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  • richardmitnick 10:25 am on February 24, 2020 Permalink | Reply
    Tags: "Helix of an Elusive Rare Earth Metal Could Help Push Moore's Law to The Next Level", , , Nanotechnology, , Rare earth metal Tellurium, , , The tellurium helix slip neatly inside a nanotube of boron nitride., Transistors   

    From Purdue University via Science Alert: “Helix of an Elusive Rare Earth Metal Could Help Push Moore’s Law to The Next Level” 

    From Purdue University

    via

    ScienceAlert

    Science Alert

    23 FEB 2020
    MIKE MCRAE

    1
    Tellurium helix (Qin et al., Nature Electronics, 2020)

    To cram ever more computing power into your pocket, engineers need to come up with increasingly ingenious ways to add transistors to an already crowded space.

    Unfortunately there’s a limit to how small you can make a wire. But a twisted form of rare earth metal just might have what it takes to push the boundaries a little further.

    A team of researchers funded by the US Army have discovered a way to turn twisted nanowires of one of the rarest of rare earth metals, tellurium, into a material with just the right properties that make it an ideal transistor at just a couple of nanometres across.

    “This tellurium material is really unique,” says Peide Ye, an electrical engineer from Purdue University.

    “It builds a functional transistor with the potential to be the smallest in the world.”

    Transistors are the work horse of anything that computes information, using tiny changes in charge to prevent or allow larger currents to flow.

    Typically made of semiconducting materials, they can be thought of as traffic intersections for electrons. A small voltage change in one place opens the gate for current to flow, serving as both a switch and an amplifier.

    Combinations of open and closed switches are the physical units representing the binary language underpinning logic in computer operations. As such, the more you have in one spot, the more operations you can run.

    Ever since the first chunky transistor was prototyped a little more than 70 years ago, a variety of methods and novel materials have led to regular downsizing of the transistor.

    In fact the shrinking was so regular that co-founder of the computer giant Intel, George Moore, famously noted in 1965 that it would follow a trend of transistors doubling in density every two years.

    Today, that trend has slowed considerably. For one thing, more transistors in one spot means more heat building up.

    But there are also only so many ways you can shave atoms from a material and still have it function as a transistor. Which is where tellurium comes in.

    Though not exactly a common element in Earth’s crust, it’s a semi-metal in high demand, finding a place in a variety of alloys to improve hardness and help it resist corrosion.

    It also has properties of a semiconductor; carrying a current under some circumstances and acting as a resistor under others.

    Curious about its characteristics on a nanoscale, engineers grew single-dimensional chains of the element and took a close look at them under an electron microscope. Surprisingly, the super-thin ‘wire’ wasn’t exactly a neat line of atoms.

    “Silicon atoms look straight, but these tellurium atoms are like a snake. This is a very original kind of structure,” says Ye.

    On closer inspection they worked out that the chain was made of pairs of tellurium atoms bonded strongly together, and then stacking into a crystal form pulled into a helix by weaker van der Waal forces.

    Building any kind of electronics from a crinkly nanowire is just asking for trouble, so to give the material some structure the researchers went on the hunt for something to encapsulate it in.

    The solution, they found, was a nanotube of boron nitride. Not only did the tellurium helix slip neatly inside, the tube acted as an insulator, ticking all the boxes that would make it suit life as a transistor.

    Most importantly, the whole semiconducting wire was a mere 2 nanometres across, putting it in the same league as the 1 nanometre record set a few years ago.

    Time will tell if the team can squeeze it down further with fewer chains, or even if it will function as expected in a circuit.

    If it works as hoped, it could contribute to the next generation of miniaturised electronics, potentially halving the size of current cutting edge microchips.

    “Next, the researchers will optimise the device to further improve its performance, and demonstrate a highly efficient functional electronic circuit using these tiny transistors, potentially through collaboration with ARL researchers,” says Joe Qiu, program manager for the Army Research Office.

    Even if the concept pans out, there’s a variety of other challenges for shrinking technology to overcome before we’ll find it in our pockets.

    While tellurium isn’t currently considered to be a scarce resource, in spite of its relative rarity, it could be in high demand in future electronics such as solar cells.

    This research was published in Nature Electronics.

    See the full article here .

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    Purdue University is a public research university in West Lafayette, Indiana, and the flagship campus of the Purdue University system. The university was founded in 1869 after Lafayette businessman John Purdue donated land and money to establish a college of science, technology, and agriculture in his name. The first classes were held on September 16, 1874, with six instructors and 39 students.

    The main campus in West Lafayette offers more than 200 majors for undergraduates, over 69 masters and doctoral programs, and professional degrees in pharmacy and veterinary medicine. In addition, Purdue has 18 intercollegiate sports teams and more than 900 student organizations. Purdue is a member of the Big Ten Conference and enrolls the second largest student body of any university in Indiana, as well as the fourth largest foreign student population of any university in the United States.

     
  • richardmitnick 1:29 pm on February 22, 2020 Permalink | Reply
    Tags: "Time-resolved measurement in a memory device", , Data can be stored in magnetic tunnel junctions virtually without any error and in less than a nanosecond., , , Nanotechnology, , The researchers replaced the isolated metal dot by a magnetic tunnel junction., Tomorrow’s memory devices   

    From ETH Zürich: “Time-resolved measurement in a memory device” 

    ETH Zurich bloc

    From ETH Zürich

    19.02.2020
    Oliver Morsch

    Researchers at ETH have measured the timing of single writing events in a novel magnetic memory device with a resolution of less than 100 picoseconds. Their results are relevant for the next generation of main memories based on magnetism.

    1
    The chip produced by IMEC for the experiments at ETH. The tunnel junctions used to measure the timing of the magnetisation reversal are located at the centre (Image courtesy of IMEC).

    At the Department for Materials of the ETH in Zürich, Pietro Gambardella and his collaborators investigate tomorrow’s memory devices. They should be fast, retain data reliably for a long time and also be cheap. So-​called magnetic “random access memories” (MRAM) achieve this quadrature of the circle by combining fast switching via electric currents with durable data storage in magnetic materials. A few years ago researchers could already show that a certain physical effect – the spin-​orbit torque – makes particularly fast data storage possible. Now Gambardella’s group, together with the R&D-​centre IMEC in Belgium, managed to temporally resolve the exact dynamics of a single such storage event – and to use a few tricks to make it even faster.

    Magnetising with single spins

    To store data magnetically, one has to invert the direction of magnetisation of a ferromagnetic (that is, permanently magnetic) material in order to represent the information as a logic value, 0 or 1. In older technologies, such as magnetic tapes or hard drives, this is achieved through magnetic fields produced inside current-​carrying coils. Modern MRAM-​memories, by contrast, directly use the spins of electrons, which are magnetic, much like small compass needles, and flow directly through a magnetic layer as an electric current. In Gambardella’s experiments, electrons with opposite spin directions are spatially separated by the spin-​orbit interaction. This, in turn, creates an effective magnetic field, which can be used to invert the direction of magnetisation of a tiny metal dot.

    “We know from earlier experiments, in which we stroboscopically scanned a single magnetic metal dot with X-​rays, that the magnetisation reversal happens very fast, in about a nanosecond”, says Eva Grimaldi, a post-​doc in Gambardella’s group. “However, those were mean values averaged over many reversal events. Now we wanted to know how exactly a single such event takes place and to show that it can work on an industry-​compatible magnetic memory device.”

    Time resolution through a tunnel junction

    2
    Electron microscope image of the magnetic tunnel junction (MTJ, at the centre) and of the electrodes for controlling and measuring the reversal process. (Image: P. Gambardella / ETH Zürich)

    To do so, the researchers replaced the isolated metal dot by a magnetic tunnel junction. Such a tunnel junction contains two magnetic layers separated by an insulation layer that is only one nanometre thick. Depending on the spin direction – along the magnetisation of the magnetic layers, or opposite to it – the electrons can tunnel through that insulating layer more or less easily. This results in an electrical resistance that depends on the alignment of the magnetization in one layer with respect to the other and thus represents “0” and “1”. From the time dependence of that resistance during a reversal event, the researchers could reconstruct the exact dynamics of the process. In particular, they found that the magnetisation reversal happens in two stages: an incubation stage, during which the magnetisation stays constant, and the actual reversal stage, which lasts less than a nanosecond.

    3
    The magnetic tunnel junction (yellow and red disks) in which the magnetisation of the red disk is inverted by electron spins (blue and yellow arrows). The reversal process is measured through the tunnel resistance (vertical blue arrows).

    Small fluctuations

    “For a fast and reliable memory device it is essential that the time fluctuations between the individual reversal events are minimized”, explains Gambardella’s PhD student Viola Krizakova. So, based on their data the scientists developed a strategy to make those fluctuations as small as possible. To that end, they changed the current pulses used to control the magnetisation reversal in such a way as to introduce two additional physical phenomena. The so-​called spin-​transfer torque as well as a short voltage pulse during the reversal stage now resulted in a reduction of the total time for the reversal event to less than 0,3 nanoseconds, with temporal fluctuations of less than 0,2 nanoseconds.

    Application-​ready technology

    “Putting all of this together, we have found a method whereby data can be stored in magnetic tunnel junctions virtually without any error and in less than a nanosecond”, says Gambardella. Moreover, the collaboration with the research centre IMEC made it possible to test the new technology directly on an industry-​compatible wafer. Kevin Garello, a former post-​doc from Gambardella’s lab, produced the chips containing the tunnel contacts for the experiments at ETH and optimized the materials for them. In principle, the technology would, therefore, be immediately ready for use in a new generation of MRAM.

    Gambardella stresses that MRAM memories are particularly interesting because, differently from conventional main memories such as SRAM or DRAM, they don’t lose their information when the computer is switched off, but are still equally fast. He concedes, though, that the market for MRAM memories currently does not demand such high writing speeds since other technical bottlenecks such as power losses caused by large switching currents limit the access times. In the meantime, he and his co-​workers are already planning further improvements: they want to shrink the tunnel junctions and use different materials that use current more efficiently.

    Science paper:
    “Grimaldi E, et al. Single-​shot dynamics of spin–orbit torque and spin transfer torque switching in three-​terminal magnetic tunnel junctions.”
    Nature Nanotechnology

    See the full article here .

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    Please help promote STEM in your local schools.

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    ETH Zurich campus
    ETH Zürich is one of the leading international universities for technology and the natural sciences. It is well known for its excellent education, ground-breaking fundamental research and for implementing its results directly into practice.

    Founded in 1855, ETH Zürich today has more than 18,500 students from over 110 countries, including 4,000 doctoral students. To researchers, it offers an inspiring working environment, to students, a comprehensive education.

    Twenty-one Nobel Laureates have studied, taught or conducted research at ETH Zürich, underlining the excellent reputation of the university.

     
  • richardmitnick 9:50 am on February 18, 2020 Permalink | Reply
    Tags: "Generating electricity 'out of thin air'", Air-gen, , , , , Nanotechnology, , Using a natural protein to create electricity from moisture in the air.   

    From UMass Amherst via COSMOS Magazine: “Generating electricity ‘out of thin air'” 

    U Mass Amherst

    From UMass Amherst

    via

    Cosmos Magazine bloc

    COSMOS Magazine

    18 February 2020
    Nick Carne

    Researchers unveil a new device powered by a microbe.

    1
    Graphic image of a thin film of protein nanowires generating electricity from atmospheric humidity. UMass Amherst/Yao and Lovley labs.

    Scientists in the US have developed a device they say uses a natural protein to create electricity from moisture in the air.

    Writing in the journal Nature, electrical engineer Jun Yao and microbiologist Derek Lovley, from the University of Massachusetts Amherst, introduce the Air-gen (or air-powered generator), which Lovley describes as “the most amazing and exciting application of protein nanowires yet”.

    Air-Gen has electrically conductive protein nanowires produced by the microbe Geobacter, which Lovley discovered in the Potomac River three decades ago and has been working with ever since, in particular investigating its potential for “green electronics”.

    The Air-gen connects electrodes to the protein nanowires in such a way that electrical current is generated from the water vapour naturally present in the atmosphere.

    It requires only a thin film of protein nanowires less than 10 microns thick. The bottom of the film rests on an electrode, while a smaller electrode that covers only part of the nanowire film sits on top.

    The film adsorbs water vapour from the atmosphere. A combination of the electrical conductivity and surface chemistry of the protein nanowires, coupled with the fine pores between the nanowires within the film, establishes the conditions that generate an electrical current between the two electrodes.

    Developed in Yao’s lab, Air-gen is low-cost, non-polluting and renewable, and needs neither sun nor wind, the researchers say. It can work indoors, or in extremely low humidity of the desert.

    The current generation can power only small electronics, but they hope to bring it to commercial scale soon. Beyond that is the idea a small Air-gen “patch” that can power electronic wearables such as health and fitness monitors and smart watches. And then, maybe, there are mobile phones.

    “The ultimate goal is to make large-scale systems,” says Yao. “For example, the technology might be incorporated into wall paint that could help power your home. Or, we may develop stand-alone air-powered generators that supply electricity off the grid.”

    Lovley also is working to improve the practical biological capabilities of Geobacter. His lab recently developed a new microbial strain to more rapidly and inexpensively mass produce protein nanowires.

    “We turned E. coli into a protein nanowire factory,” he says. “With this new scalable process, protein nanowire supply will no longer be a bottleneck to developing these applications.”

    The Royal Institution of Australia has an education resource based on this article.
    You can access it here.

    See the full article here .

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    John Schaefer


    For new music by living composers

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    Please visit The Jazz Loft Project based on the work of Sam Stephenson
    Please visit The Jazz Loft Radio project from New York Public Radio

    U Mass Amherst campus

    UMass Amherst, the Commonwealth’s flagship campus, is a nationally ranked public research university offering a full range of undergraduate, graduate and professional degrees.

    As the flagship campus of America’s education state, the University of Massachusetts Amherst is the leader of the public higher education system of the Commonwealth, making a profound, transformative impact to the common good. Founded in 1863, we are the largest public research university in New England, distinguished by the excellence and breadth of our academic, research and community outreach programs. We rank 29th among the nation’s top public universities, moving up 11 spots in the past two years in the U.S. News & World Report’s annual college guide.

     
  • richardmitnick 2:48 pm on February 10, 2020 Permalink | Reply
    Tags: "Quantum technologies: New insights into superconducting processes", , Carsten Schuck's research group at Münster University has been working for several years on developing such single-photon detectors based on superconductors., Forschungszentrum Jülich, High temperature superconducting microbridge, Nanotechnology, , , University of Münster   

    From University of Münster: “Quantum technologies: New insights into superconducting processes” 

    1

    From University of Münster

    10. February 2020

    1
    Measurement setup for the characterization of microbridges in a cryostat

    Physicists demonstrate energy quantization in high-temperature superconductors / Study in “Nature Communications”

    The development of a quantum computer that can solve problems, which classical computers can only solve with great effort or not at all – this is the goal currently being pursued by an ever-growing number of research teams worldwide. The reason: Quantum effects, which originate from the world of the smallest particles and structures, enable many new technological applications. So-called superconductors, which allow for processing information and signals according to the laws of quantum mechanics, are considered to be promising components for realizing quantum computers. A sticking point of superconducting nanostructures, however, is that they only function at very low temperatures and are therefore difficult to bring into practical applications.

    Researchers at the University of Münster and Forschungszentrum Jülich now, for the first time, demonstrated what is known as energy quantization in nanowires made of high-temperature superconductors – i. e. superconductors, in which the temperature is elevated below which quantum mechanical effects predominate. The superconducting nanowire then assumes only selected energy states that could be used to encode information. In the high-temperature superconductors, the researchers were also able to observe for the first time the absorption of a single photon, a light particle that serves to transmit information.

    “On the one hand, our results can contribute to the use of considerably simplified cooling technology in quantum technologies in the future, and on the other hand, they offer us completely new insights into the processes governing superconducting states and their dynamics, which are still not understood,” emphasizes study leader Jun. Prof. Carsten Schuck from the Institute of Physics at Münster University. The results may therefore be relevant for the development of new types of computer technology. The study has been published in the journal Nature Communications.

    Background and methods:

    2
    High temperature superconducting microbridge (pink) in gold contacts (yellow)
    © M. Lyatti et al./ Nature Communications

    The scientists used superconductors made of the elements yttrium, barium, copper oxide and oxygen, or YBCO for short, from which they fabricated a few nanometer thin wires. When these structures conduct electrical current physical dynamics called phase slips occur. In the case of YBCO nanowires fluctuations of the charge carrier density cause variations in the supercurrent. The researchers investigated the processes in the nanowires at temperatures below 20 Kelvin, which corresponds to minus 253 degrees Celsius. In combination with model calculations, they demonstrated a quantization of energy states in the nanowires. The temperature at which the wires entered the quantum state was found at 12 to 13 Kelvin – a temperature several hundred times higher than the temperature required for the materials normally used. This enabled the scientists to produce resonators, i.e. oscillating systems tuned to specific frequencies, with much longer lifetimes and to maintain the quantum mechanical states for longer. This is a prerequisite for the long-term development of ever larger quantum computers.

    Absorption of a single photon in high-temperature superconductors

    Further important components for the development of quantum technologies, but potentially also for medical diagnostics, are detectors that can register even single-photons. Carsten Schuck’s research group at Münster University has been working for several years on developing such single-photon detectors based on superconductors. What already works well at low temperatures, scientists all over the world have been trying to achieve with high-temperature superconductors for more than a decade. In the YBCO nanowires used for the study, this attempt has now succeeded for the first time. “Our new findings pave the way for new experimentally verifiable theoretical descriptions and technological developments,” says co-author Martin Wolff from the Schuck research group.

    Participating institutions and funding:

    The superconducting films produced at Forschungszentrum Jülich were nanostructured in Jülich and at the University of Münster, where also the experimental characterization was carried out. The study received financial support from the Ministry of Economics, Innovation, Digitization and Energy of the State of North Rhine-Westphalia and the Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons (ER-C) of the Forschungszentrum Jülich.

    See the full article here .

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    Sitz der WWU
    Foto: MünsterView/Tronquet

    The University of Münster (German: Westfälische Wilhelms-Universität Münster, WWU) is a public university located in the city of Münster, North Rhine-Westphalia in Germany.

    With more than 43,000 students and over 120 fields of study in 15 departments, it is Germany’s fifth largest university and one of the foremost centers of German intellectual life. The university offers a wide range of subjects across the sciences, social sciences and the humanities. Several courses are also taught in English, including PhD programmes as well as postgraduate courses in geoinformatics, geospational technologies or information systems.

    Professors and former students have won ten Leibniz Prizes, the most prestigious as well as the best-funded prize in Europe, and one Fields Medal. The WWU has also been successful in the German government’s Excellence Initiative.

     
  • richardmitnick 12:14 am on February 8, 2020 Permalink | Reply
    Tags: "A Quantum of Solid", , , Cooling a levitated nanoparticle to its motional quantum groundstate., , Nanotechnology, New macroscopic quantum states involving large masses should become possible., Physicists do something very cool, , , Universität Wien   

    From Universität Wien: “A Quantum of Solid” 

    From Universität Wien

    30. January 2020
    Scientific contact
    Univ.-Prof. Dr. Markus Aspelmeyer
    Quantenoptik, Quantennanophysik und Quanteninformation
    Universität Wien
    1090 – Wien, Boltzmanngasse 5
    +43-1-4277-725 31
    markus.aspelmeyer@univie.ac.at

    Dr. Uros Delic, BSc MSc
    Fakultät für Physik
    Universität Wien
    1090 – Wien, Boltzmanngasse 5
    +43-1-4277-72532
    uros.delic@univie.ac.at

    Further inquiry note
    Mag. Alexandra Frey
    Pressebüro und stv. Pressesprecherin
    Universität Wien
    1010 – Wien, Universitätsring 1
    +43-1-4277-175 33
    +43-664-60277-175 33
    alexandra.frey@univie.ac.at

    1
    Scientists from Vienna, Kahan Dare (left) and Manuel Reisenbauer (right) working on the experiment that cooled a levitated nanoparticle to its motional quantum groundstate. (© Lorenzo Magrini, Yuriy Coroli/Universität Wien)

    2
    Scientist from Vienna working on the experiment that cooled a levitated nanoparticle to its motional quantum groundstate. (© Lorenzo Magrini, Yuriy Coroli/Universität Wien)

    3
    Researchers cooled a levitated nanoparticle to the quantum groundstate for the first time. This work was made possible by the recent breakthrough application of coherent scattering in the field of cavity optomechanics. (© Lorenzo Magrini, Yuriy Coroli/Universität Wien)

    Researchers in Austria use lasers to levitate and cool a glass nanoparticle into the quantum regime. Although it is trapped in a room temperature environment, the particle’s motion is solely governed by the laws of quantum physics. The team of scientists from the Universität Wien, the Austrian Academy of Sciences and the Massachusetts Institute of Technology (MIT) published their new study in the journal Science.

    It is well known that quantum properties of individual atoms can be controlled and manipulated by laser light. Even large clouds of hundreds of millions of atoms can be pushed into the quantum regime, giving rise to macroscopic quantum states of matter such as quantum gases or Bose-Einstein condensates, which nowadays are also widely used in quantum technologies. An exciting next step is to extend this level of quantum control to solid state objects. In contrast to atomic clouds, the density of a solid is a billion times higher and all atoms are bound to move together along the object’s center of mass. In that way, new macroscopic quantum states involving large masses should become possible.

    However, entering this new regime is not at all a straightforward endeavour. A first step for achieving such quantum control is to isolate the object under investigation from influences of the environment and to remove all thermal energy – by cooling it down to temperatures very close to absolute zero (-273.15 °C) such that quantum mechanics dominates the particle’s motion. To show this the researchers chose to experiment with a glass bead approximately a thousand times smaller than a typical grain of sand and containing a few hundred million atoms. Isolation from the environment is achieved by optically trapping the particle in a tightly focused laser beam in high vacuum, a trick that was originally introduced by Nobel laureate Arthur Ashkin many decades ago and that is also used for isolating atoms. “The real challenge is for us to cool the particle motion into its quantum ground state. Laser cooling via atomic transitions is well established and a natural choice for atoms, but it does not work for solids”, says lead-author Uros Delic from the Universität Wien.

    For this reason, the team has been working on implementing a laser-cooling method that was proposed by Austrian physicist Helmut Ritsch at the University of Innsbruck and, independently, by study co-author Vladan Vuletic and Nobel laureate Steven Chu. They had recently announced a first demonstration of the working principle, “cavity cooling by coherent scattering”, however they were still limited to operating far away from the quantum regime. “We have upgraded our experiment and are now able not only to remove more background gas but also to send in more photons for cooling”, says Delic. In that way, the motion of the glass bead can be cooled straight into the quantum regime. “It is funny to think about this: the surface of our glass bead is extremely hot, around 300°C, because the laser heats up the electrons in the material. But the motion of the center of mass of the particle is ultra-cold, around 0.00001°C away from absolute zero, and we can show that the hot particle moves in a quantum way.”

    The researchers are excited about the prospects of their work. The quantum motion of solids has also been investigated by other groups all around the world, along with the Vienna team. Thus far, experimental systems were comprised of nano- and micromechanical resonators, in essence drums or diving boards that are clamped to a rigid support structure. “Optical levitation brings in much more freedom: by changing the optical trap – or even switching it off – we can manipulate the nanoparticle motion in completely new ways”, says Nikolai Kiesel, co-author and Assistant Professor at the Universität Wien. Several schemes along these lines have been proposed, amongst others by Austrian-based physicists Oriol Romero-Isart and Peter Zoller at Innsbruck, and may now become possible. For example, in combination with the newly achieved motional ground state the authors expect that this opens new opportunities for unprecedented sensing performance, the study of fundamental processes of heat engines in the quantum regime, as well as the study of quantum phenomena involving large masses. “A decade ago we started this experiment motivated by the prospect of a new category of quantum experiments. We finally have opened the door to this regime.”

    See the full article here .

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    Please help promote STEM in your local schools.

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    Universität Wien Campus

    Universität Wien is a public university located in Vienna, Austria. It was founded by Duke Rudolph IV in 1365 and is the oldest university in the German-speaking world. With its long and rich history, the University of Vienna has developed into one of the largest universities in Europe, and also one of the most renowned, especially in the Humanities. It is associated with 20 Nobel prize winners and has been the academic home to many scholars of historical as well as of academic importance.

     
  • richardmitnick 4:53 pm on February 7, 2020 Permalink | Reply
    Tags: , Magnetic microrobots use capillary forces to coax particles into position, Nanotechnology,   

    From Penn Today: “Magnetic microrobots use capillary forces to coax particles into position” 


    From Penn Today

    February 6, 2020
    Penn Today Staff

    At microscopic scales, picking, placing, collecting, and arranging objects is a persistent challenge. Advances in nanotechnology mean that there are ever more complex things we’d like to build at those sizes, but tools for moving their component parts are lacking.

    1
    Particles are strongly attracted to the corners of square-shaped robots. The green outline shows the trajectory the particle takes as the robot approaches.

    New research from the School of Engineering and Applied Science shows how simple, microscopic robots, remotely driven by magnetic fields, can use capillary forces to manipulate objects floating at an oil-water interface. This system was demonstrated in a study published in the journal Applied Physics Letters.

    The study was led by Kathleen Stebe, Richer & Elizabeth Goodwin Professor in Penn Engineering’s Department of Chemical and Biomolecular Engineering, and Tianyi Yao, a graduate student in her lab. Nicholas Chisholm, a postdoctoral researcher in Stebe’s lab, and Edward Steager, a research scientist in Penn Engineering’s GRASP lab contributed to the research.

    The microrobots in the Penn team’s study are thin slices of magnet, about a third of a millimeter in diameter. Despite having no moving parts or sensors of their own, the researchers refer to them as robots because of their ability to pick and place arbitrary objects that are even smaller than they are.

    That ability is a function of the specialized environment where these microrobots work: at the interface between two liquids. In this study, the interface is between water and hexadecane, a common oil. Once there, the robots deform the shape of that interface, essentially surrounding themselves with an invisible “force field” of capillary interactions.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 11:15 am on February 6, 2020 Permalink | Reply
    Tags: , , , Nanotechnology   

    From MIT News: “Engineers mix and match materials to make new stretchy electronics” 

    MIT News

    From MIT News

    February 5, 2020
    Jennifer Chu

    1
    With a new technique, MIT researchers can peel and stack thin films of metal oxides — chemical compounds that can be designed to have unique magnetic and electronic properties. The films can be mixed and matched to create multi-functional, flexible electronic devices, such as solar-powered skins and electronic fabrics. Image: Felice Frankel

    2
    MIT researchers, from left to right: Kuan Qiao, Jeehwan Kim, Hyun S. Kum, Wei Kong, Sang-Hoon Bae, Jaewoo Shim, Sangho Lee, Chanyeol Choi. Image: Kuan Qiao

    Next-generation devices made with new “peel and stack” method may include electronic chips worn on the skin.

    At the heart of any electronic device is a cold, hard computer chip, covered in a miniature city of transistors and other semiconducting elements. Because computer chips are rigid, the electronic devices that they power, such as our smartphones, laptops, watches, and televisions, are similarly inflexible.

    Now a process developed by MIT engineers may be the key to manufacturing flexible electronics with multiple functionalities in a cost-effective way.

    The process is called “remote epitaxy” and involves growing thin films of semiconducting material on a large, thick wafer of the same material, which is covered in an intermediate layer of graphene. Once the researchers grow a semiconducting film, they can peel it away from the graphene-covered wafer and then reuse the wafer, which itself can be expensive depending on the type of material it’s made from. In this way, the team can copy and peel away any number of thin, flexible semiconducting films, using the same underlying wafer.

    In a paper published today in the journal Nature, the researchers demonstrate that they can use remote epitaxy to produce freestanding films of any functional material. More importantly, they can stack films made from these different materials, to produce flexible, multifunctional electronic devices.

    The researchers expect that the process could be used to produce stretchy electronic films for a wide variety of uses, including virtual reality-enabled contact lenses, solar-powered skins that mold to the contours of your car, electronic fabrics that respond to the weather, and other flexible electronics that seemed until now to be the stuff of Marvel movies.

    “You can use this technique to mix and match any semiconducting material to have new device functionality, in one flexible chip,” says Jeehwan Kim, an associate professor of mechanical engineering at MIT. “You can make electronics in any shape.”

    Kim’s co-authors include Hyun S. Kum, Sungkyu Kim, Wei Kong, Kuan Qiao, Peng Chen, Jaewoo Shim, Sang-Hoon Bae, Chanyeol Choi, Luigi Ranno, Seungju Seo, Sangho Lee, Jackson Bauer, and Caroline Ross from MIT, along with collaborators from the University of Wisconsin at Madison, Cornell University, the University of Virginia, Penn State University, Sun Yat-Sen University, and the Korea Atomic Energy Research Institute.

    Buying time

    Kim and his colleagues reported their first results using remote epitaxy in 2017. Then, they were able to produce thin, flexible films of semiconducting material by first placing a layer of graphene on a thick, expensive wafer made from a combination of exotic metals. They flowed atoms of each metal over the graphene-covered wafer and found the atoms formed a film on top of the graphene, in the same crystal pattern as the underlying wafer. The graphene provided a nonstick surface from which the researchers could peel away the new film, leaving the graphene-covered wafer, which they could reuse.

    In 2018, the team showed that they could use remote epitaxy to make semiconducting materials from metals in groups 3 and 5 of the periodic table, but not from group 4. The reason, they found, boiled down to polarity, or the respective charges between the atoms flowing over graphene and the atoms in the underlying wafer.

    Since this realization, Kim and his colleagues have tried a number of increasingly exotic semiconducting combinations. As reported in this new paper, the team used remote epitaxy to make flexible semiconducting films from complex oxides — chemical compounds made from oxygen and at least two other elements. Complex oxides are known to have a wide range of electrical and magnetic properties, and some combinations can generate a current when physically stretched or exposed to a magnetic field.

    Kim says the ability to manufacture flexible films of complex oxides could open the door to new energy-havesting devices, such as sheets or coverings that stretch in response to vibrations and produce electricity as a result. Until now, complex oxide materials have only been manufactured on rigid, millimeter-thick wafers, with limited flexibility and therefore limited energy-generating potential.

    The researchers did have to tweak their process to make complex oxide films. They initially found that when they tried to make a complex oxide such as strontium titanate (a compound of strontium, titanium, and three oxygen atoms), the oxygen atoms that they flowed over the graphene tended to bind with the graphene’s carbon atoms, etching away bits of graphene instead of following the underlying wafer’s pattern and binding with strontium and titanium. As a surprisingly simple fix, the researchers added a second layer of graphene.

    “We saw that by the time the first layer of graphene is etched off, oxide compounds have already formed, so elemental oxygen, once it forms these desired compounds, does not interact as heavily with graphene,” Kim explains. “So two layers of graphene buys some time for this compound to form.”

    Peel and stack

    The team used their newly tweaked process to make films from multiple complex oxide materials, peeling off each 100-nanometer-thin layer as it was made. They were also able to stack together layers of different complex oxide materials and effectively glue them together by heating them slightly, producing a flexible, multifunctional device.

    “This is the first demonstration of stacking multiple nanometers-thin membranes like LEGO blocks, which has been impossible because all functional electronic materials exist in a thick wafer form,” Kim says.

    In one experiment, the team stacked together films of two different complex oxides: cobalt ferrite, known to expand in the presence of a magnetic field, and PMN-PT, a material that generates voltage when stretched. When the researchers exposed the multilayer film to a magnetic field, the two layers worked together to both expand and produce a small electric current.

    The results demonstrate that remote epitaxy can be used to make flexible electronics from a combination of materials with different functionalities, which previously were difficult to combine into one device. In the case of cobalt ferrite and PMN-PT, each material has a different crystalline pattern. Kim says that traditional epitaxy techniques, which grow materials at high temperatures on one wafer, can only combine materials if their crystalline patterns match. He says that with remote epitaxy, researchers can make any number of different films, using different, reusable wafers, and then stack them together, regardless of their crystalline pattern.

    “The big picture of this work is, you can combine totally different materials in one place together,” Kim says. “Now you can imagine a thin, flexible device made from layers that include a sensor, computing system, a battery, a solar cell, so you could have a flexible, self-powering, internet-of-things stacked chip.”

    The team is exploring various combinations of semiconducting films and is working on developing prototype devices, such as something Kim is calling an “electronic tattoo” — a flexible, transparent chip that can attach and conform to a person’s body to sense and wirelessly relay vital signs such as temperature and pulse.

    “We can now make thin, flexible, wearable electronics with the highest functionality,” Kim says. “Just peel off and stack up.”

    This research was supported, in part, by the U.S. Defense Advanced Research Projects Agency.

    See the full article here .


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    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

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  • richardmitnick 10:34 am on January 24, 2020 Permalink | Reply
    Tags: A nano-enabled platform developed at the center to create and deliver tiny aerosolized water nonodroplets containing non-toxic nature-inspired disinfectants wherever desired., , , , Diarrheal diseases are big killers of kids too., Harvard Chan Center for Nanotechnology and Nanotoxicology looks to improve on soap and water., , Infectious diseases are still emerging., , Microorganisms are smarter than we thought and evolving new strains., Nanotechnology   

    From Harvard Gazette: “Disinfecting your hands with ‘magic’” 

    Harvard University


    From Harvard Gazette

    January 23, 2020
    Alvin Powell
    Photos by Kris Snibbe/Harvard Staff Photographer

    1
    Nanostructures can provide an alternative for hand hygiene that is airless and waterless. “… this is like magic. You don’t see; you don’t feel; you don’t smell; but your hands are sanitized,” says Associate Professor of Aerosol Physics Philip Demokritou.

    Harvard Chan Center for Nanotechnology and Nanotoxicology looks to improve on soap and water.

    Nanosafety researchers at the Harvard T.H. Chan School of Public Health have developed a new intervention to fight infectious disease by more effectively disinfecting the air around us, our food, our hands, and whatever else harbors the microbes that make us sick. The researchers, from the School’s Center for Nanotechnology and Nanotoxicology, were led by Associate Professor of Aerosol Physics Philip Demokritou, the center’s director, and first author Runze Huang, a postdoctoral fellow there. They used a nano-enabled platform developed at the center to create and deliver tiny, aerosolized water nonodroplets containing non-toxic, nature-inspired disinfectants wherever desired. Demokritou talked to the Gazette about the invention and its application on hand hygiene, which was described recently in the journal ACS Sustainable Chemistry and Engineering.

    Q&A
    Philip Demokritou

    GAZETTE: Give us a quick overview of the problem you’re trying to solve.

    DEMOKRITOU: If you go back to the ’60s and the invention of many antibiotics, we thought that the chapter on infectious diseases would be closed. Of course, 60 years later, we now know that’s not true. Infectious diseases are still emerging. Microorganisms are smarter than we thought and evolving new strains. It’s a constant battle. And when I talk about infectious diseases, I’m mainly talking about airborne and foodborne diseases: For example, flu and tuberculosis are airborne diseases, respiratory diseases, which cause millions of deaths a year. Foodborne diseases also kill 500,000 people annually and cost our economy billions of dollars.

    GAZETTE: Diarrheal diseases are big killers of kids, too.

    DEMOKRITOU: It’s a big problem, especially in developing countries with fragmented health care systems.

    GAZETTE: What’s wrong with how we sanitize our hands?

    DEMOKRITOU: We hear all the time that you have to wash your hands. It’s a primary measure to reduce infectious diseases. More recently, we’re also using antiseptics. Alcohol is OK, but we are also using other chemicals like triclosan and chlorhexadine. There’s research linking these chemicals to the increase in antimicrobial resistance, among other drawbacks. In addition, some people are sensitive to frequent washes and rubbing with chemicals. That’s where new approaches come into play. So, within the last four or five years, we’ve been trying to develop nanotechnology-based interventions to fight infectious diseases.

    3
    Harvard Chan School’s Associate Professor Philip Demokritou (right) with research associate Nachiket Vaze (center) and postdoc fellow Runze Huang.

    GAZETTE: So the technology involved here — the engineered water nanostructures — is a couple of years old. What’s new is the application?

    DEMOKRITOU: We have the tools to make these engineered nanomaterials and, in this particular case, we can take water and turn it into an engineered water nanoparticle, which carries its deadly payload, primarily nontoxic, nature-inspired antimicrobials, and kills microorganisms on surfaces and in the air.

    It is fairly simple, you need 12 volts DC, and we combine that with electrospray and ionization to turn water into a nanoaerosol, in which these engineered nanostructures are suspended in the air. These water nanoparticles have unique properties because of their small size and also contain reactive oxygen species. These are hydroxyl radicals, peroxides, and are similar to what nature uses in cells to kill pathogens. These nanoparticles, by design, also carry an electric charge, which increases surface energy and reduces evaporation. That means these engineered nanostructures can remain suspended in air for hours. When the charge dissipates, they become water vapor and disappear.

    Very recently, we started using these structures as a carrier, and we can now incorporate nature-inspired antimicrobials into their chemical structure. These are not super toxic to humans. For instance, my grandmother in Greece used to disinfect her surfaces with lemon juice — citric acid. Or, in milk — and also found in tears — is another highly potent antimicrobial called lysozyme. Nisin is another nature-inspired antimicrobial that bacteria release when they’re competing with other bacteria. Nature provides us with a ton of nontoxic antimicrobials that, if we can find a way to deliver them in a targeted, precise manner, can do the job. No need to invent new and potentially toxic chemicals. Let’s go to nature’s pharmacy and shop.

    When we put these nature-inspired antimicrobials into the engineered water nanostructures, their antimicrobial potency increases dramatically. But we do that without using huge quantities of antimicrobials, about 1 percent or 2 percent by volume. Most of the engineered water nanostructure is still water.

    At this point, these engineered structures are carrying antimicrobials and are charged, and we can use the charge to direct them to surfaces by applying a weak electric field. You can also release them into the air — they’re highly mobile — and they can move around and inactivate flu virus, for example.

    GAZETTE: How would this work with food?

    DEMOKRITOU: This nano-enabled platform can be used as an intervention technology for food safety applications as well. When it comes to disinfecting our food, we’re still using archaic approaches developed in the ’50s. For instance, today we put our fresh produce into chlorine-based solutions, which leave residues that can compromise health. It leaves behind byproducts, which are toxic, and you have to find a way to deal with them as well.

    Instead, you can use the water nanoaerosols that contain nanogram levels of an active ingredient — nature-inspired and not toxic — and disinfect our food. Currently, this novel invention is being explored for use — from the farm to the fork — to enhance food safety and quality.

    3
    Source: “Inactivation of Hand Hygiene-Related Pathogens Using Engineered Water Nanostructures,” Runze Huang, Nachiket Vaze, Anand Soorneedi, Matthew D. Moore, Yalong Xue, Dhimiter Bello, Philip Demokritou

    GAZETTE: So when you use it on food, you would essentially spray the nanoparticles onto a head of lettuce, for example?

    DEMOKRITOU: It depends on the application. You can put this technology in your refrigerator, and it will kill microbes on food surfaces and in the air there and improve food safety. It will also increase shelf life, which is linked to spoilage microorganisms. You can also use this technology for air disinfection. The only thing you need is 12-volt DC, which you can power from your computer USB port. Imagine sitting on a train and you generate an invisible shield of these engineered water nanostructures that protects you and minimizes the risk of getting the flu.

    GAZETTE: If you’re on the train with a bunch of sick people?

    DEMOKRITOU: Exactly, or on an airplane, anywhere you have microorganisms. Most planes recirculate the air, and all it takes is one sick guy — he doesn’t have to be sitting next to you — to get sick. Unfortunately, that’s a big problem. The newer airplanes have filtration to remove some of these pathogens. But this is a very versatile technology that you can pretty much take with you.

    GAZETTE: Let’s talk about hand hygiene.

    DEMOKRITOU: We know hand hygiene is very important, but in addition to the drawbacks of washing with water or using chemicals, the air dryers commonly used in the bathroom environment can aerosolize microbes and put them back in the air and even back on your hands. So there is room to utilize these engineered water nanostructures and develop an alternative that is airless and waterless — because it uses picogram levels of water, your hands will never get wet.

    GAZETTE: So you’re washing your hands, using water. But they don’t get wet?

    DEMOKRITOU: Exactly. And it disinfects hands in a matter of 15–20 seconds, as indicated in our recently published study.

    GAZETTE: As far as an application goes, do you see something similar to the hand driers we all use at highway rest stops? Only, when you stick your hands in, it doesn’t blow? Do you feel anything at all?

    DEMOKRITOU: You don’t feel anything. That’s the problem; this is like magic. You don’t see; you don’t feel; you don’t smell; but your hands are sanitized.

    GAZETTE: So how do people know anything’s happened? As humans we want some sort of stimulation.

    DEMOKRITOU: We could put a light and music to entertain people, but nobody can see a 25-nanometer particle. We are excited to see that there is interest from industry to pursue commercialization of this technology for hand hygiene. We may soon have an airless, waterless apparatus that can be used across the board, though not necessarily in the bathroom environment. This can be a battery-operated device, it can be placed around airports and other spots where people don’t have time or access to water to wash their hands.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Harvard University campus
    Harvard University is the oldest institution of higher education in the United States, established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. It was named after the College’s first benefactor, the young minister John Harvard of Charlestown, who upon his death in 1638 left his library and half his estate to the institution. A statue of John Harvard stands today in front of University Hall in Harvard Yard, and is perhaps the University’s best known landmark.

    Harvard University has 12 degree-granting Schools in addition to the Radcliffe Institute for Advanced Study. The University has grown from nine students with a single master to an enrollment of more than 20,000 degree candidates including undergraduate, graduate, and professional students. There are more than 360,000 living alumni in the U.S. and over 190 other countries.

     
  • richardmitnick 5:54 pm on January 23, 2020 Permalink | Reply
    Tags: "A megalibrary of nanoparticles", , , Nanotechnology, , , Schaak Laboratory   

    From Pennsylvania State University: “A megalibrary of nanoparticles” 

    Penn State Bloc

    From Pennsylvania State University

    January 23, 2020
    Sam Sholtis

    1
    A simple, modular chemical approach could produce over 65,000 different types of complex nanorods. Electron microscope images are shown for 32 of these nanorods, which form with various combinations of materials. Each color represents a different material. Image: Schaak Laboratory, Penn State

    Using straightforward chemistry and a mix-and-match, modular strategy, researchers have developed a simple approach that could produce over 65,000 different types of complex nanoparticles, each containing up to six different materials and eight segments, with interfaces that could be exploited in electrical or optical applications. These rod-shaped nanoparticles are about 55 nanometers long and 20 nanometers wide — by comparison a human hair is about 100,000 nanometers thick — and many are considered to be among the most complex ever made.

    A paper describing the research, by a team of Penn State chemists, appears Jan. 24 in the journal Science.

    “There is a lot of interest in the world of nanoscience in making nanoparticles that combine several different materials — semiconductors, catalysts, magnets, electronic materials,” said Raymond E. Schaak, DuPont Professor of Materials Chemistry at Penn State and the leader of the research team. “You can think about having different semiconductors linked together to control how electrons move through a material, or arranging materials in different ways to modify their optical, catalytic, or magnetic properties. We can use computers and chemical knowledge to predict a lot of this, but the bottleneck has been in actually making the particles, especially at a large-enough scale so that you can actually use them.”

    The team starts with simple nanorods composed of copper and sulfur. They then sequentially replace some of the copper with other metals using a process called “cation exchange.” By altering the reaction conditions, they can control where in the nanorod the copper is replaced — at one end of the rod, at both ends simultaneously, or in the middle. They can then repeat the process with other metals, which can also be placed at precise locations within the nanorods. By performing up to seven sequential reactions with several different metals, they can create a veritable rainbow of particles — over 65,000 different combinations of metal sulfide materials are possible.

    “The real beauty of our method is its simplicity,” said Benjamin C. Steimle, a graduate student at Penn State and the first author of the paper. “It used to take months or years to make even one type of nanoparticle that contains several different materials. Two years ago we were really excited that we could make 47 different metal sulfide nanoparticles using an earlier version of this approach. Now that we’ve made some significant new advances and learned more about these systems, we can go way beyond what anyone has been able to do before. We are now able to produce nanoparticles with previously unimaginable complexity simply by controlling temperature and concentration, all using standard laboratory glassware and principles covered in an Introductory Chemistry course.”

    “The other really exciting aspect of this work is that it is rational and scalable,” said Schaak. “Because we understand how everything works, we can identify a highly complex nanoparticle, plan out a way to make it, and then go into the laboratory and actually make it quite easily. And, these particles can be made in quantities that are useful. In principle, we can now make what we want and as much as we want. There are still limitations, of course — we can’t wait until we are able to do this with even more types of materials — but even with what we have now, it changes how we think about what is possible to make.”

    In addition to Schaak and Steimle, the research team at Penn State included Julie L. Fenton. The research was funded by the U.S. National Science Foundation.

    See the full article here .

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    Please help promote STEM in your local schools.

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    About Penn State

    WHAT WE DO BEST

    We teach students that the real measure of success is what you do to improve the lives of others, and they learn to be hard-working leaders with a global perspective. We conduct research to improve lives. We add millions to the economy through projects in our state and beyond. We help communities by sharing our faculty expertise and research.

    Penn State lives close by no matter where you are. Our campuses are located from one side of Pennsylvania to the other. Through Penn State World Campus, students can take courses and work toward degrees online from anywhere on the globe that has Internet service.

    We support students in many ways, including advising and counseling services for school and life; diversity and inclusion services; social media sites; safety services; and emergency assistance.

    Our network of more than a half-million alumni is accessible to students when they want advice and to learn about job networking and mentor opportunities as well as what to expect in the future. Through our alumni, Penn State lives all over the world.

    The best part of Penn State is our people. Our students, faculty, staff, alumni, and friends in communities near our campuses and across the globe are dedicated to education and fostering a diverse and inclusive environment.

     
  • richardmitnick 10:06 am on January 10, 2020 Permalink | Reply
    Tags: , , Julia Ortony, , Nanotechnology, Self-assembling nanostructures,   

    From MIT News: Women in STEM- “Julia Ortony: Concocting nanomaterials for energy and environmental applications” 

    MIT News

    From MIT News

    January 9, 2020
    Leda Zimmerman | MIT Energy Initiative

    1
    Julia Ortony is the Finmeccanica Career Development Assistant Professor of Engineering in the Department of Materials Science and Engineering. Photo: Lillie Paquette/School of Engineering

    2
    Assistant Professor Julia Ortony (right) and graduate student William Lindemann discuss his experiments on self-assembling nanofibers. Work at the Ortony lab focuses on molecular design and synthesis to create new soft nanomaterials for tackling problems related to energy and the environment. Photo: Lillie Paquette/School of Engineering

    The MIT assistant professor is entranced by the beauty she finds pursuing chemistry.

    A molecular engineer, Julia Ortony performs a contemporary version of alchemy.

    “I take powder made up of disorganized, tiny molecules, and after mixing it up with water, the material in the solution zips itself up into threads 5 nanometers thick — about 100 times smaller than the wavelength of visible light,” says Ortony, the Finmeccanica Career Development Assistant Professor of Engineering in the Department of Materials Science and Engineering (DMSE). “Every time we make one of these nanofibers, I am amazed to see it.”

    But for Ortony, the fascination doesn’t simply concern the way these novel structures self-assemble, a product of the interaction between a powder’s molecular geometry and water. She is plumbing the potential of these nanomaterials for use in renewable energy and environmental remediation technologies, including promising new approaches to water purification and the photocatalytic production of fuel.

    Tuning molecular properties

    Ortony’s current research agenda emerged from a decade of work into the behavior of a class of carbon-based molecular materials that can range from liquid to solid.

    During doctoral work at the University of California at Santa Barbara, she used magnetic resonance (MR) spectroscopy to make spatially precise measurements of atomic movement within molecules, and of the interactions between molecules. At Northwestern University, where she was a postdoc, Ortony focused this tool on self-assembling nanomaterials that were biologically based, in research aimed at potential biomedical applications such as cell scaffolding and regenerative medicine.

    “With MR spectroscopy, I investigated how atoms move and jiggle within an assembled nanostructure,” she says. Her research revealed that the surface of the nanofiber acted like a viscous liquid, but as one probed further inward, it behaved like a solid. Through molecular design, it became possible to tune the speed at which molecules that make up a nanofiber move.

    A door had opened for Ortony. “We can now use state-of-matter as a knob to tune nanofiber properties,” she says. “For the first time, we can design self-assembling nanostructures, using slow or fast internal molecular dynamics to determine their key behaviors.”

    Slowing down the dance

    When she arrived at MIT in 2015, Ortony was determined to tame and train molecules for nonbiological applications of self-assembling “soft” materials.

    “Self-assembling molecules tend to be very dynamic, where they dance around each other, jiggling all the time and coming and going from their assembly,” she explains. “But we noticed that when molecules stick strongly to each other, their dynamics get slow, and their behavior is quite tunable.” The challenge, though, was to synthesize nanostructures in nonbiological molecules that could achieve these strong interactions.

    “My hypothesis coming to MIT was that if we could tune the dynamics of small molecules in water and really slow them down, we should be able to make self-assembled nanofibers that behave like a solid and are viable outside of water,” says Ortony.

    Her efforts to understand and control such materials are now starting to pay off.

    “We’ve developed unique, molecular nanostructures that self-assemble, are stable in both water and air, and — since they’re so tiny — have extremely high surface areas,” she says. Since the nanostructure surface is where chemical interactions with other substances take place, Ortony has leapt to exploit this feature of her creations — focusing in particular on their potential in environmental and energy applications.

    Clean water and fuel from sunlight

    One key venture, supported by Ortony’s Professor Amar G. Bose Fellowship, involves water purification. The problem of toxin-laden drinking water affects tens of millions of people in underdeveloped nations. Ortony’s research group is developing nanofibers that can grab deadly metals such as arsenic out of such water. The chemical groups she attaches to nanofibers are strong, stable in air, and in recent tests “remove all arsenic down to low, nearly undetectable levels,” says Ortony.

    She believes an inexpensive textile made from nanofibers would be a welcome alternative to the large, expensive filtration systems currently deployed in places like Bangladesh, where arsenic-tainted water poses dire threats to large populations.

    “Moving forward, we would like to chelate arsenic, lead, or any environmental contaminant from water using a solid textile fabric made from these fibers,” she says.

    In another research thrust, Ortony says, “My dream is to make chemical fuels from solar energy.” Her lab is designing nanostructures with molecules that act as antennas for sunlight. These structures, exposed to and energized by light, interact with a catalyst in water to reduce carbon dioxide to different gases that could be captured for use as fuel.

    In recent studies, the Ortony lab found that it is possible to design these catalytic nanostructure systems to be stable in water under ultraviolet irradiation for long periods of time. “We tuned our nanomaterial so that it did not break down, which is essential for a photocatalytic system,” says Ortony.

    Students dive in

    While Ortony’s technologies are still in the earliest stages, her approach to problems of energy and the environment are already drawing student enthusiasts.

    Dae-Yoon Kim, a postdoc in the Ortony lab, won the 2018 Glenn H. Brown Prize from the International Liquid Crystal Society for his work on synthesized photo-responsive materials and started a tenure track position at the Korea Institute of Science and Technology this fall. Ortony also mentors Ty Christoff-Tempesta, a DMSE doctoral candidate, who was recently awarded a Martin Fellowship for Sustainability. Christoff-Tempesta hopes to design nanoscale fibers that assemble and disassemble in water to create environmentally sustainable materials. And Cynthia Lo ’18 won a best-senior-thesis award for work with Ortony on nanostructures that interact with light and self-assemble in water, work that will soon be published. She is “my superstar MIT Energy Initiative UROP [undergraduate researcher],” says Ortony.

    Ortony hopes to share her sense of wonder about materials science not just with students in her group, but also with those in her classes. “When I was an undergraduate, I was blown away at the sheer ability to make a molecule and confirm its structure,” she says. With her new lab-based course for grad students — 3.65 (Soft Matter Characterization) — Ortony says she can teach about “all the interests that drive my research.”

    While she is passionate about using her discoveries to solve critical problems, she remains entranced by the beauty she finds pursuing chemistry. Fascinated by science starting in childhood, Ortony says she sought out every available class in chemistry, “learning everything from beginning to end, and discovering that I loved organic and physical chemistry, and molecules in general.”

    Today, she says, she finds joy working with her “creative, resourceful, and motivated” students. She celebrates with them “when experiments confirm hypotheses, and it’s a breakthrough and it’s thrilling,” and reassures them “when they come with a problem, and I can let them know it will be thrilling soon.”

    See the full article here .


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    Please help promote STEM in your local schools.


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    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

    MIT Campus

     
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