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Nanomaterials

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Original author: 
John Timmer

FirasMT

In the past few years, there have been a regular series of announcements about devices that cloak something in space. These typically bend light around the cloak so that it comes out behind the object looking as if it had never shifted at all. In contrast, there's just been a single description of a temporal cloaking device, something that hides an event in time. The device works because in some media different frequencies of light move at different speeds. With the right combination of frequency shifts, it's possible to create and then re-seal a break in a light beam.

But that particular cloak could only create breaks in the light beam that lasted picoseconds. Basically, you couldn't hide all that much using it. Now, researchers have taken the same general approach and used it to hide signals in a beam of light sent through an optical fiber. When the cloak is in operation, the signals largely disappear. In this case the cloak can hide nearly half of the total bandwidth of the light, resulting in a hidden transmission rate of 12.7 Gigabits per second.

The work started with the Talbot effect in mind, in which a diffraction grating causes repeated images of the grating to appear at set distances away from it. The cloaking device relies on the converse of this. At other distances, the light intensity drops to zero. The key trick is to convert the Talbot effect from something that happens in space to something that happens in time.

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Original author: 
timothy

cylonlover writes "A team of scientists at Nanyang Technological University (NTU) in Singapore has developed a new image sensor from graphene that promises to improve the quality of images captured in low light conditions. In tests, it has proved to be 1,000 times more sensitive to light than existing complementary metal-oxide-semiconductor (CMOS) or charge-coupled device (CCD) camera sensors in addition to operating at much lower voltages, consequently using 10 times less energy."

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A flock of starlings is called a murmuration.

Walter Baxter

Scientists have built a self-organizing system of synthetic particles that assemble into clusters in a way that mimics the complicated organization of flocks of birds or colonies of bacteria. The particles form a “living crystal” that moves, swirls, and adjusts to heal cracks.

Self-assembly is a common way to build materials. Often, individual building blocks stick together due to inherent attractions, like bases of DNA bonding to form a nanotube, proteins gathering to form a helical virus coat, or nanospheres gathering to form a photonic crystal.

But what draws flocks of starlings, schools of fish, or rafts of ants together? Flocking or schooling can be a social behavior. However, the similarities among these phenomena, regardless of the creatures involved, led NYU's Jérémie Palacci and his colleagues to wonder if an underlying physical principle could also govern the organization process.

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Enlarge / Scanning electron micrograph of graphene, showing the hexagonal structure of the single layer of carbon atoms.

Lawrence Berkley National Laboratory

Graphene—a two-dimensional sheet of carbon one atom thick—is exciting stuff. Combining good electrical properties, flexibility, mechanical strength, and other advantages, graphene can seem like a miracle material, especially when potential applications are listed. Talk of graphene-based protective coatings, flexible transparent electronics, super powerful capacitors, and so forth may seem like something from a Neal Stephenson science fiction novel, but they've all been seriously considered.

The material's potential is so high that its discovery merited the 2010 Nobel Prize in physics, awarded to Andre Geim and Konstantin Novoselov. Certainly my fellow Ars Technica writers and I have spilled a lot of digital ink on the subject.

However, with so much excitement, you would be forgiven for wondering if at least some of it is hype. (After all, graphene has been around for a number of years, but we don't have our transparent computers yet.) For this reason, Nobel Laureate Konstantin Novoselov and colleagues have written a critical, yet optimistic, assessment of the state of graphene research and production.

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An anonymous reader writes "Graphene once again proves that it is quite possibly the most miraculous material known to man, this time by making saltwater drinkable. The process was developed by a group of MIT researchers who realized that graphene allowed for the creation of an incredibly precise sieve. Basically, the regular atomic structure of graphene means that you can create holes of any size, for example the size of a single molecule of water. Using this process scientist can desalinate saltwater 1,000 times faster than the Reverse Osmosis technique."


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Whether you live in a town, city, or countryside, noise is everywhere. Urban planners and civil engineers have been taking noise into account, and, modern apartments often have pretty good sound insulation. But, lets face it, in the middle of the night, noises do tend to creep through (and sometimes make you wish you were at the party in the neighboring apartment).

New materials that have the potential to create acoustically shielded environments may be on the way. In the latest development, researchers have shown how creating materials that have meandering paths for sound waves can result in a negative acoustic index of refraction. More importantly, these materials may actually be manufacturable and work for sound waves in air—the stuff we might consider noise.

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Researchers at Italy's Istituto Italiano di Tecnologia (IIT), home of the iCub, have created a way of giving extra properties to paper, including magnetism, waterproofing, fluorescence, and even the ability to clean itself and fight bacteria. However, despite these fundamental changes, it still looks and behaves like ordinary paper, and can be printed upon in the same way. The work centers around combining liquefied cellulose molecules (monomers) from wood or other plant material with the nanoparticles. These entirely coat the momomer fibers and create a polymer solution, which can be applied to any non-woven material like paper or fabric by rolling, dipping, or spray-coating.

The physical effect on the paper depends on the nanoparticles...

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