Science & Technology News (347)
Posted: April 18, 2014 02:19PM
Computer technology has changed rapidly over the past decades, and while current hardware may not much resemble its predecessors, it is still using some of the same systems. Those systems may still work, but they were designed for a very different situation, and now what enabled performance in the past may be hindering it now. As reported by the National Science Foundation, the paging system for mapping data in memory is one such legacy system, and changing it could have large impacts on large tech companies.
Paging algorithms were created to allow programs to be addressed in memory in a noncontiguous way. When you have a limited amount of memory this is very valuable, but as RAM has increased in size, it has become less important. Its ability to address data and processes now adds complexity to computers that is not always necessary, and that takes up some resources. For a personal computer, those lost resources may not be enough to be noticed, but for large companies running server banks, the nanoseconds lost could be worth millions of dollars.
The researchers have already developed a new system that is more selective, so it will only use paging when needed. This could potentially return not only those nanoseconds but could also allow for increased performance for virtual memory and GPUs.
Source: National Science Foundation
Posted: April 18, 2014 07:37AM
For untold eons, humanity has wondered if we are alone in the Universe. Though we have not yet found alien life, we have been looking for places it may reside. Recently researchers from multiple institutions have found the first Earth-sized planet within the habitable zone of its sun.
The habitable zone covers the range of orbits about a star where the temperature is not too cold to freeze water into ice, or boil it off. Naturally our interest in the habitable zones come from the reliance life on Earth has on liquid water and an assumption that other life in the Universe also requires it. The host star for this planet is Kepler-186, the planet is named Kepler-186f, and both are located 500 light years away in the constellation Cygnus. The star is actually an M1-type dwarf star, which makes it cooler than the Sun, and is over five hundred thousand times dimmer than the stars we can see with the naked eye. It also has other planets in its orbit, these are much closer to it though and therefore much hotter.
Finding the planet required putting multiple observatories to work, including the Kepler spacecraft and the two terrestrial telescopes, Gemini North and Keck II. Kepler detected the planet by measuring the small dip in brightness it causes as it transits in front of the star. As many objects could cause such dimming, the other telescopes were employed to closely examine the system within 400 million miles of the star, to ensure that only a planet in the habitable zone could be the cause. Combining the data with calculations gives the researchers 99.98% confidence in this conclusion.
Source: Gemini Observatory
Posted: April 17, 2014 02:55PM
Bulk metallic glasses are curious materials that can possess great strength while being very durable and can take on shapes typical metals cannot. Finding metallic glasses is a long process though as it involves creating and testing each one. Researchers at Yale University however have combined two techniques that can dramatically speed up this process from one material a day to almost 3000.
Bulk metallic glasses are special alloys, often made of three or more elements that have been heated and cooled in such a way as to cause their molecular structures to be disordered. This results in the material having special properties that can be very valuable. Only being able to find one a day though limits their potential though, but with parallel blow forming and combinatorial sputtering, that should change. Parallel blow forming is a process that creates bubbles in alloys, which can be used to measure pliability while combinatorial sputtering though is a way to produce thousands of alloys all at once. Together the researchers are able test thousands of alloys at once, immensely speeding up the process.
With traditional methods, it is estimated that testing all 20 million possible bulk metallic glasses would take 4000 years, but with this method the work could be completed in just four. Those metallic glasses already discovered are used in sporting goods like watches and golf clubs, but metallic glasses could have applications in biomedical technologies, such as implants, as well as consumer electronics.
Source: Yale University
Posted: April 17, 2014 06:43AM
An immense amount of energy pours onto the surface of the Earth from the Sun every day, so naturally we are trying to find ways to harness it. In the future it may be that our windows will be converting some of that energy into electricity. Researchers at Los Alamos National Laboratory have recently developed a special quantum dot that addresses one issue preventing those windows from becoming a reality.
Quantum dots are nanoscale semiconductor crystals that can be tuned to have specific optical properties. By adding them to glass a luminescent solar concentrator (LSC) can be created, as the dots will absorb some of the light that passes through the window and then re-emit it as a different color. This light will then travel through the glass until it reaches a solar panel at the edge, which converts it into electricity. One of the issues with such an LSC is that the quantum dots will absorb some of the light they emit, which causes some energy to be lost. The LANL researchers addressed this by creating quantum dots with separated components for absorption and emission. This allows it to emit a color of light that the dots will not absorb.
When tested the LSC the researchers built demonstrated almost no energy loss due to re-absorption. It also achieved a good harvesting efficiency of 10% of photons that could be absorbed, without compromising the sample's transparency.
Source: Los Alamos National Laboratory
Posted: April 16, 2014 02:08PM
Right now there is considerably more photons passing through us than we can see, because the receptors in our eyes only respond to a small portion of the electromagnetic spectrum. Semiconductors likewise only react to light of certain frequencies, which can be frustrating when you want to detect more light than is in that range. Researchers at Georgia State University have found a way to tune those frequencies though, which could open up many possibilities.
Electrons, like many objects, need so much energy to start moving. In a conductor the required energy is very, very low while in an insulator it is very high. Semiconductors are somewhere in the middle, so when a photon strikes a semiconductor, it has to impart enough energy to get an electron moving to create a detectible current. This means detecting photons of lower frequencies and energy typically requires special semiconductors, but the Georgia researchers have found a way around this. Instead of changing the semiconductor, the researchers have added another light source. This extra light primes the semiconductor with enough energy so that even a lower energy photon can kick an electron, and create a current.
The device the researchers built was able to detect photons with wavelengths as great as 55 micrometers, which is significantly longer than the 4 micrometers the device would normally detect. Potentially this technique could be used for advanced sensors that can detect certain gases as well as building solar panels that absorb more of the spectrum.
Source: Georgia State University
Posted: April 16, 2014 09:11AM
In 2011 an earthquake and resulting tsunami struck Japan and so damaged the Fukushima Daiichi nuclear power plant that it lost the ability to cool the cores, which led to a meltdown. That event caused many around the world to consider the safety of current nuclear power plants, and how to make them safer in the future. Researchers at MIT have devised a new design for nuclear power plants that has the potential to remove earthquakes and tsunamis as a threat, by moving the plants far off-shore.
The idea of building a nuclear power plant off shore is not new as Russia is currently building a plant on a barge. The novel aspect of MIT's idea is to put the plants miles off shore, where the deepness of the ocean will protect the plant from earthquakes and tsunamis, just as how off shore oil and gas platforms are protected. The oceans offer more than just that protection though as nuclear power plants require large amounts of water to cool their reactors. On land this limits their locations to expensive shorefront areas. Also as the plants are mobile, they could be built and decommissioned at a central facility, like naval ships, which would improve standardization, and could reduce costs by using only steel, instead of both steel and concrete.
Currently this idea is just that, an idea, but is to be presented at the Small Modular Reactors Symposium being held this week. Of course offshore power plants need not be 'small' but could be built to rival the largest 1000 megawatt facilities you can find on land.
Posted: April 15, 2014 01:35PM
Silicon is a very useful material thanks to its semiconducting properties, but for some applications it has some issues. Or, more accurately, we have some issues getting it to work well for certain applications. One such application is using porous silicon to create hydrogen, but researchers at Penn State have found a solution.
Hydrogen is a very useful gas as it wants to react with a number of other elements and materials, and those reactions can release useable energy. The semiconducting properties of silicon make it well suited for generating hydrogen from water, but it will work best if the silicon is porous. Producing porous silicon is difficult and expensive though, as it requires etching away silicon, producing a lot of waste. The Penn researchers however have found a fairly quick and easy way to produce porous silicon from silicon tetrachloride, a relatively cheap silicon source. The key is to break the strong bonds between the silicon and chlorine atoms, which the researchers achieved with a sodium potassium alloy. This resulted in porous silicon with potassium chloride and sodium chloride in the pores, which could be removed with heat-treatment and water.
While porous silicon could have uses in sensors and other technologies, it can be used to produce hydrogen from water just with sunlight. When the light strikes the silicon, an electron can be excited, which causes the water to reduce and release hydrogen gas that can be captured and used as needed.
Source: Penn State
Posted: April 15, 2014 06:53AM
As our electronics become smaller and faster, they also become hotter, which is becoming a problem as that heat will limit performance and/or the lifespan of the device. Quite naturally researchers are working on ways to move the heat away from the circuitry more efficiently. Those at the Georgia Institute of Technology, University of Texas at Austin, and Raytheon Company have recently found a new thermal interface material (TIM) that is a bit different than you may expect.
Two of the factors that influence a TIM's efficiency are its conductance and its contact to the heat source. Many have been looking at better conductors, to move heat away faster, but the Georgia researchers decided to investigate materials that make better contact. In this case that material was a polymer. Typically polymers are insulators, but some can be made to conduct heat by adding aligned crystalline structures to them, giving the heat a path to follow. As the polymer in question, polythiophene, is a conjugated polymer, it has a high thermal stability, allowing it to survive at 200 ºC, unlike other polymers.
While the process used to make the material is not yet fully understood, the researchers are confident it can be scaled up for commercial use. It will be interesting to see how it compares to some conventional TIMs, as some of the best have only 1% contact with a device, compared to the 80% this polymer once achieved in other research. It was that research which led the Georgia researchers to consider polythiophene for this use.
Source: Georgia Institute of Technology
Posted: April 14, 2014 02:14PM
One of the fears shared by all users of mobile electronics is running out of power, and having to wait and wait for it to recharge. For now we have few options but to keep a charger handy, get a larger battery, and/or keep a second battery ready, if possible. Researchers at Tel Aviv University and the start-up StoreDot may have a new option for the future as they have created a battery that can fully charge in 30 seconds.
This new battery uses nanodots, which are bio-organic semiconductors made of peptides and have special electrochemical properties. By adding them to a battery they can increase both electrode capacity and electrolyte performance. Being organic and natural, they can also be produced very easily and cheaply. To demonstrate their capability, the researchers built a prototype battery for the Samsung Galaxy S4 smartphone, and fully charged it in half a minute at a recent Microsoft conference.
While the public may be especially interested in nanodots for their batteries, they can also be used to build sensors and displays with better color reproduction. Presently the prototype charger is about the size of that for a laptop, but the researchers are working to shrink it and bring it to market for late 2016.
Posted: April 14, 2014 05:58AM
Cellulose is the most abundant organic polymer on Earth thanks to its use in plant life. This makes it a wonderful resource to use, but finding useful applications can be difficult. Researchers at Oregon State University though have found a way to convert cellulose into a carbon material that is suitable as an electrode for supercapacitors, and other technologies.
Starting with cellulose, which can be in the form of filter paper, the researchers heat it and expose it to ammonia. This causes the cellulose to convert into an N-doped nanoporous carbon membrane. The resulting membrane is actually so porous that a single gram of the material can have a surface area of roughly 2000 square meters. Large surface area is invaluable in supercapacitors, as that is where the charge builds up and is stored.
After discovering this safe, easy, and cheap process of producing the membrane, the researchers were actually surprised no one had reported finding it before. Its discovery could affect a number of technologies, but just inexpensive supercapacitors could rock the automobile world by making electric and hybrid vehicles more efficient, faster charging, and perhaps safer as well.
Source: Oregon State University
Posted: April 11, 2014 06:08AM
Some day we want to see quantum computers running advanced algorithms no modern computer is capable of. Before that can happen though, we have to develop the technologies and understanding necessary to build quantum computers. Researchers at the California Institute of Technology have made an important discovery concerning both the required technologies and understanding.
Photons and electrons are two interesting particles with very different properties that make them ideal for certain, distinct applications. There is one quasi-particle that exists between these two, called a plasmon. Plasmons are oscillations of the surface electrons of a metal that reach the frequencies of light, and can be produced when a photon strikes a metal's surface. Because plasmons exist between electrons and photons, researchers have not been certain if its behavior can be described with quantum mechanics. To test this, the Caltech researchers found a way to replicate an optical experiment concerning quantum interference with plasmons. Normally one would fire two identical photons into a beam splitter, and quantum interference will cause the photons to exit on the same side. In this experiment two plasmons made by two identical photons pass through two waveguides to a directional coupler, which acts like a beam splitter.
The researchers found that, like with the photons and beam splitter, the two identical plasmons exited from the same side of the directional coupler. This demonstration of quantum behavior with plasmons could potentially lead to chip-based quantum devices and circuits, utilizing plasmons.
Posted: April 10, 2014 03:14PM
Year after year our electronics become more and more advanced, but this may not continue in the future as we approach the physical limits of the materials being used. For these reason alternative materials with better properties are being investigated, but there are multiple hurdles preventing their adoption. Researchers at Rice University and Nanyang Technological University have recently solved one of these issues with the semiconductor molybdenum diselenide.
Molybdenum diselenide is a semiconductor that can be made into atomic thick sheets. Graphene is possibly the most famous material 2D material, and definitely has some properties that we want in our electronics, but lacks some important ones. One such property is a band gap, which is necessary to build transistors from the material. Molybdenum diselenide has a band gap, but is difficult to produce, until now that is. The Rice researchers have discovered a stable and potentially scalable means to produce 2D sheets of the semiconductor using chemical vapor deposition.
Along with a band gap, molybdenum diselenide also has impressive electron mobility, which is a measure of how quickly electrons can move across it. Graphene is still orders of magnitude superior in this regard, which is why one day we may see both materials, with their complimentary properties, used to create advanced electronics.
Source: Rice University
Posted: April 10, 2014 06:46AM
Though perhaps not always recognized as such, steel is one of the most important materials to humanity, and the processes to manufacture it are equally vital. A major reason for this is the metals great strength and ductility, but sadly improving one of those properties tends to reduce the other. Researchers at Brown University and universities in China though have found a way around this with one kind of steel.
Twinning-induced plasticity (TWIP) steel is a kind of steel that forms special nanoscale structures called deformation twins, which increase its strength, or resistance to failure. Like other kinds of steel, hardening TWIP steel will cause it to lose ductility, or the ability to bend and deform without breaking. The Brown researchers however have found a way around this by deforming cylinders of TWIP steel a specific way. Typically one would bending, flattening, or hammering it on a forge, but instead the researchers twisted the steel, causing the outside of the cylinders to deform more than the inside. The result was a still ductile core with a doubly strong outside.
While the research was done using cylinders just centimeters long, there were no indications from the process that it cannot be applied to larger pieces of TWIP steel. Potentially we may see this strengthened steel used in drive shafts or axles in cars and trains, where cylindrical pieces of steel are already used.
Source: Brown University
Posted: April 9, 2014 01:34PM
Back before one could save contacts on phones, we had to input phone numbers to call someone. Thankfully we have not had to do the same with the Internet as a site's domain name is translated to its IP address for us. Researchers at Northwestern University have recently found that the servers that perform that translation can have a significant impact on how quickly our smartphones perform when web surfing.
Domain Name Servers (DNS) are a crucial part of the Internet as without them one would have to keep track of the IP addresses for every site they visit. Like any piece of hardware though, a DNS can become bogged down with requests. The Northwestern researchers were curious if the particular DNS service a smartphone uses could influence its performance exploring the Internet. To their surprise, it not only had an impact, but a large one as well. When tested, some services improved performance by up to 150%, compared to the DNS service one's carrier uses.
To help users find the best DNS service, the researchers created the Namehelp app, which is currently available in the Google Play Store. While it may find a better DNS for your location and the sites you visit, you may not be able to achieve any of that improved performance, unless you have rooted your phone, as carriers lock down what DNS you use on their networks (Wi-Fi would be different though).
Source: Northwestern University
Posted: April 9, 2014 07:20AM
A goal for many researchers is to develop biomedical micro-devices that can collect specific information easily and cheaply. While ultra-low-power chip-size electronics are becoming a reality, powering them is still a question, as the power source must be equally small. Researchers at Penn State may have a solution in the form of a micro microbial fuel cell, which can be powered by saliva.
Microbial fuel cells take advantage of the small amount of electrical charge bacteria produce as they process organic material. By capturing that charge with an anode, it can be run through a circuit to power a device. Microbial fuel cells have been developed before, and often use wastewater, but this new cell is able to operate off of the organic material found in saliva. It further differs from other microbial fuel cells by only using a single chamber with a graphene coated, carbon cloth anode. Other fuel cells possess two chambers and use platinum. Another important difference is it utilizes an open-air cathode, and the researchers do not quite understand why. Normally if oxygen is able to reach the bacteria, no electricity will be produced, but it works in this case, possibly due to the electrodes being microns apart.
Potentially this and similar microbial fuel cells could power devices to measure glucose levels and other useful pieces of information. They may not put out even a full microwatt, but not much is needed for some of these devices.
Source: Penn State
Posted: April 8, 2014 06:10PM
In most of our day to day lives, losing some time due to inaccurate time pieces probably does not amount to much more than a narrowly missed bus. For many systems we rely on every day though, losing even a fraction of a second can cause problems. To help prevent that from happening, NIST has launched its newest atomic clock; NIST-F2.
Like NIST-F1, which is still in use, NIST-F2 is a cesium atomic clock, which means they both measure the vibrations of cesium atoms to count time. This makes sense as the second is actually defined as 9,192,631,770 vibrations of a cesium atom. The new clock is significantly more accurate though, to the point that over the course of 300 million years it should neither gain nor lose a second. This improved accuracy in part comes from it being kept at the low temperature of 80.15 K. This reduces the effects of external radiation sources that can causes errors with NIST-F1, as it operates at room temperature.
Part of NIST-F2's purpose will be in reporting to the International Bureau of Weights and Measures, which uses atomic clock data to set Coordinated Universal Time (UTC) and according to its data, NIST-F2 is now the world’s most accurate atomic clock. It will also be used to help calibrate commercial atomic clocks, which have uses in the power grid, stock markets, and global positioning satellites.
Posted: April 8, 2014 07:22AM
Being comfortable is important, but it is not always possible, depending on the situation, so people are constantly trying to find ways to fix that. One area that could use some work is medicine as many sensors for monitoring vital signs are uncomfortable or sacrifice ability for comfort. Researchers at the University of Illinois, Urbana-Champaign however have developed a stick-on patch that can have off-the-shelf electronics built into it.
The patch itself is like an elastic envelope, filled with fluid and the electronics. Of course the chips are rigid, but by using a squiggly pattern, the wires that connect them are able to survive stress without fracturing. No matter which way the stress is directed, the wires are able to unfold and continue functioning. This design is so that the patch can survive being adhered to a person's skin, without uncomfortable pulling.
When the researchers tested this patch against traditional EKG and EEG monitors, it performed equally well. As this patch design is compatible with off-the-shelf electrical components, the technology can be used pretty cheaply, especially compared to similar patches with specially-designed components.
Posted: April 7, 2014 02:02PM
When in a new environment, or lost in an old one, we will do the natural thing of picking out landmarks to help us keep our bearings. For humans this is natural, but for robots and computers, such a process is quite difficult. Researchers at MIT though have devised a new algorithm to help robots find their way.
One of the reasons robots have such difficulty tracking landmarks to orient themselves is that they have a hard time identifying the orientation of the landmark to begin with. The researchers' algorithm addresses this by mapping estimates for the orientations of points onto a sphere. As a robot moves in one direction, the sphere will rotate in the opposite direction, allowing the robot to follow how the landmarks change. As the estimates are not going to be perfect and will cluster together, the algorithm forms Manhattan frames, which are sets of axes within the sphere. It is these axes that the robot follows, as they should be more accurate than the individual points, and simpler to operate on than a multitude of points.
This algorithm is also useful in achieving plane segmentation, which a computer does to determine what planes elements in a scene are in, as there are fewer orientations to consider. This is used to build representations of the objects to compare to reference objects.
Posted: April 7, 2014 06:31AM
Mobile communication has become an important part of our lives, so secure mobile communication is of vital importance. Personal and sensitive information, such as passwords and account numbers are exchanged between our mobile devices and remote servers over the air, and securing it can be difficult due to the small size of mobile devices. Researchers at the University of Bristol though have demonstrated a means to bring quantum cryptography to mobile devices, without adding too much bulk.
Quantum cryptography is a security system that takes advantage of the sensitivity of quantum systems. These systems are so fragile that even the act of observing them can change them, which is what the cryptographic protocols use. By transmitting an encryption key between two parties with quantum particles, such as photons, they can both be alerted to a third party listening in, as the particles will have been affected. The technology to create those particles though is typically too bulky to be integrated into a mobile device. The Bristol researchers however have developed a protocol that need only have an optical chip built into the device.
With such a protocol it would become almost impossible for a hacker to pull your information out of the air. Now the researchers are just working on bringing the protocol out of the lab and into a real device.
Source: University of Bristol
Posted: April 4, 2014 06:55AM
Violence in video games is nothing new, but it has been changing along with the technology that drives the games. The tolerance of the virtual violence has also been changing, and according to researchers at the University of Missouri, Columbia the tolerance has actually increased with the realism of violence, instead of decreasing.
For their study, the researchers examined the issues of GamePro Magazine released in the 1990s, as it was the most popular video game magazine at the time. They found that in the beginning of the decade, the journalists showed a great deal of concern over the violence in the video games they covered. As the decade continued, and more powerful game systems were released, this concerned lessened, despite the increasing realism of the depicted violence.
The researchers suggest some reasons for this inverse relationship. One is that as gamers matured, so did their tolerance of the violence, and the journalists reflected this in their writings. Another is that the video game rating systems we use today enable a defense against criticisms of violence, as anyone can be informed of a game's content. Finally the researchers also point out that society has changed over the years, developing a greater interest in violence, with more R rated films and violent music being released.
Source: University of Missouri, Columbia
Posted: April 3, 2014 01:36PM
As a situation changes, it is useful for systems to be able to change as well and adapt to the new state. Depending on the system though, this may not be easy or even possible, but there is a chance someone is working to change that. Researchers at the University of Bristol for example have recently found a way to alter a phononic crystal in real time, which could lead to some interesting new devices.
The phononic crystal in this study is actually a collection of colloidal, metamaterial crystals. Metamaterials are materials with properties not possible in Nature, and being colloidal means these crystals are actually in a liquid suspension. This combination gives the larger phononic crystal special properties and the researchers the ability to manipulate it, and even change how those properties are expressed. That manipulation comes by applying the proper acoustic wavelength to the crystal.
Potentially this phononic crystal could be used to create acoustic barriers that can be changed to best respond to whatever sound is striking it. The research could also be applied to other colloids, granting control over their properties cheaply and in a manner that could be easily integrated into other systems.
Source: University of Bristol
Posted: April 3, 2014 06:49AM
Humans have been thinking about invisibility for thousands of years, but only recently has the technology to make it possible been near reality. Metamaterials could be used to construct an invisibility cloak, but they are difficult to build that we still cannot cloak large objects. Researchers at the University of Central Florida though have found a way that may open the door to manufacturing large-area metamaterials.
One of the interesting consequences of physical laws being mathematical formulae is that they can often be ways to manipulate the math to something beyond what is found in Nature. Metamaterials are materials that have those properties that do not exist naturally, such as negative indices of refraction. Using metamaterials it is possible to direct light, and other waves, around an area, making it appear that nothing is within that area, thus creating an invisibility cloak. As metamaterials have very special structure to them, it can be prohibitively difficult to hide large areas, but using nanotransfer printing could change that, according to the UCF researchers. This fabrication method operates by creating metal/dielectric composite films and stacking them into a 3D architecture. With enough precision the new material can have the structure needed to act as a metamaterial.
With more work, the researchers hope to improve the fabrication process enough to build large pieces of metamaterials that can be used for real-life applications. The number of such applications is almost limitless as any instance of controlling waves could benefit, from stealth technology to wireless communication.
Source: University of Central Florida
Posted: April 2, 2014 02:53PM
Being able to learn and teach what we learn is critical for humanity to survive, and it is also tricky to do right as the ultimate desire is for the student to surpass the teacher. Computers too, have a need to learn from each other and pass on skills, and now researchers at Washington State University have succeeded in programming computers to behave like a teacher and student pair.
In this case, the computers were given the tasks of playing Pac-Man and a version of StarCraft. The teacher aided the student by giving action advice, so the student knew when to act. To keep it realistic, an algorithm was developed to direct when advice is to be given, as constantly giving advice will just frustrate the student and not giving advice is not teaching. Eventually the student was able to outperform the teacher, just like with humans, though they were still pretty dumb.
While it may seem silly to give computers the ability to teach each other, as a hard drive can just be swapped from one machine to another, differences in hardware and software could cause problems. Next the researchers are working on curriculums for the computers, so hopefully they can advance from simple to more complex work.
Source: Washington State University
Posted: April 2, 2014 08:22AM
The ability to selectively filter light is invaluable for many systems, and we have ways of doing so based on the light's frequency or polarization. Filtering light based on its direction however, has been proving difficult. Researchers at MIT though have successfully achieved just that with a precisely engineered mirror.
This mirror is different than what you may find in your home though because it is made up of many ultrathin layers of two materials, alternating between them. At the interfaces between the layers, some light will be reflected, but at what is called the Brewster angle, there are no reflections and light is able to pass through. Previous research has demonstrated selectively reflecting light based on angle, but that was limited to a smaller range of frequencies, while this approach is able to reflect the entire visible spectrum.
With the current design, the selectivity is limited to a range of about ten degrees, but by adding more layers it should be possible to shrink that. Potentially this research could be used to improve solar thermophotovoltaics, where controlling reflections is important, and to create displays with viewing angles limited to those directly in front of them.
Posted: April 1, 2014 08:47AM
To produce the electronics we use every day requires specialized nanofabrication processes to etch the correct structures into a material. Among the steps involved is developing materials called resists, and this requires toxic chemicals. Researchers at Tufts University may be changing that in the future though, as they have found that silk can be used as resists, and that water can develop it.
The fabrication process starts with a substrate that a resist is applied to, and currently that resist is a special polymer. Next a beam, either of light or an electron beam is used to place a pattern on the resist. The resist must then be developed, which may remove the patterned areas or keep them, depending on the situation, and this development requires toxic chemicals. If silk is used as a resist though, then only water is needed to develop it.
By replacing the toxic chemical with water, semiconductor and other nanofabrication complexes can reduce the amount of toxic waste they produce. This is definitely a benefit to those who work in clean rooms and the environments around them.
Source: Tufts University
Posted: March 31, 2014 01:02PM
While many of us may primarily see paint as a cosmetic product, it can be critical to a material's long life. One example would be the steel hulls of Navy ships, which are constantly exposed to harsh elements, including sea water. Since 2008, researchers at the Office of Naval Research and John Hopkins University have been working on an additive to allow paint to heal itself, and extend its protection.
The researchers are working with polyfibroblast, which is a powder made of microscopic polymer spheres. When the spheres are broken, a resin is released and that will form a water-repellant coat over any exposed steal. This is not the first self-healing paint, but unlike those that exist now, it is being designed for tactical vehicles, and not with aesthetics in mind. It has already been tested in a laboratory setting and successfully prevented rusting for six weeks in a salt fog.
Every year the Department of the Navy spends roughly $7 billion dealing corrosion, and the hope is that adding polyfibroblast to the primer could make significant cuts into that. It could also be used to extend the life of a deployed vehicle in the field.
Source: Office of Naval Research
Posted: March 31, 2014 08:00AM
It can be easy to forget as we read about any number of products just what went in to creating them. For some products, the materials they contain were mined and for others they were synthesized, but either way there are some costs and risks involved. Researchers at North Carolina State University have recently found a way to reduce the cost and risk of producing vertically aligned carbon nanofibers by replacing ammonia with ambient air.
Typically producing vertically aligned carbon nanofibers (VACNFs) involves placing nickel nanoparticles on a substrate, within a vacuum chamber. The chamber is then heated to 700 ºC and it is filled with ammonia and a carbon containing gas, such as acetylene or acetone. A voltage is then applied to the substrate and an anode, which ionizes the gas and frees carbon atoms to grow nanofibers beneath the nickel. The purpose of the ammonia in this process is to prevent the nickel nanoparticles from becoming encrusted with carbon, which would stop the nanofiber growth. Even though they did not expect much to happen, the researchers decided to repeat this process, but with ambient air replacing the ammonia. To their surprise, the VACNFs that grew are similar in size, shape, and alignment to those grown with ammonia.
While ammonia gas is not particularly expensive, it is toxic so removing it from the process could make the process of growing vertically aligned carbon nanofibers much safer. Potentially it may even lead to growing them without the use of a vacuum chamber, which would allow them to be grown on a much larger scale than presently possible.
Source: North Carolina State University
Posted: March 28, 2014 08:20AM
For some time now, manufacturers have been turning out multi-core processors, which offer improved performance without having to increase clock speed. Taking advantage of that performance with parallel programming is difficult though, especially as you try to optimize the execution of commands. Researchers at MIT however have found that one optimization method may be better than is generally thought, which could make parallel programming easier.
Parallel programming requires a programmer to properly split tasks between computational cores, and the longer it takes to complete any one of those tasks impacts how quickly the program can be run. Lock-free algorithms promise the programmer that at least one core will complete its task within a certain amount of time, and while that is helpful, its worst case scenario wastes potential. This is why many are working with wait-free algorithms that guarantee all cores finish a task within a fixed time, but these are much more difficult to develop. The MIT researchers have found that while the worst case for lock-free is not very good, on average it is much better than that and even rivals wait-free algorithms. They discovered this by using a random chip scheduler that assign resources to any task based on a probability, instead of priority.
This result suggests that programmers could save themselves some time by coding with lock-free algorithms, as the performance difference between them and wait-free algorithms need not be that great. However, as lock-free algorithms still have a bad worst case scenario, a programmer should still consider what the application for the code is.
Posted: March 27, 2014 12:14PM
The Earth is filled with an almost unimaginable variety of organisms, from majestic elephants and whales, to slime molds. With the proper ingenuity, we can put these organisms and their special abilities to use in unexpected ways. As reported by Elsevier, researchers have successfully built logic circuits with slime mold networks.
Physarum polycephalum typically inhabits dark and damp areas, and when it is in its plasmodium state, the slime mold will stretch a network of tubes across its environment. These tubes are meant to bring nutrients into the mold, but they also allow it to respond to environmental conditions and release spores. By placing nutrients to attract and salt to repel the tubes, the researchers were able to control the structure of the network as it grew. They then gave the mold dyes, which they have previously shown it could absorb and transport, which contained magnetic nanoparticles and fluorescent beads, creating a biological lab-on-a-chip device.
By increasing the size of the network it should be possible to have the slime mold network perform the complex Boolean operations, and already XOR and NOR have been demonstrated. While it is unlikely we will see slime-based computers in the future, this could help merge materials science, computer science, and biology.
Posted: March 27, 2014 07:11AM
Many people are looking forward to the day that quantum communication can be used to securely share information with another party. While that may sound great, there is a limitation to many of the current approaches, as only two parties can communicate with each other securely. Researchers at the University of Waterloo however have successfully entangled three particles, and this research could one day allow additional parties to be networked together.
Quantum entanglement involves having the properties of multiple particles so strongly coupled that measuring one can inform you about the state of the others. This is true no matter how separated the particles are. Typically only two particles are entangled, but by putting three photons in a Greenberger-Horne-Zeilinger (GHZ) state, all three particles were coupled and entangled. At this point the researchers placed one photon in a long optical fiber while the other two were sent to two trailers, 700 m away. This is far enough that the researchers were able to rule out that any information was being shared between the particles, when taking their measurements.
Previous work with quantum communication always focused on connecting pairs of particles, but with this we can start thinking in terms of multiple particles and a network of parties. Multipartite protocols will have to be developed to take advantage of such networks, but it will be interesting to see what is ultimately made possible.
Source: University of Waterloo