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  • richardmitnick 1:40 pm on June 18, 2018 Permalink | Reply
    Tags: , Convert nanoparticle-coated microscopic beads into lasers smaller than red blood cells, , , Nanotechnology   

    From Lawrence Berkeley National Lab: “Scientists Create Continuously Emitting Microlasers With Nanoparticle-Coated Beads” 

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    From Lawrence Berkeley National Lab

    Glenn Roberts Jr.
    (510) 486-5582

    At left, a tiny bead struck by a laser (at the yellowish spot shown at the top of the image) produces optical modes that circulate around the interior of the bead (pinkish ring). At right, a simulation of how the optical field inside a 5-micron (5 millionths of a meter) bead is distributed. (Credit: Angel Fernandez-Bravo/Berkeley Lab, Kaiyuan Yao)

    Researchers have found a way to convert nanoparticle-coated microscopic beads into lasers smaller than red blood cells.

    These microlasers, which convert infrared light into light at higher frequencies, are among the smallest continuously emitting lasers of their kind ever reported and can constantly and stably emit light for hours at a time, even when submerged in biological fluids such as blood serum.

    The innovation, discovered by an international team of scientists at the U.S. Department of Energy’s Lawrence Berkeley Laboratory (Berkeley Lab), opens up the possibility for imaging or controlling biological activity with infrared light, and for the fabrication of light-based computer chips. Their findings are detailed in a report published online June 18 in Nature Nanotechnology.

    The unique properties of these lasers, which measure 5 microns (millionths of a meter) across, were discovered by accident as researchers were studying the potential for the polymer (plastic) beads, composed of a translucent substance known as a colloid, to be used in brain imaging.

    A scanning electron micrograph image (left) of a 5-micron-diameter polystyrene bead that is coated with nanoparticles, and a transmission electron micrograph image (right) that shows a cross-section of a bead, with nanoparticles along its outer surface. The scale bar at left is 1 micron, and the scale bar at right is 20 nanometers. (Credit: Angel Fernandez-Bravo, Shaul Aloni/Berkeley Lab)

    Angel Fernandez-Bravo, a postdoctoral researcher at Berkeley Lab’s Molecular Foundry, who was the lead author of study, mixed the beads with sodium yttrium fluoride nanoparticles “doped,” or embedded, with thulium, an element belonging to a group of metals known as lanthanides. The Molecular Foundry is a nanoscience research center open to researchers from around the world.

    LBNL Molecular Foundry – No image credits found

    Emory Chan, a Staff Scientist at the Molecular Foundry, had in 2016 used computational models to predict that thulium-doped nanoparticles exposed to infrared laser light at a specific frequency could emit light at a higher frequency than this infrared light in a counterintuitive process known as “upconversion.”

    Also at that time, Elizabeth Levy, then a participant in the Lab’s Summer Undergraduate Laboratory Internship (SULI) program, noticed that beads coated with these “upconverting nanoparticles” emitted unexpectedly bright light at very specific wavelengths, or colors.

    “These spikes were clearly periodic and clearly reproducible,” said Emory Chan, who co-led the study along with Foundry Staff Scientists Jim Schuck (now at Columbia University) and Bruce Cohen.

    The periodic spikes that Chan and Levy had observed are a light-based analog to so-called “whispering gallery” acoustics that can cause sound waves to bounce along the walls of a circular room so that even a whisper can be heard on the opposite side of the room. This whispering-gallery effect was observed in the dome of St. Paul’s Cathedral in London in the late 1800s, for example.

    In the latest study, Fernandez-Bravo and Schuck found that when an infrared laser excites the thulium-doped nanoparticles along the outer surface of the beads, the light emitted by the nanoparticles can bounce around the inner surface of the bead just like whispers bouncing along the walls of the cathedral.

    A wide-field image showing the light emitted by microlasers in a self-assembled 2D array. (Credit: Angel Fernandez-Bravo)

    Light can make thousands of trips around the circumference of the microsphere in a fraction of a second, causing some frequencies of light to interact (or “interfere”) with themselves to produce brighter light while other frequencies cancel themselves out. This process explains the unusual spikes that Chan and Levy observed.

    When the intensity of light traveling around these beads reaches a certain threshold, the light can stimulate the emission of more light with the exact same color, and that light, in turn, can stimulate even more light. This amplification of light, the basis for all lasers, produces intense light at a very narrow range of wavelengths in the beads.

    Schuck had considered lanthanide-doped nanoparticles as potential candidates for microlasers, and he became convinced of this when Chan shared with him the periodic whispering-gallery data.

    Fernandez-Bravo found that when he exposed the beads to an infrared laser with enough power the beads turned into upconverting lasers, with higher frequencies than the original laser.

    He also found that beads could produce laser light at the lowest powers ever recorded for upconverting nanoparticle-based lasers.

    “The low thresholds allow these lasers to operate continuously for hours at much lower powers than previous lasers,” said Fernandez-Bravo.

    Other upconverting nanoparticle lasers operate only intermittently; they are only exposed to short, powerful pulses of light because longer exposure would damage them.

    “Most nanoparticle-based lasers heat up very quickly and die within minutes,” Schuck said. “Our lasers are always on, which allows us to adjust their signals for different applications.”

    In this case, researchers found that their microlasers performed stably after five hours of continuous use. “We can take the beads off the shelf months or years later, and they still lase,” Fernandez-Bravo said.

    Researchers are also exploring how to carefully tune the output light from the continuously emitting microlasers by simply changing the size and composition of the beads. And they have used a robotic system at the Molecular Foundry known as WANDA (Workstation for Automated Nanomaterial Discovery and Analysis) to combine different dopant elements and tune the nanoparticles’ performance.

    The researchers also noted that there are many potential applications for the microlasers, such as in controlling the activity of neurons or optical microchips, sensing chemicals, and detecting environmental and temperature changes.

    “At first these microlasers only worked in air, which was frustrating because we wanted to introduce them into living systems,” Cohen said. “But we found a simple trick of dipping them in blood serum, which coats the beads with proteins that allow them to lase in water. We’ve now seen that these beads can be trapped along with cells in laser beams and steered with the same lasers we use to excite them.”

    The latest study, and the new paths of study it has opened up, shows how fortuitous an unexpected result can be, he said. “We just happened to have the right nanoparticles and coating process to produce these lasers,” Schuck said.

    Researchers from UC Berkeley, the National Laboratory of Astana in Kazakhstan, the Polytechnic University of Milan, and Columbia University in New York also participated in this study. This work was supported by the DOE Office of Science, and by the Ministry of Education and Science of the Republic of Kazakhstan.

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  • richardmitnick 5:23 pm on June 11, 2018 Permalink | Reply
    Tags: , , Graphene yet again, , Monitoring electromagnetic radiation, Nanotechnology, The graphene is coupled to a device called a photonic nanocavity   

    From MIT News: “A better device for measuring electromagnetic radiation” 

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    From MIT News

    June 11, 2018
    David Chandler

    Schematic illustration of the experimental setup. Image courtesy of the researchers

    New bolometer is faster, simpler, and covers more wavelengths.

    Bolometers, devices that monitor electromagnetic radiation through heating of an absorbing material, are used by astronomers and homeowners alike. But most such devices have limited bandwidth and must be operated at ultralow temperatures. Now, researchers say they’ve found a ultrafast yet highly sensitive alternative that can work at room temperature — and may be much less expensive.

    The findings, published today in the journal Nature Nanotechnology, could help pave the way toward new kinds of astronomical observatories for long-wavelength emissions, new heat sensors for buildings, and even new kinds of quantum sensing and information processing devices, the multidisciplinary research team says. The group includes recent MIT postdoc Dmitri Efetov, Professor Dirk Englund of MIT’s Department of Electrical Engineering and Computer Science, Kin Chung Fong of Raytheon BBN Technologies, and colleagues from MIT and Columbia University.

    “We believe that our work opens the door to new types of efficient bolometers based on low-dimensional materials,” says Englund, the paper’s senior author. He says the new system, based on the heating of electrons in a small piece of a two-dimensional form of carbon called graphene, for the first time combines both high sensitivity and high bandwidth — orders of magnitude greater than that of conventional bolometers — in a single device.

    “The new device is very sensitive, and at the same time ultrafast,” having the potential to take readings in just picoseconds (trillionths of a second), says Efetov, now a professor at ICFO, the Institute of Photonic Sciences in Barcelona, Spain, who is the paper’s lead author. “This combination of properties is unique,” he says.

    The new system also can operate at any temperature, he says, unlike current devices that have to be cooled to extremely low temperatures. Although most actual applications of the device would still be done under these ultracold conditions, for some applications, such as thermal sensors for building efficiency, the ability to operate without specialized cooling systems could be a real plus. “This is the first device of this kind that has no limit on temperature,” Efetov says.

    The new bolometer they built, and demonstrated under laboratory conditions, can measure the total energy carried by the photons of incoming electromagnetic radiation, whether that radiation is in the form of visible light, radio waves, microwaves, or other parts of the spectrum. That radiation may be coming from distant galaxies, or from the infrared waves of heat escaping from a poorly insulated house.

    The device is entirely different from traditional bolometers, which typically use a metal to absorb the radiation and measure the resulting temperature rise. Instead, this team developed a new type of bolometer that relies on heating electrons moving in a small piece of graphene, rather than heating a solid metal. The graphene is coupled to a device called a photonic nanocavity, which serves to amplify the absorption of the radiation, Englund explains.

    “Most bolometers rely on the vibrations of atoms in a piece of material, which tends to make their response slow,” he says. In this case, though, “unlike a traditional bolometer, the heated body here is simply the electron gas, which has a very low heat capacity, meaning that even a small energy input due to absorbed photons causes a large temperature swing,” making it easier to make precise measurements of that energy. Although graphene bolometers had previously been demonstrated, this work solves some of the important outstanding challenges, including efficient absorption into the graphene using a nanocavity, and the impedance-matched temperature readout.

    The new technology, Englund says, “opens a new window for bolometers with entirely new functionalities that could radically improve thermal imaging, observational astronomy, quantum information, and quantum sensing, among other applications.”

    For astronomical observations, the new system could help by filling in some of the remaining wavelength bands that have not yet had practical detectors to make observations, such as the “terahertz gap” of frequencies that are very difficult to pick up with existing systems. “There, our detector could be a state-of-the-art system” for observing these elusive rays, Efetov says. It could be useful for observing the very long-wavelength cosmic background radiation, he says.

    Daniel Prober, a professor of applied physics at Yale University who was not involved in this research, says, “This work is a very good project to utilize the many benefits of the ultrathin metal layer, graphene, while cleverly working around the limitations that would otherwise be imposed by its conducting nature.” He adds, “The resulting detector is extremely sensitive for power detection in a challenging region of the spectrum, and is now ready for some exciting applications.”

    And Robert Hadfield, a professor of photonics at the University of Glasgow, who also was not involved in this work, says, “There is huge demand for new high-sensitivity infrared detection technologies. This work by Efetov and co-workers reporting an innovative graphene bolometer integrated in a photonic crystal cavity to achieve high absorption is timely and exciting.”

    See the full article here .

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  • richardmitnick 11:16 am on April 23, 2018 Permalink | Reply
    Tags: , , , , Nanoparticle Breakthrough Could Capture Unseen Light for Solar Energy Conversion, Nanotechnology, UCNPs - upconverting nanoparticles   

    From Lawrence Berkeley National Lab: “Nanoparticle Breakthrough Could Capture Unseen Light for Solar Energy Conversion” 

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    Lawrence Berkeley National Lab

    April 23, 2018
    Glenn Roberts Jr.
    (510) 486-5582

    Scientists demonstrate how organic dyes work as antennas to help harness, convert light.

    ANIMATION: Energy transfers from a ytterbium atom (blue), which absorbs near-infrared light, to an erbium atom (red). The erbium atom then releases visible, green light. A study led by researchers at Berkeley Lab’s Molecular Foundry found a way to enhance this process, known as “upconversion,” by coating nanoparticles with dyes. Scientists hope to use this process to develop solar cells that capture and convert previously missed sunlight into usable energy. (Credit: Andrew Mueller)

    An international team of scientists has demonstrated a breakthrough in the design and function of nanoparticles that could make solar panels more efficient by converting light usually missed by solar cells into usable energy.

    The team, led by scientists at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), demonstrated how coating tiny particles with organic dyes greatly enhances their ability to capture near-infrared light and to reemit the light in the visible light spectrum, which could also be useful for biological imaging.

    Once they understood the mechanism that enables the dyes on nanoparticles to function as antennas to gather a broad range of light, they successfully reengineered the nanoparticles to further amplify the particles’ light-converting properties. Their study was published online April 23 in Nature Photonics.

    “These organic dyes capture broad swaths of near-infrared light,” said Bruce Cohen, a scientist at Berkeley Lab’s Molecular Foundry who helped to lead the study along with Molecular Foundry scientists P. James Schuck (now at Columbia University), and Emory Chan. The Molecular Foundry is a nanoscience research center.

    “Since the near-infrared wavelengths of light are often unused in solar technologies that focus on visible light,” Cohen added, “and these dye-sensitized nanoparticles efficiently convert near-infrared light to visible light, they raise the possibility of capturing a good portion of the solar spectrum that otherwise goes to waste, and integrating it into existing solar technologies.”

    Researchers found that the dye itself amplifies the brightness of the reemitted light about 33,000-fold, and its interaction with the nanoparticles increases its efficiency in converting light by about 100 times.

    An erbium atom (red) in a nanocrystal emits visible, green light via a process known as upconversion that could lead to the development of improved solar cells that capture some previously missed solar energy. Scientists discovered that coating the particles with dyes (blue and purple molecules at right) can greatly enhance this light-converting property. (Credit: Berkeley Lab)

    Cohen, Schuck, and Chan had worked for about a decade to design, fabricate, and study the upconverting nanoparticles (UCNPs) used in this study. UCNPs absorb near-infrared light and efficiently convert it to visible light, an unusual property owing to combinations of lanthanide metal ions in the nanocrystals. A 2012 study suggested that dyes on the UCNPs’ surface dramatically enhances the particles’ light-converting properties, but the mechanism remained a mystery.

    “There was a lot of excitement and then a lot of confusion,” Cohen said. “It had us scratching our heads.”

    Although many researchers had tried to reproduce the study in the following years, “Few people could get the published procedure to work,” added Chan. “The dyes appeared to degrade almost immediately upon exposure to light, and nobody knew exactly how the dyes were interacting with the nanoparticle surface.”

    The unique mix of expertise and capabilities at the Molecular Foundry, which included theoretical work and a mix of experiments, chemistry know-how, and well-honed synthetic techniques, made the latest study possible, he noted. “It’s one of those projects that would be difficult to do anywhere else.”

    Experiments led by David Garfield, a UC Berkeley Ph.D. student, and Nicholas Borys, a Molecular Foundry project scientist, showed a symbiotic effect between the dye and the lanthanide metals in the nanoparticles.

    The proximity of the dyes to the lanthanides in the particles enhances the presence of a dye state known as a “triplet,” which then transfers its energy to the lanthanides more efficiently. The triplet state allowed a more efficient conversion of multiple infrared units of light, known as photons, into single photons of visible light.

    The studies showed that a match in the measurements of the dye’s light emission and the particles’ light absorption confirmed the presence of this triplet state, and helped inform the scientists about what was at work.

    “The peaks (in dye emission and UCNP absorption) matched almost exactly,” Cohen said.

    They then found that by increasing the concentration of lanthanide metals in the nanoparticles, from 22 percent to 52 percent, they could increase this triplet effect to improve the nanoparticles’ light-converting properties.

    “The metals are promoting dyes to their triplet states, which helps to explain both the efficiency of energy transfer and the instability of the dyes, since triplets tend to degrade in air,” Cohen said.

    The nanoparticles, which measure about 12 nanometers, or billionths of meters, across, could potentially be applied to the surface of solar cells to help them capture more light to convert into electricity, Schuck said.

    “The dyes act as molecular-scale solar concentrators, funneling energy from near-infrared photons into the nanoparticles,” Schuck said. Meanwhile, the particles themselves are largely transparent to visible light, so they would allow other usable light to pass through, he noted.

    Another potential use is to introduce the nanoparticles into cells to help label cell components for optical microscopy studies. They could be used for deep-tissue imaging, for example, or in optogenetics – a field that uses light to control cell activity.

    There are some roadblocks for researchers to overcome to realize these applications, Cohen said, as they are currently unstable and were studied in a nitrogen environment to avoid exposure to air.

    More R&D is needed to evaluate possible protective coatings for the particles, such as different polymers that serve to encapsulate the particles. “We have even better designs in mind going forward,” he said.

    The Molecular Foundry is a DOE Office of Science User Facility.

    Researchers from UC Berkeley, the Korea Research Institute of Chemical Technology, Sungkyunkwan University in South Korea, and the Kavli Energy NanoScience Institute at UC Berkeley also participated in this study. This work was supported by the DOE Office of Science; the National Science Foundation; the China Scholarship Council; and the Ministry of Science, Information and Communication Technology, and Future Planning of South Korea.

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  • richardmitnick 10:59 am on April 21, 2018 Permalink | Reply
    Tags: , How to bend and stretch a diamond, , , Nanotechnology   

    From MIT: “How to bend and stretch a diamond” 

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    April 19, 2018
    David L. Chandler

    (Stellar-Serbia/iStock) via Science Alert

    This scanning electron microscope image shows ultrafine diamond needles (cone shapes rising from bottom) being pushed on by a diamond tip (dark shape at top). These images reveal that the diamond needles can bend as much as 9 percent and still return to their original shape. Courtesy of the researchers.

    The brittle material can turn flexible when made into ultrafine needles, researchers find.

    Diamond is well-known as the strongest of all natural materials, and with that strength comes another tightly linked property: brittleness. But now, an international team of researchers from MIT, Hong Kong, Singapore, and Korea has found that when grown in extremely tiny, needle-like shapes, diamond can bend and stretch, much like rubber, and snap back to its original shape.

    The surprising finding is being reported this week in the journal Science, in a paper by senior author Ming Dao, a principal research scientist in MIT’s Department of Materials Science and Engineering; MIT postdoc Daniel Bernoulli; senior author Subra Suresh, former MIT dean of engineering and now president of Singapore’s Nanyang Technological University; graduate students Amit Banerjee and Hongti Zhang at City University of Hong Kong; and seven others from CUHK and institutions in Ulsan, South Korea.

    Experiment (left) and simulation (right) of a diamond nanoneedle being bent by the side surface of a diamond tip, showing ultralarge and reversible elastic deformation. No image credit.

    The results, the researchers say, could open the door to a variety of diamond-based devices for applications such as sensing, data storage, actuation, biocompatible in vivo imaging, optoelectronics, and drug delivery. For example, diamond has been explored as a possible biocompatible carrier for delivering drugs into cancer cells.

    The team showed that the narrow diamond needles, similar in shape to the rubber tips on the end of some toothbrushes but just a few hundred nanometers (billionths of a meter) across, could flex and stretch by as much as 9 percent without breaking, then return to their original configuration, Dao says.

    Ordinary diamond in bulk form, Bernoulli says, has a limit of well below 1 percent stretch. “It was very surprising to see the amount of elastic deformation the nanoscale diamond could sustain,” he says.

    “We developed a unique nanomechanical approach to precisely control and quantify the ultralarge elastic strain distributed in the nanodiamond samples,” says Yang Lu, senior co-author and associate professor of mechanical and biomedical engineering at CUHK. Putting crystalline materials such as diamond under ultralarge elastic strains, as happens when these pieces flex, can change their mechanical properties as well as thermal, optical, magnetic, electrical, electronic, and chemical reaction properties in significant ways, and could be used to design materials for specific applications through “elastic strain engineering,” the team says.

    The team measured the bending of the diamond needles, which were grown through a chemical vapor deposition process and then etched to their final shape, by observing them in a scanning electron microscope while pressing down on the needles with a standard nanoindenter diamond tip (essentially the corner of a cube). Following the experimental tests using this system, the team did many detailed simulations to interpret the results and was able to determine precisely how much stress and strain the diamond needles could accommodate without breaking.

    The researchers also developed a computer model of the nonlinear elastic deformation for the actual geometry of the diamond needle, and found that the maximum tensile strain of the nanoscale diamond was as high as 9 percent. The computer model also predicted that the corresponding maximum local stress was close to the known ideal tensile strength of diamond — i.e. the theoretical limit achievable by defect-free diamond.

    When the entire diamond needle was made of one crystal, failure occurred at a tensile strain as high as 9 percent. Until this critical level was reached, the deformation could be completely reversed if the probe was retracted from the needle and the specimen was unloaded. If the tiny needle was made of many grains of diamond, the team showed that they could still achieve unusually large strains. However, the maximum strain achieved by the polycrystalline diamond needle was less than one-half that of the single crystalline diamond needle.

    Yonggang Huang, a professor of civil and environmental engineering and mechanical engineering at Northwestern University, who was not involved in this research, agrees with the researchers’ assessment of the potential impact of this work. “The surprise finding of ultralarge elastic deformation in a hard and brittle material — diamond — opens up unprecedented possibilities for tuning its optical, optomechanical, magnetic, phononic, and catalytic properties through elastic strain engineering,” he says.

    Huang adds “When elastic strains exceed 1 percent, significant material property changes are expected through quantum mechanical calculations. With controlled elastic strains between 0 to 9 percent in diamond, we expect to see some surprising property changes.”

    The team also included Muk-Fung Yuen, Jiabin Liu, Jian Lu, Wenjun Zhang, and Yang Lu at the City University of Hong Kong; and Jichen Dong and Feng Ding at the Institute for Basic Science, in South Korea. The work was funded by the Research Grants Council of the Hong Kong Special Administrative Region, Singapore-MIT Alliance for Rresearch and Technology (SMART), Nanyang Technological University Singapore, and the National Natural Science Foundation of China.

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  • richardmitnick 10:19 am on April 5, 2018 Permalink | Reply
    Tags: A New State of Quantum Matter Has Been Found in a Material Scientists Thought Was All Chaos, Nanotechnology, Photoemission electron microscopy, , , , , Shakti geometry, Spin ice   

    From Science Alert: “A New State of Quantum Matter Has Been Found in a Material Scientists Thought Was All Chaos” 


    Science Alert

    5 APR 2018


    What else is lurking in there?

    Experiments carried out on a complex arrangement of magnetic particles have identified a completely new state of matter, and it can only be explained if scientists turn to quantum physics.

    The messy structures behind the research show strange properties that could allow us to study the chaos of exotic particles – if researchers can find order in there, it could help us understand these particles in greater detail, opening up a whole new landscape for quantum technology.

    Physicists from the US carried out their research on the geometrical arrangements of particles in a weird material known as spin ice.

    Like common old water ice, the particles making up spin ice sort themselves into geometric patterns as the temperature drops.

    There are a number of compounds that can be used to build this kind of material, but they all share the same kind of quantum property – their individual magnetic ‘spin’ sets up a bias in how the particles point to one another, creating complex structures.

    So, unlike the predictable crystalline patterns in water ice, the nanoscale magnetic particles making up spin ice can look disordered and chaotic under certain conditions, flipping back and forth wildly.

    The researchers focussed on one particular structure called a Shakti geometry, and measured how its magnetic arrangements fluctuated with changes in temperature.

    States of matter are usually broken down into categories such as solid, liquid, and gas. We’re taught on a fundamental level that a material’s volume and fluidity can change with shifts in its temperature and pressure.

    But there’s another way to think of a state of matter – by considering the points at which there’s a dramatic change in the way particles arrange themselves as they gain or lose energy.

    For example, the freezing of water is one such dramatic change – a sudden restructuring that occurs as pure water is chilled below 0 degrees Celsius (32 degrees Fahrenheit), where its molecules lose the energy they need to remain free and adopt another stable configuration.

    When researchers slowly lowered the temperature on spin ice arranged in a Shakti geometry, they got it to produce a similar behaviour – one that has never been seen before in other forms of spin ice.

    Using a process called photoemission electron microscopy, the team was then able to image the changes in pattern based on how their electrons emitted light.

    They were noticing points at which a specific arrangement persisted even as the temperature continued to drop.

    “The system gets stuck in a way that it cannot rearrange itself, even though a large-scale rearrangement would allow it to fall to a lower energy state,” says senior researcher Peter Schiffer, currently at Yale University.

    Such a ‘sticking point’ is a hallmark of a state of matter, and one that wasn’t expected in the flip-flopping madness of spin ice.

    Most states of matter can be described fairly efficiently using classical models of thermodynamics, with jiggling particles overcoming binding forces as they swap heat energy.

    In this case there was no clear model describing what was balancing the changes in energy with the material’s stable arrangement.

    So the team applied a quantum touch, looking at how entanglement between particles aligned to give rise to a particular topology, or pattern within a changing space.

    “Our research shows for the first time that classical systems such as artificial spin ice can be designed to demonstrate topological ordered phases, which previously have been found only in quantum conditions,” says physicist Cristiano Nisoli from Los Alamos National Laboratory.

    Ten years ago, quasiparticles that behaved like magnetic monopoles [Nature] were observed in another type of spin ice, also pointing at a weird kind of phase transition.

    Quasiparticles are becoming big things in our search for new kinds of matter that behaves in odd but useful ways, as they have pontential to be used in quantum computing. So having better models for understanding this quantum landscape will no doubt come in handy.

    This research was published in Nature.

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  • richardmitnick 7:26 am on April 5, 2018 Permalink | Reply
    Tags: , , , Nanotechnology   

    From JHU HUB: “With new technique, researchers create metallic alloy nanoparticles with unprecedented chemical capabilities” 

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    Rachel Wallach

    New, stable nanoparticles are expected to have useful applications in the chemical and energy industries. Image credit: Getty Images

    Johns Hopkins researchers have teamed with colleagues from three other universities to combine up to eight different metals into single, uniformly mixed nanoparticles, creating new and stable nanoparticles with useful applications in the chemical and energy industries, the researchers said.

    Metallic alloy nanoparticles—particles ranging from about a billionth to 100 billionths of a meter in size—are often used as catalysts in the production of industrial products such as fertilizers and plastics. Until now, only a small set of alloy nanoparticles have been available because of complications that arise when combining extremely different metals.

    In the March 30 cover article of the journal Science, the researchers reported that their new technique made it possible to combine multiple metals, including those not usually considered capable of mixing.

    “This method enables new combinations of metals that do not exist in nature and do not otherwise go together,” said Chao Wang, an assistant professor in the Department of Chemical and Biomolecular Engineering at Johns Hopkins and one of the study’s co-authors.

    The new materials, known as high-entropy-alloy nanoparticles, have created unprecedented catalytic mechanisms and reaction pathways and are expected to improve energy efficiency in the manufacturing process and lower production costs.

    The new method uses shock waves to heat the metals to extremely high temperatures—2,000 degrees Kelvin (more than 3,140 Fahrenheit) and higher—at exceptionally rapid rates, both heating and cooling them in the span of milliseconds. The metals are melted together to form small droplets of liquid solutions at the high temperatures and are then rapidly cooled to form homogeneous nanoparticles. Traditional methods, which rely on relatively slow and low-temperature heating and cooling techniques, often result in clumps of metal instead of separate particles.

    Based on these new nanoparticles, Wang’s research group designed a five-metal nanoparticle that demonstrated superior catalytic performance for selective oxidation of ammonia to nitrogen oxide, a reaction used by the chemical industry to produce nitric acid, which is used in the large-scale production of fertilizers and other products.

    In addition to nitric acid production, the researchers are exploring use of the nanoparticles in reactions like the removal of nitrogen oxide from vehicle exhaust. The work in Wang’s lab was part of a collaboration with colleagues from the University of Maryland, College Park; the University of Illinois at Chicago; and MIT.

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    About the Hub

    We’ve been doing some thinking — quite a bit, actually — about all the things that go on at Johns Hopkins. Discovering the glue that holds the universe together, for example. Or unraveling the mysteries of Alzheimer’s disease. Or studying butterflies in flight to fine-tune the construction of aerial surveillance robots. Heady stuff, and a lot of it.

    In fact, Johns Hopkins does so much, in so many places, that it’s hard to wrap your brain around it all. It’s too big, too disparate, too far-flung.

    We created the Hub to be the news center for all this diverse, decentralized activity, a place where you can see what’s new, what’s important, what Johns Hopkins is up to that’s worth sharing. It’s where smart people (like you) can learn about all the smart stuff going on here.

    At the Hub, you might read about cutting-edge cancer research or deep-trench diving vehicles or bionic arms. About the psychology of hoarders or the delicate work of restoring ancient manuscripts or the mad motor-skills brilliance of a guy who can solve a Rubik’s Cube in under eight seconds.

    There’s no telling what you’ll find here because there’s no way of knowing what Johns Hopkins will do next. But when it happens, this is where you’ll find it.

    Johns Hopkins Campus

    The Johns Hopkins University opened in 1876, with the inauguration of its first president, Daniel Coit Gilman. “What are we aiming at?” Gilman asked in his installation address. “The encouragement of research … and the advancement of individual scholars, who by their excellence will advance the sciences they pursue, and the society where they dwell.”

    The mission laid out by Gilman remains the university’s mission today, summed up in a simple but powerful restatement of Gilman’s own words: “Knowledge for the world.”

    What Gilman created was a research university, dedicated to advancing both students’ knowledge and the state of human knowledge through research and scholarship. Gilman believed that teaching and research are interdependent, that success in one depends on success in the other. A modern university, he believed, must do both well. The realization of Gilman’s philosophy at Johns Hopkins, and at other institutions that later attracted Johns Hopkins-trained scholars, revolutionized higher education in America, leading to the research university system as it exists today.

  • richardmitnick 1:31 pm on March 29, 2018 Permalink | Reply
    Tags: , Inelastic neutron scattering, Nanomagnets, Nanotechnology, , , , , The possibility of producing qubits from organometallic molecules with a single magnetic ion in each molecule   

    From Niels Bohr Institute: “Neutron scattering brings us a step closer to the quantum computer” 

    Niels Bohr Institute bloc

    Niels Bohr Institute

    29 March 2018

    Mikkel Agerbæk Sørensen,
    Ph.D.-student, Department of Chemistry, University of Copenhagen

    Ursula Bengård Hansen,
    Postdoc, X-ray and Neutron Science
    Niels Bohr Institute, University of Copenhagen
    +45 60 47 86 15

    Kim Lefmann,
    Lektor, X-ray and Neutron Science
    Niels Bohr Institute, University of Copenhagen
    +45 29 25 04 76

    Jesper Bendix,
    Professor, Kemisk Institut, University of Copenhagen
    +45 35 32 01 01

    Quantum computers:

    A major challenge for future quantum computers is that you have to keep the quantum information long enough to make calculations on it – but the information only has a very short lifespan, often less than a microsecond. Now researchers at the Niels Bohr Institute and the Department of Chemistry at the University of Copenhagen, in collaboration with a team of international researchers, have come closer to a solution. The results are published in the renowned journal Nature Communications.

    PhD student Mikkel Agerbæk Sørensen from the Department of Chemistry and Postdoc Ursula Bengård Hansen from the research group X-ray and Neutron Science at the Niels Bohr Institute shows a 3D model of the studied molecule. By making small changes in the form of the molecule, the tunnelling can be suppressed. In the background Associate Professor Kim Lefmann and Professor Jesper Bendix. Photo: Ola J. Joensen.

    In order to build the quantum computer of the future, you need to be able to store the quantum information – what we call “quantum bits” or “qubits” – (which corresponds to bits and bytes in a traditional computer). Several research groups are experimenting with different ideas for how this can be done in practice.

    A team of chemists and physicists from the Niels Bohr Institute and the Department of Chemistry at the University of Copenhagen, as well as collaborators from Germany, France, Switzerland, Spain and the United States, have studied the possibility of producing qubits from organometallic molecules with a single magnetic ion in each molecule.

    In these “nanomagnets” there is the particular challenge that random movements in the outside world can interfere with the magnetic ions, so that the quantum information is lost before you can manage to perform calculations with it. Even at ultra-low temperatures just above absolute zero (0.05 Kelvin), where all motion “normally” stops, the system can still be subjected to quantum mechanical disturbances, also known as “tunnelling”.

    Mikkel Agerbæk Sørensen, who is the first author of the study, explains that suppressing the tunnelling is considered one of the greatest challenges in the production of new nanomagnets with actual application possibilities: “there are several theoretical models for how to suppress the tunnelling in such molecule-based magnets. With this study, we are the first to have been able to prove the leading model experimentally.”

    Changes in the form of the molecule are part of the solution

    There is still a long way to go to be able to use these nanomagnets in a practical quantum computer, but the researchers have now discovered another “control lever”, namely the geometric form of the molecule that can be used to get closer to the goal. With the construction of the largest neutron facility (ESS) in Lund, Sweden, researchers will have better opportunities to measure and understand tunnelling, thus getting closer to controlling it – and ultimately pave the way for quantum computing.

    In order to understand the quantum behavior of a molecule-based magnet, it is necessary to measure the energy levels of the molecule very accurately. This is best done with the so-called inelastic neutron scattering. Such experiments can only be done using instruments located at major international research facilities. With the performance of ESS, researchers at the University of Copenhagen will have even better opportunities to conduct such studies. Here Mikkel Agerbæk Sørensen at the entrance of the instrument IN6 at the Institute Laue-Langevin in Grenoble.

    See the full article here .

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    Niels Bohr Institute Campus

    The Niels Bohr Institute (Danish: Niels Bohr Institutet) is a research institute of the University of Copenhagen. The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics and biophysics.

    The Institute was founded in 1921, as the Institute for Theoretical Physics of the University of Copenhagen, by the Danish theoretical physicist Niels Bohr, who had been on the staff of the University of Copenhagen since 1914, and who had been lobbying for its creation since his appointment as professor in 1916. On the 80th anniversary of Niels Bohr’s birth – October 7, 1965 – the Institute officially became The Niels Bohr Institute.[1] Much of its original funding came from the charitable foundation of the Carlsberg brewery, and later from the Rockefeller Foundation.[2]

    During the 1920s, and 1930s, the Institute was the center of the developing disciplines of atomic physics and quantum physics. Physicists from across Europe (and sometimes further abroad) often visited the Institute to confer with Bohr on new theories and discoveries. The Copenhagen interpretation of quantum mechanics is named after work done at the Institute during this time.

    On January 1, 1993 the institute was fused with the Astronomic Observatory, the Ørsted Laboratory and the Geophysical Institute. The new resulting institute retained the name Niels Bohr Institute.

  • richardmitnick 12:41 pm on March 27, 2018 Permalink | Reply
    Tags: , CNSI - California NanoSystems Institute, Magnify, Nanotechnology,   

    From UCLA Newsroom: “UCLA incubator helps drive innovations, assisting early-stage tech and life science companies” 

    UCLA Newsroom

    March 26, 2018
    Meghan Steele Horan

    Magnify at CNSI provides startup companies, like Octant, with the necessary tools and space to perform hands-on research and development to advance their product. Marc Roseboro/CNSI

    Dr. Chia Soo’s professional life has been dedicated to finding new and innovative treatments to promote skin regeneration for scars from burns or other skin trauma. While performing research at UCLA more than 20 years ago, she found a promising peptide drug for wound healing and eventually founded her own company. But before she could bring it to market, she would need to perform preclinical proof of concept studies, which for her, would require more laboratory space, access to specialized and expensive facilities, and a place to grow her business.

    For Soo, a solution was two buildings away at UCLA’s deep technology incubator called Magnify. Deep technology innovations are those built around unique, protected or hard-to-reproduce technological or scientific advances and pertain to a variety of industries including life sciences, energy, information technology and materials.

    “Magnify was directly responsible for us securing $8 million in Small Business Innovation Research grant funding from the National Institutes of Health to perform preclinical trials,” said Soo, professor and vice chair for research in the division of plastic and reconstructive surgery at the David Geffen School of Medicine at UCLA and founder of Scarless Laboratories. “What Magnify offered was not just a place or a desk, but access to millions of dollars in resources and facilities due to its proximity to the California NanoSystems Institute and UCLA. In order to prove that our drug worked, we needed facilities to be able to do high level research.”

    Scarless Laboratories is an early-stage biotechnology company which has recently completed preclinical trials on a peptide drug for wound healing that could make wound tissue stronger as it heals, or more difficult to rip apart. It could also make wounds heal faster while reducing scarring. This could benefit people suffering from chronic wounds like diabetic ulcers or those undergoing elective surgeries. Scarless is now in the process of submitting an application for Phase I clinical trials, an initial phase of testing that assesses the safety of a drug in a small number of volunteers.

    Housed right on the UCLA campus inside the California NanoSystems Institute, Magnify (formerly known as the CNSI Incubator), helps startups succeed by providing access to high-end scientific equipment and entrepreneurial networking opportunities to reduce the time and money needed to launch. According to a 2017 Milken Institute Report, UCLA attracted more than $1 billion in research funding and also ranks no. 1 in the nation for spinning out companies based on campus research.

    “As one of the world’s top research universities, UCLA has the intellectual capital, infrastructure and sophisticated tools needed to transform ideas into commercial products that will improve peoples’ quality of life around the world,” said Brian Benson, who oversees Magnify as director of entrepreneurship and commercialization at CNSI.

    Magnify at CNSI features state-of-the-art co-working laboratory and office space as well as other critical services and support. Marc Roseboro/CNSI.

    The institute’s members include more than 150 faculty members from 35 departments across UCLA. This diversity of expertise and backgrounds provides a network that fosters powerful collaborations among scientists and researchers from applied mathematics and engineering to the natural and biomedical sciences. Research members from CNSI are involved with almost half of UCLA startups.

    The infrastructure of CNSI offers startup companies access to a collection of advanced instrumentation from the six state-of-the-art CNSI Technology Centers, some of which include optical, electron and scanning probe microscopy, cleanroom fabrication, and tools for analyzing nanomaterials.

    Membership in Magnify offers highly motivated entrepreneurs the ability to conduct key activities like conducting proof-of-concept experiments or building a prototype. This is important for collecting critical data that will inform the design of a final commercial product.

    “Our goal is to help companies reduce the time and capital needed to transform their ideas into a scalable, fundable business,” Benson said. “Magnify provides critical resources including mentorship, business development, and funding advice that can lead to a company’s success.”

    To be eligible for the incubator, companies should have sufficient working capital to achieve critical technical and business milestones such as Series A financing. This type of funding enables development of a commercially viable prototype, while covering incubator fees — which would vary from company to company based on needs — for at least six months. In addition, companies should also be incorporated for less than five years and have an established residence in the incubator.

    Startups in the greater Los Angeles area are encouraged to apply, but preferences will be given to companies with a UCLA affiliation which includes a license of intellectual property owned or controlled by UCLA, sponsored research agreement with UCLA, one active member — either a cofounder or member of the management team — who is a current UCLA faculty, student, staff or alumnus.

    Millibatt, a company co-founded by two UCLA alumni, makes millimeter-scale-sized, rechargeable lithium-ion batteries for items including wearable and medical devices like fitness trackers or pacemakers. At the time of their invention, Leland Smith was pursuing a Ph.D. and Janet Hur was a postdoctoral researcher, both in materials science and engineering. Smith and Hur filed a UCLA provisional patent, formed their company and joined Magnify in late 2016.

    “Right now, we’re building out a small pilot line using CNSI’s facilities as a proof-of-concept for a larger pilot line when we leave the incubator,” Smith said. “Using this pilot line, we’re trying to demonstrate that we could build about 1 million batteries a year.”

    What many young entrepreneurs may not think about is how they will access equipment and order necessary materials for experiments or building prototypes.

    “There are so many things to think about. Where can you get a fume hood, time on an electron microscope, or store chemical waste?” Smith said. “If we had to do things like this on our own without CNSI and Magnify, it easily would have added months of complications for us.”

    Admission to Magnify is through a competitive review process starting with an online application that is initially screened by the Magnify team. Selected applicants are invited to present to the Magnify advisory committee, on a quarterly basis. Acceptance decisions are made by the Magnify director along with input from the advisory committee.

    Magnify is always looking for great startups developing transformative technology to join the innovation ecosystem. If you are a passionate entrepreneur looking to launch a company we encourage you to apply today.

    See the full article here .

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    UC LA Campus

    For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

    We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

    This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

  • richardmitnick 3:39 pm on March 22, 2018 Permalink | Reply
    Tags: Laser Fusion at the Microscale, Nanotechnology, ,   

    From Optics & Photonics: “Laser Fusion at the Microscale” 

    Optics & Photonics

    Scanning electron micrograph (a) of deuterated-polyethylene nanowires used in experiments, and numerical simulations (b-d) of those nanowires exploding under the influence of ultra-intense laser pulse. [Image: Advanced Beam Laboratory/CSU]

    Stewart Wills

    The words “laser fusion” conjure up vast, megajoule laser installations housed in football-field-sized buildings, such as the U.S. National Ignition Facility (see Laser fusion: The uncertain road to ignition, OPN, September 2014). But researchers from the United States and Germany, led by OSA Fellow Jorge Rocca of Colorado State University, recently managed to churn out micro-scale fusion reactions using much more modest equipment. Their setup: a 1-J, tabletop femtosecond laser built from scratch—with a dense array of polyethylene nanowires serving as the fusion target (see Nat. Commun., https://www.nature.com/articles/s41467-018-03445-z).

    The team believes that its recipe could offer a good source of pulses of bright, near-monoenergetic neutrons for some imaging and materials-science applications. And the ability to create extreme plasmas with a compact laser, the researchers suggest, could open interesting windows into high-energy-density science.

    Nanowire forest

    The research team (including scientists from Colorado State University and the Nevada National Security Site, USA, and the Institut für Theoretische Physik, Germany) began its setup by creating 12.5-mm diameter arrays of vertical, 200-nm- and 400-nm-diameter and 5-micron-long nanowires as fusion targets. The wires were made of deuterated polyethylene (CD2), a polymer in which deuterium (so-called heavy hydrogen), with a nucleus including one proton and one neutron, substitutes for ordinary hydrogen, which includes one proton only.

    The researchers arrayed the vertical nanowires on a 200-micron-thick substrate of solid CD2, packing in the wires with sufficient interstitial space to make the array’s density 16 to 19 percent of the density of the solid polymer. That created a “near-solid-density” medium to serve as the target.

    Next, the scientists used a frequency-doubled, 400-nm chirped-pulse amplification Ti:sapphire laser to generate 60-fs laser pulses with total energies of around 1.65 J, and aimed that stream of pulses at the nanowire-forest samples. They focused the pulses into a spot 2 to 2.6 microns in diameter, thereby creating intensities on the order of 1020 W/cm^2 on the target.

    From plasma to fusion

    According to the researchers, the vacant spaces around the nanowires let the energy from the relativistic-intensity laser pulses penetrate deep inside the nanowire structure, where it becomes trapped and “practically totally absorbed.” The absorbed energy rips electrons off of the nanowire surface and accelerates them to high velocities, at which they interact with the nanowires and cause them to explode into a void-filling plasma. Within that plasma, the electron-stripped deuterium nuclei, or deuterons, achieve kinetic energies on the order of 3 MeV. Those energies drive deuteron-deuteron fusion reactions that create streams of neutrons, with a characteristic energy of 2.45 MeV, as by-products.

    In experiments with the nanowire targets, the team found that it could produce fluxes of 2.45-MeV, fusion-generated neutrons some 500 times larger than experiments using flat, solid CD2 targets. The team claims that the observed 2 × 106 neutrons per joule is “the largest D–D fusion neutron yield reported to date for plasmas generated by laser pulse energies in the 1 J range.” And numerical simulations suggest that relatively small increases in laser pulse energy could significantly increase the fusion neutron yield.

    The repetition-rate advantage

    A particular strength of the setup, according to the researchers, is the compact laser’s ability to pump out femtosecond pulses at a high repetition rate, compared with the Hz-scale or slower rates of petawatt-class lasers. The creation of a target that can achieve fusion with these lower-energy, high-repetition-rate lasers, the researchers suggest, is “of significant interest” for high-energy-density science, such as studies of conditions in the cores of stars.

    On a more applied note, the team suggests that its approach using nanowire arrays could allow the creation of efficient point sources of quasi-monoenergetic neutrons for neutron imaging and tomography, neutron diffraction studies in materials science, and other uses.

    See the full article here .

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    Optics & Photonics News (OPN) is The Optical Society’s monthly news magazine. It provides in-depth coverage of recent developments in the field of optics and offers busy professionals the tools they need to succeed in the optics industry, as well as informative pieces on a variety of topics such as science and society, education, technology and business. OPN strives to make the various facets of this diverse field accessible to researchers, engineers, businesspeople and students. Contributors include scientists and journalists who specialize in the field of optics. We welcome your submissions.

  • richardmitnick 8:44 am on March 7, 2018 Permalink | Reply
    Tags: , A treasure trove for nanotechnology experts, , , Nanotechnology   

    From EPFL: “A treasure trove for nanotechnology experts” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne

    Sarah Perrin

    EPFL scientists identified more than 1000 2D materials. ©EPFL/G.Pizzi

    A team from EPFL and NCCR Marvel has identified more than 1,000 materials with a particularly interesting 2D structure. Their research, which made the cover page of Nature Nanotechnology, paves the way for groundbreaking technological applications.


    2D materials, which consist of a few layers of atoms, may well be the future of nanotechnology. They offer potential new applications and could be used in small, higher-performance and more energy-efficient devices. 2D materials were first discovered almost 15 years ago, but only a few dozen of them have been synthesized so far. Now, thanks to an approach developed by researchers from EPFL’s Theory and Simulation of Materials Laboratory (THEOS) and from NCCR-MARVEL for Computational Design and Discovey of Novel Materials, many more promising 2D materials may now be identified. Their work was recently published in the journal Nature Nanotechnology, and even got a mention on the cover page.

    The first 2D material to be isolated was graphene, in 2004, earning the researchers who discovered it a Nobel Prize in 2010. This marked the start of a whole new era in electronics, as graphene is light, transparent and resilient and, above all, a good conductor of electricity. It paved the way to new applications in numerous fields such as photovoltaics and optoelectronics.

    “To find other materials with similar properties, we focused on the feasibility of exfoliation,” explains Nicolas Mounet, a researcher in the THEOS lab and lead author of the study. “But instead of placing adhesive strips on graphite to see if the layers peeled off, like the Nobel Prize winners did, we used a digital method.”

    More than 100,000 materials analyzed

    The researchers developed an algorithm to review and carefully analyze the structure of more than 100,000 3D materials recorded in external databases. From this, they created a database of around 5,600 potential 2D materials, including more than 1,000 with particularly promising properties. In other words, they’ve created a treasure trove for nanotechnology experts.

    To build their database, the researchers used a step-by-step process of elimination. First, they identified all of the materials that are made up of separate layers. “We then studied the chemistry of these materials in greater detail and calculated the energy that would be needed to separate the layers, focusing primarily on materials where interactions between atoms of different layers are weak, something known as Van der Waals bonding,” says Marco Gibertini, a researcher at THEOS and the second author of the study.

    A plethora of 2D candidates

    Of the 5,600 materials initially identified, the researchers singled out 1,800 structures that could potentially be exfoliated, including 1,036 that looked especially easy to exfoliate. This represents a considerable increase in the number of possible 2D materials known today. They then selected the 258 most promising materials, categorizing them according to their magnetic, electronic, mechanical, thermal and topological properties.

    “Our study demonstrates that digital techniques can really boost discoveries of new materials,” says Nicola Marzari, the director of NCCR Marvel and a professor at THEOS. “In the past, chemists had to start from scratch and just keep trying different things, which required hours of lab work and a certain amount of luck. With our approach, we can avoid this long, frustrating process because we have a tool that can single out the materials that are worth studying further, allowing us to conduct more focused research.”

    It is also possible to reproduce the researchers’ calculations thanks to their software AiiDA, which describes the calculation process for each material discovered in the form of workflows and stores the full provenance of each stage of the calculation. “Without AiiDA, it would have been very difficult to combine and process different types of data,” explains Giovanni Pizzi, a senior researcher at THEOS and co-author of the study. “Our workflows are available to the public, so anyone in the world can reproduce our calculations and apply them to any material to find out if it can be exfoliated.”

    See the full article here .

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    EPFL campus

    EPFL is Europe’s most cosmopolitan technical university. It receives students, professors and staff from over 120 nationalities. With both a Swiss and international calling, it is therefore guided by a constant wish to open up; its missions of teaching, research and partnership impact various circles: universities and engineering schools, developing and emerging countries, secondary schools and gymnasiums, industry and economy, political circles and the general public.

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