Brent Constantz builds cement like corals do
Biomineralization expert Brent Constantz of Stanford University was inspired to make a new type of cement for buildings by the way corals build reefs. The process of making this cement actually removes carbon dioxide – a greenhouse gas, thought to cause global warming – from the air. The company Constantz founded, called Calera, has a demonstration plant on California’s Monterrey Bay. The installation takes waste CO2 gas from a local power plant and dissolves it into seawater to form carbonate, which mixes with calcium in the seawater and creates a solid. It’s how corals form their skeletons, and how Constantz creates cement.
Ray Baughman creates artificial muscles
Nature has been developing her technologies for many hundreds of millions of years, said Ray Baughman. “By looking at the way in which nature has solved problems like muscles, we can advance our own technologies.” Baughman is director of the NanoTech Institute at the University of Texas at Dallas. His lab creates very tiny artificial muscles by spinning filaments of invisibly small carbon nanotubes into an extraordinary yarn. Pound for pound, this nano-yarn is stronger than steel – yet is so light it almost floats in air.
“The thorny devil, a tiny highly specialised lizard from the central Australian desert which lives entirely on ants has each scale enlarged and drawn out to a point in the centre. Few birds could relish such a thorny mouthful and to that extent, they must be a very effective defence, but the shape of the scales also serves another and most unusual function. Each is scored with very thin grooves radiating from the central peak. During cold nights, dew condenses on them and is drawn by capillary action along the grooves and eventually down to the tiny creature’s mouth.” (Attenborough 1979:164)
The Thorny Devil (Moloch horridus) can gather all the water it needs directly from rain, standing water, or from soil moisture, against gravity without using energy or a pumping device. Water is conveyed to this desert lizard’s mouth by capillary action through a circulatory system on the surface of its skin, comprised of semi-enclosed channels 5-150 µm wide running between cutaneous scales. Channel surfaces are heavily convoluted, greatly increasing the effective surface area to which water can hydrogen-bond and hence capillary action force. Passive collection and distribution systems of naturally distilled water could help provide clean water supplies to the 1 billion people estimated to lack this vital resource, reduce the energy consumption required in collecting and transporting water by pump action (e.g., to the tops of buildings), and provide a variety of other inexpensive technological solutions such as managing heat through evaporative cooling systems, protecting structures from fire through on-demand water barriers, etc.
A robot that flies like a bird
Plenty of robots can fly, but none can fly like a real bird. That is, until Markus Fischer and his team at Festo built SmartBird, a large, lightweight robot, modeled on a seagull, that flies by flapping its wings. A soaring demo fresh from TEDGlobal 2011.
This butterfly could hold the secret to letting you see in the dark
The opalescent wings of the Morpho butterfly embody a perfect marriage of aesthetic beauty and biological functionality. Scientists believe that a better understanding of this creature’s wings and their chemical makeup could have big implications for imaging technologies like night vision goggles that rely on sensing heat, rather than visible light.
Now, a team of GE researchers has taken an important step in accomplishing exactly that.
One of the biggest problems facing thermal imaging technologies is temperature management. The sensors in a heat-sensing device have to be cooled constantly, otherwise the image you see becomes washed out with old, and therefore insignificant, heat measurements. Imagine watching a person walk across a room while wearing thermal imaging goggles — if the thermal sensor’s temperature wasn’t kept in check, you’d be able to see a sort of thermal ghost trailing behind the person as they moved across your field of vision.
Physics World’s Tim Wogan explains the challenges of regulating the heat of thermal sensors:
The most sensitive thermal imagers require liquid-helium refrigeration. Since the heat sinks required are relatively large and power-hungry, this limits the minimum size and efficiency of the sensors. These requirements pose severe challenges for those designing portable equipment, such as thermal-imaging goggles. Indeed, goggles pose a particular problem because an ideal pair would be transparent to visible light, which is difficult to achieve with heat sinks in the way.
This is where the Morpho butterfly swoops in to save the day. The scales that cover the Morpho’s iridescent wings reflect light at some wavelengths, while absorbing it at others; these absorption/reflection properties can even change depending on the wings’ temperature, shifting the color of the wings in the process.
This is a pretty inspired biological feature, and it’s one that scientists believe could be put to use in thermal imaging sensors; but what researchers are really impressed with is the chitin that the scales of the Morpho wings are actually made of.
Chitin has a much lower heat capacity than the materials that are used in contemporary thermal sensors; lower heat capacity, in turn, eliminates the need for bulky, energy-hungry cooling methods. In the thermographic video featured here, you can see a Morpho butterfly responding quickly to heat pulses distributed first across the whole butterfly structure, and then onto localized regions of the wings.
And believe it or not, we can make these wings even more impressive — and with carbon nanotubes, no less! Writes Wogan:
Building on previous work by other researchers that revealed that decorating a material surface with carbon nanotubes enhances its ability to absorb infrared radiation, [a research team led by analytical chemist Radislav Potyrailo] showed that the [Morpho’s wings] absorbed infrared better if carbon nanotubes were added to the exposed surface. As a bonus, because carbon nanotubes have excellent thermal conductivity, the decoration helped to diffuse heat through the chitin away from the site of irradiation, thus providing a molecular heat sink.
In other words, Potyrailo and his colleagues showed that treating Morpho scales with carbon nanotubes not only enhances their ability to absorb radiation at wavelengths relevant to thermal imaging, it actually improves their ability to diffuse heat.
The question that remains is: how do researchers translate the functionality of nanotube-doped butterfly wings into a synthetic thermal sensor? Poryrailo and his team have already created an ersatz version of Morpho wings, but they still need a way to incorporate the chitin that grants them their unique heat-dissipating abilities. Once they do that, however, the researchers believe it could mark a major shift toward cheap, more effective thermal-imaging devices.
Better Body Armor? Piranha-Proof Fish Have Answers
The armor that a massive Amazonian fish evolved against piranhas could lead to better body armor for soldiers, researchers say.
The arapaima (Arapaima gigas) is one of the largest freshwater fish in the world, weighing up to 440 pounds (200 kilograms). It lives in the Amazon, and as the waters of the rivers there recede during the dry season, it gets trapped alongside piranhas, and the latter eventually attack every bird, fish, mammal and reptile they can, save alligators.
“I’ve gone to the Amazon many times — I first spent time there as part of a Peace Corps project when I was 20,” said researcher Marc Meyers, a material scientist at the University of California, San Diego. “I remember being struck by how the arapaima could live in these piranha-infested lakes.”
It turns out the arapaima can thrive in this crowded environment. As such, Meyers and his colleagues wanted to learn how it could coexist with such a ravenous predator, especially one with a guillotine-like bite highly effective at slicing through muscle.
The researchers devised a mechanical version of a fight between a piranha and an arapaima. Piranha teeth were attached to what was essentially an industrial-strength hole punch and pressed down onto arapaima scales up to 4 inches (10 centimeters) long, which were embedded on a soft rubber surface that mimicked the muscle of the fish. They found the cutting and puncturing ability of the piranha teeth could not penetrate the arapaima scales.
The arapaima experiments suggest a number of lessons when it comes to designing advanced materials. For instance, the corrugated, ridged surfaces of the scales, which people in the Amazon sometimes use as nail files, help the scales bend without cracking, a discovery that could be of use when working with brittle materials such as ceramics. In addition, the scales mix soft and hard materials — soft collagen fibers stacked in alternating directions like a pile of plywood lend toughness to the scale, and a very hefty mineralized layer on top lends hardness.
Such flexible, tough, hard materials could be useful in body armor, Meyers said. “I believe that this can be used for flexible armor,” he told InnovationNewsDaily. “I am in the process of contacting funding agencies for support.”
The researchers will continue exploring the natural world for inspiration, “asking, ‘how does nature put these things together?’” Meyers said. Another project will involve the alligator gar, a huge fish from the American South whose scales were used by Native Americans as arrow tips. The researchers are also studying abalone shells and leatherback turtle skin for inspiration.
“The materials that nature has at its disposal are not very strong, but nature combines them in a very ingenious way to produce strong components and strong designs,” Meyers said.
The researchers detailed their findings online Jan. 9 in the journal Advanced Engineering Materials. The work was also detailed in the October 2011 issue of the Journal of the Mechanical Behavior of Biomedical Materials.
Are zebra stripes just an elaborate insect repellent?
“How the zebra got his stripes” sounds like the title of one of Rudyard Kipling’s “Just So” stories. Sadly, it isn’t, so the question has, instead, been left to zoologists. But they, too, have let their imaginations rip. Some have suggested camouflage. (Charles Darwin pooh-poohed that idea, pointing out that zebra graze in the open, not amid thick vegetation where a striped pattern might break up their outlines.) Others suggest they are a way to display an individual’s fitness. Irregular stripes would let potential mates know that someone was not up to snuff. One researcher proposed that stripes are to zebra what faces are to people, allowing them to recognise each other, since every animal has a unique stripe-print. Another even speculated that predators might get dizzy watching a herd of stripes gallop by.
There is, however, one other idea: that stripes are a sophisticated form of fly repellent. It was originally dreamed up in the 1980s, but never proved. Now, a team of investigators led by Gabor Horvath of Eotvos University in Budapest report in the Journal of Experimental Biology that they think they have done so.
The original suggestion was that stripes repel tsetse flies. These insects carry sleeping sickness, which is as much a bane of ungulates as it is of people. But tsetses are not the only dipteran foes of zebra and, since they are rarely found in the meadows of Hungary, Dr Horvath plumped for studying an almost equally obnoxious alternative: the horsefly.
Horseflies, too, transmit disease. They also bite incessantly, thus keeping grazing beasts from their dinner. Indeed, previous research has shown that fly attacks on horses and cattle reduce their body fat and milk production. Such research has also shown something odd: horseflies attack black horses in preference to white ones. That fact got Dr Horvath wondering how they would react to a striped horse—in other words, a zebra.
Actual zebra are hard to experiment on. They insist on moving around and swishing their tails. The team therefore conducted their study using inanimate objects. Some were painted uniformly dark or uniformly light, and some had stripes of various widths. Some were plastic trays filled with salad oil (to trap any insect that landed). Some were glue-covered boards. And some were actual models of zebra. They put these objects in a field infested with horseflies and counted the number of insects they trapped.
Their first discovery was that stripes attracted fewer flies than solid, uniform colours. As intriguingly, though, they also found that the least attractive pattern of stripes was precisely those of the sort of width found on zebra hides. Zebra stripes do, therefore, seem to repel horseflies.
Exactly why is unclear. But Dr Horvath thinks it might be related to a horsefly’s ability to see polarised light, which imposes a sense of horizontal and vertical on an image. Horseflies are known to prefer horizontal polarised light. Possibly, the mostly vertical stripes on a zebra confuse the fly’s tiny brain and thus stop it seeing the animal.
Another obvious question, though, is why other species have not evolved this elegant form of fly repellent, and what the consequences would have been if they had. If humans, for example, were black-and-white striped then the history of intercommunal violence the species has suffered when different races have met might not have been quite as bad. One for Kipling to have pondered, perhaps?
Source: The Economist
Humpback whale secret may help helicopters fly faster
DLR Institute of Aerodynamics and Flow Technology / DLR Institute of Aeroelasticity
Helicopters can deliver military troops or rescue the wounded in tight spaces, but their rotating blade design also puts a hard limit on their speed and maneuverability. Now researchers have begun flight-testing an unlikely fix inspired by the underwater ballet of humpback whales.
The potentially cheap solution uses small bumps along the front edge of the helicopter blades similar to bumps found on the large pectoral fins of humpback whales. Such bumps give an aerodynamic edge that delays the moment of “stalling” when there’s not enough lift to keep the whale from sinking — or a helicopter from stalling out at top speeds.
“Stalling is one of the most serious problems in helicopter aerodynamics — and one of the most complex,” said Kai Richter from the DLR Institute of Aerodynamics and Flow Technology in Germany.
Helicopters face a speed limit because their backward-moving rotor blade goes against their forward motion of flight. That problem leads to turbulence and loss of lift, as well as strong forces acting on the rotor, which eventually cause the helicopter to stall out.
German researchers patented the bump idea for helicopters, under the name “Leading-Edge Vortex Generators.” Wind tunnel experiments led to a test flight with a helicopter carrying 186 rubber bumps —each less than a quarter of an inch long — glued to its four rotor blades.
“The pilots have already noticed a difference in the behavior of the rotor blades,” Richter said. “The next step is a flight using special measuring equipment to accurately record the effects.”
If testing goes well, existing helicopters could get a speed boost with simple retrofits. New helicopters could have the design built into their titanium blades during manufacturing.
The natural bump design already helps humpback whales swim at speeds of up to 16.5 miles per hour, or about five times faster than the fastest human swimmer.
“Research has shown that these bumps cause stalling to occur significantly later underwater and increase buoyancy,” said Holger Mai from the DLR Institute of Aeroelasticity in Germany. “Flow phenomena in water are similar to those in air; they just need to be scaled accordingly.”
Source: Innovation News Daily
Not a scratch
Scorpions may have lessons to teach aircraft designers
The north African desert scorpion, Androctonus australis, is a hardy creature. Most animals that live in deserts dig burrows to protect themselves from the sand-laden wind. Not Androctonus. It usually toughs things out at the surface. Yet when the sand whips by at speeds that would strip paint away from steel, the scorpion is able to scurry off without apparent damage. Han Zhiwu of Jilin University, in China, and his colleagues wondered why.
Their curiosity is not just academic. Aircraft engines and helicopter rotor-blades are constantly abraded by atmospheric dust, and a way of slowing down this abrasion would be welcome. Dr Han suspects that scorpions may provide an answer. As he writes in Langmuir, he has discovered that the surface of Androctonus’s exoskeleton is odd. And when that oddness is translated into other materials it seems to protect them, as well.
Dr Han’s investigations began by scouring the pet shops of Changchun, where the university is located, for scorpions. Having obtained his specimens, he photographed them under a microscope, using ultraviolet light. This made the animals’ exoskeletons, which are composed of a sugar-based polymer called chitin, fluoresce—thus revealing details of their surface features. The team found that Androctonus armour is covered with dome-shaped granules that are 10 microns high and between 25 and 80 microns across. These, they suspected, were the key to its insouciance in the face of sandstorms.
To check, they took further photographs. In particular, they used a laser scanning system to make a three-dimensional map of the armour and then plugged the result into a computer program that blasted the virtual armour with virtual sand grains at various angles of attack. This process revealed that the granules were disturbing the air flow near the skeleton’s surface in ways that appeared to be reducing the erosion rate. Their model suggested that if scorpion exoskeletons were smooth, they would experience almost twice the erosion rate that they actually do.
Having tried things out in a computer, the team then tried them for real. They placed samples of steel in a wind tunnel and fired grains of sand at them using compressed air. One piece of steel was smooth, but the others had grooves of different heights, widths and separations, inspired by scorpion exoskeleton, etched onto their surfaces. Each sample was exposed to the lab-generated sandstorm for five minutes and then weighed to find out how badly it had been eroded.
The upshot was that the pattern most resembling scorpion armour—with grooves that were 2mm apart, 5mm wide and 4mm high—proved best able to withstand the assault. Though not as good as the computer model suggested real scorpion geometry is, such grooving nevertheless cut erosion by a fifth, compared with a smooth steel surface. The lesson for aircraft makers, Dr Han suggests, is that a little surface irregularity might help to prolong the active lives of planes and helicopters, as well as those of scorpions.
Source: The Economist
Ghost Knifefish as Template for Underwater Robots
From omnidirectional on-land robots to underwater ones, the ghost knifefish’s ability to instantly switch from swimming forward and backward to going straight up, thanks a fin that recalls a ribbon on its underbelly is offering a template for ocean exploration. Currently, underwater robots are little more than submerged bathtubs, according to Malcolm MacIver, an engineer at Northwestern University. Using the ghost knifefish’s capabilities, MacIver and his team developed a bio-inspired robot, called GhostBot, with a similar appendage. They believe it could be used, among other tasks, for monitoring coral reefs or to plugging leaking underwater oil pipes.
Found on FastCompany