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  • richardmitnick 1:57 pm on January 24, 2014 Permalink | Reply
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    From Argonne APS: “Earth’s Core Reveals an Inner Weakness” 

    News from Argonne National Laboratory

    JANUARY 23, 2014
    Michael Schirber

    The word “core” conjures up an image of something strong. However, new experiments show that the iron found in the Earth’s core is relatively weak. This finding is based on x-ray spectroscopy and diffraction measurements performed at high pressure and utilizing several x-ray beamlines at two U.S. Department of Energy Office of Science light sources including the Advanced Photon Source at Argonne National Laboratory. The researchers in these studies extrapolated their results to core conditions and found that the strength of iron deep within the Earth is lower than previously thought. This weakness may explain how the crystal structure in the Earth’s core has transformed over geological time scales.

    graph
    The strength of several different metals, extrapolated to high pressure. (Courtesy of A.E. Gleason.)

    The extreme conditions of the Earth’s core are very difficult to reproduce in a laboratory. The pressure rises above 3 million atmospheres (atm, 320-370 gigapascals, or GPa), and the temperature is comparable to that on the surface of the Sun (over 5000° C). Seismologists have learned about the core by studying seismic waves that travel through the Earth’s interior.

    One surprising discovery is that core-traversing seismic waves travel 3% faster along the polar axis as compared to those moving through the equatorial plane. Researchers assume that this seismic-wave anisotropy is due to iron crystals aligning their lattice structures. Such alignment requires a certain amount of “flow” through the solid core, and this has yet to be explained.

    Deep inside the Earth, iron has a different structure than it does at the surface. For objects like horseshoes and tea kettles, the iron atoms are packed together in a pattern called body-centered cubic (bcc). However, when the pressure rises above 12 GPa, the iron atoms rearrange into a hexagonally close-packed (hcp) structure.

    In order to better understand hcp iron, researchers from <a href="Stanford University“>Stanford University and the SLAC National Accelerator Laboratory have made new strength measurements at high pressure, as described in Nature Geoscience. Strength, which is a material’s resistance to flow, is characterized by the pressure at which the material begins to deform. Previous studies of iron’s strength have typically applied pressure in a non-uniform (or non-hydrostatic) way.

    To reproduce the hydrostatic conditions of the Earth’s interior, the researchers here loaded their foil-shaped samples of iron into a gasket filled with a pressure-transmitting medium of neon or helium gas. This gasket was then placed in a diamond-anvil cell, where pressures as high as 200 GPa could be applied.

    To study the material properties of hydrostatically compressed iron, the team first performed nuclear resonant inelastic x-ray scattering (NRIXS) experiments at two Advanced Photon Source x-ray beamlines: 3-ID-B (operated by the Argonne X-ray Science Division within the APS) and16-ID-D (operated by the High Pressure Collaborative Access Team, or HP-CAT). The spectrum of the scattered x-rays contained information about shear waves that travel through the iron like seismic waves. From their data analysis, the team derived the shear modulus — a measure of the rigidity of a material — and found it to be slightly lower than previous measurements of iron taken in non-hydrostatic environments.

    The team then performed radial x-ray diffraction (rXRD) experiments at the HP-CAT 16-BM-D beamline, as well as with another x-ray beamline at the Advanced Light Source at Lawrence Berkeley National Laboratory. These measurements showed a shift in iron diffraction lines due to a squeezing (or strain) of the lattice separation when the sample was under pressure.

    The researchers combined the observed strain and shear modulus values to obtain the strength of iron at high pressures. Surprisingly, the derived strength was 60% lower than previous estimates, making iron one of the weakest metals at high pressures (see the figure).

    The team estimated that iron’s strength is around 1 GPa at the pressure and temperature of the Earth’s core. This low value has implications for how the material in the core deforms, or “creeps,” over time. Previous models assumed that this creep was a very slow process, based mostly on diffusion of atoms. However, a lower strength for iron means that creep could occur through the movement of defects, or “dislocations,” in the crystal structure. This faster dislocation creep would imply that the observed seismic-wave anisotropy developed relatively early in the Earth’s history.

    To explore this idea further, the team plans to perform a new set of iron experiments at high temperature as well as high pressure.

    See the full article here.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security.

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  • richardmitnick 11:46 am on June 14, 2013 Permalink | Reply
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    From Argonne Lab: “Discovery of new material state counterintuitive to laws of physics” 

    Argonne National Laboratory

    June 11, 2013
    Tona Kunz

    ” When you squeeze something, it gets smaller. Unless you’re at Argonne National Laboratory. At the suburban Chicago laboratory, a group of scientists has seemingly defied the laws of physics and found a way to apply pressure to make a material expand instead of compress/contract. “It’s like squeezing a stone and forming a giant sponge,” said Karena Chapman, a chemist at the U.S. Department of Energy laboratory. “Materials are supposed to become denser and more compact under pressure. We are seeing the exact opposite. The pressure-treated material has half the density of the original state. This is counterintuitive to the laws of physics.” Because this behavior seems impossible, Chapman and her colleagues spent several years testing and retesting the material until they believed the unbelievable and understood how the impossible could be possible. For every experiment, they got the same mind-bending results.

    mat
    Pressure-induced transitions are associated with near 2-fold volume expansions. While an increase in volume with pressure is counterintuitive, the resulting new phases contain large fluid-filled pores, such that the combined solid + fluid volume is reduced and the inefficiencies in space filling by the interpenetrated parent phase are eliminated.

    The scientists put zinc cyanide, a material used in electroplating, in a diamond-anvil cell at the Advanced Photon Source (APS) at Argonne and applied high pressures of 0.9 to 1.8 gigapascals, or about 9,000 to 18,000 times the pressure of the atmosphere at sea level. This high pressure is within the range affordably reproducible by industry for bulk storage systems. By using different fluids around the material as it was squeezed, the scientists were able to create five new phases of material, two of which retained their new porous ability at normal pressure. The type of fluid used determined the shape of the sponge-like pores. This is the first time that hydrostatic pressure has been able to make dense materials with interpenetrated atomic frameworks into novel porous materials. Several series of in situ high-pressure X-ray powder diffraction experiments were performed at the 1-BM, 11-ID-B, and 17-BM beamlines of the APS to study the material transitions.

    Argonne APS
    Advanced Photon Source

    See the full article here.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science


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  • richardmitnick 11:47 am on May 21, 2013 Permalink | Reply
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    From Argonne APS: “Nanocrystals Grow from Liquid Interface” 

    Argonne National Laboratory

    MAY 20, 2013

    “Liquid interface behavior cannot be investigated at atomic level by most modern methods. Only brilliant X-rays at world-leading light sources can investigate this type of important chemical processes.

    mix
    Illustration of the nano-layer at the liquid interface between the salt solution and mercury. Physicists from Kiel University discovered the formation of an ordered crystal of exactly five atomic layers between the two liquids with brilliant X-rays. Image courtesy Christian-Albrechts-Universität zu Kiel.

    The result is reported on in the April issue of the journal Proceedings of the National Academy of Science in an article titled In situ x-ray studies of adlayer-induced crystal nucleation at the liquid-liquid interface.

    The team used high-energy, high-brilliance X-rays at the LSS (liquid surface spectrometer) at the 9-ID-C beamline of the U.S. Department of Energy Office of Science’s Advanced Photon Source at Argonne National Laboratory and the LISA diffractometer (Liquid Interfaces Scattering Apparatus) at the PETRA III light source at the German laboratory DESY. The research is the continuation and expansion of research done at the APS in 2010.

    In their latest work, the researchers from the U.S., Israel and Germany wanted to find out, for the first time, what exactly occurs during chemical growth at liquid interfaces. Led by researchers from the Institute of Experimental and Applied Physics of Kiel University, the team observed the formation of an ordered crystal of exactly five atomic layers between the two liquids, which acts as a foundation for growing even bigger crystals. This work may result in new semiconductor and nanoparticle production processes.”

    See the full article here.

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  • richardmitnick 5:40 am on April 13, 2013 Permalink | Reply
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    From Argonne APS: “High-pressure imaging breakthrough a boon for nanotechnology” 

    News from Argonne National Laboratory

    APRIL 9, 2013
    Tona Kunz

    “The study of nanoscale material just got much easier, and the design of nanoscale technology could get much more efficient, thanks to an advance in X-ray analysis.

    Nanomaterials develop new physical and chemical properties, such as superconductivity and enhanced strength, when exposed to extreme pressure. A better understanding of how and when those changes occur can guide the design of better products that use nanotechnology.

    But high-energy X-rays produced by lightsources such as the Advanced Photon Source (APS) at Argonne National Laboratory are the only way to study the in-situ structural changes induced by pressure in nanomaterials, and those studies have lacked precision.

    Until now.

    spots
    Bragg CXDI measurements were performed at 0.8, 1.7, 2.5, 3.2, and 6.4 GPa on the same crystal. The reconstructed images (both top and bottom views) are shown above. From W. Yang et al., Nat. Comm. 4 (2013).

    As reported in a Carnegie Institute of Science press release, an international team of scientists using the APS detailed in the April 9 issue of the journal Nature Communications that they devised a way to overcome the distortion caused by sample environments used with the X-rays to improve spatial resolution imaging by two orders of magnitude. This 30-nanometer resolution greatly reduces uncertainties for studies of nanoscale materials. Researchers expect to fine-tune the technique to reach resolutions of a few nanometers in subsequent experiments.

    The team, with members from the Carnegie Institution of Washington, the Center for High Pressure Science and Technology Advanced Research (P.R. China), Argonne National Laboratory, University College London (UK), and the Research Complex at Harwell (UK), found that by averaging the patterns of the bent waves—the diffraction patterns—of the same crystal using different sample alignments in the instrumentation, and by using an algorithm developed by researchers at the London Centre for Nanotechnology, they could compensate for the distortion and improve spatial resolution by two orders of magnitude. The new technique is called the “mutual coherent function” method, or MCF.”

    See the Argonne article here. See the Argonne APS article here.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security.

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  • richardmitnick 5:25 pm on April 10, 2013 Permalink | Reply
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    From Argonne APS: "Protein Structure Could Lead to Better Treatments for HIV, Early Aging" 

    News from Argonne National Laboratory

    APRIL 9, 2013
    No Writer Credit

    “Researchers have determined the molecular structure of a protein whose mutations have been linked to several early aging diseases, and side effects for common human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS) medications. This breakthrough could eventually help researchers develop new treatments for these early-aging diseases and redesign AIDS medications to avoid side effects such as diabetes. The research was carried out at the Southeastern Regional Collaborative Access Team(SER-CAT) facility at the U.S. Department of Energy Office of Science’s Advanced Photon Source (APS) at Argonne National Laboratory.

    ribbon
    Ribbon diagram of the Ste24p protease.

    The researchers from the University of Virginia School of Medicine, the Hauptman-Woodward Medical Research Institute, and the University of Rochester School of Medicine and Dentistry determined the molecular structure of the enzyme Ste24p. Their Membrane Protein Structural Biology Consortium is funded by the National Institutes of Health Protein Structure Initiative, which supports the determination of molecular structures of biomedically important target proteins. Their findings were published March 29 in the journal Science.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security.

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  • richardmitnick 6:49 pm on April 5, 2013 Permalink | Reply
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    From Argonne APS: “Antibody evolution could guide HIV vaccine development” 

    News from Argonne National Laboratory

    “Observing the evolution of a particular type of antibody in an infected HIV-1 patient has provided insights that will enable vaccination strategies that mimic the actual antibody development within the body. Spearheaded by Duke University, the multi-institution study included analysis from Los Alamos National Laboratory and used high-energy X-rays from the Advanced Photon Source at Argonne National Laboratory.

    weeks
    The evolution of the viral protein (green) from 14 weeks through 100 weeks post-transmission is compared with the maturation of the human antibody.

    The kind of antibody studied is called a broadly cross-reactive neutralizing antibody, and details of its generation could provide a blueprint for effective vaccination, according to the study’s authors. In a paper published online in Nature this week titled Co-evolution of a broadly neutralizing HIV-1 antibody and founder virus, the team reported on the isolation, evolution and structure of a broadly neutralizing antibody from an African donor followed from the time of infection.

    The observations trace the co-evolution of the virus and antibodies, ultimately leading to the development of a strain of the potent antibodies in this subject, and they could provide insights into strategies to elicit similar antibodies by vaccination.

    Patients early in HIV-1 infection have primarily a single “founder” form of the virus that has been strong enough to infect the patient, even though the population in the originating patient is usually far more diverse and contains a wide variety of HIV mutations. Once the founder virus is involved in the new patient’s system, the surrounding environment stimulates the HIV to mutate and form a unique, tailored population of virus that is specific to the individual.

    ‘Our hope is that a vaccine based on the series of HIV variants that evolved within this subject, that were together capable of stimulating this potent broad antibody response in his natural infection, may enable triggering similar protective antibody responses in vaccines,’ said [Bette] Korber, leader of the Los Alamos team.”

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security.

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  • richardmitnick 11:42 am on March 13, 2013 Permalink | Reply
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    From Argonne: “Teasing Out the Nature of Structural Instabilities in Ceramic Compounds” 

    News from Argonne National Laboratory

    MARCH 12, 2013
    No Writer Credit

    “Materials scientists have been for some time preparing artificial ceramic systems that simply do not exist in nature, allowing scientists to engineer particularly interesting and even technologically applicable behaviors. But sometimes nature itself finds ingenious solutions to physical problems that we have not been able to solve.

    image
    The simple perovskite structure of EuTiO3 illustrated above shows the essential competing structural instabilities. At the center of the figure is the oxygen cage rotation, and to the right is the central titanium displacement. X-ray diffraction studies showed that, to accommodate the incompatibility of these distortions, they naturally form a long, inter-digitized superstructure (illustrated at far left), which allows them to coexist. Ultimately, this research demonstrates that when both electric and magnetic fields are applied as the europium spins align, the oxygen cage responds, mediating communication between the titanium electric and europium magnetic parameters.

    An international team of researchers lead by Argonne National Laboratory utilized high-brightness x-rays from the U.S. Department of Energy Office of Science’s Advanced Photon Source at Argonne National Laboratory, as well as the European Synchrotron Radiation Facility (ESRF), to study the rare-earth magnetic material europium titanate (EuTiO3). Their results were published in the journal Physical Review Letters.

    In a magnetic field, the (near) optical properties of EuTiO3 change quite dramatically, presenting hope of a strong magneto-electric material often dreamed of by engineers for use in combining magnetic and charge parameters for many memory, processing, and sensor devices.

    Emerging ceramic materials are displaying a tantalizing array of characteristics that could find application in existing and new technologies including magnetic, piezoelectric, ferroelectric, metal insulator transitions, and even superconductivity. Most interesting to physicists is the delicate nature balancing the underlying parameters that drive each quality. If one introduces a different mix of materials, perhaps replacing one element with another or even slightly distorting the structure, then one parameter disappears while another emerges. How all the separate electronic orbits behave and interact with respect to, and with, each other is a fascinating arena for scientists seeking to understand ceramics, a well-known and ancient material family.”

    See the full article here.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

    The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security.

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  • richardmitnick 6:12 pm on February 10, 2013 Permalink | Reply
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    From Argonne Lab: “New classes of magnetoelectric materials promise advances in computing technology” 

    News from Argonne National Laboratory

    February 7, 2013
    Jared Sagoff

    Although scientists have been aware that magnetism and electricity are two sides of the same proverbial coin for almost 150 years, researchers are still trying to find new ways to use a material’s electric behavior to influence its magnetic behavior, or vice versa.

    star
    An illustration of a titanium-europium oxide cage lattice studied in the experiment.Image by Renee Carlson.

    Thanks to new research by an international team of researchers led by the U.S. Department of Energy’s Argonne National Laboratory, physicists have developed new methods for controlling magnetic order in a particular class of materials known as “magnetoelectrics.”

    Magnetoelectrics get their name from the fact that their magnetic and electric properties are coupled to each other. Because this physical link potentially allows control of their magnetic behavior with an electrical signal or vice versa, scientists have taken a special interest in magnetoelectric materials.

    ‘Electricity and magnetism are intrinsically coupled – they’re the same entity,’ said Philip Ryan, a physicist at Argonne’s Advanced Photon Source. ‘Our research is designed to accentuate the coupling between the electric and magnetic parameters by subtly altering the structure of the material.

    This new approach to cross-coupling magnetoelectricity could prove a key step toward the development of next-generation memory storage, improved magnetic field sensors, and many other applications long dreamed about. Unfortunately, scientists still have a ways to go to translating these findings into commercial devices.’

    ‘Instead of having just a ‘0’ or a ‘1,’ you could have a broader range of different values,’ Ryan said. ‘A lot of people are looking into what that kind of logic would look like.’

    A paper based on the research, “Reversible control of magnetic interactions by electric field in a single-phase material,” was published in Nature Communications. “

    See the full article here.

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  • richardmitnick 1:20 pm on February 9, 2013 Permalink | Reply
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    From Argonne Lab: “The Electronic Origin of Photoinduced Strain” 

    News from Argonne National Laboratory

    FEBRUARY 8, 2013

    Faster data storage devices with lower power consumption can result from optical control of electronic and structural properties. This understanding of how that light can induce simultaneous structural and electronic effects now enables optical control of ferroelectric and multiferroic materials without requiring electrical contacts.

    Multiferroics are in a class of materials that exhibits more than one ferroic order simultaneously. One of the prototypical multiferroics is BiFeO3, an important material because it is one of a few materials that exhibit both ferroelectricity and magnetism at room temperature. The interaction of BiFeO3 with light has attracted great attention because optical control of either magnetism, ferroelectricity, or both has implications for future electronic devices.

    diagram
    The dynamics of the lattice structure of a BiFeO3 thin film upon optical excitation was measured with the atomic accuracy by a time-resolved x-ray diffraction probe.

    Now, a team of researchers led by Argonne scientists at the Advanced Photon Source (APS) and Center for Nanoscale Materials (CNM), along with colleagues from the University of Wisconsin-Madison, Cornell University, Northwestern University, Sandia National Laboratories, and Kavli Institute at Cornell for Nanoscale Science, has revealed the electronic origin of the interaction between optical light using a nanometer-thick layer of BFO at the atomic level and ultrafast time scales. Their work was recently published in Physical Review Letters.

    See the full article here.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

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  • richardmitnick 1:01 pm on February 9, 2013 Permalink | Reply
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    From Argonne Lab : “Ultrafast X-Ray Spectroscopy as a Probe of Nonequilibrium Dynamics in Ruthenium Complexes” 

    News from Argonne National Laboratory

    FEBRUARY 8, 2013
    No Writer Credit

    “Exciting the atoms or molecules of a substance via the use of visible light, or photoexcitation, can play a significant role in a range of energy-conversion processes, such as natural photosynthesis (oxygen from water) and manmade solar cells (electricity from sunlight).

    laser
    Photons emitted in a coherent beam from a laser

    But a better understanding of the photoexcitation process is necessary in order to fully exploit this potential resource. Researchers from Argonne National Laboratory and Northern Illinois University have shown that the ultrafast x-ray spectroscopy technique employed at a high-brightness x-ray light source such as the Argonne Advanced Photon Source can produce valuable new information about the physics underlying photoexcitation.

    Typical examples of photoinduced phenomena are insulator-to-metal transitions, magnetization and demagnetization, spin-crossover transitions, and melting of charge and orbital order. The typical timescale of the dynamics is of the order of picoseconds (1/1,000,000,000,000 of a second) down to femtoseconds (1/1,000,000,000,000,000 of a second).

    See the full article here.

    Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science

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