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  • richardmitnick 10:13 am on January 8, 2019 Permalink | Reply
    Tags: , Chemistry, , Infrared spectroscopy, , , ,   

    From SLAC National Accelerator Lab: “Study shows single atoms can make more efficient catalysts” 

    From SLAC National Accelerator Lab

    January 7, 2019
    Glennda Chui

    1
    Scientists used a combination of four techniques, represented here by four incoming beams, to reveal in unprecedented detail how a single atom of iridium catalyzes a chemical reaction. (Greg Stewart/SLAC National Accelerator Laboratory)

    Detailed observations of iridium atoms at work could help make catalysts that drive chemical reactions smaller, cheaper and more efficient.

    Catalysts are chemical matchmakers: They bring other chemicals close together, increasing the chance that they’ll react with each other and produce something people want, like fuel or fertilizer.

    Since some of the best catalyst materials are also quite expensive, like the platinum in a car’s catalytic converter, scientists have been looking for ways to shrink the amount they have to use.

    Now scientists have their first direct, detailed look at how a single atom catalyzes a chemical reaction. The reaction is the same one that strips poisonous carbon monoxide out of car exhaust, and individual atoms of iridium did the job up to 25 times more efficiently than the iridium nanoparticles containing 50 to 100 atoms that are used today.

    The research team, led by Ayman M. Karim of Virginia Tech, reported the results in Nature Catalysis.

    “These single-atom catalysts are very much a hot topic right now,” said Simon R. Bare, a co-author of the study and distinguished staff scientist at the Department of Energy’s SLAC National Accelerator Laboratory, where key parts of the work took place. “This gives us a new lens to look at reactions through, and new insights into how they work.”

    Karim added, “To our knowledge, this is the first paper to identify the chemical environment that makes a single atom catalytically active, directly determine how active it is compared to a nanoparticle, and show that there are very fundamental differences – entirely different mechanisms – in the way they react.”

    Is smaller really better?

    Catalysts are the backbone of the chemical industry and essential to oil refining, where they help break crude oil into gasoline and other products. Today’s catalysts often come in the form of nanoparticles attached to a surface that’s porous like a sponge – so full of tiny holes that a single gram of it, unfolded, might cover a basketball court. This creates an enormous area where millions of reactions can take place at once. When gas or liquid flows over and through the spongy surface, chemicals attach to the nanoparticles, react with each other and float away. Each catalyst is designed to promote one specific reaction over and over again.

    But catalytic reactions take place only on the surfaces of nanoparticles, Bare said, “and even though they are very small particles, the expensive metal on the inside of the nanoparticle is wasted.”

    Individual atoms, on the other hand, could offer the ultimate in efficiency. Each and every atom could act as a catalyst, grabbing chemical reactants and holding them close together until they bond. You could fit a lot more of them in a given space, and not a speck of precious metal would go to waste.

    Single atoms have another advantage: Unlike clusters of atoms, which are bound to each other, single atoms are attached only to the surface, so they have more potential binding sites available to perform chemical tricks – which in this case came in very handy.

    Research on single-atom catalysts has exploded over the past few years, Karim said, but until now no one has been able to study how they function in enough detail to see all the fleeting intermediate steps along the way.

    Grabbing some help

    To get more information, the team looked at a simple reaction where single atoms of iridium split oxygen molecules in two, and the oxygen atoms then react with carbon monoxide to create carbon dioxide.

    They used four approaches­ – infrared spectroscopy, electron microscopy, theoretical calculations and X-ray spectroscopy with beams from SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) – to attack the problem from different angles, and this was crucial for getting a complete picture.

    SLAC/SSRL

    SLAC SSRL Campus

    “It’s never just one thing that gives you the full answer,” Bare said. “It’s always multiple pieces of the jigsaw puzzle coming together.”

    The team discovered that each iridium atom does, in fact, perform a chemical trick that enhances its performance. It grabs a single carbon monoxide molecule out of the passing flow of gas and holds onto it, like a person tucking a package under their arm. The formation of this bond triggers tiny shifts in the configuration of the iridium atom’s electrons that help it split oxygen, so it can react with the remaining carbon monoxide gas and convert it to carbon dioxide much more efficiently.

    More questions lie ahead: Will this same mechanism work in other catalytic reactions, allowing them to run more efficiently or at lower temperatures? How do the nature of the single-atom catalyst and the surface it sits on affect its binding with carbon monoxide and the way the reaction proceeds?

    The team plans to return to SSRL in January to continue the work.

    See the full article here .


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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

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  • richardmitnick 10:55 am on January 7, 2019 Permalink | Reply
    Tags: , , Chemistry, NSF funds innovative stable isotope equipment at UC Santa Cruz, , Stable Isotope Laboratory,   

    From UC Santa Cruz: “NSF funds innovative stable isotope equipment at UC Santa Cruz” 

    UC Santa Cruz

    From UC Santa Cruz

    January 02, 2019
    Tom Garlinghouse
    publicaffairs@ucsc.edu

    1
    Ocean Sciences Professor Matthew McCarthy (left) with lab manager Dyke Andreason in the UC Santa Cruz Stable Isotope Laboratory. (Photos by Carolyn Lagattuta)

    2
    With the new grant, the Stable Isotope Lab will acquire a cutting-edge instrument called an isotope-ratio-monitoring mass spectrometer (IRMS).

    A major grant from the National Science Foundation (NSF) will help fund the acquisition of a new state-of-the-art spectrometer for the Stable Isotope Laboratory at UC Santa Cruz.

    The $805,000 project for the new instrument was primarily supported by a $564,184 NSF grant, one of three awards the campus received this year from NSF’s highly competitive Major Research Instrumentation program. In addition, the Office of Research, the Division of Physical and Biological Sciences, the Division of Social Sciences, three departments and a research institute all contributed a total of $241,000 to fully fund the instrument expansion.

    Principal investigator Matthew McCarthy, a professor of ocean sciences, said the new equipment will support research across a wide range of disciplines, ranging from oceanography and earth science, paleontology, anthropology, ecology and fundamental biochemical cycle research.

    “We want our facility to be a place that diverse scientists from UC Santa Cruz and across our region can use,” McCarthy said. “My vision for this is to be a national and international center for novel and leading-edge stable isotope approaches.”

    Powerful tool

    Stable isotope analysis is a powerful tool for tracing carbon and nutrients as they cycle through food webs and the environment. UCSC’s Stable Isotope Laboratory, established in 1994, has been one of the world’s top facilities for research on climatic and oceanographic conditions in Earth’s past (paleoclimatology and paleoceanography). Scientists using the lab are at the forefront of research on, for example, ancient greenhouse climates, El Niño Southern Oscillation events, controls on rainfall in California, the vulnerability of species to global change, and other topics. According to McCarthy, research associated with the laboratory has generated over 165 scientific papers since 2004.

    Isotopes are different forms of the same element. The most common naturally occurring isotope of carbon, for example, is carbon–12 (the 12 refers to the number of protons and neutrons in the nucleus of the atom). Other carbon isotopes include carbon–14, which is unstable and emits radiation as it decays over time, and carbon–13, which is a stable isotope. While carbon–14 is useful for carbon dating, stable isotopes of carbon, nitrogen, and other elements are useful in a wide range of scientific analyses.

    Stable isotopes have proven especially valuable in the analysis of diet, where they can be used to distinguish between different sources of food. Isotopes in the food animals or humans eat are stored in their bones, teeth, and other tissues. By measuring the ratios of certain isotopes in tissue samples, researchers can determine, for example, where an animal fed and whether it ate primarily a marine, terrestrial, or freshwater diet. This ability has made stable isotopes an increasingly invaluable tool for not only ecology, but also paleontology, anthropology, and even forensics.

    With the new grant, the Stable Isotope Lab will acquire a cutting-edge instrument called an isotope-ratio-monitoring mass spectrometer (IRMS). McCarthy explained that the IRMS is a powerful tool for performing compound-specific isotope analysis (CSIA).

    CSIA is a way of measuring isotopes in individual molecules rather than bulk samples, which is the traditional method of stable isotope analysis. This application has proven especially useful for measuring isotope ratios of carbon and nitrogen in amino acids. This type of analysis is a relatively new but very promising field of study that “has exploded in the last 15 years,” McCarthy said.

    Innovative research

    The new spectrometer will also substantially modernize the existing isotope lab, which was last updated in 2004 and contains still usable but rapidly aging instruments that are now limited in their capabilities. With this new equipment, UC Santa Cruz will continue to be in the forefront of innovative research in the years to come, McCarthy said.

    “My vision for this project was really to not just expand things, but to make us a premier, cutting-edge place in the world to do compound-specific isotope analysis across different disciplines,” he said.

    CSIA can be used in a broad range of scientific disciplines, including oceanography, biology, ecology, astrobiology, paleontology, Earth science, and environmental studies. One expanding area at UCSC in which CSIA has proven of particular value is in anthropology and archaeology. Traditionally, bulk sample measurement of ratios between carbon–13 and nitrogen–15 in human bone collagen have helped to distinguish diets composed of, for example, animal protein versus plant protein or terrestrial versus marine diets.

    Recently, however, it is becoming increasingly clear that this technique is failing to provide adequate data in regions with complex ecosystems where diverse dietary resources are available. Compound-specific isotope analysis of individual amino acids, by contrast, can distinguish these more complex dietary regimes.

    Vicky Oelze, assistant professor in biological anthropology, sees great potential for CSIA in her research on the diets and ecology of apes and prehistoric humans. “I want to use the compound-specific approach to answer questions on meat consumption in wild chimpanzees, because the patterns we’re seeing with bulk isotopes are often super confusing,” Oelze said. “If this method works out, we have a much more precise tool we can use for future work on meat consumption frequencies in wild fauna.”

    CSIA will also be useful in a number of other areas, such as McCarthy’s research using deep-sea corals to look at millennial-scale oceanographic change. It can be used to investigate biogeochemical cycles, such as how land use changes have impacted nutrient dynamics in coastal and marine habitats, and for other applications such as studying the changes in food web dynamics in modern populations of marine mammals.

    If all goes well, the new isotope equipment will be installed and ready for use in standard applications in spring 2019, McCarthy said.

    The Stable Isotope Lab in the Earth and Marine Sciences building will be expanded to accommodate the new isotope-ratio-monitoring mass spectrometer. The lab will bring together scientists from different departments, divisions, and regional institutions, and will serve as a training ground for undergraduate and graduate students, as well as visiting researchers.

    See the full article here .


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    UCSC Lick Observatory, Mt Hamilton, in San Jose, California, Altitude 1,283 m (4,209 ft)

    .

    UCO Lick Shane Telescope
    UCO Lick Shane Telescope interior
    Shane Telescope at UCO Lick Observatory, UCSC

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA

    UC Santa Cruz campus
    The University of California, Santa Cruz, opened in 1965 and grew, one college at a time, to its current (2008-09) enrollment of more than 16,000 students. Undergraduates pursue more than 60 majors supervised by divisional deans of humanities, physical & biological sciences, social sciences, and arts. Graduate students work toward graduate certificates, master’s degrees, or doctoral degrees in more than 30 academic fields under the supervision of the divisional and graduate deans. The dean of the Jack Baskin School of Engineering oversees the campus’s undergraduate and graduate engineering programs.

    UCSC is the home base for the Lick Observatory.

    Lick Observatory's Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building
    Lick Observatory’s Great Lick 91-centimeter (36-inch) telescope housed in the South (large) Dome of main building

    Search for extraterrestrial intelligence expands at Lick Observatory
    New instrument scans the sky for pulses of infrared light
    March 23, 2015
    By Hilary Lebow
    1
    The NIROSETI instrument saw first light on the Nickel 1-meter Telescope at Lick Observatory on March 15, 2015. (Photo by Laurie Hatch) UCSC Lick Nickel telescope

    Astronomers are expanding the search for extraterrestrial intelligence into a new realm with detectors tuned to infrared light at UC’s Lick Observatory. A new instrument, called NIROSETI, will soon scour the sky for messages from other worlds.

    “Infrared light would be an excellent means of interstellar communication,” said Shelley Wright, an assistant professor of physics at UC San Diego who led the development of the new instrument while at the University of Toronto’s Dunlap Institute for Astronomy & Astrophysics.

    Wright worked on an earlier SETI project at Lick Observatory as a UC Santa Cruz undergraduate, when she built an optical instrument designed by UC Berkeley researchers. The infrared project takes advantage of new technology not available for that first optical search.

    Infrared light would be a good way for extraterrestrials to get our attention here on Earth, since pulses from a powerful infrared laser could outshine a star, if only for a billionth of a second. Interstellar gas and dust is almost transparent to near infrared, so these signals can be seen from great distances. It also takes less energy to send information using infrared signals than with visible light.

    Frank Drake, professor emeritus of astronomy and astrophysics at UC Santa Cruz and director emeritus of the SETI Institute, said there are several additional advantages to a search in the infrared realm.

    “The signals are so strong that we only need a small telescope to receive them. Smaller telescopes can offer more observational time, and that is good because we need to search many stars for a chance of success,” said Drake.

    The only downside is that extraterrestrials would need to be transmitting their signals in our direction, Drake said, though he sees this as a positive side to that limitation. “If we get a signal from someone who’s aiming for us, it could mean there’s altruism in the universe. I like that idea. If they want to be friendly, that’s who we will find.”

    Scientists have searched the skies for radio signals for more than 50 years and expanded their search into the optical realm more than a decade ago. The idea of searching in the infrared is not a new one, but instruments capable of capturing pulses of infrared light only recently became available.

    “We had to wait,” Wright said. “I spent eight years waiting and watching as new technology emerged.”

    Now that technology has caught up, the search will extend to stars thousands of light years away, rather than just hundreds. NIROSETI, or Near-Infrared Optical Search for Extraterrestrial Intelligence, could also uncover new information about the physical universe.

    “This is the first time Earthlings have looked at the universe at infrared wavelengths with nanosecond time scales,” said Dan Werthimer, UC Berkeley SETI Project Director. “The instrument could discover new astrophysical phenomena, or perhaps answer the question of whether we are alone.”

    NIROSETI will also gather more information than previous optical detectors by recording levels of light over time so that patterns can be analyzed for potential signs of other civilizations.

    “Searching for intelligent life in the universe is both thrilling and somewhat unorthodox,” said Claire Max, director of UC Observatories and professor of astronomy and astrophysics at UC Santa Cruz. “Lick Observatory has already been the site of several previous SETI searches, so this is a very exciting addition to the current research taking place.”

    NIROSETI will be fully operational by early summer and will scan the skies several times a week on the Nickel 1-meter telescope at Lick Observatory, located on Mt. Hamilton east of San Jose.

    The NIROSETI team also includes Geoffrey Marcy and Andrew Siemion from UC Berkeley; Patrick Dorval, a Dunlap undergraduate, and Elliot Meyer, a Dunlap graduate student; and Richard Treffers of Starman Systems. Funding for the project comes from the generous support of Bill and Susan Bloomfield.

     
  • richardmitnick 12:44 pm on January 3, 2019 Permalink | Reply
    Tags: , , Chemistry, Chemists create new quasicrystal material from nanoparticle building blocks,   

    From Brown University: “Chemists create new quasicrystal material from nanoparticle building blocks” 

    Brown University
    From Brown University

    December 20, 2018

    Kevin Stacey
    kevin_stacey@brown.edu
    401-863-3766

    1
    Quasicrystal lattice, Researchers have shown that special nanoparticle building blocks can assemble themselves into a quasicrystalline lattice, an ordered structure with no discernible repeating pattern and exotic symmetries. Chen Lab / Brown University

    2
    Powerful pyramids, Ou Chen, assistant professor of chemistry, holds a mock-up of the tetrahedral quantum dot building blocks used to create macro-scale superstructures.

    Brown University researchers have discovered a new type of quasicrystal, a class of materials whose existence was thought to be impossible until the 1980s.

    The strange class of materials known as quasicrystals has a new member. In a paper published on Thursday, Dec. 20, in Science, researchers from Brown University describe a quasicrystalline superlattice that self-assembles from a single type of nanoparticle building blocks.

    This is the first definitive observation of a quasicrystalline superlattice formed from a single component, the researchers say. The discovery provides new insight into how these strange crystal-like structures can emerge.

    “Single-component quasicrystal lattices have been predicted mathematically and in computer simulations, but hadn’t been demonstrated before this,” said Ou Chen, an assistant professor of chemistry at Brown and the paper’s senior author. “It’s a fundamentally new type of quasicrystal, and we’ve been able to figure out the rules for making it, which will be useful in the continued study of quasicrystal structures.”

    Quasicrystal materials were first discovered in the 1980s by the chemist Dan Shechtman, who in 2011 was awarded the Nobel Prize for the discovery. Unlike crystals, which consist of ordered patterns that repeat, quasicrystals are ordered but their patterns don’t repeat. Quasicrystals also have symmetries that aren’t possible in traditional crystals. Normal crystals, for example, can have three-fold symmetries that emerge from repeating triangles or four-fold symmetry from repeating cubes. Two- and six-fold symmetries are also possible. But quasicrystals can have exotic five-, 10- or 12-fold symmetries, all of which are “forbidden” in normal crystals.

    The first quasicrystalline materials discovered were metal alloys, usually aluminum with one or more other metals. So far, these materials have found use as non-stick coatings for frying pans and anti-corrosive coatings for surgical equipment. But there’s been much interest in making new types of quasicrystal materials — including materials made from self-assembling nanoparticles.

    Chen and his colleagues hadn’t originally set out to research quasicrystals. Much of Chen’s work has been about bridging the gap between the nanoscale and macroscale worlds by building superstructures out of nanoparticle building blocks. About two years ago, he designed a new type of nanoparticle building block — a tetrahedral (pyramid-shaped) quantum dot. Whereas most research on building structures from nanoparticles has been done with spherical particles, Chen’s tetrahedra can pack more tightly and potentially form more complex and robust structures.

    Another key feature of Chen’s particles is that they’re anisotropic, meaning they have different properties depending upon their orientation relative to each other. One face of each pyramid particle has a different ligand (a bonding agent) than all other faces. Faces with like ligands tend to bond with each other when the particles assemble themselves into larger structures. That directed bonding makes for more interesting and complex structures compared with particles lacking anisotropy.

    In research published recently in the journal Nature, Chen and his team demonstrated one of the most complex superstructures created to date from nanoparticle building blocks. In that work, the superstructures were assembled while the particles interacted with a solid substrate. For this latest work, Chen and his colleagues wanted to see what kind of structures the particles would make when assembled on top of a liquid surface, which gives the particles more degrees of freedom when assembling themselves.

    The team was shocked to find that the resulting structure was actually a quasicrystalline lattice.

    “When I realized the pattern I was seeing was a quasicrystal, I emailed Ou and said ‘I think I’ve found something super-great,’” said Yasutaka Nagaoka, a postdoctoral scholar in Chen’s lab and the lead author of the new paper. “It was really exciting.”

    Using transmission electron microscopy, the researchers showed the particles assembled into discrete decagons (10-sided polygons), which stitched themselves together to form a quasicrystal lattice with 10-fold rotational symmetry. That 10-fold symmetry, forbidden in regular crystals, was a telltale sign of a quasicrystalline structure.

    The researchers were also able to divine the “rules” by which their structure formed. While decagons are the primary units of the structure, they are not — and cannot be — the only units in the structure. Forming a quasicrystal is a little like tiling a floor. The tiles have to fit together in a way that covers the entire floor without leaving any gaps. That can’t be done using only decagons because there’s no way to fit them together that doesn’t leave gaps. Other shapes are needed to fill the holes.

    The same goes for this new quasicrystal structure — they require secondary “tiles” that can fill the gaps between decagons. The researchers found that what enabled their structure to work is that the decagons have flexible edges. When necessary, one or more of their points could be flattened out. By doing that, they could morph into polygons with nine, eight, seven, six or five sides — whatever was required to fill the space between decagons.

    3
    The researchers showed how the nanoparticle decagons flexed their edges to in order to fit together in a quasicrystalline lattice.

    “These decagons are in this confined space that they have to share peacefully,” Chen said. “So they do it by making their edges flexible when they need to.”

    From that observation, the researchers were able to develop a new rule for forming quasicrystals that they call the “flexible polygon tiling rule.” That rule, Chen says, will be useful in continued study of the relatively new area of quasicrystals.

    “We think this work can inform research in material science, chemistry, mathematics and even art and design,” Chen said.

    Nagaoka’s and Chen’s co-authors on the paper were Hua Zhu and Dennis Eggert.

    See the full article here .

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    Welcome to Brown

    Brown U Robinson Hall
    Located in historic Providence, Rhode Island and founded in 1764, Brown University is the seventh-oldest college in the United States. Brown is an independent, coeducational Ivy League institution comprising undergraduate and graduate programs, plus the Alpert Medical School, School of Public Health, School of Engineering, and the School of Professional Studies.

    With its talented and motivated student body and accomplished faculty, Brown is a leading research university that maintains a particular commitment to exceptional undergraduate instruction.

    Brown’s vibrant, diverse community consists of 6,000 undergraduates, 2,000 graduate students, 400 medical school students, more than 5,000 summer, visiting and online students, and nearly 700 faculty members. Brown students come from all 50 states and more than 100 countries.

    Undergraduates pursue bachelor’s degrees in more than 70 concentrations, ranging from Egyptology to cognitive neuroscience. Anything’s possible at Brown—the university’s commitment to undergraduate freedom means students must take responsibility as architects of their courses of study.

     
  • richardmitnick 12:31 pm on December 18, 2018 Permalink | Reply
    Tags: , , , Chemistry, , , Planetary HAZE (PHAZER) chamber   

    From JHU HUB: “Alien imposters: Planets with oxygen don’t necessarily have life, study finds” 

    Johns Hopkins

    From JHU HUB

    12.17.18
    Chanapa Tantibanchachai

    1
    Chao He shows off the lab’s PHAZER setup. Image credit: Chanapa Tantibanchachai

    In their search for life in solar systems near and far, researchers have often accepted the presence of oxygen in a planet’s atmosphere as the surest sign that life may be present there. A new Johns Hopkins study, however, recommends a reconsideration of that rule of thumb.

    Simulating in the lab the atmospheres of planets beyond the solar system, researchers successfully created both organic compounds and oxygen, absent of life.

    The findings, published Dec. 11 by the journal ACS Earth and Space Chemistry, serve as a cautionary tale for researchers who suggest the presence of oxygen and organics on distant worlds is evidence of life there.

    2
    A CO2-rich planetary atmosphere exposed to a plasma discharge in Sarah Hörst’s lab. Image credit: Chao He

    “Our experiments produced oxygen and organic molecules that could serve as the building blocks of life in the lab, proving that the presence of both doesn’t definitively indicate life,” says Chao He, assistant research scientist in the Johns Hopkins University Department of Earth and Planetary Sciences and the study’s first author. “Researchers need to more carefully consider how these molecules are produced.”

    Oxygen makes up 20 percent of Earth’s atmosphere and is considered one of the most robust biosignature gases in Earth’s atmosphere. In the search for life beyond Earth’s solar system, however, little is known about how different energy sources initiate chemical reactions and how those reactions can create biosignatures like oxygen. While other researchers have run photochemical models on computers to predict what exoplanet atmospheres might be able to create, no such simulations to his knowledge have before now been conducted in the lab.

    The research team performed the simulation experiments in a specially designed Planetary HAZE (PHAZER) chamber in the lab of Sarah Hörst, assistant professor of Earth and planetary sciences and the paper’s co-author. The researchers tested nine different gas mixtures, consistent with predictions for super-Earth and mini-Neptune type exoplanet atmospheres; such exoplanets are the most abundant type of planet in our Milky Way galaxy. Each mixture had a specific composition of gases such as carbon dioxide, water, ammonia, and methane, and each was heated at temperatures ranging from about 80 to 700 degrees Fahrenheit.

    He and the team allowed each gas mixture to flow into the PHAZER setup and then exposed the mixture to one of two types of energy, meant to mimic energy that triggers chemical reactions in planetary atmospheres: plasma from an alternating current glow discharge or light from an ultraviolet lamp. Plasma, an energy source stronger than UV light, can simulate electrical activities like lightning and/or energetic particles, and UV light is the main driver of chemical reactions in planetary atmospheres such as those on Earth, Saturn, and Pluto.

    After running the experiments continuously for three days, corresponding to the amount of time gas would be exposed to energy sources in space, the researchers measured and identified resulting gasses with a mass spectrometer, an instrument that sorts chemical substances by their mass to charge ratio.

    The research team found multiple scenarios that produced both oxygen and organic molecules that could build sugars and amino acids—raw materials for which life could begin—such as formaldehyde and hydrogen cyanide.

    “People used to suggest that oxygen and organics being present together indicates life, but we produced them abiotically in multiple simulations,” He says. “This suggests that even the co-presence of commonly accepted biosignatures could be a false positive for life.”

    See the full article here .


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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 11:30 am on November 16, 2018 Permalink | Reply
    Tags: , , Chemistry, Shedding new light on photosynthesis, , University of Michigan researchers have developed a powerful microscope that can map how light energy migrates in photosynthetic bacteria on timescales of one-quadrillionth of a second.   

    From University of Michigan: “Shedding new light on photosynthesis” 

    U Michigan bloc

    From University of Michigan

    October 11, 2018
    Morgan Sherburne
    morganls@umich.edu

    1
    Employing a series of ultrashort laser pulses, a new microscope reveals intricate details that govern photosynthetic processes in purple bacteria. Image credit: Vivek Tiwari, Yassel Acosta and Jennifer Ogilvie

    University of Michigan researchers have developed a powerful microscope that can map how light energy migrates in photosynthetic bacteria on timescales of one-quadrillionth of a second.

    The microscope could help researchers develop more efficient organic photovoltaic materials, a type of solar cell that could provide cheaper energy than silicon-based solar cells.

    In photosynthetic plants and bacteria, light hits the leaf or bacteria and a system of tiny light-harvesting antenna shuttle it along through proteins to what’s called a reaction center. Here, light is “trapped” and turned into metabolic energy for the organisms.

    Jennifer Ogilvie, U-M professor of physics and biophysics, and her team want to capture the movement of this light energy through proteins in a cell, and the team has taken one step toward that goal in developing this microscope. Their study has been published in Nature Communications.

    Ogilvie, graduate student Yassel Acosta and postdoctoral fellow Vivek Tiwari worked together to develop the microscope, which uses a method called two-dimensional electronic spectroscopy to generate images of energy migration within proteins during photosynthesis. The microscope images an area the size of one-fifth of a human blood cell and can capture events that take a period of one-quadrillionth of a second.

    Two-dimensional spectroscopy works by reading the energy levels within a system in two ways. First, it reads the wavelength of light that’s absorbed in a photosynthetic system. Then, it reads the wavelength of light detected within the system, allowing energy to be tracked as it flows through the organism.

    The instrument combines this method with a microscope to measure a signal from nearly a million times smaller volumes than before. Previous measurements imaged samples averaged over sections that were a million times larger. Averaging over large sections obscures the different ways energy might be moving within the same system.

    “We’ve now combined both of those techniques so we can get at really fast processes as well as really detailed information about how these molecules are interacting,” Ogilvie said. “If I look at one nanoscopic region of my sample versus another, the spectroscopy can look very different. Previously, I didn’t know that, because I only got the average measurement. I couldn’t learn about the differences, which can be important for understanding how the system works.”

    In developing the microscope, Ogilvie and her team studied colonies of photosynthetic purple bacterial cells. Previously, scientists have mainly looked at purified parts of these types of cells. By looking at an intact cell system, Ogilvie and her team were able to observe how a complete system’s different components interacted.

    The team also studied bacteria that had been grown in high light conditions, low light conditions and a mixture of both. By tracking light emitted from the bacteria, the microscope enabled them to view how the energy level structure and flow of energy through the system changed depending on the bacteria’s light conditions.

    Similarly, this microscope can help scientists understand how organic photovoltaic materials work, Ogilvie says. Instead of the light-harvesting antennae complexes found in plants and bacteria, organic photovoltaic materials have what are called “donor” molecules and “acceptor” molecules. When light travels through these materials, the donor molecule sends electrons to acceptor molecules, generating electricity.

    “We might find there are regions where the excitation doesn’t produce a charge that can be harvested, and then we might find regions where it works really well,” Ogilvie said. “If we look at the interactions between these components, we might be able to correlate the material’s morphology with what’s working well and what isn’t.”

    In organisms, these zones occur because one area of the organism might not be receiving as much light as another area, and therefore is packed with light-harvesting antennae and few reaction centers. Other areas might be flooded with light, and bacteria may have fewer antennae—but more reaction centers. In photovoltaic material, the distribution of donor and receptor molecules may change depending on the material’s morphology. This could affect the material’s efficiency in converting light into electricity.

    “All of these materials have to have different components that do different things—components that will absorb the light, components that will take that the energy from the light and convert it to something that can be used, like electricity,” Ogilvie said. “It’s a holy grail to be able to map in space and time the exact flow of energy through these systems.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    stem

    Stem Education Coalition

    U MIchigan Campus

    The University of Michigan (U-M, UM, UMich, or U of M), frequently referred to simply as Michigan, is a public research university located in Ann Arbor, Michigan, United States. Originally, founded in 1817 in Detroit as the Catholepistemiad, or University of Michigania, 20 years before the Michigan Territory officially became a state, the University of Michigan is the state’s oldest university. The university moved to Ann Arbor in 1837 onto 40 acres (16 ha) of what is now known as Central Campus. Since its establishment in Ann Arbor, the university campus has expanded to include more than 584 major buildings with a combined area of more than 34 million gross square feet (781 acres or 3.16 km²), and has two satellite campuses located in Flint and Dearborn. The University was one of the founding members of the Association of American Universities.

    Considered one of the foremost research universities in the United States,[7] the university has very high research activity and its comprehensive graduate program offers doctoral degrees in the humanities, social sciences, and STEM fields (Science, Technology, Engineering and Mathematics) as well as professional degrees in business, medicine, law, pharmacy, nursing, social work and dentistry. Michigan’s body of living alumni (as of 2012) comprises more than 500,000. Besides academic life, Michigan’s athletic teams compete in Division I of the NCAA and are collectively known as the Wolverines. They are members of the Big Ten Conference.

     
  • richardmitnick 5:53 pm on November 12, 2018 Permalink | Reply
    Tags: , , Chemistry, MicroED-micro-electron diffraction, , NMR-nuclear magnetic resonance, , , ,   

    From Caltech: “From Beaker to Solved 3-D Structure in Minutes” 

    Caltech Logo

    From Caltech

    11/12/2018

    Whitney Clavin
    (626) 395-1856
    wclavin@caltech.edu

    1
    Graduate student Tyler Fulton prepares samples of small molecules in a lab at Caltech. Credit: Caltech

    2
    Close-up of a powder containing small molecules like those that gave rise to 3-D structures in the new study. (The copper piece is a sample holder used with microscopes.) Credit: Caltech/Stoltz Lab

    3
    Brian Stoltz and Tyler Fulton. Credit: Caltech

    UCLA/Caltech team uncovers a new and simple way to learn the structures of small molecules.

    In a new study that one scientist called jaw-dropping, a joint UCLA/Caltech team has shown that it is possible to obtain the structures of small molecules, such as certain hormones and medications, in as little as 30 minutes. That’s hours and even days less than was possible before.

    The team used a technique called micro-electron diffraction (MicroED), which had been used in the past to learn the 3-D structures of larger molecules, specifically proteins. In this new study, the researchers show that the technique can be applied to small molecules, and that the process requires much less preparation time than expected. Unlike related techniques—some of which involve growing crystals the size of salt grains—this method, as the new study demonstrates, can work with run-of-the-mill starting samples, sometimes even powders scraped from the side of a beaker.

    “We took the lowest-brow samples you can get and obtained the highest-quality structures in barely any time,” says Caltech professor of chemistry Brian Stoltz, who is a co-author on the new study, published in the journal ACS Central Science. “When I first saw the results, my jaw hit the floor.” Initially released on the pre-print server Chemrxiv in mid-October, the article has been viewed more than 35,000 times.

    The reason the method works so well on small-molecule samples is that while the samples may appear to be simple powders, they actually contain tiny crystals, each roughly a billion times smaller than a speck of dust. Researchers knew about these hidden microcrystals before, but did not realize they could readily reveal the crystals’ molecular structures using MicroED. “I don’t think people realized how common these microcrystals are in the powdery samples,” says Stoltz. “This is like science fiction. I didn’t think this would happen in my lifetime—that you could see structures from powders.”

    4
    This movie [animated in the full article] is an example of electron diffraction (MicroED) data collection, in which electrons are fired at a nanocrystal while being continuously rotated. Data from the movie are ultimately converted to a 3-D chemical structure. Credit: UCLA/Caltech

    The results have implications for chemists wishing to determine the structures of small molecules, which are defined as those weighing less than about 900 daltons. (A dalton is about the weight of a hydrogen atom.) These tiny compounds include certain chemicals found in nature, some biological substances like hormones, and a number of therapeutic drugs. Possible applications of the MicroED structure-finding methodology include drug discovery, crime lab analysis, medical testing, and more. For instance, Stoltz says, the method might be of use in testing for the latest performance-enhancing drugs in athletes, where only trace amounts of a chemical may be present.

    “The slowest step in making new molecules is determining the structure of the product. That may no longer be the case, as this technique promises to revolutionize organic chemistry,” says Robert Grubbs, Caltech’s Victor and Elizabeth Atkins Professor of Chemistry and a winner of the 2005 Nobel Prize in Chemistry, who was not involved in the research. “The last big break in structure determination before this was nuclear magnetic resonance spectroscopy, which was introduced by Jack Roberts at Caltech in the late ’60s.”

    Like other synthetic chemists, Stoltz and his team spend their time trying to figure out how to assemble chemicals in the lab from basic starting materials. Their lab focuses on such natural small molecules as the fungus-derived beta-lactam family of compounds, which are related to penicillins. To build these chemicals, they need to determine the structures of the molecules in their reactions—both the intermediate molecules and the final products—to see if they are on the right track.

    One technique for doing so is X-ray crystallography, in which a chemical sample is hit with X-rays that diffract off its atoms; the pattern of those diffracting X-rays reveals the 3-D structure of the targeted chemical. Often, this method is used to solve the structures of really big molecules, such as complex membrane proteins, but it can also be applied to small molecules. The challenge is that to perform this method a chemist must create good-sized chunks of crystal from a sample, which isn’t always easy. “I spent months once trying to get the right crystals for one of my samples,” says Stoltz.

    Another reliable method is NMR (nuclear magnetic resonance), which doesn’t require crystals but does require a relatively large amount of a sample, which can be hard to amass. Also, NMR provides only indirect structural information.

    Before now, MicroED—which is similar to X-ray crystallography but uses electrons instead of X-rays—was mainly used on crystallized proteins and not on small molecules. Co-author Tamir Gonen, an electron crystallography expert at UCLA who began developing the MicroED technique for proteins while at the Howard Hughes Medical Institute in Virginia, said that he only started thinking about using the method on small molecules after moving to UCLA and teaming up with Caltech.

    “Tamir had been using this technique on proteins, and just happened to mention that they can sometimes get it to work using only powdery samples of proteins,” says Hosea Nelson (PhD ’13), an assistant professor of chemistry and biochemistry at UCLA. “My mind was blown by this, that you didn’t have to grow crystals, and that’s around the time that the team started to realize that we could apply this method to a whole new class of molecules with wide-reaching implications for all types of chemistry.”

    The team tested several samples of varying qualities, without ever attempting to crystallize them, and were able to determine their structures thanks to the samples’ ample microcrystals. They succeeded in getting structures for ground-up samples of the brand-name drugs Tylenol and Advil, and they were able to identify distinct structures from a powdered mixture of four chemicals.

    The UCLA/Caltech team says it hopes this method will become routine in chemistry labs in the future.

    “In our labs, we have students and postdocs making totally new and unique molecular entities every day,” says Stoltz. “Now we have the power to rapidly figure out what they are. This is going to change synthetic chemistry.”

    The study was funded by the National Science Foundation, the National Institutes of Health, the Department of Energy, a Beckman Young Investigators award, a Searle Scholars award, a Pew Scholars award, the Packard Foundation, the Sloan Foundation, the Pew Charitable Trusts, and the Howard Hughes Medical Institute. Other co-authors include Christopher Jones,Michael Martynowycz, Johan Hattne, and Jose Rodriguez of UCLA; and Tyler Fulton of Caltech.

    See the full article here .


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    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus


    Caltech campus

     
  • richardmitnick 2:07 pm on November 12, 2018 Permalink | Reply
    Tags: A research team has adapted a powerful electron-based imaging technique to obtain an image of atomic-scale structure in a synthetic polymer., Before these high-resolution images the arrangement and variation of the different types of crystal structures was unknown, Chemistry, Cryogenic electron microscopy, Images of individual atoms in polymers had only been realized in computer simulations and illustrations, , , Peptoids are synthetically produced molecules that mimic biological molecules including chains of amino acids known as peptides, , Researchers achieved resolution of about 2 angstroms which is two-tenths of nanometer (billionth of a meter), Scientists Bring Polymers Into Atomic-Scale Focus, There are still mysteries about polymers at the atomic scale,   

    From Lawrence Berkeley National Lab and UC Berkeley: “Scientists Bring Polymers Into Atomic-Scale Focus” 

    Berkeley Logo

    From Lawrence Berkeley National Lab

    November 12, 2018
    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 486-5582

    1
    This image shows a rendering (gray and pink) of the molecular structure of a peptoid polymer that was studied by a team led by Berkeley Lab and UC Berkeley. The successful imaging of a polymer’s atomic-scale structure could inform new designs for plastics, like those that form the water bottles shown in the background. (Credit: Berkeley Lab, Charles Rondeau/PublicDomainPictures.net)

    From water bottles and food containers to toys and tubing, many modern materials are made of plastics. And while we produce about 110 million tons per year of synthetic polymers like polyethylene and polypropylene worldwide for these plastic products, there are still mysteries about polymers at the atomic scale.

    Because of the difficulty in capturing images of these materials at tiny scales, images of individual atoms in polymers have only been realized in computer simulations and illustrations, for example.

    Now, a research team led by Nitash Balsara, a senior faculty scientist in the Materials Sciences Division at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and professor of chemical and biomolecular engineering at UC Berkeley, has adapted a powerful electron-based imaging technique to obtain an image of atomic-scale structure in a synthetic polymer. The team included researchers from Berkeley Lab and UC Berkeley.

    The research could ultimately inform polymer fabrication methods and lead to new designs for materials and devices that incorporate polymers.

    In their study, published in the American Chemical Society’s Macromolecules journal, the researchers detail the development of a cryogenic electron microscopy imaging technique, aided by computerized simulations and sorting techniques, that identified 35 arrangements of crystal structures in a peptoid polymer sample. Peptoids are synthetically produced molecules that mimic biological molecules, including chains of amino acids known as peptides.

    2
    The simulated atomic-scale structure (top) and the averaged atomic-scale imaging (bottom) of a peptoid polymer sample. The sale bar is 10 angstroms, or 1 billionth of a meter. (Credit: Berkeley Lab, UC Berkeley)

    The sample was robotically synthesized at Berkeley Lab’s Molecular Foundry, a DOE Office of Science User Facility for nanoscience research. Researchers formed sheets of crystallized polymers measuring about 5 nanometers (billionths of a meter) in thickness when dispersed in water.

    “We conducted our experiments on the most perfect polymer molecules we could make,” Balsara said – the peptoid samples in the study were extremely pure compared to typical synthetic polymers.

    The research team created tiny flakes of peptoid nanosheets, froze them to preserve their structure, and then imaged them using an electron beam. An inherent challenge in imaging materials with a soft structure, such as polymers, is that the beam used to capture images also damages the samples.

    The direct cryogenic electron microscopy images, obtained using very few electrons to minimize beam damage, are too blurry to reveal individual atoms. Researchers achieved resolution of about 2 angstroms, which is two-tenths of nanometer (billionth of a meter), or about double the diameter of a hydrogen atom.

    They achieved this by taking over 500,000 blurry images, sorting different motifs into different “bins,” and averaging the images in each bin. The sorting methods they used were based on algorithms developed by the structural biology community to image the atomic structure of proteins.

    “We took advantage of technology that the protein-imaging folks had developed and extended it to human-made, soft materials,” Balsara said. “Only when we sorted them and averaged them did that blurriness become clear.”

    Before these high-resolution images, Balsara said, the arrangement and variation of the different types of crystal structures was unknown.

    “We knew that there were many motifs, but they are all different from each other in ways we didn’t know,” he said. “In fact, even the dominant motif in the peptoid sheet was a surprise.”

    3
    Researchers developed a colorized map (right) to show the distribution of different types of crystal structures (left) that they found in the polymer peptoid sample. The scale bar in the map image is 50 nanometers, or 50 billionths of a meter. (Credit: Berkeley Lab, UC Berkeley)

    Balsara credited Ken Downing, a senior scientist in Berkeley Lab’s Molecular Biophysics and Integrated Bioimaging Division who passed away in August, and Xi Jiang, a project scientist in the Materials Sciences Division, for capturing the high-quality images that were central to the study and for developing the algorithms necessary to achieve atomic resolution in the polymer imaging.

    Their expertise in cryogenic electron microscopy was complemented by Ron Zuckermann’s ability to synthesize model peptoids, David Prendergast’s knowledge of molecular dynamics simulations needed to interpret the images, Andrew Minor’s expertise in imaging metals at the atomic scale, and Balsara’s experience in the field of polymer science.

    At the Molecular Foundry, Zuckermann directs the Biological Nanostructures facility, Prendergast directs the Theory facility, and Minor directs the National Center for Electron Microscopy and is also a professor of materials science and engineering at UC Berkeley. Much of the cryo-electron imaging was carried out at UC Berkeley’s Krios microscopy facility.

    Balsara said that his own research into using polymers for batteries and other electrochemical devices could benefit from the research, as seeing the position of polymer atoms could greatly aid in the design of materials for these devices.

    Atomic-scale images of polymers used in everyday life may need more sophisticated, automated filtering mechanisms that rely on machine learning, for example.

    “We should be able to determine the atomic-scale structure of a wide variety of synthetic polymers such as commercial polyethylene and polypropylene, leveraging rapid developments in areas such as artificial intelligence, using this approach,” Balsara said.

    Determining crystal structures can provide vital information for other applications, such as the development of drugs, as different crystal motifs could produce quite different binding properties and therapeutic effects, for example.

    The work was conducted within the Soft Matter Electron Microscopy Program at Berkeley Lab, which is supported by the U.S. Department of Energy’s Office of Science; and by the Bay Area Cryo-EM Consortium.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Bringing Science Solutions to the World

    In the world of science, Lawrence Berkeley National Laboratory (Berkeley Lab) is synonymous with “excellence.” Thirteen Nobel prizes are associated with Berkeley Lab. Seventy Lab scientists are members of the National Academy of Sciences (NAS), one of the highest honors for a scientist in the United States. Thirteen of our scientists have won the National Medal of Science, our nation’s highest award for lifetime achievement in fields of scientific research. Eighteen of our engineers have been elected to the National Academy of Engineering, and three of our scientists have been elected into the Institute of Medicine. In addition, Berkeley Lab has trained thousands of university science and engineering students who are advancing technological innovations across the nation and around the world.

    Berkeley Lab is a member of the national laboratory system supported by the U.S. Department of Energy through its Office of Science. It is managed by the University of California (UC) and is charged with conducting unclassified research across a wide range of scientific disciplines. Located on a 202-acre site in the hills above the UC Berkeley campus that offers spectacular views of the San Francisco Bay, Berkeley Lab employs approximately 3,232 scientists, engineers and support staff. The Lab’s total costs for FY 2014 were $785 million. A recent study estimates the Laboratory’s overall economic impact through direct, indirect and induced spending on the nine counties that make up the San Francisco Bay Area to be nearly $700 million annually. The Lab was also responsible for creating 5,600 jobs locally and 12,000 nationally. The overall economic impact on the national economy is estimated at $1.6 billion a year. Technologies developed at Berkeley Lab have generated billions of dollars in revenues, and thousands of jobs. Savings as a result of Berkeley Lab developments in lighting and windows, and other energy-efficient technologies, have also been in the billions of dollars.

    Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a UC Berkeley physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.

    A U.S. Department of Energy National Laboratory Operated by the University of California.

    University of California Seal

    DOE Seal

     
  • richardmitnick 7:22 pm on November 9, 2018 Permalink | Reply
    Tags: , , , , , , , , Chemistry, , , , , , Understanding our own backyard will be key in interpreting data from far-flung exoplanets   

    From COSMOS Magazine: “The tech we’re going to need to detect ET” 

    Cosmos Magazine bloc

    From COSMOS Magazine

    09 November 2018
    Lauren Fuge

    1
    Searching for biosignatures rather than examples of life itself is considered a prime strategy in the hunt for ET. smartboy10/Getty Images

    Move over Mars rovers, new technologies to detect alien life are on the horizon.

    A group of scientists from around the world, led by astrochemistry expert Chaitanya Giri from the Tokyo Institute of Technology in Japan, have put their heads together to plan the next 20 years’ worth of life-detection technologies. The study is currently awaiting peer review, but is freely available on the pre-print site, ArXiv.

    For decades, astrobiologists have scoured the skies and the sands of other planets for hints of extraterrestrial life. Not only are these researchers trying to find ET, but they’re also aiming to learn about the origin and evolution of life on Earth, the chemical composition of organic extraterrestrial objects, what makes a planet or satellite habitable, and more.

    But the answers to such questions are preceded by long years of planning, development, problem-solving and strategising.

    Late in 2017, 20 scientists from Japan, India, France, Germany and the USA – each with a special area of expertise – came together at a workshop run by the Earth-Life Science Institute (ELSI) at Giri’s Tokyo campus. There, they discussed the current progress and enticing possibilities of life-detection technologies.

    In particular, the boffins debated which ones should be a priority for research and development for missions within the local solar system – in other words, which instruments will be most feasible to out onto a space probe and send off to Mars or Enceladus during the next couple of decades.

    Of course, the planets and moons in the solar system are an extremely limited sample of the number of potentially habitable worlds in the universe, but understanding our own backyard will be key in interpreting data from far-flung exoplanets.

    So, according to these astrobiology experts, what’s the future plan for alien detection?

    The first step of any space mission is to study the planet or satellite from afar to determine whether it is habitable. Luckily, an array of next-generation telescopes is currently being built, from the ultra-sensitive James Webb Space Telescope, slated for launch in 2021, to the gargantuan Extremely Large Telescope in Chile, which will turn its 39-metre eye to the sky in 2024. The authors point out that observatories such as these will vastly expand our theoretical knowledge of planet habitability.

    NASA/ESA/CSA Webb Telescope annotated

    ESO/E-ELT,to be on top of Cerro Armazones in the Atacama Desert of northern Chile. located at the summit of the mountain at an altitude of 3,060 metres (10,040 ft).

    Just because a world is deemed habitable doesn’t mean life will be found all over it, though. It may exist only in limited geographical niches. To reach these inaccessible sites, the paper argues that we will require “agile robotic probes that are robust, able to seamlessly communicate with orbiters and deep space communications networks, be operationally semi-autonomous, have high-performance energy supplies, and are sterilisable to avoid forward contamination”.

    But according to Elizabeth Tasker, associate professor at the Japan Aerospace Exploration Agency (JAXA), who was not involved in the study, getting there is only half the struggle.

    “In fact, it’s the most tractable half because we can picture the problems we will face,” she says.

    The second, more pressing issue is how to recognise life unlike anything we know on Earth.

    As Tasker explains: “We only have Earth life to compare to and this is the result of huge evolutionary history on a planet whose complex past is unlikely to be replicated closely. That’s a lot of baggage to separate out.”

    According to the paper, the way forward is to equip missions with a suite of life-detection instruments that don’t look for life as we know it, but are instead able to identify the kinds of features that make organisms function.

    The authors outline a huge variety of exciting technologies that could be used for this purpose, including spectroscopy techniques (to analyse potential biological materials), quantum tunnelling [Nature Nanotechnology
    ] (to find DNA, RNA, peptides, and other small molecules), and fluorescence microscopy [ https://www.hou.usra.edu/meetings/lpsc2014/pdf/2744.pdf ](to identify the presence of cell membranes).

    They also nominate different forms of gas chromatography (to spot amino acids and sugars formed by living organisms, plus checking to see if molecules are “homochiral” [Space Science Reviews] (a suspected biosignature) using microfluidic devices and microscopes.

    High-resolution, miniaturised mass spectrometers would also be helpful, characterising biopolymers, which are created by living organisms, and measuring the elemental composition of objects to aid isotopic dating.

    Giri and colleagues also stress that exciting developments in machine learning, artificial intelligence, and pattern recognition will be useful in determining whether chemical samples are biological in origin.

    Interestingly, researchers are also developing technologies that may allow the detection of life in more unconventional places. On Earth, for example, cryotubes were recently used [International Journal of Systematic and Evolutionary Microbiology] to discover several new species of bacteria in the upper atmosphere.

    The scientists also discuss how certain technologies – such as high-powered synchrotron radiation and magnetic field facilities – are not yet compact enough to fly to other planets, and so samples must continue to be brought back for analysis.

    Several sample-and-return missions are currently underway, including JAXA’s Martian Moons exploration mission to Phobos, Hayabusa-2 to asteroid Ryugu, and NASA’s OSIRIS-rex to asteroid Bennu. What we learn from handling the organic-rich extraterrestrial materials brought back from these trips will be invaluable.

    JAXA MMX spacecraft

    JAXA/Hayabusa 2 Credit: JAXA/Akihiro Ikeshita

    NASA OSIRIS-REx Spacecraft

    What we learn from handling the organic-rich extraterrestrial materials brought back from these trips will be invaluable.

    The predictions and recommendations put forward by Giri and colleagues are the first steps in getting these technologies discussed in panel reviews, included in decadal surveys, and eventually funded.

    They complement several similar efforts, including a report prepared by US National Academies of Science, Engineering and Medicine (NASEM), calling for an expansion of the range of possible ET indicators, and a US-led exploration of how the next generation of radio telescopes will be utilised by SETI.

    Perhaps most importantly, these papers all highlight the need for collaborative work between scientists across disciplines.

    “A successful detection of life will need astrophysicists and geologists to examine possible environments on other planets, engineers and physicists to design the missions and instruments that can collect data, and chemists and biologists to determine how to classify life,” JAXA’s Tasker says.

    “But maybe that is appropriate: finding out what life really is and where it can flourish is the story of everyone on Earth. It should take all of us to unravel.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 1:50 pm on November 7, 2018 Permalink | Reply
    Tags: , , Chemistry, , , , , Researchers create most complete high-res atomic movie of photosynthesis to date, , ,   

    From SLAC National Accelerator Lab: “Researchers create most complete high-res atomic movie of photosynthesis to date” 

    From SLAC National Accelerator Lab

    November 7, 2018

    Andrew Gordon
    agordon@slac.stanford.edu
    (650) 926-2282

    In a major step forward, SLAC’s X-ray laser captures all four stable states of the process that produces the oxygen we breathe, as well as fleeting steps in between. The work opens doors to understanding the past and creating a greener future.

    1
    Using SLAC’s X-ray laser, researchers have captured the most complete high-res atomic movie to date of Photosystem II, a key protein complex in plants, algae and cyanobacteria responsible for splitting water and producing the oxygen we breathe. (Gregory Stewart, SLAC National Accelerator Laboratory)

    Despite its role in shaping life as we know it, many aspects of photosynthesis remain a mystery. An international collaboration between scientists at SLAC National Accelerator Laboratory, Lawrence Berkeley National Laboratory and several other institutions is working to change that. The researchers used SLAC’s Linac Coherent Light Source (LCLS) X-ray laser to capture the most complete and highest-resolution picture to date of Photosystem II, a key protein complex in plants, algae and cyanobacteria responsible for splitting water and producing the oxygen we breathe. The results were published in Nature today.

    SLAC/LCLS

    Explosion of life

    When Earth formed about 4.5 billion years ago, the planet’s landscape was almost nothing like what it is today. Junko Yano, one of the authors of the study and a senior scientist at Berkeley Lab, describes it as “hellish.” Meteors sizzled through a carbon dioxide-rich atmosphere and volcanoes flooded the surface with magmatic seas.

    Over the next 2.5 billion years, water vapor accumulating in the air started to rain down and form oceans where the very first life appeared in the form of single-celled organisms. But it wasn’t until one of those specks of life mutated and developed the ability to harness light from the sun and turn it into energy, releasing oxygen molecules from water in the process, that Earth started to evolve into the planet it is today. This process, oxygenic photosynthesis, is considered one of nature’s crown jewels and has remained relatively unchanged in the more than 2 billion years since it emerged.

    “This one reaction made us as we are, as the world. Molecule by molecule, the planet was slowly enriched until, about 540 million years ago, it exploded with life,” said co-author Uwe Bergmann, a distinguished staff scientist at SLAC. “When it comes to questions about where we come from, this is one of the biggest.”

    A greener future

    Photosystem II is the workhorse responsible for using sunlight to break water down into its atomic components, unlocking hydrogen and oxygen. Until recently, it had only been possible to measure pieces of this process at extremely low temperatures. In a previous paper, the researchers used a new method to observe two steps of this water-splitting cycle [Nature]at the temperature at which it occurs in nature.

    Now the team has imaged all four intermediate states of the process at natural temperature and the finest level of detail yet. They also captured, for the first time, transitional moments between two of the states, giving them a sequence of six images of the process.

    The goal of the project, said co-author Jan Kern, a scientist at Berkeley Lab, is to piece together an atomic movie using many frames from the entire process, including the elusive transient state at the end that bonds oxygen atoms from two water molecules to produce oxygen molecules.

    “Studying this system gives us an opportunity to see how metals and proteins work together and how light controls such kinds of reactions,” said Vittal Yachandra, one of the authors of the study and a senior scientist at Berkeley Lab who has been working on Photosystem II for more than 35 years. “In addition to opening a window on the past, a better understanding of Photosystem II could unlock the door to a greener future, providing us with inspiration for artificial photosynthetic systems that produce clean and renewable energy from sunlight and water.”

    Sample assembly line

    For their experiments, the researchers grow what Kern described as a “thick green slush” of cyanobacteria — the very same ancient organisms that first developed the ability to photosynthesize — in a large vat that is constantly illuminated. They then harvest the cells for their samples.

    At LCLS, the samples are zapped with ultrafast pulses of X-rays [Science] to collect both X-ray crystallography and spectroscopy data to map how electrons flow in the oxygen-evolving complex of photosystem II. In crystallography, researchers use the way a crystal sample scatters X-rays to map its structure; in spectroscopy, they excite the atoms in a material to uncover information about its chemistry. This approach, combined with a new assembly-line sample transportation system [Nature Methods], allowed the researchers to narrow down the proposed mechanisms put forward by the research community over the years.

    Mapping the process

    Previously, the researchers were able to determine the room-temperature structure of two of the states at a resolution of 2.25 angstroms; one angstrom is about the diameter of a hydrogen atom. This allowed them to see the position of the heavy metal atoms, but left some questions about the exact positions of the lighter atoms, like oxygen. In this paper, they were able to improve the resolution even further, to 2 angstroms, which enabled them to start seeing the position of lighter atoms more clearly, as well as draw a more detailed map of the chemical structure of the metal catalytic center in the complex where water is split.

    This center, called the oxygen-evolving complex, is a cluster of four manganese atoms and one calcium atom bridged with oxygen atoms. It cycles through the four stable oxidation states, S0-S3, when exposed to sunlight. On a baseball field, S0 would be the start of the game when a player on home base is ready to go to bat. S1-S3 would be players on first, second, and third. Every time a batter connects with a ball, or the complex absorbs a photon of sunlight, the player on the field advances one base. When the fourth ball is hit, the player slides into home, scoring a run or, in the case of Photosystem II, releasing breathable oxygen.

    The researchers were able to snap action shots of how the structure of the complex transformed at every base, which would not have been possible without their technique. A second set of data allowed them to map the exact position of the system in each image, confirming that they had in fact imaged the states they were aiming for.

    1
    In photosystem II, the water-splitting center cycles through four stable states, S0-S3. On a baseball field, S0 would be the start of the game when a batter on home base is ready to hit. S1-S3 would be players waiting on first, second, and third. The center gets bumped up to the next state every time it absorbs a photon of sunlight, just like how a player on the field advances one base every time a batter connects with a ball. When the fourth ball is hit, the player slides into home, scoring a run or, in the case of Photosystem II, releasing the oxygen we breathe. (Gregory Stewart/SLAC National Accelerator Laboratory)

    Sliding into home

    But there are many other things going on throughout this process, as well as moments between states when the player is making a break for the next base, that are a bit harder to catch. One of the most significant aspects of this paper, Yano said, is that they were able to image two moments in between S2 and S3. In upcoming experiments, the researchers hope to use the same technique to image more of these in-between states, including the mad dash for home — the transient state, or S4, where two atoms of oxygen bond together — providing information about the chemistry of the reaction that is vital to mimicking this process in artificial systems.

    “The entire cycle takes nearly two milliseconds to complete,” Kern said. “Our dream is to capture 50-microsecond steps throughout the full cycle, each of them with the highest resolution possible, to create this atomic movie of the entire process.”

    Although they still have a way to go, the researchers said that these results provide a path forward, both in unveiling the mysteries of how photosynthesis works and in offering a blueprint for artificial sources of renewable energy.

    “It’s been a learning process,” said SLAC scientist and co-author Roberto Alonso-Mori. “Over the last seven years we’ve worked with our collaborators to reinvent key aspects of our techniques. We’ve been slowly chipping away at this question and these results are a big step forward.”

    In addition to SLAC and Berkeley Lab, the collaboration includes researchers from Umeå University, Uppsala University, Humboldt University of Berlin, the University of California, Berkeley, the University of California, San Francisco and the Diamond Light Source.

    Key components of this work were carried out at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), Berkeley Lab’s Advanced Light Source (ALS) and Argonne National Laboratory’s Advanced Photon Source (APS). LCLS, SSRL, APS, and ALS are DOE Office of Science user facilities. This work was supported by the DOE Office of Science and the National Institutes of Health, among other funding agencies.

    SLAC/SSRL

    LBNL/ALS

    ANL APS

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

     
  • richardmitnick 11:39 am on November 7, 2018 Permalink | Reply
    Tags: Acoustic phonons, , , Chemistry, Dancing atoms in perovskite materials provide insight into how solar cells work, , , ,   

    From SLAC National Accelerator Lab: “Dancing atoms in perovskite materials provide insight into how solar cells work” 

    From SLAC National Accelerator Lab

    November 6, 2018
    Ali Sundermier

    1
    When the researchers scattered neutrons off the perovskite material (red beam) they were able to measure the energy the neutrons lost or gained (white and blue lines). Using this information, they were able to see the structure and motion of the atoms and molecules within the material (arrangement of blue and purple spheres). (Greg Stewart/SLAC National Accelerator Laboratory)

    A new study is a step forward in understanding why perovskite materials work so well in energy devices and potentially leads the way toward a theorized “hot” technology that would significantly improve the efficiency of today’s solar cells.

    A closer look at materials that make up conventional solar cells reveals a nearly rigid arrangement of atoms with little movement. But in hybrid perovskites, a promising class of solar cell materials, the arrangements are more flexible and atoms dance wildly around, an effect that impacts the performance of the solar cells but has been difficult to measure.

    In a paper published in the PNAS, an international team of researchers led by the U.S. Department of Energy’s SLAC National Accelerator Laboratory has developed a new understanding of those wild dances and how they affect the functioning of perovskite materials. The results could explain why perovskite solar cells are so efficient and aid the quest to design hot-carrier solar cells, a theorized technology that would almost double the efficiency limits of conventional solar cells by converting more sunlight into usable electrical energy.

    Piece of the puzzle

    Perovskite solar cells, which can be produced at room temperature, offer a less expensive and potentially better performing alternative to conventional solar cell materials like silicon, which have to be manufactured at extremely high temperatures to eliminate defects. But a lack of understanding about what makes perovskite materials so efficient at converting sunlight into electricity has been a major hurdle to producing even higher efficiency perovskite solar cells.

    “It’s really only been over the last five or six years that people have developed this intense interest in solar perovskite materials,” says Mike Toney, a distinguished staff scientist at SLAC’s Stanford Synchrotron Radiation Light Source (SSRL) who led the study.

    SLAC/SSRL

    “As a consequence, a lot of the foundational knowledge about what makes the materials work is missing. In this research, we provided an important piece of this puzzle by showing what sets them apart from more conventional solar cell materials. This provides us with scientific underpinnings that will allow us to start engineering these materials in a rational way.”

    Keeping it hot

    When sunlight hits a solar cell, some of the energy can be used to kick electrons in the material up to higher energy states. These higher-energy electrons are funneled out of the material, producing electricity.

    But before this happens, a majority of the sun’s energy is lost to heat with some fraction also lost during the extraction of usable energy or due to inefficient light collection. In many conventional solar cells, such as those made with silicon, acoustic phonons – a sort of sound wave that propagates through material – are the primary way that this heat is carried through the material. The energy lost by the electron as heat limits the efficiency of the solar cell.

    In this study, theorists from the United Kingdom, led by Imperial College Professor Aron Walsh and electronic structure theorists Jonathan Skelton and Jarvist Frost, provided a theoretical framework for interpreting the experimental results. They predicted that acoustic phonons traveling through perovskites would have short lifetimes as a result of the flexible arrangements of dancing atoms and molecules in the material.

    Stanford chemists Hema Karunadasa and Ian Smith were able to grow the large, specialized single crystals that were essential for this work. With the help of Peter Gehring, a physicist at the NIST Center for Neutron Research, the team scattered neutrons off these perovskite single crystals in a way that allowed them to retrace the motion of the atoms and molecules within the material. This allowed them to precisely measure the lifetime of the acoustic phonons.

    The research team found that in perovskites, acoustic phonons are incredibly short-lived, surviving for only 10 to 20 trillionths of a second. Without these phonons trucking heat through the material, the electrons might stay hot and hold onto their energy as they’re pulled out of the material. Harnessing this effect could potentially lead to hot-carrier solar cells with efficiencies that are nearly twice as high as conventional solar cells.

    In addition, this phenomenon could explain how perovskite solar cells work so well despite the material being riddled with defects that would trap electrons and dampen performance in other materials.

    “Since phonons in perovskites don’t travel very far, they end up heating the area surrounding the electrons, which might provide the boost the electrons need to escape the traps and continue on their merry way,” Toney says.

    Transforming energy production

    To follow up on this study, researchers at the Center for Hybrid Organic-Inorganic Semiconductors for Energy (CHOISE) Energy Frontier Research Center led by DOE’s National Renewable Energy Laboratory will investigate this phenomenon in more complicated perovskite materials that are shown to be more efficient in energy devices. They would like to figure out how changing the chemical make-up of the material affects acoustic phonon lifetimes.

    “We need to fundamentally transform our energy system as quickly as possible,” says Aryeh Gold-Parker, who co-led the study as a PhD student at Stanford University and SLAC. “As we move toward a low-carbon future, a very important piece is having cheap and efficient solar cells. The hope in perovskites is that they’ll lead to commercial solar panels that are more efficient and cheaper than the ones on the market today.”

    The research team also included scientists from NIST; the University of Bath and Kings College London, both in the UK; and Yonsei University in Korea.

    SSRL is a DOE Office of Science user facility. This work was supported by the DOE’s Office of Science and the Solar Energy Technologies Office; the Engineering and Physical Sciences Research Council; the Royal Society; and the Leverhulme Trust.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.

    Stem Education Coalition

    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.

     
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