Science & Technology News (479)
Posted: July 30, 2014 02:09PM
For about as long as I can remember, I have worn glasses that have corrected my vision very well. Not everyone is so lucky though, with some people actually requiring glasses or contact lenses to view displays. Researchers at the University of California, Berkeley have recently developed a display technology that could help these people by shifting the vision correcting to the display.
Vision correcting displays have been developed by many groups over the years by using multilayer displays and light field displays. These do not always correct the images perfectly though or can produce a sharp but low contrast image. What the Berkeley researchers have created is a light field display that takes advantage of pre-filtering to create a sharp image, without sacrificing contrast. Basically the image of the basic display is manipulated mathematically so that a pinhole screen on top of it will work with the user's eyes to produce a sharp image. The key to this work is that mathematical pre-filtering. To anyone other than that user though, the image will look quite bad.
By adding eye-tracking technology to this system, the researchers hope to address the issue of head positioning, so that no matter how the user looks at the screen, the image will be sharp. Already though they know their method can be applied to help with a variety of complex visual problems.
Posted: July 30, 2014 09:31AM
Batteries are a big deal today as without them we could not have cellphones, laptops, and many other advanced pieces of technologies. While batteries have enabled these technologies, they also limit them by needing to be recharged for continued use. Researchers at Stanford University have recently made a discovery that could lead to batteries with substantially greater lifespans than what you can find today.
Lithium-ion batteries are very popular today because they are rechargeable and can store a great deal of energy. Within each of these batteries is an electrolyte, containing lithium ions, an anode and a cathode, likely made of graphite of silicon. While those materials work well for the anode, researchers have known for some time that lithium would make a better anode, but lithium poses two challenges. One is that as a lithium anode would absorb lithium ions from the electrolyte, the anode would swell to such a size that it would fracture, which could lead to a short circuit as lithium ions escape from the fractures, forming dendrites. The other is that lithium is so reactive that it would use up the electrolyte and shorten the battery's lifespan. To solve both these issues, the Stanford researchers developed domes of carbon to surround the lithium anode, forming a nanosphere. As the nanospheres are flexible, they will survive the swelling but block dendrites from forming, and because they are not chemically reactive, the lithium ions will not chemically react with the anode.
Potentially a lithium anode battery could enable phones to have double or triple their current lifespan, or drop the cost of electric vehicles by requiring fewer batteries to achieve a three hundred mile range. Currently though, the cycling efficiency of the battery is not high enough for commercial use yet, but you can believe many are working to get it there.
Source: Stanford University
Posted: July 30, 2014 05:57AM
Natural gas and its components are valuable resources, but are tricky to work with because they are gases. Refining and converting the hydrocarbons into liquid fuels can be done, making storage and transport easier, but the processes involved require high pressures and temperatures. Researchers at Berkeley Lab and many other institutions have recently developed a proof-of-principle catalyst that drops the requirements, and could improve access to these liquid fuels.
Natural gas is comprised of many hydrocarbons, including methane and ethane, the latter of which can be converted into ethanol. That conversion process is expensive due to the 200-300 ºC temperature requirement, so the researchers have been working on a catalyst to ease the process. What they have developed is a metal-organic-framework (MOF) with iron attached, forming Fe-MOF-74. The structure of MOFs is like a cage, which enables them to act as a filter for other molecules, and have a large amount of surface area to absorb gases and liquids. The iron atoms inside the cages act as a catalyst for producing ethanol from ethane, reducing the temperature requirement to just 75 ºC.
With such a reduction in temperature, this discovery could drastically reduce the cost of converting natural gas into liquid fuels. Those fuels, which are generally clean burning, can then be stored and distributed more easily.
Source: Berkeley Lab
Posted: July 29, 2014 04:29PM
Magnets have quite a number of uses, from entertaining and educating students to storing data. Magnetism itself is the result of the magnetic moments, or spins of particles in a material aligning. Researchers at MIT have recently found a phenomenon to do with magnons that can be used to cool magnets, remotely by a magnetic field.
Magnons are quasiparticles representing the collective spins of particles within a magnet. These quasiparticles are able to move through a magnetic when exposed to a magnetic field gradient. What the MIT researchers realized is that when the magnons move, they take heat with them, cooling part of the magnet. From this idea they built a theoretical model based on the Boltzmann transport equation, which has to do with electron transport in thermoelectrics, and plugged in numbers found in previous research papers. The results suggest that though small, the effect does create a cooling effect from a moderate magnetic field gradient.
Currently this work is purely theoretical, so we cannot expect to be cooling our electronics with it any time soon. It will likely first find a use in cryogenic systems, as the effect is more pronounced at low temperatures.
Posted: July 29, 2014 11:25AM
Chemical sensors are very valuable tools for many situations, including protecting against bombs at airports and other public areas. Sometimes the sensors are expensive, manmade devices, requiring well-trained users, and other times trained dogs are used. Researchers at Tel Aviv University though have developed a new sensor that is cheap and easy to operate, while being significantly better than the alternatives.
The device the researchers built is a tiny chip with clusters of transistors on it. These transistors have been designed so that when a single molecule contacts them, it binds to them and affects their conductance. This change makes it possible to detect and even identify the molecule caught from the air, all in real-time. The chip is so sensitive to the molecules, that it can detect some in concentrations approaching parts-per-quadrillion, which is orders of magnitude better than other chemical sensors, and even dogs noses.
Thus far the prototype sensor has been tested against commercial blasting and military explosives, as well as some improvised explosive materials. By being faster, cheaper, and giving users the ability to identify detected chemicals, this sensor could go a long way to keeping people safe.
Posted: July 29, 2014 06:13AM
Information can be very overwhelming for humans, which is part of the reason computers were developed, but even they can struggle. Massive datasets can slow even the best computers, and when results of some analysis are needed urgently, that can be a problem. Researchers at MIT though have developed an algorithm that can intelligently predict what information in a dataset will be useful, without the slow task of directly analyzing it.
To achieve this, the researchers turned to a probabilistic graphical model, which abstracts data into nodes, with connecting edges representing relationships between the nodes. By knowing the strength of the connections, one can quickly target what data is most valuable, and focus on them. Determining the strength can be complicated if nodes are connected by more than one path, creating a loop. To address this, the algorithm creates a spanning tree that dispenses with the loops and turns to Gaussian distributions to avoid distortion. It turns out that the probabilities represented by the graph are Gaussian, which means they can be described by their average value and variance. The uncertainty of the problem can be determined from the variance, but that does not require actually processing the data.
What all of this adds up to is a way to identify the most important and useful information in a dataset, without having to analyze the dataset. This results in the process being significantly faster, which could be very important if, for example, it is weather data being used to predict a storm's path that is being analyzed.
Posted: July 28, 2014 02:58PM
Superconductivity is a phenomenon many in the world have been waiting anxiously for, but achieving it is difficult. Typically the materials that can become superconducting must be cooled to very low temperatures, but the hope is to one day find or design one that would work at room temperatures. Researchers at the University of California, San Diego have recently discovered an artificial crystal structure that should support superconductivity, and the principle behind it.
The structure the researchers describe is comprised of alternating layers of atomically thick layers of semiconductor and insulator. Specifically they describe the molybdenum disulfide as the two-atom thick semiconductor, with boron nitride being the few-atom thick insulator separating and cladding the semiconductor. When an electric field is applied to this structure, electrons and holes, the positively charged areas left behind by electrons, collect in the different semiconductor layers. Despite the separation, the electrons and holes are still bounded, forming indirect excitons. At a certain temperature, these excitons will achieve the coherent state of superfluidity, meaning that they will form a gas lacking any viscosity. This will also cause the phenomenon known as counterflow superconductivity.
What this all translates to is a blueprint for creating structures that become superconducting at a specific temperature. Presently that temperature is predicted to rest near that of other high-temperature superconductors, which is still pretty cold. As the blueprint can be applied to other materials though, it could lead to new understanding of superconductivity and other quantum phenomena.
Posted: July 28, 2014 01:23PM
In 1985 it was discovered that carbon atoms can be arranged into a ball-like structure, dubbed buckyballs. This started scientists looking for other special carbon structures, as well as a search to determine if other elements can form similar structures. Researchers at Brown University have recently found that boron, carbon's neighbor, can, but it does have some important differences.
Buckyballs, or fullerenes are comprised of 60 carbon atoms, bound together in pentagons and hexagons. As boron has one less electron to bound with, this structure cannot be duplicated, but theoretically a cluster of 40 boron atoms could take on a different structure. Exactly what structure that would be, required extensive modelling by supercomputers, which provided binding energies for the different possible structures. These energies can act as fingerprints for molecular structures, so once the researchers produced the 40 atom clusters, they could measure what the structure is. To make the clusters, the researchers hit bulk boron with lasers, releasing a boron vapor that they then cooled with a helium jet. After isolating the clusters consisting of just 40 atoms, the researchers used another laser burst to get the binding energy.
The results showed that the boron clusters took on one of two structures, with one being like a sphere. Instead of being made of pentagons and hexagons like buckyballs, borospherene is comprised of triangles with six and seven-sided rings, with some atoms sticking out, making the structure less-than spherical. As it has only just been discovered, applications for borospherene are still unknown, though it could have potential for storing hydrogen.
Source: Brown University
Posted: July 28, 2014 06:41AM
Waste heat is a problem for many systems, including car engines, power plants, and even solar cells. With solar cells the problem is not just the loss of energy as heat, but that increased temperatures decrease performance. As reported in the Optical Society's new Optica journal, researchers have found a new way to significantly cool solar cells, passively.
Sunlight is comprised of much more than just the visible light we see, and that solar cells convert to electricity. It also contains infrared light, which efficiently carries heat, and it will dump that heat onto solar panels, causing them to heat up to as much as 55 ºC (130 ºF). As even a single degree Celsius can drop the efficiency of a solar cell by half a percent, and 18 ºF can double the aging rate of a cell, such high temperatures are a problem. To address this, the researchers turned to silica glass, which is transparent to visible light, but can be shaped to manipulate infrared light. They tested both a flat layer of silica on a solar panel and a surface covered in cones and pyramids just microns in size. The more complicated surface performed significantly better than the flat surface, and nearly as well as the ideal design would.
What the complex design does is refract and redirect the infrared radiation away from the solar cell, keeping it cool. The researchers are now doing more experiments on the design and will be demonstrating their cooling scheme in an outdoor environment next.
Source: The Optical Society
Posted: July 25, 2014 02:24PM
Scientific discoveries that enhance and augment another are not limited to being discovered after the technology they will improve. As reported by Springer, researchers have found a new way to couple quantum dot triples, resulting in improved performance. This could easily translate to faster quantum computers, when those are created, assuming they use quantum dots.
Quantum dots are man-made semiconductor crystals that can have their properties tuned to match many situations. In this case, the situation is to couple three of them together, but not as is normally done. The three quantum dots still have inner electrons entangled, which protect the electrons from interference, but one of them is coupled with electrodes. Though it is inner electrons that are entangled, the electrical resistance of the conducting electrons can also be affected. By measuring changes in electrical conductance, it is possible to observe when the quantum dot shifts between an entangled and disentangled quantum phase; a transition they can induce.
The result of this research is a faster means to measure the change in the quantum dots, as previous methods required looking for a jump in entropy and spin susceptibility. Before one has even been built, quantum computers are already getting an upgrade.
Posted: July 25, 2014 05:15AM
Lasers are among the more important technological discoveries of the twentieth century, and are one technology that may never stop having a use. Of course for that to continue to be the case, advances must be made to improve lasers, such as how high-frequency lasers enable denser optical data storage systems. Thanks to researchers at the MIT Lincoln Laboratory spinout TeraDiode, we have a new laser system that could increase industrial use of the technology.
There are many avenues to produce laser light, with early lasers stimulating gases and more modern lasers using diodes. While the diode lasers can be significantly more efficient that gas-based lasers, diodes typically do not offer the power gases do. This has kept diode lasers from being used to cut and weld metals, but TeraDiode has found a solution with their TeraBlade system. By using a transform lens, a diffraction grating, and an output lens, the system is able to take the light from bars of diode lasers, and superimpose the light into a single beam.
The TeraBlade beam approximately matches the power of other industrial lasers at 2600 megawatts per square centimeter per steradian, but at 40% efficiency. Other industrial lasers are only 20-30% efficient, and can take up more room, so it is not surprising that TeraDiode is already finding customers in Japan and Europe.
Posted: July 24, 2014 01:53PM
Anyone who has tried to look at a phone, tablet, or laptop screen in Sunlight knows just how frustrating the glare and reflections of the screen can be. This makes it rather unsurprising that so many products exist to counter the problems, but some do not work well with glass. Researchers at the Institute of Photonic Sciences and Corning Incorporated though have developed a new method to make glass surfaces anti-glare, anti-reflective, and even hydrophobic.
Today you can go out and get anti-glare filters and films for your devices, and some have nanostructures on top of them, to add anti-reflective properties. These structures do not work well on glass, so the researchers worked on the glass directly. By roughening the surface of glass at a very fine scale, it can be made anti-glare without sacrificing transparency. Etching in nano-sized teeth makes it anti-reflective, and as it turns out, the resulting surface features made the glass water repellent, like a lotus leaf.
This method to affect the properties of the glass is inexpensive and can be scaled up for industry use. Before that will happen though, more research needs to be done, in part to determine how well the features endure touchscreen use.
Source: American Chemical Society
Posted: July 24, 2014 05:57AM
Information can be stored in many ways, and for many systems the density it is stored at is very important. There can be limits to the density though, such as with the wavelength of light. By using a plasmonic film though, researchers at the University of Illinois have recorded optical information at sub-wavelength scale, and in real time.
The plasmonic film is actually an array of gold, pillar-bowtie nanoantennas (pBNAs) that reacts to laser light. The reaction is analogous to how photographic film behaves when exposed to light, but the effect occurs in real time, and does more than store an image. When exposed to laser light, the pBNAs actually create optofluidic channels without walls, allowing the researchers to affect the trajectory of particles in a solution. Other optofluidic systems have been made that achieve the same goal, but do have physical walls.
When the researchers tested it, the bit size was around 425 nm, which is directly related to the spacing of the antennas. If this were applied to an optical disc that would be around 28.6 GB of data, but by modifying the spacing of the array and the antennas, it could be scaled up to 75 GB a disk. That is of course only considering data storage applications, but this discovery could have many other photonic uses.
Posted: July 18, 2014 06:06AM
Most every time you visit a website, a host of servers somewhere have to run the right operations to gather the data you need, and then send it to you. As some websites use large data centers, with the servers working for you spread out, the latency between the servers can impact performance. Currently decentralized communication protocols are used to manage communication in a data center, but researchers at MIT have recently designed a new, centralized system that can offer better performance.
Decentralized protocols enable each node in a network to send and receive information without instruction. Provided the routers transmitting the information do not get overwhelmed, this approach can work well, but in some data centers they are being overwhelmed, causing large queues to form, leading to congestion. One would not expect a solution to come from sending requests to a central arbiter server, which takes 40 microseconds, but the MIT, Fastpass system not only reduces the congestion, but does so by a very significant amount. The Fastpass system takes advantage of parallel programming to divide the work of scheduling communication across multiple cores. The first core looks at the pending requests, schedules one for a slot, and then passes to the next core all of the requests involving either the source or destination node of the schedule request.
The researchers found that by using this approach, the Fastpass system is able to handle a network transmitting at 2.2 terabits per second, with just eight cores. In experiments to be presented in August, the researchers will show that Fastpass cut the average queue length in a Facebook data center by 99.6%, and the average latency from 3.56 microseconds to 0.23 microseconds.
Posted: July 17, 2014 03:12PM
According to Moore's Law, the number of transistors that can fit on a microprocessor will double roughly every two years. While it has been holding true for some time now, the technology has rapidly been approaching a barrier that could bring everything to a halt. One part of the barrier has been the photoresist used to etch circuitry onto silicon, but now a partnership between Berkeley Lab and Intel has found what could be its replacement.
To create the small and intricate circuitry in computer chips, manufacturers start with a wafer of silicon and coat it with a photoresist. Using a UV light source, an image of the circuitry is burned onto the photoresist, changing its properties where the light hits. A solvent is then used to wash away the unwanted photoresist, enabling selective deposition to build the circuitry up. The photoresist currently used was first developed to work with deep UV light, which has wavelengths between 248 and 193 nm, but manufacturers want to transition to using extreme UV, which can reach down to 13.5 nm for its wavelength. Due to the complexity of the photoresist compound, many have avoided developing a replacement as the risk could be so great.
A new photoresist is going to be needed to reach the smaller sizes chip makers want though, and some work has been done to that end. The Berkeley researchers decided to combine two promising photoresists and were surprised to find the mixture actually keeps the properties of its parts. One photoresist had great stability, but took long exposure times to achieve it, while the other was highly sensitive, but less mechanically stable. More work needs to be done to optimize the mixture, but the researchers believe it could reach manufacturing lines by 2017.
Source: Berkeley Lab
Posted: July 17, 2014 06:54AM
Many interesting scientific discoveries have come from unexpected sources. Last year it was discovered at MIT that when water droplets leap from a superhydrophobic material, they can gain an electrical charge. Now MIT researchers have found a way to use this phenomenon to produce useable electricity.
Superhydrophobic materials are characterized by the fact that water hates to touch them, which has made them interesting for use in condensers. Water will still condense onto the hydrophobic material, and by leaping off of it, frees up space for more water to condense. When the researchers found that these leaping droplets will be charged, they added oppositely charged plates to condensers, to improve efficiency. By making the plate superhydrophilic instead, and connecting it to the superhydrophobic plate, the MIT researchers found they had created an electrical circuit.
So far tests have only produced 15 picowatts of power per square centimeter, but the researchers believe the device could be easily tuned to 1 microwatt per square centimeter, which is comparable to other devices that harvest ambient energy. While that is not much power, the remote systems that would be powered by this technology, do not necessarily need much.
Posted: July 16, 2014 02:04PM
The ability to controllably route information is fundamental to electronic computers, and is similarly necessary for future quantum computers. Researchers at the Weizmann Institute of Science have recently created the world's first photonic router, capable of routing photons based on photonic signals.
The router works by switching the state of an atom caught in a trap. In one state, the atom will allow photons coming from the right to pass on, but will reflect photons coming from the left. When it reflects a photon though, its state will flip and now photons from the left will pass on while photons from the right are reflected, and trigger another switch. The photons from the right and left are coming from optical fibers, which have been coupled to ultra-high quality, miniature optical resonators.
As photons are capable of carrying quantum information and relatively protected from interactions that would destroy the information, this system could prove invaluable for quantum computers. Next the researchers want to work on other kinds of devices, such as quantum memory or logic gates, and see if they too can be made to function only with photons.
Source: Weizmann Institute of Science
Posted: July 16, 2014 06:07AM
For any website with video content, views are critical for not only sharing the content but generating ad revenue. Obviously the videos must be interesting, but so too must their thumbnails, to encourage people to click and watch. Neon Labs, a Carnegie Mellon University startup company has recently signed an agreement with IGN Entertainment, so the startup's thumbnail-selection software can find the best images.
Researchers from many institutions have found that our preferences can be influenced by visual perception, without our knowing. The Neon Labs software applies this knowledge to scan a video stream for the thumbnail that will encourage the most engagement. In some cases the algorithms can lead to 100% more engagement over the images humans may select. For IGN though, the clickability increased by 30%, on average, which is still impressive. It also took over the significant amount of work required to select thumbnails, making it a "huge win" for the company.
Source: Carnegie Mellon University
Posted: July 15, 2014 02:00PM
For decades we have been using electronics that operate on the charge of electrons, and while the technology has been serving us very well, it is approaching its limits. A potential replacement is spintronics, which utilize another property of electrons known as spin and spin current. Among the many benefits of spintronics is the possibility of great speed, and now researchers at the University of Illinois have found a way to create spin currents at that great speed.
A normal electrical current, like those used in electronics, is made of electrons with spins pointing in random directions. A spin current is formed when those spins line up, but causing that to happen is not easy. Normally it requires creating a voltage difference across a structure, but the Illinois researchers were able to produce a current using heat instead. Within a metallic ferromagnet are three energy reservoirs, and by creating a temperature difference between two of them, the researchers were able to generate a spin current. The two reservoirs are electrons and magnons, and the temperature difference caused the spin angular momentum of the magnons to be transported to the electrons.
Unlike the more traditional means of producing a spin current, this thermally-driven method created the current in trillionths of a second, or picoseconds. Naturally this great speed would be very welcome for fast magnetic memory devices.
Source: University of Illinois
Posted: July 15, 2014 06:54AM
Though flash-based SSDs may be replacing magnetic hard drives in many of our machines, the traditional HDD is still a common piece of computer hardware. The technology is approaching a limit however, as bits can only be so small before writing one bit risks disrupting those around it. Researchers at Eindhoven University of Technology have developed a more efficient way of writing magnetic bits though, that could increase speeds tremendously.
Typically flipping a bit requires a local magnetic field, causing the magnetic properties of the hard disk material to change from one state to another. The two states can be read as either zero or one, for binary data. Instead of using a magnetic field though, the Eindhoven researchers use ultrafast lasers to trigger a spin current. Spin is an intrinsic property of many particles, including electrons, and its direction determines the direction of the particle's magnetic field. A spin current is just a flow of electrons all with the same spin. To produce the current, the researchers fired ultrafast laser pulses at a material made of two magnetic layers, with a neutral layer in between. When the laser strikes the top layer, the electrons in it try to move through the material, and take with them the spin of the top later. This spin then exerts a force on the bottom layer, causing it to flip its magnetic state.
The changes in magnetic state of the bottom layer take around 100 femtoseconds, which is approximately 1000 times faster than modern technology can achieve. While that is definitely impressive for write speeds, because of the use of lasers, this technology could also be used in future optical computers, for data storage.
Posted: July 14, 2014 02:04PM
Flash memory has impacted many people and technologies, thanks to its speed, stability, and density. While it may be a champion memory technology at the moment, there are new technologies looking to supplant it. Among these is Resistive Random Access Memory (RRAM), which researchers at Rice University have recently made more appealing to the industry.
This new memory type works by putting a resistive material between two wires. When a great enough voltage is applied to the wires, the electricity will form a conducting path through the normally resisting material. Those pathways do not need to be permanent though, allowing RRAM to be rewriteable, and because of how small its cells can be, it can have 50 times the data density of flash. Though many materials can be used for RRAM, the Rice researchers are working with silicon dioxide, which is already a very well understood material, and one with many advantages over its competitors. These include the ability to be manufactured at room temperature, a high on-off ratio, low power consumption, and nine-bit capacity per cell. The recent research has increased silicon dioxide's potential by revealing that porous silicon dioxide requires thirteen times less energy to create pathways in and does not require special edge fabrication methods.
Some predict that RRAM could start coming to market and competing with flash in a few years, thanks to its greater speed and density. Now that it has been shown that a device edge structure is not needed, companies have already started trying to license the technology.
Source: Rice University
Posted: July 14, 2014 06:53AM
For probably as long as humans have been able to look up and see other planets, we have been wondering how the planets came to be. For Venus and Earth it is generally accepted that they formed as the result of smaller objects colliding and coalescing into the planets we know today, but what about Mercury? The nearest planet to the Sun has some curious properties to it, including a very high concentration of iron, and now researchers at Arizona State University have an explanation for why.
Of the terrestrial planets in the Solar System, Mercury has the greatest concentration of metallic iron, with 65% of its mass being its iron core, compared to Earth's core making up 32% of its total mass. Also Mercury has a great many volatiles on it, such as water, lead, and sulfur, even compared to the Moon. This is particularly confusing as it indicates that the planet likely did not suffer a giant impact in the past, even though such an event would explain its lack of a mantle. The Arizona researchers though suggest that while Mercury never suffered a giant impact, like Earth and Venus did, it likely suffered many smaller, glancing impacts, which stripped off its core little by little.
The idea of glancing impacts is not new, but had always been discounted before, as the belief was that the object would be caught gravitationally, and ultimate be devoured by the larger body; proto-Venus or proto-Earth. According to the new theory and model though, glancing blows do not necessarily doom a body, and multiple could actually help preserve the dominate survivor of these impacts.
Source: Arizona State University
Posted: July 11, 2014 06:01AM
According to some examples of science fiction, one day we will have the ability to read minds through technology, for better or worse. According to researchers at Cornell University, at least emotions may not be as hard to read as we thought. Analysis has revealed what appears to be the existence of a standard code for processing emotions.
Traditionally it has been believed that the brain processes emotions in certain regions, and that a positive or negative emotion depends on the region. This new research indicates a very different process that does partially rely on sensory experience. Subjects were presented with pictures and tastes while undergoing functional neuroimaging. The imaging revealed that the brain generates special, sensory-dependent codes in the appropriate regions for the senses, and in the orbitofrontal cortices. This indicates that the emotional experience is not limited to certain brain regions and may even by linked to perception.
The subjects were also asked to score their emotional responses to what was presented to them. The researchers found that those who reported similar scores also had similar activity patterns in the orbitofrontal cortices, which suggests that the code used there for experiences of pleasure and displeasure, may be shared across people.
Source: Cornell University
Posted: July 10, 2014 03:08PM
Adhesives are very useful tools, whether we are putting paintings or electronics on a surface, but sometimes we do not want to leave a residue behind or want to remove the object later. One possible solution is to apply the physics that allow geckos to walk upside-down on seemingly smooth surfaces. Researchers at Linköping University however have found that the physics involved are not permanent, and so may not be the best choice for all applications.
All molecules and atoms are attracted to each other by van der Waals forces. These are weak forces though, so you cannot expect to climb a wall just by pressing your hands against it. Geckos and spiders however have evolved special hairs that are able to get so close to a surface and with enough surface area that the van der Waals forces are able to resist gravity. The Linköping researchers decided to look into this more deeply and found that van der Waals forces do not hold indefinitely. Both the surface and the object suffer very small vibrations from molecules moving, and for the most part these are insignificant. Eventually though, these movements will fall in sync between the object and surface, which will cause them to detach from each other.
As the researchers point out, this is not a problem for geckos and other living, moving objects, but would mean you would not want to hang up anything relying on van der Waals for too long.
Source: Linköping University
Posted: July 10, 2014 07:11AM
Nobody enjoys sitting at red lights, waiting for the signal to change, but finding the optimal timing is difficult and complex. Models do exist that can achieve amazing resolution, but these come at the cost of efficiency and sometimes larger accuracy. Researchers at MIT though are proposing a new method that could optimize timings better than these models, cutting down on wait times significantly.
Typically cities will time their traffic lights by focusing on the primary arteries and just optimizing the times along those routes. This approach has the limitation of not considering the ripple effects on other roads, such as from drivers taking an alternate route, to avoid lights. As these models will consider individual driver behavior, it becomes prohibitively complex to grow them to consider all of these effects. The MIT researchers however found an efficient way to arrive at the optimal timings while avoiding the complexity. It starts with the high resolution technique to propose timings and then uses a lower resolution model to look at traffic flow.
To test this new approach, the researchers considered the traffic of Lausanne, Switzerland. The timings it produced resulted in a 22% reduction in average wait time for the city, according to simulations. Next the researchers want to expand the model to be able to adapt to changing traffic conditions.
Posted: July 9, 2014 03:09PM
Many technologies depend on others in order to operate and advance. What may be the best example of such a supporting technology is the battery, and without some new discoveries, it may be limiting future mobile devices. Researchers at the University of California, Riverside though have developed a new means to produce anodes for lithium ion batteries cheaply, while still improving performance.
Traditionally lithium ion batteries have used graphite anodes, as the carbon material has the needed electrical properties and resilience. Silicon would be a better material for its electrical properties, but it is hard to produce in large quantities and is less resilient. The Riverside researchers had a new idea for producing silicon anodes after one of them looked at a handful of beach sand. Silicon dioxide, or quartz, is a primary component of many sands, and the researchers realized that it could be purified to pure silicon by heating it with salt and magnesium. This process of removing the oxygen produces very porous silicon nanoparticles, and that porosity is valuable for battery anodes, by increasing the surface area that electrons can access.
Thanks to the nano-silicon’s porosity, batteries built using it as the anode could have triple the lifespan, or better, than conventional batteries. So far the researchers have produced coin-sized batteries, but are trying to move to larger sizes, likes those in cellphones.
Posted: July 9, 2014 06:12AM
For many experiments and studies, scientists will consider ideal conditions to keep things simple. As reality is not ideal, sometimes adaptations will be made to the research to approach reality, and make the results more informative. Researchers at the University of Pennsylvania however are suggesting that for many materials, instead of starting with a perfect crystal and adding defects, it would be better to start with an anticrystal, and add order.
Crystals are materials with well-ordered internal structures, whereas anticrystals are the opposite and are completely disordered. Realistic materials would be on the spectrum between these two extremes, and everything has many properties determined by their internal structures. According to the Pennsylvania researchers, many materials would be better described from the starting point of anticrystals with added order, than perfect crystals with added disorder. The researchers liken it to a deck of cards shuffled once being closer to a totally shuffled deck, than a totally ordered one.
As many properties of materials are determined by their structures, this research could have many great impacts, including leading to better plastics, glasses, and metal alloys. For example, shrinking the crystalline patterns of steel makes the alloy stronger, and this makes the anticrystal a better starting point for describing it.
Source: University of Pennsylvania
Posted: July 8, 2014 02:02PM
Graphene is a wonder material for many reasons, including its fantastic electrical properties and great strength. It is also special for being a high quality crystal, which can have implications for quantum mechanics. Researchers at Columbia University have recently discovered a means to tune a quantum mechanical phenomenon in bilayer graphene, which could enable it to be used in quantum computers.
The fractional quantum Hall effect involves many electrons being made to act like a single system when confined to a thin sheet and exposed to a large magnetic field. As graphene is an atom-thick sheet of carbon, it is a perfect fit for studying the effect, and it has been. This new research looks to bilayer graphene, which has some differing behaviors from single-layer graphene, such as developing a bandgap when exposed to a strong magnetic field, disrupting the electrodes ability to tune the charge density. It took some time, but the Columbia researchers eventually found a new design for the graphene system that allowed them to isolate the electrodes from the needed magnetic fields.
Now with the ability to control the charge density on the separate graphene sheets, the researchers can create the fractional quantum Hall effect in bilayer graphene, which could allow for non-abelian states to be created. These states could be used for quantum computation, but not before the researchers better understand what is happening to the electrons, as the system is so complex they are not entirely sure what is occurring.
Posted: July 8, 2014 06:59AM
Since its discovery, researchers have been working to find a way to make use of graphene in our electronics. This has been difficult though, as graphene is an electrical conductor and not a semiconductor, like silicon. Researchers at the University of Wisconsin, Milwaukee however have found that graphene nano-ribbons can become semiconductors, just by making them the right width.
Graphene is an atom-thick sheet of carbon and often worked with as a sheet, but other geometries can have special properties. As it turns out, nano-ribbons of graphene, which are typically conductors like larger sheets, can become semiconductors if they are three nanometers wide, or less. At such a small width, the electrons on one edge are able to interact with the atoms on the other, resulting in the sought-after semiconductor behavior.
Cutting the nano-ribbons that narrow is not easy though, especially as the edges have to possess the proper alignment. The researchers accomplished this with iron nanoparticles that catalyze a reaction between carbon and hydrogen atoms. Now the researchers are investigating other ways to change the properties of the nano-ribbons, by adding other atoms, such as oxygen to the edges, potentially making them act as a metal.
Posted: July 7, 2014 02:21PM
An important and useful property for many optical systems is linearity. Essentially it is why light passing through glass is the same when it exits as when it enters the material. Nonlinear materials however can change light waves, and researchers at the University of Texas at Austin have recently developed a nonlinear meta-mirror that doubles the frequency of the light it reflects.
Nonlinear materials are rare in Nature and are generally not too efficient, requiring high intensities and great distances for the light to propagate through. Metamaterials however are completely unnatural as their optical and electrical properties have been tuned to something that would normally be impossible. Using metamaterials though, the researchers were able to build a device just 400 nanometers thick that would bump the wavelength of light from 8 micrometers up to 4 micrometers; doubling the frequency. Unlike natural nonlinear materials, this device is able to convert light with intensities near that of laser pointers.
The creation of such an efficient and small nonlinear optical system could have many impacts on future optical systems, such as miniaturizing some laser systems. These systems may not be ones in our electronics though, but instead those used in advanced sensors for finding chemicals and explosives, as well as biomedical research and more.
Source: University of Texas at Austin