Science & Technology News (70)
Posted: May 17, 2013 09:45AM
Lasers are a special kind of device and when they were first created, they opened a new world to scientists of many fields. Since that day they have evolved as techniques improved and new technologies replaced old. Now researchers at the University of Michigan have created a completely new kind of laser that technically is not a laser because of how different it is.
Originally 'laser' was not a word but an acronym standing for Light Amplification by the Stimulated Emission of Radiation. This new device however operates quite differently as it uses polaritons to generate the photons, instead of other photons. This technique was first proposed in 1996 and works by electrically exciting electrons to higher energy states, creating an exciton; an electron-hole pair. By carefully tuning the microcavity these excitons are in and subjecting them to a magnetic field, it is possible to couple them to a photon, making them into polaritons. What that translates to is that when the electron and hole recombine, they will release a photon of a specific frequency. This fails to meet the definition of a laser because one photon does not cause other photons to be released.
While it may not technically be a laser, it could eventually be used to replace them as it can operate using 1000 times less energy. Before we can see them being used in modern electronics and networks though, they will have to be redesigned to function at room temperature, as they currently require cryogenic temperatures.
Source: University of Michigan
Posted: May 16, 2013 10:50AM
Some people believe that in the future, man will be melded with machine to overcome our weaknesses. While there are definitely some efforts being made on advanced implants and prosthetics, some are looking to combine electronics and organisms in a different way. At MIT researchers have modified bacteria cells to act as calculators with the ability to perform the five geometric operations as well as logarithms.
This is not the first time that cells have been modified to perform calculations, but unlike many of those previous experiments, the MIT bacteria are analog instead of digital, which comes with many advantages. Analog signals exist on a continuum, so one signal can carry quite a bit of information, compared to a single digital signal that is either 0 or 1. This allows for simpler circuits, such as the square root circuit which only has two parts, compared to the digital equivalent that has over 100. Another important advantage for analog circuitry is that cells already respond to analog signals, so the circuits could take advantage of existing mechanisms.
The researchers created their calculator from just three basic parts and are now working to develop more parts, to potentially create a library of parts to be used in cellular circuits. Eventually this could lead to more advanced molecular sensors, gene expression, as well as cellular computation and actuation.
Posted: May 16, 2013 09:03AM
In many cases before a new technology emerged to conquer a market, it existed in a variety of forms with different advantages and disadvantages inherit to their separate designs and constructions. Quantum computers are currently going through this phase as new and fundamentally different architectures are made and tested. Researchers at the University of Vienna have recently built and tested a 'boson sampling' computer, which uses photons, a type of boson, and a complex optical network to perform calculations.
Photons, the quanta of light, are being considered for use in many quantum computer designs, thanks to the relative ease they can be made with and their very high mobility. The design the researchers created takes advantage of this mobility by putting them through a network with multiple paths available to the photons. While a classical particle will be limited to a single path, a quantum mechanical particle can enter a superposition and take multiple at the same time. By then counting the number of photons to exit each output of the network, the computer is able to complete a calculation.
This ability of quantum computers to utilize superposition gives them the power to perform computations that are nearly impossible with a classical computer. Ironically though, to confirm this boson sampling computer was operating correctly, the researchers needed a classical computer to verify the quantum computer's output.
Source: University of Vienna
Posted: May 15, 2013 12:03PM
For some time now the United States military has been utilizing Unmanned Aerial Vehicles (UAVs) for surveillance and occasionally as offensive platforms, because they can offer a number of advantages human piloted aircraft cannot. Among these advantages is great endurance, as UAVs do not get tired, but they can run low on fuel. At the Naval Research Laboratory though, a UAV with a special fuel source was able to stay in the air for 48 hours and one minute, shattering the previous record of 26 hours and two minutes.
The UAV is called an Ion Tiger and has at its heart a fuel cell that uses hydrogen to generate the electricity needed to power its systems. To set the previous record, the Ion Tiger used a tank of gaseous hydrogen at a pressure of 5000 PSI, but for the new record the researchers used liquefied hydrogen. Like most materials, hydrogen is denser in its liquid form, so more of it could be stored on the UAV, but it is more complicated than just filling it up with LH2. Hydrogen boils at 20 K, so the storage system had to be kept very cold to minimize fuel loss, and to optimize performance the researchers tuned the rate of hydrogen boiling off to match the vehicle's fuel consumption.
The researchers are now looking into advanced systems to manufacture LH2, which could be hard to come by in combat zones. Potentially an electrolyzer powered by solar or wind energy could be used to collect hydrogen from water, before it is compressed and refrigerated for use as a fuel.
Source: Naval Research Laboratory
Posted: May 15, 2013 08:45AM
Batteries have given humanity new ways to change our lives and our environment, especially lithium-ion batteries, thanks to their ability to store and produce large amounts of power, while being compact in size. As great as they are though, the batteries can have flaws that impair their performance and reduce their lifespan. Researchers at Purdue University though have found a very quick and effective way to catch these flaws during the manufacturing process.
Within lithium-ion batteries are two electrodes which are copper on one side and on the other is a paint-like substance. This substance is designed to capture and store lithium ions, which is how the battery is able to hold and release a charge. Imperfections in the paint, such as variations in thickness, air bubbles, and even an incorrect mixture can all affect a battery's performance, but all of these can now be detected. The researchers found that by flashing a xenon bulb on the copper side of the electrode, the opposite, painted side is heated. Imaging the heat distribution allows the researchers to discover any defects very quickly and before they could be a problem.
This quality control process takes less than a second and could have profoundly impact lithium-ion battery manufacture, but preventing poorer electrodes from being installed in batteries. Not only can these defects now be fixed on the spot, but potentially we could see them being removed from the manufacturing process, thanks to the information this process will provide.
Source: Purdue University
Posted: May 14, 2013 08:42AM
Without a doubt, steel is one of the most important materials in our species history as it allowed for the construction of skyscrapers, machines, and more. Its manufacture is also one of the largest industrial sources of carbon dioxide, constituting 5% of all of the world's CO2 emissions. Researchers at MIT though have found a way to possibly remove all CO2 emissions from the production of steel, and potentially other metals as well.
Ironically the solution the researchers developed to address this Earth-bound issue came from work concerning the Moon. With is considerably low mass, the Moon has no atmosphere to speak of, but if humans are ever to inhabit it, there must be an oxygen source. One method being considered is to release the oxygen from iron oxide in Moon dust. As iron oxide is the primary component of iron ore, which steel is made from, the researchers looked for a way to apply the method for steel production. The key was to find an electrode that could survive the temperatures of molten iron oxide while still conducting electricity. What they discovered was an alloy of chromium and iron, which are both inexpensive.
Along with zero CO2 emissions (replaced with oxygen emissions) the researchers found this method can produce very pure steel, which is a definite advantage to its adoption and use. One disadvantage though is its inability to produce the millions of tons of steel per year to be economical in large-scale plants. Instead, it may only find a home in smaller plants that only need to output hundreds of thousands of tons of steel in a year.
Posted: May 13, 2013 03:07PM
Last year researchers mathematically showed it should be possible to create a device similar to an invisibility cloak, but instead of redirecting light around an object, it would redirect heat. Now researchers at the Karlsruhe Institute of Technology have created such a cloak out of copper and a silicon material.
The design of this cloak borrows greatly from metamaterial cloaks, which cause light to bend around an object, instead of striking and reflecting off of it. As copper is a good conductor of heat and PDMS silicon is not, the researchers were able to design the circular device to conduct the heat in specific directions around it, while also controlling the speed of the heat flow. This allows heat to uniformly distribute from one edge to the opposite, but the area in the center is left untouched.
As the theory behind thermal cloaks is still quite new, researchers are not able to predict all its applications. However, they do foresee it being used with electronic components, such as microchips, to manage heat.
Posted: May 13, 2013 09:04AM
The most efficient solar power systems on Earth are the plants that surround us, and not the panels we manufacture. With billions of years of evolution to improve the formula, plants have a near perfect energy conversion efficiency, while our solutions struggle to achieve 20% efficiency. This is why many researchers are working to mimic plants for power generation, but those at the University of Georgia decided to just tap into plants and capture some of the electricity they produce.
Photosynthesis is the process plants use to take the energy of sunlight and with it create the sugars that fuel other processes throughout the organism. One of the steps involved separates the hydrogen and oxygen atoms in water, which releases electrons that then carry the energy to synthesize the sugars. Structures within the plant cells called thylakoids capture and store the energy from sunlight, and it is these that the researchers have modified to draw energy from. Instead of the electrons flowing as they normally would through the plant, they instead are directed down carbon nanotubes that have been connected to the thylakoids.
When tested, the researchers' design generated one hundred times more energy than similar systems, but as impressive as that is, there is still a lot of work to do. The technology and possibly the plants will need to be optimized before we could see literal 'power plants,' but some low power devices, like remote sensors, may be able to benefit from this research sooner.
Source: University of Georgia
Posted: May 10, 2013 09:04AM
A fun physics fact is that it is very likely than any image you have been shown of an atom is wrong. The reason these incorrect images are still being used is because they are effective teaching tools when discussing the placement of electrons within an atom. New experiments done by researchers at the University of Michigan and led by researchers at the University of Liverpool however have found that the structure of some atomic nuclei is more complicated than previously thought, but this is actually a good thing.
When asked to imagine the nucleus of an atom, many of you will likely picture a single sphere or a number of spheres pressed together, representing protons and neutrons. The physics that describe nuclei however, tell us that many atoms have elliptical nuclei, not spherical, and that some have a very unusual pear shape, which the researchers have now observed. By smashing beams of radon and radium isotopes into metal foils at CERN, the researchers were able to demonstrate that the nuclei of these atoms have an asymmetrical pear shape, or vibrate around it, which may have implications beyond nuclear physics.
After the Big Bang, an asymmetry in Nature emerged as particles of matter dominated those of antimatter, and physicists have been trying to discover why for decades. One possible explanation could be found by examining the asymmetry of these nuclei, as it may relate to a fifth fundamental force of Nature, which has not been observed before.
Posted: May 9, 2013 02:27PM
For a long time people were trying to understand how a gecko is able to crawl up surfaces too smooth to attach to with other, better known methods. Eventually it was discovered that gecko toes have extremely small hairs that take advantage of van der Waals forces to adhere to any surface. What helps the gecko though does not help carbon nanotubes, but Rice University researchers have found a solution to that.
Van der Waals forces exist between molecules that are sufficiently near each other for their electrostatic fields to interact, often causing them to attract. For a gecko, this attraction allows them to crawl up walls, but for carbon nanotubes, it causes them to clump together into an unusable mess. Previous research had successfully infused nanotubes with potassium atoms and then removed some with a solvent, to give the nanotubes a negative charge that counters the van der Waals forces. By adding cage-like crown ethers to the mix, the Rice researchers were able to remove additional potassium ions, thereby leaving behind more electrons to negatively charge the nanotubes.
This greater negative charge is enough to prevent the nanotubes from clumping together due to van der Waals forces, allowing more to be in a solution together. With more nanotubes in a solution, super strong and conductive fibers of nanotubes can be more easily created. Also, the negative charge applied to the nanotubes is more easily worked with than the positive charge a superacid would impart.
Source: Rice University
Posted: May 9, 2013 07:16AM
Materials are magnetic when the electrons within them are aligned in a common direction, as each electron has its own magnetic field, and these add up to the larger field of the material. Electrons do not need to line up like that though for the material to have special magnetic properties. For the first time, researchers at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) have observed a new magnetic alignment that may have interesting applications for transmitting information wirelessly.
Magnetic vortices are created when a material's electrons align in a circular path, like mini bar magnets placed end-to-end in a circle, with those in the middle pointing straight up or down. If you connect this to a DC power source, the vertical electrons will start rotating in a circle and emitting electromagnetic waves. If the speed of the DC signal is too high, those electrons will flip upside down, which impairs the ability to use them to transmit data. What the HZDR researchers found was a way to create three-dimensional vortices, which should not have this problem, at least not until higher speeds, because the electrons near the core are nearly vertical and reinforce those at the center. This prevents the flipping.
The material the researchers created is comprised of two magnetic disks, roughly 10 nm thick and 500 nm wide, with a nonmagnetic disk separating them. Potentially this tiny device could be made into an antenna capable of transmitting in the gigahertz range, where Wi-Fi networks currently operate.
Posted: May 8, 2013 04:48PM
As captured by Moore's Law, the rate of technological developments follows an exponential growth pattern, with one advance leading to many. This means that one year's development is also faster than the previous, which may make it hard for some to keep up, at least in theory. Researchers at North Carolina State University decided to test if older programmers have a hard time keeping up with new technologies, compared to younger developers, and found that increasing years comes with increasing skills.
Using over 80,000 profiles of programmers at StackOverflow, the researchers assessed the knowledge of individual programmers by their rating. At StackOverflow, users are able to ask and answer questions, and they are also rated by the quality of their answers and questions. These ratings can be used to estimate a user's understanding of programming, without having to individually survey them. The researchers found that ratings consistently increased with a user's age until they were in their 40's. There was not enough information to determine anything past that age.
The researchers also considered the number of subjects the programmers were commenting on and found that those in their 30's and older were considerably more knowledgeable than those between 15 and 30. Even with newer technologies that are less than ten years old, the older programmers demonstrated equal or greater knowledge. Looks like there is something to be said for experience.
Source: North Carolina State University
Posted: May 8, 2013 09:13AM
At times it can be weird not having a Twitter account, because it means next to nothing to me if someone gets a new follower or loses one. I do recognize that this is important to many Twitter users though, as do others, such as the researchers at the Georgia Institute of Technology who performed a first-of-its-kind longitudinal study on what gets you more follows.
To perform this study the researchers examined half a million tweets over 15 months and identified 2800 positive and negative terms, in order to label whether a tweet's content is positive or negative. After crunching all of the numbers the researchers found that people do not like it when you talk about yourself and are more likely to follow you if you post information, like a news item. Tweets should also be about positive, happy things, like how to grow your social network, instead of unemployment, illness, and death. Also, as useful as hashtags can be to show your support for something, they can be a turn off when abused, causing less people to follow you.
With this research finally done, we may start to see technologists utilize it to create tools to help grow their audiences. If you are interested in following the latest news from us, you can check out the RSS Feed link at the top of the page, below the Featured Articles.
Source: Georgia Institute of Technology
Posted: May 7, 2013 12:30PM
One of the special characteristics that distinguishes humanity from many other animals is our bipedal, upright gait. Our method of locomotion has evolved over millions of years, as have those methods other animals use, and many of these are now being studied very carefully for use in robots. Researchers at Cornell University however decided to approach walking a little differently by applying evolutionary algorithms on virtual robots to develop their gait or gallop.
Evolutionary algorithms work by mimicking natural evolution with mutations being introduced and the most successful systems being allowed to reproduce. In this case, being the most successful meant being the fastest. After 1000 generations, the robots proved to be unique looking with an interesting variety of mechanical solutions. Possibly with more generations the designs will be more similar to what we can find around us, as Nature has had the benefit of many times more generations.
The paper by the researchers concerning these robots can be freely downloaded: Unshackling Evolution: Evolving Soft Robots With Multiple Materials and a Powerful Generative Encoding (PDF).
Posted: May 7, 2013 08:59AM
Invisibility has been a special power in numerous stories from multiple cultures over uncountable years, but only recently has technology caught up to fantasy and brought it within reach. Since the first microwave cloak was created at Duke University, researchers have been working to design cloaks that operate in visible light and that use different materials and methods of cloaking. Now Duke Researchers have returned to creating a microwave invisibility cloak that has the unique property of having been printed by a 3D printer.
Three dimensional printers are special devices that are able to construct objects out of polymers, layer by layer, following instructions from a computer. Potentially these devices could be made cheap enough to enter households and there produce all manner of objects, including invisibility cloaks. When the researchers printed theirs it took from three to seven hours to create the device with special holes meant to deflect microwave beams. Advanced algorithms are used to determine where these holes are to be placed, along with their size and shape in order to affect the microwaves as desired.
Though the current cloak design is relatively small, the researchers believe larger versions could be created. They are also confident that visible-light cloaks could one day be printed.
Source: Duke Engineering
Posted: May 6, 2013 04:28PM
One of the hot topics in medical science today is the use of pluripotent stem cells to repair tissue damage that is otherwise untreatable. That however is something of a silver lining, and there is definitely a cloud that goes with it, such as the risk of stem cells developing into unintended cell types or even becoming cancerous. Researchers at the University of Wisconsin, Madison however have successfully convert adult, skin stem cells into neural progenitors, skipping the pluripotent stem cell stage, and thus the risks associated with it.
After harvesting the skin cells, the researchers treated them with a modified form of the Sendai virus, a type of cold virus. This virus has not been used for this purpose before, but does offer some advantages over those that are used, such as not entering the cell's DNA and it can be killed by heat within a day. Once the cells had their genes changed so they could become neural progenitors, the researchers heated the sample enough to kill the virus and waited thirteen days before harvesting the progenitor cells. These cells actually are a kind of stem cell but are not pluripotent, as they are only able to develop into any of the three major types of neural cells. After implantation into newborn mice, the cells grew normally and showed no sign of defects or tumors.
Currently this research is just proof-of-concept with more work to do, but it is certainly promising work. Potentially we could see neural progenitors created from the skin of ALS patients and other diseases to treat if not cure them.
Source: University of Wisconsin, Madison
Posted: May 6, 2013 09:08AM
The technology of the future may be quite different from what we are use to today, with the ongoing development of many materials with new and special properties. Among them are nanowires which can have their electrical characteristics determined by controlling what they are made of and their design. Researchers at the University of Illinois, Urbana-Champaign have recently discovered the spontaneous growth of nanowires with differing cores and outer shells.
There are a few ways to grow nanowires and all of them require a substrate for the wires to grow off of. Typically silicon is used for this, but the researchers decided to use graphene, a single-atom thick sheet of carbon, because it is cheaper, flexible, and less of it is needed. Graphene has been used as a substrate for growing nanowires previously, but this experiment differed from those as the nanowires were to be made of indium gallium arsenide (InGaAs); three elements instead of just two. To the researchers' surprise, the elements did not form solid InGaAs nanowires but an InAs core with an InGaAs shell surrounding it. This structure is desired for different applications and usually takes multiple steps, but here it was achieved in one.
Though the researchers did not expect this result, upon further examination they realized what happened. The distance between atoms in a crystal of InAs is roughly the same as a distance within graphene, so the InAs molecules fell into place, while the InGaAs molecules surrounded them.
Posted: May 3, 2013 03:00PM
Scientists at Havard University have built the smallest robot capable of flying, named the 'robo-fly'. The device weighs less than a gram, and employs insect-like 'wings' to fly, instead of conventional rotors or propellors. The construction is mainly carbon fiber, and uses piezoelectric material contracting around 120 times a second to power the 'wings'.
The robot's designers suggest that the robot may eventually have applications in rescue operations, for example locating surviors in cramped spaces, although it was not initially designed for this purpose. At the current stage of development, the robo-fly requires an external power source, however scientists are working on incorporating a small internal power source instead of using the external supply.
Source: BBC News
Posted: May 3, 2013 09:18AM
They say opposites attract, and electromagnetically, this is true, but what about gravitationally? For many years, researchers have been wondering if antimatter, the electromagnetic opposite of normal matter, falls up or down in a gravitational field. Now researchers at Berkeley Lab are examining their data for 434 anti-hydrogen atoms to answers the question.
Antimatter is a source of many questions concerning the entire Universe as theoretically the Big Bang that produced all normal matter should have produced equal parts antimatter. Obviously this is not the case because normal matter remains today. Since realizing this inconsistency, researchers have been trying to find all the differences between antimatter and normal matter, including the direction the particles move in a gravitational field. Watching atoms fall is not easy though, but the Berkeley Lab researchers realized they could use the magnetic traps holding the anti-atoms to make some measurements. Within a magnetic trap, magnetic fields will counteract gravity and hold the particles up, but once the fields are switched off, they will be free to move, and they can be detected when they strike the walls of the trap.
While this approach is very promising, the data was not very revealing. All it really demonstrated was that this approach could work, but the equipment and experiment needs some upgrades before the uncertainty is small enough to know for certain.
Source: Berkeley Lab
Posted: May 2, 2013 07:24PM
For decades science fiction has told us that the future will be filled with touch-based interfaces, and while in some cases that is true today, it is still limited to specialized devices. For that fantastic vision to be realized, projector, sensor, and computing technologies will have to be combined and intelligently designed to respond to a variety of inputs. Researchers at Carnegie Mellon University have brought that combination a little closer with the creation of WorldKit; a system to generate interfaces on the fly.
To create a smart room essentially requires a projector and a depth sensor, such as the Microsoft Kinect. WorldKit is the software to use with this hardware in order to interact with them and other devices. Instead of requiring an interface to have been created beforehand, WorldKit allows a user to paint an area they wish to use as a controller, and select what it controls from a menu. Using the data from the depth sensor, the software is also able to compensate for the curvature of objects in the room and warp the projections so they appear flat on a surface. This also allows the system to work with a standard coordinate system.
Next the researchers want to improve WorldKit to allow users to interact with interfaces floating in free-space, instead of just on the surfaces of objects. They see many applications for this technology, especially as devices become so advanced that we may see interactive light bulbs, that combine all of the hardware into a single unit.
Source: Carnegie Mellon University
Posted: May 2, 2013 09:05AM
Leadership can be an interesting topic of study, as one tries to discover the intricacies that make someone a good leader and the reason a leadership structure is needed in the first place. When it comes to survival, it makes sense that the most experienced and skilled persons would direct those less capable than they, but what about in games? That is the question researchers at Penn State sought to answer by analyzing 54,000 posts by 2500 players of an augmented reality game.
Leading up to the release of Halo 2, Microsoft created the I Love Bees game that had players decoding messages that sent them to payphones, for additional information. Naturally players communicated with each other to work together and discover the clues, and even though there was no formal leadership structure to the game, the players developed their own. Pouring over the posts at various websites and forums, the researchers made the interesting discovery that these generated leadership structures actually mimicked military leadership structures in both design and even designation. One group actually established generals to handle strategies, lieutenants to deal with specific tactics, and privates to follow orders, but none of the players were assigned their rank; they naturally selected their own.
Despite the similarities to the US military leadership structure, the researchers point out that very few of the players had any military experience to draw from. The leadership structures the players employed just spontaneously emerged from their desire to play the game most effectively.
Source: Penn State
Posted: May 1, 2013 03:02PM
Carbon nanotubes are funny little things as they come in so many forms with so many different properties. For example, some are great conductors of electricity while others are semiconductors, and all of this is determined by their structure. One critical characteristic of a nanotube's structure is its chirality and finally researchers at Aalto University, A.M. Prokhorov General Physics Institute RAS, and the Center for Electron Nanoscopy of Technical University have found a way to grow nanotubes with preferred chirality.
A simple example of chirality is handedness, as some objects twist in the right-handed direction or in the opposite, left-handed direction. Carbon nanotubes are more complicated though and require two chiral indices to be described. The researchers discovered that by reducing a solid solution in carbon monoxide they were able to form special cobalt nanoparticles to serve as a catalyst. From these catalysts the researchers were able to grow nanotubes with a 90% preference to being semiconducting and a 53% preference to having the chiral indices (6, 5), at 500 ºC. After dropping the temperature to 400 ºC, the researchers found the preferred chiral indices shifted to (7, 6) and (9, 4).
That is a lot of numbers relating to a complex topic, but what it boils down to is that the researchers have achieved something that could lead to a better understanding of how nanotubes grow. From there nanotubes with specific properties could be more easily produced, and thus used in devices and technologies.
Source: Aalto University
Posted: May 1, 2013 09:05AM
Let it never be said that scientists do not need to have some fun every now and then. A group of nanophysicists at IBM have created the world's smallest movie as the actors in it are made from carbon monoxide molecules.
To create the stop-motion film, the researchers turned to their scanning tunneling electron microscope, which moves a needle across the surface of its subject. By moving the needle in, closer than needed for collecting data, the researchers were able to use the attraction between it and the carbon monoxide to reposition the molecules for each frame.
This work has come after IBM researchers achieved the smallest magnetic bit consisting of just 12 atoms, which represents a dramatic increase in potential data storage density.
Posted: April 30, 2013 02:17PM
A primary reason why CDs, DVDs, and Blu-Ray disks contain different amounts of data is that they use different frequencies of light to encode the information. Higher frequency light has shorter wavelengths, which means less space is required for a single bit, such as the 405 nm wavelength of Blu-Ray technology. Researchers have been trying for some time to use zinc oxide to create ultraviolet lasers, and now those at North Carolina State University have succeeded.
Within lasers and LEDs are p-n junctions, where n-type and p-type materials meet. Negatively charged electrons from the n-type material enter the p-type material and there fall into positively charged holes. Provided the holes are at a lower energy level than the electrons, a photon will be released, representing the difference. The trouble with zinc oxide has been that the p-type material was unstable, but the researchers addressed that by introducing defect complexes, where a zinc atom is missing and the associated oxygen atom is replaced with nitrogen and hydrogen atoms.
The reason why so many researchers had been working with zinc oxide to use in UV lasers and LEDs is that it can be made with relatively few undesired defects, allowing it to be quite energy efficient. Fortunately what the researchers discovered does not disrupt that, and also fortunately, it can operate at room temperature.
Source: North Carolina State University
Posted: April 30, 2013 08:48AM
For years researchers have been working on technologies to replace modern computer memory for greater speed and efficiency. One of these technologies is resistive memory, or ReRAM, which stores data as changes in electrical resistance, like how memristors store information. Researchers at Jülich Aachen Research Alliance however have discovered that the theories behind memristors cannot be applied to ReRAM, and such a discovery could greatly help ReRAM evolve.
Both memristors and ReRAM are able to store information by changing their internal electrical resistance, but memristors are, by definition, passive devices. What the researchers discovered is that ReRAM cannot be considered passive because it actually operates like a mini-battery. Batteries store energy by moving ions between electrodes, and within ReRAM, ions move from one electrode to another, thereby changing the resistance of the cell.
This discovery will have many implications on future research in resistive memory as now there is a better understanding of how they operate. Also this discovery could lead to some rather interesting uses of ReRAM, by tapping into its battery qualities.
Source: Jülich Aachen Research Alliance
Posted: April 29, 2013 02:34PM
Touchscreens are becoming a near ubiquitous technology with smartphones, tablets, laptops and more employing them. Indeed it can be hard to imagine what our devices would be like if touch-sensitive screens were never developed. Now researchers at the Georgia Institute of Technology are working on a next generation of touch screens with much greater resolution and sensitivity.
At the heart of this new technology are touch-sensitive transistors called taxels that are made of zinc oxide nanowires. These wires exhibit the piezoelectric effect, which is a linking between electricity and mechanical force. When pressure is applied to a piezoelectric material, an electrical voltage is produced, thereby registering touch. These nanowires however are special because they are also semiconductors, so as pressure is applied to them, their resistance changes. This allows the researchers to achieve much higher sensitivity, comparable to that of human skin, and at a resolution approaching 100 micrometers.
There is still a fair amount of work to do before taxels could enter our devices, including finding a way to produce them from single nanowires instead of bundles and integrating them into CMOS silicon devices. Fortunately the touch-sensitive transistors are already transparent, which is important if they would be placed on our displays.
Source: Georgia Institute of Technology
Posted: April 29, 2013 09:47AM
The most powerful computational machine man has access to is not some supercomputer in a laboratory, but the human brain. The reason the organ is superior is that its billions of neurons have the ability to operate in parallel, unlike supercomputers which largely operate sequentially. This makes it so difficult for a supercomputer to simulate the human brain that what would take a brain a second to do, the computer requires hours to complete. As reported by NSF though, researchers have developed a news system with the ability to simulate the brain in real-time, while being far less power-hungry than a supercomputer.
Called Neurogrid, the system is made up of only 16 chips with 65,000 simulated, silicon neurons each, and each neuron is networked to thousands of others. While this does emulate the structure of the brain, what really gives Neurogrids its simulation superiority is how the neurons behave. Within the brain, neurons send signals to each other in a binary way, like computers, but within each neuron signals are processed non-linearly. Essentially neurons communicate digitally but think in analog, and supercomputers have a hard time compensating for this, but Neurogrid's neurons have been designed to operate similarly.
Along with being significantly faster than a supercomputer, Neurogrid is also much more efficient at mimicking the brain. While a supercomputer like Sequoia at Lawrence Livermore National Laboratory can require 8 megawatts of electricity to run, Neurogrid can operate with just 5 watts, making it much more accessible for future research into the brain.
Source: National Science Foundation
Posted: April 26, 2013 01:07PM
Though star formation may seem common based on what we see in the night sky, the process is somewhat delicate with winds and radiation from older stars able to prevent new stars from forming. This puts a limit on the efficiency with which a galaxy can form new stars, and now researchers have found a churning out stars at almost that limit.
The galaxy, SDSSJ1506+54, came to the researchers attention when NASA's Wide-field Infrared Survey Explorer (WISE) recorded massive amounts of infrared light being emanated from it. The researchers then brought in the IRAM Plateau de Bure interferometer which is able to detect carbon monoxide, an indicator of hydrogen gas. Combining the data from the two observatories revealed that the galaxy must be forming new stars almost at the Eddington Limit, the theoretical maximum for star formation. Any faster and formed stars would be disrupting the proto-stars made of hydrogen gas that would otherwise collapse into stars.
As impressive a sight as this is, it will likely be short lived as the galaxy is also blowing a great deal of gas away from itself. In just tens of millions of years, it will no longer be able to create new stars and start maturing into an elliptical galaxy, the final form of a galaxy as it cools off.
Source: McGill University
Posted: April 26, 2013 09:25AM
The Solar System existed long before man did, and will continue to exist long after humanity has died out, which can make it strange to consider times from before the Earth and Sun existed. With almost 10 billion years between the Big Bang and the formation of the Sun though, there is a lot of time there to consider, and every now and then we find something from that period. Researchers at Washington University in St. Louis have recently identified two grains of silica (SiO2) as not only being presolar, but from a supernova.
Presolar grains are definitely rare as they had to survive the heat of the early Solar System, but survive they did in the hearts of meteorites which later fell on Earth. To identify the grains as presolar, the researchers look at the oxygen isotopes. The materials that make up the Solar System all have roughly the same mix of isotopes, because everything got mixed together before settling into planets and the Sun. The researchers found these two grains were enriched in oxygen-18, unlike other presolar grains that have been discovered with enriched with oxygen-17. This difference the researchers believe is from the oxygen-17 grains coming from a red giant while the two oxygen-18 grains came from a supernova.
Supernova are among the brightest and most energetic events in the Universe, and it is believed that one triggered the formation of the Solar System. Potentially, these two grains are remnants of that very supernova, but only more study could possibly confirm that.
Posted: April 25, 2013 04:09PM
Over sixty years ago the first transistors were developed and were quite different from today's critical computing component in a number of ways. Perhaps the most obvious difference is that in the beginning they were the size of a thumbnail, while today they are measured in nanometers. Another difference though may be undone in the future, thanks to researchers at The Ohio State University.
The current dominate material in electronics is the semiconductor, silicon, but those first transistors were made from germanium, another semiconductor still used today, but is less common. That may change though as the researchers have isolated germanane, the germanium equivalent to graphene. Both graphene and germanane are single-atom thick sheets of their respective elements and conductor electrons at high speed, but germanane has the important property of being a semiconductor, unlike graphene. Researchers have been trying to create it for some time but the germanium atoms from one sheet kept binding to others, making multilayered crystals. To overcome this, the researchers forced calcium atoms between the layers before replacing them with hydrogen atoms. The bonds with the hydrogen atoms were so weak though that the layers of germanane could be successfully pulled apart.
While the electron mobility for germanane is definitely valuable, another property should also be. Unlike silicon and bulk germanium, germanane has a 'direct band gap,' which means it absorbs and emits light very easily; an important property for future optoelectronics.
Source: The Ohio State University