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.
October 11, 2012
It’s well established that, in the years to come, increasing amounts of carbon dioxide in the air will cause the climate to change, thereby leading to the ice caps melting at an accelerated rate and worldwide sea level rise. A new scientific finding, though, points at a troubling, entirely separate direct effect of carbon on ice—one that has nothing to do with warming at all.
As documented in a study published yesterday in the Journal of Physics D, researchers from MIT have discovered that merely being in the presence of increased concentrations of carbon dioxide causes ice to significantly weaken, with reduced material strength and fracture toughness, regardless of temperature. With enough carbon dioxide in the air, this alone could make glaciers more likely to split and fracture. Add in the fact that global temperatures will continue to warm—especially around the poles—and the combination of these two factors could mean that the ice caps will melt at even faster rates than experts have previously projected.
“If ice caps and glaciers were to continue to crack and break into pieces, their surface area that is exposed to air would be significantly increased, which could lead to accelerated melting and much reduced coverage area on the earth,” said the study’s lead author, Markus Buehler. “The consequences of these changes remain to be explored by the experts, but they might contribute to changes of the global climate.”
Buehler and his co-author, Zhao Qin, used computer simulations at the atomic level to evaluate the dynamics of ice strength in the presence of various concentrations of carbon dioxide. They found that the gas diminishes the strength of ice by interfering with the hydrogen bonds that hold together the water molecules in an ice crystal. Specifically, at the atomic level, the carbon dioxide competes with the bonded water molecules and, at high enough concentrations, displaces them from the bonds and takes their place.
The carbon dioxide molecules start infiltrating a piece of ice at an outer edge, then slowly split it apart by migrating inward as a crack forms. In doing so, they also attract water molecules outward to the edge by forming bonds with the water molecules’ hydrogen atoms, leaving broken bonds within the crystalline structure and decreasing the ice’s strength overall. The simulations showed that ice that has been infiltrated with carbon dioxide to the point that the gas occupies two percent of its volume is roughly 38 percent less strong.
“In some sense, the fracture of ice due to carbon dioxide is similar to the breakdown of materials due to corrosion, e.g., the structure of a car, building or power plant where chemical agents ‘gnaw’ at the materials, which slowly deteriorate,” Buehler told Environmental Research Web. Since glaciers typically begin to break apart with the formation of small cracks, the researchers say, this could lead to further large-scale fractures, such as the one that recently occurred in Antarctica and produced a fragment larger than New York City.
Because the finding is the first evidence of this phenomenon, it’s too early to say just how much it will accelerate ice melt beyond previous predictions. There are several mechanisms, though, by which it could lead experts to revise upward their estimates for ice melt and sea level rise given a continued increase in greenhouse gas emissions.
In addition to the obvious—that warmer air plus weaker ice means a faster rate of melting—there is the fact that the ice caps play a crucial role in reflecting sunlight back into space. Currently, they cover roughly seven percent of the earth’s surface but are responsible for reflecting 80 percent of the sun’s rays. This is because ice’s bright white color helps it reflect light more efficiently than nearly any other type of ground cover.
If increased carbon dioxide concentrations and warmer temperatures cause ice to melt unexpectedly quickly, though, this bright white ice will be replaced by dark ocean water. More and more sunlight would enter and stay in the atmosphere, thereby causing more and more warming. This positive feedback loop could constitute one of the dreaded “tipping points” that climatologists fear might send our climate on an uncontrolled path towards calamity.
Since the paper only deals with ice at the microscopic level, the next step would be testing the effect of increased carbon dioxide concentrations on ice in a lab setting to check if the effects of the simulated model hold true. Of course, if nothing changes in terms of carbon emissions, we might well have the chance to see if these effects occur on a much larger scale—in the world’s glaciers and polar ice caps.
August 27, 2012
How much do you think a molecule weighs? A molecule, which is single group of bonded atoms—the two hydrogens and one oxygen that make up H2O, for example—is almost incomprehensibly tiny. One mole of water, which is roughly 0.64 ounces, has 602,214,078,000,000,000,000,000 molecules. Molecules, in short, are really, really, really small.
Up until now, scientists could only calculate the mass of large groups of molecules, by ionizing them (giving them an electric charge) and then seeing how strongly they interacted with an electromagnetic field, a technique known as mass spectrometry. They had no way, however, of measuring the mass of a single molecule.
But yesterday scientists from Caltech announced the invention of a device that directly measures the mass of an individual molecule. As described in a paper published in the journal Nature Nanotechnology, the tiny apparatus is built around a bridge-like structure that vibrates at a specific frequency based on the mass of the molecule on top of it. By precisely tracking the vibrating frequency of the bridge, they can determine the exact mass of the molecule.
“The critical advance that we’ve made in this current work is that it now allows us to weigh molecules—one by one—as they come in,” says Michael Roukes, the principle investigator of the lab that produced the paper. “Nobody’s ever done this before.”
To the naked eye, the device is essentially invisible—the scale at the bottom of the microscope image above is two microns long, or two millionths of a meter. The vibrating bridge at its center is technically known as a nanoelectromechanical system resonator and has been under development for over a decade.
In previous work, published in 2009, the researchers showed that they could measure the mass of particles sprayed onto the apparatus but with one limitation: It wasn’t sensitive enough to measure just one molecule at a time. Because the specific location where a particle landed affected the vibrating frequency, and the scientists had no way of knowing exactly where this would be, they needed to apply several hundred identical particles in order to find an average, which revealed the mass.
The advance makes use of a new insight into the way the vibrating frequency of the bridge changes when a molecule is sprayed onto it. The vibrations occur in two modes simultaneously: The first mode is side-to-side swaying, while the second mode occurs in the form of an oscillating S-shaped wave that moves up and down the bridge. By analyzing exactly how each of these modes change when the molecule hits the device, the researchers found they could determine its position, and thus its exact mass.
In the study, the researchers demonstrated the effectiveness of the tool by measuring the mass of a molecule called immunoglobulin M, or IgM, an antibody produced by immune cells in the blood and that can exist in several different forms. By weighing each molecule, they were able to determine exactly which kind of IgM it was, hinting at potential future medical applications. A kind of cancer known as Waldenström macroglobulinemia, for instance, is reflected by a particular ratio of IgM molecules in a patient’s blood, so future instruments building on this principle could monitor blood to detect antibody imbalances indicative of cancer.
The scientists also envision this type of device as an aid to biological researchers looking into the molecular machinery inside a cell. Since the enzymes that drive a cell’s functioning are highly dependent on molecular attachments on their surface, precisely weighing proteins at various times and in different types of cells could help us better understand cellular processes.
The team even predicts that their invention could have everyday commercial applications. Environmental monitors that track nanoparticle pollution in the air, for instance, could be activated by arrays of these vibrating bridges.
Importantly, the scientists say, the device was constructed using standard semiconductor fabrication methods—the same used in common electrical circuits—so it can theoretically be scaled up to apparatuses that include hundreds or tens of thousands of the single-molecule sensors operating at once. “With the incorporation of the devices that are made by techniques for large-scale integration, we’re well on our way to creating such instruments,” says Roukes.
July 27, 2012
For the past 25 years, it seemed that we’d pretty much solved the ozone problem. In the 1970s and 80s, people around the world grew increasingly alarmed as research revealed that chemicals we were producing—such as CFCs, used in refrigeration— had started destroying the crucial ozone layer, high up in the atmopshere, that protects us from the sun’s harmful UV radiation. In response, world governments came together to sign the Montreal Protocol in 1987, which phased out the production of ozone-depleting chemicals. The concentration of these chemicals in the atmosphere leveled off within a decade.
Yesterday, though, Harvard scientists hit us with some bad news: It looks as if climate change could actually cause the depletion of the ozone layer to resume on a wide scale, with grim implications for the United States.
“If you were to ask me where this fits into the spectrum of things I worry about, right now it’s at the top of the list,” said professor James Anderson in a press release, discussing his team’s paper, published online in Science. “What this research does is connect, for the first time, climate change with ozone depletion, and ozone loss is directly tied to increases in skin cancer incidence, because more ultraviolet radiation is penetrating the atmosphere.”
The revelation comes from the researchers’ observation that warm-temperature summer storms can force moisture high up into the stratosphere, a layer of the atmosphere that sits about 6 miles above our heads. Typically, storm updrafts are halted at a boundary just below the stratosphere, but in a series of observation flights above the U.S., the team saw that storms with sufficient power injected water vapor into the stratosphere via convection currents.
Normally, the stratosphere is bone dry. In the Arctic and Antarctic, though, the presence of holes in the ozone layer is tied to moisture. Because water vapor raises the air temperature in the immediate vicinity, it allows compounds such as chlorine—leftover from CFCs, which will remain in our atmosphere for decades—to undergo a chemical shift into a free radical form, which then depletes ozone. In the warmer air above the U.S., the researchers measured that the local presence of water vapor increased the rate of ozone erosion as high as one hundredfold.
Because this mechanism has only been detected now, there are no historical data about how much water vapor has been moved upward by such storms over time, and so the researchers can’t say just how much total increased ozone depletion has occurred so far. But their concern is the future. The problem is that, as previous studies have shown, climate change is likely to mean more warm-temperature storms, especially over populated mid-latitude regions such as ours.
As a result, despite the best efforts of the Montral Protocol, the erosion of the ozone layer might accelerate in the coming century. The particularly troubling aspect of this discovery is that it puts highly-populated areas at risk, as compared to the polar regions previously observed.
“There has been a major effort by the medical community to define the relationship between decreases in ozone and the subsequent increases in skin cancer,” Anderson said. “The answer is quite clear–if you multiply the fractional decrease in ozone protection by about three, you get the increase in skin cancer incidence. There are 1 million new skin cancer cases in the U.S. annually–it’s the most common form of cancer, and it’s one that’s increasing in spite of all the medical research devoted to it.”
Much more field research is needed to track the rate of water vapor injections into the stratosphere, the attendant ozone depletion and the prevalence of skin cancer in the U.S. population. But as long as greenhouse gas emissions rise, the trend will likely continue. “We don’t know how rapidly the frequency and intensity of these storms will increase, so we can’t place a time scale on this problem, but the core issue here is quite straightforward and simple, because we understand this chemistry,” said Anderson
“In my mind, this is not just a broad public health issue,” Anderson added. “This is about actually being able to step out into the sunlight.”
June 11, 2012
One hundred years ago, in 1912, astronomer Vesto Slipher of the Lowell Observatory, in Flagstaff, Arizona, attempted to figure out the speed of Andromeda, the closest spiral galaxy to our own Milky Way. As he examined the shift in wavelengths that indicate Andromeda’s motion relative to us, he was surprised by what he found. Unlike nearly every other galaxy, which (we would soon learn) is moving away from us, indicating that the universe is expanding, Andromeda was doing something quite unusual: heading straight for us at a speed of 250,000 miles per hour.
Scientists were unsure what this would mean for our galaxy in the long-term. Would we collide directly with Andromeda, a galaxy roughly the same size as our Milky Way? Or would we slide past it, like two ships passing in the night? Now, as indicated in a paper published last week in the Astrophysical Journal, we know the Milky Way’s ultimate fate: a galactic collision.
“We’ve known for 100 years that Andromeda is getting closer to us, but to really know the trajectory it’s going to take, you need to know its sideways motion,” said Roeland van der Marel, an astronomer at the Space Telescope Science Institute and an author of the study. If Andromeda were moving enough on a sideways trajectory, it could have meant that it would fail to collide with the Milky Way, instead moving laterally past our galaxy.
“What we’ve done now is, for the first time, actually obtained a measurement for the sideways motion, using the Hubble space telescope,” he said, “and it turns out that the Andromeda galaxy is heading straight for us. Previously, this was a well-reasoned conjecture, and now it’s really a demonstrated fact.”
As shown in the NASA computer animation above, the Milky Way and Andromeda will be slowly drawn together due to their mutual gravitational pull, colliding roughly 4 billion years from now. Subsequently, the two galaxies will orbit around each other before merging in one big galactic pile-up. “On the first passage, they may either hit each other directly, smack on the face, or they may sort of just graze each other,” van der Marel said. “But either way, after that first passage, they get slowed down a lot, and that slowing down leads them to fall back together and merge as one.”
The resulting supergalaxy will be different from either of the current ones: Instead of the elegant, flat, spiral-shaped disc we know and love, the new galaxy will be a three-dimensional ball of stars.
The research team used images captured by the Hubble Space Telescope to determine the exact degree of sideways motion of Andromeda relative to our galaxy. ”To measure the sideways motion, you basically take an image, you wait a couple of years, and then you do it again and look if things have shifted,” van der Marel said. The researchers looked at images of three specific sections of Andromeda, taken either five or seven years apart, and used distant galaxies in the background—from our vantage point, behind Andromeda—as a stationary reference to compare them with.
“In the end, we found that there is a shift, and it was about one hundredth of a pixel on the cameras on Hubble,” he said. In other words, not enough to avert a collision in our distant future.
Astoundingly, this massive crash won’t have an enormous impact on earth, or the solar system as a whole. “Galaxies are mostly empty space, so there are lot of stars in them, but when the galaxies collide, individual stars don’t actually collide like billiard balls,” said van der Marel. “No star from Andromeda will actually directly hit our sun, and in fact, no star from Andromeda will even come close enough to the sun to perturb the orbit of the earth.” Instead, gravitational forces will fling the solar system as a whole outward within the new galaxy, so our night sky will change as we explore a different portion of the universe.
Regardless, the much bigger issue for life on earth is an unrelated long-term problem: the sun will gradually increase in temperature and then run out of nuclear fuel around the time the galaxies finish merging, 6 billion years from now, making the existence of life on this planet virtually impossible.
So, since this galactic collision isn’t something we need to fear, maybe we ought to welcome it. Perhaps we can begin by figuring out a name for our new supergalaxy. The Milkydromeda? The Andro Way? Clearly, suggestions are welcome. We’ve got roughly 4 billion years to figure something out.