News Article | May 10, 2017
Scientists have greatly expanded the range of functional temperatures for ferroelectrics, a key material used in a variety of everyday applications, by creating the first-ever polarization gradient in a thin film. The achievement, reported May 10 in Nature Communications by researchers at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), paves the way for developing devices capable of supporting wireless communications in extreme environments, from inside nuclear reactors to Earth's polar regions. Ferroelectric materials are prized for having a spontaneous polarization that is reversible by an applied electric field and for the ability to produce electric charges in response to physical pressure. They can function as capacitors, transducers, and oscillators, and they can be found in applications such as transit cards, ultrasound imaging, and push-button ignition systems. Berkeley Lab scientists created a strain and chemical gradient in a 150-nanometer-thin film of barium strontium titanate, a widely used ferroelectric material. The researchers were able to directly measure the tiny atomic displacements in the material using cutting-edge advanced microscopy at Berkeley Lab, finding gradients in the polarization. The polarization varied from 0 to 35 microcoulombs per centimeter squared across the thickness of the thin-film material. "Traditional physics and engineering textbooks wouldn't have predicted this observation," said study principal investigator Lane Martin, faculty scientist at Berkeley Lab's Materials Sciences Division and UC Berkeley associate professor of materials and engineering. "Creating gradients in materials costs a lot of energy--Mother Nature doesn't like them--and the material works to level out such imbalances in whatever way possible. In order for a large gradient like the one we have here to occur, we needed something else in the material to compensate for this unfavorable structure. In this case, the key is the material's naturally occurring defects, such as charges and vacancies of atoms, that accommodate the imbalance and stabilize the gradient in polarization." Creating a polarization gradient had the beneficial effect of expanding the temperature range for optimal performance by the ferroelectric material. Barium titanate's function is strongly temperature-dependent with relatively small effects near room temperature and a large, sharp peak in response at around 120 degrees Celsius. This makes it hard to achieve well-controlled, reliable function as the temperature varies beyond a rather narrow window. To adapt the material to work for applications at and around room temperature, engineers tune the chemistry of the material, but the range of temperatures where the materials are useful remains relatively narrow. "The new polarization profile we have created gives rise to a nearly temperature-insensitive dielectric response, which is not common in ferroelectric materials," said Martin. "By making a gradient in the polarization, the ferroelectric simultaneously operates like a range or continuum of materials, giving us high-performance results across a 500-degree Celsius window. In comparison, standard, off-the-shelf materials today would give the same responses across a much smaller 50-degree Celsius window." Beyond the obvious expansions to hotter and colder environments, the researchers noted that this wider temperature range could shrink the number of components needed in electronic devices and potentially reduce the power draw of wireless phones. "The smartphone I'm holding in my hand right now has dielectric resonators, phase shifters, oscillators--more than 200 elements altogether--based on similar materials to what we studied in this paper," said Martin. "About 45 of those elements are needed to filter the signals coming to and from your cell phone to make sure you have a clear signal. That's a huge amount of real estate to dedicate to one function." Because changes in temperature alter the resonance of the ferroelectric materials, there are constant adjustments being made to match the materials to the wavelength of the signals sent from cell towers. Power is needed to tune the signal, and the more out of tune it is, the more power the phone needs to use to get a clear signal for the caller. A material with a polarization gradient capable operating over large temperatures regimes could reduce the power needed to tune the signal. Understanding the polarization gradient entailed the use of epitaxial strain, a strategy in which a crystalline overlayer is grown on a substrate, but with a mismatch in the lattice structure. This strain engineering technique, commonly employed in semiconductor manufacturing, helps control the structure and enhance performance in materials. Recent advances in electron microscopy have allowed researchers to obtain atomic-scale structural data of the strained barium strontium titanate, and to directly measure the strain and polarization gradient. "We have established a way to use nanobeam scanning diffraction to record diffraction patterns from each point, and afterwards analyze the datasets for strain and polarization data," said study co-author Andrew Minor, director of the National Center for Electron Microscopy at Berkeley Lab's Molecular Foundry, a DOE Office of Science User Facility. "This type of mapping, pioneered at Berkeley Lab, is both new and very powerful." Another key factor was the speed of the detector, Minor added. For this paper, data was obtained at a rate of 400 frames per second, an order of magnitude faster than the 30-frame-per-second rate from just a few years ago. This technique is now available for users at the Foundry. "We're seeing a revolution in microscopy related to the use of direct electron detectors that is changing many fields of research," said Minor, who also holds an appointment as a UC Berkeley professor of materials science and engineering. "We're able to both see and measure things at a scale that was hard to imagine until recently." Co-lead authors of the study are postdoctoral researcher Anoop Damodaran and graduate student Shishir Pandya at UC Berkeley's Department of Materials Science and Engineering. Other study co-authors include researchers from the University of Pennsylvania, the Carnegie Institution for Science, and Rutgers University. This work included support from DOE's Office of Science, the Army Research Office, the National Science Foundation, the Gordon and Betty Moore Foundation and the Carnegie Institution for Science. Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel Prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy's Office of Science. For more, visit http://www. . DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
News Article | May 25, 2017
RIVERSIDE, Calif. - A team of researchers, led by a plant cell biologist at the University of California, Riverside, has for the first time identified a small RNA species and its target gene that together regulate female germline formation in plants. "Understanding the mechanisms governing germline formation is crucial to our ability to manipulate plant reproduction for the improvement of agriculture," said Xuemei Chen, a distinguished professor of plant cell and molecular biology, who led the research project. In both plants and animals, the germline is the lineage of cells that eventually makes the gametes (eggs and sperms). In animals, the germline is set aside (or "specified") early on, during embryogenesis, and does not go on to give rise to "somatic cells" - cells in the body that are not reproductive cells. In plants, on the other hand, the germline is not specified early on. It is produced from somatic cells late in plant development - specifically, in flowers - and is the first step towards sexual reproduction. The new work not only identifies a regulatory module for an important developmental process, it also implies that there is likely cell-to-cell communications via RNA or protein in this process. Chen explained that small RNAs have been implicated in the process of germline formation in plants, but until now the small RNA species involved, called "tasiR-ARFs," was unknown. Chen and her team found that the tasiR-ARFs regulate germline formation by repressing its target gene Auxin Response Factor 3 (ARF3). Chen explained that in mutants that fail to produce certain types of small RNAs, more somatic cells become germ cells, suggesting that small RNAs prevent the overproduction of germ cells. By isolating more mutants with germline specification defects, the team found that the mutants provided more clues that, eventually, helped the team identify tasiR-ARFs. The research was done on Arabidopsis, a model plant used widely in plant biology labs. The findings, however, are most likely to be applicable to other plants because tasiR-ARF is highly conserved. Chen and her team did not see a defect in male germline in the mutants they studied, but, based on the literature in the field, acknowledge that small RNAs do act in the male germline. "Quite possibly, in the case of the male germline, a different small RNA species is involved," Chen said. Chen, a Howard Hughes Medical Institute - Gordon and Betty Moore Foundation Investigator and a member of the National Academy of Sciences, was joined in the research by Zhenxia Su (first author of the research paper), Yuanyuan Zhao, Shaofang Li, and So Youn Won at UC Riverside; as well as scientists at Fujian Agriculture and Forestry University, China. Chen was funded by grants from the National Institutes of Health, the National Natural Science Foundation of China, and the Guangdong Innovation Research Team Fund for this project. The University of California, Riverside is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment is now nearly 23,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion.
News Article | April 28, 2017
Some of the most promising and puzzling phenomena in physics play out on the nanoscale, where a billionth-of-a-meter shift can make or break perfect electrical conductivity. Now, scientists have developed a new method to probe three-dimensional, atomic-scale intricacies and chemical compositions with unprecedented precision. The breakthrough technique — described February 6 in the journal Nano Letters — combines atomic-force microscopy with near-field spectroscopy to expose the surprising damage wreaked by even the most subtle forces. “This is like granting sight to the blind,” says lead author Adrian Gozar of Yale University. “We can finally see the all-important variations that dictate functionality at this scale and better explore both cutting-edge electronics and fundamental questions that have persisted for decades.” Scientists from Yale University, Harvard University, and the U.S. Department of Energy’s Brookhaven National Laboratory developed the technique to determine why a particular device fabrication technique — helium-ion beam lithography — failed to create the scalable, high-performing superconducting nanowires predicted by both theory and simulation. In previous work, heavy ion beams were used to carve 10-nm-wide channels — some 10,000 times thinner than a human hair — through custom-made materials. However, the new study revealed beam-induced damage rippling out over 50 times that distance. At this scale, that difference was both imperceptible and functionally catastrophic. “This directly addresses the challenge of quantum computing, for example, where companies including IBM and Google are exploring superconducting nanowires but need reliable synthesis and characterization,” says study coauthor and Brookhaven Lab physicist Ivan Bozovic. One promising design for high-temperature superconducting devices is alternating superconductor-insulator-superconductor (SIS) interfaces — or so-called Josephson junctions. These are theoretically easy to fabricate by direct beam writing, assuming sufficient precision can be achieved. Helium-ion beam lithography (HIB) was a perfect candidate, proven recently in similar materials and well suited for swift and scalable production of superconducting nanowires and Josephson junctions. “HIB lets us focus the particle beam to less than a single nanometer and effectively ‘write’ patterns to create superconducting interfaces,” says Nicholas Litombe, who led the HIB work under the guidance of Professor Jenny Hoffman of Harvard, a coauthor of this study. “We set out to shift that technique to another class of materials: LSCO thin films.” The collaboration started with the painstaking assembly of perfect LSCO thin films — so named for their use of lanthanum, strontium, copper, and oxygen. Bozovic’s group at Brookhaven used a technique called atomic layer-by-layer molecular beam epitaxy, which can create atomically perfect superconducting films and heterostructures. “I have a long-standing interest and specialization in using interphase physics to induce and understand high-temperature superconductivity,” Bozovic says. “HIB gives us an entirely new way to explore these materials on the nanoscale.” Litombe carved the ultra-precise interface channels in Bozovic’s thin films. But the immediate results were discouraging: the anticipated superconductivity was entirely suppressed when current ran through wires narrower than a couple hundred nanometers. “Our computer models and experimental results all looked excellent, but we knew there were hidden forces at work,” Litombe says. “We needed deeper insight into the material structure.” Material composition and electronic properties can be pinpointed through the way they absorb and emit light — a longstanding field called spectroscopy. In the instance of superconductivity, this can distinguish between the “shiny” surface of a conductive metal versus the dullness of a current-breaking insulator. The scientists turned to scanning near-field optical microscopy (SNOM) to examine the spectroscopic sheen on the HIB pathways. But this technique, which funnels light through a gilded glass capillary, has a resolution limit of about 100 nanometers — much too large to examine the nanoscale superconducting interfaces. Fortunately, Gozar built a specialized instrument to radically increase the spectroscopic resolution. The machine, built entirely at Brookhaven Lab and now housed at Yale, combines SNOM with atomic force microscopy (AFM). Like a record player’s needle extracting sound from the texture of vinyl, an AFM needle travels over a material and reads the atomic topography. “Here, the AFM needle acts like a lightning rod, channeling the SNOM light down to just tens of nanometers,” Gozar says. “We have simultaneous AFM topography and spectroscopic data on the deep chemical structures.” Crucially, Gozar’s AFM-SNOM system also operates at the cryogenic temperatures required to test these materials — a capability only offered at a few laboratories in the world. The novel technique revealed the unexpected and widespread damage left in the wake of the helium ions. Despite the 0.5-nanometer focus of the beam, its effects rattled atoms across a 500-nanometer spread and altered the structure enough to prevent superconductivity. For nanomaterial construction, this so-called lateral straggle is utterly untenable. “Even the slightest nudge at this scale shatters the powerful phenomena we mean to exploit,” Litombe says. “High-temperature superconductivity can have a coherence distance of just a few atoms, so this lateral effect is devastating. We are, of course, still thrilled to explore the never-before-seen details.” Adds Bozovic, “In one sense, the whole result was negative. Our initial goal of creating nanometer-thick superconducting wires was not fully accomplished. But figuring out why has opened some truly exciting doors.” The SNOM-AFM technique is readily applicable to fields such as plasmonics for display technology and the study of the mechanism behind high-temperature superconductivity. “The nanoscale resolution and the tomographic capabilities of the instrument, put us on the cusp of uncovering new truths about nanoscale phenomena and the technology it empowers,” Gozar says. This research was supported by the U.S. Department of Energy’s Office of Science and the Gordon and Betty Moore Foundation.
News Article | April 25, 2017
Researchers have devised a more accurate way to predict and measure the impact products have on the environment. Using a process called life-cycle assessment, companies often test the environmental impact their products may have—as well as the impact of producing the components, such as corn or sugarcane, that go into those products. This kind of assessment, however, often lacks detail about how the products affect natural resources such as land, water, and biodiversity. The researchers tested this new LCA, called Land Use Change Improved Life Cycle Assessment, or LUCI-LCA, by evaluating the potential environmental impacts of two bio-plastic products that could come from sugarcane grown in Mato Grosso, Brazil, or from corn grown in Iowa. Their approach—which includes more accurate data about the regional land composition than the traditional LCA—came to different conclusions about which option would be more environmentally responsible. The group reports the results in Nature Communications. “The size and reach of multinational companies is stunning, on par with that of many nations,” says Gretchen Daily, professor of biology at Stanford University and senior author of the paper. “When we think about how to bring human activities into balance with what Earth can sustain, corporations have a major role to play in decoupling economic growth from environmental impact.” Life-cycle assessment offers a systematic way of determining potential environmental impacts of a product from source materials to disposal. Results from these assessments often inform decisions companies make about product design, material, and technology choices and sourcing strategies. An incomplete or inaccurate assessment could lead to well intentioned but environmentally damaging decisions. One problem with a standard life cycle assessment is that it represents the average land composition of the country from which materials will be sourced. So, in this case, it assumes that Mato Grosso contains the same proportion of rainforest as all of Brazil, and that sourcing sugarcane from that state would lead to deforestation of the Amazon. Daily and her colleagues made improvements that allow for more refined assessment using data relevant to the exact regions from which materials would likely be sourced, taking into account predictions about future impacts to the environment. “In reality, from the modeling that we did, it looked like most of the expansion of agriculture in Mato Grosso would happen in the savannah,” says Rebecca Chaplin-Kramer, research associate at the Stanford Woods Institute for the Environment and lead author of the study. “Whereas in Iowa, if any expansion happens, it will likely mean expanding into forest.” While the standard LCA showed that the Mato Grosso sugarcane would lead to more CO in the atmosphere, this more spatially sensitive LCA found that the carbon footprint of the Iowan corn was larger. In addition, while the traditional LCA found that the corn would result in more water use than the sugarcane, the new LCA found that the sugarcane would use more—900 percent more. “This work has major implications for anybody involved in product innovation, commodity sourcing, or policy setting for new land development,” says Ryan Noe, a researcher with the National Capital Project at University of Minnesota and coauthor of the paper. “Where that sourcing comes from matters and it’s not really being captured with the approaches being used.” The researchers hope that the stark and significant differences between the results of the two LCAs will encourage companies and policymakers to adopt the new approach for decision-making. It took the team substantial time and effort to pull together the data necessary for this case study. But with increased interest, they believe they could develop a more streamlined tool that would require little manual work. “There’s more work at some levels—but this is exactly the kind of 21st-century work that responsible corporations are pursuing to promote green growth and a sustainable human enterprise,” Daily says. “In the short run, this approach will reduce costs and risks. In the long run, it is utterly key to survival.” Additional coauthors contributed from Stanford, the University of Minnesota, the Natural Capital project, and Unilever. Unilever and the Gordon and Betty Moore Foundation funded this research.
News Article | May 5, 2017
Control of light-matter interaction is central to fundamental phenomena and technologies such as photosynthesis, lasers, LEDs and solar cells. City College of New York researchers have now demonstrated a new class of artificial media called photonic hypercrystals that can control light-matter interaction in unprecedented ways. This could lead to such benefits as ultrafast LEDs for Li-Fi (a wireless technology that transmits high-speed data using visible light communication), enhanced absorption in solar cells and the development of single photon emitters for quantum information processing, said Vinod M. Menon, professor of physics in City College's Division of Science who led the research. Photonic crystals and metamaterials are two of the most well-known artificial materials used to manipulate light. However, they suffer from drawbacks such as bandwidth limitation and poor light emission. In their research, Menon and his team overcame these drawbacks by developing hypercrystals that take on the best of both photonic crystals and metamaterials and do even better. They demonstrated significant increase in both light emission rate and intensity from nanomaterials embedded inside the hypercrystals. The emergent properties of the hypercrystals arise from the unique combination of length scales of the features in the hypercrystal as well as the inherent properties of the nanoscale structures. The CCNY research appears in the latest issue of the Proceedings of the National Academy of Sciences. The team included graduate students Tal Galfsky and Jie Gu from Menon's research group in CCNY's Physics Department and Evgenii Narimanov (Purdue University), who first theoretically predicted the hypercrystals. The research was supported by the Army Research Office, the National Science Foundation - Division of Materials Research MRSEC program, and the Gordon and Betty Moore Foundation.
News Article | May 5, 2017
Abstract: Control of light-matter interaction is central to fundamental phenomena and technologies such as photosynthesis, lasers, LEDs and solar cells. City College of New York researchers have now demonstrated a new class of artificial media called photonic hypercrystals that can control light-matter interaction in unprecedented ways. New York, NY | Posted on May 5th, 2017 This could lead to such benefits as ultrafast LEDs for Li-Fi (a wireless technology that transmits high-speed data using visible light communication), enhanced absorption in solar cells and the development of single photon emitters for quantum information processing, said Vinod M. Menon, professor of physics in City College's Division of Science who led the research. Photonic crystals and metamaterials are two of the most well-known artificial materials used to manipulate light. However, they suffer from drawbacks such as bandwidth limitation and poor light emission. In their research, Menon and his team overcame these drawbacks by developing hypercrystals that take on the best of both photonic crystals and metamaterials and do even better. They demonstrated significant increase in both light emission rate and intensity from nanomaterials embedded inside the hypercrystals. The emergent properties of the hypercrystals arise from the unique combination of length scales of the features in the hypercrystal as well as the inherent properties of the nanoscale structures. The CCNY research appears in the latest issue of the Proceedings of the National Academy of Sciences. The team included graduate students Tal Galfsky and Jie Gu from Menon's research group in CCNY's Physics Department and Evgenii Narimanov (Purdue University), who first theoretically predicted the hypercrystals. The research was supported by the Army Research Office, the National Science Foundation - Division of Materials Research MRSEC program, and the Gordon and Betty Moore Foundation. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
News Article | May 5, 2017
This could lead to such benefits as ultrafast LEDs for Li-Fi (a wireless technology that transmits high-speed data using visible light communication), enhanced absorption in solar cells and the development of single photon emitters for quantum information processing, said Vinod M. Menon, professor of physics in City College's Division of Science who led the research. Photonic crystals and metamaterials are two of the most well-known artificial materials used to manipulate light. However, they suffer from drawbacks such as bandwidth limitation and poor light emission. In their research, Menon and his team overcame these drawbacks by developing hypercrystals that take on the best of both photonic crystals and metamaterials and do even better. They demonstrated significant increase in both light emission rate and intensity from nanomaterials embedded inside the hypercrystals. The emergent properties of the hypercrystals arise from the unique combination of length scales of the features in the hypercrystal as well as the inherent properties of the nanoscale structures. The CCNY research appears in the latest issue of the Proceedings of the National Academy of Sciences. The team included graduate students Tal Galfsky and Jie Gu from Menon's research group in CCNY's Physics Department and Evgenii Narimanov (Purdue University), who first theoretically predicted the hypercrystals. The research was supported by the Army Research Office, the National Science Foundation - Division of Materials Research MRSEC program, and the Gordon and Betty Moore Foundation. More information: Tal Galfsky et al. Photonic hypercrystals for control of light–matter interactions, Proceedings of the National Academy of Sciences (2017). DOI: 10.1073/pnas.1702683114
News Article | May 5, 2017
In normal conductive materials such as silver and copper, electric current flows with varying degrees of resistance, in the form of individual electrons that ping-pong off defects, dissipating energy as they go. Superconductors, by contrast, are so named for their remarkable ability to conduct electricity without resistance, by means of electrons that pair up and move through a material as one, generating no friction. Now MIT physicists have found that a flake of graphene, when brought in close proximity with two superconducting materials, can inherit some of those materials’ superconducting qualities. As graphene is sandwiched between superconductors, its electronic state changes dramatically, even at its center. The researchers found that graphene’s electrons, formerly behaving as individual, scattering particles, instead pair up in “Andreev states” — a fundamental electronic configuration that allows a conventional, nonsuperconducting material to carry a “supercurrent,” an electric current that flows without dissipating energy. Their findings, published this week in Nature Physics, are the first investigation of Andreev states due to superconductivity’s “proximity effect” in a two-dimensional material such as graphene. Down the road, the researchers’ graphene platform may be used to explore exotic particles, such as Majorana fermions, which are thought to arise from Andreev states and may be key particles for building powerful, error-proof quantum computers. “There is a huge effort in the condensed physics community to look for exotic quantum electronic states,” says lead author Landry Bretheau, a postdoc in MIT’s Department of Physics. “In particular, new particles called Majorana fermions are predicted to emerge in graphene that is connected to superconducting electrodes and exposed to large magnetic fields. Our experiment is promising, as we are unifying some of these ingredients.” Landry’s MIT co-authors are postdoc Joel I-Jan Wang, visiting student Riccardo Pisoni, and associate professor of physics Pablo Jarillo-Herrero, along with Kenji Watanabe and Takashi Taniguchi of the National Institute for Materials Science, in Japan. In 1962, the British physicist Brian David Josephson predicted that two superconductors sandwiching a nonsuperconducting layer between them could sustain a supercurrent of electron pairs, without any external voltage. As a whole, the supercurrent associated with the Josephson effect has been measured in numerous experiments. But Andreev states — considered the microscopic building blocks of a supercurrent — have been observed only in a handful of systems, such as silver wires, and never in a two-dimensional material. Bretheau, Wang, and Jarillo-Herrero tackled this issue by using graphene — an ultrathin sheet of interlinked carbon atoms — as the nonsuperconducting material. Graphene, as Bretheau explains, is an extremely “clean” system, exhibiting very little scattering of electrons. Graphene’s extended, atomic configuration also enables scientists to measure graphene’s electronic Andreev states as the material comes in contact with superconductors. Scientists can also control the density of electrons in graphene and investigate how it affects the superconducting proximity effect. The researchers exfoliated a very thin flake of graphene, just a few hundred nanometers wide, from a larger chunk of graphite, and placed the flake on a small platform made from a crystal of boron nitride overlaying a sheet of graphite. On either end of the graphene flake, they placed an electrode made from aluminum, which behaves as a superconductor at low temperatures. They then placed the entire structure in a dilution refrigerator and lowered the temperature to 20 millikelvin — well within aluminum’s superconducting range. In their experiments, the researchers varied the magnitude of the supercurrent flowing between the superconductors by applying a changing magnetic field to the entire structure. They also applied an external voltage directly to graphene, to vary the number of electrons in the material. Under these changing conditions, the team measured the graphene’s density of electronic states while the flake was in contact with both aluminum superconductors. Using tunneling spectroscopy, a common technique that measures the density of electronic states in a conductive sample, the researchers were able to probe the graphene’s central region to see whether the superconductors had any effect, even in areas where they weren’t physically touching the graphene. The measurements indicated that graphene’s electrons, which normally act as individual particles, were pairing up, though in “frustrated” configurations, with energies dependent on magnetic field. “Electrons in a superconductor dance harmoniously in pairs, like a ballet, but the choreography in the left and right superconductors can be different,” Bretheau says. “Pairs in the central graphene are frustrated as they try to satisfy both ways of dancing. These frustrated pairs are what physicists know as Andreev states; they are carrying the supercurrent.” Bretheau and Wang found Andreev states vary their energy in response to a changing magnetic field. Andreev states are more pronounced when graphene has a higher density of electrons and there is a stronger supercurrent running between electrodes. “[The superconductors] are actually giving graphene some superconducting qualities,” Bretheau says. “We found these electrons can be dramatically affected by superconductors.” While the researchers carried out their experiments under low magnetic fields, they say their platform may be a starting point for exploring the more exotic Majorana fermions that should appear under high magnetic fields. “There are proposals for how to use Majorana fermions to build powerful quantum computers,” Bretheau says. “These particles could be the elementary brick of topological quantum computers, with very strong protection against errors. Our work is an initial step in this direction.” This work was supported, in part, by the U.S. Department of Energy, and the Gordon and Betty Moore Foundation.
News Article | May 3, 2017
Think of life as a house: if DNA molecules are blueprints, then messenger RNAs (mRNAs) are orders, describing the required parts (proteins) and when they should arrive. But putting in many orders doesn't always mean you'll get all of the parts on time -- maybe there's a delay with your vendor or delivery service. Similarly, mRNA levels alone do not dictate protein levels. Today in ACS Central Science, researchers report a method to address that issue. David Tirrell, Kelly Burke and Katie Antilla note that in order to better understand how genes are regulated, one needs to see the mRNA when it is at the site of protein synthesis. Using fluorescence probes, the researchers designed a technique that shows mRNA when it comes in contact with giant protein synthesizing machines called ribosomes. They used this method to record the synthesis of proteins and to measure cellular responses to iron. Unlike previous methods, their tool works without the need to engineer an mRNA of interest. Tirrell notes that the method is applicable to essentially any type of RNA, and could be modified to visualize other types of interactions in the cell. The authors acknowledge funding from the National Science Foundation, Rose Hills Foundation, German Research Foundation and the Gordon and Betty Moore Foundation. The paper will be freely available on May 3 here: http://pubs. The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. ACS does not conduct research, but publishes and publicizes peer-reviewed scientific studies. Its main offices are in Washington, D.C., and Columbus, Ohio. To automatically receive news releases from the American Chemical Society, contact firstname.lastname@example.org.
News Article | May 2, 2017
The National Academy of Sciences announced today the election of 84 new members and 21 foreign associates in recognition of their distinguished and continuing achievements in original research. The National Academy of Sciences announced today the election of 84 new members and 21 foreign associates in recognition of their distinguished and continuing achievements in original research. Those elected today bring the total number of active members to 2,290 and the total number of foreign associates to 475. Foreign associates are nonvoting members of the Academy, with citizenship outside the United States. Newly elected members and their affiliations at the time of election are: Bates, Frank S.; Regents Professor, department of chemical engineering and materials science, University of Minnesota, Minneapolis Beilinson, Alexander; David and Mary Winton Green University Professor, department of mathematics, The University of Chicago, Chicago Bell, Stephen P.; investigator, Howard Hughes Medical Institute; and professor of biology, department of biology, Massachusetts Institute of Technology, Cambridge Bhatia, Sangeeta N.; John J. (1929) and Dorothy Wilson Professor, Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge Buzsáki, György; professor, Neuroscience Institute, departments of physiology and neuroscience, New York University Langone Medical Center, New York City Carroll, Dana; distinguished professor, department of biochemistry, University of Utah School of Medicine, Salt Lake City Cohen, Judith G.; Kate Van Nuys Page Professor of Astronomy, department of astronomy, California Institute of Technology, Pasadena Crabtree, Robert H.; Conkey P. Whitehead Professor of Chemistry, department of chemistry, Yale University, New Haven, Conn. Cronan, John E.; professor and head of microbiology, professor of biochemistry, and Microbiology Alumni Professor, department of microbiology, University of Illinois, Urbana-Champaign Cummins, Christopher C.; Henry Dreyfus Professor of Chemistry, Massachusetts Institute of Technology, Cambridge Darensbourg, Marcetta Y.; distinguished professor of chemistry, department of chemistry, Texas A&M University, College Station DeVore, Ronald A.; The Walter E. Koss Professor and distinguished professor, department of mathematics, Texas A&M University, College Station Diamond, Douglas W.; Merton H. Miller Distinguished Service Professor of Finance, The University of Chicago, Chicago Doe, Chris Q.; investigator, Howard Hughes Medical Institute; and professor of biology, Institute of Molecular Biology, University of Oregon, Eugene Duflo, Esther; Co-founder and co-Director of the Abdul Latif Jameel Poverty Action Lab, and Professor of Poverty Alleviation and Development Economics, Massachusetts Institute of Technology, Cambridge Edwards, Robert Haas; professor of neurology and physiology, University of California, San Francisco Firestone, Mary K.; professor and associate dean of instruction and student affairs, department of environmental science policy and management, University of California, Berkeley Fischhoff, Baruch; Howard Heinz University Professor, department of social and decision sciences and department of engineering and public policy, Carnegie Mellon University, Pittsburgh Ginty, David D.; investigator, Howard Hughes Medical Institute; and Edward R. and Anne G. Lefler Professor of Neurobiology, department of neurobiology, Harvard Medical School, Boston Glass, Christopher K.; professor of cellular and molecular medicine and professor of medicine, University of California, San Diego Goldman, Yale E.; professor, department of physiology, Pennsylvania Muscle Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia González, Gabriela; spokesperson, LIGO Scientific Collaboration; and professor, department of physics and astronomy, Louisiana State University, Baton Rouge Hagan, John L.; John D. MacArthur Professor of Sociology and Law, department of sociology, Northwestern University, Evanston, Ill. Hatten, Mary E.; Frederick P. Rose Professor, laboratory of developmental neurobiology, The Rockefeller University, New York City Hebard, Arthur F.; distinguished professor of physics, department of physics, University of Florida, Gainesville Jensen, Klavs F.; Warren K. Lewis Professor of Chemical Engineering and professor of materials science and engineering, Massachusetts Institute of Technology, Cambridge Kahn, Barbara B.; vice chair for research strategy and George R. Minot Professor of Medicine at Harvard Medical School, Beth Israel Deaconess Medical Center, Boston Kinder, Donald R.; Philip E. Converse Collegiate Professor of Political Science and Psychology and research scientist, department of political science, Center for Political Studies, Institute for Social Research, University of Michigan, Ann Arbor Lazar, Mitchell A.; Willard and Rhoda Ware Professor in Diabetes and Metabolic Diseases, and director, Institute for Diabetes, Obesity, and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia Locksley, Richard M.; investigator, Howard Hughes Medical Institute; and professor, department of medicine (infectious diseases), and Marion and Herbert Sandler Distinguished Professorship in Asthma Research, University of California, San Francisco Lozano, Guillermina; professor and chair, department of genetics, The University of Texas M.D. Anderson Cancer Center, Houston Mavalvala, Nergis; Curtis and Kathleen Marble Professor of Astrophysics and associate head, department of physics, Massachusetts Institute of Technology, Cambridge Moore, Jeffrey Scott; Murchison-Mallory Professor of Chemistry, department of chemistry, University of Illinois, Urbana-Champaign Moore, Melissa J.; chief scientific officer, mRNA Research Platform, Moderna Therapeutics, Cambridge, Mass.; and Eleanor Eustis Farrington Chair of Cancer Research Professor, RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester Nunnari, Jodi M.; professor, department of molecular and cellular biology, University of California, Davis O'Farrell, Patrick H.; professor of biochemistry and biophysics, department of biochemistry and biophysics, University of California, San Francisco Ort, Donald R.; research leader and Robert Emerson Professor, USDA/ARS Global Change and Photosynthesis Research Unit, departments of plant biology and crop sciences, University of Illinois, Urbana-Champaign Parker, Gary; professor, department of civil and environmental engineering and department of geology, University of Illinois, Urbana-Champaign Patapoutian, Ardem; investigator, Howard Hughes Medical Institute; and professor, department of molecular and cellular neuroscience, The Scripps Research Institute, La Jolla, Calif. Pellegrini, Claudio; distinguished professor emeritus, department of physics and astronomy, University of California, Los Angeles Pikaard, Craig, S.; investigator, Howard Hughes Medical Institute and Gordon and Betty Moore Foundation; and distinguished professor of biology and molecular and cellular biochemistry, department of biology, Indiana University, Bloomington Read, Nicholas; Henry Ford II Professor of Physics and professor of applied physics and mathematics, Yale University, New Haven, Conn. Roediger, Henry L.; James S. McDonnell Distinguished and University Professor of Psychology, department of psychology and brain sciences, Washington University, St. Louis Rosenzweig, Amy C.; Weinberg Family Distinguished Professor of Life Sciences, and professor, departments of molecular biosciences and of chemistry, Northwestern University, Evanston, Ill. Seto, Karen C.; professor, Yale School of Forestry and Environmental Studies, New Haven, Conn. Seyfarth, Robert M.; professor of psychology and member of the graduate groups in anthropology and biology, University of Pennsylvania, Philadelphia Sibley, L. David; Alan A. and Edith L. Wolff Distinguished Professor in Molecular Microbiology, department of molecular microbiology, Washington University School of Medicine, St. Louis Spielman, Daniel A.; Henry Ford II Professor of Computer Science and Mathematics, departments of computer science and mathematics, Yale University, New Haven, Conn. Sudan, Madhu; Gordon McKay Professor of Computer Science, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Mass. Tishkoff, Sarah; David and Lyn Silfen University Professor, departments of genetics and biology, University of Pennsylvania, Philadelphia Van Essen, David C.; Alumni Professor of Neurobiology, department of anatomy and neurobiology, Washington University School of Medicine, St. Louis Vidale, John E.; professor, department of earth and space sciences, University of Washington, Seattle Wennberg, Paul O.; R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering, California Institute of Technology, Pasadena Wilson, Rachel I.; Martin Family Professor of Basic Research in the Field of Neurobiology, department of neurobiology, Harvard Medical School, Boston Zachos, James C.; professor, department of earth and planetary sciences, University of California, Santa Cruz, Santa Cruz Newly elected foreign associates, their affiliations at the time of election, and their country of citizenship are: Addadi, Lia; professor and Dorothy and Patrick E. Gorman Chair of Biological Ultrastructure, department of structural science, Weizmann Institute of Science, Rehovot, Israel (Israel/Italy) Folke, Carl; director and professor, The Beijer Institute of Ecological Economics, Royal Swedish Academy of Sciences, Stockholm, Sweden (Sweden) Freeman, Kenneth C.; Duffield Professor of Astronomy, Mount Stromlo and Siding Spring Observatories, Research School of Astronomy and Astrophysics, Australian National University, Weston Creek (Australia) Lee, Sang Yup; distinguished professor, dean, and director, department of chemical and biomolecular engineering, Korea Advanced Institute of Science and Technology, Daejeon, South Korea (South Korea) Levitzki, Alexander; professor of biochemistry, unit of cellular signaling, department of biological chemistry, The Hebrew University of Jerusalem, Jerusalem (Israel) Peiris, Joseph Sriyal Malik; Tam Wah-Ching Professorship in Medical Science, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong, People's Republic of China (Sri Lanka) Robinson, Carol Vivien; Dr. Lee's Professor of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, England (United Kingdom) Thesleff, Irma; academician of science, professor, and research director, developmental biology program, Institute of Biotechnology, University of Helsinki, Helsinki (Finland) Underdal, Arild; professor of political science, department of political science, University of Oslo, Oslo, Norway (Norway) The National Academy of Sciences is a private, nonprofit institution that was established under a congressional charter signed by President Abraham Lincoln in 1863. It recognizes achievement in science by election to membership, and -- with the National Academy of Engineering and the National Academy of Medicine -- provides science, engineering, and health policy advice to the federal government and other organizations.