Astronomy
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Venus Express Probe Reveals The Planet’s Mysterious Night Side
Venus’ atmosphere is as mysterious as it is dense and scorching. For generations, scientists have sought to study it using ground-based telescopes, orbital missions, and the occasional atmospheric probe. And in 2006, the ESA’s Venus Express mission became the first probe to conduct long-term observations of the planet’s atmosphere, which revealed much about its dynamics.
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Since the 1960s, astronomers have been aware that Venus’ atmosphere behaves much differently that those of other terrestrial planets. Whereas Earth and Mars have atmospheres that co-rotate at approximately the same speed as the planet, Venus’ atmosphere can reach speeds of more than 360 km/h (224 mph). So while the planet takes 243 days to rotate once on its axis, the atmosphere takes only 4 days.
This phenomena, known as “super-rotation”, essentially means that the atmosphere moves over 60 times faster than the planet itself. In addition, measurements in the past have shown that the fastest clouds are located at the upper cloud level, 65 to 72 km (40 to 45 mi) above the surface. Despite decades of study, atmospheric models have been unable to reproduce super-rotation, which indicated that some of the mechanics were unknown.
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From this information, it seems that topography and elevation are linked when it comes to Venus’ atmospheric behavior, but not consistently. So the standing waves observed on Venus’ night side may be the result of some other undetected mechanism at work. Alas, it seems that Venus’ atmosphere – in particular, the key aspect of super-rotation – still has some mysteries for us.
Puffed-Up Hot Jupiter Is Surprisingly Dark
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WASP-12b is a gaseous giant orbiting a Sun-like star once a day, close enough to be roasted by stellar radiation. The planet has taken the shape of a football due to strong tidal forces. The same forces cause the planet to always face the same side to its star, which makes the dayside temperature rise to a toasting 3100°C. The extreme heat not only prevents the formation of clouds, which could reflect some light back to space, but it also dissociates hydrogen molecules (H2) into hydrogen atoms (H), which absorb even more light.
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Probing WASP-12b’s Atmospheric Chemistry
Previous observations using transmission spectroscopy, which probes a sliver of atmosphere at the boundary between night and day, have showed hints of a titanium oxide haze — a powerful heat absorber. But it can’t contribute to the low reflectivity that Bell’s team found. “Our observations firmly reject such a model for the planet's dayside, which is not overly surprising as we would expect the dayside would be far too hot for this haze to exist,” Bell says.
But with a difference of 1000°C between the planet’s nightside and dayside, each side might exhibit completely different chemistries. “It’s entirely possible,” Bell adds, “that such haze may form closer to the night side of the planet and affect the transit observations.”
Biology
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CCNY-Led Research Team Identifies
New Organelle In Parasitic Wasp Venom
City College of New York biologist Shubha Govind and her research team have identified the composition of “virus-like particles" (VLPs) found in the venom of a wasp that is a parasite of fruit flies. Invisible to the eye, wasp VLPs suppress the flies’ immune responses by killing their blood cells.
Wasps lay their eggs along with spiked VLP particles into the worm-like immature bodies of Drosophila melanogaster, the long-venerated genetic model of human disease and development. In the wild, parasitic wasps attack insects and are used to naturally control crop damage by insect pests. The Govind lab has developed a model to study this host/parasite interaction in the laboratory. While the particles were originally termed “virus like” due to their size and structure, this work has shifted that view.
The new study reports that VLPs have a profile of “extracellular microvesicles” that are microscopic, membrane-bound transport structures most animal cells use to package and traffic proteins to the outside. Strikingly, VLPs also have proteins that resemble bacterial proteins, found on their needle-shaped “injectisome” used to invade animal cells. The VLP proteins are similarly located on their surfaces/spikes, suggesting parallel mechanisms of invading hosts’ blood cells.
Given the VLP particles’ mixed prokaryotic/eukaryotic properties, the researchers have renamed them MSEVs for “Mixed Strategy Extracellular Vesicles.”
Why Poison Frogs Don’t Poison Themselves
Don’t let their appearance fool you: Thimble-sized, dappled in cheerful colors and squishy, poison frogs in fact harbor some of the most potent neurotoxins we know. With a new paper published in the journal Science, scientists are a step closer to resolving a related head-scratcher — how do these frogs keep from poisoning themselves? And the answer has potential consequences for the fight against pain and addiction.
The new research, led by scientists at The University of Texas at Austin, answers this question for a subgroup of poison frogs that use the toxin epibatidine. To keep predators from eating them, the frogs use the toxin, which binds to receptors in an animal’s nervous system and can cause hypertension, seizures, and even death. The researchers discovered that a small genetic mutation in the frogs — a change in just three of the 2,500 amino acids that make up the receptor — prevents the toxin from acting on the frogs’ own receptors, making them resistant to its lethal effects. Not only that, but precisely the same change appeared independently three times in the evolution of these frogs.
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Changing the Lock
A receptor is a type of protein on the outside of cells that transmits signals between the outside and the inside. Receptors are like locks that stay shut until they encounter the correct key. When a molecule with just the right shape comes along, the receptor gets activated and sends a signal.
The receptor that Tarvin and her colleagues studied sends signals in processes like learning and memory, but usually only when a compound that is the healthy “key” comes into contact with it. Unfortunately for the frogs’ predators, toxic epibatidine also works, like a powerful skeleton key, on the receptor, hijacking cells and triggering a dangerous burst of activity.
The researchers found that poison frogs that use epibatidine have developed a small genetic mutation that prevents the toxin from binding to their receptors. In a sense, they’ve blocked the skeleton key. They also have managed, through evolution, to retain a way for the real key to continue to work, thanks to a second genetic mutation. In the frogs, the lock became more selective.
Chemistry
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Phosphorus Chlorides
Phosphorus chlorides have a distinct dual personality. They are remarkably constructive – rarely directly of use themselves but each is an important contributor of building blocks to other compounds. Unfortunately, though, some of those final products can be used in chemical weapons. This means that phosphorus chlorides are controlled under the Chemical Weapons Convention, appearing in schedule 3, which indicates that they are widely used outside weapons production.
The most prolific is phosphorus trichloride – PCl3 – with hundreds of thousands of tonnes produced annually. White phosphorus, itself derived from mined calcium phosphate, is reacted with chlorine to produce this colourless liquid. Although phosphorus trichloride can be used in some organic synthesis processes, its industrial strength is as the route to other compounds containing phosphorus and chlorine, notably phosphorus pentachloride, phosphoryl chloride (which has an added oxygen atom) and thiophosphoryl chloride with an added sulfur atom, best known as the starting point for some organophosphate insecticides. Phosphorus trichloride is also essential in the production of the weedkiller glyophosate used in products such as Roundup.
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The second subsidiary chloride, phosphoryl chloride, is a colourless liquid like its parent, made by reacting the phosphorus trichloride with oxygen or phosphorus pentoxide. As is becoming a distinct theme, phosphoryl chloride’s main value is in the production of other compounds – mostly esters. For example, a major product is triphenyl phosphate, which acts as a flame retardant in everything from electronics to glues. It is also used as a plasticiser, giving body to lacquers and varnishes, notably in nail polish.
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There is no doubt that these compounds and their derivatives have significant positive uses, but many of them are also dangerous. Phosphorus trichloride is very toxic, while both the pentachloride and phosphoryl chloride have to be treated with caution as they react dramatically with water, releasing corrosive hydrogen chloride gas. Many of the organophosphate insecticides derived from the chlorides can also act as nerve agents on humans. Of all the derivatives, though, tricresyl phosphate has done the most harm. It was used as an intentional adulterant to the Jamaica ginger extract known as ‘jake’ which was sold as patent medicine, but in practice largely used as a bootleg form of alcohol. US authorities in the 1920s, during prohibition, required the product to be made less drinkable, usually by adding so much ginger that it became unpleasant. But the California Extract Company discovered that by putting tricresyl phosphate in their ‘Superior Brand’ fluid extract of ginger, they could pass the government tests for solids content, but leave it still quite drinkable.
In a report for California and Western Medicine, Frank G. Crandall observed in 1931: ‘When the Volstead Act became a law and they were deprived of their usual toddy or daily drink of whisky, they could not afford to pay bootleggers’ prices or buy prescription whisky, so they bought their fluid extract of ginger. It was the poor man’s way of getting a drink of liquor.’ It was thought at the time that the tricresyl phosphate was harmless, but in reality it is a neurotoxin. Many victims – numbers are put in the 30,000 to 50,000 range – lost the use of their feet and sometimes hands. The resultant paralysis, known as jake leg or jake walk even resulted in a number of songs, notably the Jake Walk Blues by the Allen Brothers. Another outbreak of tricresyl phosphate poisoning occurred in 1959 in Morocco, when thousands were affected by cooking oil contaminated by jet engine lubricant.
Ecology
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UMN Researchers Find Recipe For Forest Restoration
The good news: Recognizing the incredible value of forests in providing habitat, storing carbon dioxide, purifying water and more, people around the world are working to restore forests destroyed in the past by human activities such as logging and farming. The bad news: In some places, it’s practically impossible.
Among the toughest forests to regenerate are tropical dry forests, species-rich ecosystems found near the equator in regions that experience alternating wet and dry seasons. Over the past century most of these forests, which help keep water clean and provide valuable habitat for wildlife, were replaced by farms and cattle pastures. Now, as conservationists work to replant deforested areas, they’re finding that the already challenging, high-clay soils underlying them have been degraded to an extent that makes it hard for tree seedlings to sink their roots.
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To find out what works best for reestablishing tropical dry forests, the researchers planted seedlings of 32 native tree species in degraded soil or degraded soil amended with sand, rice hulls, rice hull ash or hydrogel (an artificial water-holding material). After two years, they found that tree species known for traits that make them drought tolerant, such as enhanced ability to use water and capture sunlight, survived better than other species. Some of the soil amendments helped get seedlings off to a good start, but by the end of the experiment there was no difference in survival with respect to soil condition.
“This study is important for a number of reasons,” Powers said. “First, it demonstrates that it is possible to grow trees on extremely degraded soils, which provides hope that we can indeed restore tropical dry forests. Second, it provides a general approach to screen native tree species for restoration trails based on their functional traits, which can be applied widely across the tropics. Third, it is a great example of CBS researchers partnering with Costa Rican foresters to achieve a shared restoration goal."
Old Fish Few And Far Between Under Fishing Pressure
Like old-growth trees in a forest, old fish in the ocean play important roles in the diversity and stability of marine ecosystems. Critically, the longer a fish is allowed to live, the more likely it is to successfully reproduce over the course of its lifetime, which is particularly important in variable environmental conditions.
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In forestry, a tree farm with only 20-year-old trees may be healthy and productive, but the loss of old-growth trees should not go unnoticed. The giant trees have unique traits that support a number of animal and plant species and make for a diverse, robust ecosystem. In a similar sense, the same is true for old fish.
“More age complexity among species can contribute to the overall stability of a community,” Barnett said. “If you trim away that diversity, you’re probably reducing the marine food web’s ability to buffer against change.”
The designation of an “old fish” varies from species to species, depending on life history. Some types of rockfish might live to 200 years, while few herring live past age 10.
Physics
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Ultra-Light Aluminum
If you drop an aluminum spoon in a sink full of water, the spoon will sink to the bottom. That's because aluminum, in its conventional form, is denser than water says Utah State University chemist Alexander Boldyrev. But if you restructure the common household metal at the molecular level, as Boldyrev and colleagues did using computational modeling, you could produce an ultra-light crystalline form of aluminum that's lighter than water.
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"My colleagues' approach to this challenge was very innovative," says Boldyrev, professor in USU's Department of Chemistry and Biochemistry. "They started with a known crystal lattice, in this case, a diamond, and substituted every carbon atom with an aluminum tetrahedron."
The team's calculations confirmed such a structure is a new, metastable, lightweight form of crystal aluminum. And to their amazement, it has a density of only 0.61 gram per cubic centimeter, in contrast to convention aluminum's density of 2.7 grams per cubic centimeter.
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"Spaceflight, medicine, wiring and more lightweight, more fuel-efficient automotive parts are some applications that come to mind," Boldyrev says. "Of course, it's very early to speculate about how this material could be used. There are many unknowns. For one thing, we don't know anything about its strength."