Engineers build world's smallest, fastest nanomotor: Can fit inside a single cell

Engineers build world's smallest, fastest nanomotor: Can fit inside a single cell

  7:47:00 PM    Science Lover

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Researchers at the Cockrell School of Engineering at The University of Texas at Austin have built the smallest, fastest and longest-running tiny synthetic motor to date. The team's nanomotor is an important step toward developing miniature machines that could one day move through the body to administer insulin for diabetics when needed, or target and treat cancer cells without harming good cells.

Simple nanomotor. Credit: Image courtesy of University of Texas at Austin

With the goal of powering these yet-to-be invented devices, UT Austin engineers focused on building a reliable, ultra-high-speed nanomotor that can convert electrical energy into mechanical motion on a scale 500 times smaller than a grain of salt.

Mechanical engineering assistant professor Donglei "Emma" Fan led a team of researchers in the successful design, assembly and testing of a high-performing nanomotor in a nonbiological setting. The team's three-part nanomotor can rapidly mix and pump biochemicals and move through liquids, which is important for future applications. The team's study was published in a recent issue of Nature Communications.

Fan and her team are the first to achieve the extremely difficult goal of designing a nanomotor with large driving power.

With all its dimensions under 1 micrometer in size, the nanomotor could fit inside a human cell and is capable of rotating for 15 continuous hours at a speed of 18,000 RPMs, the speed of a motor in a jet airplane engine. Comparable nanomotors run significantly more slowly, from 14 RPMs to 500 RPMs, and have only rotated for a few seconds up to a few minutes.

Looking forward, nanomotors could advance the field of nanoelectromechanical systems (NEMS), an area focused on developing miniature machines that are more energy efficient and less expensive to produce. In the near future, the Cockrell School researchers believe their nanomotors could provide a new approach to controlled biochemical drug delivery to live cells.

To test its ability to release drugs, the researchers coated the nanomotor's surface with biochemicals and initiated spinning. They found that the faster the nanomotor rotated, the faster it released the drugs.

"We were able to establish and control the molecule release rate by mechanical rotation, which means our nanomotor is the first of its kind for controlling the release of drugs from the surface of nanoparticles," Fan said. "We believe it will help advance the study of drug delivery and cell-to-cell communications."

The researchers address two major issues for nanomotors so far: assembly and controls. The team built and operated the nanomotor using a patent-pending technique that Fan invented while studying at Johns Hopkins University. The technique relies on AC and DC electric fields to assemble the nanomotor's parts one by one.

In experiments, the researchers used the technique to turn the nanomotors on and off and propel the rotation either clockwise or counterclockwise. The researchers found that they could position the nanomotors in a pattern and move them in a synchronized fashion, which makes them more powerful and gives them more flexibility.

Fan and her team plan to develop new mechanical controls and chemical sensing that can be integrated into nanoelectromechanical devices. But first they plan to test their nanomotors near a live cell, which will allow Fan to measure how they deliver molecules in a controlled fashion.

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Computer as Smart as a 4-Year-Old? Researchers IQ Test New Artificial Intelligence System

Computer as Smart as a 4-Year-Old? Researchers IQ Test New Artificial Intelligence System

  7:45:00 PM    Science Lover

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Artificial and natural knowledge researchers at the University of Illinois at Chicago have IQ-tested one of the best available artificial intelligence systems to see how intelligent it really is.

Artificial and natural knowledge researchers IQ-tested 
one of the best available artificial intelligence systems 
and learned that it's about as smart as the average 
4-year-old. (Credit: © Spofi / Fotolia)

Turns out it's about as smart as the average 4-year-old, they will report July 17 at the U.S. Artificial Intelligence Conference in Bellevue, Wash.

The UIC team put ConceptNet 4, an artificial intelligence system developed at M.I.T., through the verbal portions of the Weschsler Preschool and Primary Scale of Intelligence Test, a standard IQ assessment for young children.

They found ConceptNet 4 has the average IQ of a young child. But unlike most children, the machine's scores were very uneven across different portions of the test.

"If a child had scores that varied this much, it might be a symptom that something was wrong," said Robert Sloan, professor and head of computer science at UIC, and lead author on the study.

Sloan said ConceptNet 4 did very well on a test of vocabulary and on a test of its ability to recognize similarities.

"But ConceptNet 4 did dramatically worse than average on comprehension­the 'why' questions," he said.

One of the hardest problems in building an artificial intelligence, Sloan said, is devising a computer program that can make sound and prudent judgment based on a simple perception of the situation or facts-the dictionary definition of commonsense.

Commonsense has eluded AI engineers because it requires both a very large collection of facts and what Sloan calls implicit facts-things so obvious that we don't know we know them. A computer may know the temperature at which water freezes, but we know that ice is cold.

"All of us know a huge number of things," said Sloan. "As babies, we crawled around and yanked on things and learned that things fall. We yanked on other things and learned that dogs and cats don't appreciate having their tails pulled." Life is a rich learning environment.

"We're still very far from programs with commonsense-AI that can answer comprehension questions with the skill of a child of 8," said Sloan. He and his colleagues hope the study will help to focus attention on the "hard spots" in AI research.

Study coauthors are UIC professors Stellan Ohlsson of psychology and Gyorgy Turan of mathematics, statistics and computer science; and UIC mathematical computer science undergraduate student Aaron Urasky.

The study was supported by award N00014-09-1-0125 from the Office of Naval Research and grant CCF-0916708 from the National Science Foundation.

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For better batteries, just add water

For better batteries, just add water

  12:29:00 AM    Science Lover

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A new type of lithium-ion battery that uses aqueous iodide ions in an aqueous cathode configuration provides twice the energy density of conventional lithium-ion batteries.

A new type of lithium-ion battery that uses aqueous iodide ions
in an aqueous cathode configuration provides twice the energy
density of conventional lithium-ion batteries.

Lithium-ion batteries are now found everywhere in devices such as cellular phones and laptop computers, where they perform well. In automotive applications, however, engineers face the challenge of squeezing enough lithium-ion batteries onto a vehicle to provide the desired power and range without introducing storage and weight issues. Hye Ryung Byon, Yu Zhao and Lina Wang from the RIKEN Byon Initiative Research Unit have now developed a lithium-iodine battery system with twice the energy density of conventional lithium-ion batteries.

Byon's team is involved in alternative energy research and, specifically, improving the performance of lithium-based battery technologies. In their research they turned to an 'aqueous' system in which the organic electrolyte in conventional lithium-ion cells is replaced with water. Such aqueous lithium battery technologies have gained attention among alternative energy researchers because of their greatly reduced fire risk and environmental hazard. Aqueous solutions also have other advantages, which include an inherently high ionic conductivity.

For their battery system, the researchers investigated an 'aqueous cathode' configuration (Fig. 1), which accelerates reduction and oxidation reactions to improve battery performance. Finding suitable reagents for the aqueous cathode, however, proved to be a tricky proposition. According to Byon, water solubility is the most important criterion for screening new materials, since this parameter determines the battery's energy density. Furthermore, the redox reaction has to take place in a restricted voltage range in order to avoid water electrolysis. An extensive search led the researchers to produce the first-ever lithium battery involving aqueous iodine—an element with high water solubility and a pair of ions, known as the triiodide/iodide redox couple, that readily undergo aqueous electrochemical reactions.

The team constructed a prototype aqueous cathode device and found the energy density to be nearly double that of a conventional lithium-ion battery, thanks to the high solubility of the triiodide/iodide ions. Their battery had high and near-ideal power storage capacities and could be successfully recharged hundreds of times, avoiding a problem that plagues other alternative high-energy-density lithium-ion batteries. Microscopy analysis revealed that the cathode collector remained untouched after 100 charge/discharge cycles with no observable corrosion or precipitate formation.

Byon and colleagues now plan to develop a three-dimensional, microstructured current collector that could enhance the diffusion-controlled triiodide/iodide process and accelerate charge and discharge. They are also seeking to raise energy densities even further by using a flowing-electrode configuration that stores aqueous 'fuel' in an external reservoir—a modification that should make this low-cost, heavy metal-free design more amenable to electric vehicle specifications.
More information: 1.Zhao, Y., Wang, L. & Byon, H. R. High-performance rechargeable lithium-iodine batteries using triiodide/iodide redox couples in an aqueous cathode. Nature Communications 4, 1896 (2013). dx.doi.org/10.1038/ncomms2907

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Biological Transistor Enables Computing Within Living Cells

Biological Transistor Enables Computing Within Living Cells

  10:14:00 AM    Science Lover

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When Charles Babbage prototyped the first computing machine in the 19th century, he imagined using mechanical gears and latches to control information. ENIAC, the first modern computer developed in the 1940s, used vacuum tubes and electricity. Today, computers use transistors made from highly engineered semiconducting materials to carry out their logical operations.

Artist's rendering of cells. (Credit: © Jezper / Fotolia)

And now a team of Stanford University bioengineers has taken computing beyond mechanics and electronics into the living realm of biology. In a paper to be published March 28 in Science, the team details a biological transistor made from genetic material -- DNA and RNA -- in place of gears or electrons. The team calls its biological transistor the "transcriptor."

"Transcriptors are the key component behind amplifying genetic logic -- akin to the transistor and electronics," said Jerome Bonnet, PhD, a postdoctoral scholar in bioengineering and the paper's lead author.

The creation of the transcriptor allows engineers to compute inside living cells to record, for instance, when cells have been exposed to certain external stimuli or environmental factors, or even to turn on and off cell reproduction as needed.

"Biological computers can be used to study and reprogram living systems, monitor environments and improve cellular therapeutics," said Drew Endy, PhD, assistant professor of bioengineering and the paper's senior author.

The biological computer

In electronics, a transistor controls the flow of electrons along a circuit. Similarly, in biologics, a transcriptor controls the flow of a specific protein, RNA polymerase, as it travels along a strand of DNA.

"We have repurposed a group of natural proteins, called integrases, to realize digital control over the flow of RNA polymerase along DNA, which in turn allowed us to engineer amplifying genetic logic," said Endy.

Using transcriptors, the team has created what are known in electrical engineering as logic gates that can derive true-false answers to virtually any biochemical question that might be posed within a cell.

They refer to their transcriptor-based logic gates as "Boolean Integrase Logic," or "BIL gates" for short.

Transcriptor-based gates alone do not constitute a computer, but they are the third and final component of a biological computer that could operate within individual living cells.

Despite their outward differences, all modern computers, from ENIAC to Apple, share three basic functions: storing, transmitting and performing logical operations on information.

Last year, Endy and his team made news in delivering the other two core components of a fully functional genetic computer. The first was a type of rewritable digital data storage within DNA. They also developed a mechanism for transmitting genetic information from cell to cell, a sort of biological Internet.

It all adds up to creating a computer inside a living cell.

Boole's gold

Digital logic is often referred to as "Boolean logic," after George Boole, the mathematician who proposed the system in 1854. Today, Boolean logic typically takes the form of 1s and 0s within a computer. Answer true, gate open; answer false, gate closed. Open. Closed. On. Off. 1. 0. It's that basic. But it turns out that with just these simple tools and ways of thinking you can accomplish quite a lot.

"AND" and "OR" are just two of the most basic Boolean logic gates. An "AND" gate, for instance, is "true" when both of its inputs are true -- when "a" and "b" are true. An "OR" gate, on the other hand, is true when either or both of its inputs are true.

In a biological setting, the possibilities for logic are as limitless as in electronics, Bonnet explained. "You could test whether a given cell had been exposed to any number of external stimuli -- the presence of glucose and caffeine, for instance. BIL gates would allow you to make that determination and to store that information so you could easily identify those which had been exposed and which had not," he said.

By the same token, you could tell the cell to start or stop reproducing if certain factors were present. And, by coupling BIL gates with the team's biological Internet, it is possible to communicate genetic information from cell to cell to orchestrate the behavior of a group of cells.

"The potential applications are limited only by the imagination of the researcher," said co-author Monica Ortiz, a PhD candidate in bioengineering who demonstrated autonomous cell-to-cell communication of DNA encoding various BIL gates.

Building a transcriptor

To create transcriptors and logic gates, the team used carefully calibrated combinations of enzymes -- the integrases mentioned earlier -- that control the flow of RNA polymerase along strands of DNA. If this were electronics, DNA is the wire and RNA polymerase is the electron.

"The choice of enzymes is important," Bonnet said. "We have been careful to select enzymes that function in bacteria, fungi, plants and animals, so that bio-computers can be engineered within a variety of organisms."

On the technical side, the transcriptor achieves a key similarity between the biological transistor and its semiconducting cousin: signal amplification.

With transcriptors, a very small change in the expression of an integrase can create a very large change in the expression of any two other genes.

To understand the importance of amplification, consider that the transistor was first conceived as a way to replace expensive, inefficient and unreliable vacuum tubes in the amplification of telephone signals for transcontinental phone calls. Electrical signals traveling along wires get weaker the farther they travel, but if you put an amplifier every so often along the way, you can relay the signal across a great distance. The same would hold in biological systems as signals get transmitted among a group of cells.

"It is a concept similar to transistor radios," said Pakpoom Subsoontorn, a PhD candidate in bioengineering and co-author of the study who developed theoretical models to predict the behavior of BIL gates. "Relatively weak radio waves traveling through the air can get amplified into sound."

Public-domain biotechnology

To bring the age of the biological computer to a much speedier reality, Endy and his team have contributed all of BIL gates to the public domain so that others can immediately harness and improve upon the tools.

"Most of biotechnology has not yet been imagined, let alone made true. By freely sharing important basic tools everyone can work better together," Bonnet said.

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Using 3-D Printing and Injectable Molds, Bioengineered Ears Look and Act Like the Real Thing

Using 3-D Printing and Injectable Molds, Bioengineered Ears Look and Act Like the Real Thing

  9:17:00 AM    Science Lover

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Cornell bioengineers and physicians have created an artificial ear -- using 3-D printing and injectable molds -- that looks and acts like a natural ear, giving new hope to thousands of children born with a congenital deformity called microtia.

A 3-D printer in Weill Hall deposits cells encapsulated in a hydrogel that will develop into new ear tissue. The printer takes instructions from a file built from 3-D photographs of human ears taken with a scanner in Rhodes Hall. (Credit: Lindsay France/University Photography)

In a study published online Feb. 20 in PLOS One, Cornell biomedical engineers and Weill Cornell Medical College physicians described how 3-D printing and injectable gels made of living cells can fashion ears that are practically identical to a human ear. Over a three-month period, these flexible ears grew cartilage to replace the collagen that was used to mold them.

"This is such a win-win for both medicine and basic science, demonstrating what we can achieve when we work together," said co-lead author Lawrence Bonassar, associate professor of biomedical engineering.

The novel ear may be the solution reconstructive surgeons have long wished for to help children born with ear deformity, said co-lead author Dr. Jason Spector, director of the Laboratory for Bioregenerative Medicine and Surgery and associate professor of plastic surgery at Weill Cornell in New York City.

"A bioengineered ear replacement like this would also help individuals who have lost part or all of their external ear in an accident or from cancer," Spector said. Replacement ears are usually constructed with materials that have a Styrofoam-like consistency, or sometimes, surgeons build ears from a patient's harvested rib. This option is challenging and painful for children, and the ears rarely look completely natural or perform well, Spector said.

To make the ears, Bonassar and colleagues started with a digitized 3-D image of a human subject's ear, and converted the image into a digitized "solid" ear using a 3-D printer to assemble a mold.

This Cornell-developed, high-density gel is similar to the consistency of Jell-o when the mold is removed. The collagen served as a scaffold upon which cartilage could grow.

The process is also fast, Bonassar added: "It takes half a day to design the mold, a day or so to print it, 30 minutes to inject the gel, and we can remove the ear 15 minutes later. We trim the ear and then let it culture for several days in nourishing cell culture media before it is implanted."

The incidence of microtia, which is when the external ear is not fully developed, varies from almost 1 to more than 4 per 10,000 births each year. Many children born with microtia have an intact inner ear, but experience hearing loss due to the missing external structure.

Spector and Bonassar have been collaborating on bioengineered human replacement parts since 2007. The researchers specifically work on replacement human structures that are primarily made of cartilage -- joints, trachea, spine, nose -- because cartilage does not need to be vascularized with a blood supply in order to survive.

"Using human cells, specifically those from the same patient, would reduce any possibility of rejection," Spector said.

He added that the best time to implant a bioengineered ear on a child would be when they are about 5 or six 6 old. At that age, ears are 80 percent of their adult size. If all future safety and efficacy tests work out, it might be possible to try the first human implant of a Cornell bioengineered ear in as little as three years, Spector said.

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Complex Logic Circuit from Bacterial Genes

Complex Logic Circuit from Bacterial Genes

  11:34:00 AM    Science Lover

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By force of habit we tend to assume computers are made of silicon, but there is actually no necessary connection between the machine and the material. All that an engineer needs to do to make a computer is to find a way to build logic gates -- the elementary building blocks of digital computers -- in whatever material is handy.

Just as electronic circuits are made from resistors, capacitors 
and transistors, biological circuits can be made from genes 
and regulatory proteins. Engineer Tae Seok Moon’s dream is 
to design modular “genetic parts” that can be used to build 
logic controllers inside microbes that will program them to 
make fuel, clean up pollutants, or kill infectious bacteria 
or cancerous cells. (Credit: © madarakis / Fotolia)

So logic gates could theoretically be made of pipes of water, channels for billiard balls or even mazes for soldier crabs.

By comparison Tae Seok Moon's ambition, which is to build logic gates out of genes, seems eminently practical. As a postdoctoral fellow in the lab of Christopher Voigt, PhD, a synthetic biologist at the Massachusetts Institute of Technology, he recently made the largest gene (or genetic) circuit yet reported.

Moon, PhD, now an assistant professor of energy, environmental and chemical engineering in the School of Engineering & Applied Science at Washington University in St. Louis is the lead author of an article describing the project in the Oct. 7 issue of Nature. Voigt is the senior author.

The tiny circuits constructed from these gene gates and others like them may one day be components of engineered cells that will monitor and respond to their environments.

The number of tasks they could undertake is limited only by evolution and human ingenuity. Janitor bacteria might clean up pollutants, chemical-engineer bacteria pump out biofuels and miniature infection-control bacteria might bustle about killing pathogens.

How to make an AND gate out of genes

The basis of modern computers is the logic gate, a device that makes simple comparisons between the bits, the 1s and 0s, in which computers encode information. Each logic gate has multiple inputs and one output. The output of the gate depends on the inputs and the operation the gate performs.

An AND gate, for example, turns on only if all of its inputs are on. An OR gate turns on if any of its inputs are on.

Suggestively, genes are turned on or off when a transcription factor binds to a region of DNA adjacent to the gene called a promotor.

To make an AND gate out of genes, however, Moon had to find a gene whose activation is controlled by at least two molecules, not one. So only if both molecule 1 AND molecule 2 are present will the gene be turned on and translated into protein.

Such a genetic circuit had been identified in Salmonella typhimurium, the bacterium that causes food poisoning. In this circuit, the transcription factor can bind to the promotor of a gene only if a molecule called a chaperone is present. This meant the genetic circuit could form the basis of a two-input AND gate.

The circuit Moon eventually built consisted of four sensors for four different molecules that fed into three two-input AND gates. If all four molecules were present, all three AND gates turned on and the last one produced a reporter protein that fluoresced red, so that the operation of the circuit could be easily monitored.

In the future, Moon says, a synthetic bacterium with this circuit might sense four different cancer indicators and, in the presence of all four, release a tumor-killing factor.

Crosstalk and timing faults

There are huge differences, of course, between the floppy molecules that embody biological logic gates and the diodes and transistors that embody electronic ones.

Engineers designing biological circuits worry a great deal about crosstalk, or interference. If a circuit is to work properly, the molecules that make up one gate cannot bind to molecules that are part of another gate.

This is much more of a problem in a biological circuit than in an electronic circuit because the interior of a cell is a kind of soup where molecules mingle freely.

To ensure that there wouldn't be crosstalk among his AND gates, Moon mined parts for his gates from three different strains of bacteria: Shigella flexneri and Pseudomonas aeruginosa, as well as Salmonella.

Although the parts from the three different strains were already quite dissimilar, he made them even more so by subjecting them to error-prone copying cycles and screening the copies for ones that were even less prone to crosstalk (but still functional).

Another problem Moon faced is that biological circuits, unlike electronic ones, don't have internal clocks that keep the bits moving through the logic gates in lockstep. If signals progress through layers of gates at different speeds, the output of the entire circuit may be wrong, a problem called a timing fault.

Experiments designed to detect such faults in the synthetic circuit showed that they didn't occur, probably because the chaperones for one layer of logic gates degrades before the transcription factors for the next layer are generated, and this forces a kind of rhythm on the circuit.

Hijacking a bacterium's controller

"We're not trying to build a computer out of biological logic gates," Moon says. "You can't build a computer this way. Instead we're trying to make controllers that will allow us to access all the things biological organisms do in simple, programmable ways."

"I see the cell as a system that consists of a sensor, a controller (the logic circuit), and an actuator," he says. "This paper covers work on the controller, but eventually the controller's output will drive an actuator, something that will do work on the cell's surroundings. "

An synthetic bacterium designed by a friend of Moon's at Nanyang Technological University in Singapore senses signaling molecules released by the pathogen Pseudomonas aeruginosa. When the molecules reach a high enough concentration, the bacterium generates a toxin and a protein that causes it to burst, releasing the toxin, and killing nearby P. aeruginosa.

"Silicon cannot do that," Moon says.

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New Energy Source for Future Medical Implants: Sugar

New Energy Source for Future Medical Implants: Sugar

  7:50:00 PM    Science Lover

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MIT engineers have developed a fuel cell that runs on the same sugar that powers human cells: glucose. This glucose fuel cell could be used to drive highly efficient brain implants of the future, which could help paralyzed patients move their arms and legs again.

This silicon wafer consists of glucose fuel cells of varying sizes; 
the largest is 64 by 64 mm. Image: (Credit: Sarpeshkar Lab)

The fuel cell, described in the June 12 edition of the journal PLoS ONE, strips electrons from glucose molecules to create a small electric current. The researchers, led by Rahul Sarpeshkar, an associate professor of electrical engineering and computer science at MIT, fabricated the fuel cell on a silicon chip, allowing it to be integrated with other circuits that would be needed for a brain implant.

The idea of a glucose fuel cell is not new: In the 1970s, scientists showed they could power a pacemaker with a glucose fuel cell, but the idea was abandoned in favor of lithium-ion batteries, which could provide significantly more power per unit area than glucose fuel cells. These glucose fuel cells also utilized enzymes that proved to be impractical for long-term implantation in the body, since they eventually ceased to function efficiently.

The new twist to the MIT fuel cell described in PLoS ONE is that it is fabricated from silicon, using the same technology used to make semiconductor electronic chips. The fuel cell has no biological components: It consists of a platinum catalyst that strips electrons from glucose, mimicking the activity of cellular enzymes that break down glucose to generate ATP, the cell's energy currency. (Platinum has a proven record of long-term biocompatibility within the body.) So far, the fuel cell can generate up to hundreds of microwatts -- enough to power an ultra-low-power and clinically useful neural implant.

"It will be a few more years into the future before you see people with spinal-cord injuries receive such implantable systems in the context of standard medical care, but those are the sorts of devices you could envision powering from a glucose-based fuel cell," says Benjamin Rapoport, a former graduate student in the Sarpeshkar lab and the first author on the new MIT study.

Rapoport calculated that in theory, the glucose fuel cell could get all the sugar it needs from the cerebrospinal fluid (CSF) that bathes the brain and protects it from banging into the skull. There are very few cells in the CSF, so it's highly unlikely that an implant located there would provoke an immune response. There is also significant glucose in the CSF, which does not generally get used by the body. Since only a small fraction of the available power is utilized by the glucose fuel cell, the impact on the brain's function would likely be small.

Karim Oweiss, an associate professor of electrical engineering, computer science and neuroscience at Michigan State University, says the work is a good step toward developing implantable medical devices that don't require external power sources.

"It's a proof of concept that they can generate enough power to meet the requirements," says Oweiss, adding that the next step will be to demonstrate that it can work in a living animal.

A team of researchers at Brown University, Massachusetts General Hospital and other institutions recently demonstrated that paralyzed patients could use a brain-machine interface to move a robotic arm; those implants have to be plugged into a wall outlet.

Mimicking biology with microelectronics

Sarpeshkar's group is a leader in the field of ultra-low-power electronics, having pioneered such designs for cochlear implants and brain implants. "The glucose fuel cell, when combined with such ultra-low-power electronics, can enable brain implants or other implants to be completely self-powered," says Sarpeshkar, author of the book "Ultra Low Power Bioelectronics." This book discusses how the combination of ultra-low-power and energy-harvesting design can enable self-powered devices for medical, bio-inspired and portable applications.

Sarpeshkar's group has worked on all aspects of implantable brain-machine interfaces and neural prosthetics, including recording from nerves, stimulating nerves, decoding nerve signals and communicating wirelessly with implants. One such neural prosthetic is designed to record electrical activity from hundreds of neurons in the brain's motor cortex, which is responsible for controlling movement. That data is amplified and converted into a digital signal so that computers -- or in the Sarpeshkar team's work, brain-implanted microchips -- can analyze it and determine which patterns of brain activity produce movement.

The fabrication of the glucose fuel cell was done in collaboration with Jakub Kedzierski at MIT's Lincoln Laboratory. "This collaboration with Lincoln Lab helped make a long-term goal of mine -- to create glucose-powered bioelectronics -- a reality," Sarpeshkar says. Although he has just begun working on bringing ultra-low-power and medical technology to market, he cautions that glucose-powered implantable medical devices are still many years away.

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Leaping Lizards and Dinosaurs Inspire Robot Design

Leaping Lizards and Dinosaurs Inspire Robot Design

  10:48:00 PM    Science Lover

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Leaping lizards have a message for robots: Get a tail! University of California, Berkeley, biologists and engineers -- including undergraduate and graduate students -- studied how lizards manage to leap successfully even when they slip and stumble. They found that lizards swing their tails upward to prevent them from pitching head-over-heels into a rock.

An Agama lizard next to Tailbot, a toy car with an attached tail 
and a toy figure. Sensors detect Tailbot's orientation and swing 
the tail upward to keep the robot from pitching forward, similar 
to the way the lizard uses its tail. 
(Credit: Photo by Robert Full lab, UC Berkeley.)

But after the team added a tail to a robotic car named Tailbot, they discovered that counteracting the effect of a slip is not as simple as throwing your tail in the air. Instead, robots and lizards must actively adjust the angle of their tails just right to remain upright.

"We showed for the first time that lizards swing their tail up or down to counteract the rotation of their body, keeping them stable," said team leader Robert J. Full, UC Berkeley professor of integrative biology. "Inspiration from lizard tails will likely lead to far more agile search-and-rescue robots, as well as ones having greater capability to more rapidly detect chemical, biological or nuclear hazards."

Agile therapod dinosaurs like the velociraptor depicted in the movie Jurassic Park may also have used their tails as stabilizers to prevent forward pitch, Full said. Their tail movement is illustrated in a prescient chase sequence from the 1993 movie in which the animated animal leaps from a balcony onto a T. rex skeleton.

"Muscles willing, the dinosaur could be even more effective with a swing of its tail in controlling body attitude than the lizards," Full said.

Student involvement crucial to research

Full and his laboratory colleagues, including both engineering and biology students, will report their discoveries online on Jan. 5 in advance of publication in the Jan. 12 print edition of the journal Nature. The paper's first author, mechanical engineering graduate student Thomas Libby, also will report the results on Jan. 7 at the annual meeting of the Society for Integrative and Comparative Biology in Charleston, S.C.

Full is enthusiastic about the interplay fostered at UC Berkeley between biologists and engineers in the Center for Interdisciplinary Bio-inspiration in Education and Research (CiBER) lab, within which he offers a research-based teaching lab that provides dozens of undergraduate students with an opportunity to conduct cutting-edge research in teams with graduate students. Each team experiences the benefits of how biologists and engineers approach a problem.

"Learning in the context of original discovery, finding out something that no one has ever know before, really motivated me," said former UC Berkeley integrative biology undergraduate Talia Moore, now a graduate student in the Department of Organismic and Evolutionary Biology at Harvard University. "This research-based lab course … showed me how biologists and engineers can work together to benefit both fields."

"This paper shows that research-based teaching leads to better learning and simultaneously can lead to cutting-edge research," added Full, who last year briefed the U.S. House of Representative's Science, Technology, Engineering and Mathematics (STEM) Education Caucus on this topic. "It also shows the competitive advantage of interdisciplinary approaches and how involvement of undergraduates in research can lead to innovation."

From gecko toe hairs to tails

Full's research over the past 20 years has revealed how the toe hairs of geckos assist them in climbing smooth vertical surfaces and, more recently, how their tails help to keep them from falling when they slip and to right themselves in mid-air.

The new research tested a 40-year-old hypothesis that the two-legged theropod dinosaurs ‑ the ancestors of birds ‑ used their tails as stabilizers while running or dodging obstacles or predators. In Full's teaching laboratory, students noticed a lizard's recovery after slipping during a leap and thought a study of stumbling would be a perfect way to test the value of a tail.

In the CiBER lab, Full and six of his students used high-speed videography and motion capture to record how a red-headed African Agama lizard handled leaps from a platform with different degrees of traction, from slippery to easily-gripped.

They coaxed the lizards to run down a track, vault off a low platform and land on a vertical surface with a shelter on top. When the friction on the platform was reduced, lizards slipped, causing their bodies to potentially spin out of control.

When the researchers saw how the lizard used its tail to counteract the spin, they created a mathematical model as well as Tailbot -- a toy car equipped with a tail and small gyroscope to sense body position ‑ to better understand the animal's skills. With a tail but no feedback from sensors about body position, Tailbot took a nose dive when driven off a ramp, mimicking a lizard's take-off. When body position was sensed and fed back to the tail motor, however, Tailbot was able to stabilize its body in midair. The actively controlled tail effectively redirected the angular momentum of the body into the tail's swing, as happens with leaping lizards, Full said.

Inertial assisted robotics

Tailbot's design pushed the boundaries of control in robotics in an area researchers call inertial assisted robotics, an attention-grabber at last October's meeting of the International Conference on Intelligent Robots and Systems. The UC Berkeley researchers' paper, presented by Libby and fellow mechanical engineering graduate student Evan Chang-Siu, was one of five finalists there among more than 2,000 robot studies.

"Engineers quickly understood the value of a tail," Libby said, noting that when he dropped Tailbot nose-down, it was able to right itself before it had dropped a foot. "Robots are not nearly as agile as animals, so anything that can make a robot more stable is an advancement, which is why this work is so exciting."

Full and his students are now investigating the role of the tail in controlling pitch, roll and yaw while running.

UC Berkeley coauthors include Full and students Moore, Libby and Chang-Siu, along with Department of Integrative Biology undergraduate Deborah Li and graduate students Ardian Jusufi in the Department of Integrative Biology and Daniel Cohen in the Department of Bioengineering.

The work was funded by the National Science Foundation, including the NSF's Integrative Graduate Education and Research Traineeship (IGERT) program, and the Micro Autonomous Systems Technologies (MAST) consortium, a large group of researchers funded in part by the U.S. Army Research Laboratory that is focused on creating autonomous sensing robots.

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Novel Device Removes Heavy Metals from Water

Novel Device Removes Heavy Metals from Water

  9:33:00 AM    Science Lover

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Engineers at Brown University have developed a system that cleanly and efficiently removes trace heavy metals from water. In experiments, the researchers showed the system reduced cadmium, copper, and nickel concentrations, returning contaminated water to near or below federally acceptable standards. The technique is scalable and has viable commercial applications, especially in the environmental remediation and metal recovery fields.

Heavy metal removal Brown engineers have devised an
automated system that combines chemical precipitation
with electrolytic techniques in a cyclic fashion to remove
mixtures of trace heavy metals from contaminated water.
(Credit: Calo Lab/Brown University)

Results appear in the Chemical Engineering Journal.

An unfortunate consequence of many industrial and manufacturing practices, from textile factories to metalworking operations, is the release of heavy metals in waterways. Those metals can remain for decades, even centuries, in low but still dangerous concentrations.

Ridding water of trace metals "is really hard to do," said Joseph Calo, professor emeritus of engineering who maintains an active laboratory at Brown. He noted the cost, inefficiency, and time needed for such efforts. "It's like trying to put the genie back in the bottle."

That may be changing. Calo and other engineers at Brown describe a novel method that collates trace heavy metals in water by increasing their concentration so that a proven metal-removal technique can take over. In a series of experiments, the engineers report the method, called the cyclic electrowinning/precipitation (CEP) system, removes up to 99 percent of copper, cadmium, and nickel, returning the contaminated water to federally accepted standards of cleanliness. The automated CEP system is scalable as well, Calo said, so it has viable commercial potential, especially in the environmental remediation and metal recovery fields. The system's mechanics and results are described in a paper published in the Chemical Engineering Journal.

A proven technique for removing heavy metals from water is through the reduction of heavy metal ions from an electrolyte. While the technique has various names, such as electrowinning, electrolytic removal/recovery or electroextraction, it all works the same way, by using an electrical current to transform positively charged metal ions (cations) into a stable, solid state where they can be easily separated from the water and removed. The main drawback to this technique is that there must be a high-enough concentration of metal cations in the water for it to be effective; if the cation concentration is too low -- roughly less than 100 parts per million -- the current efficiency becomes too low and the current acts on more than the heavy metal ions.

Another way to remove metals is through simple chemistry. The technique involves using hydroxides and sulfides to precipitate the metal ions from the water, so they form solids. The solids, however, constitute a toxic sludge, and there is no good way to deal with it. Landfills generally won't take it, and letting it sit in settling ponds is toxic and environmentally unsound. "Nobody wants it, because it's a huge liability," Calo said.

The dilemma, then, is how to remove the metals efficiently without creating an unhealthy byproduct. Calo and his co-authors, postdoctoral researcher Pengpeng Grimshaw and George Hradil, who earned his doctorate at Brown and is now an adjunct professor, combined the two techniques to form a closed-loop system. "We said, 'Let's use the attractive features of both methods by combining them in a cyclic process,'" Calo said.

It took a few years to build and develop the system. In the paper, the authors describe how it works. The CEP system involves two main units, one to concentrate the cations and another to turn them into stable, solid-state metals and remove them. In the first stage, the metal-laden water is fed into a tank in which an acid (sulfuric acid) or base (sodium hydroxide) is added to change the water's pH, effectively separating the water molecules from the metal precipitate, which settles at the bottom. The "clear" water is siphoned off, and more contaminated water is brought in. The pH swing is applied again, first redissolving the precipitate and then reprecipitating all the metal, increasing the metal concentration each time. This process is repeated until the concentration of the metal cations in the solution has reached a point at which electrowinning can be efficiently employed.

When that point is reached, the solution is sent to a second device, called a spouted particulate electrode (SPE). This is where the electrowinning takes place, and the metal cations are chemically changed to stable metal solids so they can be easily removed. The engineers used an SPE developed by Hradil, a senior research engineer at Technic Inc., located in Cranston, R.I. The cleaner water is returned to the precipitation tank, where metal ions can be precipitated once again. Further cleaned, the supernatant water is sent to another reservoir, where additional processes may be employed to further lower the metal ion concentration levels. These processes can be repeated in an automated, cyclic fashion as many times as necessary to achieve the desired performance, such as to federal drinking water standards.

In experiments, the engineers tested the CEP system with cadmium, copper, and nickel, individually and with water containing all three metals. The results showed cadmium, copper, and nickel were lowered to 1.50, 0.23 and 0.37 parts per million (ppm), respectively -- near or below maximum contaminant levels established by the Environmental Protection Agency. The sludge is continuously formed and redissolved within the system so that none is left as an environmental contaminant.

"This approach produces very large volume reductions from the original contaminated water by electrochemical reduction of the ions to zero-valent metal on the surfaces of the cathodic particles," the authors write. "For an initial 10 ppm ion concentration of the metals considered, the volume reduction is on the order of 106."

Calo said the approach can be used for other heavy metals, such as lead, mercury, and tin. The researchers are currently testing the system with samples contaminated with heavy metals and other substances, such as sediment, to confirm its operation.

The research was funded by the National Institute of Environmental Health Sciences, a branch of the National Institutes of Health, through the Brown University Superfund Research Program.

Editors: Brown University has a fiber link television studio available for domestic and international live and taped interviews, and maintains an ISDN line for radio interviews. For more information, call (401) 863-2476.

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Better Batteries: New Technology Improves Both Energy Capacity and Charge Rate in Rechargeable Batteries

Better Batteries: New Technology Improves Both Energy Capacity and Charge Rate in Rechargeable Batteries

  8:37:00 PM    Science Lover

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Imagine a cellphone battery that stayed charged for more than a week and recharged in just 15 minutes. That dream battery could be closer to reality thanks to Northwestern University research.

New research could lead to rechargeable lithium-ion
batteries that hold a charge up to 10 times greater than
current technology and that charge 10 times faster than
current batteries. (Credit: © janaka Dharmasena / Fotolia)

A team of engineers has created an electrode for lithium-ion batteries -- rechargeable batteries such as those found in cellphones and iPods -- that allows the batteries to hold a charge up to 10 times greater than current technology. Batteries with the new electrode also can charge 10 times faster than current batteries.

The researchers combined two chemical engineering approaches to address two major battery limitations -- energy capacity and charge rate -- in one fell swoop. In addition to better batteries for cellphones and iPods, the technology could pave the way for more efficient, smaller batteries for electric cars.

The technology could be seen in the marketplace in the next three to five years, the researchers said.

A paper describing the research is published by the journal Advanced Energy Materials.

"We have found a way to extend a new lithium-ion battery's charge life by 10 times," said Harold H. Kung, lead author of the paper. "Even after 150 charges, which would be one year or more of operation, the battery is still five times more effective than lithium-ion batteries on the market today."

Kung is professor of chemical and biological engineering in the McCormick School of Engineering and Applied Science. He also is a Dorothy Ann and Clarence L. Ver Steeg Distinguished Research Fellow.

Lithium-ion batteries charge through a chemical reaction in which lithium ions are sent between two ends of the battery, the anode and the cathode. As energy in the battery is used, the lithium ions travel from the anode, through the electrolyte, and to the cathode; as the battery is recharged, they travel in the reverse direction.

With current technology, the performance of a lithium-ion battery is limited in two ways. Its energy capacity -- how long a battery can maintain its charge -- is limited by the charge density, or how many lithium ions can be packed into the anode or cathode. Meanwhile, a battery's charge rate -- the speed at which it recharges -- is limited by another factor: the speed at which the lithium ions can make their way from the electrolyte into the anode.

In current rechargeable batteries, the anode -- made of layer upon layer of carbon-based graphene sheets -- can only accommodate one lithium atom for every six carbon atoms. To increase energy capacity, scientists have previously experimented with replacing the carbon with silicon, as silicon can accommodate much more lithium: four lithium atoms for every silicon atom. However, silicon expands and contracts dramatically in the charging process, causing fragmentation and losing its charge capacity rapidly.

Currently, the speed of a battery's charge rate is hindered by the shape of the graphene sheets: they are extremely thin -- just one carbon atom thick -- but by comparison, very long. During the charging process, a lithium ion must travel all the way to the outer edges of the graphene sheet before entering and coming to rest between the sheets. And because it takes so long for lithium to travel to the middle of the graphene sheet, a sort of ionic traffic jam occurs around the edges of the material.

Now, Kung's research team has combined two techniques to combat both these problems. First, to stabilize the silicon in order to maintain maximum charge capacity, they sandwiched clusters of silicon between the graphene sheets. This allowed for a greater number of lithium atoms in the electrode while utilizing the flexibility of graphene sheets to accommodate the volume changes of silicon during use.

"Now we almost have the best of both worlds," Kung said. "We have much higher energy density because of the silicon, and the sandwiching reduces the capacity loss caused by the silicon expanding and contracting. Even if the silicon clusters break up, the silicon won't be lost."

Kung's team also used a chemical oxidation process to create miniscule holes (10 to 20 nanometers) in the graphene sheets -- termed "in-plane defects" -- so the lithium ions would have a "shortcut" into the anode and be stored there by reaction with silicon. This reduced the time it takes the battery to recharge by up to 10 times.

This research was all focused on the anode; next, the researchers will begin studying changes in the cathode that could further increase effectiveness of the batteries. They also will look into developing an electrolyte system that will allow the battery to automatically and reversibly shut off at high temperatures -- a safety mechanism that could prove vital in electric car applications.

The Energy Frontier Research Center program of the U.S. Department of Energy, Basic Energy Sciences, supported the research.

The paper is titled "In-Plane Vacancy-Enabled High-Power Si-Graphene Composite Electrode for Lithium-Ion Batteries." Other authors of the paper are Xin Zhao, Cary M. Hayner and Mayfair C. Kung, all from Northwestern.

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Electricity from the nose: Engineers make power from human respiration

Electricity from the nose: Engineers make power from human respiration

  8:59:00 AM    Science Lover

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The same piezoelectric effect that ignites your gas grill with the push of a button could one day power sensors in your body via the respiration in your nose.

Graduate Student Jian Shi and Materials Science and
Engineering Assistant Professor Xudong Wang
demonstrate a material that could be used to
capture energy from respiration.

Writing in the September issue of the journal Energy and Environmental Science, Materials Science and Engineering Assistant Professor Xudong Wang, postdoctoral Researcher Chengliang Sun and graduate student Jian Shi report creating a plastic microbelt that vibrates when passed by low-speed airflow such as human respiration.

In certain materials, such as the polyvinylidene fluoride (PVDF) used by Wang’s team, an electric charge accumulates in response to applied mechanical stress. This is known as the piezoelectric effect. The researchers engineered PVDF to generate sufficient electrical energy from respiration to operate small electronic devices.



“Basically, we are harvesting mechanical energy from biological systems. The airflow of normal human respiration is typically below about two meters per second,” says Wang. “We calculated that if we could make this material thin enough, small vibrations could produce a microwatt of electrical energy that could be useful for sensors or other devices implanted in the face.”

Researchers are taking advantage of advances in nanotechnology and miniaturized electronics to develop a host of biomedical devices that could monitor blood glucose for diabetics or keep a pacemaker battery charged so that it would not need replacing. What’s needed to run these tiny devices is a miniscule power supply. Waste energy in the form or blood flow, motion, heat, or in this case respiration, offers a consistent source of power.

Wang’s team used an ion-etching process to carefully thin material while preserving its piezoelectric properties. With improvements, he believes the thickness can be controlled down to the submicron level. Because PVDF is biocompatible, he says the development represents a significant advance toward creating a practical micro-scale device for harvesting energy from respiration.

Provided by University of Wisconsin-Madison

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Deep Brain Stimulation Studies Show How Brain Buys Time for Tough Choices

Deep Brain Stimulation Studies Show How Brain Buys Time for Tough Choices

  8:22:00 PM    Science Lover

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Take your time. Hold your horses. Sleep on it. When people must decide between arguably equal choices, they need time to deliberate. In the case of people undergoing deep brain stimulation (DBS) for Parkinson's disease, that process sometimes doesn't kick in, leading to impulsive behavior. Some people who receive deep brain stimulation for Parkinson's disease behave impulsively, making quick, often bad, decisions.

Red is for reflection. The hotter the color, especially in the circled area, the more likely the brain was to take its time making difficult decisions. Parkinson's patients whose deep brain stimulators were on (right), were more impulsive -- a cooler blue. (Credit: Frank Lab/Brown University)

New research into why that happens has led scientists to a detailed explanation of how the brain devotes time to reflect on tough choices.

Michael Frank, professor of cognitive, linguistic, and psychological sciences at Brown University, studied the impulsive behavior of Parkinson's patients when he was at the University of Arizona several years ago. His goal was to model the brain's decision-making mechanics. He had begun working with Parkinson's patients because DBS, a treatment that suppresses their tremor symptoms, delivers pulses of electrical current to the subthalamic nucleus (STN), a part of the brain that Frank hypothesized had an important role in decisions. Could the STN be what slams the brakes on impulses, giving the medial prefrontal cortex (mPFC) time to think?

When the medial prefrontal cortex needs time to deliberate, it recruits help in warding off impulsive urges from elsewhere in the brain."We didn't have any direct evidence of that," said Frank, who is affiliated with the Brown Institute for Brain Science. "To test that theory for how areas of the brain interact to prevent you from making impulsive decisions and how that could be changed by DBS, you have to do experiments where you record brain activity in both parts of the network that we think are involved. Then you also have to manipulate the system to see how the relationship between recorded activity in one area and decision making changes as a function of stimulating the other area."

Frank and his team at Brown and Arizona did exactly that. They describe their findings in a study published online in the journal Nature Neuroscience.

The researchers' measurements from two experiments and analysis with a computer model support the theory that when the mPFC is faced with a tough decision, it recruits the STN to ward off more impulsive urges coming from the striatum, a third part of the brain. That allows it time to make its decision.

For their first experiment, the researchers designed a computerized decision-making experiment. They asked 65 healthy subjects and 14 subjects with Parkinson's disease to choose between pairs of generic line art images while their mPFC brain activity was recorded. Each image was each associated with a level of reward. Over time the subjects learned which ones carried a greater reward.

Sometimes, however, the subjects would be confronted with images of almost equal reward -- a relatively tough choice. That's when scalp electrodes detected elevated activity in the mPFC in certain low frequency bands. Lead author and postdoctoral scholar James Cavanagh found that when mPFC activity was larger, healthy participants and Parkinson's participants whose stimulators were off would take proportionally longer to decide. But when deep brain stimulators were turned on to alter STN function, the relationship between mPFC activity and decision making was reversed, leading to decision making that was quicker and less accurate.



The Parkinson's patients whose stimulators were on still showed the same elevated level of activity in the mPFC. The cortex wanted to deliberate, Cavanagh said, but the link to the brakes had been cut.

"Parkinson's patients on DBS had the same signals," he said. "It just didn't relate to behavior. We had knocked out the network."

In the second experiment, the researchers presented eight patients with the same decision-making game while they were on the operating table in Arizona receiving their DBS implant. The researchers used the electrode to record activity directly in the STN and found a pattern of brain activity closely associated with the patterns they observed in the mPFC.

"The STN has greater activity with greater [decision] conflict," he said. "It is responsive to the circumstances that the signals on top of the scalp are responsive to, and in highly similar frequency bands and time ranges."

A mathematical model for analyzing the measurements of accuracy and response time confirmed that the elevated neural activity and the extra time people took to decide was indeed evidence of effortful deliberation.

"It was not that they were waiting without doing anything," said graduate student Thomas Wiecki, the paper's second author. "They were slower because they were taking the time to make a more informed decision. They were processing it more thoroughly."

The results have led the researchers to think that perhaps the different brain regions communicate by virtue of these low-frequency signals. Maybe the impulsivity side effect of DBS could be mitigated if those bands could remain unhindered by the stimulator's signal. Alternatively, Wiecki said, a more sophisticated DBS system could sense that decision conflict is underway in the mPFC and either temporarily suspend its operation until the decision is made, or stimulate the STN in a more dynamic way to better mimic intact STN function.

These are not trivial ideas to foist upon DBS engineers, but by understanding the mechanics underlying the side effect -- and in healthy unhindered decision making -- the researchers say they now have a target to consider.

In addition to Frank, Cavanagh, and Wiecki, another Brown author is Christina Figueroa. Arizona authors include Michael Cohen, Johan Samanta, and Scott Sherman.

The Michael J. Fox Foundation funded the research.

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World-Record Pulsed Magnetic Field Achieved; Lab Moves Closer to 100-Tesla Mark

World-Record Pulsed Magnetic Field Achieved; Lab Moves Closer to 100-Tesla Mark

  10:14:00 AM    Science Lover

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Researchers at the National High Magnetic Field Laboratory's Pulsed Field Facility at Los Alamos National Laboratory have set a new world record for the strongest magnetic field produced by a nondestructive magnet.

Yates Coulter, left, and Mike Gordon of Los Alamos National Laboratory make final preparations before successfully achieving a world-record for the strongest magnetic field produced by a nondestructive magnet. Working at the National High Magnetic Field Laboratory's Pulsed Field Facility at Los Alamos, a team of researchers achieved a field of 97.4 tesla, which is nearly 100 times stronger than the magnetic field found in giant electromagnets used in metal scrap yards. (Credit: Image courtesy of DOE/Los Alamos National Laboratory)

The scientists achieved a field of 92.5 tesla on Thursday, August 18, taking back a record that had been held by a team of German scientists and then, the following day, surpassed their achievement with a whopping 97.4-tesla field. For perspective, Earth's magnetic field is 0.0004 tesla, while a junk-yard magnet is 1 tesla and a medical MRI scan has a magnetic field of 3 tesla.

The ability to create pulses of extremely high magnetic fields nondestructively (high-power magnets routinely rip themselves to pieces due to the large forces involved) provides researchers with an unprecedented tool for studying fundamental properties of materials, from metals and superconductors to semiconductors and insulators. The interaction of high magnetic fields with electrons within these materials provides valuable clues for scientists about the properties of materials. With the recent record-breaking achievement, the Pulsed Field Facility at LANL, a national user facility, will routinely provide scientists with magnetic pulses of 95 tesla, enticing the worldwide user community to Los Alamos for a chance to use this one-of-a-kind capability.

The record puts the Los Alamos team within reach of delivering a magnet capable of achieving 100 tesla, a goal long sought by researchers from around the world, including scientists working at competing magnet labs in Germany, China, France, and Japan.

Such a powerful nondestructive magnet could have a profound impact on a wide range of scientific investigations, from how to design and control material functionality to research into the microscopic behavior of phase transitions. This type of magnet allows researchers to carefully tune material parameters while perfectly reproducing the non-invasive magnetic field. Such high magnetic fields confine electrons to nanometer scale orbits, thereby helping to reveal the fundamental quantum nature of a material.



Thursday's experiment was met with as much excitement as trepidation by the group of condensed matter scientists, high-field magnet technicians, technologists, and pulsed-magnet engineers who gathered to witness the NHMFL-PFF retake the world record. Crammed into the tight confines of the Magnet Lab's control room, they gathered, lab notebooks or caffeine of choice in hand. Their conversation reflected a giddy sense of anticipation tempered with nervousness.

With Mike Gordon commanding the controls that draw power off of a massive 1.4-gigawatt generator system and directs it to the magnet, all eyes and ears were keyed to video monitors showing the massive 100 tesla Multishot Magnet and the capacitor bank located in the now eerily empty Large Magnet Hall next door. The building had been emptied as a standard safety protocol.

Scientists heard a low warping hum, followed by a spine-tingling metallic screech signaling that the magnet was spiking with a precisely distributed electric current of more than 100 megajoules of energy. As the sound dissipated and the monitors confirmed that the magnet performed perfectly, attention turned to data acquired during the shot through two in-situ measurements -- proof positive that the magnet had achieved 92.5 tesla, thus yanking back from a team of German scientists a record that Los Alamos had previously held for five years.

The next day's even higher 97.4-tesla achievement was met with high-fives and congratulatory pats on the back. Later, researchers Charles Mielke, Neil Harrison, Susan Seestrom, and Albert Migliori certified with their signatures the data that would be sent to the Guiness Book of World Records.

The NHMFL is sponsored primarily by the National Science Foundation, Division of Materials Research, with additional support from the State of Florida and the DOE. These recent successes were enabled by long-term support from the U.S. Department of Energy's Office of Basic Energy Sciences, and the National Science Foundation's 100 Tesla Multi-Shot magnet program.

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Engineers Reverse E. Coli Metabolism for Quick Production of Fuels, Chemicals

Engineers Reverse E. Coli Metabolism for Quick Production of Fuels, Chemicals

  10:54:00 PM    Science Lover

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In a biotechnological tour de force, Rice University engineering researchers this week unveiled a new method for rapidly converting simple glucose into biofuels and petrochemical substitutes. In a paper published online in Nature, Rice's team described how it reversed one of the most efficient of all metabolic pathways -- the beta oxidation cycle -- to engineer bacteria that produce biofuel at a breakneck pace.

Rice University engineering researchers Ramon Gonzalez (left) and
Clementina Dellomonaco reversed one of the most efficient of all
metabolic pathways -- the beta oxidation cycle -- to engineer bacteria
that make biofuels at a breakneck pace. (Credit: Jeff Fitlow/Rice
University)

Just how fast are Rice's single-celled chemical factories? On a cell-per-cell basis, the bacteria produced the butanol, a biofuel that can be substituted for gasoline in most engines, about 10 times faster than any previously reported organism.


"That's really not even a fair comparison because the other organisms used an expensive, enriched feedstock, and we used the cheapest thing you can imagine, just glucose and mineral salts," said Ramon Gonzalez, associate professor of chemical and biomolecular engineering at Rice and lead co-author of the Nature study.


Gonzalez's laboratory is in a race with hundreds of labs around the world to find green methods for producing chemicals like butanol that have historically come from petroleum.


"We call these 'drop-in' fuels and chemicals, because their structure and properties are very similar, sometimes identical, to petroleum-based products," he said. "That means they can be 'dropped in,' or substituted, for products that are produced today by the petrochemical industry."




Butanol is a relatively short molecule, with a backbone of just four carbon atoms. Molecules with longer carbon chains have been even more troublesome for biotech producers to make, particularly molecules with chains of 10 or more carbon atoms. Gonzalez said that's partly because researchers have focused on ramping up the natural metabolic processes that cells use to build long-chain fatty acids. Gonzalez and students Clementina Dellomonaco, James Clomburg and Elliot Miller took a completely different approach.


"Rather than going with the process nature uses to build fatty acids, we reversed the process that it uses to break them apart," Gonzalez said. "It's definitely unconventional, but it makes sense because the routes nature has selected to build fatty acids are very inefficient compared with the reversal of the route it uses to break them apart."


The beta oxidation process is one of biology's most fundamental, Gonzalez said. Species ranging from single-celled bacteria to human beings use beta oxidation to break down fatty acids and generate energy.


In the Nature study, Gonzalez's team reversed the beta oxidation cycle by selectively manipulating about a dozen genes in the bacteria Escherichia coli. They also showed that selective manipulations of particular genes could be used to produce fatty acids of particular lengths, including long-chain molecules like stearic acid and palmitic acid, which have chains of more than a dozen carbon atoms.


"This is not a one-trick pony," Gonzalez said. "We can make many kinds of specialized molecules for many different markets. We can also do this in any organism. Some producers prefer to use industrial organisms other than E. coli, like algae or yeast. That's another advantage of using reverse-beta oxidation, because the pathway is present in almost every organism."


The research was funded by Rice University.

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