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Science & Technology News (986)

New Means Discovered to Control Light in Photonic Systems

Category: Science & Technology
Posted: July 31, 2015 01:37PM
Author: Guest_Jim_*

Photons are poised to become a dominant medium for transmitting information, as they travel very quickly and can carry a lot of information. They can also be placed into quantum states to build quantum networks, but working with light can be difficult as it is emitted in all directions and will go in both directions along photonic channels. Researchers at the Niels Bohr Institute, however, have found a solution to these difficulties with quantum dots.

Quantum dots are nano-sized semiconductor crystals that can have their properties precisely tuned. This tuning makes it possible to pump them with enough energy to emit a single photon of a specific frequency, which is very valuable for photonic and quantum systems. What the researchers discovered with a photonic chip, in which a quantum dot was embedded, was that the quantum spin of the dot determined the direction the emitted photon travelled along, through the photonic channel. This level of control is very useful and can also improve efficiency, as now the light is all going in the same direction.

Another consequence of this discovery is that the photonic channel appears to be different lengths, depending on the end a photon enters. From one end, the photon will just travel directly through the channel, but from the other end, going in the opposite direction the photon will interact with the quantum dot. This interaction causes the photon to slow down, making the length of the channel seem longer, due to the delay. This also opens up new applications, and because the materials involved are already used in the semiconductor industry, they have a head start to becoming reality, though a great deal of work still needs to be done.

Source: University of Copenhagen, Niels Bohr Institute

Vulnerability and Possible Fix Found for Tor Network

Category: Science & Technology
Posted: July 31, 2015 06:08AM
Author: Guest_Jim_*

Security and privacy are two points that have become very important to many Internet users in recent years, and are continuing to become more important all the time. One means to achieve these goals is to use the Tor network as a user and as a destination site. Researchers at MIT and the Qatar Computing Research Institute, however, have found ways to successfully attack the network, but also suggest means of addressing these issues.

The Tor network uses what is known as onion routing, where a request made by a user is hidden within layers of encryption. The request is then sent to a random computer in the Tor network, called a guard in this case, which removes one layer of encryption and passes on the request to another, random computer. This continues until the request is completely unencrypted and the final destination is connected to, and at this point no guards involved know both the destination and the sender. It is also possible to use the Tor network to hide sites, by creating introduction points that alone know the address of the destination. Once the user and host computers connect though, another Tor router is added to the circuit, as a private rendezvous point.

What the researchers discovered is that an attacker could, if it is acting as a guard along a chain, infer based on the packets it is routing, determine whether the circuit created is a web-browsing circuit, introduction-point circuit, or a rendezvous circuit. Using similar packet analysis, an attacker could also identify computers that are hosting a hidden site and determine what sites a user is accessing, all without breaking any encryption.

To protect against this the researchers recommend adding dummy packets to the sequences. These packets will serve to obfuscate the type of circuit being made, as each will look similar to the other. However more work still needs to be done to ensure this suggestion will indeed fix the issue.

Source: MIT

President Obama Signs Executive Order to Build World’s Fastest Supercomputer by 2025

Category: Science & Technology
Posted: July 31, 2015 03:47AM
Author: Brentt Moore

President Obama has officially signed an Executive Order that establishes the National Strategic Computing Initiative, which will ensure that the United States builds the world’s fastest supercomputer by 2025. The goal of NSCI is to build a machine that is capable of one exaflop of computing power, allowing for massive developments in government and public sectors such as military, medical, aerospace, and more. While this supercomputer is supposed to be built within the next decade, the initiatives undertaken by NSCI span multiple decades from now, with the new effort ensuring that the United States leads the world in computing power by harnessing the computational capabilities provided by High-Performance Computing systems. The President’s Council of Advisors on Science and Technology noted that High-Performance Computing "must now assume a broader meaning, encompassing not only flops, but also the ability, for example, to efficiently manipulate vast and rapidly increasing quantities of both numerical and non-numerical data."

At this moment in time, the world’s fastest supercomputer for roughly two and a half years has been China's Tianhe-2, and the United States is behind Japan as well in regards to supercomputer speed. With the backing of the federal government, however, and the benefits that the United States is expecting to see by harnessing the computational power of the world’s faster supercomputer, America is likely to become a major leader in supercomputers for quite some time.

Source: The White House

New Optical Modulator Developed for Future Communications

Category: Science & Technology
Posted: July 30, 2015 06:21AM
Author: Guest_Jim_*

In order to send information using photons, it is necessary to modulate the optical signal to encode the data. While optical modulators do exist, they are fairly bulky, inefficient, and expensive. That is set to change though, thanks to researchers at ETH Zurich.

The researchers have created a new modulator design that exploits plasmon-polaritons, which are combinations of electromagnetic fields and electrons, inheriting some of the benefits of both. The primary benefit here is that they allow the optical information to be fit into a much smaller space than photons would allow, as it is now electrons carrying the information. To actually create the modulator though, the researchers take inspiration from optics to create a plasmonic interferometer. It works by splitting the plasmon-polaritons into two half signals, passing these down different arms, and recombining them after the journey. By varying the refractive index of one of the arms though, the phase of one of the halves can be changed, causing interference in the recombined signal, when it is converted back into photons.

This new modulator is made of gold on glass, with an organic material that can have its refractive index change, and it comes in at just 150 nm thick. Being so small it also uses far less power, needing just thousandths of a Watt to achieve a rate of 70 Gbps, which is a hundredth of what current commercial models require.

Source: ETH Zurich

Speed Record of 90 GHz Set for Fluorescence

Category: Science & Technology
Posted: July 29, 2015 06:24AM
Author: Guest_Jim_*

If photonics are ever going to replace electronics in computers, they will have to be able to operate at comparable speeds. Currently lasers dominate when it comes to create superfast pulses, but they are inefficient and too bulky to fit onto silicon chips. This is why researchers at Duke University have developed a new device using plasmonics that can create pulses of light turned on and off 90 billion times a second.

The device the researchers built to achieve this consists of a silver nanocube and a thin gold film, with quantum dots sandwiched between. When a laser shines on the nanocube, plasmons are created, which are the result of electrons and photons coupling together on the metal. The plasmons create an intense electromagnetic field between the nanocube and the gold film, and the quantum dots in the middle interact with it as well. This interaction causes the dots to efficient emit directional light, and it can be turned on and off at the impressive 90 GHz rate.

The next step the researchers intend to take include trying to make this into a single photon source, for use in quantum communications, and to integrate the technology into devices excited optically or electrically.

Source: Duke University

Super-Elastic Conductive Fibers Created

Category: Science & Technology
Posted: July 28, 2015 02:02PM
Author: Guest_Jim_*

Flexible electronics will likely be a big deal once all of the components for them are developed, as there are many situations where flexibility would be invaluable for a device. One catch has been that typically when you stretch a conductive fiber, its conductivity decreases because of how the geometry changes. Researchers at the University of Texas, Dallas have designed a new fiber however, that actually sees its conductivity increase when stretched.

This new fiber consists of a rubber core with an aerogel of carbon nanotubes wrapped around it. The rubber is naturally stretchy, but to make the nanotubes stretchable the researchers had to design how the fibers would buckle. This is similar in concept to the folds in an accordion, which allows those inelastic materials to be stretched. The buckling was controlled by where large and small buckles were present along the nanotube sheath, and it is also these buckles that ensure the fibers' conductivity when stretched. Electrons are able to travel along the length of the hierarchically buckled sheath just as easily as they can travel over a straight sheath. The buckling around the circumference also protects from misalignment, preventing resistance from increasing as the fibers are stretched.

The researchers found that the conductive fibers can be stretched to 14 times their original length, and that conductivity increases 200-fold when stretched. They were also able to make the fibers into capacitors by adding a rubber layer and another nanofiber sheath, and when stretched the capacitance also increased. Both as a conductive elastic fiber and as elastic capacitors, these fibers can find many applications, and the researchers say it is well-suited for rapid commercialization too, so we may see some of those applications before long.

Source: University of Texas, Dallas

Algorithms Combined to Improve Robot Recognition

Category: Science & Technology
Posted: July 28, 2015 06:42AM
Author: Guest_Jim_*

Eventually we may have highly capable robots in our homes, helping with chores and other tasks as we ask them, but before this can happen, they must be able to recognize the objects being used. To that end many objection recognition algorithms have been developed and work is ongoing to make ever better ones. Now researchers at MIT have combined object recognition with mapping algorithms to create a more capable system, without relying on special hardware.

The researchers specialize in SLAM or simultaneous localization and mapping, which is a method for a robot to map their environment using multiple camera views. This generates a 3D map of the area and the objects in it using a single RGB camera. Normally an object recognition system using a single RGB camera works on single frames and relies on colors to distinguish objects from each other, so two objects near each other may be hard to tell apart, especially if they are similarly colored. As SLAM data includes depth information though, combining SLAM with object recognition makes it easier to distinguish objects from each other, and then identify.

The researchers found their new method was able to compete with systems specially designed for objection recognition that use cameras capable of making depth measurements, like the Kinect, despite using a single, monocular camera. It also performs better outside, where the infrared light the Kinect uses is easily lost.



Source: MIT

Wireless Power Transfer Efficiency Doubled

Category: Science & Technology
Posted: July 27, 2015 06:44AM
Author: Guest_Jim_*

Wirelessly charging our devices has been a dream for many for a long time, and now we are starting to see it, but it still needs some work. For the technology to become more practical, its efficiency must be increased, and one means to achieve that is to add intermediate materials between the transmitter and receiver. Metamaterials are one contender for this position, but researchers at North Carolina State University have found an alternative that could be even better.

Wireless power transfer works by generating a magnetic field from one coil and having a receiving coil, in your device, draw energy from that field, some distance away. As magnetic fields go in all directions, the energy they hold can quickly dissipate, so focusing the field can significantly improve efficiency. As metamaterials can interact with various fields in special ways, they make sense to use here, but the researchers found that magnetic resonance field enhancers (MRFEs), as simple as a copper loop, can actually surpass metamaterials. This is thanks to how the MRFEs couple with the magnetic fields, causing less energy to be lost to the material.

When tested against metamaterials, the MRFE was five times more efficient, and fifty times better than when the energy was transferred through the air alone. That is very significant and could do a lot to enable new wireless charging applications beyond phones and tablets, to potentially electric vehicles.

Source: North Carolina State University

Replacing Injections with Dissolvable Microneedles

Category: Science & Technology
Posted: July 24, 2015 02:06PM
Author: Guest_Jim_*

Vaccinations save millions of lives every year, which makes it important to make them easier and safer to use. This is easier said than done though, as traditional needle injections come with some risk and can require a level of medical training. As published in Biomaterials, researchers at Osaka University have developed a new vaccination solution that addresses many of these problems, and may even be superior to needle injections.

The basic idea being employed by the MicroHyala method is to use microneedles to apply the vaccine, instead of a single, larger needle. This use of microneedles is not new, but previous efforts have used silicon or metal needles, which can be problematic if they break off in the skin. Instead of these materials, the Osaka researchers are using hyaluronic acid, which is a natural substance found in our joints. Hyaluronic acid dissolves in water, so when the patch is applied like plaster, the microneedles, which have penetrated the top of the skin, will dissolve into the body, bringing the vaccine along.

The researchers tested their new patch by immunizing people against three kinds of the flu, sing the patch and traditional needle injections. No one had a bad reaction to the patch, and the patch was shown to be as good, or even better than the needle injection method. This work is very important because it could change how vaccines are applied around the world, and make it easier for many vaccinate people in areas with limited medical resources.

Source: Elsevier

Quantum Mechanics Brought Out at Room Temperatures

Category: Science & Technology
Posted: July 24, 2015 06:43AM
Author: Guest_Jim_*

Since its discovery, quantum mechanics has been a realm largely separate from the classical world we live in. This makes it challenging to study some quantum phenomena, which require ultra-low temperature, just above absolute zero. One example of this is Bose-Einstein condensates, but researchers at Polytechnique Montréal and Imperial College London have successfully created a polariton condensate at room temperature.

Polaritons are a quasiparticle formed from the coupling of light and matter and condensates are created when a large number of bosons are all given the same quantum state. To create the polariton condensate, the researchers placed a 100 nm thick film of organic molecules between two mirrors and fired a laser at it. The researchers then observed the blue light that was emitted to study it. Not only was this accomplished at room temperatures, but its scale was also near that of a human hair, which is far larger than most quantum systems.

This work could lead to a number of things, including advanced technologies like polariton lasers and transistors that operate on light. It is also significant because of the use of organic molecules, instead of the ultra-pure, inorganic crystals typically required for this work.

Source: Polytechnique Montréal

Friction Removed on the Macroscale for the First Time

Category: Science & Technology
Posted: July 23, 2015 01:56PM
Author: Guest_Jim_*

For many systems, friction is an enemy as it takes away energy that could otherwise be used, or wears down components. Ways to reduce and remove friction are naturally very important then, with the ultimate goal being superlubricity. When superlubricity is achieved, friction seems to vanish, and now researchers at Argonne National Laboratory have discovered a way to bring it to the macroscale.

Like many discoveries, this one was made almost by accident when the researchers were studying a new lubricant material comprised of graphene and diamond-like carbon (DLC). When the material was modelled on a supercomputer, the results indicated the graphene was rolling up into hollow cylinders, or scrolls. These scrolls are what led to the superlubricity by separating the surfaces involved. Prior to the modelling, testing the lubricant demonstrated the friction would fluctuate, which the model explained. When the scrolls formed, friction would practically vanish, but they would then collapse due to the pressure on them, causing the friction to return. The researchers were able to solve this problem by adding nanodiamond particles, which the scrolls formed around and made them more permanent, thereby extending the superlubricity.

This discovery could have many significant applications from turbines to hard drives, which is why the research team is already working to patent the hybrid material. There is still one issue to overcome though, and that is that water and humidity impairs the formation of the scrolls, thus limiting where the new lubricant can be used. With further research and computer modelling though, the researchers will hopefully find a solution.

Source: Argonne National Laboratory

Semiconductor Junctions Created Within 2D Materials

Category: Science & Technology
Posted: July 23, 2015 06:39AM
Author: Guest_Jim_*

The future of electronics will likely be thin, but not in the sense that it will fit better in your pocket. Instead there is a push to use two-dimensional crystals for building devices, instead of the current 3D crystals used. Now researchers at ORNL have devised a novel way to form arrays of arbitrary patterns within a 2D semiconductor crystal.

The researchers started with a single, nanometer-thick layer of molybdenum diselenide that then had silicon oxide applied to create the protective pattern. Next a beam of sulfur atoms was shot at the material. The sulfur atoms knock out and replace the selenium atoms wherever they strike, resulting in two semiconductor crystals separated by sharp junctions. Because the sulfur atoms were applied using pulsed laser deposition, it is possible to precisely control the ratio of selenium to sulfur, which influences the bandgap of the resulting hybrid material.

The next step for the researchers is to determine if this method can work on materials other than sulfur and selenium. This is very important as electronics require semiconductors, insulators, and metals.

Source: Oak Ridge National Laboratory

Method Created for Synthesizing Graphene on Silicon Chips

Category: Science & Technology
Posted: July 22, 2015 02:10PM
Author: Guest_Jim_*

Since its discovery, many researchers from around the world have been working to bring graphene to electronics, and we may be one giant step closer to realizing this. Researchers at Korea University have found a way to grow graphene on silicon, making it possible to integrate the material into silicon microelectronics.

Graphene was first discovered in 2004 and is the first 2D material we ever created. It is considered two dimensional because a single layer is just one atom thick, making it the thinnest material known to humanity. In addition to that distinction, it also possesses a number of extraordinary properties, including exceptionally high electron mobility, strength, and flexibility. These would make it ideal for electronics, but the normal means of producing it, chemical vapor deposition, is not compatible for silicon manufacturing. The Korean researchers' new method however is able to grow the graphene directly on silicon and silicon oxide by utilizing ion implantation. This works by accelerating carbon ions with an electric field into a layered surface of nickel, silicon dioxide, and silicon. The nickel acts as a catalyst for producing graphene during an activation annealing process.

Along with the ability to grow graphene directly on the silicon materials, this method also allows the properties of the graphene layers to be tuned, such as their thickness. Perhaps most importantly though is the fact that this method can produce graphene sheets with four-inch diameters, and it should be possible to scale them up to the size of silicon wafers. Now the researchers are working to lower the temperatures involved and to better control the thickness of the layers.

Source: EurekAlert!

Program Beats Humans at Recognizing Sketches

Category: Science & Technology
Posted: July 22, 2015 05:44AM
Author: Guest_Jim_*

Personally I am not afraid that a robot-apocalypse will happen, but when I see news like this, I cannot help but feel we should be working harder to maintain our dominance. A recent study from Queen Mary, University of London has determined that the program Sketch-a-Net is better at identifying sketches than people. The program had a success rate of 74.9%, beating humans at our 73.1% rate.

Sketch-a-Net is a deep neural network, which means the program emulates how our brains process information, but its success comes from more than that. The program uses information that is normally discarded, including the order the strokes were made in, and it turns out that information is helpful for identifying the subject. The program does need all help it can get too, due to the abstract nature of sketches, compared to photographs. Still it was able to distinguish the finer details of some sketches, including identifying four different bird variants.

With the growing use of touchscreens, Sketch-a-Net and similar programs will become ever more important as a means to interface with our devices. It could also find more professional uses, such as in police forensics for identifying persons in mugshots or CCTV footage from artists' impressions, as well as image retrieval systems.

Source: Queen Mary, University of London

Optical Absorbers Made Invisible to Other Frequencies

Category: Science & Technology
Posted: July 21, 2015 02:10PM
Author: Guest_Jim_*

The ability to manipulate electromagnetic radiation has been transformative for the world, as absorbers and sensors have enabled various technologies. Traditionally these absorbers also reflect light, so while they only absorb one frequency, they interfere with several. Researchers at Aalto University have found a solution to this problem and built a transparent absorber.

The new absorber contains an array of helical elements that are tuned to absorb only a specific frequency of light, so others are able to pass right through. This allows the absorber to be invisible to other frequencies, which will make it valuable for radio astronomy as well as stealth technologies. Regular consumer could also benefit from this discovery, as the absorber could be made into cellphone screens that capture cell signals without blocking Wi-Fi and other transmissions.

Source: Aalto University

How High-Frequency Electrons Behave in Graphene Discovered

Category: Science & Technology
Posted: July 21, 2015 06:16AM
Author: Guest_Jim_*

Everyone wants data to move faster and faster, which is easier to request than to achieve as new devices have to be created that can operate at these higher speeds. One avenue to creating these devices is to use graphene, but first its behavior at these high speeds has to be determined. Researchers at the Institute of Photonic Sciences have discovered that apparently the mechanics involved are not very complicated.

Graphene is an atom-thick sheet of carbon atoms with extraordinary optical and electrical properties that could make it ideal of optical communications. To test it the researchers applied electric fields to it that were oscillating in the terahertz range of frequencies. They found that the electrical current passing through the graphene at these ultrafast speeds were very efficiency converted to electron heat. This mirrors what happens in a hot gas, which is a fairly simple thermodynamic phenomenon. The better understanding this discovery brings with it should improve the performance of future electronic and optical graphene-based devices in the future, such as photodetectors and ultra-high speed transistors.

Source: The Institute of Photonic Sciences

Hybrid Crystal Made for Superior LEDs

Category: Science & Technology
Posted: July 20, 2015 02:20PM
Author: Guest_Jim_*

Getting the best of both worlds is a hard thing to achieve, in many cases, but not impossible if you work hard enough at it. This has been proven at the University of Toronto where researchers have combined colloidal quantum dots with perovskite to create a very efficient LED technology.

Quantum dots are sometimes referred to as designer molecules, because many of their properties, including the light they absorb and emit, can be tuned to the desired frequencies. Perovskites are a group of material that can be easily made in solution and have useful electrical properties, including good conductivity and resilience to defects. Combining these two crystals is not as easy as just mixing a couple solutions together because the ends of the crystals have to neatly connect. To achieve this, the researchers first grow a scaffold around the quantum dot, as the scaffold causes the perovskite to align the desired way for it to connect with the dot. The result is a hybrid crystal that efficiently feeds a quantum dot the energy needed to produce the desired frequency of light.

Possible applications for this work include infrared LEDs for night vision, biomedical imaging, and high speed communications. The applications will almost certainly not stop there though, especially as both of these materials are also of interest for absorbing light; not just emitting them.

Source: University of Toronto

Explaining Conductivity in Some Polymers

Category: Science & Technology
Posted: July 20, 2015 06:19AM
Author: Guest_Jim_*

A general rule of thumb is that metals conduct electricity and polymers do not, but like all rules, there are exceptions. Conjugated polymers are an example of this, as these plastics are electrically conductive, and for a long time it has been hard to explain why. Now researchers at MIT have found an answer that can lead to even better conductive polymers.

One of the main reasons conjugated polymers have been difficult to understand is that they exist in a middle-ground between crystalline and amorphous. There are well-ordered domains and chaotic regions throughout the material. According to the researchers, it is how the electrical current jumps across boundaries, from one domain to another that determines the conductivity. In bulk materials, the charge carriers can go in any direction, but in conjugated polymers they are limited to just the crystalline domains. The fewer options actually make the conduction more efficient, which is why thinner samples of the polymers work better.

So far the work has just been done with the conjugated polymer PEDOT, but it should be applicable to other conjugated polymers. As these materials, including PEDOT, can be conductive, transparent, flexible, and cheap to make many are looking at them for replacing materials like ITO, which is quite rigged and expensive but necessary for many applications.

Source: MIT

Finding a Speed Limit to Writable Optical Discs

Category: Science & Technology
Posted: July 17, 2015 02:17PM
Author: Guest_Jim_*

While Flash memory drives have certainly caused a decline in the use of rewriteable optical discs, they are still used and being improved upon. The question some have for these media is just how fast data can be written to the discs. Researchers at Caltech believe they have discovered something that will fundamentally limit the speed one can write to these discs, but it could also lead to new memory systems with advanced properties.

Rewritable optical discs, both DVDs and BDs, use phase change materials that lasers are able act on. By transitioning the material in a spot from crystalline to amorphous, the optical properties change and a bit of data can be stored. The process is a bit more involved than that, and to study it the researchers first fired a femtosecond laser at the material, triggering the change, and then a beam of electrons. The electrons would arrive later and based on how they scatter the researchers could determine the new structure of material. What they discovered is a previously unknown intermediary step, and because this step takes time to complete, it puts a speed limit on the process. So, even with ever faster lasers, you can only write to an optical disc so quickly.

This discovery is not exclusively bad news though, as the information it has given us about the limits of phase-change materials could influence future memory technologies that also use them. The next step for the research though is to study the process of turning the amorphous structure back into its crystalline form.

Source: California Institute of Technology

New Mold Allows for Advanced Silicon Nanostructures

Category: Science & Technology
Posted: July 17, 2015 06:06AM
Author: Guest_Jim_*

Whether for gelatin or toys, molds have been used by humans for a long time, and will continue to be used for producing precise structures. For making nanostructures though, molds have not been ideal because of the temperatures involved, but researchers at Cornell University have found a clever solution to the problem. This discovery could enable the creation of advanced, 3D silicon nanostructures.

To make precisely shaped molds for build nanostructures, the researchers turned to block co-polymers, which will self-assemble into the desired structure. The problem with this approach is that while the molds will be perfect, the temperature needed to melt silicon into it is far above what the mold can endure. The solution the researchers came up with was to change how the silicon is heated. Instead of heating the silicon to a liquid, and then pouring it into the mold, nanosecond laser pulses are used to create very short melt periods. These periods are so short that there is not enough time for the polymer mold to be damaged by the heat.

There are already methods of creating silicon nanostructures, but typically they result in amorphous or polycrystalline silicon. This method instead creates single-crystal silicon nanostructures, which could allow for special properties as it is the nanostructure, and not any defects, that will determine the final product's characteristics.

Source: Cornell University

Means of Growing Larger and Better Graphene Crystals Quickly Discovered

Category: Science & Technology
Posted: July 16, 2015 02:02PM
Author: Guest_Jim_*

Graphene is a material that could revolutionize several technologies, but like many possibilities, its potential is unimportant if we cannot make it. Producing high-quality graphene in large quantities has been a problem since it was first discovered. Researchers at the University of Oxford, however, have recently discovered a modification to chemical vapor deposition (CVD) that can make larger, better graphene very quickly.

Chemical vapor deposition works by releasing a hot gas of atoms into a vacuum chamber, and letting the atoms fall and collect on a substrate. For graphene, the substrate is often copper, but it can be other materials. What the Oxford researchers discovered is that if platinum with a platinum silicide layer on top is used, the resulting graphene crystals can be larger, of high quality, and made very quickly. This is all because platinum silicide has a lower melting point than either platinum or silica, so it can form a liquid on top of the platinum, creating a smooth surface as it fills in any rough spots. Without those rough spots, single graphene crystals have more room to grow in, without running into each other.

Normally CVD with a platinum substrate would produce graphene flakes about 0.08 millimeters in size, but this method created crystals 2 to 3 millimeters large. It also achieves this in just 15 minutes, as opposed to 19 hours for traditional CVD methods. As CVD can be scaled up to commercial levels already, it should be possible to scale this method up as well and potentially produce wafer-sized sheets.

Source: University of Oxford

White Graphene May Enable Advanced Heat Management

Category: Science & Technology
Posted: July 16, 2015 05:14AM
Author: Guest_Jim_*

Evacuating heat from electronics is important for good performance and preventing damage to the device. Efficiently removing heat from a computer chip can be difficult though, because while heat likes to flow along a plane, it does not like translating from one layer to another. A good example of this is stacked layers of graphene, but researchers at Rice University have found that white graphene may not have this issue.

White graphene is hexagonal boron nitride (h-BN) and shares the hexagonal structure as graphene, which is pure carbon. The two materials also share great thermal conductance, with phonons, the quanta for heat, being able to flow ballistically along them. Unlike graphene though, if you have a 3D structure of h-BN, heat will flow in all directions, instead of keeping to a single plane. This was discovered by modeling the flow of phonons in white graphene structures, where nanotubes connect the layers. While the junctions between the nanotubes and planes did slow down the phonons, they were still able to flow.

The researchers also discovered that they could control the flow of heat by manipulating the length and density of the nanotubes. This level of control could possibly lead to thermal switches or rectifiers that can create a preferred direction for the heat to flow, making it less likely to flow backwards, to the source.

Source: Rice University

New System Developed to Enable Data Transmission With Broadcast TV Channels

Category: Science & Technology
Posted: July 15, 2015 02:21PM
Author: Guest_Jim_*

The many frequencies of light in the electromagnetic spectrum each have their own advantages and disadvantages. For example, Wi-Fi signals use frequencies high enough to carry a lot of data very efficiently, but have very limited range and can be blocked by many objects and structures. Broadcast television transmissions are kind of the opposite, but could still be used to create 'super Wi-Fi' networks, and now researchers at Rice University have created a system that could make these networks easier to create and maintain.

Ultra high frequency, or UHF transmissions are able to carry for miles and pass through objects and structures like trees and buildings without much loss. This in comparison to Wi-Fi signals that may only go for a hundred feet under ideal conditions. The UHF part of the spectrum is primarily used by broadcast television, and to preserve those transmissions, data transmissions are limited to the frequencies that will not interfere with TV channels. In urban areas though, which are flooded with transmission, there might not be any of those frequencies available. The Rice researchers may have a solution though with their Wi-Fi in Active TV Channels (WATCH) system. This system can modify television broadcasts with signal-cancelling techniques to add data to the signal, so both data and TV can exist along the same channel. That is only half the system though, as WATCH still has to ensure it will not interfere with TV broadcasts. This was achieved in the Rice lab with smart-remote apps that informed WATCH whenever a channel was being watched, to stop manipulating the broadcast.

Compared to systems that relied on broadcasting on the frequencies that would not interfere with TV, WATCH was able to send six times the data. Of course for this to work on a large scale, WATCH will have to be able to gather information on the channels being watched in the area.

Source: Rice University

Scientists Discover Pentaquark Particle

Category: Science & Technology
Posted: July 15, 2015 06:40AM
Author: Guest_Jim_*

Back in 1964 the quark model was being developed to classify particles known as hadrons, which are comprised of quarks. The best known examples of hadrons are protons and neutrons, and both of those contain three quarks, but since the model was developed, scientists have been speculating if particles made of five quarks could exist. While analyzing background events in data from the Large Hadron Collider, researchers at Syracuse University unexpectedly discovered a pentaquark.

The actual intent of the study was to analyze the decay of a different particle, and a graduate student was given the undesirable task of examining a source of background events in the data. When the student came back though, he had a, "big smile on his face" because of the unexpected signal he detected. At this point he was directed to focus on that signal, instead of the original project. After some more work it was determined that the large source was actually a pentaquark consisting of four quarks and one antiquark. (More specifically two up quarks, one down quark, one charm quark, and one anti-charm quark.)

This discovery could lead to many more, including a better understanding of the protons and neutrons that make up the matter around us. Now the researchers are working to determine how the quarks are bound together within the new particle.

Source: National Science Foundation

Black Phosphorus Has Special Conductive Property That May Improve Future Transistors

Category: Science & Technology
Posted: July 14, 2015 02:25PM
Author: Guest_Jim_*

Many companies and institutions are working to bring basic electronic components to ever smaller sizes, with the ultimate goal of reaching the atomic scale. This work is being done because at these smaller scales, transistors can operate more efficiently, the thinner they are. Now researchers at McGill University and Université de Montréal have discovered that electrons in black phosphorus will move like the material is 2D, even if it is not.

The material black phosphorus can be separated down to single atomic layers called phosphorene, similar to how graphite can have layers removed to create graphene. While graphene is a conductor though, phosphorene is a natural semiconductor, like black phosphorus. By making transistors out of black phosphorus then, it should be possible to eventually scale down to phosphorene. When studying how electrons move in a black phosphorus transistor though, they discovered that the current moves like it is a 2D sheet, even though the material is three-dimensional.

Currently black phosphorus cannot be produced on a large scale, but this discovery could help in that area.

Source: McGill University

Bringing Computing Elements to a New Bacterium

Category: Science & Technology
Posted: July 14, 2015 06:17AM
Author: Guest_Jim_*

While it may sound too weird to be real, many people are working on organic computers that use bacteria and single-cell organisms to process information. Typically the research in this area uses a few model bacteria, like E. coli, which are very well understood. Researchers at MIT however, have successfully built basic computing elements with a different bacterium found in the human gut.

Bacteroides thetaiotaomicron is already found in many people and at levels large enough that a stable colony could be formed. What the researchers have done is program the gene expression within the bacteria to give it sensors. These sensors can then trigger certain genes to turn on or off, making it possible to monitor for certain events, such as bleeding in the stomach or inflammation. It could potentially lead to a means to and treat illnesses such as colon cancer and immune disorders.

So far the researchers have demonstrated the programmed bacteria can function within mice and now they plan to expand the potential applications for this and other gut bacteria. It is possible this research could lead to programmed microbes in other parts of the body.

Source: MIT

Using Flash Memory Instead of RAM to Reduce Energy Use

Category: Science & Technology
Posted: July 13, 2015 02:32PM
Author: Guest_Jim_*

For someone using a PC, RAM is an essential component that significantly impacts performance and stability. For data centers with numerous servers or supercomputers though, RAM can also be a huge use of power. Now researchers at MIT have found a way to potentially remove that cost by using Flash memory in a rather novel way.

Because RAM is a volatile memory technology, it has to constantly rewrite data to itself, which takes a lot of power over long periods of time. Flash memory however, is nonvolatile so no rewriting is needed, and thus it uses far less energy, but it is also slower. What the MIT researchers have done is design a network of servers that are based on Flash memory that can still match servers based on the faster RAM. This is accomplished by leveraging the computational power of the chips controlling the Flash memory. The researchers have these chips preprocessing data before passing it to the servers, creating a more efficient, distributed computation system.

For their prototype system, the researchers connected 20 servers to an array of field-programmable gate arrays (FPGAs), which can have their circuits reprogrammed, and the FPGAs connected to half-terabyte Flash chips. Though FPGAs are a bit too expensive to be used on a large scale, their ability to be made into specialized accelerators for running various algorithms could make them invaluable for this system.

Source: MIT

Better Cooling with Graphene Films

Category: Science & Technology
Posted: July 13, 2015 06:05AM
Author: Guest_Jim_*

Heat is a big problem for our electronics that only increases as you scale things up, to the point that half the power used by some server farms is just for cooling. Naturally then, many efforts are being made to more efficiently cool electronics, including some involving graphene. The issue graphene though has been that thicker films, which conduct heat better, will detach from chips more easily, but researchers at Chalmers University of Technology have found a solution.

Graphene is considered a wonder material and has many special properties, including great conductivity and a single layer being two dimensional. The issue with graphene here is that thicker films are better at conducting heat away, but only the ultrathin films will adhere to the silicon chips using van der Waals forces, a relatively weak force. Making the film thicker causes the bonds to break, making the film useless for conducting heat away. The Chalmers solution though is to functionalize the graphene surface by adding a molecule to it that will create stronger, covalent bonds with the silicon. These bonds can easily support the weight of a thicker graphene film.

A graphene film just 20 micrometers thick can have four times the thermal conductivity of copper, so imagine the possibilities of that interface between a chip and larger cooling system. Integrating graphene onto the chip could also open the doors to other uses, like adding LEDs, lasers, and other components to improve cooling even more.

Source: Chalmers University of Technology

Bringing One Example of Quantum Mechanics to the Larger World

Category: Science & Technology
Posted: July 10, 2015 03:04PM
Author: Guest_Jim_*

Quantum mechanics allows for some odd things to happen, like materials that block the flow of electrons within their volume, but are conductors over their surfaces. These topological insulators could have a variety of uses in future technologies, especially as we come to better understand them. Now researchers at ETH Zurich have succeeded in recreating this effect in the classical realm with an array of pendulums, and it too could have uses, including sound and vibration insulation.

Normally one would expect the math beyond quantum systems to be only relevant in quantum mechanics. The Zurich researchers realized, however, that by rearranging the formulae for topological insulators, they would resemble those for an array of swinging pendulums, which is a well-understood system. From this, the researchers got to work constructing an array of 270 pendulums in a rectangular lattice, connected by springs, coupling them all together. Only two of these pendulums were powered, and thus could have their frequency and strength controlled. With the correct frequency, the researchers discovered what they were hoping for; the outer pendulums could be made to swing in rhythm while the inner pendulums hung still. This is like a topological insulator, where electrons will flow over the surface, but will not pass through the center.

Not only were the researchers able to recreate this quantum mechanical phenomenon, but it also turned out to be very robust, as it could survive the array being disordered and some even being removed. Now the researchers are working to shrink the system from the half-meter long, half kilogram pendulums to something without pendulums, and just centimeters in size.

Source: ETH Zurich

Making Wakes of Light

Category: Science & Technology
Posted: July 10, 2015 06:00AM
Author: Guest_Jim_*

We are all familiar with wakes in one form or another, likes those made in a body of water, or the sonic booms of supersonic aircraft. Cherenkov radiation you are probably less familiar with, but is also a kind of wake, but involves light instead of water or sound. Now researchers at Harvard University have gone a made the interesting and impressive step of creating and manipulating wakes of light on the surface of a metal.

Cherenkov radiation is created when a charged particles travels faster than the phase velocity of light in a medium. The speed of light in a vacuum may be the Universe's speed limit, but when light is in a medium, like air or water, it propagates slower, leaving room for particles to travel faster, without breaking the ultimate limit. The researchers managed to recreate this with plasmons on the surface of a metal, with the charge moving along a one-dimensional metamaterial. The researchers found they could manipulate the wake, making it go in different directions, and even go backwards, by controlling the angle the light was shining on the metamaterial.

This research could potentially be used to study wake physics in new ways, and from that discover new means of controlling light and plasmons. Plasmons are already seen as a path to advanced nano-optics that will allow for technologies not currently possible.

Source: Harvard University

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