“LOOK MOM NO ELECTRICITY.” That was the first message conveyed by a rudimentary new communication system that researchers are calling the “infofuse.” In a new study, researchers printed patterns of three different flammable metallic salts on a nitrocellulose fuse and then set the fuse on fire. As it burned, it emitted pulses of different colored light that can be interpreted with a Morse code system.
In the study, published in the Proceedings of the National Academy of Sciences, researchers explain that they developed a code for the alphabet, numbers and four special characters (a full-stop, comma, exclamation mark and the “@” sign) based on the presence or absence of one of the three metals in each dot. Extra coding information comes from the length of the dot, which determines the duration with which it burns, and the space between dots, where no colour is produced [New Scientist]. They placed dots of the three metals–lithium, rubidium, and caesium–on the paper using an ordinary ink-jet printer. When the infofuse was set alight, its precise patterns were “read” by an optical detector.
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The up-and-coming electronics technology known as organic light-emitting diodes (OLEDs) has spent the week in the, yes, spotlight. Earlier this week researchers announced that they had joined OLEDs to a rubbery conductor to make a computer display screen that could be bent, folded, and crumpled. Now, another team has tweaked OLEDs to make ultra-efficient panels that produce a white light similar to that produced by traditional incandescent light bulbs. Study coauthor Karl Leo says some big technical hurdles still need to be overcome, but adds: “I’m pretty convinced that in a few years OLEDs will be a standard in buildings” [BBC News].
Incandescent lighting is being phased out in some parts of the world because it isn’t energy efficient, and it’s being replaced by compact fluorescent bulbs or light-emitting diode (LED) fixtures. But with both fluorescent and LED lighting, the quality of white light produced has always left something to be desired. Fluorescent lighting can make people appear unhealthy because less red light is emitted, while most white LEDs on the market today have a bluish quality, making them appear cold [Technology Review]. In contrast, OLEDs, which are made from organic compounds that emit light when electricity is passed through them, can provide a nice white light, but efficiency problems have held the technology back.
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Would you like to wear your Facebook profile on the sleeve of your T-shirt? Or maybe the artists Christo and Jeanne-Claude would like to wrap a building in computer screens? Such marvels may one day be possible due to a stretchy display researchers created by connecting organic light-emitting diodes to a new rubbery conductor. Researchers say the display is remarkably durable–they bent it, folded it in half, and even crumpled it up without affecting its performance. What’s more, the display, which is thinner and less power-hungry than equivalent plasma and LCD screens, is produced through a cheap industrial printing process [Fast Company].
Organic light-emitting diodes (OLEDs) are not yet familiar technology, but many researchers think they’ll play an important part in the next generation of electronics. The organic compounds in an OLED system emit light when an electric current is passed through them and need no backlight, which means they draw less power and can be thinner than a typical liquid crystal display (LCD) screen. But the real breakthrough in the current research is in the stretchy conductor underlying the OLEDs.
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Wouldn’t it be useful if an aging, weakening bridge started to turn red as a warning to structural engineers? That’s the potential inherent in a new invention from a team of chemists and materials scientists, who created a plastic that turns red when it’s exposed to stress. Ultimately, such color-changing polymers could be used as coatings on everything from bridges to airplane wings, alerting engineers when vital structures are near failure [ScienceNOW Daily News].
To make the red-alert plastics, researchers placed small ring-shaped molecules that they call “mechanophores” in the center of polymer chains. In response to mechanical force, these rings break, changing the color of the polymer [ScienceNOW Daily News].
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Two groups of researchers have found ways to “unzip” carbon nanotubes to make nanoribbons of graphene, and experts say the development could point the way towards a new generation of electronics, including computer chips that are faster and tinier than the silicon-based chips used today.
Graphene, an atom-thick sheet of honeycombed carbon, is one of the hottest materials around. It conducts electrons well, but is thin, transparent and strong, making it potentially useful in displays and solar panels. Ribbons of graphene could be more useful still. At widths of around 10 nanometres or less, electrons are forced to move lengthwise, and make the graphene behave as a semiconductor [Nature News].
However, the ribbons have proved extremely difficult to produce. Previously, nanoribbons of graphene [were] cut from larger sheets using chemical methods that, like a blunt pair of scissors, offer little control over the width of the ribbons [New Scientist].
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Lighter than air! Stronger than steel! More flexible than rubber! No, it’s not an upcoming superhero flick: It’s the latest marvelous formulation of carbon nanotubes–at least as reported by the creators of the new super-material. Researchers working on artificial muscles say they’ve created nanotech ribbons that make our human muscles look puny by comparison. The ribbons, which are made of long, entangled 11-nanometer-thick nanotubes, can stretch to more than three times their normal width but are stiffer and stronger than steel…. They can expand and contract thousands of times and withstand temperatures ranging from -190 to over 1,600 °C. What’s more, they are almost as light as air, and are transparent, conductive, and flexible [Technology Review].
The material is made from bundles of vertically aligned nanotubes that respond directly to electricity. Lengthwise, the muscle can expand and contract with tremendous speed; from side-to-side, it’s super-stiff. Its possibilities may only be limited by the imaginations of engineers. [The material's composition] “is akin to having diamond-like behavior in one direction, and rubber-like behavior in the others” [Wired], says material scientist John Madden, who wasn’t involved in the research.
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Fixing a scratch on your car could soon be as easy as parking it in a sunny driveway for an hour. Researchers have invented a self-healing coating that mends scratches when exposed to ultraviolet light, and say the material could keep everything from cars to iPods looking shiny and new.
The research team made the new coating by mixing chitosan—a derivative of chitin, the main component of arthropod exoskeletons—into polyurethane. They made tiny nicks in the new material, then exposed it to UV light about as intense as that given off by the sun. The radiation set off a series of reactions, causing damaged molecules to link up with each other again. The cuts healed in about 30 minutes [Wired].
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The joke about hydrogen-powered cars is that they’re about 10 years away–and always will be. The technology has been held up largely by the high cost of hydrogen fuel cells, but now researchers say they’ve found a way to bring down the cost dramatically by making a key component out of carbon nanotubes instead of platinum. More than half the cost of fuel-cell stacks comes from platinum, according to the Department of Energy. “Fuel cells haven’t been commercialized for larger-scale applications because platinum is too expensive,” says Liming Dai [Technology Review], the lead author of the new study.
Researcher found that tightly packed, vertically aligned carbon nanotubes doped with nitrogen were more effective as catalysts than platinum, which is usually used to help oxygen react within the fuel cell. That is a vital stage of the fuel cell cycle. Rather than burning fuel to create heat to power a turbine, fuel cells turn chemical energy directly into a flow of electricity. Hydrogen gas, for example, is pumped past one electrode (the anode), where it is split into its constituent electrons and protons. The electrons then flow out of the anode, providing electrical power, while the protons diffuse through the cell. Electrons and protons both end up at a second electrode (the cathode), where they combine with oxygen to form water [New Scientist].
That second reaction is very slow, so engineers have developed cathodes made out of materials that act as chemical catalysts and speed up the reaction. Until now, platinum was considered the best catalyst, but now carbon nanotubes with a trace of nitrogen (the critical ingredient) have left the precious metal in the dust.
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Researchers who created the first so-called invisibility cloak in 2006, have made significant advances that could lead to an invisibility cloak for visible light in as little as six months. “A large number of folks are looking at it, and I think it’s a matter of coupling the right material to the right device,” [Discovery News] said researcher David Smith. His team has developed an algorithm that speeds up the design of materials that can bend light around an object. Using the new algorithm, they were able to create an invisibility cloak that can bend much wider spectrum of microwaves than previous versions.
Invisibility cloaks rely on metamaterials, ones with unique properties that derive from [their] physical structure, not [their] chemical make up [Discovery News]. Smith compares the effect of metamaterials on light to mirages that appear over a road on sweltering days. “You see what looks like water hovering over the road, but it is in reality a reflection from the sky,” Smith said. “In that example, the mirage you see is cloaking the road below. In effect, we are creating an engineered mirage with this latest cloak design” [AFP].
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Thin, translucent sheets of graphene may one day allow electronic displays that can be folded and rolled up like a newspaper. Previously, the only way to make graphene—thin layers of carbon atoms that can conduct electricity at stunning speeds—was to use sticky tape to pull off thin films of graphite. Now researchers are developing a technique that can create flexible sheets of graphene on a commercially useful scale. “Until now, everyone has been using our so-called ‘pencil technique’ (the sticky-tape method) but the disadvantage is that the graphite crystals are quite small—it’s really painstaking research,” [BBC News] said Andre Geim, who was the first to create graphene in 2004.
It was Geim who first proposed that graphene could be made more efficiently using a method called chemical vapor deposition. On that advice, South Korean researchers found a way to deposit graphene using CVD, which involves evaporating a mixture of large carbon-containing molecules and firing it over a heated metal surface. The molecules break down, releasing carbon that re-organises on the surface in neat graphene sheets. The precise conditions of the experiment determine how many sheets are produced [BBC News]. The researchers used extremely thin pieces of nickel as the metal surface on which to grow the graphene, the molecules of which forms a regular hexagonal pattern similar to chicken wire. Afterward, the nickel can be chemically dissolved away, leaving behind pure graphene.
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By harnessing a quantum mechanic force of repulsion researchers have caused nanoparticles to repel each other, and in their next experiment they plan to levitate a tiny gold nanosphere. The quantum force is part of the Casimir effect, first predicted in 1948 by the Dutch physicist Hendrik Casimir, which describes both the attraction and repulsion that occur between two tiny objects held close together in a vacuum. While the attractive force has previously been demonstrated, the new experiment marks the first time the repulsive force has been seen in a lab.
But the experiment wasn’t just a neat physics trick; the researchers say the repulsive force may one day be used in nanoscale devices. Lead author Jeremy Munday says the research may lend itself to producing ultrasensitive detectors and almost friction-free devices by separating their components via Casimir repulsion. “Where you would normally have friction,” he says, “you can start to greatly reduce that by having a repulsive interaction that doesn’t let the surfaces come into contact” [Scientific American].
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A synthetic material that mimics the qualities of an iridescent opal may have wide-reaching technological applications, its creators say. With the application of an electric current the material can rapidly change to any color of the spectrum, and the developers, who said they’re ready to sell the technology today, added that their ‘photonic ink’ (P-Ink) material could soon be used in electronic books or advertising displays [ZDNet].
The synthetic material can be likened to an opal, a mineral that owes its variety of colours to its layered structure: regions with a high refractive index, in which light travels slowly, are interleaved with regions with a low refractive index. Light waves with a wavelength – or colour – similar to that of the space between layers are scattered in a way that gives opal its iridescent sheen [New Scientist]. The synthetic material has a similarly layered structure, but with the addition of a little voltage the space between the layers swells or shrinks, allowing for fine-tuned control of what color of light the material scatters.
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Federal research on the emerging field of nanotechnology has failed to adequately address health, safety, and environmental concerns, according to a critical new report from the National Research Council. With more than 600 products that use nanotech materials already on the market, the lag in research creates a risk to consumers, and could also fuel a “nanophobia” in which people assume that every product that uses the new technology is harmful. David Rejeski, director of the Project on Emerging Nanotechnologies … said the report echoed calls by industry and congressional leaders for a revamped research plan for nanotechnology. “The administration’s delay has hurt investor and consumer confidence,” Rejeski said in a statement. “It has gambled with public health and safety” [Reuters].
Nanomaterials are engineered on the scale of a billionth of a meter, perhaps 1/10,000 the width of a human hair. They are turning up in a range of items including consumer products like toothpaste and tennis rackets and industrial products like degreasers or adhesives [The New York Times]. Engineered nanoparticles can also be found in sunscreens, cosmetics, and the fabric used in “nano-pants” that resist stains.
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Researchers have created a strong, light-weight ceramic inspired by the composition of seashells, and say their new material could one day replace the aluminum alloys used in aerospace engineering. A seashell may seem like a fragile thing, but the iridescent mother-of-pearl coating on the inside of many shells has surprising toughness. Natural mother-of-pearl, also known as nacre, has a brick-and-mortar structure: Layers of “bricks” made from a calcium carbonate mineral are held together by thin films of a biopolymer “mortar” such as chitin [Chemical & Engineering News].
Researchers have tried to mimic this brick-and-mortar structure for years, but copying natural laminated materials has proved difficult, despite the best efforts of many researchers, says [lead researcher] Robert Ritchie…. Those best efforts have resulted in only very thin films, not bulk specimens with real-world practicality [New Scientist]. Now, researchers have come up with an ingenious way to produce a synthetic in large chunks, and say the material is both strong and resistant to fracture.
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Researchers have long known how to create surfaces that repel water (they just had to look at a duck’s back for an example), but how to repel oily liquids was a mystery until last year, when a team of MIT chemists created a material antisocial enough to repel liquids of both kinds. They have gone one better than nature, which is not known to have made materials with such properties. [Researchers] even had to coin a new word to describe their creation – “omniphobic” – literally meaning it hates everything [New Scientist].
Now, the same researchers have pushed the technology another step forward, by developing a set of general design rules for omniphobic materials and by altering existing items–like, for example, duck feathers–to make them repel both oil and water.
One of the biggest differences between water and an oily liquid such as octane, a component of petroleum, is surface tension. A droplet of a fluid with high surface tension — such as water — tends to pull itself into a sphere, whereas one with low surface tension, such as oil, tends to spread across a surface more readily [Science News]. Researchers first created a surface covered in 300-nanometer-tall “toadstools,” which allowed even oily liquids with low surface tension to remain in tight spherical droplets, essentially sitting on the toadstools’ caps.
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