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  • richardmitnick 2:06 pm on December 12, 2017 Permalink | Reply
    Tags: Electric car makers are intensely interested in lithium-rich battery cathodes that could significantly increase driving range, , Scientists Discover Path to Improving Game-Changing Battery Electrode, , SLAC Stanford SSRL   

    From SLAC: “Scientists Discover Path to Improving Game-Changing Battery Electrode” 


    SLAC Lab

    Electric car makers are intensely interested in lithium-rich battery cathodes that could significantly increase driving range. A new study opens a path to making them live up to their promise.

    1
    Electric car makers are intensely interested in lithium-rich battery cathodes that could significantly increase driving range. A new study opens a path to making them live up to their promise. (Stanford University/3Dgraphic)

    2
    SLAC and Stanford researchers at an SSRL beamline used for battery research. From left: SLAC staff scientists Apurva Mehta and Kevin Stone; Stanford graduate students Will Gent and Kipil Lim; and SLAC distinguished staff scientist Mike Toney. (Dawn Harmer/SLAC National Accelerator Laboratory)

    December 12, 2017
    If you add more lithium to the positive electrode of a lithium-ion battery – overstuff it, in a sense ­– it can store much more charge in the same amount of space, theoretically powering an electric car 30 to 50 percent farther between charges. But these lithium-rich cathodes quickly lose voltage, and years of research have not been able to pin down why – until now.

    After looking at the problem from many angles, researchers from Stanford University, two Department of Energy national labs and the battery manufacturer Samsung created a comprehensive picture of how the same chemical processes that give these cathodes their high capacity are also linked to changes in atomic structure that sap performance.

    “This is good news,” said William E. Gent, a Stanford University graduate student and Siebel Scholar who led the study. “It gives us a promising new pathway for optimizing the voltage performance of lithium-rich cathodes by controlling the way their atomic structure evolves as a battery charges and discharges.”

    Michael Toney, a distinguished staff scientist at SLAC National Accelerator Laboratory and a co-author of the paper, added, “It is a huge deal if you can get these lithium-rich electrodes to work because they would be one of the enablers for electric cars with a much longer range. There is enormous interest in the automotive community in developing ways to implement these, and understanding what the technological barriers are may help us solve the problems that are holding them back.”

    The team’s report appears today in Nature Communications.

    The researchers studied the cathodes with a variety of X-ray techniques at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) and Lawrence Berkeley National Laboratory’s Advanced Light Source (ALS).

    SLAC/SSRL

    LBNL/ALS

    Theorists from Berkeley Lab’s Molecular Foundry, led by David Prendergast, were also involved, helping the experimenters understand what to look for and explain their results.

    The cathodes themselves were made by Samsung Advanced Institute of Technology using commercially relevant processes, and assembled into batteries similar to those in electric vehicles.

    “This ensured that our results represented an understanding of a cutting-edge material that would be directly relevant for our industry partners,” Gent said. As an ALS doctoral fellow in residence, he was involved in both the experiments and the theoretical modelling for the study.

    See the full article here .

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    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 10:37 am on November 29, 2017 Permalink | Reply
    Tags: , , Dnm1 proteins, , , SLAC Stanford SSRL, , UCLA bioengineers discover mechanism that regulates cells’ ‘powerhouses’   

    From UCLA Newsroom: “UCLA bioengineers discover mechanism that regulates cells’ ‘powerhouses’” 


    UCLA Newsroom

    November 27, 2017
    Matthew Chin

    1
    In this artist’s rendering, Dnm1 proteins surrounding a mitochondrion are breaking it up into two. Jaime de Anda/ACS Central Science.

    UCLA bioengineers and their colleagues have discovered a new perspective on how cells regulate the sizes of mitochondria, the parts of cells that provide energy, by cutting them into smaller units.

    The researchers wrote that this finding, demonstrated with yeast proteins, could eventually be used to help address human diseases associated with an imbalanced regulation of mitochondria size — for example, Alzheimer’s or Parkinson’s diseases. In addition, since having mitochondria that are too small or too large can potentially lead to incurable diseases, it is conceivable that the proteins responsible for this process could be potential targets for future therapies.

    The study was published in ACS Central Science and was led by UCLA bioengineering professor Gerard Wong.

    Inside the cell, mitochondria resemble the long balloons used to create balloon animals. If the mitochondria are too long, they can get tangled. Their sizes are known to be primarily regulated by two proteins, one of which breaks up longer mitochondria into smaller sizes. They are known as cells’ “powerhouses” as they convert chemical energy from food into a form useful for cells to perform all their functions.

    Keeping mitochondria at optimal sizes is important to cells’ health. An insufficient amount of the regulating protein, known as Dnm1, results in the mitochondria getting too long and tangled. Too much Dnm1 results in too many short mitochondria. In both cases, the mitochondria are rendered essentially ineffective as power providers for the cell. This situation could lead to neurodevelopmental disorders or neurodegenerative diseases, such as Alzheimer’s or Parkinson’s.

    To better understand this mechanism, the researchers used a machine-learning approach they developed in 2016 to figure out exactly how the proteins break up one mitrochondrion into two smaller ones. They also used a powerful technique called “synchrotron small-angle X-ray scattering” at the Stanford Synchrotron Radiation Lightsource, a U.S. Department of Energy research facility, to see how these proteins deform mitochondrial membranes during this process.

    SLAC/SSRL

    Before this study, it was thought that these proteins encircled the mitochondria, then cut it in two by simply squeezing tightly. The process, the team discovered, is more subtle.

    “When Dnm1 wraps around mitochondria, it has been previously shown that the protein physically tightens and pinches,” said Michelle Lee, a recent UCLA bioengineering doctoral graduate who was advised by Wong and is one of two lead authors of the study. “What we found is that when Dnm1 contacts the mitochondrial surface, it also makes that area of the mitochondrion itself more moldable and easier to undergo cleavage. These two effects work hand in hand to make the process of mitochondrial division efficient.”

    The other lead author is Ernest Lee, a graduate student in the UCLA-Caltech Medical Scientist Training Program and a bioengineering graduate student also advised by Wong. He carried out the computational analyses for the experiment.

    “Using our machine-learning tool, we were able to discover hidden membrane-remodeling activity in Dnm1, consistent with our X-ray studies,” Lee said. “Interestingly, by analyzing distant relatives of Dnm1, we found that the protein gradually evolved this ability over time.”

    “This is a very unexpected result — no one thought these molecules would have a split personality, with both personalities necessary for the biological function,” said Wong, who is also a UCLA professor of chemistry and biochemistry and is a member of the California NanoSystems Institute. “The multifunctional behavior we identified may be the rule rather than the exception for proteins.”

    Other authors include Andy Ferguson from the University of Illinois at Urbana-Champaign and Blake Hill from the Medical College of Wisconsin.

    The research was supported by the National Science Foundation and the National Institutes of Health, with additional support from the Department of Energy for imaging experiments.

    See the full article here .

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    UC LA Campus

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

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

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

     
  • richardmitnick 8:03 am on September 1, 2017 Permalink | Reply
    Tags: , , Nanocrystals rapidly forming superlattices while they are themselves still growing, , , Scientists Watch ‘Artificial Atoms’ Assemble into Perfect Lattices with Many Uses, SLAC Stanford SSRL, Superlattices can form superfast   

    From SLAC: “Scientists Watch ‘Artificial Atoms’ Assemble into Perfect Lattices with Many Uses” 


    SLAC Lab

    July 31, 2017
    Andrew Gordon
    agordon@slac.stanford.edu
    (650) 926-2282
    Written by Glennda Chui

    1
    An illustration shows nanocrystals assembling into an ordered ‘superlattice’ – a process that a SLAC/Stanford team was able to observe in real time with X-rays from the Stanford Synchrotron Radiation Lightsource (SSRL). They discovered that this assembly takes just a few seconds when carried out in hot solutions. The results open the door for rapid self-assembly of nanocrystal building blocks into complex structures with applications in optoelectronics, solar cells, catalysis and magnetic materials. (Greg Stewart/SLAC National Accelerator Laboratory)

    A serendipitous discovery lets researchers spy on this self-assembly process for the first time with SLAC’s X-ray synchrotron. What they learn will help them fine-tune precision materials for electronics, catalysis and more.

    Some of the world’s tiniest crystals are known as “artificial atoms” because they can organize themselves into structures that look like molecules, including “superlattices” that are potential building blocks for novel materials.

    Now scientists from the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have made the first observation of these nanocrystals rapidly forming superlattices while they are themselves still growing. What they learn will help scientists fine-tune the assembly process and adapt it to make new types of materials for things like magnetic storage, solar cells, optoelectronics and catalysts that speed chemical reactions.

    The key to making it work was the serendipitous discovery that superlattices can form superfast – in seconds rather than the usual hours or days – during the routine synthesis of nanocrystals. The scientists used a powerful beam of X-rays at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) to observe the growth of nanocrystals and the rapid formation of superlattices in real time.

    SLAC/SSRL

    A paper describing the research, which was done in collaboration with scientists at the DOE’s Argonne National Laboratory, was published today in Nature.

    “The idea is to see if we can get an independent understanding of how these superlattices grow so we can make them more uniform and control their properties,” said Chris Tassone, a staff scientist at SSRL who led the study with Matteo Cargnello, assistant professor of chemical engineering at Stanford.

    Tiny Crystals with Outsized Properties

    2
    Stanford Assistant Professor Matteo Cargnello at a lab in the Stanford Chemical Engineering Department where nanocrystals are grown. Cargnello and Chris Tassone, a staff scientist at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), led a team that discovered how superlattices can grow unexpectedly fast – in seconds, rather than hours or days – during routine nanocrystal synthesis. (Dawn Harmer/SLAC National Accelerator Laboratory)

    Scientists have been making nanocrystals in the lab since the 1980s. Because of their tiny size –they’re billionths of a meter wide and contain just 100 to 10,000 atoms apiece — they are governed by the laws of quantum mechanics, and this gives them interesting properties that can be changed by varying their size, shape and composition. For instance, spherical nanocrystals known as quantum dots, which are made of semiconducting materials, glow in colors that depend on their size; they are used in biological imaging and most recently in high-definition TV displays.

    In the early 1990s, researchers started using nanocrystals to build superlattices, which have the ordered structure of regular crystals, but with small particles in place of individual atoms. These, too, are expected to have unusual properties that are more than the sum of their parts.

    But until now, superlattices have been grown slowly at low temperatures, sometimes in a matter of days.

    That changed in February 2016, when Stanford postdoctoral researcher Liheng Wu serendipitously discovered that the process can occur much faster than scientists had thought.

    3
    The experimental set-up at SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) where scientists used an X-ray beam to observe superlattices forming during the synthesis of nanocrystals for the first time. The vessel where the reactions took place is at bottom center, wrapped in gold heating tape that boosted the temperature inside to more than 230 degrees Celsius. (Liheng Wu/Stanford University)

    ‘Something Weird Is Happening’

    He was trying to make nanocrystals of palladium – a silvery metal that’s used to promote chemical reactions in catalytic converters and many industrial processes – by heating a solution containing palladium atoms to more than 230 degrees Celsius. The goal was to understand how these tiny particles form, so their size and other properties could be more easily adjusted.

    The team added small windows to a reaction chamber about the size of a tangerine so they could shine an SSRL X-ray beam through it and watch what was happening in real time.

    “It’s kind of like cooking,” Cargnello explained. “The reaction chamber is like a pan. We add a solvent, which is like the frying oil; the main ingredients for the nanocrystals, such as palladium; and condiments, which in this case are surfactant compounds that tune the reaction conditions so you can control the size and composition of the particles. Once you add everything to the pan, you heat it up and fry your stuff.”

    Wu and Stanford graduate student Joshua Willis expected to see the characteristic pattern made by X-rays scattering off the tiny particles. They saw a completely different pattern instead.

    “So something weird is happening,” they texted their adviser.

    The something weird was that the palladium nanocrystals were assembling into superlattices.

    A Balance of Forces

    At this point, “The challenge was to understand what brings the particles together and attracts them to each other but not too strongly, so they have room to wiggle around and settle into an ordered position,” said Jian Qin, an assistant professor of chemical engineering at Stanford who performed theoretical calculations to better understand the self-assembly process.

    Once the nanocrystals form, what seems to be happening is that they acquire a sort of hairy coating of surfactant molecules. The nanocrystals glom together, attracted by weak forces between their cores, and then a finely tuned balance of attractive and repulsive forces between the dangling surfactant molecules holds them in just the right configuration for the superlattice to grow.

    To the scientists’ surprise, the individual nanocrystals then kept on growing, along with the superlattices, until all the chemical ingredients in the solution were used up, and this unexpected added growth made the material swell. The researchers said they think this occurs in a wide range of nanocrystal systems, but had never been seen because there was no way to observe it in real time before the team’s experiments at SSRL.

    “Once we understood this system, we realized this process may be more general than we initially thought,” Wu said. “We have demonstrated that it’s not only limited to metals, but it can also be extended to semiconducting materials and very likely to a much larger set of materials.”

    The team has been doing follow-up experiments to find out more about how the superlattices grow and how they can tweak the size, composition and properties of the finished product.

    Ian Salmon McKay, a graduate student in chemical engineering at Stanford, and Benjamin T. Diroll, a postdoctoral researcher at Argonne National Laboratory’s Center for Nanoscale Materials (CNM), also contributed to the work.

    SSRL and CNM are DOE Office of Science User Facilities. The research was funded by the DOE Office of Science and by a Laboratory Directed Research and Development grant from SLAC.

    See the full article here .

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  • richardmitnick 9:23 pm on April 11, 2017 Permalink | Reply
    Tags: , , , , , , SLAC Stanford SSRL, Theory Institute for Materials and Energy Spectroscopies (TIMES), ,   

    From SLAC: “New SLAC Theory Institute Aims to Speed Research on Exotic Materials at Light Sources” 


    SLAC Lab

    April 11, 2017
    Glennda Chui

    A new institute at the Department of Energy’s SLAC National Accelerator Laboratory is using the power of theory to search for new types of materials that could revolutionize society – by making it possible, for instance, to transmit electricity over power lines with no loss.

    The Theory Institute for Materials and Energy Spectroscopies (TIMES) focuses on improving experimental techniques and speeding the pace of discovery at West Coast X-ray facilities operated by SLAC and by Lawrence Berkeley National Laboratory, its DOE sister lab across the bay.

    But the institute aims to have a much broader impact on studies aimed at developing new materials for energy and other technological applications by making the tools it develops available to scientists around the world.

    TIMES opened in August 2016 as part of the Stanford Institute for Materials and Energy Sciences (SIMES), a DOE-funded institute operated jointly with Stanford.

    Materials that Surprise

    “We’re interested in materials with remarkable properties that seem to emerge out of nowhere when you arrange them in particular ways or squeeze them down into a single, two-dimensional layer,” says Thomas Devereaux, a SLAC professor of photon science who directs both TIMES and SIMES.

    This general class of materials is known as “quantum materials.” Some of the best-known examples are high-temperature superconductors, which conduct electricity with no loss; topological insulators, which conduct electricity only along their surfaces; and graphene, a form of pure carbon whose superior strength, electrical conductivity and other surprising qualities derive from the fact that it’s just one layer of atoms thick.

    In another research focus, Devereaux says, “We want to see what happens when you push materials far beyond their resting state – out of equilibrium, is the way we put it – by exciting them in various ways with pulses of X-ray light at facilities known as light sources.

    “This tells you how materials will behave under realistic operating conditions, for instance in a lightweight airplane or a new type of battery. Understanding and controlling out-of-equilibrium behavior and learning how novel properties emerge in complex materials are two of the scientific grand challenges in our field, and light sources are ideal places to do this work.”

    Joining Forces With Light Sources

    A key part of the institute’s work is to use theory and computation to improve experimental techniques – especially X-ray spectroscopy, which probes the chemical composition and electronic structure of materials – in order to make research at light sources more productive.

    “We are in a golden age of X-ray spectroscopy, in which many billions of dollars have been invested worldwide to develop new X-ray and neutron sources that allow us to study very small details and very fast processes in materials,” Devereaux says. “In fact, we are on the threshold of being able to control matter at a much deeper level than ever possible before.

    “But while X-ray spectroscopy has a long history of collaboration between experimentalists and theorists, there has not been a companion theory institute anywhere. TIMES fills this gap. It aims to solidify collaboration and development of new methods and tools for theory relevant to this new landscape.”

    Devereaux, a theorist who uses computation to study quantum materials, came to SLAC 10 years ago from the University of Waterloo in Canada to work more closely with researchers at three light sources – SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL), Berkeley Lab’s Advanced Light Source (ALS) and the Linac Coherent Light Source (LCLS), the world’s first X-ray free-electron laser, which at the time was under construction at SLAC. Opened for research in 2009, LCLS gives scientists access to pulses a billion times brighter than any available before and that arrive up to 120 times per second, opening whole new avenues for research.

    SLAC/SSRL

    LBNL/ALS

    SLAC LCLS

    SLAC/LCLS II

    With LCLS, Devereaux says, “It became clear that we had an unprecedented opportunity to study materials that have been pushed farther away from equilibrium than was ever possible before.”

    Basic Questions and Practical Answers

    The DOE-funded theory institute has hired two staff scientists, Chunjing Jia and Das Pemmaraju, and works closely with SLAC staff scientists Brian Moritz and Hongchen Jiang and with a number of scientists at the three light sources.

    “We have two main goals,” Jia says. “One is to use X-ray spectroscopy and other techniques to look at practical materials, like the ones in batteries – to study the charging and discharging process and see how the structure of the battery changes, for instance. The second is to understand the fundamental underlying physics principles that govern the behavior of materials.”

    Eventually, she added, theorists want to understand those physics principles so well that they can predict the results of high-priority experiments at facilities that haven’t even been built yet – for instance at LCLS-II, a major upgrade to LCLS that will add a much brighter X-ray laser beam that fires up to a million pulses per second. These predictions have the potential to make experiments at new facilities much more productive and efficient.

    Running Experiments in Supercomputers

    Theoretical work can involve a lot of math and millions of hours of supercomputer time, as theorists struggle to clarify how the fundamental laws of quantum mechanics apply to the materials they are investigating, Pemmaraju says.

    “We use these laws in a form that can be simulated on a computer to make predictions about new materials and their properties,” he says. “The full richness and complexity of the theory are still being discovered, and its equations can only be solved approximately with the aid of supercomputers.”

    Jia adds that you can think of these computer simulations as numerical experiments – working “in silico,” rather than at a lab bench. By simulating what’s going on in a material, scientists can decide which of all the experimental options are the best ones, saving both time and money.

    The institute’s core research team includes theorists Joel Moore of the University of California, Berkeley and John Rehr of the University of Washington. Rehr is the developer of FEFF, an efficient and widely accessible software code that is used by the X-ray light source community worldwide. Devereaux says the plan is to establish a center for FEFF within the institute, which will serve as a home for its further development and for making those advances widely available to theorists and experimentalists at various levels of sophistication.

    TIMES and SIMES are funded by the DOE Office of Science, and the three light sources – ALS, SSRL and LCLS – are DOE Office of Science User Facilities.

    See the full article here .

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  • richardmitnick 6:04 am on December 6, 2016 Permalink | Reply
    Tags: , Inorganic geochemistry, Molecular environmental science, , SLAC Stanford SSRL,   

    From Stanford: “Eureka moment leads to new method of studying environmental toxins” 

    Stanford University Name
    Stanford University

    March 31, 2016 [Stanford just saw fit to put this in social media.]
    Ker Than

    1
    View of the TVA Kingston Fossil Plant fly ash spill. Work using X-ray beams is clarifying how pollutants bind or release from solid surfaces and move into groundwater. Photo: Brian Stansberry via Wikimedia Commons

    A technique for probing the surface of particles revealed how toxins move from the soil to groundwater.

    In 1986, Gordon Brown used SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL) to visualize something no one had ever seen before: the exact way that atoms bond to a solid surface.

    SLAC/SSRL
    SLAC/SSRL

    The work stemmed from a eureka moment that Brown had during the doctoral defense of graduate student Kim Hayes but has since grown into one of the seminal works in inorganic geochemistry, and even spawned a new field of study — molecular environmental science.

    Knowing how charged ions interact with solid surfaces is crucial for understanding how toxic metal ions such as lead, arsenic and mercury or radioactive elements such as uranium may be released from particles in soils and sediments and into groundwater or vice versa. Using the techniques Brown’s team helped pioneer, scientists today can paint exquisitely detailed pictures of how metal ions bind to different solid surfaces, including those on nanoparticles.

    “You can determine what other atoms are around the pollutant ions of interest, the inter-atomic distances separating them and the number and types of chemical bonds that keep them bound to the surface,” says Brown, a professor of geological sciences and of photon science. “This is crucial for understanding how easily they move from one place to another.”


    Access mp4 video here .

    Synchrotron-generated X-rays like those produced at SSRL are ideal for this type of investigation for a number of reasons, says John Bargar, a senior scientist at SLAC and Brown’s former PhD student. For one thing, synchrotron X-rays are highly focused, much like laser beams. “All of the photons produced are condensed into either a pencil beam or a narrow fan,” Bargar says. “That means you can use nearly all of the photons that you’re making with very little waste.”

    Another advantage of synchrotron X-rays, Brown says, is that their extremely high intensity makes it possible to detect and study pollutant ions at the very low concentration levels typically found in many polluted environmental samples.

    Moreover, synchrotron X-rays are polarized, meaning their waves vibrate primarily in a single plane. By modifying the direction of polarization, scientists can create very powerful probes for studying chemical bonds in molecules.

    “A metal ion sitting inside a larger molecule is surrounded by many bonds. Oftentimes, we don’t want to interrogate all of those bonds at once,” Bargar says. “With polarized X-rays, we can selectively interrogate the bonds in a specific orientation.”

    Recently, Brown and Bargar have collaborated to study how organic matter and live microbial organisms affect the binding affinities of different environmental pollutants to solid surfaces. Bargar and Brown are also investigating ways to harness bacterial aggregations called biofilms to neutralize the effects of environmental pollutants. In addition, they are also using synchrotron X-rays at SSRL to look for more efficient ways of safely extracting oil and gas from tight shales via hydraulic fracturing, a process that is transforming the energy landscape of the United States.

    “The X-ray beams synchrotrons are able to generate today are about 15 orders of magnitude brighter than what was available when I was a graduate student. This has led to a revolution in all areas of science and engineering,” Brown says. “I could collect the data for my entire PhD thesis in one morning at SSRL now.”

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 12:44 pm on August 5, 2013 Permalink | Reply
    Tags: , , , , , SLAC Stanford SSRL,   

    From Stanford: “Disorder can improve the performance of plastic solar cells, Stanford scientists say” 

    Stanford University Name
    Stanford University

    Instead of mimicking rigid solar cells made of silicon crystals, scientists should embrace the inherently disordered nature of plastic polymers, a Stanford study has found

    August 4, 2013
    Mark Shwartz

    “Scientists have spent decades trying to build flexible plastic solar cells efficient enough to compete with conventional cells made of silicon. To boost performance, research groups have tried creating new plastic materials that enhance the flow of electricity through the solar cell. Several groups expected to achieve good results by redesigning pliant polymers of plastic into orderly, silicon-like crystals, but the flow of electricity did not improve.

    Recently, scientists discovered that disorder at the molecular level actually improves the polymers’ performance. Now Stanford University researchers have an explanation for this surprising result. Their findings, published in the Aug. 4 online edition of the journal Nature Materials, could speed up the development of low-cost, commercially available plastic solar cells.

    cell
    These X-ray images reveal the microscopic structure of two semiconducting plastic polymers. The bottom image, with several big crystals stacked in a row, is from a highly ordered polymer sample. The top image shows a disordered polymer with numerous tiny crystals that are barely discernible.

    ‘People used to think that if you made the polymers more like silicon they would perform better,’ said study co-author Alberto Salleo, an associate professor of materials science and engineering at Stanford. ‘But we found that polymers don’t naturally form nice, well-ordered crystals. They form small, disordered ones, and that’s perfectly fine.’

    Instead of trying to mimic the rigid structure of silicon, Salleo and his colleagues recommend that scientists learn to cope with the inherently disordered nature of plastics.”

    X-ray analysis

    To observe the disordered materials at the microscopic level, the Stanford team took samples to the SLAC National Accelerator Laboratory for X-ray analysis. The X-rays revealed a molecular structure resembling a fingerprint gone awry. Some polymers looked like amorphous strands of spaghetti, while others formed tiny crystals just a few molecules long.

    ‘The crystals were so small and disordered you could barely infer their presence from X-rays,’ Salleo said. ‘In fact, scientists had assumed they weren’t there.’

    By analyzing light emissions from electricity flowing through the samples, the Stanford team determined that numerous small crystals were scattered throughout the material and connected by long polymer chains, like beads in a necklace. The small size of the crystals was a crucial factor in improving overall performance, Salleo said.

    Other authors of the study are postdoctoral scholar Koen Vandewal of Stanford; Felix Koch and Paul Smith of ETH Zurich; Natalie Stingelin of Imperial College London; and Michael Toney of the SLAC Stanford Synchrotron Radiation Lightsource.”

    See the full article here.

    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 1:29 pm on July 8, 2013 Permalink | Reply
    Tags: , , , SLAC SPEAR, , SLAC Stanford SSRL   

    From SLAC: “SPEAR-heading X-ray Science for 40 Years” 

    July 8, 2013
    Manuel Gnida

    “Last Saturday marked the 40th anniversary of an historic event: In 1973, a team of research pioneers extracted hard X-rays for the first time from SLAC’s SPEAR accelerator. Like X-rays from an X-ray tube, the radiation generated by SPEAR can deeply penetrate a large variety of materials and probe their inner structures. However, SPEAR’s X-rays are significantly more intense and unlock the possibility for brand new science.

    spear

    Forty years later, SPEAR has matured into SPEAR3 and is running stronger than ever, providing X-rays to SLAC’s Stanford Synchrotron Radiation Lightsource (SSRL). And accelerator-based X-ray research at more than 60 facilities around the world has led to numerous breakthroughs in the materials, life, environmental and other sciences.

    SPEAR was originally built for electron-positron collisions, from which particle physicists gained insights into nature’s fundamental particles and forces. However, it was quickly realized that particle racetracks like SPEAR also produce a byproduct called synchrotron radiation – an intense light with a large spectral range that includes X-rays. Consequently, in 1968, SLAC’s Burton Richter and Wolfgang “Pief” Panofsky granted Stanford University researcher William Spicer’s request to consider the possibility of using SPEAR’s X-rays for experiments, and added a tangential spout to the accelerator’s design as an outlet for this synchrotron radiation.

    ssrl
    Stanford Synchrotron Radiation Project pilot project beamline inside SPEAR, 07/06/1973. (SLAC Archives)

    See the full article here.

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  • richardmitnick 9:10 am on November 28, 2012 Permalink | Reply
    Tags: , , , , , SLAC Stanford SSRL   

    From Brookhaven Lab: “X-rays Illuminate Nitrogen’s Role in Single-layer Graphene” 


    Brookhaven Lab

    Laura Mgrdichian

    “Researchers using x-rays to study a single-atom-thick layer of carbon, called graphene, have learned new information about its atomic bonding and electronic properties when the material is “doped” with nitrogen atoms. They show that synchrotron x-ray techniques can be excellent tools to study and better understand the behavior of doped graphene, which is being eyed for use as a promising contact material in electronic devices due to its many desirable traits, including a high conductivity and, most notably, tunable electronic properties.

    gr
    Graphene is an atomic-scale honeycomb lattice made of carbon atoms. (Wikipedia)

    In this work, the researchers discovered that several bond types may be present between carbon and nitrogen atoms, even within the same graphene sheet. This results in profoundly different effects on the charge carrier concentration across the sheet, which is not ideal.

    The paper’s co-authors include colleagues at Columbia University as well as the Stanford Synchrotron Radiation Lightsource (SSRL), CNR-Nanoscience Institute (Italy), Sejong University (Korea), the National Institute of Standards and Technology, Stockholm University (Sweden), and Brookhaven National Laboratory [Brookhaven NSLS is referenced.].

    See the full article here.

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 11:22 am on November 20, 2012 Permalink | Reply
    Tags: , , , SLAC Stanford SSRL,   

    From SLAC Lab: “SSRL Users Have It Made in the Shade” 

    November 20, 2012
    Lori Ann White

    “Two major multi-year projects reached successful conclusions during the annual shutdown of the Stanford Synchrotron Radiation Lightsource. The projects, a wrapping of insulation over the SPEAR3 tunnel and the installation of new hardware and software at several beamlines, promise to provide many users with steadier X-ray beams that are easier to control.

    image
    The new detector installed at Beam Line 11-2 is constructed from a single piece of germanium. (Photo by Matt Beardsley)

    ‘SSRL has once more completed a busy shutdown with a range of important projects, focusing on improvements and new capabilities, making us ready to provide our user community enhanced capabilities for their research,’ said interim SSRL director Piero Pianetta.

    The insulation around the SPEAR3 storage ring, where circling electrons generate the X-rays that power scientific discoveries at SSRL’s many beamlines, is a cost-effective solution to an issue that has dogged the ring for several years. ‘It prevents temperature differences across the concrete blocks that make up the ring,’ said John Schmerge, head of the SPEAR3 accelerator division. In previous years such temperature differences would cause the floor of the ring to rise tens of microns, lifting the electron beam and ultimately throwing the X-rays off their targets in the experimental hutches.

    Had one part of the structure moved with respect to another, the differences could have given Schmerge’s team clues as to the source of the shift. But when the floor moved, the entire accelerator moved with it in concert. ‘The electron sensors said the beam wasn’t moving,’ even though the X-ray detectors along the experimental floor disagreed, Schmerge said. Although feedback mechanisms helped them correct the beam’s wanderings, they wanted to address the motion itself.”

    There is more too this story, read the whole article here.

    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 5:39 pm on October 23, 2012 Permalink | Reply
    Tags: , , , , , , SLAC Stanford SSRL   

    From SLAC Today: “SSRL Yields Clues to Function of Vital Protein Family” 

    October 23, 2012
    Lori Ann White

    “A team of Stanford University researchers used the Stanford Synchrotron Radiation Lightsource. to gain a deeper understanding of a vital family of signaling proteins responsible for regulating an organism’s development and growth, as well as tissue regeneration and wound healing. The protein family, known by the collective name ‘Wnt,’ can cause havoc when their signals go astray; mistakes in Wnt signaling are associated with the development of many types of cancer, including colon cancer, breast cancer and melanoma, and degenerative diseases like multiple sclerosis, Alzheimer’s and type 2 diabetes.

    graph
    Overview of signal transduction pathways. On the upper right hand side of the cell, a Wnt signaling protein is shown to bind to a frizzled receptor. Wikipedia

    protein
    XWnt8, a member of the family of signaling proteins called “Wnt” proteins, has an unusual structure resembling a fist with an outstretched thumb and index finger. No image credit.

    See the full article here.

    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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