#New transistors offer high output at low voltage A new type of transistor could pave the way for fast computing devices that would use very low energy including smart sensor networks and implanted medical devices.
Called a near broken-gap tunnel field effect transistor (TFET) the new device uses the quantum mechanical tunneling of electrons through an ultrathin energy barrier to provide high current at low voltage.
Tunnel field effect transistors are considered to be a potential replacement for current CMOS transistors as device makers search for a way to continue shrinking the size of transistors and packing more transistors into a given area.
The main challenge facing current chip technology is that as size decreases the power required to operate transistors does not decrease in step.
The results can be seen in batteries that drain faster and increasing heat dissipation that can damage delicate electronic circuits.
Various new types of transistor architecture using materials other than the standard silicon are being studied to overcome the power consumption challenge. his transistor has previously been developed in our lab to replace MOSFET transistors for logic applications
and Penn State graduate student Bijesh Rajamohanan. n this work we went a step beyond and showed the capability of operating at high frequency
which is handy for applications where power concerns are critical such as processing and transmitting information from devices implanted inside the human body
while draining the battery requires frequent replacement surgery. The researchers led by Suman Datta professor of electrical engineering tuned the material composition of the indium gallium arsenide/gallium arsenide antimony
so that the energy barrier was close to zeroâ##or near broken gap which allowed electrons to tunnel through the barrier when desired.
To improve amplification the researchers moved all the contacts to the same plane at the top surface of the vertical transistor.
A team of researchers from Penn State the National Institute of Standards and Technology and IQE a specialty wafer manufacturer jointly presented their findings at the International Electron Devices Meeting in WASHINGTON DC.
This device was developed as part of a larger program sponsored by the National Science Foundation e
#Rapid TB test could be ready in 18 months A new rapid tuberculosis test shortens diagnosis time on one of the world s deadliest diseases from several weeks to a few hours.
The disease caused by various strains of mycobacteria attacks the lungs or other organs and is spread through the air when an individual with active form of TB coughs or sneezes.
One in ten cases progress to the active disease which presents symptoms such as a chronic cough coughing up bloody sputum (mucus) fever night sweats and weight loss.
If left untreatedâ##a common scenario in developing countries lacking the infrastructure or resources to efficiently screen and follow up with infected patientsâ##a person with active TB has only a 50 percent chance of survival.
Jeffrey Cirillo professor in the Department of Microbial Pathogenesis and Immunology at Texas A&m Health Science Center (TAMHSC) College of Medicine and his team have discovered a new method to spot the bacteria that causes
TB a profound advance in point-of-care diagnosis of the disease. e ve identified a fluorescence substrate that reacts with the bacteriacirillo says. his gives us a very sensitive signal that wouldn t be possible otherwise. nce sputum samples
are combined with the reactive substance a battery-powered handheld reader is used then to detect any fluorescence
and deliver the diagnosis. here isn t a diagnostic tool comparable to this in terms of allowing patients to rapidly determine
whether or not they are infected. hile other TB tests exist they take several days to produce results.
It has not been previously possible to target a specific TB enzyme as a diagnostic for this disease.
Chemistry has letters of support from the World health organization Doctors Without Borders and the Clinton Health Access Initiative.
Cirillo is now seeking late-stage funding for the additional testing required to replicate his findings in independent labs a crucial final step before production
and validation in multiple labs outside our Own right now we re at maybe an 18-month window for this device to be out serving patients. he Bill
and Melinda Gates Foundation and the Wellcome Trust funded the project d
#Craters within crater hint at moonâ#diversity Brown University right Original Studyposted by Kevin Stacey-Brown on December 9 2013 Small craters on the moon that are within one of the largest
craters in the solar system may offer clues as to how the moon formed. A massive impact on the moon about 4 billion years ago left the 2500-mile crater.
Data from the Moon Mineralogy Mapper that flew aboard India'#Chandrayaan-1 lunar orbiter shows a diverse mineralogy in the subsurface of the giant South pole Aitken basin.
The differing mineral signatures could be reflective of the minerals dredged up at the time of the giant impact.
Using Moon Mineralogy Mapper data the researchers looked at the light reflected from each of the four central peaks.
One of the four craters located toward the outer edge of the basin contained several distinct mineral deposits within its own peak possibly due to sampling a mixture of both upper
The varying mineralogy in these central peaks suggests that the SPA subsurface is much more diverse than previously thought. revious studies have suggested that all the central peaks look very similar
and that was taken as evidence that everything'#the same across the basinsays Dan Moriarty a graduate student at Brown University. e looked in a little more detail
and found significant compositional differences between these central peaks The Moon Mineralogy Mapper has very high spatial and spectral resolution.
It'#possible that the distinct minerals formed as the molten rock from the SPA impact cooled.
and mantle. f you do the impact scaling from models (the SPA impact) should have excavated into the mantlemoriarty says. e think the upper mantle is rich in a mineral called olivine
but we don't see much olivine in the basin. hat'#one of the big mysteries about the South pole Aitken basin.
and it doesn'##t contain olivine that would have substantial implications for models of how the Moon was formed Moriarty says.
Carle Pieters professor of geological sciences at Brown and Peter Isaacson from the University of Hawaii were also authors of the paper.
#Laser light creates hologram the width of a hair Purdue University rightoriginal Studyposted by Emil Venere-Purdue on December 9 2013researchers have created tiny holograms using a etasurfacecapable of the ultra-efficient control of light.
The finding offers a potential new technology for advanced sensors high-resolution displays and information processing.
The metasurface thousands of V-shaped nanoantennas formed into an ultrathin gold foil could make possible lanar photonicsdevices
and optical switches small enough to be integrated into computer chips for information processing sensing and telecommunications says Alexander Kildishev associate research professor of electrical and computer engineering at Purdue University.
Laser light shines through the nanoantennas creating the hologram 10 microns above the metasurface. f we can shape characters we can shape different types of light beams for sensing
or recording or for example pixels for 3d displays. Another potential application is the transmission and processing of data inside chips for information technologykildishev says. he smallest featuresâ##the strokes of the lettersâ##displayed in our experiment are only 1 micron wide.
This is a quite remarkable spatial resolution. etasurfaces could make it possible to use single photonsâ##the particles that make up lightâ##for switching
and routing in future computers. While using photons would dramatically speed up computers and telecommunications conventional photonic devices cannot be miniaturized
because the wavelength of light is too large to fit in tiny components needed for integrated circuits. Nanostructured metamaterials however are making it possible to reduce the wavelength of light allowing the creation of new types of nanophotonic devices says Vladimir M. Shalaev scientific director of nanophotonics at Purdue s Birck Nanotechnology Center
and professor of electrical and computer engineering. he most important thing is that we can do this with a very thin layer only 30 nanometers
and this is unprecedentedshalaev says. his means you can start to embed it in electronics to marry it with electronics. he layer is about 1/23rd the width of the wavelength of light used to create the holograms.
Formerly of Purdue Xingjie Ni a postdoctoral researcher at University of California Berkeley is co-author of the paper with Kildishev and Shalaev.
The findings appear in Nature Communications. Under development for about 15 years metamaterials owe their unusual potential to precision design on the scale of nanometers.
Optical nanophotonic circuits might harness clouds of electrons called urface plasmonsto manipulate and control the routing of light in devices too tiny for conventional lasers.
The researchers have shown how to control the intensity and phase or timing of laser light as it passes through the nanoantennas.
Each antenna has its own hase delayow much light is slowed as it passes through the structure.
Controlling the intensity and phase is essential for creating working devices and can be achieved by altering the V-shaped antennas.
The US Air force Office of Scientific research Army Research Office and the National Science Foundation partially funded the research.
Purdue has filed a provisional patent application on the concept. Source: Purdue Universityyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license e
#From coal, cheap quantum dots in one step Chemists have discovered how to reduce three kinds of coal into graphene quantum dots (GQDS) that could be used for medical imaging as well as sensing electronic and photovoltaic applications.
Band gaps determine how a semiconducting material carries an electric current. In quantum dots microscopic discs of atom-thick graphene oxide band gaps are responsible for their fluorescence
and can be tuned by changing the dots'##size. The new process described in the journal Nature Communications allows a measure of control over their size generally from 2 to 20 nanometers depending on the source of the coal.
There are many ways to make GQDS now but most are expensive and produce very small quantities says James Tour chair in chemistry and professor of mechanical engineering and materials science and of computer science at Rice university.
Earlier research found a way last year to make GQDS from relatively cheap carbon fiber
but coal promises greater quantities of GQDS made even cheaper in one chemical step. e wanted to see what'#there in coal that might be interesting so we put it through a very simple oxidation proceduretour says.
That involved crushing the coal and bathing it in acid solutions to break the bonds that hold the tiny graphene domains together. ou can'##t just take a piece of graphene
and easily chop it up this small. our worked with co-author Angel Mart assistant professor of chemistry
and bioengineering to characterize the product It turns out different types of coal produce different types of dots.
GQDS were derived from bituminous coal anthracite and coke a byproduct of oil refining. The coals were each sonicated in nitric and sulfuric acids and heated for 24 hours.
Bituminous coal produced GQDS between 2 and 4 nanometers wide. Coke produced GQDS between 4 and 8 nanometers and anthracite made stacked structures from 18 to 40 nanometers with small round layers atop larger thinner layers.
Just to see what would happen the researchers treated graphite flakes with the same process
and got mostly smaller graphite flakes.)The dots are water-soluble and early tests have shown them to be nontoxic offering the promise that GQDS may serve as effective antioxidants Tour says.
Medical imaging could also benefit greatly as the dots show robust performance as fluorescent agents. ne of the problems with standard probes in fluorescent spectroscopy is that
when you load them into a cell and hit them with high-powered lasers you see them for a fraction of a second to upwards of a few seconds
and that'#itmart says. hey'##re still there but they have been bleached photo. They don't fluoresce anymore. esting in the Mart lab showed GQDS resist bleaching.
After hours of excitation the photoluminescent response of the coal-sourced GQDS was affected barely That could make them suitable for use in living organisms. ecause they'##re so stable they could theoretically make imaging more efficienthe says.
A small change in the size of a quantum dot as little as a fraction of a nanometer##changes its fluorescent wavelengths by a measurable factor
and that proved true for the coal-sourced GQDS Mart says. Low cost will also be a draw Tour says. raphite is $2000 a ton for the best there is from the UK.
Cheaper graphite is $800 a ton from China. And coal is $10 to $60 a ton. oal is the cheapest material you can get for producing GQDS
and we found we can get a 20 percent yield. So this discovery can really change the quantum dot industry.
It'#going to show the world that inside of coal are these very interesting structures that have real value. he Air force Office of Scientific research
and the Office of Naval Research funded the work through their Multidisciplinary University Research Initiatives. Source:
Rice university s
#irtual wall blocks oil spills from spreading Researchers have designed an invisible allthat stops oily liquids from spreading
and confines them to a certain area. The outer shell of a droplet of oil on a surface has a thin skin
which allows it to hold its shape like a small dome known as the liquid's surface tension.
and effective blockage of oil spreading. ur work is based on micro/nanoelectromechanical systems or M/NEMS
or mechanical structures that allow researchers to conduct their work on the micro/nanoscopic levelsays Jae Kwon associate professor of electrical and computer engineering at the University of Missouri. il-based materials or low-surface tension liquids
and spread very easily pose challenges to researchers who need to control those tiny oil droplets on microdevices. il-based compounds are referred to as low-surface tension liquids
researcher's microscope slides or microarrays where the liquids are placed. Also as can be seen from oil spills in the Gulf of mexico oil can stick
and his group demonstrated invisible irtual wallsthat block spreading of low-surface tension liquids at the boundary line with microscopic features already created in the device. ur newly developed surface helped keep oil
and virtual walls for low-surface tension liquids also have immense potential for many lab-on-a-chip devices
which are crucial to current and future research techniques. n the future oil-repellent virtual walls may be used to control the transport of oil without spillage Kwon says w
#Search tool finds pics of you based on tag relationships University of Toronto Posted by Michael Kennedy-Toronto on December 2 2013a new algorithm could profoundly change the way we find photos among the billions on social media sites such as Facebook
Because of your close aggingrelationship with both your mother in the first picture and your father in the second the algorithm can determine that a relationship exists between those two
when you search for photos of your father the algorithm can return the untagged photo because of the very high likelihood he s pictured. wo things are happening:
and we can search images bettersays Parham Aarabi a professor in the Department of Electrical
and Computer engineering at the University of Toronto who helped develop the algorithm. The tool called relational social image search achieves high reliability without using computationally intensive objector facial recognition software. f you want to search a trillion photos normally that takes at least a trillion operations.
It s based on the number of photos you havesays Aarabi. acebook has almost half a trillion photos
but a billion usersâ##it s almost a 500 order of magnitude difference. ur algorithm is simply based on the number of tags not on the number of photos
which makes it more efficient to search than standard approaches. urrently the algorithm s interface is primarily for research
but Aarabi aims to see it incorporated on the back-end of large image databases or social networks. envision the interface would be exactly like you use Facebook searchâ##for users nothing would change.
They would just get better resultssays Aarabi. The National Science and Engineering Research Council of Canada supported the project.
It will be presented at the IEEE International Symposium on Multimedia Dec 10 2013. This month the United states Patent and Trademark Office will issue a patent on this technology.
University of Torontoyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license N
#DNA helps nanoparticle crystals self-assemble Northwestern University rightoriginal Studyposted by Megan Fellman-Northwestern on December 2 2013using the same structure found in nature researchers have built the first near-perfect single crystals
out of gold nanoparticles and DNA. ingle crystals are the backbone of many things we rely onâ##diamonds for beauty as well as industrial applications sapphires for lasers
and silicon for electronicssays nanoscientist Chad A. Mirkin. he precise placement of atoms within a well-defined lattice defines these high-quality crystals. ow we can do the same with nanomaterials
and DNA the blueprint of lifemirkin adds. ur method could lead to novel technologies and even enable new industries
much as the ability to grow silicon in perfect crystalline arrangements made possible the multibillion-dollar semiconductor industry. irkin s
research group developed the ecipefor using nanomaterials as atoms DNA as bonds and a little heat to form tiny crystals.
This single-crystal recipe builds on superlattice techniques Mirkin s lab has been developing for nearly two decades.
In this recent work Mirkin an experimentalist and professor of Chemistry in the Weinberg College of Arts and Sciences teamed up with Monica Olvera de la Cruz a theoretician
and professor of materials science and engineering in the Mccormick School of engineering and Applied science to evaluate the new technique
Given a set of nanoparticles and a specific type of DNA Olvera de la Cruz showed they can accurately predict the 3d structure
and shape of crystals they can build. The team worked with gold nanoparticles but the recipe can be applied to a variety of materials with potential applications in the fields of materials science photonics electronics
and catalysis. A single crystal has order: its crystal lattice is continuous and unbroken throughout. The absence of defects in the material can give these crystals unique mechanical optical and electrical properties making them very desirable.
In the study strands of COMPLEMENTARY DNA act as bonds between disordered gold nanoparticles transforming them into an orderly crystal.
The researchers determined that the ratio of the DNA linker s length to the size of the nanoparticle is critical. f you get the right ratio it makes a perfect crystalâ##isn t that fun?
says Olvera de la Cruz who also is a professor of chemistry in the Weinberg College of Arts
and Sciences. hat s the fascinating thing that you have to have the right ratio.
We are learning so many rules for calculating things that other people cannot compute in atoms in atomic crystals. he ratio affects the energy of the faces of the crystals
which determines the final crystal shape. Ratios that don t follow the recipe lead to large fluctuations in energy
and result in a sphere not a faceted crystal she explained. With the correct ratio the energies fluctuate less
and result in a crystal every time. magine having a million balls of two colors some red some blue in a container
and you try shaking them until you get alternating red and blue ballsmirkin explained. t will never happen. ut
if you attach DNA that is complementary to nanoparticlesâ##the red has one kind of DNA say the blue its complementâ
##and now you shake or in our case just stir in water all the particles will find one another
and link togetherhe says. hey beautifully assemble into a three-dimensional crystal that we predicted computationally
and realized experimentally. o achieve a self-assembling single crystal in the lab the research team reports taking two sets of gold nanoparticles outfitted with COMPLEMENTARY DNA
Working with approximately 1 million nanoparticles in water they heated the solution to a temperature just above the DNA linkers melting point
The very slow cooling process encouraged the single stranded-dna DNA to find its complement resulting in a high-quality single crystal approximately three microns wide. he process gives the system enough time
and energy for all the particles to arrange themselves and find the spots they should be inmirkin says.
The researchers determined that the length of DNA connected to each gold nanoparticle can t be much longer than the size of the nanoparticle.
In the study the gold nanoparticles varied from five to 20 nanometers in diameter; for each the DNA length that led to crystal formation was about 18 base pairs and six single-base ticky ends.?
There s no reason we can t grow extraordinarily large single crystals in the future using modifications of our techniquesays Mirkin who also is a professor of medicine chemical and biological engineering biomedical engineering and materials science and engineering and director of the university s International Institute for Nanotechnology.
The Air force Office of Scientific research supported the research. Source: Northwestern Universityyou are free to share this article under the Creative Commons Attribution-Noderivs 3. 0 Unported license t
#Quantum wells flash light without magnets Spontaneous bursts of light from a solid block illuminate the unusual way interacting quantum particles behave
The discovery of a way to trigger these flashes may lead to new telecommunications equipment
The Rice university lab of Junichiro Kono found the flashes which last trillionths of a second change color as they pulse from within a solid-state block.
and Fermi-edge singularities a process known to occur in metals. The team previously reported the first observation of superfluorescence in a solid-state system by strongly exciting semiconductor quantum wells in high magnetic fields.
The new processâ##Fermi-edge superfluorescenceâ##does not require them to use powerful magnets. That opens up the possibility of making compact semiconductor devices to produce picosecond pulses of light.
Previous experiments showed the ability to create superfluorescent bursts from a stack of quantum wells excited by a laser in extreme cold and under the influence of a strong magnetic field both
but mysteries remained especially in results obtained at low or zero magnetic fields. Kono says the team didn t understand at the time why the wavelength of the burst changed over its 100-picosecond span.
but also managed to record it without having to travel to the National High Magnetic field Laboratory at Florida State.
when triggered by an external source of energy. However electrons and holes in semiconductors are charged particles
so they interact more strongly than atoms or molecules do. The quantum well as before consisted of stacked blocks of an indium gallium arsenide compound separated by barriers of gallium arsenide. t s a unique solid-state environment where many-body effects completely dominate the dynamics of the systemkono says. hen a strong magnetic field is applied electrons
and holes are fully quantizedâ##that is constrained in their range of motionâ##just like electrons in atomshe says. o the essential physics in the presence of a high magnetic field is quite similar to that in atomic gases.
But as we decrease and eventually eliminate the magnetic field we re entering a regime atomic physics cannot access where continua of electronic states
or bands exist. he Kono team s goal was to keep the particles as dense as possible at liquid helium temperatures (about-450 degrees Fahrenheit)
when the so-called Fermi energy is much larger than the thermal energy. When pumped by a strong laser these quantum degenerate particles gathered energy
and released it as light at the Fermi edge: the energy level of the most energetic particles in the system.
As the electrons and holes combined to release photons the edge shifted to lower energy particles
but it required high magnetic fields so there was no practical application. But now the present work demonstrates that we don t need a magnet. he team included co-lead authors Timothy Noe a Rice postdoctoral researcher and Ji-Hee Kim a former Rice postdoctoral researcher and now a research
professor at Sungkyunkwan University in the Republic of korea. Co-authors contributed from Florida State university and Texas A&m University.
The National Science Foundation and the state of Florida supported the research. Source: Rice Universit p
#Computer gets smarter by looking at online pics 24-7 Carnegie mellon University Posted by Byron Spice-Carnegie mellon on November 26 2013a computer program called the Never Ending Image Learner (NEIL) is running 24
hours a day searching the internet for images and doing its best to understand them on its own.
As NEIL s visual database grows the computer program gains common sense on a massive scale. NEIL leverages recent advances in computer vision that enable computer programs to identify
and label objects in images to characterize scenes and to recognize attributes such as colors lighting and materials all with a minimum of human supervision.
In turn the data it generates will further enhance the ability of computers to understand the visual world
But NEIL also makes associations between these things to obtain common sense information that people just seem to know without ever saying##that cars often are found on roads that buildings tend to be vertical
and that ducks look sort of like geese. Based on text references it might seem that the color associated with sheep is black
but people##and NEIL##nevertheless know that sheep typically are white. mages are the best way to learn visual propertiessays Abhinav Gupta assistant research professor in Carnegie mellon University s Robotics Institute. mages
also include a lot of common sense information about the world. People learn this by themselves and with NEIL we hope that computers will do
so as well. computer cluster has been running the NEIL program since late July and already has analyzed three million images identifying 1500 types of objects in half a million images and 1200 types of scenes in hundreds of thousands of images.
It has connected the dots to learn 2500 associations from thousands of instances. One motivation for the NEIL project is to create the world s largest visual structured knowledge base where objects scenes actions attributes
and catalogued. hat we have learned in the last 5 to 10 years of computer vision research is that the more data you have the better computer vision becomesgupta says.
Some projects such as Imagenet and Visipedia have tried to compile this structured data with human assistance.
But the scale of the Internet is so vast##Facebook alone holds more than 200 billion images that the only hope to analyze it all is to teach computers to do it largely by themselves.
Abhinav Shrivastava a Phd student in robotics says NEIL can sometimes make erroneous assumptions that compound mistakes
A Google Image search for instance might convince NEIL that inkis just the name of a singer rather than a color. eople don t always know how or
what to teach computershe says. ut humans are good at telling computers when they are wrong. eople also tell NEIL what categories of objects scenes etc. to search
It can be anticipated for instance that a search for pplemight return images of fruit as well as laptop computers.
But Gupta and his landlubbing team had no idea that a search for F-18 would identify not only images of a fighter jet but also of F18-class catamarans.
or cars come in a variety of brands and models. And it begins to notice associations##that zebras tend to be found in savannahs for instance
The program runs on two clusters of computers that include 200 processing cores. The Office of Naval Research and Google Inc. support the project.
The research team will present its findings on Dec 4 at the IEEE International Conference on Computer Vision in Sydney Australiasource:
Carnegie mellon Universit t
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