Astronomy
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Schiaparelli Is Gone. Smashed On The Surface Of Mars
Instead of a controlled descent to the surface using its thrusters, ESA’s Schiaparelli lander hit the ground hard and may very well have exploded on impact. NASA’s Mars Reconnaissance Orbiter then-and-now photos of the landing site have identified new markings on the surface of the Red Planet that are believed connected to the ill-fated lander.
Schiaparelli entered the martian atmosphere at 10:42 a.m. EDT (14:42 GMT) on October 19 and began a 6-minute descent to the surface, but contact was lost shortly before expected touchdown seconds after the parachute and back cover were discarded. One day later, the Mars Reconnaissance Orbiter took photos of the expected touchdown site as part of a planned imaging run.
One of the features is bright and can be associated with the 39-foot-wide (12-meter) diameter parachute used in the second stage of Schiaparelli’s descent. The parachute and the associated back shield were released from Schiaparelli prior to the final phase, during which its nine thrusters should have slowed it to a standstill just above the surface.
The other new feature is a fuzzy dark patch or crater roughly 50 x 130 feet (15 x 40 meters) across and about 0.6 miles (1 km) north of the parachute. It’s believed to be the impact crater created by the Schiaparelli module following a much longer free fall than planned after the thrusters were switched off prematurely.
Mission control estimates that Schiaparelli dropped from between 1.2 and 2.5 miles (2 and 4 km) altitude, striking the Martian surface at more than 186 miles an hour (300 km/h). The dark spot is either disturbed surface material or it could also be due to the lander exploding on impact, since its thruster propellant tanks were likely still full. ESA cautions that these findings are still preliminary.
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Clouds On Pluto? Dwarf Planet's Weather Gets Weirder
NASA's New Horizons spacecraft flew by Pluto in July 2015, revealing a bounty of unexpected details about the frozen world. For instance, the mission discovered that Pluto possesses a complex, layered atmosphere.
"We've noticed a large number of concentric layers of haze, more than two dozen," New Horizons principal investigator Alan Stern, of the Southwest Research Institute in Boulder, Colorado, said during a news conference here at the 2016 American Astronomical Society's Division of Planetary Science meeting. "These haze layers stretch very high into the sky — more than a half million feet, or 200 kilometers."
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All these potential clouds "are similar in that they are very low-altitude, and all are very similar in length scales, measured in kilometers or tens of kilometers," Stern said. "We're not seeing decks or banks of clouds — we're seeing individual, discrete cloud features," he said.
All seven of these features lie near the terminator, the dividing line between day and night, "either near dawn or dusk, which suggests they may be clouds, because there are cooler conditions there where condensation processes are likely to occur," Stern said.
Computer models of Pluto's atmosphere suggest that the most likely place to find clouds on Pluto are at low altitudes, where the seven features presented today are located. The models suggest that any such clouds are likely made of minor trace constituents of Pluto's atmosphere, such as acetylene, ethane and hydrogen cyanide, Stern said.
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Biology
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Jet Lag Treatment? Blast Of Thin Air Can Reset Circadian Clocks
Presently, light, food, and temperature are the best known cues that can influence circadian rhythms. But lead author Gad Asher, a senior scientist at the Weizmann Institute of Science in Rehovot, Israel, and his colleagues, including postdoctoral fellows Yaarit Adamovich and Benjamin Ladeuix, wondered if oxygen might also cue circadian rhythms since oxygen absorption in animals varies alongside meals and changing temperatures.
In the paper, the researchers show that changing the concentration of oxygen in cells by just 3%, twice a day, will synchronize mouse cells to a circadian rhythm. They suspected HIF1α was the link between oxygen and the circadian clock because HIF1α plays both a role in oxygen homeostasis in cells. They found that cells with low HIF1α levels won't synchronize in response to oxygen variations.
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The researchers further explored oxygen's effect on circadian rhythms with jetlag experiments. Just like humans, mice are prone to jetlag after a sudden shift in daylight hours. Mice were first left to eat, sleep and run on their wheels in air-controlled environments. Altering oxygen levels alone did not change their circadian rhythms but once mice experienced a 6-hour jump ahead in daylight hours, varying oxygen levels could help them adapt their eating, sleeping and running habits to the new time faster. They also saw that a small drop in oxygen levels 12 hours before the 6-hour daylight shift, or 2 hours afterwards, put the mice back on their circadian schedules faster and this too was dependent on HIF1α levels.
Presently, commercial airliners pressurize cabins to the same air density of a city 6,000-8,000 feet above sea level. This low-pressure saves wear and tear on the airplane, but enough passengers suffer from airsickness in response to this drop in oxygen levels that some airlines are considering ways to increase the pressure on flights. In fact, Boeing designed its new 787 Dreamliner so that it can be pressurized to the equivalent of lower altitudes for this reason. But in light of these findings, the researchers noted passengers may feel better with higher pressurized cabins during flights, but may also lose a potential advantage of recovering from jetlag. And in light of the effects of lower oxygen levels, the researchers now want to see what higher oxygen levels may do to the circadian clock.
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Researchers Track Effects Of Changing Ocean Temperature On Phytoplankton
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"Synechococcus and other phytoplankton are sentinels," says WHOI biologist Heidi Sosik, who initiated the study. "They tell us how an ecosystem is responding to shifts in climate."
As ocean temperatures increased during the study period, annual blooms of Synechococcus occurred up to four weeks earlier, researchers found, because cells divide faster in warmer waters. Such shifts could have major effects on marine ecosystems worldwide, according to Sosik.
If ocean temperatures continue warming over the next century, some ecosystems could become dominated by small phytoplankton, eventually leading to changes that could affect larger species like fish, whales and birds, Sosik says.
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Although Sosik and colleagues saw that Synechococcus cells reproduced faster than usual as conditions warmed, the overall size of the phytoplankton bloom didn't increase much during the course of the study. As the bacteria grew more quickly, tiny protozoa, viruses and other single-celled organisms that prey on Synechococcus consumed them more quickly.
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"Looking at physiology at the species level is a holy grail in marine ecology," Sosik says. "Each species interacts with its environment in a different way, so to understand the effects of something like temperature, it's critical to be able to study a single species. Doing that every hour, every day, every year gave us a very high-resolution picture. There's nothing like this out there."
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Chemistry
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The Cost Of Plastic Packaging
The changes have happened so gradually that most consumers haven’t even noticed, but a tremendous amount of plastics have crept onto supermarket shelves. Shoppers are tossing a lot of plastic packages into their carts that didn’t exist when they were kids. Cucumbers sleeved in polyethylene film are now ubiquitous in the produce department, as are sliced fruits in polyethylene terephthalate (PET) containers and chopped, ready-to-eat salads in polypropylene bags. People don’t have to make their own guacamole or hummus anymore—it comes already prepared in convenient polypropylene tubs.
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To McDonough and like-minded critics, flexible plastics, especially the newer multilayered films, are another excess of a throwaway society. They are much harder to recycle than the simpler metal, paper, and glass containers they replace. Too many of the new materials end up in landfills or bobbing around the ocean. And they make it all too easy for people to simply discard things without a thought to the damage they are doing to the planet.
The packaging industry, though, doesn’t think its products are so stupid. It sees plastics as a solution to another big environmental problem: food waste. Flexible plastics don’t shatter or dent, and if they are well-engineered, they don’t rip or puncture either. Their multilayered structures ensure long-term preservation of the food inside. And they are lighter and cheaper to transport than metals or glass.
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Environmental advocates acknowledge the benefits that multilayer packages bring. Unlike other contentious products of the plastic industry, such as plastic bags and polystyrene foam, they aren’t being targeted for outright bans. But environmental activists argue that the industry should do something about the packaging waste that is mounting in the environment.
Everyone acknowledges that multilayer flexible containers are more difficult to recycle than simpler packages like aluminum cans or PET bottles. The layers can’t be separated, so they are shredded and re-extruded into plastic pellets together. Often they are relegated to lower value uses such as plastic lumber for park benches rather than new packages. Activists think of such downgrading, called cascaded recycling, as a last resort.
[Editors Note; This is a good article that contains lots of information and I think presents both sides of the cost/benefit discussion pretty well... ymmv]
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Self Healing Lithium-Ion Battery Developed
Scientists in China and South Korea have created self-healing, flexible batteries that could one day find use in wearable electronic devices.
Wearable technology, such as activity trackers, augmented reality glasses and even light-up Bluetooth cocktail dresses, is growing in popularity. However, developing durable power sources that can safely withstand the strains of everyday activities remains a challenge.
Now, a collaboration between Samsung and researchers at Fudan University in Shanghai has developed flexible lithium-ion batteries that can grow back together after being broken apart, without losing their electrochemical functionality.
The batteries are formed of layers of carbon nanotubes which are loaded with lithium nanoparticles and fixed onto a self-healing polymer. A cellulose-based gel acts both as an electrolyte and separating layer between the electrodes. After being cut in two, the battery can self-repair when the two sections are simply held together for a few seconds. The battery maintains its electronic performance even after several rounds of cutting and healing.
Its unique structure also prevents lithium compounds from leaking out of the electrodes after the device has sustained damage, a significant safety hazard with current products.
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Ecology
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Scientists Find Link Between Tropical Storms And Decline Of River Deltas
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Deltas are landforms made from sediment washed into rivers and carried downstream. The sediment builds up where the river meets slow moving or still water, such as seas or lakes. Deltas naturally subside under their own weight, so a constant flow of new deposits is vital to offset these changes and prevent flooding which could be disastrous to agriculture and the environment.
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The Mekong is the world’s third largest river delta at 39,000 square kilometres. It’s home to 20 million people and has a large agricultural area which is dominated by rice and is vital to the economy of Vietnam.
The international team behind this latest research developed a new method of analysing archived measurements of water discharge into the Mekong River to detect sediment concentration dating back over two decades (1981-2005). Then, by modelling the water flows through the Mekong’s channels, they were able to isolate the impact of changes in tropical storms on the river’s sediment load. Their data shows that of all the sediment transported to the delta, one third is due to tropical cyclones. It also shows that the Mekong’s sediment load has declined markedly in recent years – largely due to changes in the location and intensity of storms tracking across the upstream rivers that feed the delta.
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[Lead researcher Professor Stephen Darby of the University of Southampton] commented: “These results are very significant because the Mekong’s sediment load is already declining as a result of upstream damming and other human impacts such as sand mining. Understanding the role played by changes in tropical cyclone climatology gives us a broader knowledge of the threats facing this delta and others like it around the world.”
The research has implications globally because other major rivers such as the Ganges (India/Bangladesh), Yangtze (China) and Mississippi (USA) have catchments that are regularly struck by tropical storms. Some 500 million people live and work in the world’s major river deltas. This study indicates that changes in storm climatology, even in the river catchments far upstream of the deltas themselves, must also be considered when evaluating their future vulnerability to sea-level rise.
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New Perovskite Solar Cell Design Could Outperform Existing Commercial Technologies
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“Perovskite semiconductors have shown great promise for making high-efficiency solar cells at low cost,” said study co-author Michael McGehee, a professor of materials science and engineering at Stanford. “We have designed a robust, all-perovskite device that converts sunlight into electricity with an efficiency of 20.3 percent, a rate comparable to silicon solar cells on the market today.”
The new device consists of two perovskite solar cells stacked in tandem. Each cell is printed on glass, but the same technology could be used to print the cells on plastic, McGehee added.
“The all-perovskite tandem cells we have demonstrated clearly outline a roadmap for thin-film solar cells to deliver over 30 percent efficiency,” said co-author Henry Snaith, a professor of physics at Oxford. “This is just the beginning.”
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“The efficiency of our tandem device is already far in excess of the best tandem solar cells made with other low-cost semiconductors, such as organic small molecules and microcrystalline silicon,” McGehee said. “Those who see the potential realize that these results are amazing.”
The next step is to optimize the composition of the materials to absorb more light and generate an even higher current, Snaith said.
“The versatility of perovskites, the low cost of materials and manufacturing, now coupled with the potential to achieve very high efficiencies, will be transformative to the photovoltaic industry once manufacturability and acceptable stability are also proven,” he said.
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Physics
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Scientists Manipulate Surfaces To Make Them Invisible
Most lenses, objectives, eyeglass lenses, and lasers come with an anti-reflective coating. Unfortunately, this coating works optimally only within a narrow wavelength range. Scientists at the Max Planck Institute for Intelligent Systems in Stuttgart have now introduced an alternative technology. Instead of coating a surface, they manipulate the surface itself. By comparison with conventional procedures, this provides the desired anti-reflective effect across a wider wavelength range. But more than this, it largely increases the light transmittance through surfaces. In the future, the nanostructured surfaces may improve high-energy lasers as well as touchscreens and the output of solar modules.
Researchers at the Max Planck Institute for Intelligent Systems took a page out of the design book for moth cornea. The corneas of these mostly nocturnal insects reflect almost no incoming light. There is no glow of light bouncing off the moth's eyes to betray their presence to potential predators. Less reflected light also means that moths are able to use practically all the scarce night-time light to see.
This magic from the world of insects inspired scientists to try the same tactics for the design of optical components. Like the corneas of moths, the components must allow light to pass through while light reflection is of little use. So far, component designers apply anti-reflective coating to lenses, display screens, monitors and laser components. However, these coatings have disadvantages. Most of them work only in a narrow wavelength range, and they produce lens errors dependent on the angle of light incidence.
Applying the moth cornea principle will put an end to these problems. Scientists at the Max Planck Institute for Intelligent Systems, Department for New Materials and Biosystems, under the guidance of Director Joachim Spatz had a good look at their natural model. Physicist Zhaolu Diao explains nature's design: "The eye surface is densely covered with column-like structures. They are only a few hundred nanometres high and taper conically toward the tip". The columns look like regularly spaced stalagmites on a cavern floor. As the light passes through this boundary layer, its refractive index changes continuously, starting from the ambient air to the materials of the outer moth eye layers.
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To imitate the moth eye principle, the scientists needed to find a way of turning smooth surfaces into nano-column landscapes. To accomplish this they developed a two-step process. In the first step, they deposited gold particles in a regular honeycomb pattern on a large surface. In this regular honeycomb pattern, the gold particles settle in the points of crossroad. In the second step, the gold-studded crossroads serve as mask in a chemical etching process. As a result, no material is etched away underneath the gold-studded crossroads, and the desired upright column-like structures remain. The structured surfaces covered as much as two by two centimetres.
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