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ScienceDaily

Electrochemical method for extracting uranium, and potentially other metal ions, from solution

Fifty years ago, scientists hit upon what they thought could be the next rocket fuel. Carboranes — molecules composed of boron, carbon and hydrogen atoms clustered together in three-dimensional shapes — were seen as the possible basis for next-generation propellants due to their ability to release massive amounts of energy when burned.

It was technology that at the time had the potential to augment or even surpass traditional hydrocarbon rocket fuel, and was the subject of heavy investment in the 1950s and 60s.

But things didn’t pan out as expected.

“It turns out that when you burn these things you actually form a lot of sediment,” said Gabriel Ménard, an assistant professor in UC Santa Barbara’s Department of Chemistry and Biochemistry. In addition to other problems found when burning this so-called “zip fuel,” its residue also gummed up the works in rocket engines, and so the project was scrapped.

“So they made these huge stockpiles of these compounds, but they actually never used them,” Ménard said.

Fast forward to today, and these compounds have come back into vogue with a wide range of applications, from medicine to nanoscale engineering. For Ménard and fellow UCSB chemistry professor Trevor Hayton, as well as Tel Aviv University chemistry professor Roman Dobrovetsky, carboranes could hold the key to more efficient uranium ion extraction. And that, in turn, could enable things like better nuclear waste reprocessing and uranium (and other metal) recovery from seawater.

Their research — the first example of applying electrochemical carborane processes to uranium extraction — is published in a paper (link) that appears in the journal Nature.

Key to this technology is the versatility of the cluster molecule. Depending on their compositions these structures can resemble closed cages, or more open nests, due to control of the compound’s redox activity — its readiness to donate or gain electrons. This allows for the controlled capture and release of metal ions, which in this study was applied to uranium ions.

“The big advancement here is this ‘catch and release’ strategy where you can switch between two states, where one state binds the metal and another state releases the metal,” Hayton said.

Conventional processes, such as the popular PUREX process that extracts plutonium and uranium, rely heavily on solvents, extractants and extensive processing.

“Basically, you could say it’s wasteful,” Ménard said. “In our case, we can do this electrochemically — we can capture and release the uranium with the flip of a switch.

“What actually happens,” added Ménard, “is that the cage opens up.” Specifically, the formerly closed ortho-carborane becomes an opened nido- (“nest”) carborane capable of capturing the positively-charged uranium ion.

Conventionally, the controlled release of extracted uranium ions, however, is not as straightforward and can be somewhat messy. According to the researchers, such methods are “less established and can be difficult, expensive and or destructive to the initial material.”

But here, the researchers have devised a way to reliably and efficiently flip back and forth between open and closed carboranes, using electricity. By applying an electrical potential using an electrode dipped in the organic portion of a biphasic system, the carboranes can receive and donate the electrons needed to open and close and capture and release uranium, respectively.

“Basically you can open it up, capture uranium, close it back up and then release uranium,” Ménard said. The molecules can be used multiple times, he added.

This technology could be used for several applications that require the extraction of uranium and by extension, other metal ions. One area is nuclear reprocessing, in which uranium and other radioactive “trans-uranium” elements are extracted from spent nuclear material for storage and reuse (the PUREX process).

“The problem is that these trans-uranium elements are very radioactive and we need to be able to store these for a very long time because they’re basically very dangerous,” Ménard said. This electrochemical method could allow for the separation of uranium from plutonium, similar to the PUREX process, he explained. The extracted uranium could then be enriched and put back into the reactor; the other high-level waste can be transmuted to reduce their radioactivity.

Additionally, the electrochemical process could also be applied to uranium extraction from seawater, which would ease pressure on the terrestrial mines where all uranium is currently sourced.

“There’s about a thousand times more dissolved uranium in the oceans than there are in all the land mines,” Ménard said. Similarly, lithium — another valuable metal that exists in large reserves in seawater — could be extracted this way, and the researchers plan to take this research direction in the near future.

“This gives us another tool in the toolbox for manipulating metal ions and processing nuclear waste or doing metal capture out of oceans,” Hayton said. “It’s a new strategy and new method to achieve these types of transformations.”

Research in this study was conducted also by Megan Keener (lead author), Camden Hunt and Timothy G. Carroll at UCSB; and by Vladimir Kampel at Tel Aviv University.

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IEEE Spectrum

How Do Neural Implants Work?

It sounds like science fiction, but a neural implant could, many years from now, read and edit a person’s thoughts. Neural implants are already being used to treat disease, rehabilitate the body after injury, improve memory, communicate with prosthetic limbs, and more. 

The U.S. Department of Defense and the U.S. National Institutes of Health (NIH) have devoted hundreds of millions of dollars in funding toward this sector. Independent research papers on the topic appear in top journals almost weekly.

Here, we describe types of neural implants, explain how neural implants work, and provide examples demonstrating what these devices can do. 

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ScienceDaily

Bacteria-shredding tech to fight drug-resistant superbugs

Researchers have used liquid metals to develop new bacteria-destroying technology that could be the answer to the deadly problem of antibiotic resistance.

The technology uses nano-sized particles of magnetic liquid metal to shred bacteria and bacterial biofilm — the protective “house” that bacteria thrive in — without harming good cells.

Published in ACS Nano, the research led by RMIT University offers a groundbreaking new direction in the search for better bacteria-fighting technologies.

Antibiotic resistance is a major global health threat, causing at least 700,000 deaths a year. Without action, the death toll could rise to 10 million people a year by 2050, overtaking cancer as a cause of death.

The biggest issues are the spread of dangerous, drug-resistant superbugs and the growth of bacterial biofilm infections, which can no longer be treated with existing antibiotics.

Dr Aaron Elbourne said antibiotics had revolutionised health since they were discovered 90 years ago but were losing effectiveness due to misuse.

“We’re heading to a post-antibiotic future, where common bacterial infections, minor injuries and routine surgeries could once again become deadly,” Elbourne, a Postdoctoral Fellow in the Nanobiotechnology Laboratory at RMIT, said.

“It’s not enough to reduce antibiotic use, we need to completely rethink how we fight bacterial infections.

“Bacteria are incredibly adaptable and over time they develop defences to the chemicals used in antibiotics, but they have no way of dealing with a physical attack.

“Our method uses precision-engineered liquid metals to physically rip bacteria to shreds and smash through the biofilm where bacteria live and multiply.

“With further development, we hope this technology could be the way to help make antibiotic resistance history.”

Let’s get physical: New way to kill bacteria

The RMIT team behind the technology is the only group in the world investigating the antibacterial potential of magnetic liquid metal nanoparticles.

When exposed to a low-intensity magnetic field, these nano-sized droplets change shape and develop sharp edges

When the droplets are placed in contact with a bacterial biofilm, their movements and nano-sharp edges break down the biofilm and physically rupture the bacterial cells.

In the new study, the team tested the effectiveness of the technology against two types of bacterial biofilms (Gram-positive and Gram-negative).

After 90 minutes of exposure to the liquid metal nanoparticles, both biofilms were destroyed and 99% of the bacteria were dead. Importantly, laboratory tests showed the bacteria-destroying droplets did not affect human cells.

Postdoctoral Fellow Dr Vi Khanh Truong said the versatile technology could one day be used in a range of ways to treat infections.

“It could be used as a spray coating for implants, to make them powerfully antibacterial and reduce the high rates of infection for procedures like hip and knee replacements,” said Truong, currently at North Carolina State University on a Fulbright Scholarship to further the research.

“There’s also potential to develop this into an injectable treatment that could be used at the site of infection.”

The next stage for the research — testing the effectiveness of the technology in pre-clinical animal trials — is already underway, with the team hoping to move to clinical human trials in coming years.

Led by Truong, Elbourne and Dr James Chapman, the multi-disciplinary team is also planning to expand the technology beyond antibacterial treatment, exploring how it could be used to:

  • treat fungal infections — the next superbugs
  • break through cholesterol plaques and battle heart problems
  • stop tumours by being injected directly into cancer cells.

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ScienceDaily

Low-temp photocatalyst could slash the carbon footprint for syngas

Rice University engineers have created a light-powered nanoparticle that could shrink the carbon footprint of a major segment of the chemical industry.

The particle, tiny spheres of copper dotted with single atoms of ruthenium, is the key component in a green process for making syngas, or synthesis gas, valuable chemical feedstock that’s used to make fuels, fertilizer and many other products. Researchers from Rice, UCLA and the University of California, Santa Barbara (UCSB), describe the low-energy, low-temperature syngas production process this week in Nature Energy.

“Syngas can be made in many ways, but one of those, methane dry reforming, is increasingly important because the chemical inputs are methane and carbon dioxide, two potent and problematic greenhouse gases,” said Rice chemist and engineer Naomi Halas, a co-corresponding author on the paper.

Syngas is a mix of carbon monoxide and hydrogen gas that can be made from coal, biomass, natural gas and other sources. It’s produced at hundreds of gasification plants worldwide and is used to make fuels and chemicals worth more than $46 billion per year, according to a 2017 analysis by BCC Research.

Catalysts, materials that spur reactions between other chemicals, are critical for gasification. Gasification plants typically use steam and catalysts to break apart hydrocarbons. The hydrogen atoms pair up to form hydrogen gas, and the carbon atoms combine with oxygen in the form of carbon monoxide. In dry reforming, the oxygen atoms come from carbon dioxide rather than steam. But dry reforming hasn’t been attractive to industry because it typically requires even higher temperatures and more energy than steam-based methods, said study first author Linan Zhou, a postdoctoral researcher at Rice’s Laboratory for Nanophotonics (LANP).

Halas, who directs LANP, has worked for years to create light-activated nanoparticles that insert energy into chemical reactions with surgical precision. In 2011, her team showed it could boost the amount of short-lived, high-energy electrons called “hot carriers” that are created when light strikes metal, and in 2016 they unveiled the first of several “antenna reactors” that use hot carriers to drive catalysis.

One of these, a copper and ruthenium antenna reactor for making hydrogen from ammonia, was the subject of a 2018 Science paper by Halas, Zhou and colleagues. Zhou said the syngas catalyst uses a similar design. In each, a copper sphere about 5-10 nanometers in diameter is dotted with ruthenium islands. For the ammonia catalysts, each island contained a few dozen atoms of ruthenium, but Zhou had to shrink these to a single atom for the dry reforming catalyst.

“High efficiency is important for this reaction, but stability is even more important,” Zhou said. “If you tell a person in industry that you have a really efficient catalyst they are going to ask, ‘How long can it last?'”

Zhou said the question is important for producers, because most gasification catalysts are prone to “coking,” a buildup of surface carbon that eventually renders them useless.

“They cannot change the catalyst every day,” Zhou said. “They want something that can last.”

By isolating the active ruthenium sites where carbon is dissociated from hydrogen, Zhou reduced the chances of carbon atoms reacting with one another to form coke and increased the likelihood of them reacting with oxygen to form carbon monoxide.

“But single-atom islands are not enough,” he said. “For stability, you need both single atoms and hot electrons.”

Zhou said the team’s experimental and theoretical investigations point to hot carriers driving hydrogen away from the reactor surface.

“When hydrogen leaves the surface quickly, it’s more likely to form molecular hydrogen,” he said. “It also decreases the possibility of a reaction between hydrogen and oxygen, and leaves the oxygen to react with carbon. That’s how you can control with the hot electron to make sure it doesn’t form coke.”

Halas said the research could pave the way “for sustainable, light-driven, low-temperature, methane-reforming reactions for production of hydrogen on demand.”

“Beyond syngas, the single-atom, antenna-reactor design could be useful in designing energy-efficient catalysts for other applications,” she said.

The technology has been licensed by Syzygy Plasmonics, a Houston-based startup whose co-founders include Halas and study co-author Peter Nordlander.

Halas is Rice’s Stanley C. Moore Professor of Electrical and Computer Engineering and professor of chemistry, bioengineering, physics and astronomy, and materials science and nanoengineering. Nordlander is the Wiess Chair and Professor of Physics and Astronomy, and professor of electrical and computer engineering, and materials science and nanoengineering.

Additional co-authors include Chao Zhang, Dayne Swearer, Shu Tian, Hossein Robatjazi, Minhan Lou, Liangliang Dong and Luke Henderson, all of Rice; John Mark Martirez and Emily Carter, both of UCLA; and Jordan Finzel and Phillip Christopher of UCSB.

The research was supported by the Welch Foundation, the Air Force Office of Scientific Research (FA9550-15-1-0022) and the Department of Defense.

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IEEE Spectrum

Long-lasting Lithium-Sulfur Battery Promises to Double EV Range

Lithium-sulfur batteries seem to be ideal successors to good old lithium-ion. They could in theory hold up to five times the energy per weight. Their low weight makes them ideal for electric airplanes: firms such as Sion Power and Oxis Energy are starting to test their lithium-sulfur batteries in aircraft. And they would be cheaper given their use of sulfur instead of the rare-earth metals used in the cathode today.

But the technology isn’t yet commercial mainly because of its short life span. The cathode starts falling apart after just 40 to 50 charge cycles.

By designing a novel robust cathode structure, researchers have now made a lithium-sulfur battery that can be recharged several hundred times. The cells have an energy capacity four times that of lithium-ion, which typically holds 150 to 200 watt-hours per kilogram (Wh/kg). If translatable to commercial devices, it could mean a battery that powers a phone for five days without needing to recharge, or quadruples the range of electric cars.

That’s unlikely to happen, since energy capacity drops when cells are strung together into battery packs. But the team still expects a “twofold increase at battery pack level when [the new battery is] introduced to the market,” says Mahdokht Shaibani, a mechanical and aerospace engineer at Australia’s Monash University who led the work published recently in the journal Science Advances.

Shaibani likens the sulfur cathode in a lithium-sulfur battery to a hard-working, overtaxed office worker. It can take on a lot, but the job demands cause stress and hurt productivity. In battery terms, during discharge the cathode soaks up a large amount of lithium ions, forming lithium sulfide. But in the process, it swells enormously, and then contracts when the ions leave during battery charging. This repeated volume change breaks down the cathode.

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IEEE Spectrum

Building a Quantum Computer From Off-the-Shelf Parts

A new technique for fabricating quantum bits in silicon carbide wafers could provide a scalable platform for future quantum computers. The quantum bits, to the surprise of the researchers, can even be fabricated from a commercial chip built for conventional computing.

The recipe was surprisingly simple: Buy a commercially available wafer of silicon carbide (a temperature-robust semiconductor used in electric vehicles, LED lights, solar cells, and 5G gear) and shoot an electron beam at it. The beam creates a deficiency in the wafer which behaves, essentially, as a single electron spin that can be manipulated electrically, magnetically, or optically.

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Hackster.io

#TBT: Jet Lag Wearable Update

For today’s #TBT, let’s update an old project, which could help you stay awake and happy during the winter months. (Eventually, this will be released as a badge!)

// https://www.hackster.io/glowascii/glowup-anti-sad-and-jet-lag-wearable-a25021
// https://makezine.com/2015/01/06/diy-sad-light-therapy-box/

// https://www.doityourself.com/stry/how-to-make-your-own-sad-light-box
// https://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/symptoms-causes/syc-20364651
// https://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/in-depth/seasonal-affective-disorder-treatment/art-20048298

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ScienceDaily

Improved 3D nanoprinting technique to build nanoskyscrapers

Nanowalls, nanobridges, nano “jungle gyms”: it could seem the description of a Lilliputian village, but these are actual 3D-printed components with tremendous potential applications in nanoelectronics, smart materials and biomedical devices. Researchers at the Center for Soft and Living Matter (CSLM), within the Institute for Basic Science (IBS, South Korea) have improved the 3D nanoprinting process that enables to build precise, self-stacked, tall-and-narrow nanostructures. As shown in their latest publication in Nano Letters, the team also used this technique to produce transparent nanoelectrodes with high optical transmission and controllable conductivity.

The near-field electrospinning (NFES) technique consists of a syringe filled with a polymer solution suspended above a platform, which collects the ejected nanofiber and is pre-programmed to move left-and-right, back-and-forth, depending on the shape of the desired final product. The syringe and the platform have opposite charges, so that the polymer jet coming out from the needle of the syringe is attracted to the platform, forming a continuous fiber that solidifies on the platform. Since the electrospun jets are difficult to handle, this technique was limited to two-dimensional (2D) structures or hollow cylindrical three-dimensional (3D) structures, often with relatively large fiber diameters of a few micrometers.

IBS researchers were able to achieve a better control of the nanofiber deposition on the platform, by adding an appropriate concentration of sodium chloride (NaCl) to the polymer solution. This ensured the spontaneous alignment of the nanofiber layers stacked on top of each other forming walls.

“Although it is highly applicable to various fields, it is difficult to build stacked nanofibers with multiple designs using the conventional electrospinning techniques,” says Yoon-Kyoung Cho, the corresponding author of the study. “Our experiment showed that salt did the trick.”

The benefit provided by salt is related to the charges. The difference in voltage between the syringe and the platform creates positive charges in the polymer solution and negative charges in the platform, but a residual positive charge stays in the solidified fibers on the platform. The team found that applying salt to the polymer solution enhances the charge dissipation, leading to higher electrostatic attraction between the nanofiber jet and the fibers deposited on the platform.

Based on this mechanism, the team was able to produce tall-and-narrow nanowalls, with a minimum width of around 92 nanometers and a maximum height of 6.6 micrometers, and construct a variety of 3D nanoarchitectures, such as curved nanowall arrays, nano “jungle gyms,” and nanobridges, with controllable dimensions.

To demonstrate the potential application of these nanostructures, the researchers in collaboration with Hyunhyub Ko, professor at Ulsan National Institute of Science and Technology (UNIST), prepared 3D nanoelectrodes with silver-coated nanowalls embedded in transparent and flexible polydimethylsiloxane (PDMS) films. They confirmed that electrical resistance could be tuned with the number of nanofiber layers (the taller the nanowalls, the smaller the resistance), without affecting light transmission.

“Interestingly, this method can potentially avoid the trade-off between optical transmittance and sheet resistance in transparent electrodes. Arrays of 3D silver nanowires made with 20, 40, 60, 80, or 100 layers of nanofibers had variable conductivity, but stable light transmission of around 98%,” concludes Yang-Seok Park, the first author of the study.

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Smart intersections could cut autonomous car congestion

In the not-so-distant future, city streets could be flooded with autonomous vehicles. Self-driving cars can move faster and travel closer together, allowing more of them to fit on the road — potentially leading to congestion and gridlock on city streets.

A new study by Cornell researchers developed a first-of-its-kind model to control traffic and intersections in order to increase car capacity on urban streets, reduce congestion and minimize accidents.

“For the future of mobility, so much attention has been paid to autonomous cars,” said Oliver Gao, professor of civil and environmental engineering and senior author of the study, which published in Transportation Research Part B.

“If you have all these autonomous cars on the road, you’ll see that our roads and our intersections could become the limiting factor,” Gao said. “In this paper we look at the interaction between autonomous cars and our infrastructure on the ground so we can unlock the real capacity of autonomous transportation.”

The researchers’ model allows groups of autonomous cars, known as platoons, to pass through one-way intersections without waiting, and the results of a microsimulation showed it increased the capacity of vehicles on city streets up to 138% over a conventional traffic signal system, according to the study. The model assumes only autonomous cars are on the road; Gao’s team is addressing situations with a combination of autonomous and human-driven cars in future research.

Car manufacturers and researchers around the world are developing prototypes of self-driving cars, which are expected to be introduced by 2025. But until now, little research has focused on the infrastructure that will support these driverless cars.

Autonomous vehicles will be able to communicate with each other, offering opportunities for coordination and efficiency. The researchers’ model takes advantage of this capability, as well as smart infrastructure, in order to optimize traffic so cars can pass quickly and safely through intersections.

“Instead of having a fixed green or red light at the intersection, these cycles can be adjusted dynamically,” Gao said. “And this control can be adjusted to allow for platoons of cars to pass.”

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ScienceDaily

New tool uses AI to flag fake news for media fact-checkers

A new artificial intelligence (AI) tool could help social media networks and news organizations weed out false stories.

The tool, developed by researchers at the University of Waterloo, uses deep-learning AI algorithms to determine if claims made in posts or stories are supported by other posts and stories on the same subject.

“If they are, great, it’s probably a real story,” said Alexander Wong, a professor of systems design engineering at Waterloo. “But if most of the other material isn’t supportive, it’s a strong indication you’re dealing with fake news.”

Researchers were motivated to develop the tool by the proliferation of online posts and news stories that are fabricated to deceive or mislead readers, typically for political or economic gain.

Their system advances ongoing efforts to develop fully automated technology capable of detecting fake news by achieving 90 per cent accuracy in a key area of research known as stance detection.

Given a claim in one post or story and other posts and stories on the same subject that have been collected for comparison, the system can correctly determine if they support it or not nine out of 10 times.

That is a new benchmark for accuracy by researchers using a large dataset created for a 2017 scientific competition called the Fake News Challenge.

While scientists around the world continue to work towards a fully automated system, the Waterloo technology could be used as a screening tool by human fact-checkers at social media and news organizations.

“It augments their capabilities and flags information that doesn’t look quite right for verification,” said Wong, a founding member of the Waterloo Artificial Intelligence Institute. “It isn’t designed to replace people, but to help them fact-check faster and more reliably.”

AI algorithms at the heart of the system were shown tens of thousands of claims paired with stories that either supported or didn’t support them. Over time, the system learned to determine support or non-support itself when shown new claim-story pairs.

“We need to empower journalists to uncover truth and keep us informed,” said Chris Dulhanty, a graduate student who led the project. “This represents one effort in a larger body of work to mitigate the spread of disinformation.”

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