Computers Math

Metal-ion hybrid capacitors combine the properties of capacitors and batteries. One electrode uses the capacitive mechanism, the other the battery-type redox processes. Scientists have now scrutinized the role of anions in the electrolyte. The results, which have been published in the journal Angewandte Chemie, reveal the importance of sulfate anions. Sulfate-based electrolytes gave zinc-ion hybrid capacitors outstanding performance and extra-long operability.
Capacitors can uptake and release an enormous amount of charge in a short time, whereas batteries can store a lot of energy in a small volume. To combine both properties, scientists are investigating hybrid electrochemical cells, which contain both capacitor- and battery-type electrodes. Among these cells, researchers have identified metal-ion hybrid capacitors as especially promising devices. Here, the positive electrode includes pseudocapacitive properties, which means it can also store energy in the manner of a battery, by intercalation of the metal ions, while the negative electrode is made of a redox-active metal.
However, their electrolyte has long been neglected, says Chunyi Zhi who is investigating battery materials together with his team at the City University of Hong Kong. The researchers believe the type of electrolyte anion affects the performance of the device. “Paying more attention to the introduction of appropriate anions can effectively improve the power and energy density of a capacitor,” they say.
The researchers focused their attention on zinc-ion capacitors. This cell type consists of a zinc metal anode and a cathode made of titanium nitride nanofibers. The nanofibers are robust, and their porous surface allows the electrolyte to infiltrate. The scientists argue that the electrolyte anions, when attached to the titanium nitride surface, make the material more conductive. Moreover, the adsorbed anions may directly contribute to the charging process. The charging of the hybrid capacitor involves the extraction of the intercalated zinc ions.
Zhi and his colleagues compared the effects of three electrolyte anions: sulfate, acetate, and chloride. They looked at both their binding to the electrode surface and the performances of the electrochemical cells. It was a clear result.
The scientists reported that the sulfate anions stood out among the three anions. They observed that cells based on a zinc sulfate electrolyte performed best, and the sulfates bound stronger to the titanium nitride surface than the other anions. Moreover, sulfate-treated electrodes showed the lowest self-discharging. The authors attributed the findings to the electronic effects of sulfate. Its electron-pulling nature provides tight binding to the surface atoms and prevents the electrode from self-discharging, the authors concluded.
For a zinc-sulfate-based zinc-ion hybrid capacitor, the scientists reported high-performance operation for more than nine months. Moreover, these devices are flexible, which is especially useful for portable electronics. The scientists tested the device in an electronic watch and found excellent performance.

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Datacenters could benefit from lower cooling costs in part to ultra-fast electro-optic modulators developed by researchers in Japan using a polymer that is stable even at temperatures that would boil water.
Reported in the journal Nature Communications, the silicon-polymer hybrid modulators can transmit 200 gigabits of data per second at up to 110 °C and could enable optical data interconnections that are both extremely fast and reliable at high temperatures, reducing the need for cooling and expanding applications in harsh environments like rooftops and cars.
Demand for high-speed data transmission such as for high-definition media streaming has exploded in recent years, and optical communications are central to many of the necessary data connections. A critical component is the modulator, which puts data on a beam of light passing through an electro-optic material that can change its optical properties in response to an electric field.
Most modulators currently use inorganic semiconductors or crystals as the electro-optic material, but organic-based polymers have the advantages that they can be fabricated with excellent electro-optic properties at a low cost and operated at low voltages.
“Polymers have great potential for use in modulators, but reliability issues still need to be overcome for many industry applications,” explains Shiyoshi Yokoyama, professor of Kyushu University’s Institute for Materials Chemistry and Engineering and leader of the research collaboration.
One challenge is that parts of the molecules in the polymer layer must be organized through a process called poling to obtain good electro-optic properties, but this organization can be lost when the layer gets warm enough to begin softening — a point referred to as the glass transition temperature.

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However, if the modulators and other components can operate rapidly and reliably even at high temperatures, datacenters could run warmer, thereby reducing their energy usage — nearly 40% of which is currently estimated to go toward cooling.
Employing a polymer they designed to exhibit superb electro-optic properties and a high glass transition temperature of 172 °C through the incorporation of appropriate chemical groups, the research team achieved ultra-fast signaling at elevated temperatures in a silicon-polymer hybrid modulator based on a Mach-Zehnder interferometer configuration, which is less sensitive to temperature changes than some other architectures.
In the modulators, composed of multiple layers including the polymer and silicon, an incoming laser beam is split into two arms of equal length. Applying an electric field across the electro-optic polymer in one of the arms changes the optical properties such that the light wave slightly shifts. When the two arms come back together, interference between the modified and unmodified beams changes the strength of the mixed output beam depending on the amount of phase shift, thereby encoding data in the light.
Using a simple data signaling scheme of just on and off states, rates of over 100 Gbit/s were achieved, while a more complicated method using four signal levels could achieve a rate of 200 Gbit/s.
This performance was maintained with negligible changes even when operating the devices over temperatures ranging from 25 °C to 110 °C and after subjecting the devices to 90 °C heat for 100 hours, demonstrating the robustness and stability of the modulators over an extraordinarily wide range of temperatures.
“Stable operation even when the temperature fluctuates up to 110 °C is wonderful,” says Yokoyama. “This temperature range means operation in controlled environments such as datacenters, even at higher than normal temperatures, and many harsh environments where temperature is not well controlled is possible.”
The current devices are millimeter sized, making them relatively large compared to other designs, but the researchers are looking into ways to further reduce the footprint for incorporation of a dense arrays of such modulators in a small area.
“This kind of performance shows just how promising polymers are for future telecommunications technologies,” Yokoyama states.

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Electronic shirts that keep the wearer comfortably warm or cool, as well as medical fabrics that deliver drugs, monitor the condition of a wound and perform other tasks, may one day be manufactured more efficiently thanks to a key advance by Oregon State University researchers.
The breakthrough involves inkjet printing and materials with a crystal structure discovered nearly two centuries ago. The upshot is the ability to apply circuitry, with precision and at low processing temperatures, directly onto cloth — a promising potential solution to the longstanding tradeoff between performance and fabrication costs.
“Much effort has gone into integrating sensors, displays, power sources and logic circuits into various fabrics for the creation of wearable, electronic textiles,” said Chih-Hung Chang, professor of chemical engineering at Oregon State. “One hurdle is that fabricating rigid devices on cloth, which has a surface that’s both porous and non-uniform, is tedious and expensive, requiring a lot of heat and energy, and is hard to scale up. And first putting the devices onto something solid, and then putting that solid substrate onto fabric, is problematic too — it limits the flexibility and wearability of the fabric and also can necessitate cumbersome changes to the fabric manufacturing process itself.”
Chang and collaborators in the OSU College of Engineering and at Rutgers University tackled those challenges by coming up with a stable, printable ink, based on binary metal iodide salts, that thermally transforms into a dense compound of cesium, tin and iodine.
The resulting film of Cs2SnI6 has a crystal structure that makes it a perovskite.
Perovskites trace their roots to a long-ago discovery by a German mineralogist. In the Ural Mountains in 1839, Gustav Rose came upon an oxide of calcium and titanium with an intriguing crystal structure and named it in honor of Russian nobleman Lev Perovski.

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Perovskite now refers to a range of materials that share the crystal lattice of the original. Interest in them began to accelerate in 2009 after a Japanese scientist, Tsutomu Miyasaka, discovered that some perovskites are effective absorbers of light. Materials with a perovskite structure that are based on a metal and a halogen such as iodine are semiconductors, essential components of most electrical circuits.
Thanks to the perovskite film, Chang’s team was able to print negative-temperature-coefficient thermistors directly onto woven polyester at temperatures as low as 120 degrees Celsius — just 20 degrees higher than the boiling point of water.
A thermistor is a type of electrical component known as a resistor, which controls the amount of current entering a circuit. Thermistors are resistors whose resistance is temperature dependent, and this research involved negative-temperature-coefficient, or NTC, thermistors — their resistance decreases as the temperature increases.
“A change in resistance due to heat is generally not a good thing in a standard resistor, but the effect can be useful in many temperature detection circuits,” Chang said. “NTC thermistors can be used in virtually any type of equipment where temperature plays a role. Even small temperature changes can cause big changes in their resistance, which makes them ideal for accurate temperature measurement and control.”
The research, which included Shujie Li and Alex Kosek of the OSU College of Engineering and Mohammad Naim Jahangir and Rajiv Malhotra of Rutgers University, demonstrates directly fabricating high-performance NTC thermistors onto fabrics at half the temperature used by current state-of-the-art manufacturers, Chang said.
“In addition to requiring more energy, the higher temperatures create compatibility issues with many fabrics,” he said. “The simplicity of our ink, the process’ scalability and the thermistor performance are all promising for the future of wearable e-textiles.”
The Walmart Manufacturing Innovation Foundation and National Science Foundation supported this study. Findings were published in Advanced Functional Materials.

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Materials provided by Oregon State University. Original written by Steve Lundeberg. Note: Content may be edited for style and length. More

It’s not a stretch to say that stretchable sensors could change the way soft robots function and feel. In fact, they will be able to feel quite a lot.
Cornell University researchers have created a fiber-optic sensor that combines low-cost LEDs and dyes, resulting in a stretchable “skin” that detects deformations such as pressure, bending and strain. This sensor could give soft robotic systems — and anyone using augmented reality technology — the ability to feel the same rich, tactile sensations that mammals depend on to navigate the natural world.
The researchers, led by Rob Shepherd, associate professor of mechanical and aerospace engineering, are working to commercialize the technology for physical therapy and sports medicine.
Their paper, “Stretchable Distributed Fiber-Optic Sensors,” published in Science. The paper’s co-lead authors are doctoral student Hedan Bai and Shuo Li.
Bai drew inspiration from silica-based distributed fiber-optic sensors and developed a stretchable lightguide for multimodal sensing (SLIMS). This long tube contains a pair of polyurethane elastomeric cores. One core is transparent; the other is filled with absorbing dyes at multiple locations and connects to an LED. Each core is coupled with a red-green-blue sensor chip to register geometric changes in the optical path of light.
The researchers designed a 3D-printed glove with a SLIMS sensor running along each finger. The glove is powered by a lithium battery and equipped with Bluetooth so it can transmit data to basic software, which Bai designed, that reconstructs the glove’s movements and deformations in real time.

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“Right now, sensing is done mostly by vision,” Shepherd said. “We hardly ever measure touch in real life. This skin is a way to allow ourselves and machines to measure tactile interactions in a way that we now currently use the cameras in our phones. It’s using vision to measure touch. This is the most convenient and practical way to do it in a scalable way.”
Bai and Shepherd are working with Cornell’s Center for Technology Licensing to patent the technology, with an eye toward applications in physical therapy and sports medicine. Both fields have leveraged motion-tracking technology but until now have lacked the ability to capture force interactions.
The researchers are also looking into the ways SLIMS sensors can boost virtual and augmented reality experiences.
“VR and AR immersion is based on motion capture. Touch is barely there at all,” Shepherd said. “Let’s say you want to have an augmented reality simulation that teaches you how to fix your car or change a tire. If you had a glove or something that could measure pressure, as well as motion, that augmented reality visualization could say, ‘Turn and then stop, so you don’t overtighten your lug nuts.’ There’s nothing out there that does that right now, but this is an avenue to do it.”
The research was supported by the National Science Foundation (NSF); the Air Force Office of Scientific Research; Cornell Technology Acceleration and Maturation; the U.S. Department of Agriculture’s National Institute of Food and Agriculture; and the Office of Naval Research.
The researchers made use of the Cornell NanoScale Science and Technology Facility and Cornell Center for Materials Research, both of which are supported by the NSF.
Video: https://www.youtube.com/watch?v=34ucE36zSCg&feature=emb_logo

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Ecotourism offers a specific travel experience: It focuses on nature, education and sustainability. Often, these destinations highlight endangered or threatened species and engage visitors in making socially responsible choices.
But a new study by researchers at the University of Georgia suggests ecotourism’s altruistic attractions may be overshadowed by another benefit: photos for social media. Recently published in the Journal of Sustainable Tourism, the research could help guide tourism operators as they weigh the costs and benefits of attracting visitors who care most for natural beauty only when it can be captured on their phone.
“It’s been traditionally presumed that people are pursuing ecotourism because they are interested in making an environmentally or socially responsible choice — and this understanding is important for a host of reasons, including management and market segmentation,” said Justin Beall, the study’s lead author. “But our study throws a wrench in that a bit by showing that not only is it environmental values that are influencing people to participate in ecotourism, but people are also engaging in ecotourism so they can get good photographs to post online and present to their friends and loved ones.”
Beall, a recent graduate of the UGA Warnell School of Forestry and Natural Resources, wrote the paper as part of his master’s thesis. Co-authors included Warnell faculty members Bynum Boley and Kyle Woosnam, as well as UGA alumnus Adam Landon, now with the Minnesota Department of Natural Resources.
Social status over sustainability
Say, for example, someone visits an ecotourism destination and shares photos and descriptions on social media. They are conveying an image of someone who cares about sustainability, the local community and education — all components of ecotourism. But, Beall said, travelers surveyed for the study revealed that how these photos look may be even more important than their own environmental values.

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“People have a tendency to do something that elevates their status — I think we all kind of do it. This idea is not new,” added Boley. “It used to be a Porsche or a wristwatch or jewelry, but now it’s a little more subtle, and channeled through travel experiences.
“So, our big debate is, do people choose ecotourism because they have strong environmental values, or is it a new way to show off to your peers that you’re cool?”
Earlier research has suggested that ecotourists have motivations beyond environmental and social values. But with the rise of smartphones and social media, factors such as self-development, relaxation or escape are taking a back seat to the potential for likes and clicks. Boley has underscored this in more recent studies, showing how social media is changing how we view and experience travel.
Now, with this latest study, it appears the influence of social media has also reached ecotourism.
Overcrowding
While the travel industry is reeling from COVID-19, visitors to remote, natural-focused destinations are up in the U.S. On the one hand, this research presents an opportunity for the ecotourism industry to market itself by highlighting scenic opportunities to potential travelers.
But then there are problems of overcrowding to consider. Too many tourists can also be a bad thing — especially when they’re visiting sensitive natural areas. The problem is compounded for ecotourism destinations, where a small staff typically manages a larger and more fragile area. For example, visitors may stray off the established trail for their own set of photos, wandering into sensitive areas.
For years, ecotourists were categorized as a highly desirable segment of the tourism market. They have money to spend, they’re environmentally conscious and they are concerned about their effects on their destination. But perhaps that’s no longer true.
“What if all of a sudden you realize most of the people who showed up to your site aren’t ecotourists that care about your site, but just want to get the picture?” Beall asked. “With ecotourism done well, you can have this sort of low-volume, high-value tourism. But if you have all these other people that are getting in on it, and they’re not concerned about their environmental impacts, where their money goes or what they do, then it could threaten the destination’s sustainability.”

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Materials provided by University of Georgia. Original written by Kristen Morales. Note: Content may be edited for style and length. More

Modern communications technology, regardless of use, relies on a similar formula: devices send signals and information through data centers, towers and satellites en route to their final destination. The effectiveness of the communication relies on how well that information travels, and there are a variety of factors that can slow down that journey — geography, weather and more.
A new device created by researchers at The University of Texas at Austin can overcome challenges like bad weather to deliver more secure, reliable communications. This could aid military communications in challenging areas, improve the ability of self-driving cars to see the environment around them and speed up wireless data for potential 6G networks.
Ray Chen, professor in the Cockrell School of Engineering’s Department of Electrical and Computer Engineering and leader of the project, made a comparison to TV satellite dishes that go out or become fuzzy during poor weather. The same thing can happen with communications technology, and that’s the problem Chen wants to fix.
Chen’s device operates in an area of the light spectrum — mid infrared — that allows signal to penetrate through clouds, rain and other weather to get to their intended target without shedding significant amounts of light.
“Low light loss means signal can travel further, and through the earth’s atmosphere, with better integrity and less power consumption,” Chen said.
Chen’s findings were recently published in the journal Optica.

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weather proof communicationsweather proof chip The device is an indium phosphide chip capable of beam steering, the act of re-directing light in the direction of a specific target. The concept allows signal to be transmitted more accurately than other methods, reducing interference and saving power.
However, beam steering has its weaknesses that hold back mass adoption; namely that devices can only bounce light in narrow directions. Chen compares it with a person with poor peripheral vision.
However, Chen’s device features much wider angles for steering light, increasing the range by about 30 degrees compared to the other options, without moving parts or side lobes of light that trail off in various directions and decrease efficiency.
“For beam steering to be safe, you want to have a full view, you don’t want to have a bunch of blind spots,” Chen said.
A lot of self-driving cars are equipped with Light Detection and Ranging (LIDAR) technology that can sense the environment around it. Typically, these take the form of large devices attached to the top of cars with spinning arrays.

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The LIDAR devices have to spin because of the limited field of vision, Chen said. And any time you rely on a moving part, there is a risk of it breaking. The chip Chen created doesn’t require moving parts because of its wider field of vision. And fewer blind spots in the technology increases safety in situations where momentary lapses can prove dangerous.
The chips can be integrated into everything from military vehicles, to satellites, to skyscrapers. Chen is working on infusing artificial intelligence into the device for environmental sensing. The mid infrared is a part of the light spectrum that humans can’t see without aids like night vision goggles, but devices in that range can pick up things like gas leaks and smoke stack emissions.
In big cities, where it’s not practical to dig deeply underground to lay fiber cables, these devices can increase internet speeds. Putting them atop skyscrapers can enable free-space optical communication, a technology that allows wireless data to travel through the air using light.
Chen’s next big step in the project involves field-testing the device and refining its packaging to enable its application in free-space optical communications.
Funding for the project came from the Office of Naval Research and the Air Force Research Laboratory. More

Bristol scientists have demonstrated a new virtual reality [VR] technique which should help in developing drugs against the SARS-CoV-2 virus — and enable researchers to share models and collaborate in new ways. The innovative tool, created by University of Bristol researchers, and published in the Journal of Chemical Information and Modeling, will help scientists around the world identify anti-viral drug leads more rapidly.
A SARS-CoV-2 enzyme known as the main protease (Mpro) is a promising target in the search for new anti-viral treatments. Molecules that stop the main protease from working — called enzyme inhibitors — stop the virus reproducing, and so could be effective drugs. Researchers across the world are working to find such molecules. A key predictor of a drug’s effectiveness is how tightly it binds to its target; knowing how a drug fits into the protein helps researchers design changes to its structure to make it bind more tightly.
Professor Adrian Mulholland from Bristol’s School of Chemistry and the study’s lead author explained: “We’ve shown that interactive virtual reality can model how viral proteins and inhibitors bind to the enzyme. Researchers can use this tool to help understand how the enzyme works, and also to see how potential drugs fit into the enzyme. This should help design and test new potential drug leads. We are sharing these models with the whole community.”
The Bristol team have developed a virtual framework for interactive ‘molecular dynamics’ simulations. It is an open source software framework, called Narupa, which uses readily available VR equipment.
In this study, the Bristol team created a 3D model structure of the SARS-CoV-2 Mpro and used interactive molecular dynamics simulations in VR (iMD-VR) to ‘step inside’ it and visualise molecules binding to the enzyme, in atomic detail. Results showed that users were able to show how a drug molecule fits within the enzyme.
Professor Mulholland added: “There are currently many efforts globally aimed at identifying drug leads for COVID-19. Our iMD-VR tools will be a valuable resource, enabling virtual collaboration for the international drug discovery community, helping to predict how potential drug leads bind to SARS-CoV-2 targets. An exciting aspect is that it also allows researchers to collaborate in new ways: using cloud computing, they can tackle a drug discovery problem together at the same time when in they are in different locations — potentially even in different countries — working simultaneously in the same virtual molecular environment.”
“Computational modelling of how drugs bind to the SARS-CoV-2 spike protein has been critical in advancing the global fight against the pandemic. Narupa takes that modelling to an entirely new level with molecular dynamics simulations in virtual reality,” said Alison Derbenwick Miller, Vice President, Oracle for Research. “We are delighted that Oracle’s high-performance cloud infrastructure supported the development of this innovative framework, and is now helping to advance globally-connected efforts to defeat COVID-19. Growing a connected community of cloud-powered researchers is exactly what Oracle for Research was designed to do.”
The study was supported by grants from the EPSRC, the Royal Society and the British Society for Antimicrobial Chemotherapy. Cloud credits were provided by Oracle for Research.

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A new study outlines ways colleges and universities can update their curricula to prepare the workforce for a new wave of quantum technology jobs. Three researchers, including Rochester Institute of Technology Associate Professor Ben Zwickl, suggested steps that need to be taken in a new paper in Physical Review Physics Education Research after interviewing managers at more than 20 quantum technology companies across the U.S.
The study’s authors from University of Colorado Boulder and RIT set out to better understand the types of entry-level positions that exist in these companies and the educational pathways that might lead into those jobs. They found that while the companies still seek employees with traditional STEM degrees, they want the candidates to have a grasp of fundamental concepts in quantum information science and technology.
“For a lot of those roles, there’s this idea of being ‘quantum aware’ that’s highly desirable,” said Zwickl, a member of RIT’s Future Photon Initiative and Center for Advancing STEM Teaching, Learning and Evaluation. “The companies told us that many positions don’t need to have deep expertise, but students could really benefit from a one- or two-semester introductory sequence that teaches the foundational concepts, some of the hardware implementations, how the algorithms work, what a qubit is, and things like that. Then a graduate can bring in all the strength of a traditional STEM degree but can speak the language that the company is talking about.”
The authors said colleges and universities should offer introductory, multidisciplinary courses with few prerequisites that will allow software engineering, computer science, physics, and other STEM majors to learn the core concepts together. Zwickl said providing quantum education opportunities to students across disciplines will be important because quantum technology has the opportunity to disrupt a wide range of fields.
“It’s a growing industry that will produce new sensors, imaging, communication, computing technologies, and more,” said Zwickl. “A lot of the technologies are in a research and development phase, but as they start to move toward commercialization and mass production, you will have end-users who are trying to figure out how to apply the technology. They will need technical people on their end that are fluent enough with the ideas that they can make use of it.”
Zwickl’s participation in the project was supported in part by funding RIT received from the NSF’s Quantum Leap Challenge Institutes program. As a co-PI and lead on the education and workforce development for the proposal, he said he is hoping to apply many of the lessons learned from the study to RIT’s curriculum. He is in the process of developing two new introductory RIT courses in quantum information and science as well as an interdisciplinary minor in the field.

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Materials provided by Rochester Institute of Technology. Original written by Luke Auburn. Note: Content may be edited for style and length. More