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Science & Technology News (536)

Magnetism in Iron-Based Superconductors Better Understood

Category: Science & Technology
Posted: August 27, 2014 06:22AM
Author: Guest_Jim_*

One day we may use electrical wires and cables capable of transmitting currents without resistance. The key to this future is understanding superconductivity, the phenomenon that enables it. Researchers at Oak Ridge National Laboratory and Vanderbilt University have recently made an interesting discovery concerning iron-based superconductors that challenges some long held beliefs.

Superconductivity arises in certain materials when they are brought down below some critical temperature. For the earliest superconductors, this temperature was just above absolute zero, but since then we have discovered high-temperature superconductors that have critical temperatures significantly higher, though still far from room temperature. Some of these superconductors are iron-based materials, which was unexpected initially as these materials also have magnetic properties. Large-range magnetism is known to suppress superconductivity, but now it has been discovered that local magnetic moments do not disrupt it In fact these isolated areas of magnetism within the material may assist superconductivity, as they are at their maximum when superconductivity is. The researchers also discovered that the number of electrons in the moments was the same for different kinds of iron-based superconductors, though their distributions differed.

Beyond the potential for understanding superconductivity better, this research could also have an impact on other technological materials and devices. To do the study, the researchers had to develop a way to measure the local moments, which had not been done before as previous research always looked at the bulk average.

Source: Oak Ridge National Laboratory



Using Sound Waves to Sort Cells

Category: Science & Technology
Posted: August 26, 2014 03:40PM
Author: Guest_Jim_*

Just about every cancer can be a big problem, and all are dangerous when they spread, which makes it vitally important to know if it is. Catching cancer cells in a patient's blood is very difficult though, because of how few cells there can be, and that many methods for sorting cells are complicated or can damage the cells. Researchers at MIT, Pennsylvania State University and Carnegie Mellon University however, have developed a device for sorting cells with great accuracy, and relative ease.

Instead of relying on chemical tags or strong mechanical forces, this method utilizes sound waves to gently guide cells. By using two acoustic transducers on either side of a microchannel, a standing wave can be made with a pressure node parallel to the flow. This much has been accomplished before and did demonstrate that cells of different size, compressibility, and other properties, would be pushed around differently. What has been added now is a tilt, putting the pressure node at an angle, relative to the flow. This causes the cells to pass through multiple nodes, and be slightly pushed to one side, and cells of different physical properties are still affected differently.

The researchers have already tested it with plastic beads 9.9 and 7.3 microns in size, demonstrating 97% accuracy, and were able to recover 71% of cancer cells in a sample that included those and white blood cells. They also created a computer model that can predict how cells will be affected based on its properties and the angle of the sound waves, which opens up the possibility of device customization.

 

 

Source: MIT



Seeing Color with a Photodetector

Category: Science & Technology
Posted: August 26, 2014 11:05AM
Author: Guest_Jim_*

Color blindness affects only about nine percent of people, but just about every digital camera is unable to discern color with just its detector. Color images are the result of filters external to the photodetector that separate incoming light to the red, green, and blue we are familiar with. Researchers at Rice University however, have developed a photodetector with color sensitivity, while studying cephalopods.

How are cephalopods like squids related? These species have very odd skin, which the Office of Naval Research wants to be studied. Cephalopods are color blind, but it is suspected that they can still detect color with their skin, and it was from this hypothesis that the Rice researchers developed the new photodetector. On top of the typical silicon photodetector, the researchers put a layer of aluminum that was etched into, using a process commonly used in CMOS process. The thickness of an oxide layer was also manipulated to create a plasmonic grate on the detector's surface. With such control, grating could be tuned to only allow certain frequencies of light through, and to focus that light onto the detector.

Unlike the filters traditionally used in digital cameras, this plasmonic grating can be built directly onto silicon photodetectors using standard CMOS techniques. Beyond the advantages of being part of the chip, this grating is also smaller and simpler and the filters, all while mimicking how organisms detect colors.

Source: Rice University



To Teach Future Robots, Use Robo Brain

Category: Science & Technology
Posted: August 26, 2014 07:22AM
Author: Guest_Jim_*

As my mother and father will both exclaim at times, computers and machines can be quite dumb. For now, that is just annoying, but if we ever start relying on robots to help in our homes, it could be a real problem. To head off potential problems, researchers at Cornell University have developed Robo Brain and set it the task of processing content on the Internet, in order to learn and teach other machines.

Though currently our computers and other devices are able to find us the answers to almost any of our questions, it is not in a form that the computers can understand. This is what Robo Brain addresses by associating text with images and videos, to recognize objects and learn human language and behavior. It stores this information with a Markov model, which consists of nodes representing objects, actions, or parts of an image, and edges connecting them. When another robot searches for knowledge, it starts with its own chain of nodes, and will look for a similar one Robo Brain built. As there may be differences between what Robo Brain and the robot built, probabilities have been assigned to the nodes of Robo Brain that represent allowed variance.

As Robo Brain may get some things wrong, or just need some help, you can visit its website to provide corrections and additional information: RoboBrain.me.

Source: Cornell University



Digital Media May be Degrading Children's Social Skills

Category: Science & Technology
Posted: August 25, 2014 02:13PM
Author: Guest_Jim_*

Okay, this is probably something that will not surprise many people. A recent study from the University of California, Los Angeles has shown that the use of digital media can impair a child's social skills. More specifically, by spending time looking at a screen instead of interacting with someone face-to-face, the children are not learning how to read emotional cues.

For the study, the researchers used two groups of sixth graders. Both groups were given a test at the beginning of the study, to determine their ability to recognize emotions that was repeated at the end. In the interim, one group of 51 students went on a five day trip to a nature and science camp that does not allow the use of electronics. Before going to camp, the group made an average of 14.02 errors on the test and at the end of the study though that number dropped to 9.41. The 54 students who did not go to the camp at that time saw little or no change in the number of errors made. The students reported that they spend, on average, 4.5 hours each school day with digital media, in one form or another.

While the study does rather strongly indicate one negative with digital media, at least it also shows it can be addressed, to a point. Make sure the kids get some face-to-face time, away from devices and they should be in better shape.

Source: University of California, Los Angeles



New Tool for Checking Software Security

Category: Science & Technology
Posted: August 25, 2014 08:53AM
Author: Guest_Jim_*

Some say that information is the most valuable commodity in the world currently, so naturally it has to be protected. This can be challenging though, especially with complex software systems that handle information of multiple safety levels. Researchers at Karlsruhe Institute of Technology have recently created a new tool that checks for possible security leaks, and help keep data safe.

The tool is called JOANA and works by checking the data channels a piece of software will run data through. It will identify channels that are publicly visible and those that are secured, and find where they may cross. As you can guess, secure data is most likely to be exposed at these crosses of secret and public information. There the data can get out by explicit leaks, by implicit leaks that expose patterns in the encryption, and by probabilistic leaks that could allow data to be reconstructed. Even though that last type of leak is particularly hard to identify, JOANA is able to catch it and even has a low false alarm for it.

As it stands now, JOANA is the only software analysis tool for finding all three kinds of security gaps without having a high false alarm rate. Low false alarm rates are very important, as we do not want resources to be wasted hunting a nonexistent issue or for real issues to be erroneously dismissed.

Source: EurekAlert!



Do we Prefer Robotic Authority?

Category: Science & Technology
Posted: August 25, 2014 05:46AM
Author: Guest_Jim_*

As technology improves, it is understandable that it has a growing presence in completing tedious tasks. According to a variety of science fiction stories though, many of us have been taught that it is not necessarily a good thing to let robots have too great a role in the work. Researchers at MIT decided to put that to the test, and initially hypothesized that a sweet-spot of shared human and robot control would exist.

The study used groups consisting of two humans and one robot that could have one of three configurations. One has the human workers allocating all of the work, another has the robot allocate all of the work, and the last one has one human allocate their own tasks, while the robot sets tasks for the other. As expected, the configuration which had the robot allocating all of the tasks was the most efficient, but it also had the most satisfied human workers. This surprised the researchers as the workers reported feeling that the robot "better understood them" and "improved the efficiency of the team."

Though a physical robot was involved in the study, this result does not suggest that they should be involved in every task. What it does show is that giving control of scheduling, delegating, and coordinating tasks to algorithms instead of people may be a better idea than anticipated.

 

 

Source: MIT



Quantum Rotation Observed in Helium Nanodroplets

Category: Science & Technology
Posted: August 22, 2014 02:00PM
Author: Guest_Jim_*

Take a material to an extreme, and you can expect to see some weird things happen. One example is superconductivity, and another is superfluidity, in which a liquid will flow with zero viscosity. Helium, when cooled enough, can become a superfluid, and researchers at Berkeley Lab and the SLAC National Accelerator Laboratory have recently answered a question about how nanodroplets of helium behave.

Superfluidity is the result of the atoms in the liquid coupling together to act as though they are a single particle. This removal of viscosity can lead to some interest behaviors, such as the liquid climbing up walls. For superfluid helium, we have known for decades that rotating it will cause quantum vortices to form, regularly spaced throughout the liquid. Whether this behavior also occurs in an isolated nanoscale droplet has been an open question for some time now, and if they are present, that would mean the entire droplet acts like a single quantum object, instead of a mixture of particles.

To create the nanodroplets, helium is passed through a nozzle that has been cooled to below 10 K, and shot into a vacuum chamber at almost 200 m/s. To image the droplets before they had a chance to vanish, the researchers had to use SLAC's Linac Coherent Light Source to create very short pulses of high energy X-rays. Xenon atoms were also added to the helium, to make the vortices visible, and indeed they were. In fact the vortices behaved like those in larger samples of superfluid helium, though the nanodroplets were also clocked spinning 100,000 times faster than any previous rotating superfluid helium sample. Despite that high speed though, the droplets did not deform, like normal liquid drops would. Potentially, studying these drops could lead to a better understanding of superfluidity, thanks to how isolated the property is.

Source: Berkeley Lab



Improved Semi-Artificial Leaf Developed

Category: Science & Technology
Posted: August 22, 2014 10:16AM
Author: Guest_Jim_*

With how much energy comes to Earth as Sunlight, it is not surprising that we are working on ways to capture and harness it for our own uses. While some means for doing this do exist, we are still searching for better methods, such replicating Nature's photosynthesis, which is a rather efficient process. Researchers at Ruhr-University Bochum have recently succeeded in creating a semi-artificial leaf that could help bring about cheap and flexible solar cells in the future.

Semi-artificial leafs that use photosystem 1 (PS1) for absorbing light, instead of a semiconductor, have been worked on before, but PS1 has a special complicating factor. It possesses both hydrophilic and hydrophobic domains, which makes it difficult to keep immobile on electrodes. To solve the problem, the researchers created a hydrogel matric, which can have its own hydrophobic/hydrophilic properties shifted by adjusting pH levels.

The resulting semi-artificial leaf outperformed other semi-artificial bio-photoelectrodes, but also bested Nature with an electron transfer rate ten times greater. Though modern, semiconductor photovoltaics are still superior, that may change in the future, and for now the bio-photovoltaics may find use in micro-scale medical devices.

Source: EurekAlert!



Droughts in Western US Affecting Geography

Category: Science & Technology
Posted: August 22, 2014 05:59AM
Author: Guest_Jim_*

The droughts that have been hitting the western US in recent years are having more of an effect than probably most people would expect. Beyond the water restrictions and some dying plant life, geological data suggests the droughts have caused the entire west coast to wise a little, according to researchers at the University of California, San Diego.

Across the country there are networks of highly precise GPS stations, and those along the west coast have seen an apparent uplift in recent years. More specifically the uplift has coincided with the droughts the states in the area have been suffering. Analysis of the data indicates that some of California's mountains have risen 15 mm (over half an inch) with an average of 4 mm across the west.

Crunching the numbers reveals that approximately 240 gigatons of water, or 62 trillion gallons, would have to be missing to explain the vertical shift. This opens up a new use for GPS networks as a potential means to measure water stocks across the world.

Source: University of California, San Diego



Major Android Security Flaw may be Shared in iOS, Windows

Category: Science & Technology
Posted: August 21, 2014 12:57PM
Author: Guest_Jim_*

As we use our mobile devices more and more, the importance of securing them becomes greater and greater. Researchers at the University of California, Riverside have recently discovered a security flaw in the Android OS with almost a perfect success rate, and almost all popular operating systems may share the vulnerability.

The vulnerability has to do with the shared-memory side channel, which contains shared memory statistics about processes and can be accessed without permissions. From this information, it is possible to infer what an app is doing, such as logging in or receiving information for a purchase. On its own, this vulnerability is not serious, but the researchers found it could be used to time an attack that exploits a feature of many modern GUIs, which is why more than just Android may be at risk. The feature is to allow the screen to be preempted, such as to show an alarm. In this case though, what comes up is a false version of the expected window. By timing the attack with the shared memory data, the user will fail to notice the switch.

The researchers tested the attack on seven apps and here are their success rates (higher is worse): Gmail at 92%, H&R Block at 92%, Newegg at 86%, WebMD at 85%, CHASE Bank at 83%, Hotels.com at 83%, and Amazon at 48% success rate. The reason Amazon has the lower success rate is because it is harder to infer the state of the app, as it can transition between almost any activity.

 

 

Source: University of California, Riverside



Improving AFMs with Lasers

Category: Science & Technology
Posted: August 21, 2014 10:42AM
Author: Guest_Jim_*

Lasers are a cool technology, but as science fiction and some science fact tells us, the beams themselves are not cool and can be used to heat and melt objects. As some other science facts also tell us though, lasers can be used to cool objects by exploiting or great control over the properties of the beam. Researchers at the Australian National University have recently used this control to cool the tip of an atomic force microscope, making it much more accurate.

Atomic force microscopes (AFMs) are among the more advanced measurement devices we have and operate by moving a cantilever with a very sharp tip over a sample. At its point, the tip can be just nanometers wide and is very sensitive to forces, such as a surface pushing against it, but also forces between molecules. It is so sensitive though that heat will cause vibrations that introduce noise to the measurements. The Australian researchers decided to tackle that noise by aiming a laser at the probe. By precisely tuning the laser, the vibrations of the probe can be cancelled out, cooling the probe to -265 ºC. This increases the sensitivity enough to detect the weight a large virus.

As the laser beam's effect overwhelms the probe, the AFM cannot be run when the laser is turned on, restricting the researchers to make measurements in millisecond long heating and cooling cycles. With additional study and data processing though, we may one day see the same sensitivity achieved without a cooling laser, thanks to our understanding of the cooling effect.

Source: Australian National University



Using Saltwater for Power

Category: Science & Technology
Posted: August 21, 2014 06:24AM
Author: Guest_Jim_*

In many cases, electricity is generated by driving turbines with one fluid or another, such as steam or water. What can really set power plants apart is what puts the energy into the fluid that the turbines extract. One new method may use salt for that purpose, and researchers at MIT have found that such a system is not as simple as believed.

If you have two fluids with different solute concentrations separated by a semi-permeable membrane, such as having saltwater on one side and fresh water on the other, the fluids will move to try to equalize the concentrations on both sides of the membrane. The motion of the fluids is called osmosis, and pressure retarded osmosis (PRO) is a process some have been investigating for producing electricity. The idea would be to put pressurized salt water on one side of a membrane and fresh water on the other, and use the movement of the fresh water through the membrane to turn a turbine. What the MIT researchers have discovered is that the efficiency of a PRO system is more complicated than previously thought. According to their new model, the optimal membrane size is not the maximum membrane size, as a membrane half the area could produce 95% of the maximum output power.

Potentially PRO systems could be used to power desalination plants and water treatment plants, by putting saltwater or brine on one side of the membrane, and fresh or waste water on the other. To completely power some treatment plants may require some of the largest membranes in the world, but new configurations are being developed to fit the millions of square meters in relatively small packages.

Source: MIT



Using Earth's Magnetic Field to Characterize Materials

Category: Science & Technology
Posted: August 20, 2014 02:06PM
Author: Guest_Jim_*

Though we may not think about it much, we are all aware of Earth's magnetic field. The most obvious use of it is to orient compasses, but it has other uses too, as it is used for probing in geology and archaeology. Thanks to researchers at Berkeley Lab, it may soon also find use for analyzing chemical compositions of fluids, without removing them from their native environments.

Nuclear Magnetic Resonance (NMR) is a phenomenon that can be used to determine the materials in some sample, and possibly its most common use is medicine's MRI machines. It works by measuring how atoms behave when the angle of their spins are manipulated. Normally strong and uniform magnetic fields are used, but these are not always available. What is always available on Earth though is the planet's magnetic field. Attempts have been made before to use the Earth's magnetic field for NMR, but failed because the field is so weak and the equipment was not very sensitive. The Berkeley researchers have discovered that it appears to be possible now, by using highly sensitive optical magnetometers and by looking at how the spins of molecules relax and diffuse.

Potentially this technique could be used to characterize the contents of solids underground, such as in oil wells, and actually measure hydrocarbons and water within rock, as well as inspecting the curing process of polymers and cement. The researchers next want to increase the depth their method can reach inside of a material, possibly piercing a meter or more, instead of the inches possible with current technologies.

Source: Berkeley Lab



Improved Screening of Potential Organic Solar Cell Materials

Category: Science & Technology
Posted: August 20, 2014 09:39AM
Author: Guest_Jim_*

Many modern solar cells are made of materials like silicon and are expensive to produce. In the future though, new photovoltaics based on polymers could replace them by being cheaper and more resilient. Finding the right polymers is tricky though, but researchers at the University of Tsukuba and Nation Institute for Materials Science have found a way to speed up the search, as published by the American Institute of Physics.

Materials science can be an exhaustive field as the materials would be to be produced for testing, and only then could it be determined if the materials is of much use. By better understanding the behaviors of a material, it is easier to predict its properties and thereby speed up the process. This is what the Japanese researchers have accomplished for candidates for organic photovoltaics by combining two kinds of photo-induced spectroscopy. The two processes important for these materials are their charge formation and charge transport efficiencies, and it is believed that the charge formation efficiency is complicated and actually dependent on a thermal activation process. What the researchers discovered is that the temperature actually does not matter, as samples demonstrated the same efficiency at 80 K and 300 K.

This discovery indicates that the charge formation efficiency for organic photovoltaics is only quantum mechanical, which actually makes it simpler than expected. The result is that it should also be easier to quickly screen materials by this property, and in turn speed up searches for new organic photovoltaic materials.

Source: EurekAlert!



Bringing Fiber Optics to Computer Chips

Category: Science & Technology
Posted: August 20, 2014 05:57AM
Author: Guest_Jim_*

More and more, fiber optic cables are being installed for carrying information across networks and across the Internet, because they are great speed and capacity. Many would like to see fiber optics enter our computers as well, but shrinking the cables has been proving difficult. Researchers at the University of Alberta though, have managed to create nano-optical cables that could enter our computer chips.

Presently copper wires are used within computer chips as interconnects, because the metal does a decent job. Optical fibers could do better, but their diameter has been limited to the micrometer range, which is too large. By turning to metamaterials however, the Alberta researchers were able to go an order of magnitude smaller, without losing data, slowing the signal, or creating heat. As you can no doubt guess, bringing fiber optics into chips would also bring significantly greater speeds and efficiencies than what we see now.

Source: University of Alberta



Extending Coherence Time in Quantum Memory

Category: Science & Technology
Posted: August 19, 2014 02:09PM
Author: Guest_Jim_*

One of the biggest challenges with quantum computers is finding a way to store quantum information for extended periods of time. There are many different approaches being studied right now for preserving the information, and each has its own advantages and disadvantages. Now researchers at the Vienna University of Technology have combined two of these techniques and managed to extend the stability of the information.

One of the techniques being developed encodes the quantum information onto nitrogen atoms inside of diamonds, which protects them from external forces. Another technique encodes information onto photons trapped in a resonator. The researchers have combined these two concepts by using a microwave resonator to encode information onto multiple nitrogen atoms. This actually keeps the quantum information coherent for longer than it would normally by causing all of the nitrogen atoms to be coupled with the resonator. This mass coupling prevents the atoms from losing coherence, keeping the quantum information accessible for longer.

By opening the door to hybrid quantum technologies this way, it is hard to predict what new technologies may be created in the future. Of course quantum computers will see a benefit, but the potential of this research could be greater than longer memory storage.

Source: Vienna University of Technology



Finding How We Get Recommended Ads and More

Category: Science & Technology
Posted: August 19, 2014 11:40AM
Author: Guest_Jim_*

Unless you are exceptionally careful about what information is on the Internet, there is a good chance you have been presented with a recommendation based on your online activities. Of course we all know that services and websites collect information from emails, video views, and product views, but how exactly do they generate the recommendations? That is what researchers at Columbia University want to know, and so they have developed XRay to provide greater transparency on the Internet.

Approaching the problem of how our information is used is tricky, because much of the Internet operates like a black box. Without the ability to view the processes involved in generating the recommendations, XRay has to rely on black-box correlations between inputs and outputs. At first the researchers worked with theoretical results, which were encouraging, but only theoretical, so they soon started running experiments on Gmail, Amazon, and YouTube and refining the design. Eventually XRay achieved complete success with each experiment, matching theoretical predictions in complex cases, which suggests it can scale up well.

Though the current system has only been run on Gmail, Amazon, and YouTube, it should be service-agnostic, so any site that tracks you could be studied with XRay. Thus far it has revealed that it is possible to target sensitive topics and that there does appear to be abuse of the recommendation systems. You can see examples results at XRay's website: XRay: Transparency for the Web.

Source: Columbia University



Turning Car Batteries into Solar Cells

Category: Science & Technology
Posted: August 19, 2014 06:36AM
Author: Guest_Jim_*

Lead has quite a history as the soft metal once saw many uses, such as water pipes to additives for gasoline and paint, but is now restricted to just a few, due to its potential health hazards. That is also why we see so many recycling programs specifically for lead, to keep it from getting somewhere it should not, and to reduce the amount that needs to be acquired. Now researchers at MIT have devised another recycling program that could see lead repurposed for use in solar cells.

Perovskites are a family of compounds that share similar structures, and organolead halide perovskite is being looked at for use as solar cells. Some of these cells have already exceeded 19% efficiency, which makes them almost competitive with the silicon-based solar cells you can find today. The catch is the use of lead, especially as the solar cells would require more lead to be mined. The MIT researchers however have developed a process to take the lead from car batteries and use it for solar cells. As the lead compound would actually be a thin film, they predict that the lead of a single car battery would be enough to make enough solar panels to power 30 homes.

Along with providing another reason to recycle car batteries, this could also help bring the cost of solar cells down. The process is low temperature and requires fewer steps than conventional solar cells to produce, making it potentially easier to scale up cheaply.

 

 

Source: MIT



Combining Molecular Measurement Techniques on a Single Chip

Category: Science & Technology
Posted: August 18, 2014 01:57PM
Author: Guest_Jim_*

Many people likely associate the image of a table covered with beakers, flasks, burners, and at least one microscope with a chemistry laboratory, but that is likely to change in the future. Many groups around the world are working on creating lab-on-a-chip systems that will condense chemical testing equipment onto something the size of a computer chip. Researchers at the University of California, Santa Cruz have recently created a chip with the ability to identify single molecules by combining electrical and optical measurement techniques.

The chip utilizes a nanopore that acts as a smart gate, to control the flow of molecules into a channel. The nanopore also allows the researchers to make electrical measurements as the molecules crosses it. For DNA passing through the nanopore, the electrical measurements would actually be able to determine the genetic sequence of the DNA, by fluctuations of the current. Once in the channel, the molecule is also exposed to a beam of light, and changes to the light's intensity indicates the size and optical properties of the molecule, as well as the flow speed through the channel.

When the researchers tested their chip with a mixture of influenza viruses and nanobeads of similar diameter, tagged with fluorescent labels, they found that they were able to distinguish between the two particle types using their electrical and flow properties with perfect accuracy. They were even able to count the number of virus particles, which would be very useful for analyzing samples.

Source: University of California, Santa Cruz



Finding the Impact of Impurities on Graphene

Category: Science & Technology
Posted: August 18, 2014 08:40AM
Author: Guest_Jim_*

Some people may not always think about it, but impurities are important to our way of life. The changes impurities can cause in many materials has enabled and improved many technologies we have come to rely on. Now researchers at Rice and Osaka universities have found how much impurities can disrupt graphene, a material many hope will be central to future technologies.

Graphene is an atom-thick sheet of carbon with special electrical properties, including great electron mobility. Of course for those properties to be useful in future technologies, they must persist, but the researchers have found that they can be greatly affected by impurities from the environment. The researchers grew a sheet of graphene and transferred it to an indium phosphide substrate for this research. When femtosecond laser pulses struck the graphene, the indium phosphide reacted by emitting terahertz radiation that passed through the graphene. Using a spectrometer, the researchers were able to detect imperfections as small as an oxygen molecule, as they affect the electric field of the graphene, and disrupted the terahertz radiation.

Of course the knowledge of how much graphene can be affected by imperfections is going to impact the development of technologies that may use it. One potential technology may be to actually adapt this experiment's design as a highly sensitive gas sensor.

Source: Rice University



Looking at the Edge of Graphene

Category: Science & Technology
Posted: August 18, 2014 05:30AM
Author: Guest_Jim_*

Graphene is an amazing material with its special mechanical, electrical, and optical properties, making it of key interest to many. The hope is to one day use it in a variety of devices such as advanced sensors and higher speed and efficiency electronics. Now researchers at the National Physical Laboratory have discovered that the edge of graphene has some interesting properties that could influence some future applications.

One of the main reasons graphene is studied so much is that electrons can move along it at great speed and with little resistance. Such electron conduction would be very useful for many devices, but the NPL researchers have discovered that the edge of graphene conducts differently. While the bulk of the plane conducts electrons, the edges instead conduct the positively charged holes left behind by excited electrons. Effectively this makes the interior of a graphene sheet n-doped with the edge p-doped, and while both can conduct electricity, the differences are important for designing devices.

With side-gates the researchers were able to tune the conduction of the edges without affecting the center. The researchers also discovered that the differences in conduction were most pronounced after the graphene had been cleaned, but faded over time, suggesting it is the result of defects that were filled by airborne molecules.

Source: National Physical Laboratory



Coming Closer to Solving the Proton Spin Crisis

Category: Science & Technology
Posted: August 15, 2014 02:00PM
Author: Guest_Jim_*

Normally one would expect that an object can be described as the sum of its parts, depending on what specific property you are describing. For protons, many believed that their spin was the combination of the spins of the particles that make it up, but in the 1980s experiments showed this was not the case. Since then researchers have been working to solve the proton spin crisis, and those at MIT have some new evidence.

According to the standard model, protons are made of two up quarks and one down quark, which do add up to the positive charge of the larger particle. Adding the spins of the quarks up does not result in the spin of the proton though, so researchers have been searching for where the additional spin must come from. One theory is that the bonds between the quarks occasionally break, and this allows pairs of quarks and antiquarks to briefly appear and annihilate, contributing to the proton's spin while they exist. To test this, the researchers collided a number of protons, which produced some W bosons. These bosons would have the spin of any antiquarks that were present when the proton collided, thereby allowing the researchers to determine how great an influence the quark-antiquark pairs have on proton spin.

As it turns out, the spin of the antiquarks is only marginal and not enough to solve the crisis. All is not lost though, in a larger sense, as the information collected gives a much better understanding of how up-flavored antiquarks behave and come to exist. This will aid future studies into the crisis as well.

Source: MIT



Analysis of Interstellar Dust Begins

Category: Science & Technology
Posted: August 15, 2014 09:20AM
Author: Guest_Jim_*

Several years ago, NASA's Stardust mission took to space to collect particles from a comet's tail and possibly interstellar dust, before sending them back to Earth. There have already been many studies published about the particles from the comet's tail, but we are only starting to see analyses done of the much more special interstellar dust grains. Among those institutions studying the dust is Berkeley Lab.

While on its way to the comet, Wild 2 the Stardust spacecraft exposed its collector to space, with the hope of catching some dust particles that may be from outside the Solar System. As you can guess, such particles would be very rare and would provide unique insight into our little corner of the galaxy. To that end, the researchers have examined seven grains that may be interstellar dust using non-destructive techniques. Three of these were found in the aerogel while the other four left pits and residue on the aluminum foil. The two larger grains found in the aerogel surprised the researchers as they had a fluffy composition, like a snowflake, which is counter to the expectation of interstellar particles being dense. They also contained the mineral olivine, which would suggest they came from the disks or outflows of other stars. Three of the particles found in the foil contained sulfur compounds, which are not believed to exist in interstellar dust. Further study will be needed to explain the presence of these compounds.

While the current analyses of these grains will prove very informative, the most important examinations are still in the future. Those are to determine if these grains are indeed from outside the Solar System, but as the experiments would destroy the precious grains, tests are being done on analogs first.

Source: Berkeley Lab



Thousand-Robot Swarm Created

Category: Science & Technology
Posted: August 15, 2014 06:15AM
Author: Guest_Jim_*

One of the many interesting phenomena in Nature is swarming, whereby individual organisms, like ants, cells, and fish, will act together to achieve something no single individual could. This behavior is something many have been trying to replicate with robots, as a means to improve their effectiveness and to test their AI. Researchers at Harvard University have recently created the first thousand-robot swarm and gotten it to form human-specified shapes.

The swarm consists of 1024 robots called Kilobots, for obvious reasons, and each of these devices are just a few centimeters wide and stand on three thin, rigid legs. Two vibrating motors are used to get the robots sliding over a surface while infrared light is used for communication. This simple design kept the robots cheap, but also increased the chance of errors, but fortunately the algorithm driving them is smart enough to detect and actually correct the errors. In fact the algorithm has been proven to allow the robots to complete the task given to it. To get the robots started, they are given the image to recreate and four are then used to designate the origin of the image. Next the arbitrary mass of Kilobots starts moving one by one along the edge, until they reach the next point to fill in the image.

This is the first time a swarm consisting of a thousand robots has been tested and is an important milestone for distributed robotics. In the future we may see robots swarms being used for cleanup, rescue efforts, and even as chauffeurs as self-driving cars would be an example of distributed robotics.

 

 

Source: Harvard University



Silicene's Stability Shown

Category: Science & Technology
Posted: August 14, 2014 03:20PM
Author: Guest_Jim_*

Carbon and silicon share many properties because they are in the same family of elements. This also means that the structures one element can form, the other likely can as well. Silicene is the silicon equivalent to graphene and now an international team of researchers has successfully demonstrated its stability in open air, as reported by the Institute of Physics.

Like graphene, silicene is an atom-thick sheet of silicon atoms in a hexagonal pattern, but it is tricky to make and can be destroyed by oxygen. To grow silicene, a silicon wafer has to be heated in a vacuum chamber, so the silicon atoms can come off of the wafer and deposit on a substrate, typically silver. If too many layers of silicene stack up, the material will degrade back into silicon, which is a more stable structure. Also if it is exposed to oxygen, the formation of the layers can be destroyed. The researchers however successfully built up 43 layers of silicene and exposed it to open air for a full day, before it degraded. It appears the oxygen in the air did react with the top layer to form a thin oxidation layer, which actually protected the stack.

The hope is that one day silicene and other 2D forms of silicon will be used in electronics. In particular the material may be used to create silicene-based MOSFETs.

Source: Institute of Physics



Tractor Beam Created in Water

Category: Science & Technology
Posted: August 14, 2014 09:24AM
Author: Guest_Jim_*

A classic technology of science fiction is the tractor beam, which by some means is able to hold and move a remote object without directly touching it. Such functionality has been reproduced optically, but that only works on relatively small objects. Now researchers at the Australian National University have discovered that it is possible to create a tractor beam using water waves quite easily.

Normally one would expect that water waves would push objects away, or leave them where they are. At certain amplitudes and frequencies though, the researchers found that the ping pong ball they were testing with would move against the waves. According to advanced particle tracking tools, the waves were generating flow patterns on the surface of the water that would move the ball around. Different patterns would result in different movements.

Presently, there is no mathematical theory to explain these observations, but we can already envision applications. This could be used to manipulating floating objects and even trap and confine oil spills to certain regions.

 

 

Source: Australian National University



Harnessing Sweat for Power

Category: Science & Technology
Posted: August 14, 2014 06:02AM
Author: Guest_Jim_*

Though some may find it disgusting, sweat is a useful material as performs a necessary for regulating body temperature. It also contains compounds that can provide information about a person thanks to some new research, as reported by the American Chemical Society. The researchers went farther than just creating a sensor though by building a biofuel cell powered by sweat.

When people exercise, the body needs energy to fuel its muscles, and for particularly strenuous activities it activates glycolysis. This process produces the needed energy as well as the compound lactate, and by measuring the amount of lactate, a doctor can determine the person's fitness. Traditionally making these measurements required taking blood samples, but the researchers discovered a way to actually measure it in sweat using electrochemistry. The sensor, which has been built into a temporary tattoo, actually pulls electrons off of the lactate molecule, creating a weak current, and measuring the current provides information on the amount of lactate. The researchers then took another step by adding a small biobattery to the device to current useable energy.

When tested on people of different fitness levels, the researchers found the least fit people produced the most lactate, which makes sense as their bodies are activating glycolysis earlier than more fit people. The maximum current was still only about 70 micro-Watts per cm2, or 4 micro-Watts, which is not much, but the researchers are confident they will be able to increase that with more work.

 

 

Source: American Chemical Society



Copper Foam Catalyst Developed

Category: Science & Technology
Posted: August 13, 2014 02:15PM
Author: Guest_Jim_*

If we lived in a perfect world, waste products could be easily converted into something useful, but thanks to the laws of chemistry and physics, that is not how things work. Reactions the produce energy also produce waste products that are more stable than the reactants, to changing them back is a difficult process. Researchers at Brown University though have found that copper foam could be used as a catalyst to convert carbon dioxide into more useful chemicals.

It has already been demonstrated that copper is the best choice of catalyst for reducing CO2 into more useful hydrocarbons, but it is not always that efficient at it. One way to improve it is to use a rough copper surface, as this creates more sites for the chemical reactions to occur. The Brown researchers investigated how well copper foam, which was only developed in the past few years, would perform, as its many pores and channels should also serve for reaction sites.

When tested the foam was much more efficient at converting CO2 into formic acid, which is used to feed microbes, than planar copper. The researchers also found that small amounts of propylene were also created, which has never been reported before with copper. It appears this was the result of characteristics of the foam structure, which could mean copper foam could be tuned to deliver certain hydrocarbons in greater amounts.

Source: Brown University



Optical Angular Selectivity Achieved

Category: Science & Technology
Posted: August 13, 2014 10:12AM
Author: Guest_Jim_*

Some of you may have noticed that looking at water with polarized sunglasses can cause the water to change appearance, depending on the angle you look at it. The reason for this is that at a certain angle, the Brewster angle, the light reflecting off of the surface is polarized. Researchers at MIT have recently developed a way to manipulate the Brewster angle to create a material that will reflect light at every angle, but one.

Normally when light comes to the boundary of two materials with different refractive indices, it will be mostly reflected, but at the Brewster angle, only some of the light is reflected, with the rest passing through. What the MIT researchers have done is created a photonic crystal that has a very narrow band of angles that will allow light to pass through it. Basically it is a mirror at all but a single angle, its Brewster angle, when it becomes transparent. To create this crystal, the researchers actually stacked one hundred photonic crystals with alternating refractive indices.

There are a number of potential uses for this angular selectivity, including privacy filters, light detectors, telescopes, and even solar power. As sunlight strikes a solar panel, it will heat up and radiate out some of the energy, but with an angular selective layer on top, the sunlight could be let through while the radiated energy is reflected back to the absorber.

Source: MIT



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