variety of organic compounds from corn and fermentation as well as enzymes. Because the compounds and solids can interfere with ethanol production, only about 50 percent of thin stillage can be recycled back into ethanol production. The rest is evaporated and blended with distillers dried grains to produce distillers dried grains with solubles.

The researchers added a fungus, Rhizopus microsporus, to the thin stillage and found it would feed and grow. The fungus removes about 80 percent of the organic material and all of the solids in the thin stillage, allowing the water and enzymes in the thin stillage to be recycled back into production.

The fungus can also be harvested. It's a food-grade organism that's rich in protein, certain essential amino acids and other nutrients. It can be dried and sold as a livestock feed supplement. Or it can be blended with distillers dried grains to boost its value as a livestock feed and make it more suitable for feeding hogs and chickens.

Van Leeuwen said all of that can save United States ethanol producers a lot of energy and money at current production levels:

* Eliminating the need to evaporate thin stillage would save ethanol plants up to $800 million a year in energy costs.
* Allowing more water recycling would reduce the industry's water consumption by as much as 10 billion gallons per year. And it allows producers to recycle enzymes in the thin stillage, saving about $60 million per year.
* Adding value and nutrients to the livestock feed produced by ethanol plants would grow the market for that feed by about $400 million per year.
* And the researchers' fungal process would improve the energy balance of ethanol production by reducing energy inputs so there is more of an energy gain.

Van Leeuwen estimated it would cost $11 million to start using the process in an ethanol plant that produces 100 million gallons of fuel per year. But, he said the cost savings at such a plant could pay off that investment in about six months.

The Iowa State research project is supported by grants of $78,806 from the Grow Iowa Values Fund, a state economic development program, and $80,000 from the U.S. Department of Agriculture through the Iowa Biotechnology Byproducts Consortium.

The researchers have filed for a patent on the technology and are looking for investors to commercialize the invention. And while the process needs to be proven at larger scales, there are high hopes it can do a lot to improve the efficiency of ethanol production.

"We will be saving ethanol producers money and energy," Pometto said. "That's the bottom line."

Source: Iowa State University

Smallest magnetic nanoparticles to date for cancer detection

Magnetic resonance imaging (MRI) can be a doctor's best friend for detecting a tumor in the body without resorting to surgery. MRI scans use pulses of magnetic waves and gauge the return signals to identify different types of tissue in the body, distinguishing bone from muscle, fluids from solids, and so on.

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Scientists have found that magnetic nanoparticles can be especially helpful in locating cancerous cell clusters during MRI scans. Like teeny guide missiles, the nanoparticles seek out tumor cells and attach themselves to them. Once the nanoparticles bind themselves to these cancer cells, the particles operate like radio transmitters, greatly aiding the MRI's detection capability.

Now, Brown University chemist Shouheng Sun and a team of researchers have created the smallest magnetic nanoparticles to date that can be employed on such seek-and-find missions. With a thinner coating, the particles also emit a stronger signal for the MRI to detect.

The results have been published online this week in the Journal of the American Chemical Society. Brown graduates students Jin Xie, Chenjie Xu and Sheng Peng collaborated on the research, along with Professor Xiaoyuan Chen and his associates from Stanford University.

The team created peptide-coated iron oxide nanoparticles — particles billionths of a meter in size. The researchers injected the particles into mice and tested their ability to locate a brain tumor cell called U87MG. Sun and his collaborators concentrated specifically on the nanoparticle's size and the thickness of the peptide coating, which ensures the nanoparticle attaches to the tumor cell.

Size is important because the trick is to create a nanoparticle that is small enough to navigate through the bloodstream and reach the diseased area. Bigger particles tend to stack up, creating the circulatory system's version of a traffic jam. Sun's team developed a nanoparticle that is about 8.4 nanometers in overall diameter — some six times smaller than the size of particles currently used in medicine.

"We wanted to make (the nanoparticle) very small, so the body's immune system won't recognize it," Sun explained. "That way, you let more particles interact with and attach to the tumor cell."

Nanoparticles are important in MRI detection because they enhance what scientists refer to as the "contrast" between the background, such as water molecules in the body, and a solid mass, such as a tumor.

The coating, while integral to the nanoparticles' attachment to the tumor cell, also is crucial to establishing the "signal-to-noise" ratio that a MRI uses. The thinner the coating, the stronger the emitted signal and vice versa. Sun's team outfitted their nanoparticles with a two-nanometer thick peptide coating — 10 times thinner than the coating available in popular MRI contrast agents such as Feridex. Sun's nanoparticles are like having a 50,000-watt radio transmitter versus a 150-watt station; it's easier for the MRI to "hear" the stronger signal and to hone in on the signal's source.

Another important feature of the team's work is discovering that the RGD peptide coating binds almost seamlessly to the U87MG tumor cell. The team plans to test the particle's ability to bind with other tumor cells in further animal experiments.

Potential health hazards of buckyballs studied

A new study into the potential health hazards of the revolutionary nano-sized particles known as ‘buckyballs’ predicts that the molecules are easily absorbed into animal cells, providing a possible explanation for how the molecules could be toxic to humans and other organisms.

Using computer simulations, University of Calgary biochemist Peter Tieleman, post-doctoral fellow Luca Monticelli and colleagues modeled the interaction between carbon-60 molecules and cell membranes and found that the particles are able to enter cells by permeating their membranes without causing mechanical damage. Their results are published in the current Advance Online Publication of Nature Nanotechnology, the world’s leading nanotechnology journal.

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“Buckyballs are already being made on a commercial scale for use in coatings and materials but we have not determined their toxicity,” said Tieleman, a Senior Scholar of the Alberta Heritage Foundation for Medical Research who specializes in membrane biophysics and biocomputing. “There are studies showing that they can cross the blood-brain barrier and alter cell functions, which raises a lot of questions about their toxicity and what impact they may have if released into the environment.”

Tieleman’s team used the high-powered computing resources of WestGrid, a partnership between 14 Western Canadian institutions, to run some of the cell behaviour simulations. The resulting model showed that buckyball particles are able to dissolve in cell membranes, pass into cells and re-form particles on the other side where they can cause damage to cells.

Spherical carbon-60 molecules were discovered in 1985, leading to the Nobel Prize in physics for researchers from the University of Sussex and Rice University who named the round, hollow molecules Buckminsterfullerene after renowned American architect Richard Buckminster Fuller, the inventor of the geodesic dome.

Popularly known as buckyballs, carbon-60 molecules form naturally in minute quantities under extreme conditions such as lightning strikes. They can also be produced artificially as spheres or oblong-shaped balls, known as fullerenes, and can be used to produce hollow fibers known as carbon nanotubes. Both substances are considered to be promising materials in the field of nanotechnology because of their incredible strength and heat resistance. Potential applications include the production of industrial materials, drug delivery systems, fuel cells and even cosmetics.

In recent years, much research has focused on the potential health and environmental impacts of buckyballs and carbon nanotubes. Fullerenes have been shown to cause brain damage in fish and inhaling carbon nanotubes results in lung damage similar to that caused by asbestos.

“Buckyballs commonly form into clumps that could easily be inhaled by a person as dust particles,” Tieleman said. “How they enter cells and cause damage is still poorly understood but our model shows a possible mechanism for how this might occur.”

Source: University of Calgary

The Most Advanced Quadruped Robot on Earth

Runs at 4 mph, climbs slopes up to 35 degrees, walks across rubble, and carries a 340 lb load.

BigDog is the alpha male of the Boston Dynamics family of robots. It is a quadruped robot that walks, runs, and climbs on rough terrain and carries heavy loads. BigDog is powered by a gasoline engine that drives a hydraulic actuation system. BigDog's legs are articulated like an animal’s, and have compliant elements that absorb shock and recycle energy from one step to the next. BigDog is the size of a large dog or small mule, measuring 1 meter long, 0.7 meters tall and 75 kg weight.

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BigDog has an on-board computer that controls locomotion, servos the legs and handles a wide variety of sensors. BigDog’s control system manages the dynamics of its behavior to keep it balanced, steer, navigate, and regulate energetics as conditions vary. Sensors for locomotion include joint position, joint force, ground contact, ground load, a laser gyroscope, and a stereo vision system. Other sensors focus on the internal state of BigDog, monitoring the hydraulic pressure, oil temperature, engine temperature, rpm, battery charge and others.

In separate trials, BigDog runs at 4 mph, climbs slopes up to 35 degrees, walks across rubble, and carries a 340 lb load.

BigDog is being developed by Boston Dynamics with the goal of creating robots that have rough-terrain mobility that can take them anywhere on Earth that people and animals can go. The program is funded by the Defense Advanced Research Project Agency (DARPA).

Watch a video: http://www.bostondynamics.com/content/sec.php?section=BigDog

New way to efficiently convert ethanol and other biofuels into hydrogenPermalink

Researchers here have found a way to convert ethanol and other biofuels into hydrogen very efficiently.

A new catalyst makes hydrogen from ethanol with 90 percent yield, at a workable temperature, and using inexpensive ingredients.

Umit Ozkan, professor of chemical and biomolecular engineering at Ohio State University, said that the new catalyst is much less expensive than others being developed around the world, because it does not contain precious metals, such as platinum or rhodium.

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"Rhodium is used most often for this kind of catalyst, and it costs around $9,000 an ounce," Ozkan said. "Our catalyst costs around $9 a kilogram."

She and her co-workers presented the research Wednesday, August 20 at the American Chemical Society meeting in Philadelphia.

The Ohio State catalyst could help make the use of hydrogen-powered cars more practical in the future, she said.

"There are many practical issues that need to be resolved before we can use hydrogen as fuel -- how to make it, how to transport it, how to create the infrastructure for people to fill their cars with it," Ozkan explained.

"Our research lends itself to what's called a 'distributed production' strategy. Instead of making hydrogen from biofuel at a centralized facility and transporting it to gas stations, we could use our catalyst inside reactors that are actually located at the gas stations. So we wouldn't have to transport or store the hydrogen -- we could store the biofuel, and make hydrogen on the spot."

The catalyst is inexpensive to make and to use compared to others under investigation worldwide. Those others are often made from precious metals, or only work at very high temperatures.

"Precious metals have high catalytic activity and -- in most cases -- high stability, but they're also very expensive. So our goal from the outset was to come up with a precious-metal-free catalyst, one that was based on metals that are readily available and inexpensive, but still highly active and stable. So that sets us apart from most of the other groups in the world."

The new dark gray powder is made from tiny granules of cerium oxide -- a common ingredient in ceramics -- and calcium, covered with even smaller particles of cobalt. It produces hydrogen with 90 percent efficiency at 660 degrees Fahrenheit (around 350 degrees Celsius) -- a low temperature by industrial standards.

"Whenever a process works at a lower temperature, that brings energy savings and cost savings," Ozkan said. “Also, if the catalyst is highly active and can achieve high hydrogen yields, we don’t need as much of it. That will bring down the size of the reactor, and its cost”.

The process starts with a liquid biofuel such as ethanol, which is heated and pumped into a reactor, where the catalyst spurs a series of chemical reactions that ultimately convert the liquid to a hydrogen-rich gas.

One of the biggest challenges the researchers faced was how to prevent "coking" -- the formation of carbon fragments on the surface of the catalyst. The combination of metals -- cerium oxide and calcium -- solved that problem, because it promoted the movement of oxygen ions inside the catalyst. When exposed to enough oxygen, the carbon, like the biofuel, is converted into a gas and gets oxidized; it becomes carbon dioxide.

At the end of the process, waste gases such as carbon monoxide, carbon dioxide and methane are removed, and the hydrogen is purified. To make the process more energy-efficient, heat exchangers capture waste heat and put that energy back into the reactor. Methane recovered in the process can be used to supply part of the energy.

Though this work was based on converting ethanol, Ozkan's team is now studying how to use the same catalyst with other liquid biofuels. Her coauthors on this presentation included Ohio State doctoral students Hua Song and Lingzhi Zhang.

Source: Ohio State University

Ferroelectric polymer-based capacitors can deliver power more rapidly and are much lighter than conventional batteries

The proliferation of solar, wind and even tidal electric generation and the rapid emergence of hybrid electric automobiles demands flexible and reliable methods of high-capacity electrical storage. Now a team of Penn State materials scientists is developing ferroelectric polymer-based capacitors that can deliver power more rapidly and are much lighter than conventional batteries.

"Electrical energy storage is very important for all electrical and electronic systems," says Qing Wang, associate professor of materials science and engineering. "Even renewable energy systems like solar cells need somewhere to store excess energy to be used at night."

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Wang and his research team report today (Aug. 20) at the 236th national American Chemical Society meeting in Philadelphia in two papers, on the development of power density tunable polymers and polymer ceramic nanocomposites as electric storage materials for capacitors. Currently, power conditioning is carried out by capacitors, but Wang believes that eventually properly tuned polymer capacitors could replace batteries.

"Traditional materials are ceramic materials which have high weight and are very fragile," says Wang. "Mobile electronics need light weight electrical energy storage."

The researchers, who include Wang, Yingying Lu, postdoctoral fellow, and Jason Claude, Junjun Li, graduate students in materials science and engineering, developed a polymer of poly(vinylidene fluoride) and trifluoroethylene which, with the addition of chlorotrifluoroethylene had a very high dielectric permittivity at room temperature. Permittivity is a measure of how much charge is stored in a material for a given electric field and is an indicator of how effective a material will be when storing energy in a capacitor. They found that by altering the amounts of the various chemical components of the polymer, they could tune the dielectric property and energy density.

Hybrid cars are a good target for ferroelectric polymer capacitors because they convert mechanical energy generated when, for example coasting downhill, convert it to electricity and charge batteries for use at other times. Conventional batteries are often heavy, and may not be able to deliver the power amounts needed for quick acceleration.

Wang and Li, report on a further modification of this ferroelectric polymer by adding nanoparticulate ceramics to further improve the energy density. Because ceramics often have higher permittivities than the polymers, they believed that combining polymers with high breakdown strength with ceramics of high permittivity would produce a composite material with a large energy storage capacity. Breakdown strength is a measure of the maximum electric field that an insulating material can withstand before it begins to conduct electricity. The higher the breakdown strength, the better a material is for a capacitor.

Unfortunately mixing nano particles of ceramic with polymers is not a simple action. The ceramic particles tend to clump and aggregate. If the two materials are not matched for electrical properties, their interface will breakdown at high electric fields and the ability of the composite to store energy will decrease, rather than increase. Wang and his team fine-tuned the dielectric particles to the polymer matrix by adding functionalized groups to the materials to match them. They also tried to control the mixing so that uniformly dispersed particles are spread through the matrix.

"Matching the permittivity and uniformly dispersing the ceramic nanoparticles is not easy," says Wang. "Both problems have to be tackled and solved at the same time for the material to have the desired characteristics."

Dielectric polymers like the ones Wang creates cannot only be used as capacitors, but could also substitute for the dielectric silicon dioxide layer currently used in computers. Because polymers are processed at room temperature, they are easily fabricated and they are extremely flexible. Their use would open the way for flexible electronics applications, such as foldable screens and computers.

Source: Penn State

Microorganisms that convert hydrocarbons to natural gas isolated

When a group of University of Oklahoma researchers began studying the environmental fate of spilt petroleum, a problem that has plagued the energy industry for decades, they did not expect to eventually isolate a community of microorganisms capable of converting hydrocarbons into natural gas.

The researchers found that the groundbreaking process—known as anaerobic hydrocarbon metabolism—can be used to stimulate methane gas production from older, more mature oil reservoirs like those in Oklahoma. The work has now led to the recognition that similar microorganisms may also be involved in problems ranging from the deterioration of fuels to the corrosion of pipelines.

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A new OU initiative led by Joseph Suflita, Director of the Institute for Energy and Environment within the Mewbourne College of Earth and Energy, brings together researchers from multiple disciplines and departments to attack the corrosion problems affecting pipelines, storage tanks and tankers as well as the deterioration of fuels inside such facilities. Suflita says, “The OU initiative is the only major U.S. initiative of its kind devoted to the problem of biodeterioration and biocorrosion.”

Biodeterioration and biocorrosion are fundamental microbiological processes that can cause pipelines, storage facilities and tankers to leak and contaminate the environment. “First, we have to understand how Mother Nature cleans up these spills and we can do this by studying the way microorganisms interact with hydrocarbons,” says Suflita. OU researchers have isolated some interesting organisms that metabolize hydrocarbons in the absence of oxygen—insight that was lacking for a long time.

OU researchers have extended their studies to how energy is produced in this country by investigating biocorrosion that leads to pipeline failures on the North Slope of Alaska. “We want to better understand how organisms eat through these pipelines. Several fundamental mechanisms cause this problem, but it is spotty and doesn’t occur all of a sudden. Rather, biocorrosion occurs over a long period of time, and we are using a series of new molecular and chemical tools to find out why and how this happens,” says Suflita.

“We think cells grow in communities that adhere to the inner surface of pipelines and form three-dimensional biofilms that can sometimes cause pitting. Once we understand what these microorganisms are doing, we can interrupt their processes or diagnose them more effectively. The science is rudimentary at this stage. The modern tools of molecular microbiology have not been applied yet, but a National Science Foundation grant, support from the DOE’s Joint Genome Institute and the cooperation of the energy industry, allowed us to study pipeline biocorrosion on the North Slope.”

Interruptions in energy supply are significant and cause price spikes that have global impact. Over 500,000 miles of pipeline that crisscross the United States carry over 75 percent of crude oil and 65 percent of refined product. Problems occur throughout the industry, in storage facilities, refineries and tankers, and have similar consequences. Microorganisms grow inside the pipelines because water often accompanies hydrocarbons pumped from the ground. As reservoirs age, more water is pumped creating an even greater problem.

“For many years, no one ever thought anaerobes could grow by metabolizing hydrocarbons in the absence of oxygen, but that is simply wrong. The organisms are actually quite good at it. The underlying mechanisms will be even more important as we introduce newer biofuels to augment our fossil fuel supply. We are putting new fuel combinations into the existing pipelines that service the entire country. The new biofuels can be less stable, so there is a different problem to deal with. The chemistry of biofuels may not allow us to store them as long and more research is needed to determine the stability, compatability and composition of such fuel mixtures.”

While biocorrosion and biodeterioration can be problematic, anaerobic hydrocarbon metabolism also has an upside. The OU researchers found that they can use their organisms to convert hydrocarbons in oil reservoirs to natural gas. “Because two-thirds of U.S. oil is still in place, we can use these organisms to convert residual hydrocarbons into natural gas and create a new source of domestic energy. The concept of anaerobic metabolism is an innovative process and the OU initiative is the only one of its kind in the United States at the present time. We are also experimenting with shales and other unconventional reservoirs.”

“Biotechnology can influence recovery and address some of today’s problems if we can understand how microorganisms degrade hydrocarbons in the absence of oxygen. OU is one of the top universities in the world to study anaerobic microbiology with 14 experts performing research in some aspect of this field. It is rare for universities to have even a single individual with this specialization. OU is an exciting place to be if you are an environmental microbiologist. This initiative has unified this group of experts and led to the groundbreaking research we have just begun to understand.”

“We know that bacterial cells communicate much like those that cause disease. If we know the language they use, we can send signals and interrupt their communications so they will change their behavior. The best way to treat the biocorrosion problem has not yet been determined. Active ongoing monitoring of pipelines tells us there is an ongoing process, but we need to get to the problem before it gets to the critical stage. Some and perhaps most microorganisms are not routinely monitored, so we have to understand the role they play in this process—information we can use to more effectively diagnose and treat the consequences.”

Source: University of Oklahoma

New way to fine-tune the light coming from quantum dots by manipulating them with pairs of lasers

Researchers from the National Institute of Standards and Technology (NIST) and the Joint Quantum Institute (JQI), a collaborative center of the University of Maryland and NIST, have reported a new way to fine-tune the light coming from quantum dots by manipulating them with pairs of lasers. Their technique, published in Physical Review Letters,* could significantly improve quantum dots as a source of pairs of “entangled” photons, a property with important applications in quantum information technologies. The accomplishment could accelerate development of powerful advanced cryptography applications, projected to be a key 21st-century technology.

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Entangled photons are a peculiar consequence of quantum mechanics. Tricky to generate, they remain interconnected even when separated by large distances. Merely observing one instantaneously affects the properties of the other. The entanglement can be used in quantum communication to pass an encryption key that is by its nature completely secure, as any attempt to eavesdrop or intercept the key would be instantly detected. One goal of the NIST-JQI team is to develop quantum dots as a convenient source of entangled photons.

Quantum dots are nanoscale regions of a semiconductor material similar to the material in computer processors but with special properties due to their tiny dimensions. Though they can be composed of tens of thousands of atoms, quantum dots in many ways behave almost as if they were single atoms. Unfortunately, almost is not good enough when it comes to the fragile world of quantum cryptography and next-generation information technologies. When energized, a quantum dot emits photons, or “particles” of light, just as a solitary atom does. But imperfections in the shape of a quantum dot cause what should be overlapping energy levels to separate. This ruins the delicate balance of the ideal state required to emit entangled photons.

To overcome this problem, the NIST-JQI team uses lasers to precisely control the energy levels of quantum dots, just as physicists have been doing with actual single atoms since the mid-1970s and, much more recently, with the artificial quantum dot variety. With their customized set-up, which includes two lasers—one shining from above the quantum dot and the other illuminating it from the side—the researchers were able to manipulate energy states in a quantum dot and directly measure its emissions. By adjusting the intensity of the laser beams, they were able to correct for imperfection-caused variations and generate more ideal signals. In so doing, the team was the first to demonstrate that laser-tuned quantum dots can efficiently generate photons one at a time, as required for quantum cryptography and other applications.

While the device currently still requires quite cold temperatures and sits in a liquid helium bath, it is compact enough to fit in the palm of your hand—an elegant setup that could be eventually implemented in quantum cryptography applications.

Source: NIST

Can biofuels be sustainable?

With oil prices skyrocketing, the search is on for efficient and sustainable biofuels. Research published this month in Agronomy Journal examines one biofuel crop contender: corn stover.

Corn stover is made up of the leaves and stalks of corn plants that are left in the field after harvesting the edible corn grain. Corn stover could supply as much as 25% of the biofuel crop needed by 2030.

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Scientists with the USDA-ARS Agroecosystem Unit located at the University of Nebraska examined the long-term sustainability of using corn stover as a biofuel crop.

When corn stover is not harvested as a biofuel crop, it can be left on the fields to restore vital nutrients to the soil. Full-scale harvesting of corn stover may deplete the soil.

Researchers measured the soil organic carbon levels and residue production over 14 years in fields planted continuously with corn, continuously with soybeans, and with a rotation of corn and soybeans. Organic carbon rates were found to stay steady or even increase in all three field types.

Gary Varvel and Wally Wilhelm, who conducted the study, said "These results suggest that a portion of corn stover could be harvested for biofuel production without reducing soil organic carbon levels in high yielding systems. However, since this study did not study the direct impact of stover removal, that aspect remains to be evaluated."

Research into the effects of residue removal on soil organic carbon levels in several different cropping systems is ongoing at this and several other USDA-ARS locations throughout the U.S. Much of this research is under the auspices of a multi-location CRIS project within ARS called REAP (Renewable Energy Assessment Project).

Full Article: http://agron.scijournals.org/cgi/content/abstract/100/4/1180

Source: American Society of Agronomy

Optical computing closer to reality

Scientists at the University of Pennsylvania have theorized a way to increase the speed of pulses of light that bound across chains of tiny metal particles to well past the speed of light by altering the particle shape. Application of this theory would use nanosized metal chains as building blocks for novel optoelectronic and optical devices, which would operate at higher frequencies than conventional electronic circuits. Such devices could eventually find applications in the developing area of high-speed optical computing, in which protons and light replace electrons and transistors for greater performance.

Colleagues in the Department of Bioengineering, Alexander A. Govyadinov and Vadim A. Markel, also of the Department of Radiology at Penn, published the study in a recent issue of the journal Physical Review B.

Recent developments in nanotechnology have enabled researchers to fabricate nanoparticle chains with great precision and fidelity. Penn’s research team took advantage of this technological advance by utilizing metallic nanoparticles as a chain of miniature waveguides that exchange light.

Currently, the advance is theoretical. But, from a practical standpoint, the creation of a metallic nanochain would provide the combination of smaller-diameter optical components coupled with larger bandwidth, making them optimal wave guiding materials. As the velocity of the light pulse increases, so too does the operating bandwidth of a waveguide. Increasing the bandwidth helps to increase the number of information channels, allowing more information to flow simultaneously through a waveguide.

Researchers investigated changing the shape of particles in an attempt to increase this bandwidth. Spherically-shaped nanoparticles, the shape used almost exclusively in early research, provide narrow bandwidths of light. As Markel and Govyadinov discovered, shaping the particles as prolate, cigar-shaped or oblate, saucer-shaped, spheroids boosted the velocities of surface plasmon pulses reflecting off the surface to 2.5 times the speed of light in a vacuum.

Reshaping the nanoparticles therefore resulted in an enormous increase in the operating bandwidth of the waveguide. As an additional bonus, constructing the chains from oblate spheroids results in decreased power loss as well.
The exceptional combination of small size, large bandwidth and relatively small losses may make these useful as building blocks for the light-based devices of the future.

Researchers have used light and metal to create special electromagnetic wave of electrons on the surface called plasmons for years. Just as light travels through optical fibers, surface plasmons propagate along a chain of closely spaced, metallic particles with each particle acting like a miniature beacon, receiving a signal from its neighbor and transmitting it further along the chain. Although chains of metallic particles are not practical for long-range communication due to rapid power loss, they are well suited for optoelectronic and optical devices in which achieving a small overall size is important.

Markel and Govyadinov’s theory may prove useful in overcoming sizing obstacles that complicate optics. Light cannot travel through an optical fiber if the fiber’s diameter is smaller than a micron. A particle chain like the one proposed by Penn researchers, however, could be as thin as 50 nanometers in diameter, a few hundred times thinner than any optical fiber, and still guide the surface plasmon waves.

An interesting conundrum arises from the work. The theory of relativity prohibits anything from moving faster than light.
“But what is a ‘thing’?” Markel said. “A very powerful flashlight directed at the moon would theoretically create a bright spot on its surface. By simply turning the flashlight sideways, the flashlight’s beam streaks across the sky at speeds far exceeding the speed of light. This evidence has long been known and dismissed, since the bright spot cannot be used for superluminal, or faster-than-light communication, between the earth and the moon. The fast motion of the bright spot is simply a geometrical artifact, similar, in some ways, to the point at which the two blades of closing scissors intersect. The theory of relativity does not concern such purely geometrical objects.”

The researchers believe there are, in fact, some superluminal "things" in nature. For example, it has been long theorized, and was demonstrated in a series of experiments in the last quarter of the 20th century, that electromagnetic pulses, or "wave packets," can propagate through material media with an overall velocity which is greater that the speed of light in vacuum. Although the superluminal wave packets cannot be used to transmit energy or information faster than the speed of light, and therefore do not contradict the theory of relativity, they are fascinating objects and can be utilized in optical communications.

The surface plasmon pulses discovered at Penn belong to the same class of superluminal wave packets. It is predicted that the superluminal properties of these pulses are much bolder than anything previously observed.

Source: University of Pennsylvania

The next ‘American Idol’? Ask your computer

New software shows promise in predicting breakout artists
Could a computer pick the next “American Idol”? The next Ludacris or Madonna?

New software by Israeli researchers promises to take much of the guesswork (and endless cover songs) out of figuring out which hip-hop or R & B artist will be the next "it" star in the United States. Using a mathematical formula to sort music requests logged by the massive Gnutella peer-to-peer file-sharing network, the researchers have boasted an enviable 15 percent to 30 percent success rate in automatically choosing artists or bands with breakout potential.

The solution, according to Tel Aviv University electrical engineer Yuval Shavitt and his colleagues, “is based on the observation that emerging artists, especially rappers, have a discernable stronghold of fans in their hometown area, where they are able to perform and market their music.”

Crucially, the researchers were able to extract geographic information from many of the 10 million to 40 million requests logged by Gnutella users every day. In some cases, the locations could be pinpointed to the level of a city borough, as in New York.

“What’s happening on the Internet is that it’s a whole collection of individual actions,” Shavitt said. “Such a huge collection of actions should have a very strong signal about many things, and in this case, it was so obvious that it should be a way to pick up trends — music, for example.”