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This method could pave the way for cheaper next-generation thin-film and flexible electronics. The work, which describes the results for films of several different compositions, appeared on Sunday in the journal Nature Materials.

The thin-film electronics behind today’s flat-panel displays are made of chaotically structured, or amorphous, silicon. But amorphous silicon is reaching its performance limits, and a new class of materials—amorphous oxides— will soon be making its commercial debut. Electrons in amorphous oxides can zoom through the material dozens of times as fast as they do in amorphous silicon, making for faster electronics. And unlike amorphous silicon, oxides carry current the same way in every direction, making them better candidates for bendable electronics like flexible solar arrays and roll-up displays.

To make these thin films, engineers primarily rely on ”sputtering,” in which vaporized material is flung at its target inside a vacuum chamber. This process would potentially be less costly if the material could be applied as a solution instead. But fans of the solution-based method have had to confront some inconvenient physics. Heat must be applied to condense the metal oxide, and the material performs best after it has been heated above 300 °C, which is about 100 degrees too hot for most flexible plastics.

Now Mercouri Kanatazidis, Tobin Marks, Antonio Facchetti, and Myung-Gil Kim of Northwestern University, in Evanston, Ill., think they’ve come up with a fix: replacing the external heat of an oven with the internal heat of a chemical reaction.

Many thin-film metal oxide solutions are made using water and metal-containing salts. When the temperature rises high enough, the oxygen atoms bind with the metal to form a chaotic tangle of metal-oxygen bonds. The team found that if they included a fuel like acetylacetone or urea in the mix, they could raise the internal energy of the mixture. Boosting the temperature to just 200 °C triggered a combustion reaction and enough self-generated heat to anneal metal-oxide films.

One of the team’s biggest challenges was finding a way to deal with structural changes created through the combustion process. The internal heat can create voids in the resulting films. These voids are useful for sensors and catalysts that require a lot of surface area, says team member Facchetti, who is also affiliated with Polyera Corp., in Skokie, Ill. But the gaps are counterproductive for thin-film electronics because they reduce the overlap between the atoms’ electron clouds and thus hinder the ability to transport current. ”One of the major challenges was to make sure we could make a film that is very dense,” Facchetti says. The team ultimately found it could circumvent the void problem by alternately depositing and annealing thin layers to build up the film.

One device made using the technique—an indium oxide transistor—boasted an electron mobility of 6 square centimeters per volt second, roughly 10 times that of thin-film amorphous silicon devices. That’s a heartening figure but one that will have to be backed up with more experiments, says John Wager of Oregon State University, in Corvallis, Ore. ”If the extra energy from combustion-based synthesis really does give you better-performing devices at low temperature, then that’s really nice,” Wager says. (See the feature article by John Wager and Randy Hoffman in the May 2011 issue of IEEE Spectrum for more on amorphous oxide semiconductors.)

One big question that will need to be answered in future work, Wager says, is how stable these devices can be. The threshold voltage needed to turn on thin-film transistors tends to drift with use, and that behavior ”tends to be more problematic at low temperature,” he says. ”If their combustion synthesis leads to more stable transistors, that could be really big.”

Source: spectrum

 

Spintronics — also known as magnetoelectronics — may replace electronics as the medium of choice for computer memory. The discovery of a mechanism that produces permanent magnets at room temperature, without any external influence, may soon improve the design of spintronic devices. Takumi Ohtsuki from the RIKEN SPring-8 Center, Harima and his colleagues in Japan, made the discovery in a class of material called a dilute ferromagnetic oxide.

Mediating magnetism

A representation of a thin film of Co:TiO2 in which ferromagnetism arises because titanium 3d electrons (green) travel around the material aligning the spin of cobalt atoms (pink) so that they all point in the same direction. The blue and brown spheres correspond to titanium and oxygen atoms, respectively. Credit: 2011 Takumi Ohtsuki

Ferromagnetism is the mechanism responsible for making some materials magnetic without any external influence. In a ferromagnet, the axes about which a majority of the electrons spin are all parallel, but the underlying cause for this alignment is not always clear. A dilute ferromagnetic oxide is an oxide material doped with a small amount of a transition metal, which represents a marriage between magnetic materials and those used in electronics. Crucially, and unlike the ferromagnetic-semiconductors, dilute ferromagnetic oxides remain in a ferromagnetic state at room temperature.

Some materials have ferromagnetic constituents but exhibit no magnetism. However, some ferromagnets consist of substances that, on their own, are nonmagnetic. A full understanding of this enigma is vital for designing efficient spintronic devices and requires determining which electrons, or other type of charge carrier in a material, mediate the ferromagnetism. To resolve this question in dilute ferromagnetic oxides, Ohtsuki and his co-workers examined one commonly used example: cobalt-doped titanium dioxide (Co:TiO2). “Several mechanisms have been suggested for the origin of ferromagnetism in Co:TiO2, but no firm conclusion has been established,” says Ohtsuki.

The researchers used a powerful material characterization technique known as x-ray photoemission spectroscopy. A beam of x-rays, in this case from the SPring-8 synchrotron radiation facility, excited electrons from the sample of Co:TiO2. “The number of excited electrons versus their kinetic energies provided detailed information about the atomic composition and electronic state of the material,” explains Ohtsuki.

Ohtsuki and his team established that ferromagnetism is mediated by the electrons in the third shell—so-called 3d electrons—of the titanium ions (Fig. 1), a mechanism that has never been considered as a possibility by scientists before. The titanium 3d electrons align the spin of the cobalt atoms as they travel through the material.

The team’s discovery enhances the likelihood that dilute ferromagnetic oxides will be used as spintronic devices. “Our results have proven that magnetism and conductivity are correlated in Co:TiO2 thin films,” explains Ohtsuki. “This could make them applicable to magnetic random access memory (MRAM) or spin transistors.”

Source: PhysOrg

 

Next-generation soap!

Waterborne disease kills three children every minute. This handheld device, called Kopper – which costs only $A2.50 to make – could prevent some of these deaths.

Designed by Balin Lee, a graduate of the University of Western Sydney, it removes 99.99 per cent of all parasites, viruses and bacteria found in contaminated water.

The device works by squeezing water through a microfilter, removing anything larger than 0.1 micrometre, which includes Escherichia coli and Giardia. It then fries anything left with electrolysis, which splits the oxygen and hydrogen molecules, removing tinier pathogens in the water.

Kopper is powered by piezoelectric generators that convert kinetic energy into an electrical current: powering the device requires only a few shakes.

(Image: Balin Lee/SRD Change)

Slum reshaping, breathing buildings and next-generation soap are just some of the ideas on display at the annual SRD Change Exhibition in Sydney, Australia. The show flaunts the best in sustainable and environmental design aiming "to create products and services that focus on tangible and positive benefits for society in every possible aspect", says Greg Campbell, the SRD Change curator.

Source: NewScientist.com

 

In a presentation during the 3rd Annual La Jolla Research & Innovation Summit this week, Norman said that the amount of digital data generated just by instruments such as DNA sequencers, cameras, telescopes, and MRIs is now doubling every 18 months.

“Digital data is advancing at least as fast, and probably faster, than Moore’s Law,” said Norman, referring to the computing hardware belief that the number of transistors which can be placed inexpensively on an integrated circuit doubles approximately every 18 months. “But I/O (input/output) transfer rates are not keeping pace – that is what SDSC’s supercomputers are designed to solve.”

Norman

SDSC, a key resource for UCSD researchers as well as the UC system and nationally, will later this year deploy a new data-intensive supercomputer system named Gordon, which will be the first high-performance supercomputer to use large amounts of flash-based SSD (solid state drive) memory. Flash memory is more common in smaller devices such as mobile phones and laptop computers, but unique for supercomputers, which generally use slower spinning disk technology.

The result of a five-year, $20 million grant from the National Science Foundation, Gordon will have 250 trillion bytes of flash memory and 64 I/O nodes, and be capable of handling massive data bases while providing up to 100 times faster speeds when compared to hard drive disk systems for some queries.

“We are re-engineering the entire data infrastructure in SDSC to support the capabilities offered by Gordon,” Norman said.

This makes Gordon ideal for data mining and data exploration, where researchers have to churn through tremendous amounts of data just to find a small amount of valuable information, not unlike a web search.

“Gordon is a supercomputer that will do for scientific data analysis what Google does for web search,” Norman told the summit, adding that SDSC likes to call the new system “the largest thumbdrive in the world.”

SDSC researchers are already doing preliminary tests on several potential applications using 16 I/O nodes of the Gordon system now in operation. Such data mining applications include ‘de novo,’ or ‘from the beginning’ genome assembly from sequencer reads, or classification of objects found in massive astronomical surveys.

“The future of personalized genomic medicine will require technologies like those prototyped in Gordon,” Norman said.

The new supercomputer also is expected to aid researchers in conducting interaction network analysis for new drug discovery. Other data-intensive computational science that will benefit from Gordon’s unique configuration include the solution of inverse problems – or converting observed measurements into information about a physical object or system – in oceanography, atmospheric science, and oil exploration, as well as using the system’s large shared memory system to research modestly scalable codes in quantum chemistry, structural engineering, and computer-aided design/computer-aided manufacturing (CAD/CAM) applications.

Earlier this year, SDSC deployed a new high-performance computer called Trestles, the result of a $2.8 million award from the NSF. Trestles is appropriately named because it will serve as a bridge between SDSC’s unique, data-intensive resources available to a wide community of users both now and into the future.

“These new systems were designed with one goal in mind, and that is to enable as much productive science as possible as we enter a data-intensive era of computing,” said Norman.

The annual La Jolla Research & Innovation Summit is organized by CONNECT, a San Diego-based group that links inventors and entrepreneurs with resources needed for commercialization by promoting collaborations between industry, venture capital sources, and research organizations including academic institutions such as UCSD.

Source: UC San Diego

 
By Admin (from 15/08/2011 @ 15:00:34, in en - Science and Society, read 1799 times)

A federal appeals court in Atlanta ruled Friday that a provision in President Obama's health care law requiring citizens to buy health insurance is unconstitutional, but the court didn't strike down the rest of the law.

The decision is a major setback for the White House, which had appealed a ruling by a lower court judge who struck down the entire law in January. But given that another appeals court, in Cincinnati, has upheld the law, it is increasingly clear that the Supreme Court will have the final say.

"We strongly disagree with this decision and we are confident it will not stand," White House spokeswoman Stephanie Cutter said in a statement.

On Friday, the divided three-judge panel of the 11th Circuit Court of Appeals sided with 26 states that filed a lawsuit to block Obama's signature domestic initiative. The panel said that Congress exceeded its constitutional authority by requiring Americans to buy insurance or face penalties.

"This economic mandate represents a wholly novel and potentially unbounded assertion of congressional authority," the panel said in the majority opinion.

The majority also said that a basic objective of the law is to "make health insurance coverage accessible and thereby to reduce the number of uninsured persons." Without the individual mandate, the majority said, the law "retains many other provisions that help to accomplish some of the same objectives as the individual mandate."

The decision is a review of a sweeping ruling by a Florida judge, who not only struck down a requirement that nearly all Americans carry health insurance, but he also threw out other provisions ranging from Medicare discounts for some seniors to a change that allows adult children up to age 26 to remain on their parents' coverage.

The states urged the 11th Circuit to uphold U.S. District Judge Roger Vinson's ruling, saying in a court filing that letting the law stand would set a troubling precedent that "would imperil individual liberty, render Congress's other enumerated powers superfluous, and allow Congress to usurp the general police power reserved to the states."

The Justice Department countered that Congress had the power to require most people to buy health insurance or face tax penalties because Congress has the authority to regulate interstate business. It said the legislative branch was exercising its "quintessential" rights when it adopted the new law.

During oral arguments in June, the three-judge panel repeatedly raised questions about the overhaul and expressed unease with the insurance requirement. Each of the three worried aloud if upholding the landmark law could open the door to Congress adopting other sweeping economic mandates.

The arguments unfolded in what's considered one of the nation's most conservative appeals courts. But the randomly selected panel represents different judicial perspectives. None of the three is considered either a stalwart conservative or an unfaltering liberal.

The National Federation of Independent Business (NFIB), the only private group to join the 26 states in the lawsuit, cheered the decision.

"Small-business owners across the country have been vindicated by the 11th Circuit's ruling that the individual mandate in the health-care law is unconstitutional," said Karen Harned, executive director of the group's legal center.

"The court reaffirmed what small businesses already knew - there are limits to Congress' power. And the individual mandate, which compels every American to buy health insurance or pay a fine, is a bridge too far," she said.

Source: foxnews.com - The Associated Press contributed to this report.

 

Automakers are now one step closer to being able to replace this long-standing technology with laser igniters, which will enable cleaner, more efficient, and more economical vehicles.

In the past, lasers strong enough to ignite an engine's air-fuel mixtures were too large to fit under an automobile's hood. At this year's Conference on Lasers and Electro Optics (CLEO: 2011), to be held in Baltimore May 1 - 6, researchers from Japan will describe the first multibeam laser system small enough to screw into an engine's cylinder head.

Equally significant, the new laser system is made from ceramics, and could be produced inexpensively in large volumes, according to one of the presentation's authors, Takunori Taira of Japan's National Institutes of Natural Sciences.

According to Taira, conventional spark plugs pose a barrier to improving fuel economy and reducing emissions of nitrogen oxidessmog. (NOx), a key component of

Spark plugs work by sending small, high-voltage electrical sparks across a gap between two metal electrodes. The spark ignites the air-fuel mixture in the engine's cylinder—producing a controlled explosion that forces the piston down to the bottom of the cylinder, generating the horsepower needed to move the vehicle.

Engines make NOx as a byproduct of combustion. If engines ran leaner – burnt more air and less fuel – they would produce significantly smaller NOx emissions.

Spark plugs can ignite cleaner fuel mixtures, but only by increasing spark energy. Unfortunately, these high voltages erode spark plug electrodes so fast, the solution is not economical. By contrast, lasers, which ignite the air-fuel mixture with concentrated optical energy, have no electrodes and are not affected.

Lasers also improve efficiency. Conventional spark plugs sit on top of the cylinder and only ignite the air-fuel mixture close to them. The relatively cold metal of nearby electrodes and cylinder walls absorbs heat from the explosion, quenching the flame front just as it starts to expand.

Lasers, Taira explains, can focus their beams directly into the center of the mixture. Without quenching, the flame front expands more symmetrically and up to three times faster than those produced by spark plugs.

Equally important, he says, lasers inject their energy within nanoseconds, compared with milliseconds for spark plugs. "Timing – quick combustion – is very important. The more precise the timing, the more efficient the combustion and the better the fuel economy," he says.

Lasers promise less pollution and greater fuel efficiency, but making small, powerful lasers has, until now, proven hard. To ignite combustion, a laser must focus light to approximately 100 gigawatts per square centimeter with short pulses of more than 10 millijoules each.

"In the past, lasers that could meet those requirements were limited to basic research because they were big, inefficient, and unstable," Taira says. Nor could they be located away from the engine, because their powerful beams would destroy any optical fibers that delivered light to the cylinders.

Taira's research team overcame this problem by making composite lasers from ceramic powders. The team heats the powders to fuse them into optically transparent solids and embeds metal ions in them to tune their properties.

Ceramics are easier to tune optically than conventional crystals. They are also much stronger, more durable, and thermally conductive, so they can dissipate the heat from an engine without breaking down.

Taira's team built its laser from two yttrium-aluminum-gallium (YAG) segments, one doped with neodymium, the other with chromium. They bonded the two sections together to form a powerful laser only 9 millimeters in diameter and 11 millimeters long (a bit less than half an inch).

The composite generates two laser beams that can ignite fuel in two separate locations at the same time. This would produce a flame wall that grows faster and more uniformly than one lit by a single laser.

The laser is not strong enough to light the leanest fuel mixtures with a single pulse. By using several 800-picosecond-long pulses, however, they can inject enough energy to ignite the mixture completely.

A commercial automotive engine will require 60 Hz (or pulse trains per second), Taira says. He has already tested the new dual-beam laser at 100 Hz. The team is also at work on a three-beam laser that will enable even faster and more uniform combustion.

The laser-ignition system, although highly promising, is not yet being installed into actual automobiles made in a factory. Taira's team is, however, working with a large spark-plug company and with DENSO Corporation, a member of the Toyota Group.

Source: physorg

More information: CLEO: 2011 presentation CMP1, "Composite All-Ceramics, Passively Q-switched Nd:YAG/Cr4+:YAG Monolithic Micro-Laser with Two-Beam Output for Multi-Point Ignition," by Nicolaie Pavel of Romania's National Institute for Laser, Plasma and Radiation Physics; Takunore Taira and Masaki Tsunekane of Japan's Institute for Molecular Science; and Kenji Kanehara of Nippon Soken, Inc., Japan, is at 1:30 p.m. Monday, May 2 in the Baltimore Convention Center.

Provided by Optical Society of America

 

The new form of carbon, which they call T-carbon, has very intriguing physical properties that suggest that it could have a wide variety of applications.

The scientists, Xian-Lei Sheng, Qing-Bo Yan, Fei Ye, Qing-Rong Zheng, and Gang Su, from the Graduate University of Chinese Academy of Sciences in Beijing, China, have published their study on the first-principles calculations of T-carbon in a recent issue of Physical Review Letters.
Allotropes are formed when the atoms in a substance that contains only one type of atom are arranged differently.

Although many substances have multiple allotropes, carbon has the greatest number of known allotropes. The three best-known carbon allotropes are amorphous carbon (such as coal and soot), graphite, and diamond. Since the 1980s, scientists have been synthesizing newer allotropes, including carbon nanotubes, graphene, and fullerenes, all of which have had a significant scientific and technological impact.

With more recent advances in synthetic tools, scientists have been investigating a wide variety of new – and sometimes elusive – carbon allotropes. In light of these investigations, Sheng, et al., write in their study that it appears that we might be entering the era of carbon allotropes.

Here, the scientists explained how to obtain a new carbon allotrope by substituting each carbon atom in diamond with a carbon tetrahedron (hence the name “T-carbon”). They were inspired by the substitution of each carbon atom in methane with a carbon tetrahedron, which forms tetrahedrane.

“[Our study] adds a possible new allotrope of carbon with amazing properties,” Su told PhysOrg.com. “T-carbon has bond angles different from graphite and diamond, but the interesting structure is still quite stable and has the same group symmetry as diamond, thereby widening people’s vision and knowledge on carbon bonding.”

Each unit cell of the T-carbon structure contains two tetrahedrons with eight carbon atoms. As the scientists’ calculations showed, T-carbon is thermodynamically stable at ambient pressure and is a semiconductor. T-carbon is one-third softer than diamond, which is the hardest known natural material. The new carbon allotrope also has a much lower density than diamond, making it “fluffy.”

The scientists also calculated that T-carbon has large interspaces betweenatoms compared to other forms of carbon, which could make it potentially useful for hydrogen storage. In addition, the unique physical properties of this new carbon allotrope make it a promising material for photocatalysis, adsorption, and aerospace applications.
“We believe that, if obtained, T-carbon is so fluffy that it can be used to store hydrogen, lithium, and other small molecules for energy purposes,” Su said. “It can be used as photocatalysis for water-splitting to generate hydrogen, or as an adsorption material for environmental protection. As it has very low density but a high modulus and hardness, it is quite suitable for aerospace materials, sports materials like a tennis racket, golf club, etc., and cruiser skin, and so forth.”

The scientists also noted that T-carbon could have astronomical implications as a potential component of interstellar dust and carbon exoplanets.

New carbon allotrope could have a variety of applications

The structure of the new carbon allotrope, T-carbon, is shown from different directions. T-carbon is obtained by replacing each carbon atom in diamond with a carbon tetrahedron. Image credit: Sheng, et al. ©2011 American Physical Society.

“There is a long-standing puzzle in astronomy known as the ‘carbon crisis’ in interstellar dust,” Su said. “Observations by the Hubble telescope revealed that the carbon budget in dust is deep in the red, and there is not sufficient carbon in dust to account for the light distortions.”

In addition, the exoplanet WASP-12b has recently been found to have a large amount of carbon, making it the first carbon-rich exoplanet ever discovered. Since the structure of the carbon in WASP-12b is still unclear, T-carbon might also be one of possible candidates for this carbon planet.
To investigate T-carbon further, the researchers would like to synthesize the new allotrope in the lab, although they say that this would likely be very difficult.

“A synthesis of T-carbon in the lab poses a great challenge for materials scientists and chemists,” Su said. “We suggest the following ways: using the CVD technique under a negative pressure environment; detonation on diamond or graphite; crystallization of amorphous tetragonal carbon; or stretching cubic diamond under extremely large strength.”

Source: PhysOrg

 

A project allowing avatars to visibly age over time is in the works.

The shop is one of several projects Chang uses to explore humanity in technology. Chang, an electronic artist and recently appointed co-director of the Games and Simulation Arts and Sciences program at Rensselaer, sees the dialogue between perfection and mortality as an important influence in the growing world of games and simulation.

"There's this transcendence that technology promises us. At its extreme is the notion of immortality that -- with artificial intelligence, robotics, and virtual reality -- you could download your consciousness and take yourself out of the limitations of the physical body," said Chang. "But at the same time, that's what makes us human: our frailty and our mortality."

 

In other words, while the "sell" behind technology is often about achieving perfection (with a smart phone all the answers are at hand, with GPS we never lose our way, in Second Life we are beautiful), the risk is a loss of humanity.

That dialogue and tension leads Chang to believe that the nascent world of gaming and simulation could become "a new cultural form" as great as literature, art, music, and theater.

"This is just the beginning; we don't really know what this is going to be, and 'games and simulation' is just the best term we have to describe a much larger form," said Chang. "Twenty years ago nobody knew what the Web was going to be. There was this huge form on the horizon that we were sort of fumbling toward with different technological experiments, artistic experiments; I think this is what's going on with games and simulation right now.

"There are many things that are very difficult to do hands-on -- it's very difficult to simulate a disaster, it's very difficult to manipulate atoms and molecules at the atomic level -- and this is where simulation comes in handy," said Chang. "That kind of learning experience, that way of gaining knowledge that's intuitive, that comes through experience and involvement, can be expanded to many other realms."

As an electronic artist, Chang's own work is at the intersection of virtual environments, experimental gaming, and contemporary media art.

"I'm interested in what you could call evocative and poetic experiences within technological systems -- creating that powerful experience that you can get from great music, theater, books, and paintings through immersive and interactive simulations as well," Chang said. "But I'm also interested in the experiences of being human within technological systems."

Other recent projects include "Becoming," a computer-driven video installation in which the attributes of two animated figures -- each inhabiting their own space -- are interchanged. "Over time, this causes each figure to take on the attributes of the other, distorted by the structure of their digital information."

In "Insecurity Camera," an installation shown at art exhibits around the country, a "shy" security camera turns away at the approach of subjects.

"What I'm interested in is getting at those human qualities that are still there," Chang said. "Some of this has to do with frailty, with fumbling, weakness, and failure. These are things that can get disguised, they can get swept under the rug when we think about technology."

Chang earned a bachelor of arts in computer science from Amherst College, and a master of fine arts in art and technology studies from the Art Institute of Chicago. His installations, performances, and immersive virtual reality environments have been exhibited in numerous venues and festivals worldwide, including Boston CyberArts, SIGGRAPH, the FILE International Electronic Language Festival in Sao Paulo, the Athens MediaTerra Festival, the Wired NextFest, and the Vancouver New Forms Festival, among others. He has designed interactive exhibits for museums such as the Museum of Contemporary Art in Chicago and the Field Museum of Natural History.

Chang teaches a two-semester game development course that joins students with backgrounds in all aspects of games -- computer programming, computer science, design, art, and writing -- in the process of creating games. The students start with a design, and proceed through all the steps of planning, creating art work, writing code, and refining their game.

"Think of it as a foundation into developing games that you can take into experimental game design and stretch beyond it," Chang said.

As the "new cultural form" evolves, Chang sees ample room for exploration.

For example, said Chang, virtual reality, in which experiences are staged in a wholly digital world, leads to different implications than augmented reality, in which digital elements overlay the physical world. One implication of virtual reality -- in which, as in Second Life, users can experiment with their identity -- lies in research which suggests that personal growth gains made within the virtual world transfer to the real world. One implication of augmented reality -- in which users may add digital elements that only they can access -- is the possibility of several people sharing the same physical world while experiencing divergent realities.

In the near term, the most immediate implications for the emerging form are, as might be expected, in entertainment and education.

"What's already happening is this enrichment of the notion of what entertainment is through games," Chang said. "When you talk about games, you often have ideas of simple first-person shooter or action games. But within the realm of entertainment is an immense diversity of possibilities -- from complex emotional dramatic story-based games to casual games on your cell phone. There's this range of ways of playing from competitive, multiplayer, social to creative. This is just within the entertainment realm."

Source: Science Daily

 

They have built a carbon nanotube synapse circuit whose behavior in tests reproduces the function of a neuron, the building block of the brain.The team, which was led by Professor Alice Parker and Professor Chongwu Zhou in the USC Viterbi School of Engineering Ming Hsieh Department of Electrical Engineering, used an interdisciplinary approach combining circuit design with nanotechnology to address the complex problem of capturing brain function.

In a paper published in the proceedings of the IEEE/NIH 2011 Life Science Systems and Applications Workshop in April 2011, the Viterbi team detailed how they were able to use carbon nanotubes to create a synapse.

This image shows nanotubes used in synthetic synapse and apparatus used to create them. (Credit: USC Viterbi School of Engineering).

Carbon nanotubes are molecular carbon structures that are extremely small, with a diameter a million times smaller than a pencil point. These nanotubes can be used in electronic circuits, acting as metallic conductors or semiconductors.

"This is a necessary first step in the process," said Parker, who began the looking at the possibility of developing a synthetic brain in 2006. "We wanted to answer the question: Can you build a circuit that would act like a neuron? The next step is even more complex. How can we build structures out of these circuits that mimic the function of the brain, which has 100 billion neurons and 10,000 synapses per neuron?"

Parker emphasized that the actual development of a synthetic brain, or even a functional brain area is decades away, and she said the next hurdle for the research centers on reproducing brain plasticity in the circuits.

The human brain continually produces new neurons, makes new connections and adapts throughout life, and creating this process through analog circuits will be a monumental task, according to Parker.

She believes the ongoing research of understanding the process of human intelligence could have long-term implications for everything from developing prosthetic nanotechnology that would heal traumatic brain injuries to developing intelligent, safe cars that would protect drivers in bold new ways.

For Jonathan Joshi, a USC Viterbi Ph.D. student who is a co-author of the paper, the interdisciplinary approach to the problem was key to the initial progress. Joshi said that working with Zhou and his group of nanotechnology researchers provided the ideal dynamic of circuit technology and nanotechnology.

"The interdisciplinary approach is the only approach that will lead to a solution. We need more than one type of engineer working on this solution," said Joshi. "We should constantly be in search of new technologies to solve this problem."

Source: ScienceDaily.com

 

But there are some compounds that, although they follow the bonding and valence rules, still are thought to not exist because they have unstable structures. Scientists call these compounds "impossible compounds." Nevertheless, some of these impossible compounds have actually been fabricated (for example, single sheets of graphene were once considered impossible compounds). In a new study, scientists have synthesized another one of these impossible compounds -- periodic mesoporous hydridosilica -- which can transform into a photoluminescent material at high temperatures.

Chemists fabricate 'impossible' material

The researchers, led by Professor Geoffrey Ozin of the Chemistry Department at the University of Toronto, along with coauthors from institutions in Canada, China, Turkey, and Germany, have published their study in a recent issue of theJournal of the American Chemical Society.

Like graphene, periodic mesoporous hydridosilica (meso-HSiO1.5) consists of a honeycomb-like lattice structure. Theoretically, the structure should be so thermodynamically unstable that the mesopores (the holes in the honeycomb) should immediately collapse into a denser form, HSiO1.5, upon the removal of the template on which the material was synthesized.

In their study, the researchers synthesized the mesoporous material on an aqueous acid-catalyzed template. When they removed the template, they discovered that the impossible material remains stable up to 300 °C. The researchers attribute the stability to hydrogen bonding effects and steric effects, the latter of which are related to the distance between atoms. Together, these effects contribute to the material’s mechanical stability by making the mesopores resistant to collapse upon removal of the template.

“The prevailing view for more than 50 years in the massive field of micro-, meso-, or macroporous materials is that a four-coordinate, three-connected open framework material (called disrupted frameworks) should be thermodynamically unstable with respect to collapse of the porosity and therefore should not exist,” Ozin told PhysOrg.com. “The discovery that this class of material can indeed exist with impressive stability is not a special effect related to the choice of the template, but rather that intrinsic hydrogen bonding between the silicon hydride O3SiH units and silanol O3SiOH that pervade the pore walls is strong enough to provide the meso-HSiO1.5 open-framework material with sufficient mechanical strength for it to be able to sustain the porosity intact in the as-synthesized template-containing and template-free material. This discovery is the big scientific surprise – so never say never when it comes to chemical synthesis.”

When raising the temperature above 300 °C, the researchers discovered that the mesoporous material undergoes a “metamorphic” transformation. This transformation eventually yields a silicon-silica nanocomposite material embedded with brightly photoluminescent silicon nanocrystals. Because the novel nanocomposite material retains its periodic mesoporous structure, the nanocrystals are evenly distributed throughout the structure. According to the researchers, the origin of the photoluminescence likely arises from quantum confinement effects inside the silicon nanocrystals.

In addition, the researchers found that they could control the photoluminescent properties of the nanocrystals by changing the thermal treatment. They predict that this ability could allow the bright nanocrystals to be used in the development of light-emitting devices, solar energy devices, and biological sensors.

“Now we have a periodic mesoporous hydridosilica in which we can exploit the chemistry of the silicon-hydride bonds that permeate the entire void space of the material,” Ozin said. “Every silicon in the structure has a Si-H bond to play creative synthetic games. This is a big deal in terms of it serving as a novel solid-state reactive host material within which one can perform novel chemistry limited only by one’s imagination, and a myriad new materials will emerge with a cornucopia of opportunities for creative discovery and invention.”

Source: PhysOrg

 
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Titolo
en - Global Observatory (605)
en - Science and Society (594)
en - Video Alert (346)
it - Osservatorio Globale (503)
it - Scienze e Societa (555)
it - Video Alerta (132)
ro - Observator Global (399)
ro - Stiinta si Societate (467)
ro - TV Network (149)
z - Games Giochi Jocuri (68)

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Ultimi commenti - Last comments - Ultimele comentarii:
Hi, it's Nathan!Pretty much everyone is using voice search with their Siri/Google/Alexa to ask for services and products now, and next year, it'll be EVERYONE of your customers. Imagine what you are ...
15/01/2019 @ 17:58:25
By Nathan
Now Colorado is one love, I'm already packing suitcases;)
14/01/2018 @ 16:07:36
By Napasechnik
Nice read, I just passed this onto a friend who was doing some research on that. And he just bought me lunch since I found it for him smile So let me rephrase that Thank you for lunch! Whenever you ha...
21/11/2016 @ 09:41:39
By Anonimo


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