Analysis of Neanderthal teeth grooves uncovers evidence of prehistoric dentistry

Date: June 28, 2017

Source: University of Kansas

Summary:

A discovery of multiple toothpick grooves on teeth and signs of other manipulations by a Neanderthal of 130,000 years ago are evidence of a kind of prehistoric dentistry, according to a new study researcher.

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                 Three views of the four articulated teeth making up KDP 20. a. occlusal view showing lingually placed mesial interproximal wear facet on P4 (arrow) and buccal wear on M3; b. lingual view showing a mesially placed interproximal wear facet on P4 (arrow), chips from lingual faces of all teeth and rotated, partially impacted M3; c. buccal view showing rotated buccal face of M3 (arrow) and hypercementosis on its root.

Credit: David Frayer, University of Kansas

Neanderthals treating toothaches?

              A discovery of multiple toothpick grooves on teeth and signs of other manipulations by a Neanderthal of 130,000 years ago are evidence of a kind of prehistoric dentistry, according to a new study led by a University of Kansas researcher.
"As a package, this fits together as a dental problem that the Neanderthal was having and was trying to presumably treat itself, with the toothpick grooves, the breaks and also with the scratches on the premolar," said David Frayer, professor emeritus of Anthropology. "It was an interesting connection or collection of phenomena that fit together in a way that we would expect a modern human to do. Everybody has had dental pain, and they know what it's like to have a problem with an impacted tooth."
                The Bulletin of the International Association for Paleodontology recently published the study. The researchers analyzed four isolated but associated mandibular teeth on the left side of the Neanderthal's mouth. Frayer's co-authors are Joseph Gatti, a Lawrence dentist, Janet Monge, of the University of Pennsylvania; and, Davorka Radovčić, curator at the Croatian Natural History Museum.
The teeth were found at Krapina site in Croatia, and Frayer and Radovčić have made several discoveries about Neanderthal life there, including a widely recognized 2015 study published in PLOS ONE about a set of eagle talons that included cut marks and were fashioned into a piece of jewelry.
The teeth and all the Krapina Neanderthal fossils were discovered more than 100 years ago from the site, which was originally excavated between 1899-1905.
                    However, Frayer and Radovčić in recent years have reexamined many items collected from the site.
In this case, they analyzed the teeth with a light microscope to document occlusal wear, toothpick groove formation, dentin scratches, and ante mortem, lingual enamel fractures.
Even though the teeth were isolated, previous researchers were able to reconstruct their order and location in the male or female Neanderthal's mouth. Frayer said researchers have not recovered the mandible to look for evidence of periodontal disease, but the scratches and grooves on the teeth indicate they were likely causing irritation and discomfort for some time for this individual.
They found the premolar and M3 molar were pushed out of their normal positions. Associated with that, they found six toothpick grooves among those two teeth and the two molars further behind them.
                  "The scratches indicate this individual was pushing something into his or her mouth to get at that twisted premolar," Frayer said.
The features of the premolar and third molar are associated with several kinds of dental manipulations, he said. Mostly because the chips of the teeth were on the tongue side of the teeth and at different angles, the researchers ruled out that something happened to the teeth after the Neanderthal died.
Past research in the fossil record has identified toothpick grooves going back almost 2 million years, Frayer said. They did not identify what the Neanderthal would have used to produce the toothpick grooves, but it possibly could have been a bone or stem of grass.
"It's maybe not surprising that a Neanderthal did this, but as far as I know, there's no specimen that combines all of this together into a pattern that would indicate he or she was trying to presumably self-treat this eruption problem," he said.
                    The evidence from the toothpick marks and dental manipulations is also interesting in light of the discovery of the Krapina Neanderthals' ability to fashion eagle talons fashioned into jewelry because people often think of Neanderthals as having "subhuman" abilities.
"It fits into a pattern of a Neanderthal being able to modify its personal environment by using tools," Frayer said, "because the toothpick grooves, whether they are made by bones or grass stems or who knows what, the scratches and chips in the teeth, they show us that Neanderthals were doing something inside their mouths to treat the dental irritation. Or at least this one was."

Cocoa and chocolate are not just treats -- they are good for your cognition

Cocoa can be seen as a dietary supplement to protect human cognition and can counteract different types of cognitive decline.

Date: June 29, 2017

Source: Frontiers

Summary:

Researchers have examined the available literature for the effects of acute and chronic administration of cocoa flavanols on different cognitive domains. It turns out that cognitive performance was improved by a daily intake of cocoa flavanols.

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Dark chocolate.

Credit: © fortyforks / Fotolia

          A balanced diet is chocolate in both hands -- a phrase commonly used to justify ones chocolate snacking behavior. A phrase now shown to actually harbor some truth, as the cocoa bean is a rich source of flavanols: a class of natural compounds that has neuroprotective effects.

In their recent review published in Frontiers in Nutrition, Italian researchers examined the available literature for the effects of acute and chronic administration of cocoa flavanols on different cognitive domains. In other words: what happens to your brain up to a few hours after you eat cocoa flavanols, and what happens when you sustain such a cocoa flavanol enriched diet for a prolonged period of time?
             Although randomized controlled trials investigating the acute effect of cocoa flavanols are sparse, most of them point towards a beneficial effect on cognitive performance. Participants showed, among others, enhancements in working memory performance and improved visual information processing after having had cocoa flavanols. And for women, eating cocoa after a night of total sleep deprivation actually counteracted the cognitive impairment (i.e. less accuracy in performing tasks) that such a night brings about. Promising results for people that suffer from chronic sleep deprivation or work shifts.
It has to be noted though, that the effects depended on the length and mental load of the used cognitive tests to measure the effect of acute cocoa consumption. In young and healthy adults, for example, a high demanding cognitive test was required to uncover the subtle immediate behavioral effects that cocoa flavanols have on this group.
             The effects of relatively long-term ingestion of cocoa flavanols (ranging from 5 days up to 3 months) has generally been investigated in elderly individuals. It turns out that for them cognitive performance was improved by a daily intake of cocoa flavanols. Factors such as attention, processing speed, working memory, and verbal fluency were greatly affected. These effects were, however, most pronounced in older adults with a starting memory decline or other mild cognitive impairments.
And this was exactly the most unexpected and promising result according to authors Valentina Socci and Michele Ferrara from the University of L'Aquila in Italy. "This result suggests the potential of cocoa flavanols to protect cognition in vulnerable populations over time by improving cognitive performance. If you look at the underlying mechanism, the cocoa flavanols have beneficial effects for cardiovascular health and can increase cerebral blood volume in the dentate gyrus of the hippocampus. This structure is particularly affected by aging and therefore the potential source of age-related memory decline in humans."
            So should cocoa become a dietary supplement to improve our cognition? "Regular intake of cocoa and chocolate could indeed provide beneficial effects on cognitive functioning over time. There are, however, potential side effects of eating cocoa and chocolate. Those are generally linked to the caloric value of chocolate, some inherent chemical compounds of the cocoa plant such as caffeine and theobromine, and a variety of additives we add to chocolate such as sugar or milk."
Nonetheless, the scientists are the first to put their results into practice: "Dark chocolate is a rich source of flavanols. So we always eat some dark chocolate. Every day."

Exposure to neonic pesticides results in early death for honeybee workers and queens

Date: June 29, 2017

Source: York University

Summary:

Worker and queen honeybees exposed to field realistic levels of neonicotinoids die sooner, reducing the health of the entire colony, biologists have found. The researchers were also surprised to find that the neonicotinoid contaminated pollen collected by the honeybees came not from crops grown from neonicotinoid treated seeds, but plants growing in areas adjacent to those crops. This is season-long, field realistic research with typical exposure.

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A worker honeybee has been fitted with a RFID on its back so researchers can record when it enters and leaves the colony.

Credit: York University Professor Amro Zayed

          Worker and queen honeybees exposed to field realistic levels of neonicotinoids die sooner, reducing the health of the entire colony, a new study led by York University biologists has found.

The researchers were also surprised to find that the neonicotinoid contaminated pollen collected by the honeybees came not from crops grown from neonicotinoid treated seeds, but plants growing in areas adjacent to those crops.
The role of neonicotinoid insecticides in honeybee colony deaths in Ontario and other parts of North America has been controversial. Some critics dismissed studies that found negative effects on worker behavior and colony health as unrealistic, suggesting bees were exposed to higher doses of pesticides for much longer than realistically found in the field.
            "This debate about field realistic exposure has been going on for a long time," said York U biology Professor Amro Zayed of the Faculty of Science. "We needed season-long monitoring of neonics in bee colonies to determine the typical exposure scenarios that occur in the field, which we have now done.
The research team studied honey bee colonies in five apiaries close to corn grown from neonicotinoid-treated seeds and six apiaries that were far from agriculture. These colonies were extensively sampled and tested for pesticides from early May to September.
"Honeybee colonies near corn were exposed to neonicotinoids for three to four months. That is most of the active bee season in temperate North America," said York U PhD student Nadia Tsvetkov.
However, the neonicotinoid contaminated pollen the honeybees collected did not belong to corn or soybean plants -- the two primary crops grown from neonicotinoid treated seeds in Ontario and Quebec.
"This indicates that neonicotinoids, which are water soluble, spill over from agricultural fields into the surrounding environment, where they are taken up by other plants that are very attractive to bees," said Tsvetkov.
          The researchers then chronically fed colonies with an artificial pollen supplement containing progressively smaller amounts of the most commonly used neonicotinoid in Ontario, clothianidin, over a 12-week period. The experiment mimicked what would occur naturally in the field.
The worker bees exposed to the treated pollen during the first nine days of life had their lifespans cut short by 23 per cent. Colonies that were exposed to treated pollen were unable to maintain a healthy laying queen, and had poor hygiene. "We found that realistic exposure to neonicotinoids near corn fields reduces the health of honey bee colonies," said Tsvetkov.
         While chronic exposure to neonicotinoids has negative effects on honeybees, the researchers also discovered that a commonly used fungicide can interact with neonicotinoids to make them more dangerous.
"The effect of neonicotinoids on honey bees quickly turns from bad to worse when you add the fungicide boscalid to the mix," said Professor Valérie Fournier of Laval University who collaborated with the York U team. "The researchers found that field realistic levels of boscalid can make neonicotinoids twice as toxic to honeybees."

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Ancient South Carolina whale yields secrets to filter feeding's origins

Date: June 29, 2017

Source: Cell Press

Summary:

The blue whale is the largest animal that has ever lived. And yet they feed almost exclusively on tiny crustaceans known as krill. The secret is in the baleen, a complex filter-feeding system that allows the enormous whales to strain huge volumes of saltwater, leaving only krill and other small organisms behind. Now, researchers who have described an extinct relative of baleen whales offer new insight into how baleen first evolved.

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This photograph shows Coronodon havensteini teeth.

Credit: Geisler et al.

             The blue whale is the largest animal that has ever lived. And yet they feed almost exclusively on tiny crustaceans known as krill. The secret is in the baleen, a complex filter-feeding system that allows the enormous whales to strain huge volumes of saltwater, leaving only krill and other small organisms behind. Now, researchers who have described an extinct relative of baleen whales in Current Biology on June 29 offer new insight into how baleen first evolved.

The findings shed light on a long-standing debate about whether the first baleen whales were toothless suction feeders or toothed whales that used their teeth like a sieve to filter prey out of water, the researchers say. The teeth of the newly discovered species of mysticete, called Coronodon havensteini, lend support to the latter view.
            "We know from the fossil record that the ancestors of baleen whales had teeth," says Jonathan Geisler of the New York Institute of Technology College of Osteopathic Medicine. "However, the transition from teeth to baleen is controversial. Our study indicates that early toothed whales used spaces between their large complex teeth for filtering and that baleen gradually replaced teeth over millions of years."
The new whale species was found in the early 2000s by a scuba diver in South Carolina's Wando River. He was looking for shark teeth and found the fossilized whale instead. The whale, which lived some 30 million years ago, was later recognized as a representative of a new transitional species.
              "The skull of this species indicates that it split off very early in mysticete whale evolution, and our analyses confirm that evolutionary position," Geisler says.
Geisler and his colleagues realized that meant the whale could offer important clues about the teeth to baleen transition. The whale under study also had other interesting features. It was larger than other toothed mysticetes, with a skull nearly one meter long. Its large molars in comparison to other whales further suggested an unusual feeding behavior.
Closer examination of the shape and wear on the whale's teeth led the researchers to conclude that the whale used its front teeth to snag prey. But the whale's large, back molars were used in filter feeding, by expelling water through open slots between the closed teeth.
             "The wear on the molars of this specimen indicates they were not used for shearing food or for biting off chunks of prey," he says. "It took us quite some time to come to the realization that these large teeth were framing narrow slots for filter feeding."
As confirmation, the researchers found wear on the hidden cusps bordering those slots between the teeth.
The findings offer another example of a broader evolutionary pattern in which body parts (in this case teeth) that evolved for one function are later co-opted for another function. The researchers say they are now examining closely related species from the Charleston, SC, area in search of additional evidence.

Graphene and terahertz waves could lead the way to future communication

Date: June 27, 2017

Source: Chalmers University of Technology

Summary:

By utilizing terahertz waves in electronics, future data traffic can get a big boost forward. So far, the terahertz (THz) frequency has not been optimally applied to data transmission, but by using graphene, researchers have come one step closer to a possible paradigm shift for the electronic industry.

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           Micrograph of the fabricated mixer circuit. The sandglass shaped 40 ?m wide graphene field-effect transistor, seen in the middle of the image, could be a key component in future high-speed wireless communication links.

Credit: Michael A. Andersson, Yaxin Zhang and Jan Stake/Chalmers University of Technology

            By utilizing terahertz waves in electronics, future data traffic can get a big boost forward. So far, the terahertz (THz) frequency has not been optimally applied to data transmission, but by using graphene, researchers at Chalmers University of Technology have come one step closer to a possible paradigm shift for the electronic industry.

           Over 60 young researchers from all over the world will learn more about this and other topics as they gather in outside of Gothenburg, Sweden, to participate in this week's summer school Graphene Study, arranged by Graphene Flagship.
It is the EU's largest ever research initiative, the Graphene Flagship, coordinated by Chalmers, who organises the school this week, 25-30 June 2017. This year it is held in Sweden with focus on electronic applications of the two-dimensional material with the extraordinary electrical, optical, mechanical and thermal properties that make it a more efficient choice than silicon in electronic applications. Andrei Vorobiev is a researcher at the Department of Micro Technology and Nanoscience at Chalmers as well as one of the many leading experts giving lectures at Graphene Study and he explains why graphene is suitable for developing devices operating in the THz range:
          "One of the graphene's special features is that the electrons move much faster than in most semiconductors used today. Thanks to this we can access the high frequencies (100-1000 times higher than gigahertz) that constitutes the terahertz range. Data communication then has the potential of becoming up to ten times faster and can transmit much larger amounts of data than is currently possible," says Andrei Vorobiev, senior researcher at Chalmers University of Technology.
Researchers at Chalmers are the first to have shown that graphene based transistor devices could receive and convert terahertz waves, a wavelength located between microwaves and infrared light, and the results were published in the journal IEEE Transactions on Microwave Theory and Techniques. One example of these devices is a 200-GHz subharmonic resistive mixer based on a CVD graphene transistor integrated on silicon that could be used in high-speed wireless communication links.
            Another example, taking advantage of graphene's unique combination of flexibility and high carrier velocity, is a power detector based on a graphene transistor integrated on flexible polymer substrates. Interesting applications for such a power detector include wearable THz sensors for healthcare and flexible THz detector arrays for high resolution interferometric imaging to be used in biomedical and security imaging, remote process control, material inspection and profiling and packaging inspection.
         "Analysis show that flexible imaging detector arrays is an area where THz applications of graphene has a very high impact potential. One example of where this could be used is in the security scanning at airports. Because the graphene-based terahertz scanner is bendable you'll get a much better resolution and can retrieve more information than if the scanner's surface is flat," says Vorobiev.
But despite the progress, much work remains before the final electronic products reach the market. Andrei Vorobiev and his colleagues are now working to replace the silicon base on which the graphene is mounted, which limits the performance of the graphene, with other two-dimensional materials which, on the contrary, can further enhance the effect. And Vorobiev hopes that he will be able to inspire the students participating in        Graphene Study to reach new scientific breakthroughs.
"In the last fifty years, all electronic development has followed Moore's law, which says that every year more and more functions will being applied on ever smaller surfaces. Now it seems that we have reached the physical limit of how small the electronic circuits can become and we need to find another principle for development. New materials can be one solution and research on graphene is showing positive results. Working with graphene-related research is about breaking new ground which involves many difficult challenges, but eventually our work can revolutionise the future of communication and that's what makes it so exciting," says Andrei Vorobiev, senior researcher at Chalmers University of Technology.

Remains of early, permanent human settlement in Andes discovered

Date: June 28, 2017

Source: University of Wyoming

Summary:

Examining human remains and other archaeological evidence from a site at nearly 12,500 feet above sea level in Peru, the scientists show that intrepid hunter-gatherers -- men, women and children -- managed to survive at high elevation before the advent of agriculture, in spite of lack of oxygen, frigid temperatures and exposure to elements.

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Intrepid hunter-gatherer families permanently occupied high-elevation environments of the Andes Mountains at least 7,000 years ago, according to new research led by University of Wyoming scientists.

Credit: Lauren A. Hayes

             Using five different scientific approaches, a team including University of Wyoming researchers has given considerable support to the idea that humans lived year-round in the Andean highlands of South America over 7,000 years ago.

Examining human remains and other archaeological evidence from a site at nearly 12,500 feet above sea level in Peru, the scientists show that intrepid hunter-gatherers -- men, women and children -- managed to survive at high elevation before the advent of agriculture, in spite of lack of oxygen, frigid temperatures and exposure to elements.
            "This gives us a very strong baseline to help understand the rates of cultural and genetic change in the Andean highlands, a region known for the domestication of alpaca, potatoes and other plants; emergence of state-level political and economic complexity; and rapid human adaptation to high-elevation life," says Randy Haas, a postdoctoral research associate in the University of Wyoming's Department of Anthropology and the team's leader.
          The research appears in the July issue of Royal Society Open Science, a peer-reviewed, open-access scientific journal. Along with Haas, the second author is Ioana Stefenescu, graduate student in UW's Department of Geology and Geophysics. Also contributing to the paper were Alexander Garcia-Putnam, doctoral student in the UW Department of Anthropology; Mark Clementz, associate professor in the Department of Geology and Geophysics; Melissa Murphy, associate professor in the Department of Anthropology; and researchers from the University of California-Davis, the University of California-Merced, the University of Arizona and Peruvian institutions.
           Excavations led by Haas at the site in southern Peru produced the remains of 16 people, along with more than 80,000 artifacts, dating to as early as 8,000 years ago. Evidence from that site, as well as others, has led some researchers to estimate that hunter-gatherers began living in the Andes around 9,000 years ago, but debate has continued over whether that human presence was permanent or seasonal.
The research team led by Haas took five different approaches to test whether there was early permanent use of the region: studying the human bones for oxygen and carbon isotopes; the travel distances from the site to low-elevation zones; the demographic mixture of the human remains; and the types of tools and other materials found with them.
              The scientists found low oxygen and high carbon isotope values in the bones, revealing the distinct signature of permanent high-elevation occupation; that travel distances to low-elevation zones were too long for seasonal human migration; that the presence of women and small children meant such migration was highly unlikely; and that almost all of the tools used by the hunter-gatherers were made with high-elevation stone material, not brought from elsewhere.
"These results constitute the strongest evidence to date that people were living year-round in the Andean highlands at least 7,000 years ago," Haas says. "Such high-elevation environments were among the last frontiers of human colonization, and this knowledge holds implications for understanding rates of genetic, physiological and cultural adaption in the human species."

Sensitive faces helped dinosaurs eat, woo and take temperature

Date: June 27, 2017

Source: University of Southampton

Summary:

Dinosaurs' faces might have been much more sensitive than previously thought, and crucial to tasks from precision eating and testing nest temperature to combat and mating rituals, according to a study.

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Artist's impression of Neovenator salerii with scan of neurovascular network superimposed.

Credit: Barker et al/Darren Naish

          Dinosaurs' faces might have been much more sensitive than previously thought, according to a University of Southampton study -- helping them with everything from picking flesh from bones to wooing potential mates.

Experts used advanced X-ray and 3D imaging techniques at the University's μ-VIS X-Ray Imaging Centre to look inside the fossilised skull of Neovenator salerii -- a large carnivorous land-based dinosaur found on the Isle of Wight -- and found evidence that it possessed an extremely sensitive snout of a kind previously only associated with aquatic feeders.
           The blood vessels and nerves that supply the head are poorly documented in dinosaur fossils, but the new study published in online journal Scientific Reports shows that Neovenator may have possessed pressure receptors in the skin of its snout -- similar to those which allow crocodiles to forage in murky water.
However, nothing about the 125-million-year-old dinosaur suggests it was an aquatic feeder, so researchers believe it must have developed such a sensitive snout for other purposes.
University of Southampton graduate Chris Barker, who was studying for his Masters degree in Vertebrate Palaeontology when he carried out the research, said: "The 3D picture we built up of the inside of Neovenator's skull was more detailed than any of us could have hoped for, revealing the most complete dinosaur neurovascular canal that we know of.
          "The canal is highly branched nearest the tip of the snout. This would have housed branches of the large trigeminal nerve -- which is responsible for sensation in the face -- and associated blood vessels. This suggests that Neovenator had an extremely sensitive snout -- a very useful adaptation, as dinosaurs used their heads for most activities."
As well as being sensitive to touch, Neovenator might also have been able to receive information relating to stimuli such as pressure and temperature, which would have come in useful for many activities -- from stroking each other's faces during courtship rituals to precision feeding.
Images of the wear pattern on the dinosaur's teeth appear to show that it actively avoided bone while removing flesh from bones.
         Chris added: "Some modern-day species, such as crocodilians and megapode birds, use their snout to measure nest temperature, and in the case of crocodiles even pick up their young with extreme care, despite their huge mouths. Neovenator might well have done the same.
"Having such a sensitive snout could have had a social use too. Many birds -- which are the descendants of dinosaurs -- use their beaks in social display, and there is plenty of evidence that carnivorous dinosaurs engaged in face-biting among themselves, perhaps targeting the sensitivity of the face to make a point."
Elis Newham, a University of Southampton PhD researcher who was also involved in the study, commented: "This finding comes at an exciting time in palaeontology, where we are using state-of-the-art technology to shed new light on the physiologies of extinct animals.
         "Our results add a new level of detail to our understanding of the way large predatory dinosaurs interacted with the world around them. The range of exciting possibilities for such facial sensitivity show just how far we have come in our re-assessment of dinosaurs from lumbering beasts to complex, highly adapted organisms."

Astronomers detect orbital motion in pair of supermassive black holes

VLBA reveals first-ever black-hole 'visual binary'

Date: June 27, 2017

Source: National Radio Astronomy Observatory

Summary:

Images made with the continent-wide Very Long Baseline Array detect the orbital motion of two supermassive black holes as they circle each other at the center of a distant galaxy. The two black holes themselves may eventually merge in an event that would produce gravitational waves that ripple across the universe.

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Artist's conception of the pair of supermassive black holes at the center of the galaxy 0402+379, 750 million light-years from Earth.

Credit: Josh Valenzuela/University of New Mexico

            Using the supersharp radio "vision" of the National Science Foundation's Very Long Baseline Array (VLBA), astronomers have made the first detection of orbital motion in a pair of supermassive black holes in a galaxy some 750 million light-years from Earth.

The two black holes, with a combined mass 15 billion times that of the Sun, are likely separated by only about 24 light-years, extremely close for such a system.
"This is the first pair of black holes to be seen as separate objects that are moving with respect to each other, and thus makes this the first black-hole 'visual binary,'" said Greg Taylor, of the University of New Mexico (UNM).
           Supermassive black holes, with millions or billions of times the mass of the Sun, reside at the cores of most galaxies. The presence of two such monsters at the center of a single galaxy means that the galaxy merged with another some time in the past. In such cases, the two black holes themselves may eventually merge in an event that would produce gravitational waves that ripple across the universe.
"We believe that the two supermassive black holes in this galaxy will merge," said Karishma Bansal, a graduate student at UNM, adding that the merger will come at least millions of years in the future.
The galaxy, an elliptical galaxy called 0402+379, after its location in the sky, was first observed in 1995. It was studied in 2003 and 2005 with the VLBA. Based on finding two cores in the galaxy, instead of one,     Taylor and his collaborators concluded in 2006 that it contained a pair of supermassive black holes.
            The latest research, which Taylor and his colleagues are reporting in the Astrophysical Journal, incorporates new VLBA observations from 2009 and 2015, along with re-analysis of the earlier VLBA data. This work revealed motion of the two cores, confirming that the two black holes are orbiting each other. The scientists' initial calculations indicate that they complete a single orbit in about 30,000 years.
"We need to continue observing this galaxy to improve our understanding of the orbit, and of the masses of the black holes," Taylor said. "This pair of black holes offers us our first chance to study how such systems interact," he added.
           The astronomers also hope to discover other such systems. The galaxy mergers that bring two supermassive black holes close together are considered to be a common process in the universe, so astronomers expect that such binary pairs should be common.
"Now that we've been able to measure orbital motion in one such pair, we're encouraged to seek other, similar pairs. We may find others that are easier to study," Bansal said.
The VLBA, part of the Long Baseline Observatory, is a continent-wide radio telescope system using ten, 240-ton dish antennas distributed from Hawaii to St. Croix in the Caribbean. All ten antennas work together as a single telescope with the greatest resolving power available to astronomy. That extraordinary resolving power allows scientists to make extremely fine measurements of objects and motions in the sky, such as those done for the research on 0402+379.
The Long Baseline Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

Nickel for thought: Compound shows potential for high-temperature superconductivity

Date: June 17, 2017

Source: DOE/Argonne National Laboratory

Summary:

Researchers have identified a nickel oxide compound as an unconventional but promising candidate material for high-temperature superconductivity. The project combined crystal growth, X-ray spectroscopy and computational theory.

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              Materials scientists at Argonne National Laboratory synthesized these single crystals of a metallic trilayer nickelate compound via a high-pressure crystal growth process. A team led by John Mitchell, an Argonne Distinguished Fellow and associate director of the laboratory's Materials Science Division, describe the compound's potential as a high-temperature superconductor in the June 12 issue of Nature Physics.

Credit: Argonne National Laboratory

            A team of researchers at the U.S. Department of Energy's (DOE) Argonne National Laboratory has identified a nickel oxide compound as an unconventional but promising candidate material for high-temperature superconductivity.

The team successfully synthesized single crystals of a metallic trilayer nickelate compound, a feat the researchers believe to be a first.
           "It's poised for superconductivity in a way not found in other nickel oxides. We're very hopeful that all we have to do now is find the right electron concentration."
This nickel oxide compound does not superconduct, said John Mitchell, an Argonne Distinguished Fellow and associate director of the laboratory's Materials Science Division, who led the project, which combined crystal growth, X-ray spectroscopy, and computational theory. But, he added, "It's poised for superconductivity in a way not found in other nickel oxides. We're very hopeful that all we have to do now is find the right electron concentration."
            Mitchell and seven co-authors announced their results in this week's issue of Nature Physics.
Superconducting materials are technologically important because electricity flows through them without resistance. High-temperature superconductors could lead to faster, more efficient electronic devices, grids that can transmit power without energy loss and ultra-fast levitating trains that ride frictionless magnets instead of rails.
            Only low-temperature superconductivity seemed possible before 1986, but materials that superconduct at low temperatures are impractical because they must first be cooled to hundreds of degrees below zero. In 1986, however, discovery of high-temperature superconductivity in copper oxide compounds called cuprates engendered new technological potential for the phenomenon.
But after three decades of ensuing research, exactly how cuprate superconductivity works remains a defining problem in the field. One approach to solving this problem has been to study compounds that have similar crystal, magnetic and electronic structures to the cuprates.
           Nickel-based oxides -- nickelates -- have long been considered as potential cuprate analogs because the element sits immediately adjacent to copper in the periodic table. Thus far, Mitchell noted, "That's been an unsuccessful quest." As he and his co-authors noted in their Nature Physics paper, "None of these analogs have been superconducting, and few are even metallic."
The nickelate that the Argonne team has created is a quasi-two-dimensional trilayer compound, meaning that it consists of three layers of nickel oxide that are separated by spacer layers of praseodymium oxide.
            "Thus it looks more two-dimensional than three-dimensional, structurally and electronically," Mitchell said.
This nickelate and a compound containing lanthanum rather than praseodymium both share the quasi-two-dimensional trilayer structure. But the lanthanum analog is non-metallic and adopts a so-called "charge-stripe" phase, an electronic property that makes the material an insulator, the opposite of a superconductor.
"For some yet-unknown reason, the praseodymium system does not form these stripes," Mitchell said. "It remains metallic and so is certainly the more likely candidate for superconductivity."
Argonne is one of a few laboratories in the world where the compound could be created. The Materials Science Division's high-pressure optical-image floating zone furnace has special capabilities. It can attain pressures of 150 atmospheres (equivalent to the crushing pressures found at oceanic depths of nearly 5,000 feet) and temperatures of approximately 2,000 degrees Celsius (more than 3,600 degrees Fahrenheit), conditions needed to grow the crystals.
            "We didn't know for sure we could make these materials," said Argonne postdoctoral researcher Junjie Zhang, the first author on the study. But indeed, they managed to grow the crystals measuring a few millimeters in diameter (a small fraction of an inch).
The research team verified that the electronic structure of the nickelate resembles that of cuprate materials by taking X-ray absorption spectroscopy measurements at the Advanced Photon Source, a DOE Office of Science User Facility, and by performing density functional theory calculations. Materials scientists use density functional theory to investigate the electronic properties of condensed matter systems.
"I've spent my entire career not making high-temperature superconductors," Mitchell joked. But that could change in the next phase of his team's research: attempting to induce superconductivity in their nickelate material using a chemical process called electron doping, in which impurities are deliberately added to a material to influence its properties.

To connect biology with electronics, be rigid, yet flexible

Date: June 19, 2017

Source: University of Washington

Summary:

Scientists have measured a thin film made of a single type of conjugated polymer  a conducting plastic  as it interacted with ions and electrons. They show how there are rigid and non-rigid regions of the film, and that these regions could accommodate electrons or ions  but not both equally.

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          Depiction a thin film in orange and yellow, showing regions that are able to subtly swell to let in ion molecules.

Credit: Rajiv Giridharagopal

           That conclusion might crop up during divorce proceedings, or describe a diplomatic row. But scientists designing polymers that can bridge the biological and electronic divide must also deal with incompatible messaging styles. Electronics rely on racing streams of electrons, but the same is not true for our brains.

           "Most of our technology relies on electronic currents, but biology transduces signals with ions, which are charged atoms or molecules," said David Ginger, professor of chemistry at the University of Washington and chief scientist at the UW's Clean Energy Institute. "If you want to interface electronics and biology, you need a material that effectively communicates across those two realms."
Ginger is lead author of a paper published online June 19 in Nature Materials in which UW researchers directly measured a thin film made of a single type of conjugated polymer -- a conducting plastic -- as it interacted with ions and electrons. They show how variations in the polymer layout yielded rigid and non-rigid regions of the film, and that these regions could accommodate electrons or ions -- but not both equally.  The softer, non-rigid areas were poor electron conductors but could subtly swell to take in ions, while the opposite was true for rigid regions.
            Organic semiconducting polymers are complex matrices made from repeating units of a carbon-rich molecule. An organic polymer that can accommodate both types of conduction -- ion and electrons -- is the key to creating new biosensors, flexible bioelectronic implants and better batteries. But differences in size and behavior between tiny electrons and bulky ions have made this no easy task.
Their results demonstrate how critical the polymer synthesis and layout process is to the film's electronic and ionic conductance properties. Their findings may even point the way forward in creating polymer devices that can balance the demands of electronic transport and ion transport.
           "We now understand the design principles to make polymers that can transport both ions and electrons more effectively," said Ginger. "We even demonstrate by microscopy how to see the locations in these soft polymer films where the ions are transporting effectively and where they aren't."
Ginger's team measured the physical and electrochemical properties of a film made out of poly(3-hexylthiophene), or P3HT, which is a relatively common organic semiconductor material. Lead author Rajiv Giridharagopal, a research scientist in the UW Department of Chemistry, probed the P3HT film's electrochemical properties in part by borrowing a technique originally developed to measure electrodes in lithium-ion batteries.
            The approach, electrochemical strain microscopy, uses a needle-like probe suspended by a mechanical arm to measure changes in the physical size of an object with atomic-level precision. Giridharagopal discovered that, when a P3HT film was placed in an ion solution, certain regions of the film could subtly swell to let ions flow into the film.
"This was an almost imperceptible swelling -- just 1 percent of the film's total thickness," said Giridharagopal. "And using other methods, we discovered that the regions of the film that could swell to accommodate ion entry also had a less rigid structure and polymer arrangement."
More rigid and crystalline regions of the film could not swell to let in ions. But the rigid areas were ideal patches for conducting electrons.
              Ginger and his team wanted to confirm that structural variations in the polymer were the cause of these variations in electrochemical properties of the film. Co-author Christine Luscombe, a UW associate professor of materials science and engineering and member of the Clean Energy Institute, and her team made new P3HT films that had different levels of rigidity based on variations in polymer arrangement.
By subjecting these new films to the same array of tests, Giridharagopal showed a clear correlation between polymer arrangement and electrochemical properties. The less rigid and more amorphous polymer layouts yielded films that could swell to let in ions, but were poor conductors of electrons. More crystalline polymer arrangements yielded more rigid films that could easily conduct electrons.
              These measurements demonstrate for the first time that small structural differences in how organic polymers are processed and assembled can have major consequences for how the film accommodates ions or electrons. It may also mean that this tradeoff between the needs of ion and electrons is unavoidable. But these results give Ginger hope that another solution is possible.
"The implication of these findings is that you could conceivably embed a crystalline material -- which could transport electrons -- within a material that is more amorphous and could transport ions," said Ginger. "Imagine that you could harness the best of both worlds, so that you could have a material that is able to effectively transport electrons and swell with ion uptake -- and then couple the two with one another."
If so, then a bioelectronic divorce may not be on the horizon, but better bioelectronic devices and better batteries should be.

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Catalyst mimics the z-scheme of photosynthesis

Date: June 22, 2017

Source: University of Kentucky

Summary:

A new study demonstrates a process with great potential for developing technologies for reducing CO2 levels.

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         This is the Cu2O (right) that gets photocorrosion compared to Cu2O/TiO2 (left) that operates under a Z-scheme to reduce CO2.

Credit: Ruixin Zhou, UK doctoral student of chemistry.

          A team of chemists from the University of Kentucky and the Institute of Physics Research of Mar del Plata in Argentina has just reported a way to trigger a fundamental step in the mechanism of photosynthesis, providing a process with great potential for developing new technology to reduce carbon dioxide levels.

Led by Marcelo Guzman, an associate professor of chemistry in the UK College of Arts and Sciences, and Ruixin Zhou, a doctoral student working with Guzman, the researchers used a synthetic nanomaterial that combines the highly reducing power of cuprous oxide (Cu₂O) with a coating of oxidizing titanium dioxide (TiO₂) that prevents the loss of copper (I) ion in the catalyst. The catalyst made of Cu₂O/TiO₂ has the unique ability to transfer electrons for reducing the atmospheric greenhouse gas carbon dioxide (CO₂) while simultaneously breaking the molecule of water (H₂O). The unique feature of this catalyst for electron transfer mimics the so called "Z-scheme" mechanism from photosynthesis.
           Published in Applied Catalysis B: Environmental, the researchers demonstrated that if the catalyst is exposed to sunlight, electrons are transferred to CO₂ in a process that resembles the way photosystems 1 and 2 operate in nature.
"Developing the materials that can be combined to reduce CO₂ through a direct Z-scheme mechanism with sunlight is an important problem," said Zhou. "However, it is even more difficult to demonstrate the process actually works. From this scientific viewpoint, the research is contributing to advance feature technology for carbon sequestration."
           This is a task that many scientists have been pursuing for a long time but the challenge is to prove that both components of the catalyst interact to enable the electronic properties of a Z-scheme mechanism. Although a variety of materials may be used, the key aspect of this research is that the catalyst is not made of scarce and very expensive elements such as rhenium and iridium to drive the reactions with sunlight energy reaching the Earth's surface. The catalyst employed corrosion resistant TiO₂ to apply a white protective coating to octahedral particles of red Cu₂O.
            The team designed a series of experiments to test out the hypothesis that the catalyst operates through a Z-scheme instead of using a double-charge transfer mechanism. The measured carbon monoxide (CO) production from CO₂ reduction, the identification of hydroxyl radical (HO* ) intermediate from H₂O oxidation en route to form oxygen (O₂), and the characterized electronic and optical properties of the catalyst and individual components verified the proposed Z-scheme was operational.
The next goal of the research is to improve the approach by exploring a series of different catalysts and identify the most efficient one to transform CO₂ into chemical fuels such as methane. This way, new technology will be created to supply clean and affordable alternative energy sources and to address the problem of continuous consumption of fossil fuels and rising levels of greenhouse gases.

Bioengineers create more durable, versatile wearable for diabetes monitoring

Team refines biosensor to measure three molecules for a week

Date: June 23, 2017

Source: University of Texas at Dallas

Summary:

Researchers are getting more out of the sweat they've put into their work on a wearable diagnostic tool that measures three diabetes-related compounds in microscopic amounts of perspiration. In a study, the team describes their wearable diagnostic biosensor that can detect three interconnected compounds - cortisol, glucose and interleukin-6 - in perspired sweat for up to a week without loss of signal integrity.

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             Researchers at the University of Texas at Dallas have developed a wearable diagnostic biosensor that can detect three interconnected, diabetes-related compounds -- cortisol, glucose and interleukin-6 -- in perspired sweat for up to a week without loss of signal integrity. The team envisions that their wearable devices will contain a small transceiver to send data to an application installed on a cellphone.

Credit: University of Texas at Dallas

            Researchers at The University of Texas at Dallas are getting more out of the sweat they've put into their work on a wearable diagnostic tool that measures three diabetes-related compounds in microscopic amounts of perspiration.

"Type 2 diabetes affects so many people. If you have to manage and regulate this chronic problem, these markers are the levers that will help you do that," said Dr. Shalini Prasad, professor of bioengineering in the Erik Jonsson School of Engineering and Computer Science. "We believe we've created the first diagnostic wearable that can monitor these compounds for up to a week, which goes beyond the type of single use monitors that are on the market today."
             In a study published recently in Scientific Reports, Prasad and lead author Dr. Rujute Munje, a recent bioengineering PhD graduate, describe their wearable diagnostic biosensor that can detect three interconnected compounds -- cortisol, glucose and interleukin-6 -- in perspired sweat for up to a week without loss of signal integrity.
"If a person has chronic stress, their cortisol levels increase, and their resulting insulin resistance will gradually drive their glucose levels out of the normal range," said Prasad, Cecil H. and Ida Green Professor in Systems Biology Science. "At that point, one could become pre-diabetic, which can progress to type 2 diabetes, and so on. If that happens, your body is under a state of inflammation, and this inflammatory marker, interleukin-6, will indicate that your organs are starting to be affected."
           Last October, Prasad and her research team confirmed they could measure glucose and cortisol in sweat. Several significant advances since then have allowed them to create a more practical, versatile tool.
"We wanted to make a product more useful than something disposable after a single use," Prasad said. "It also has to require only your ambient sweat, not a huge amount. And it's not enough to detect just one thing. Measuring multiple molecules in a combinatorial manner and tracking them over time allows us to tell a story about your health."
            One factor that facilitated their device's progress was the use of room temperature ionic liquid (RTIL), a gel that serves to stabilize the microenvironment at the skin-cell surface so that a week's worth of hourly readings can be taken without the performance degrading over time.
"This greatly influences the cost model for the device -- you're buying four monitors per month instead of 30; you're looking at a year's supply of only about 50," Prasad said. "The RTIL also allows the detector to interface well with different skin types -- the texture and quality of pediatric skin versus geriatric skin have created difficulties in prior models. The RTIL's ionic characteristics make it somewhat like applying moisturizer to skin."
            Prasad's team also determined that their biomarker measurements are reliable with a tiny amount of sweat -- just 1 to 3 microliters, much less than the 25 to 50 previously believed necessary.
"We actually spent three years producing that evidence," Prasad said. "At those low volumes, the biomolecules expressed are meaningful. We can do these three measurements in a continuous manner with that little sweat."
Prasad envisions that her wearable devices will contain a small transceiver to send data to an application installed on a cellphone.
         "With the app we're creating, you'll simply push a button to request information from the device," Prasad said. "If you measure levels every hour on the hour for a full week, that provides 168 hours' worth of data on your health as it changes."
That frequency of measurement could produce an unprecedented picture of how the body responds to dietary decisions, lifestyle activities and treatment.
"People can take more control and improve their own self-care," Prasad said. "A user could learn which unhealthy decisions are more forgiven by their body than others."
           Prasad has emphasized "frugal innovation" throughout the development process, making sure the end product is accessible for as many people as possible.
"We've designed this product so that it can be manufactured using standard coating techniques. We made sure we used processes that will allow for mass production without adding cost," Prasad said. "Our cost of manufacturing will be comparable to what it currently takes to make single-use glucose test strips -- as little as 10 to 15 cents. It needs to reach people beyond America and Europe -- and even within first-world nations, we see the link between diabetes and wealth. It can't simply be a small percentage of people who can afford this."
           Prasad was motivated to address this specific problem in part by her own story.
"South Asians, like myself, are typically prone to diabetes and to cardiovascular disease," Prasad said. "If I can monitor on a day-to-day basis how my body is responding to intake, and as I age, if I can adjust my lifestyle to keep those readings where they need to be, then I can delay getting a disease, if not prevent it entirely."
            For Prasad, the latest work is a fulfilling leap forward in what has already been a five-year process.
"We've been solving this problem since 2012, in three phases," Prasad said. "The initial concept for a system level integration of these sensors was done in collaboration with EnLiSense LLC, a startup focused on enabling lifestyle based sensors and devices. In the market, there's nothing that is a slap-on wearable that uses perspired sweat for diagnostics. And I think we are the closest. If we find the right partner, then within a 12-month window, we hope to license our technology and have our first products in the market."

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Smooth propagation of spin waves using gold

The generation mechanism of spin wave noise and the suppression method

Date: June 22, 2017

Source: Toyohashi University of Technology

Summary:

A scientist has elucidated the noise generation mechanism of the spin wave (SW), the wave of a magnetic moment transmitted through magnetic oxide, and established a way to suppress it. The large noise generated by SWs traveling through magnetic oxides has presented a significant obstacle to its applications. However, it became clear that noise can be suppressed by installing a thin gold film in the appropriate places.

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           This is a magnetic oxide film treated with gold film capable of suppressing SW noise.

Credit: Copyright Toyohashi University of Technology - All Rights Reserved

               Assistant Professor Taichi Goto at Toyohashi University of Technology elucidated the noise generation mechanism of the spin wave (SW), the wave of a magnetic moment transmitted through magnetic oxide, and established a way to suppress it. The large noise generated by SWs traveling through magnetic oxides has presented a significant obstacle to its applications. However, it became clear that noise can be suppressed by installing a thin gold film in the appropriate places. This method is expected to be applied to SW devices such as multi-input and multi-output phase interference devices for SWs. The research results were reported in Journal of Physics D: Applied Physics on June 15, 2017.

Recent electronic devices using semiconductor materials are having difficulty meeting the demand of a rapidly growing information society due to issues such as a high chip temperature due to high integration.  Development of an SW logic circuit that can process information, and significantly suppress heat generation through transmitting only SWs without transferring electrons themselves, has been attracting attention. SWs that propagate through magnetic oxides have the advantage of low energy loss and a long transmission distance. On the other hand, as the loss is so small, SW reflected at the end of the material or interface with the electrode disturb the target spin wave. This phenomenon is called SW noise, which has made SW unsuitable for application in the past.
               The Spin Electronics Group of Toyohashi University of Technology discovered that forming a gold film with sufficient length at the end of an yttrium iron garnet (YIG), which is a well-known magnetic oxide material, suppresses the generation of unnecessary SWs. In addition, the group found for the first time that SW noise is also sensitive to the position of the gold film.
"There are series of new devices using SWs and findings of new phenomena, yet there hasn't been much research on finding out how to transmit SWs through magnetic oxide or elucidating the cause of the generation of disturbing SWs.," said Assistant Professor Goto.
                 The first author master course student Shimada who ran the simulation said, "We analyzed the fundamental propagation characteristics of the structure using gold film. Since this method can significantly suppress the noise, it will contribute to the development of SW devices that use magnetic oxide. Furthermore, SW logic circuits that use phase information can be realized as the phases of waves are stabilized." SW propagation characteristics were calculated and analyzed based on the finite element analysis method, by computer generating a three-dimensional model that has the same size as the sample used in the actual experiment. A model with a pair of electrodes for exciting SWs and a gold film for removing noise placed on the magnetic oxide was used to find out how gold film affects SW propagation by comprehensively changing the length of magnetic oxide materials, the position of the gold film, and the distance from the electrode. The result showed that when the distance between the gold film and the electrodes is long, a standing wave of SWs is generated, causing strong noise. The group learned that the noise can be suppressed by positioning the gold film close enough to the electrodes. This helps smoothen the propagation characteristics, and realizes a stable element design that can keep the influence of some frequency variations and disturbances to the entire device, to the propagation characteristics, small.
This simulation is a known method with high reproducibility. Therefore, the method is expected to be applied to SW devices such as multi-input/multi-output phase interference devices for SW in the future.

Atomic imperfections move quantum communication network closer to reality

Date: June 23, 2017

Source: University of Chicago

Summary:

An international team of scientists has discovered how to manipulate a weird quantum interface between light and matter in silicon carbide along wavelengths used in telecommunications.

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              Single spins in silicon carbide absorb and emit single photons based on the state of their spin.

Credit: Prof. David Awschalom

An international team led by the University of Chicago's Institute for Molecular Engineering has discovered how to manipulate a weird quantum interface between light and matter in silicon carbide along wavelengths used in telecommunications.

                The work advances the possibility of applying quantum mechanical principles to existing optical fiber networks for secure communications and geographically distributed quantum computation. Prof. David Awschalom and his 13 co-authors announced their discovery in the June 23 issue of Physical Review X.
"Silicon carbide is currently used to build a wide variety of classical electronic devices today," said Awschalom, the Liew Family Professor in Molecular Engineering at UChicago and a senior scientist at Argonne National Laboratory. "All of the processing protocols are in place to fabricate small quantum devices out of this material. These results offer a pathway for bringing quantum physics into the technological world."
                The findings are partly based on theoretical models of the materials performed by Awschalom's co-authors at the Hungarian Academy of Sciences in Budapest. Another research group in Sweden's Linköping University grew much of the silicon carbide material that Awschalom's team tested in experiments at UChicago. And another team at the National Institutes for Quantum and Radiological Science and Technology in Japan helped the UChicago researchers make quantum defects in the materials by irradiating them with electron beams.
           Quantum mechanics govern the behavior of matter at the atomic and subatomic levels in exotic and counterintuitive ways as compared to the everyday world of classical physics. The new discovery hinges on a quantum interface within atomic-scale defects in silicon carbide that generates the fragile property of entanglement, one of the strangest phenomena predicted by quantum mechanics.
Entanglement means that two particles can be so inextricably connected that the state of one particle can instantly influence the state of the other, no matter how far apart they are.
           "This non-intuitive nature of quantum mechanics might be exploited to ensure that communications between two parties are not intercepted or altered," Awschalom said.
The findings enhance the once-unexpected opportunity to create and control quantum states in materials that already have technological applications, Awschalom noted. Pursuing the scientific and technological potential of such advances will become the focus of the newly announced Chicago Quantum Exchange, which Awschalom will direct.
             An especially intriguing aspect of the new paper was that silicon carbide semiconductor defects have a natural affinity for moving information between light and spin (a magnetic property of electrons). "A key unknown has always been whether we could find a way to convert their quantum states to light," said David Christle, a postdoctoral scholar at the University of Chicago and lead author of the work. "We knew a light-matter interface should exist, but we might have been unlucky and found it to be intrinsically unsuitable for generating entanglement. We were very fortuitous in that the optical transitions and the process that converts the spin to light is of very high quality."
The defect is a missing atom that causes nearby atoms in the material to rearrange their electrons. The missing atom, or the defect itself, creates an electronic state that researchers control with a tunable infrared laser.
             "What quality basically means is: How many photons can you get before you've destroyed the quantum state of the spin?" said Abram Falk, a researcher at the IBM Thomas J. Watson Resarch Center in Yorktown Heights, N.Y., who is familiar with the work but not a co-author on the paper.
The UChicago researchers found that they could potentially generate up to 10,000 photons, or packets of light, before they destroyed the spin state. "That would be a world record in terms of what you could do with one of these types of defect states," Falk added.
Awschalom's team was able to turn the quantum state of information from single electron spins in commercial wafers of silicon carbide into light and read it out with an efficiency of approximately 95 percent.
              The duration of the spin state -- called coherence -- that Awschalom's team achieved was a millisecond. Not much by clock standards, but quite a lot in the realm of quantum states, in which multiple calculations can be carried out in a nanosecond, or a billionth of a second.
The feat opens up new possibilities in silicon carbide because its nanoscale defects are a leading platform for new technologies that seek to use quantum mechanical properties for quantum information processing, sensing magnetic and electric fields and temperature with nanoscale resolution, and secure communications using light.
            "There's about a billion-dollar industry of power electronics built on silicon carbide," Falk said. "Following this work, there's an opportunity to build a platform for quantum communication that leverages these very advanced classical devices in the semiconductor industry," he said.
Most researchers studying defects for quantum applications have focused on an atomic defect in diamond, which has become a popular visible-light testbed for these technologies.
"Diamond has been this huge industry of quantum control work," Falk noted. Dozens of research groups across the country have spent more than a decade perfecting the material to achieve standards that Awschalom's group has mastered in silicon carbide after only a few years of investigation.
              "There are many different forms of silicon carbide, and some of them are commonly used today in electronics and optoelectronics," Awschalom said. "Quantum states are present in all forms of silicon carbide that we've explored. This bodes well for introducing quantum mechanical effects into both electronic and optical technologies."
Researchers now are beginning to wonder if this type of physics also may work in other materials, Falk noted.
              "Moreover, can we rationally design a defect that has the properties we want, not just stumble into one?" he asked.
Defects are the key.
"For decades the electronics industry has come up with a myriad of tricks to remove all the defects from their devices because defects often cause problems in conventional electronics," Awschalom explained. "Ironically, we're putting the defects back in for quantum systems."

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Researchers design sounds that can be recorded by microphones but inaudible to humans

Date: June 23, 2017

Source: University of Illinois College of Engineering

Summary:

Researchers have designed a sound that is completely inaudible to humans (40 kHz or above) yet is audible to any microphone. The sound combines multiple tones that, when interacting with the microphone's mechanics, create what researchers call a 'shadow,' which is a sound that the microphones can detect.

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          The sound's frequency is designed by the researchers and transmitted from ultrasonic speakers, completely inaudible to humans but able to be recorded by microphones.

Credit: Coordinated Science Laboratory

             Microphones, from those in smartphones to hearing aids, are built specifically to hear the human voice humans can't hear at levels higher than 20 kHz, and microphones max out at around 24 kHz, meaning that microphones only capture the sound we can hear with our ears.

However, researchers at the Coordinated Science Laboratory at the University of Illinois have designed a sound that is completely inaudible to humans (40 kHz or above) yet is audible to any microphone. The sound combines multiple tones that, when interacting with the microphone's mechanics, create what researchers call a "shadow," which is a sound that the microphones can detect.
               The team, which includes PhD student Nirupam Roy and CSL Professors Romit Roy Choudhury and Haitham Hassanieh, see many applications for this work. This work won Best Paper Award, titled "BackDoor: Making Microphones Hear Inaudible Sounds," at a leading conference, MobiSys 2017.
"Imagine having a private conversation with someone. You can broadcast this inaudible signal, which translates to a white noise in the microphone, to prevent any spy microphones from recording voices," said Roy, a PhD student in electrical and computer engineering. "Because it's inaudible, it wouldn't interfere at all with the conversation."
              According to the researchers, military and government officials could secure private and confidential meetings from electronic eavesdropping or cinemas and concerts could prevent unauthorized recording of movies and live performances.
The signal can also be used to send communication between Internet of Things (IoT) devices, such as an Amazon Echo or Google Home, which would reduce the growing load on Bluetooth, since Bluetooth is primarily how IoT devices communicate. They also foresee that this signal could protect users from unauthorized recording when communicating with voice-activated systems.
             "We thought, can we design an application so that when you are actually giving a message, like to an Amazon Echo, no one can record your voice to the Amazon Echo if we're playing this sound?" said Roy. "Voice-activated systems are everywhere, so now it is important to build defenses against attacks that can be launched through your voice."
The sound's frequency is designed by the researchers and transmitted from ultrasonic speakers, completely inaudible to humans but able to be recorded by microphones.
               The sound's frequency is designed by the researchers and transmitted from ultrasonic speakers, completely inaudible to humans but able to be recorded by microphones.
The team acknowledges there may be ways to misuse this technology, though they hope that by knowing the problems that can arise, they can build measures to protect against it.
"Inaudible sound jammers, could, for example, affect someone wearing a hearing aid because the internal microphone would pick up that sound," said Roy. "Or, for example, in a bank robbery, someone might be trying to make a phone call to 911, but this sound could jam all the phones trying to make calls."
Like all techniques, inaudible sounds can be used in different ways, but "with this knowledge of how it can be used negatively, we can develop strategies to prevent it," said Roy Choudhury, an associate professor of electrical and computer engineering.
             The sound's frequency is designed by the researchers and transmitted from ultrasonic speakers, but the microphone -- the receiver of the signal -- is not altered in anyway. Off-the-shelf microphones will react in the same way to the signal.
"Microphones are in millions of devices, including all of our smartphones," said Hassanieh, an assistant professor of electrical and computer engineering. "And this signal can be received without modifying the microphone, making this technique readily available to interact with the devices around us."

2-D material's traits could send electronics R&D spinning in new directions

X-ray technique provides a new window into exotic properties of an atomically thin material

Date: June 26, 2017

Source: DOE/Lawrence Berkeley National Laboratory

Summary:

Researchers created an atomically thin material and used X-rays to measure its exotic and durable properties that make it a promising candidate for a budding branch of electronics known as 'spintronics.'

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              This is a scanning tunneling microscopy image of a 2-D material created and studied at Berkeley Lab's Advanced Light Source (orange, background). In the upper right corner, the blue dots represent the layout of tungsten atoms and the red dots represent tellurium atoms.

Credit: Berkeley Lab

            An international team of researchers, working at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and UC Berkeley, fabricated an atomically thin material and measured its exotic and durable properties that make it a promising candidate for a budding branch of electronics known as "spintronics."

            The material -- known as 1T'-WTe2 -- bridges two flourishing fields of research: that of so-called 2-D materials, which include monolayer materials such as graphene that behave in different ways than their thicker forms; and topological materials, in which electrons can zip around in predictable ways with next to no resistance and regardless of defects that would ordinarily impede their movement.
At the edges of this material, the spin of electrons -- a particle property that functions a bit like a compass needle pointing either north or south -- and their momentum are closely tied and predictable.
             This latest experimental evidence could elevate the material's use as a test subject for next-gen applications, such as a new breed of electronic devices that manipulate its spin property to carry and store data more efficiently than present-day devices. These traits are fundamental to spintronics.
The material is called a topological insulator because its interior surface does not conduct electricity, and its electrical conductivity (the flow of electrons) is restricted to its edges.
"This material should be very useful for spintronics studies," said Sung-Kwan Mo, a physicist and staff scientist at Berkeley Lab's Advanced Light Source (ALS) who co-led the study, published in Nature Physics.
            "The flow of electrons is completely linked with the direction of their spins, and is limited only to the edges of the material," Mo said. "The electrons will travel in one direction, and with one type of spin, which is a useful quality for spintronics devices." Such devices could conceivably carry data more fluidly, with lesser power demands and heat buildup than is typical for present-day electronic devices.
"We're excited about the fact that we have found another family of materials where we can both explore the physics of 2-D topological insulators and do experiments that may lead to future applications," said Zhi-Xun Shen, a professor in Physical Sciences at Stanford University and the Advisor for Science and Technology at SLAC National Accelerator Laboratory who also co-led the research effort. "This general class of materials is known to be robust and to hold up well under various experimental conditions, and these qualities should allow the field to develop faster," he added.
                 The material was fabricated and studied at the ALS, an X-ray research facility known as a synchrotron. Shujie Tang, a visiting postdoctoral researcher at Berkeley Lab and Stanford University, and a co-lead author in the study, was instrumental in growing 3-atom-thick crystalline samples of the material in a highly purified, vacuum-sealed compartment at the ALS, using a process known as molecular beam epitaxy.
The high-purity samples were then studied at the ALS using a technique known as ARPES (or angle-resolved photoemission spectroscopy), which provides a powerful probe of materials' electron properties.
"After we refined the growth recipe, we measured it with ARPES. We immediately recognized the characteristic electronic structure of a 2-D topological insulator," Tang said, based on theory and predictions. "We were the first ones to perform this type of measurement on this material."
But because the conducting part of this material, at its outermost edge, measured only a few nanometers thin  thousands of times thinner than the X-ray beam's focus -- it was difficult to positively identify all of the material's electronic properties.
               So collaborators at UC Berkeley performed additional measurements at the atomic scale using a technique known as STM, or scanning tunneling microscopy. "STM measured its edge state directly, so that was a really key contribution," Tang said.
The research effort, which began in 2015, involved more than two dozen researchers in a variety of disciplines. The research team also benefited from computational work at Berkeley Lab's National Energy Research Scientific Computing Center (NERSC).
Two-dimensional materials have unique electronic properties that are considered key to adapting them for spintronics applications, and there is a very active worldwide R&D effort focused on tailoring these materials for specific uses by selectively stacking different types.
                 "Researchers are trying to sandwich them on top of each other to tweak the material as they wish  like Lego blocks," Mo said. "Now that we have experimental proof of this material's properties, we want to stack it up with other materials to see how these properties change."
A typical problem in creating such designer materials from atomically thin layers is that materials typically have nanoscale defects that can be difficult to eliminate and that can affect their performance. But because 1T'-WTe2 is a topological insulator, its electronic properties are by nature resilient.
                   "At the nanoscale it may not be a perfect crystal," Mo said, "but the beauty of topological materials is that even when you have less than perfect crystals, the edge states survive. The imperfections don't break the key properties."
Going forward, researchers aim to develop larger samples of the material and to discover how to selectively tune and accentuate specific properties. Besides its topological properties, its "sister materials," which have similar properties and were also studied by the research team, are known to be light-sensitive and have useful properties for solar cells and for optoelectronics, which control light for use in electronic devices.