“Our results have really exceeded the expectations we had when we started with the technique,” says the research leader Björn Wickman, from Chalmers’ Department of Physics. “Our new method makes it possible to reduce the mercury content in a liquid by more than 99%. This can bring the water well within the margins for safe human consumption.”

According to the World Health Organisation (WHO), mercury is one the most harmful substances for human health. It can influence the nervous system, the development of the brain, and more. It is particularly harmful for children and can also be transmitted from a mother to a child during pregnancy. Furthermore, mercury spreads very easily through nature, and can enter the food chain. Freshwater fish, for example, often contain high levels of mercury.

In the last two years, Björn Wickman and Cristian Tunsu, researcher at the Department of Chemistry and Chemical Engineering at Chalmers, have studied an electrochemical process for cleaning mercury from water. Their method works via extracting the heavy metal ions from water by encouraging them to form an alloy with another metal.

“Today, cleaning away the low, yet harmful, levels of mercury from large amounts of water is a major challenge. Industries need better methods to reduce the risk of mercury being released in nature,” says Björn Wickman.

Their new method involves a metal plate — an electrode — that binds specific heavy metals to it. The electrode is made of the noble metal platinum, and through an electrochemical process it draws the toxic mercury out of the water to form an alloy of the two. In this way, the water is cleaned of the mercury contamination. The alloy formed by the two metals is very stable, so there is no risk of the mercury re-entering the water.

“An alloy of this type has been made before, but with a totally different purpose in mind. This is the first time the technique with electrochemical alloying has been used for decontamination purposes,” says Cristian Tunsu.

One strength of the new cleaning technique is that the electrode has a very high capacity. Each platinum atom can bond with four mercury atoms. Furthermore, the mercury atoms do not only bond on the surface, but also penetrate deeper into the material, creating thick layers. This means the electrode can be used for a long time. After use, it can be emptied in a controlled way. Thereby, the electrode can be recycled, and the mercury disposed of in a safe way. A further positive for this process is that it is very energy efficient.

“Another great thing with our technique is that it is very selective. Even though there may be many different types of substance in the water, it just removes the mercury. Therefore, the electrode doesn’t waste capacity by unnecessarily taking away other substances from the water,” says Björn Wickman.

Patenting for the new method is being sought, and in order to commercialise the discovery, the new company Atium has been set up. The new innovation has already been bestowed with a number of prizes and awards, both in Sweden and internationally. The research and the colleagues in the company have also had a strong response from industry.

“We have already had positive interactions with a number of interested parties, who are keen to test the method. Right now, we are working on a prototype which can be tested outside the lab under real-world conditions.”

Read the article, “Effective removal of mercury from aqueous streams via electrochemical alloy formation on platinum” in Nature Communications.

Potential uses for the new method

The technique could be used to reduce the amount of waste and increase the purity of waste and process water in the chemical and mining industries, and in metal production. It can contribute to better environmental cleaning of places with contaminated land and water sources.

It can even be used to clean drinking water in badly affected environments because, thanks to its low energy use, it can be powered totally by solar cells. Therefore, it can be developed into a mobile and reusable water cleaning technology.

More on heavy metals in our environment

Heavy metals in water sources create enormous environmental problems and influence the health of millions of people around the world. Heavy metals are toxic for all living organisms in the food chain. According to the WHO, mercury is one of the most dangerous substances for human health, influencing our nervous system, brain development and more. The substance is especially dangerous for children and unborn babies.

Today there are strict regulations concerning the management of toxic heavy metals to hinder their spread in nature. But there are many places worldwide which are already contaminated, and they can be transported in rain or in the air. This results in certain environments where heavy metals can become abundant, for example fish in freshwater sources.

In industries where heavy metals are used, there is a need for better methods of recycling, cleaning and decontamination of the affected water.

This is one of six species of cactus subjected to careful testing by University of Illinois postdoctoral researcher Stephanie Crofts and animal biology professor Philip Anderson. The researchers, who study the biomechanics of puncturing plants and animals, wanted to know how spine structure influences its performance.

They found that the same biomechanical traits that allow cholla thorns and other barbed spines to readily penetrate animal flesh also make the spines more difficult to dislodge. The researchers report their findings in the Proceedings of the Royal Society B.

“We’re looking at the fundamental mechanics of a puncture event and how differences in cactus spines — in particular their microstructure — affect how they puncture and anchor into whatever they’re puncturing,” Crofts said.

In addition to cholla, the researchers evaluated the spines of Echinocactus grusonii, the golden barrel cactus; Opuntia fragilis, or brittle prickly pear; Pereskia grandiflora, the rose cactus; Echinopsis terscheckii, the Argentine saguaro; and Opuntia polyacantha, the plains prickly pear.

Cactus spines may have a variety of functions, including defending the plant from predators, providing shade and collecting water from fog. Cholla spines have a reproductive purpose: By latching on to any critter unlucky enough to brush past them, the spines help the plant distribute pieces of itself to new locations.

To compare the different spines, Crofts and Anderson tested them in skinless chicken breasts, pork shoulders (with the skin) and synthetic elastomers of differing densities. They measured how much force was required to puncture — and withdraw from — each material with each type of spine.

“Before we started the experiments, we looked at the spines under a scanning electron microscope,” Crofts said. “The barbed spines — like those on the cholla — looked incredibly similar to porcupine quills studied by other groups.”

Like porcupine quills, barbed cactus spines have a shingled appearance, the result of overlapping layers of barbs. And, like those on the porcupine quills, the cactus barbs are just the right size to snag animal muscle fibers, the researchers discovered.

Spines without barbs required more work to initiate fracture, the researchers found. Barbed spines more readily penetrated their targets and required less work to do so. They also were more difficult to remove from animal tissue.

“In order to puncture effectively, the cholla spine has to be able to penetrate the target very easily, so that just a slight brushing is all it takes,” Anderson said. “At the same time, it has to be really hard to remove.”

In porcupine quills and barbed cactus spines, the barbs act like little sharpened blades that concentrate the stress and cause the animal tissue to fracture more easily, Anderson said.

“Then the barbs catch on your muscle fibers, making it difficult to remove them,” he said.

The researchers detected reliable differences in performance between the cactus species. For example, O. polyacantha “required significantly more work to withdraw from the chicken than any other species,” the team found. Cholla spines were significantly more difficult to withdraw from pig tissue. In fact, a single cholla spine could hoist a half-pound hunk of pork up by its skin.

The cringe-worthy findings went further. Barbed spines removed from chicken breast ended up with a coating of animal tissue, the team found. Barbed spines in pig flesh came out clean, but missing some of their barbs. Those, presumably, remained in the flesh.

“In the United States, traffic noise can be heard nearly everywhere,” said Jennifer Tennessen, first author of the paper who was a graduate student at Penn State at the time of the research and is currently a research associate at Western Washington University. “Noise can have a number of negative consequences on wildlife, for example by interfering with communication and reducing the ability to find food. Frogs are particularly vulnerable to noise because they rely on sound to find mates and reproduce. Wood frogs travel to ponds in the spring to mate and lay their eggs, but many of these ponds are located near noisy roads. We wanted to know if traffic noise has negative physiological effects on wood frogs and, if so, whether they can adapt.”

The researchers collected eggs from ponds located less than 300 feet from interstates and major highways and from ponds in more isolated settings, up to 3 miles from major roads. The eggs were raised through metamorphosis in the lab, and the resulting frogs were exposed either to traffic noise or to ambient noise similar to that at the quiet ponds for 8 days, about the length of time they would spend at breeding ponds.

The researchers found that frogs from the quiet ponds had increased levels of the stress hormone corticosterone after exposure to traffic noise for 8 days, indicating that the noise is stressful. Noise exposure also affected immune function in frogs from quiet sites, increasing counts of a type of white blood cell called monocytes — an indication of an immune response to noise — and impairing the production of important compounds on the skin called antimicrobial peptides.

“In frogs from quiet ponds, exposure to traffic noise impaired the ability to produce antimicrobial peptides in the brevinin and temporin families,” said Louise Rollins-Smith, professor of pathology, microbiology, and immunology at the Vanderbilt University School of Medicine and an author of the paper. “Antimicrobial peptides are components of the immune defense system that provide important protection against pathogens like bacteria and fungi. Brevinin-family peptides in particular strongly inhibit the fungal pathogen that causes the infectious disease chytridiomycosis, or chytrid, which is responsible for widespread mortality of amphibians around the world.”

The researchers also investigated whether frogs have developed ways to deal with these negative consequences of traffic noise.

“Long term elevation of stress hormones can lead to negative immune consequences,” said Tracy Langkilde, professor and head of biology at Penn State and senior author of the paper. “So we might expect to see suppression of the stress response after long-term stress exposure to reduce immune costs, such as the altered production of skin peptides that we documented here. In frogs from noisy ponds, we see just that.”

Frogs from noisy ponds did not have elevated levels of corticosterone after exposure to traffic noise for 8 days, suggesting that frogs from ponds in high-noise areas have a suppressed stress response.

“We’re not sure if the frogs from noisy sites have a suppressed stress response to noise specifically or if they have a suppressed stress response overall,” said Langkilde. “Both offer the benefit of avoiding stress-related costs of noise, but having a dampened stress response in general could have other negative effects, for example not being able to properly mount a behavioral response to predators.”

Unlike frogs from quiet ponds, which had increased monocyte counts when exposed to traffic noise, frogs from noisy ponds actually had increased monocyte counts when exposed to the ambient noise heard at quiet ponds. The researchers believe that this kind of immune response may happen in unfamiliar situations, and supports the idea that frogs from noisy sites have adapted to avoid the physiological costs of noise.

“In the future, we hope to pinpoint the mechanism of how frogs are adapting to noise,” said Tennessen. “The roads near the ponds we studied were built between the 1940s and 1960s, so these changes may have occurred within 15 to 35 frog generations. People usually think of adaptation and evolution occurring over huge timescales, but here we see that animals can respond relatively quickly to new threats, though the consequences of that response are still unclear.”

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The team used state-of-the art instrumentation at the W. M. Keck Observatory on Maunakea, Hawaii to confirm the existence of water in the planet’s atmosphere, as well as a lack of methane.

While other researchers had previously made similar measurements of this planet, these new, more robust data demonstrate the power of combining high-resolution spectroscopy with a technique known as adaptive optics, which corrects for the blurring effect of Earth’s atmosphere.

“This type of technology is exactly what we want to use in the future to look for signs of life on an Earth-like planet. We aren’t there yet but we are marching ahead,” says Dimitri Mawet, an associate professor of astronomy at Caltech and a research scientist at JPL, which Caltech manages for NASA.

Mawet is co-author of a new paper on the findings published today in the Astronomical Journal. The lead author is Ji Wang, formerly a postdoctoral scholar at Caltech and now an assistant professor at Ohio State University.

Taking pictures of planets that orbit other stars — exoplanets — is a formidable task. Light from the host stars far outshines the planets, making them difficult to see.

More than a dozen exoplanets have been directly imaged so far, including HR 8799c and three of its planetary companions. In fact, HR 8799 is the only multiple-planet system to have its picture taken. Discovered using adaptive optics on the Keck II telescope, the direct images of HR8799 are the first-ever of a planetary system orbiting a star other than our sun.

Once an image is obtained, astronomers can use instruments, called spectrometers, to break apart the planet’s light, like a prism turning sunlight into a rainbow, thereby revealing the fingerprints of chemicals. So far, this strategy has been used to learn about the atmospheres of several giant exoplanets.

The next step is to do the same thing only for smaller planets that are closer to their stars (the closer a planet is to its star and the smaller its size, the harder is it to see).

The ultimate goal is to look for chemicals in the atmospheres of Earth-like planets that orbit in the star’s “habitable zone” — including any biosignatures that might indicate life, such as water, oxygen, and methane.

Mawet’s group hopes to do just this with an instrument on the upcoming Thirty Meter Telescope, a giant telescope being planned for the late 2020s by several national and international partners, including Caltech.

But for now, the scientists are perfecting their technique using Keck Observatory — and, in the process, learning about the compositions and dynamics of giant planets.

“Right now, with Keck, we can already learn about the physics and dynamics of these giant exotic planets, which are nothing like our own solar system planets,” says Wang.

In the new study, the researchers used an instrument on the Keck II telescope called NIRSPEC (near-infrared cryogenic echelle spectrograph), a high-resolution spectrometer that works in infrared light.

They coupled the instrument with Keck Observatory’s powerful adaptive optics, a method for creating crisper pictures using a guide star in the sky as a means to measure and correct the blurring turbulence of Earth’s atmosphere.

This is the first time the technique has been demonstrated on directly imaged planets using what’s known as the L-band, a type of infrared light with a wavelength of around 3.5 micrometers, and a region of the spectrum with many detailed chemical fingerprints.

“The L-band has gone largely overlooked before because the sky is brighter at this wavelength,” says Mawet. “If you were an alien with eyes tuned to the L-band, you’d see an extremely bright sky. It’s hard to see exoplanets through this veil.”

The researchers say that the addition of adaptive optics made the L-band more accessible for the study of the planet HR 8799c. In their study, they made the most precise measurements yet of the atmospheric constituents of the planet, confirming it has water and lacks methane as previously thought.

“We are now more certain about the lack of methane in this planet,” says Wang. “This may be due to mixing in the planet’s atmosphere. The methane, which we would expect to be there on the surface, could be diluted if the process of convection is bringing up deeper layers of the planet that don’t have methane.”

The L-band is also good for making measurements of a planet’s carbon-to-oxygen ratio — a tracer of where and how a planet forms. Planets form out of swirling disks of material around stars, specifically from a mix of hydrogen, oxygen, and carbon-rich molecules, such as water, carbon monoxide, and methane.

These molecules freeze out of the planet-forming disks at different distances from the star — at boundaries called snowlines. By measuring a planet’s carbon-to-oxygen ratio, astronomers can thus learn about its origins.

Mawet’s team is now gearing up to turn on their newest instrument at Keck Observatory, called the Keck Planet Imager and Characterizer (KPIC). It will also use adaptive optics-aided high-resolution spectroscopy but can see planets that are fainter than HR 8799c and closer to their stars.

“KPIC is a springboard to our future Thirty Meter Telescope instrument,” says Mawet. “For now, we are learning a great deal about the myriad ways in which planets in our universe form.”

One type relies on memories from past experiences. The other on rhythm. Both are critical to our ability to navigate and enjoy the world.

New University of California, Berkeley, research shows the neural networks supporting each of these timekeepers are split between two different parts of the brain, depending on the task at hand.

“Whether it’s sports, music, speech or even allocating attention, our study suggests that timing is not a unified process, but that there are two distinct ways in which we make temporal predictions and these depend on different parts of the brain,” said study lead author Assaf Breska, a postdoctoral researcher in neuroscience at UC Berkeley.

The findings, published online in the Proceedings of the National Academy of Sciences journal, offer a new perspective on how humans calculate when to make a move.

“Together, these brain systems allow us to not just exist in the moment, but to also actively anticipate the future,” said study senior author Richard Ivry, a UC Berkeley neuroscientist.

Breska and Ivry studied the anticipatory timing strengths and deficits of people with Parkinson’s disease and people with cerebellar degeneration.

They connected rhythmic timing to the basal ganglia, and interval timing — an internal timer based largely on our memory of prior experiences — to the cerebellum. Both are primal brain regions associated with movement and cognition.

Moreover, their results suggest that if one of these neural clocks is misfiring, the other could theoretically step in.

“Our study identifies not only the anticipatory contexts in which these neurological patients are impaired, but also the contexts in which they have no difficulty, suggesting we could modify their environments to make it easier for them to interact with the world in face of their symptoms,” Breska said.

Non-pharmaceutical fixes for neurological timing deficits could include brain-training computer games and smartphone apps, deep brain stimulation and environmental design modifications, he said.

To arrive at their conclusion, Breska and Ivry compared how well Parkinson’s and cerebellar degeneration patients used timing or “temporal” cues to focus their attention.

Both groups viewed sequences of red, white and green squares as they flashed by at varying speeds on a computer screen, and pushed a button the moment they saw the green square. The white squares alerted them that the green square was coming up.

In one sequence, the red, white and green squares followed a steady rhythm, and the cerebellar degeneration patients responded well to these rhythmic cues.

In another, the colored squares followed a more complex pattern, with differing intervals between the red and green squares. This sequence was easier for the Parkinson’s patients to follow, and succeed at.

“We show that patients with cerebellar degeneration are impaired in using non-rhythmic temporal cues while patients with basal ganglia degeneration associated with Parkinson’s disease are impaired in using rhythmic cues,” Ivry said.

Ultimately, the results confirm that the brain uses two different mechanisms for anticipatory timing, challenging theories that a single brain system handles all our timing needs, researchers said.

“Our results suggest at least two different ways in which the brain has evolved to anticipate the future,” said Breska.

“A rhythm-based system is sensitive to periodic events in the world such as is inherent in speech and music,” he added. “And an interval system provides a more general anticipatory ability, sensitive to temporal regularities even in the absence of a rhythmic signal.”