Science & Technology News (768)
Posted: January 29, 2015 02:50PM
For decades now we have relied on electronics, and while they have served us well, the time is approaching that we replace them with something else. One of these potential replacements is spintronics, which relies on the spin of electrons to store information, but it may be getting some new competition soon. Researchers at Berkeley Lab have made an important discovery that could give valleytronics the boost it needs to challenge spintronics and bring us closer to a quantum future.
Valleytronics is similar to spintronics in that it uses a quantum value to encode information, but the value has a different source. It comes from electrons moving through a 2D semiconductor as a wave with two energy valleys. These valleys can be described by their momentum and quantum valley number. What the Berkeley researchers have discovered is a way to generate a pseudo-magnetic field for controlling the valley excitons, using the optical Stark effect. Manipulating these excitons is hard to do with real magnetic fields, even when using superconducting magnets. The optical Stark effect creates the powerful pseudo-magnetic field with laser pulses.
Both spintronics and valleytronics offer significant improvements in data processing speeds over modern electronics, so it will be interesting to see which may be adopted in the future. Either one though will likely open the way to quantum computers.
Source: Berkeley Lab
Posted: January 29, 2015 06:02AM
Light is central to many technologies we rely on today, but it is likely to become even more important in the future. Before that can happen though, we must find new ways to manipulate light into doing what we want it to do. Researchers at the University of Illinois have recently succeeded in demonstrating Brillouin Scattering Induced Transparency (BSIT), which is a major step toward that level of control.
Normally you would expect light travelling through a fiber to continue on through it, but it can be made to leave the fiber by placing a microresonator next to it. What BSIT does is allow you to remove that opacity, and the researchers were able to trigger it by firing a laser at the microresonator. This second laser causes mechanical vibrations, which can be tuned to do more than just allow light to pass or not. The resonator can also cause light's group velocity to increase or decrease. This 'slow' light is useful for optical buffer applications, such as storing quantum information.
Another part of this discovery that is particularly important is that BSIT is non-reciprocal, meaning that this system was only allowing through from one direction, while it would still block light coming from the other. Current non-reciprocal devices are more complicated and are unsuited for use in optical chips, but this could actually be built into chips using current foundry processes.
Source: University of Illinois
Posted: January 28, 2015 02:35PM
For as long as humanity has had the idea that other planets exist in the Universe, we have been wondering if they may also support life. Today that curiosity is manifested in various missions to search out these planets, such as NASA's Kepler mission. Now researchers at Iowa State University and the University of Birmingham have discovered a very old star with at least five Earth-sized planets orbiting it.
Kepler-444 is the name of the star that is smaller than our Sun, but considerably older. It is actually among the first generation of stars in the Milky Way at 11.2 billion years old. The five planets observed orbiting it are between the sizes of Mercury and Venus and likely do not support any life due to how closely they orbit the star. The system is just some 117 light years away.
While the discovery of Earth-sized planets is always interesting, it is the age of this system that makes the discovery particularly important. It shows that planets have been forming for most of the galaxy's and Universe's life, and is not something requiring a more modern galactic environment.
Source: Iowa State University
Posted: January 28, 2015 06:14AM
Quantum entanglement is a phenomenon that many are interested in putting to work in our computers and networks, but doing so is easier said than done. One of the sources of difficulty is lack of a means to create entangled particles on a computer chip. That may soon be changing though, thanks to a paper recently published in The Optical Society's Optica journal.
To create entangled pairs of photons, the photons must have the ability to interact with each other, and normally that requires special photonic crystals. High powered lasers may also be necessary to feed photons into the crystals. Neither of these requirements are ideal when trying to bring entanglement into computers. The best solution would be something you could build directly onto silicon chips, and that is what the paper describes. The researchers made their discovery by starting with ring resonators, a structure already built on chips for telecommunications that are used to hold and emit photons. The researchers found a way to couple a laser beam with the resonator and create a system perfect for photons to become entangled.
The ring resonators come in at just about 20 micrometers, which is much smaller than the millimeter-scale entangled photon emitters, and require far less power to operate. An entangled photon emitter that can be built into silicon chips could help bring about quantum networks and quantum computers cheaply and efficiently.
Source: The Optical Society
Posted: January 27, 2015 02:12PM
Kevlar is a well-known polymer that has long been used in bulletproof fabrics, and thanks to researchers at the University of Michigan it may soon be protecting batteries. In this case though, it will not be protecting against bullets but electrical shorts.
As part of the normal operation of batteries, ions flow from one electrode to the other, which is fine unless the ions start building structures known as dendrites. These structures look like fern planets, grow off of one electrode, and if they reach the other, will cause a short, damaging the battery and potentially starting a fire. To prevent the dendrites from forming, a membrane is wrapped around the electrodes, but most membranes have a pore size a few hundred nanometers in size, while dendrite tips can be 20 nm to 50 nm. What the Michigan researchers have found though is that Kevlar fibers can be layered on top of each other to form a membrane with pores just 15nm to 20 nm wide; small enough to block the dendrites.
Along with being good for blocking dendrites, the Kevlar sheets are also very thin, which could allow batteries to be made smaller. The researchers have founded a company, Elegus Technologies, to bring this work to market, and they expect mass production to begin in the final quarter of 2016.
Source: University of Michigan
Posted: January 27, 2015 07:15AM
Chances are that if you have a flat screen display of some kind, indium tin oxide (ITO) is part of it. That is because ITO is highly conductive and transparent, but it is also expensive so many have been search for alternatives. One contender is silver nanowires, but its mechanical properties must be better known first. To that end though, researchers at Northwestern University have made an interesting discovery.
Along with being conductive and transparent, silver nanowires embedded in a polymer would likely also be flexible. Just because they are flexible though, does not mean they will not be fatigued by stress and eventually fail. To test the material the researchers used cyclic loading, which changes the stress on the material, and observed any changes using an electron microscope. What the researchers found is that some of the permanent deformation to the nanowires actually recovered, meaning it has some self-healing capability.
This finding is critically important for determining if and how silver nanowires may be used in the future. The next step is to see how well the nanowires survive being flexed millions of times, and how the self-healing behaves under those circumstances.
Source: Northwestern University
Posted: January 26, 2015 02:10PM
Just about anything that can be done, can be done multiple ways, which begs the question of what the best way is. Depending on what is being done, the answer may be very difficult to find. Thanks to researchers at MIT, we now have a much better understanding of one way to find the answer.
To start optimizing a problem, a cost function describing it must be generated. Depending on the function's complexity though, finding the minimum can be very difficult, so a common practice is to work with a similar but simpler function. Once that function is solved for, some complexity is added back and the previous solution used to find the new one. While this method works, it has not been theoretically described and knowing what simpler function to start with is difficult. What the MIT researchers have done is developed an algorithm that finds the simpler function. It works by making a convex approximation of the original function using Gaussian smoothing. This smoothing creates a new function where each value is actually the weighted average of values from the original cost function, and the weighting follows a normal curve. By shrinking the normal curve, the smooth function approaches the original function until it exactly matches.
This approach removes the guesswork that would otherwise be involved, making the optimization process more straightforward.
Posted: January 26, 2015 06:18AM
The ability to control phenomena is important for many current technologies, and certainly many future ones. For example, controlling the emission of photons is necessary for future telecommunication devices and photonics. Researchers at the Institute of Photonic Sciences, MIT, and more have recently demonstrated control of photon emission and plasmon creation using just electrical voltages.
For their work, the researchers began with photon emitters made of erbium that were placed on a graphene sheet. The carrier density or Fermi energy of that sheet is electrically controlled. Normally erbium ions are used in optical amplifiers and can emit light at 1.5 micrometers, which is useful for telecommunications as there is little energy loss at that wavelength. Energy was fed into the erbium, causing electrons in the graphene sheet to become excited. As the Fermi energy of the sheet was increased by applying a voltage, the erbium ions started emitting photons or plasmons. Plasmons are a combination of photons and electrons with great potential in telecommunications, and researchers have long been looking for a way to create them in graphene, at near-infrared frequencies.
This control of emissions could be used to improve current communication technologies, as well as sensors and displays, but could also be put to use in new devices. It could even be used for data storage and to make active plasmonic networks.
Posted: January 23, 2015 02:54PM
According to Newton, objects will not accelerate unless an unbalanced force is applied to them. While that is still true, researchers at MIT and Israel's Technion have found a way to trick Newton, and the conservation of momentum. What they discovered is a way to cause an electron to accelerate on its own, almost to the speed of light.
The researchers theorize that this effect can be caused with specially engineered phase masks, like those for creating holograms but at a much finer scale. Any electron that is self-accelerated this way, would look like it were accelerated by some external force, even though none is being applied. The reason this does not violate any laws of physics is because the electron is accelerating and expanding at the same time. The tail of the electron's wave packet expands backwards so that the total momentum is still preserved.
As the researchers dug into their theory more they also found that the self-acceleration can cause time dilation, like that described by relativity. This could be especially useful by allowing a way for short-lived particle to exist a little longer, making it easier to study them.
Posted: January 23, 2015 06:48AM
Wormholes have been a popular topic in science and science fiction for decades and could potentially allow for relatively easy travel across the Universe. While they have been theorized though, no one has found one yet, but one has been suggested. Researchers at the International School for Advanced Studies have theorized that our home galaxy, the Milky Way, may actually be a gigantic wormhole.
To arrive at this idea, the researchers combined equations from General Relativity with a highly detailed dark matter map of the galaxy. Based on the observed dark matter distribution, the Milky Way might not only contain a worm hole but have one spanning its full size. It could even be navigable, if the researchers' calculations are correct.
To test if the hypothesis is true, one will have to very carefully compare the Milky Way with another galaxy, which is something we are not yet capable of. Besides that hypothesis though, this work could also lead to new interpretations of what dark matter is.
Posted: January 22, 2015 02:10PM
Metamaterials are likely among the most important, recent scientific discoveries as they are able to defy Nature and give us properties that cannot be found in any natural material. A lot of the research into metamaterials has concerned optics, and especially the possibility of creating invisibility cloaks, but this is not the only application. Another potential use is to enhance light sources, and recently researchers at City College of New York have done this.
Previous efforts to enhance light emission with a metamaterial have been problematic because the light did not want to leave them. For this work the researchers put a light emitting nanocrystal on top of a metamaterial with hyperbolic dispersion. This would enhance the light emission, and then the researchers figured out how to efficiently extract the photons from the system by embedding quantum dots in the material.
Potentially this discovery could lead to ultrafast LEDs, nanoscale lasers, and efficient single photon sources.
Source: City College of New York
Posted: January 22, 2015 06:41AM
For some, keyboards are just an input device, but for others they are a work of modern technology with advanced switches, layouts, and software driving them. As impressive as your keyboard may be though, researchers have created one that is probably some notches above. This new keyboard, as reported in the journal ACS Nano has the ability to identify users, providing extra protection against direct access of a computer by an unauthorized user.
The smart keyboard identifies users by recognizing the pressure we apply to keys as well as the speed with which type. With such a profile, even if someone inputs the character password, the keyboard can still prevent successful access. The keyboard is even able to power itself or a small device from the energy of each key press. It is also dirt resistant as its surface coating repels dirt and grime.
Source: American Chemical Society
Posted: January 21, 2015 02:40PM
Organic semiconductors have been a focus of a lot of interest for some time now, as they have the potential to very cheaply replace silicon-based devices, and introduce new properties. While they have that potential, it is difficult to tap it because of uneven performance issues. These issues have been known about for some time, but finally we may know what causes them, thanks to researchers at Berkeley Lab.
Inside of organic semiconductor films are nanocrystals that form domains. Researchers have realized the performance issues come from the domain interfaces, but the exact reason why has eluded them. This is in part because the domains are so much smaller than the diffraction limit that few observation methods would work. The Berkeley researchers solved that problem by adapting transient absorption (TA) microscopy to work with the samples of TIPS pentacene they had. This method uses femtosecond laser pulses to excite transient energy states, and then measures the changes in the absorption spectra. The researchers modified their system to create focal volumes a thousand times smaller than normal TA microscopes achieve, and made it possible to use different light polarizations, to isolate signals from adjacent domains.
What the researchers found was that the problem comes from the smaller domains between larger ones. These smaller domains can have random orientations that prevent charge carriers from moving efficiently. Armed with this knowledge and an ability to measure and predict performance, it should be possible to optimize the systems for manufacturing organic semiconductors.
Source: Berkeley Lab
Posted: January 21, 2015 06:59AM
Hydrophobic materials have been of interest for quite some time, and so has ways of making arbitrary materials super-hydrophobic. Researchers at the University of Rochester have achieved the latter, to a point, by finding a way to make metals super-hydrophobic using lasers. This discovery could have many applications, including improved water collection, ice protection, rust prevention, and even improved sanitation.
One common way to make a material super-hydrophobic is to apply a coating to it of something that already is. While this can work in some situations, the coating may wear out in time and even fall off, making it less than ideal. What the Rochester researchers have done is used a femtosecond laser to etch a pattern of nanoscale and microscale structures onto a metal's surface. These structures are what prevent water from sticking to the surface. When tested, water drops actually bounced off of the metal. While the water may not stick to the surface, it does still impact it, which gives the metal some self-cleaning capabilities as dust and dirt will be pulled off by the water.
Now the researchers are working to see if they can adapt this method to materials other than metals. They are also working to speed up the patterning process, as it currently takes an hour to cover a square inch, which is too slow to keep the metals cheap and accessible to everyone.
Source: University of Rochester
Posted: January 20, 2015 02:45PM
Lasers are amazing pieces of technology that are in many of our devices, and used in the manufacture of many more. Naturally many future technologies will rely on them, but before some of them can be realized, certain issues must be overcome. Researchers at Yale University may have found a solution to the problem of speckle by using a new kind of laser.
With their brightness, lasers are ideal for many imaging technologies, such as microscopes, holography, and photolithography, but they can also corrupt the images they are being used to create. This corruption comes from speckle, which is a grainy pattern caused by the high spatial coherence of the light. In some situations LEDs can be used, as they have lower speckle, but they are also far less bright, making them a poor fit for high-speed imaging. What the Yale researchers developed exhibits the best of both technologies and is based on a chaotic cavity laser. Random and chaotic lasers normally have no known applications, but the researchers decided to work with other disciplines to see if there are any problems they could solve.
Typical lasers have a speckle contrast of 50%, but it needs to be less than 4% for full-field imaging. The new semiconductor laser comes in at just 3%, which makes it perfect for future imaging technologies that need speckle-free and bright light sources.
Source: Yale University
Posted: January 20, 2015 05:43AM
I do not know how many electrons are currently coursing through my computer and monitor as I type this, but I expect it to be a lot, because that is how many it takes. The idea then that anything could be powered by a single electron seems a little crazy, because normally you need so much more. As it turns out though, it is possible for a single electron to power some systems, as researchers at Princeton University discovered, when working on how to put double quantum dots to use.
Quantum dots are semiconductor nanocrystals that are sometimes referred to as designer atoms or molecules, because their properties can be so well tuned. Double quantum dots are just two of them joined together, and they may see use as qubits in quantum computers, but first we need them to communicate with each other. To achieve this, the researchers made the dots into lasers, so that the photons they emitted could bounce off of mirrors, creating a coherent beam, and entangle each other. The laser works by having electrons, one at a time, tunnel through the quantum dots, and drop in energy as they do so, releasing a photon in the process. The reason the electrons are going one at a time is because the quantum dots can only hold one at a time.
Unlike traditional lasers, the frequency of light emitted can be tuned here, by controlling the energy levels the electrons jump between. This work could lead to new light sources in the future, and potentially more as it shows a way to control the movement of even a single electron.
Source: Princeton University
Posted: January 19, 2015 07:38AM
One of the latest goals in display technology has been 3D images, so that viewers can get a deeper sense of what they are seeing. The ultimate goal many are working toward is a 3D display that can achieve this without requiring the viewer to where special glasses. Researchers at the Vienna University of Technology and TriLite Technologies have recently made a prototype display capable of just that.
To create a 3D image, different images need to be sent to both of our eyes at the same time, as the differences give us the sense of depth. Normally this is achieved with polarized light and glass that have different polarizations for both eyes. This new technology instead directly sends different images to our eyes using a sophisticated laser system. The laser is aimed at a moveable mirror, which directs the light across the field of vision, and by modulating the intensity of the laser fast enough, our two eyes can see two different images. This also allows for the display to show multiple, 3D images as one walks around it, like with a real object, and if used in a billboard, could show people in different places completely different images.
The prototype display the researchers built only consists of 15 3D-Pixels, or Trixels, but the researchers say that scaling the technology up is not a problem. In fact they expect to have a second, larger prototype completed in the middle of the year, and a commercial launch in 2016.
Source: Vienna University of Technology
Posted: January 16, 2015 02:11PM
Electricity and magnetism are central to the operation of many computers, but they have their own advantages and disadvantages. One way to potentially overcome the issues of both is to use multiferroic materials, which have both ferroelectric and ferromagnetic properties and could lead to low-power, nonvolatile memory devices. The catch is that these materials are very difficult to integrate into computer chips, but researchers at North Carolina State University have made a pair of helpful advancements.
One of the multiferroic materials used consists of barium titanate (BTO), a ferroelectric material, being layered with lanthanum strontium magnese oxide (LSMO), a ferromagnetic material. This pairing cannot be integrated into silicon chips though, because materials would actually diffuse into the silicon. The researchers found that they could remove the LSMO though, by using a laser to create oxygen vacancy-related defects in BTO, giving it the necessary ferromagnetic properties. The researchers then found that if a crystal of titanium nitride (TiN) is grown on the silicon, and a crystal of magnesium oxide (MgO) grown on top of that, they would act as buffer layers to the multiferroic material, preventing the diffusion.
The researchers have used this work to create prototype memory devices with integrated multiferroic materials, which they are now testing. Once that is done they will be looking for industry partners to bring this work to manufacturing.
Source: North Carolina State University
Posted: January 16, 2015 05:41AM
In many ways the future of computing will rely on materials science, as new materials will be necessary to achieve the desired increases in power and efficiency. Nanowires are one example of this but they come with a problem of how they connect to an electrode. Researchers at the Niels Bohr Institute, however, have found a solution to this that also opens up new possibilities.
Normally nanowires and their electrical contacts are made separately and then connected. What the researchers have done is find a way to grow both the semiconducting nanowires and the metal contacts together. This causes the transition between them to be as perfect as you can get, with the atoms themselves lining up in both materials. It also turns out that when brought to low temperatures, the interface will become superconducting, which could prove useful in future electronics.
Besides the possible improvements to performance, the perfect transition can also be used to more precisely study its electrical properties. The researchers believe these nanowires could one day lead to superconducting electronics, but already they have built a chip with billions of identical nanowire hybrids.
Source: Niels Bohr Institute
Posted: January 16, 2015 03:08AM
Author: Brentt Moore
Logitech has publically announced that an open API is now available for its Harmony platform, which allows users to combine and control lights, locks, thermostats, blinds, music, movies, TV, and more to create customized home activities. According to Logitech, its Harmony products are already connected to more than 270,000 devices from manufacturers such as Apple, Honeywell, LG, Lutron, Nest, Philips, Roku, Samsung, and Sony. By making the Harmony API available to developers of other platforms and devices, Logitech in ensuring that users of Harmony devices will successfully be able to utilize it to control even more aspects of their home. Mark Spates, the manager of the Harmony platform for Logitech, notes that "By opening our platform to developers, we’re giving developers the ability to create complete smart home experiences."
Posted: January 15, 2015 03:12PM
Last month Rice University revealed a way to make graphene very easily with a laser, and speculated that it could be used to build supercapacitors. Now they have actually built the supercapacitors that are stackable, which is important for potential mass production.
Supercapacitors are devices that possess some of the better qualities of batteries and normal capacitors. Like batteries they have great energy storage, and like normal capacitors, the can be quickly charged and discharged. Normally graphene would make for poor supercapacitors because it conducts electricity so easily that a charge could not build up. The laser-induced graphene (LIG) however is filled with imperfections that can hold onto charges. To create these new LIG supercapacitors, the researchers start by creating the graphene on one side of the polymer film used, and making more on the opposite side. These pieces are then vertically stacked, with solid electrolytes between the layers, creating multiple microsupercapacitors.
When tested, these supercapacitors survived thousands of charge/discharge cycles without any loss of capacitance, and even endured 8000 bending cycles without degradation. Thanks to the ease of making LIG and the simple design of these supercapacitors, we could see this technology being mass produced with roll-to-roll methods someday.
Source: Rice University
Posted: January 15, 2015 06:44AM
So many of the technologies around us rely on batteries in one way or another, which is why so much work is being done to improve the technology. There are several avenues being investigated currently, but many have one issue or another holding them back. One example would be electrodes that contain vanadium pentoxide, but researchers at ETH Zurich have recently found a way around the problem.
The reason researchers are looking at vanadium pentoxide (V2O5) is because it can hold three lithium ions at a time, which is three times more than modern electrodes do. The problem is that when it absorbs these ions, the material swells enough that when the ion leaves, the material can fail. What the researchers did to get around this problem was add lithium-borate (LiBO2) to the mix, heat it to 900 ºC and rapidly cool it, forming a glass. While the normal crystal structure of V2O5 lacks stability when absorbing lithium ions, the disordered structure of the glass is more resilient.
When tested the new electrode performed well for about 30 charge/discharge cycles, but that increased to over 100 cycles when it was coated in reduced graphite oxide (RGO), to enhance its properties. One of these RGO coated electrodes allowed a battery to reach performance numbers that were one-and-a-half times better than modern batteries.
Source: ETH Zurich
Posted: January 14, 2015 02:09PM
Since graphene was discovered, researchers have been working on applications for it and on ways to replicate its extraordinary abilities. At the University of Exeter, researchers found in 2012 that putting a layer of ferric chloride (FeCl3) between two layers of graphene resulted in the best known transparent conductor. Now they have found that GraphExeter, as they have named the conductive, flexible, and transparent material, is also highly stable.
No matter how amazing a material's properties are, if it cannot survive certain conditions, it is not going to be useful in certain environments. Graphene, though strong and flexible, does have some weaknesses here, but apparently GraphExeter does not. When the researchers tested it, they found it could endure a relative humidity of 100% for 25 days at room temperature, or up to 150 ºC in air or 620 ºC in vacuum.
This survivability would be very useful in smart windows and solar panels, which have to survive a range of extreme conditions, and replace indium tin oxide as a transparent conductor. It could also be put to use inside nuclear power plants and have applications in space.
Source: University of Exeter
Posted: January 14, 2015 06:46AM
In order to one day have quantum computers we have to develop a variety of advanced and precise technologies, like photon optical chips containing single photon detectors. While such chips have been made, they are not very good at actually catching the single photons, in part because very few of the detectors on the chip will be any good. Researchers at MIT have found a fairly clever way to improve the numbers and make the detectors up to 100 times more accurate.
Typically the single-photon detectors are built directly on the silicon optical chip. This new method however allows the chip and detectors to be built separately and combined, so the best manufacturing methods can be used for the different components. The method starts with a film of silicon nitride, which is flexible, and then niobium nitride, a superconductor, is deposited onto the film, with gold electrodes at the ends. Now a droplet of polydimethylsiloxane is put on the film, and a tungsten probe pressed into it. Very quickly, the probe is pulled up, taking the polydimethylsiloxane and film with it. Now the film, with the photon detector on it, can be attached to a silicon chip.
Previous arrays of single-photon detectors would only register 0.2% of single photons sent to them, and even those deposited onto a chip individually have capped at 2%. The researchers' new chip was able to detect 20% of the photons though, and while it is still far from the 90% needed for a quantum circuit, it is a big step toward that goal.
Posted: January 13, 2015 10:40AM
How well do you know your friends? You may think you know them well, but it turns out computers can more accurately predict a person's personality than the people close to them. That is the finding from a recent study at the University of Cambridge that looked at Facebook Likes for these predictions.
To perform the study, the researchers had a sample of 86,220 volunteers on Facebook complete a 100 item personality questionnaire, and provide access to their Likes. The survey was to measure five psychological traits: openness, conscientiousness, extraversion, agreeableness, and neuroticism. These volunteers were then given the ability to invite friends or family to judge their psychological traits using a shorter version of the test. This resulted in a sample of 17,622 people judged by one person and 14,410 judged by two. For a coworker, the computer just needed 10 Likes to be more accurate, while a friend or roommate took 70, family member took 150, and it took 300 Likes for the computer to beat a spouse. Considering the average Facebook user has 227 Likes, computers could soon know us better than the people around us, at least in some ways.
The researchers believe that part of the reason the computer was so successful is because it is able to consider more information at once than a human, and is always ruled by logic. However, they also point out that humans still have the advantage when it comes to those without digital footprints or traits that rely on subtle cognition.
Source: University of Cambridge
Posted: January 13, 2015 06:07AM
Additive manufacturing, or 3D printing, is finding its place in more and more areas as it continues to be developed and improved upon. One example of such an innovation is the Big Area Additive Manufacturing (BAAM) machine at ORNL that is capable of printing objects larger than a cubic meter. To show off this capability, the ORNL researchers decided to print much of a car for the Detroit Auto Show, but not just any car; a Shelby Cobra.
It took six weeks to design, manufacture, and assemble the Cobra with 24 hours of print time. One of the improvements to the BAAM used for this work reduced the print bead size, giving a smoother surface to the printed pieces. They were still pretty rough though, so they had to figure out the best methods to give a smooth finish to the pieces and paint on them. The resulting vehicle weighs 1400 pounds, including 500 pounds of printed parts.
The hope for this technology is that manufacturers will use it to significantly speed up the process of prototyping cars, which is a process that has remained relatively unchanged for decades, and also reduce the costs. The Shelby itself will continue on as a laboratory on wheels, as it was designed to have components swapped out for testing new technologies, like batteries, fuel cells, hybrid systems, wireless charging systems, and more. The car will be on display at the auto show until January 15.
Source: Oak Ridge National Laboratory
Posted: January 12, 2015 02:34PM
Many modern technologies rely on two dimensional components, such as electronics that consist of flat components in layers. There is a great interest in moving to three dimensions though, as it could allow for greater capabilities, efficiencies, and more applications. Building 3D microstructures is hardly child's play though, but researchers at the University of Illinois at Urbana-Champaign are making it like a child's book.
Modern techniques for creating electronic circuits, build them in two dimensions. To bring them into the third dimension, the researchers use a soft substrate to pop them up, like a pop-up book. By pre-stretching the substrate and controlling where it binds to the semiconductor material, like silicon, it is possible to control the shape it will form. The stress the substrate puts on the semiconductor surface can then cause it to buckle and detach from the substrate, thereby popping up.
As these mechanical processes are already well understood, the whole thing can be modelled and designed with a computer to form any number of intricate shapes. Potentially this could be used to create devices for electronics, biomedical devices, microelectromechanical components, photonics, metamaterials, tissue scaffolds, and more.
Posted: January 12, 2015 06:46AM
It may be many years before we fully realize quantum computers, but some quantum technologies may be here much sooner, including quantum networks. In theory these networks would be able to send quantum information across the globe with unbreakable security. That data has to be stored though and quantum information tends not to survive long, but researchers at the Australian National University have set a record of six hours.
One of the ways currently used to store quantum information is with laser beams in optical fibers, and works with networks around one hundred kilometers long. This new method instead stores the information in the spins of europium atom nuclei, and preserves it by applying fixed and oscillating magnetic fields to the crystal. These fields isolate the europium spins so that the information cannot leak away, which is how the new storage time record is 100 times the previous one. Compared to the laser method, someone could walk with the crystal and have it suffer less loss, for a given distance.
While this quantum optical hard drive could have a serious impact on quantum networks, it could also affect our understanding of quantum mechanics. The phenomenon at work for the networks, quantum entanglement, has never been tested at as great of distances as this method allows.
Source: Australian National University
Posted: January 9, 2015 04:52PM
If someone needs to trap light, often they will turn to mirrors or photonic crystals that will hold the photons in place. Last year though, researchers at MIT found a way to stop light by having it cancel out its own radiation fields. Now the team has figured out how this happens and what it could mean.
Central to this new method is the polarization of the light involved, as the light-trapping photonic crystals used actually change the direction of the polarization. The change is dependent on the direction of the light beam, which causes a vortex to form, similar to tornadoes and water swirling down a drain. This forms a singularity, or topological defect, at the center of the vortex, which traps the light at that point. To the researchers' surprise, this trapped state is actually rather robust, which makes it easier to create than many expected.
From this research it may be possible to create vector beams, which are a kind of laser that could be used for small-scale particle accelerators. It could also lead to ways of transmitting more channels through an optical fiber and super-resolution imaging.
Posted: January 9, 2015 06:21AM
Order can be very useful, especially when trying to build things, but achieving it is not always easy. Quantum dots are nanoscopic crystals that have properties that would make them exceptional for solar panels, but making them the same size is somewhat difficult. At least it was as researchers at MIT have now found a way to make lead sulfide quantum dots of uniform size.
In the nanocrystals, the lead and sulfur atoms are roughly one-to-one, but the researchers found that it is best to start with a 24 to 1 mixture. This leads to the uniform size, which is useful for creating films of the quantum dots, as dots of the same size will self-assemble into an ordered lattice. Also better control of the size of the quantum dots can improve their performance, as the researchers found that the distance between the centers of the nanoparticles impact the amount of time electrons remain excited. The shorter the distance the greater the diffusion length, and that means more time to put the electron to use.
The researchers also found that while uniformity improves diffusion length, an amount of disorder can improve energy diffusion. Small variations in the quantum dots’ sizes can also cause energy variations, and higher energy electrons will try to move to areas of lower energy. This gets them going sooner than if the energy plane were flat, speeding up the process.