Mother-of-pearl is surprisingly difficult to mimic. Cheap plastic watch faces don’t count—they may look like the inside of a seashell, but real mother-of-pearl, or nacre, to give its scientific name, is made of thousands of layers of calcium carbonate, with an intricate, interlocking crystal structure.
Because of that, it is phenomenally tough, and engineers would like to be able to use it as an industrial coating. Recently, a team of scientists devised a way to make microscopic layers of calcium carbonate accrete into a very similar crystal structure, mimicking the process that takes place in shellfish. You can see the result above: a sheet of material with the sheen and the strength of real mother-of-pearl.
Image courtesy of Nature Communications
Though the wing-flapping contraptions of early human flight haven’t quite caught on, researchers think birds may still have something to teach us about navigating the air: how to land. MIT researchers have made a system that can bring a modified glider to an elegant bird-like stop, causing it to set down on its tail.
Russ Tedrake of MIT’s Computer Science and Artificial Intelligence Laboratory and his student Rick Cory developed the computer model to bring a basic foam glider to a unique landing. The principle behind the plane’s stop is the same one used by stunt planes–stall. When its wings tilt back, the plane loses lift and falls from the sky. Traditional planes don’t use this method to land because the airflow is chaotic (see smoke visualization above) making it hard to predict how the plane will behave.
Birds come to a stop by tilting their wings back at sharp angles. This creates turbulence and large, unpredictable whirlwinds behind the wings. If an airplane pointed its wings up in this way, it would lose lift and fall out of the sky. But MIT researchers wanted to take advantage of stall–specifically, post-stall drag–to help a plane come to a controlled landing. [Popular Science]
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It’s not easy to find a material that’s both stretchy and hard. Neither is it to find a glue that will stick underwater. But this week researchers said that the solutions aquatic animals have created for those problems could inspire new materials in the lab.
Mussles have solved the hard-but-still-stretchy problem with their “beards.” The beards are actually made of 50 to 100 so-called byssal threads, and they are what anchor a mussel to a rock or other stable structure. According to study author Matthew Harrington, “they’re not only facing these huge wave forces which are trying to, you know, rip them off the rocks, but also they’re being blasted with debris like small pieces of sand and other debris in the water that are basically acting like sandblasting” [NPR]. If the mussels are blasted off the rocks, they’d likely be eaten or killed.
You’ve probably heard about the extraordinary strength of many kinds of spider silk, but researchers in China say they’ve figured out another fascinating property of the silk—how it catches water in the air—and created their own copycat material.
For a study in Nature, Chinese scientists looked at the small, non-poisonous cribellate spider’s silk. The secret, revealed by scanning electron microscope, lies in the silk’s tail-shaped protein fibres which change structure in response to water. Once in contact with humidity, tiny sections of the thread scrunge up into knots, whose randomly arranged nano-fibres provide a roughly, knobbly texture [AFP]. In between these knots are smooth areas where the fibers are neatly aligned, allowing water to slide along until it hits a knot, where dewdrops accumulate.
The next generation of bulletproof vests and military armor could well be inspired by a deep-sea snail, say scientists.
A team led by materials scientist Christine Ortiz of the Massachusetts Institute of Technology investigated the iron-rich shell of the “scaly foot” mollusk, whose triple-layered shell gives it one of the strongest exoskeletons seen in nature. The researchers believe that copying its microstructure could help in the development of armor for soldiers, tanks, and helicopters. Their work was published (pdf) this week in the Proceedings of the National Academy of Sciences.
Scientists were first drawn to this snail in 2003 when they discovered it living in a relatively harsh environment on the floor of the Indian Ocean. It lives near hydrothermal vents that spew hot water–thereby exposing it to fluctuations in temperature as well as high acidity. It also faces attacks from predators like crabs and other snail species. But unlike other snail species, this snail survives because of its thick shell and the different properties of each of its three layers.
A new discovery about how mantis shrimp process light could give rise to new and more powerful consumer electronics, according to a new study. Mantis shrimp possess the animal kingdom’s most complicated eyes, capable of distinguishing between 100,000 colors — 10 times as many as humans — and seeing circular polarized light, or CPL, which can’t be detected by any other creature [Wired.com]. Circular polarized light is one of two forms of polarized light, or light waves that travel in a specific plane.
The specialized CPL detecting cells in shrimp eye are similar to the optical detectors found in DVD players; each can convert polarized light into other forms so it can be stored or processed. However, shrimp eyes can do this with all colors of circular polarized light across the spectrum, according to the study in Nature Photonics. The detectors in DVD and CD players can only recognize circular polarized light in a few colors. The research team thinks that in the future, optics devices might be beefed up by chemically engineered crystals that could mimic the light polarizing cells of the mantis shrimp eye.
A humble marine worm may hold the key to mending bones that have been shattered: a strong adhesive that the worm uses to build its shell, and which hardens despite the worm’s watery habitat. Sandcastle worms, Phragmatopoma californica, dwell in the intertidal zone where they construct a tubelike shell by gluing together bits of sand, broken shells and other mineral debris. The glue is secreted from a special gland and hardens in less than 30 seconds underwater, forming a leatherlike consistency over several hours [Science News].
Medical engineer Russell Stewart has been working on a synthetic glue modeled on the worm’s adhesive. He thinks the worm-inspired glue could be just the thing for piecing together the small fragments of bone that result from complex breaks that must be glued within the wet environment of the body. “There’s lots of synthetic adhesives in widespread use for other things, [but] there’s no adhesives used for deep tissue repair,” Stewart said. Current remedies are primarily mechanical fixes, such as screws, pins, and plates, which can be an inefficient method for repairing highly fractured bones [The Scientist].
Researchers have learned the universal secret behind the graceful, aerial turns executed by everything from insects to cockatoos. And it’s a surprisingly simple process: To turn left, all a bird has to do is flap its right wing a little bit harder than the left wing. To end the turn, the bird simply returns to flapping its wings in unison [Discovery News]. Researchers hope to duplicate the simple set of motions to create more nimble and acrobatic flying robots.
Though the dynamics probably can’t work at large scales — building-sized robotic birds won’t ever be as agile as a swallow — they could be harnessed in small drones used by explorers or the military. Compared to the average hummingbird or fruit fly, such craft are now clumsy and unstable. “The results will inform all future research into maneuvering flight in animals and biomimetic flying robots” [Wired], wrote biomechanicist Bret Tobalske in a commentary.
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.
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.