April 1, 2013
Anyone who lives in or has visited a tropical country is likely familiar with the chipper chirping of the gecko. These friendly little lizards inhabit homes and jungles stretching from Indonesia to Tanzania to the Dominican Republic. They emerge after sunset, taking advantage of their night vision eyesight—which is 350 times more powerful than a human’s—and are welcome guests in homes and hotels since they gobble up mosquitoes and other insect pests.
In addition to the locals, scientists also love these colorful lizards. Geckos possess the unique ability among lizards to run up flat walls and scamper across ceilings, even if the surface is very smooth. Researchers have been puzzling over this ability for years, and dozens of labs have tested gecko adhesion in the hopes of harnessing this superpower for potential use in everything from robotics to space technology to medicine to “gecko tape.”
Gecko toes, it turns out, contain hair-like structures that form a multicontact interface, meaning geckos grip with thousands of tiny adhesive structures rather than what appears to be a single uniform foot.
Gaps remain, however, in researchers’ understanding of how gecko feet interact with surfaces in their natural environment, especially in dry versus wet conditions. Scientists know that gecko toe pads are superhydrophobic, or water repelling, yet geckos lose their ability to cling to glass when it becomes wet. Why don’t they just repel the water and cling to the glass surface below? Similarly, scientists wonder how geckos deal with wet leaves in the forest during rain storms.
A new paper published in Proceedings of the National Academy of Sciences investigates these mysteries. The authors decided to test gecko grip on a range of wet and dry materials that both attract and repel water. To perform their experiments, they outfitted six tokay geckos with gecko-sized harnesses. They placed the geckos onto four different types of materials, such as glass, plastic and a substance designed to mimic waxy tropical leaves. After giving the lizards some time to adjust to their new surroundings, the researchers applied a uniform tugging pressure onto the geckos’ harnesses, pulling in the opposite direction of where the animals were walking. Eventually, the geckos could cling no longer and lost their grip. This allowed the team to measure the adhesive force required to displace the animals. They repeated the same experiments under very wet conditions, too.
The authors found that materials that are more “wettable”—an indication of the degree to which a surface attracts water molecules—the less force it took to disrupt the clinging geckos’ grips. Glass had the highest wettability of the surfaces the researchers tested, and geckos easily slipped from wet glass compared to dry glass. When that material gets wet, water forms a thin, attractive film that prevents the gecko’s tiny toe hairs from coming into contact with the surface.
The low wettability properties of waxy leaves, on the other hand, allow geckos to establish a sturdy grip, even in rain storms, because leaves actively repel water. Geckos performed equally well in wet and dry conditions on the leaf-mimicking surface, the researchers found.
How the geckos interact with surfaces depends upon a thermodynamic theory of adhesion, the authors conclude. These features are dictated by Van der Waals force, or the sum of attractive and repulsive interactions between gecko toes and the characteristics of the surfaces they come into contact with. So long as those attractive forces jibe, geckos are in luck for getting a grip on whatever surface they come into contact with, regardless of whether it’s wet or dry.
Using our whole-animal adhesion results, we found that wet surfaces that are even weakly [water repulsive] allow the gecko adhesive system to remain functional for clinging and likely locomotion as well.
Our findings suggest a level of versatility in the gecko adhesive system that previously was not accounted for and calls into question interesting evolutionary, ecological, and behavioral predictions.
In addition to shedding light on how gecko adaptations help the lizards cope with their natural environment, the authors think their findings may contribute to designing new synthetic gecko robots that may overcome real-life geckos’ wet glass Achilles’ heel, useful perhaps for cleaning skyscraper windows, spying on suspected terrorists, or simply changing a hard-to-reach light bulb.
March 29, 2013
If the Easter Bunny comes to your house this weekend, you may find yourself with a plethora of marshmallows and Peeps. What to do with them all? Aside from simply eating them, cooking with them, or unleashing your artistic side by making dioramas, consider using them….for science!
Marshmallows, it turns out, are must-have pieces of equipment for at-home science experiments. Sure, you can use them test your kids’ self control through the the field of psychology’s notorious marshmallow test and its ever-more complex iterations. But if you’d rather not torture your kids by leaving tantalizingly in reach a marshmallow they’re ordered not to have, consider trying these easy science projects:
Marshmallows in a vacuum
No, not that kind of vacuum, despite the intriguing possibilities conjured by this phrase. You’ll need:
- A glass jar with a lid
- A mechanism to pump some of the air out of the jar
Place a few marshmallows in the jar, seal it, and then pump the air out:
What’s going on? Marshmallows are basically a foam spun out of sugar, water, air, and gelatin. The sugar makes them sweet, the water and sugar combo makes them sticky and the gelatin makes them stretchy. But the air–which actually makes up most of the confection’s volume–makes marshmallows the tastiest way to encapsulate a gas in a solid. As you pump air out of the jar, the air inside the marshmallow expands and the marshmallow puffs up. Release the seal, and the marshmallows return to their normal size.
Congratulations! You’ve just demonstrated Boyle’s Law, which states that when the temperature doesn’t change, that the relationship between pressure (which is decreased by pumping air out of the jar) and volume of any set amount of gas (the marshmallow) is inversely proportional. In other words, decreasing one necessitates an increase of the other.
If you can’t eat ‘em, nuke ‘em!
If you’ve ever roasted a marshmallow over a campfire, you’ll know where this next demonstration is going. You’ll need:
- A microwave
- A microwavable plate
- A standard-sized marshmallow (avoid minis or jumbos; the former will fry and the latter may make an enormous mess!)
Place the marshmallow on one of its flat sides in the center of a plate. Then microwave the marshmallow for, say, 45 seconds on high.
It’s alive! This time, rather than changing the pressure surrounding the marshmallow, you’re changing the temperature. As the microwave bakes the marshmallow, the water in the marshmallow heats up and warms the air. When air becomes hot, it expands, forcing the marshmallow to puff up. The confection’s water also softens the sugars, causing it to ooze, as seen in the video above (created by YouTube user bbbpwns).
The relationship between temperature and volume is representative of Charles’ Law, which holds that any set amount of gas will expand when heated–increasing the temperature of a gas necessitates an increase in the gas’ volume.
Trying this with Peeps makes for a slightly alarming outcome, showcased by YouTube user UBrocks:
If you flashed back to the Stay Puft Marshmallow Man, alas–the monster marshmallow you pulled from your microwave doesn’t last–it will cool and deflate into a glob of ooze. But before it cools completely, the ooze is quite malleable and can be sculpted into shapes. But careful! The marshmallow remnants are like naplam–they’ll stick to you and burn. After it cools a bit, brush some oil on your palms before you mold anything, else your sculpture will stay glued to your hands.
A gooey way to calculate the speed of light
For this demonstration you need a bit of background knowledge as you start out. The speed of a wave can be calculated by multiplying the wavelength (the distance from crest to crest) with the frequency (the number of crest-to-crest cycles that repeat in a stretch of time). Light is a wave, and its speed can be calculated the same way without fancy equipment. You’ll need:
- A microwave with the turntable removed
- A glass casserole dish or baking tray
- Mini marshmallows
- A ruler
- A calculator
Take the baking tray and pack one layer of marshmallows along the bottom, lined up like tiny puffy soldiers. Make sure the turntable is removed from the microwave–this allows microwaves to move through the glass and the marshmallows in a standing wave pattern. Cook for a few minutes on low, watching the marshmallows carefully. With the turntable removed, the microwave doesn’t heat evenly–you’ll notice melted patches forming in your marshmallow field.
As soon as you see a few such patches, remove the dish and measure the distance between two that form a line parallel to the microwave’s door–these mark the locations of highest amplitudes within the standing wave. Multiply this by two to get the full wavelength of the microwaves that passed through your marshmallows (if you look at the geometry of a standing wave, your initial measurement only gave you half the wavelength). Convert this into meters.
Multiplying this result by frequency of the microwave, found in the microwave’s manual or in a label inside the device, gives ~299,000,000 meters per second–roughly speed of light! Catch a video of this here.
December 28, 2012
Over the past year, we’ve seen a ton of scientific milestones and discoveries of historic importance, from the discovery of the Higgs Boson to the landing of a mobile laboratory on Mars. Science, though, is defined by its relentless march forward: No matter how much we learn, there are always more questions to answer. So, after our roundup of 2012′s most surprising (and significant) scientific events, we bring you the most exciting studies, projects and science developments we’ll be watching for in 2013.
1. Comet Ison: Back in September, a pair of Russian astronomers discovered a new comet heading in our direction. At the time, it was just a faint blip detectable only with the most sophisticated telescopes, and it was unclear how visible it would become during its approach. Now, though, astronomers are predicting that when it passes by us and closely orbits the sun in November and December of 2013, it could be the astronomical sight of our lifetimes. “Comet Ison could draw millions out into the dark to witness what could be the brightest comet seen in many generations—brighter even than the full Moon,” astronomer David Whitehouse writes in The Independent. One thing’s for sure: we’ll be watching.
2. Lake Vostok: For more than a decade, a team of Russian scientists has worked to drill nearly 12,000 feet down into Antarctica’s icy depths with a single purpose: to obtain samples from the ultra-deep isolated subglacial lake known as Lake Vostok. After barely reaching the water’s surface last Antarctic summer, they now plan to return at the end of 2013 to drill fully into the lake and use a robot to collect water and sediment samples. The lake may have been isolated for as long as 15 to 25 million years—providing the tantalizing potential for long-term isolated evolution that could yield utterly strange lifeforms. The lake could even serve as a model for the theoretical ice-covered oceans on Jupiter’s moon Europa, helping us better understand how evolution might occur elsewhere in the solar system.
Rival American and British teams were also racing to probe the depths of other subglacial lakes in search of life—the American team’s efforts to reach subglacial Lake Whillans is expected to meet with success this January or February, while the British have been forced to cease their drilling efforts into subglacial Lake Ellsworth due to technical difficulties.
3. Algae Fuel: Experts predict that 2013 will be the year when vehicle fuels derived from algae finally take off. A handful of biofuel stations in the San Francisco area started selling algae-based biodiesel commercially for the first time last month, and after the product met state fuel standards, the pilot program is expected to be expanded shortly. Because algae use less space, grow more quickly and can be more efficiently converted into oil than conventional crops used for biofuels, advocates are excited about the possibility that algae-based fuels could wean us off petroleum without using up precious food crops.
4. Cosmic Microwave Background: Energy left over from the Big Bang still radiates through the universe—and the European Space Agency’s plans to use the Planck satellite to measure this energy more precisely than ever before could help us better understand the formation of the universe. The 1965 measurement of this microwave energy first supported the concept of the Big Bang, and subsequent examination of variations in the radiation has led to more sophisticated theories about our universe’s earliest days. The Planck satellite, launched in 2009, has already collected a wide range of valuable astronomical data and images, but plans to release all this info in early 2013 has the cosmology world all atwitter.
5. Supercomputers to the Rescue: A number of supercomputers around the world could have a remarkable impact at solving problems in health, the environment and other fields over the next year. Yellowstone, a 1.5 petaflops cluster computer in Wyoming, was installed this past summer and will spend 2013 crunching numbers (1.5 quadrillion calculations per second, to be exact) to refine climate models and help us better understand how storms and wildfires move across the planet. Meanwhile, Watson, IBM’s world-famous Jeopardy-winning supercomputer, is currently being trained by doctors to recognize medical symptoms and serve as a diagnostic tool, providing treatment options based on case histories and clinical knowledge. So far, the computer has been trained to recognize breast, lung and prostate cancers.
December 14, 2012
The year 2012 was a major one for science. We saw scientists develop a new type of drug to combat HIV, figure out how to store digital data in DNA—fitting an astonishing 700 terabytes of information into a single gram of it—and even invent a coating for the inside of condiment bottles that could eliminate our stuck-ketchup-headaches once and for all (though, admittedly, this one is a little less groundbreaking than the others). Yet a few milestones in particular—discoveries, technological feats, realizations, and inventions—stand out:
1. The Higgs Boson: The landmark discovery by the European Organisation for Nuclear Research (CERN) of the once-mythical particle might be the most significant scientific discovery of our lifetimes, but it’s also one of the most surprising. Stephen Hawking, the Einstein of our time, famously bet Michigan physicist Gordon Kane $100 that it would never be found.
In an interview with The Atlantic, physicist Lawrence Krauss explained why so many experts had agreed with Hawking, arguing that the existence of the Higgs—a particle (and associated field) that makes certain types of elementary particles behave as though they had mass—was just too convenient, as it was originally posited simply to explain away an apparent difficulty in an otherwise appealing theory in theoretical physics.
The theory seeks to unite all physical forces under the same set of rules. But how can electromagnetic forces–governed by massless photons–fit under the same theoretical umbrella as the weak force, which is governed by bosons with discernible mass that control radioactive decay? Efforts to answer this conundrum gave birth to the Higgs boson. Krauss noted,”It seemed too easy…It seemed to me that introducing an invisible field to explain stuff is more like religion than science…Great, I invented invisible hobgoblins to make things right.”
Incredibly, in this case, it turned out the hobgoblins were real.
2. Earth-Like Planets: 2012 featured a ton of exoplanet discoveries, but the sighting of HD 40307g was without a doubt the most unexpected and exciting. The planet, bigger than earth but not so large as to be a gas giant, seems to orbit in its sun’s “goldilocks zone” (not too hot and not too cold), making it potentially capable of hosting liquid water, considered a prerequisite for life as we know it.
Even better, it’s just 42 light-years away: distant by human standards, but fairly close by compared many of the astronomical objects, making future projects to observe the planet much more feasible.
3. Curiosity Reaches Mars: Okay, the mission itself wasn’t too surprising—it’s been in the works since 2004—but what was so astonishing was the sudden surge of public interest in the rover and in space exploration as a whole. For decades following the manned Apollo missions of the 1960s and 70s, general enthusiasm for space science had slowly ebbed. After Curiosity’s successful landing, though, it surged. Among other things, video of NASA engineers celebrating the feat went viral and the official Curiosity twitter account garnered some 1.2 million followers.
People are so interested in Curiosity‘s exploits, in fact, that even an engineer’s throwaway line about “a discovery for the history books” pumped up expectations so much that we were bound to be disappointed by the actual finding: that early Martian soil samples seem to be representative of what we know of the planet as a whole, and that its chemistry is complex enough to have potentially once supported life. Bigger news might come over the next few years, but as project scientist John Grotzinger said, “Curiosity’s middle name is patience.”
4. Climate Change Is Even Worse Than We Thought: After decades of warnings from scientists that our greenhouse gas emissions will soon wreak havoc with the climate, we’re now starting to see the consequences—and they sure aren’t pretty. As a whole, experts are saying that the even the most frightening climate scenarios have proved to be too conservative in their analysis of how rising carbon dioxide concentrations will alter precipitation patterns, drive ocean acidification, lead to more powerful storms and, in general, make most parts of the planet grow warmer.
One silver lining might be that the public is now starting to acknowledge climate change as a present-day problem, rather than a hypothetical trend that could take effect in the future. Sadly, this has come only after record-breaking heat waves, droughts and the tragic impacts of Hurricane Sandy. Although the most recent international climate talks in Doha accomplished little, there are hopes that this shift in opinion could lead to a long-awaited change in policy sometime soon.
5. A New Way to Desalinate Seawater: With world populations expected to keep growing and potable water projected to grow more scarce over the coming century, a practical and cheap means of desalinating sea water is one of materials science’s holy grails. In July, MIT researchers announced the development of a new method of desalinization using one-atom-thick sheets of graphene, a pure carbon substance. Their method could be far cheaper and less energy-intensive than existing systems—potentially providing a way to solve many of the world’s water problems once and for all.
December 4, 2012
Chances are, sometime today, you sat in an office, classroom or workplace lit by constantly humming fluorescent light bulbs. Although they’ve long been favored by those who design buildings for their energy efficiency, fluorescent tubes are widely detested by those who sit in them because of the fact that they hum, flicker at a just-barely-perceptible rate, and emit an unsettling green tinge.
Now, while we search for replacements for the now-phased-out incandescent bulb, a group of researchers from Wake Forest University offers a potential solution. As they described yesterday in an article published in the journal Organic Electronics, they’ve harnessed a technology called field-induced polymer electroluminescence (FIPEL) to produce a constant, energy-efficient, soft white light.
“People often complain that fluorescent lights bother their eyes, and the hum from the fluorescent tubes irritates anyone sitting at a desk underneath them,” said David Carroll, one of the scientists leading the team. “The new lights we have created can cure both of those problems and more.”
The technology converts an electrical charge into light with three layers of a white-emitting plastic polymer matrix that incorporates trace amounts of nanomaterials that glow when stimulated. The team says the consistent white light that is produced has a similar spectrum to natural sunlight, so it’s also more pleasant to the human eye than the blue-tinged glow of LED lights. Researchers have been working to make FIPEL-based bulbs viable for some time, but this is the first instance of a practical use of the technology to produce light.
“[LEDs] have a bluish, harsh tint to them, ” Carroll told BBC News, “it is not really accommodating to the human eye; people complain of headaches and the reason is the spectral content of that light doesn’t match the Sun—our device can match the solar spectrum perfectly.”
His team also claims a number of other advantages for FIPEL. It’s more than twice as energy efficient as compact fluorescent (CFL) bulbs and roughly as efficient as LEDs. Unlike both of these bulbs, though, the bendable FIPEL technology is shatter-proof, so there’s no risk of contaminating a home or office with hazardous chemicals. It’s also extremely long-lasting: the researchers say a single FIPEL bulb may work effectively for up to a decade. Office workers will be especially excited to hear that it’s perfectly silent while in operation.
“What we’ve found is a way of creating light rather than heat,” he told BBC, explaining how his team’s devices achieve such a high level of energy efficiency. “Our devices contain no mercury, they contain no caustic chemicals and they don’t break as they are not made of glass.”
Additionally, the new technology can be manufactured in a variety of sizes and shapes. It could be incorporated into small bulbs with Edison sockets to fit light fixtures in homes, as well as large sheets to replace florescent tubes in offices. Although the team has focused on using it to make white light thus far, it can be altered to produce different colors, so it could eventually prove useful in large displays, such as public advertisements and storefronts.
The team says they’re currently partnering with a company to produce FIPEL-based bulbs on a broad scale and that the bulbs could be available to consumers sometime in 2013.