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  • richardmitnick 8:27 am on July 12, 2019 Permalink | Reply
    Tags: , , , dDAC-dynamic diamond anvil cell, DESY Petra III, , ,   

    From Lawrence Livermore National Laboratory: “Under pressure: New device’s 1.6 billion atmospheres per second assists impact studies” 

    From Lawrence Livermore National Laboratory

    July 11, 2019

    Anne M Stark
    stark8@llnl.gov
    925-422-9799

    1
    The new dynamic diamond anvil cell (dDAC) at the Extreme Conditions Beamline (ECB) at DESY’s X-ray source PETRA III. Image courtesy of Hanns-Peter Liermann/DESY

    A new super-fast high-pressure device at DESY’s PETRA III X-ray light source allows scientists to simulate and study earthquakes and meteorite impacts more realistically in the lab.

    DESY Petra III

    The new-generation dynamic diamond anvil cell (dDAC), developed by scientists from Lawrence Livermore National Laboratory (LLNL), Deutsches Elektronen-Synchroton (DESY), the European Synchrotron Radiation Facility (ESRF) and the universities of Oxford, Bayreuth and Frankfurt/Main, compresses samples faster than any similar device before. The instrument can turn up the pressure at a record rate of 1.6 billion atmospheres per second and can be used for a wide range of dynamic high-pressure studies. The developers present their new device, that has already proved its capabilities in various materials experiments, in the journal Review of Scientific Instruments.

    “For more than half a century, the diamond anvil cell or DAC has been the primary tool to create static high pressures to study the physics and chemistry of materials under those extreme conditions — for example, to explore the physical properties of materials at the center of the Earth at 3.5 million atmospheres,” said lead author Zsolt Jenei from LLNL.

    To simulate fast dynamic processes like earthquakes and asteroid impacts more realistically with high compression rates in the lab, Jenei’s team, in collaboration with DESY scientists, developed a new generation of dynamically driven diamond anvil cell (dDAC), inspired by the pioneering original LLNL design, and coupled it with the new fast X-ray diffraction setup of the Extreme Conditions Beamline P02.2 at PETRA III.

    The new cell consists of two small modified brilliant diamonds that are pushed together by a powerful piezo electric drive. Thanks to improvements like the much stronger piezo actuators and fast, high peak current amplifiers, the new device is capable of rapidly compressing the tiny samples between the diamond anvils more than a thousand times faster than previous generation dynamic diamond anvil cells. “One unique aspect fo the dDAC technique is that it also allows us to characterize the response of a sample under well controlled fast decompression,” said co-author Earl O’Bannon from LLNL.

    To study the changes in physical properties of materials under high pressure, scientists shine X-rays on the small samples and record the way the X-rays are diffracted by the material. These diffraction patterns allow scientists to determine the structure of the material. However, to take snapshots of high-speed dynamic processes, the X-ray flash needs to be bright enough and the camera — the detector — must be fast enough.

    “For almost 10 years since the first invention of the dDAC at our Laboratory, it has been extremely difficult to conduct fast diffraction experiments because of the lack of photon flux and, more important, fast and highly sensitive high-energy X-ray diffraction detectors,” Jenei said. Only with the advent of the extremely bright third-generation X-ray sources, such as PETRA III, and the development of highly sensitive cameras, such as the gallium-arsenide (GaAs) Lambda detector, invented by the DESY detector group, did it become possible to collect diffraction images with the adequate short exposure times and temporal resolution.”

    The Extreme Conditions Beamline (ECB) at DESY has the world’s first two GaAs Lambda detectors. “By triggering them with a delay of 0.25 milliseconds, we are able to collect up to 4,000 frames per second,” said Hanns-Peter Liermann, the beamline scientist in charge of the ECB. The detectors were funded through a joint research project awarded by the German Federal Ministry of Education and Research BMBF to the Goethe University Frankfurt, where Björn Winkler is the principal investigator.

    Researchers working on the project have demonstrated the performance and versatility of the experimental setup with fast compression studies of heavy metals such as gold and bismuth, as well as light compounds such as ice (H2O) and planetary materials such as ferropericlase. While conducting fast diffraction experiments on gold, the team demonstrated an increase in pressure from 1,000 atmospheres to 1.4 million atmospheres in only 2.5 milliseconds (thousandth of a second), resulting in a maximum compression rate of 160 terapascals per second (a terapascal is a measure of pressure). During this extremely short time, the detectors collected eight diffraction patterns across the complete compression path.

    “We believe that with the existing setup we can improve the compression rates to maybe thousands of terapascals per second,” Liermann said. However, this will need even brighter X-ray flashes and still faster cameras such as the planned upgrade of PETRA III to a next-generation X-ray source PETRA IV and the High Energy Density experimental station (HED) at the European X-ray laser European XFEL, where DESY is participating in building a dDAC setup as part of the Helmholtz International Beamline for Extreme Fields (HIBEF) consortium.

    See the full article here .


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    LLNL Campus

    Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security Administration
    Lawrence Livermore National Laboratory (LLNL) is an American federal research facility in Livermore, California, United States, founded by the University of California, Berkeley in 1952. A Federally Funded Research and Development Center (FFRDC), it is primarily funded by the U.S. Department of Energy (DOE) and managed and operated by Lawrence Livermore National Security, LLC (LLNS), a partnership of the University of California, Bechtel, BWX Technologies, AECOM, and Battelle Memorial Institute in affiliation with the Texas A&M University System. In 2012, the laboratory had the synthetic chemical element livermorium named after it.
    LLNL is self-described as “a premier research and development institution for science and technology applied to national security.” Its principal responsibility is ensuring the safety, security and reliability of the nation’s nuclear weapons through the application of advanced science, engineering and technology. The Laboratory also applies its special expertise and multidisciplinary capabilities to preventing the proliferation and use of weapons of mass destruction, bolstering homeland security and solving other nationally important problems, including energy and environmental security, basic science and economic competitiveness.

    The Laboratory is located on a one-square-mile (2.6 km2) site at the eastern edge of Livermore. It also operates a 7,000 acres (28 km2) remote experimental test site, called Site 300, situated about 15 miles (24 km) southeast of the main lab site. LLNL has an annual budget of about $1.5 billion and a staff of roughly 5,800 employees.

    LLNL was established in 1952 as the University of California Radiation Laboratory at Livermore, an offshoot of the existing UC Radiation Laboratory at Berkeley. It was intended to spur innovation and provide competition to the nuclear weapon design laboratory at Los Alamos in New Mexico, home of the Manhattan Project that developed the first atomic weapons. Edward Teller and Ernest Lawrence,[2] director of the Radiation Laboratory at Berkeley, are regarded as the co-founders of the Livermore facility.

    The new laboratory was sited at a former naval air station of World War II. It was already home to several UC Radiation Laboratory projects that were too large for its location in the Berkeley Hills above the UC campus, including one of the first experiments in the magnetic approach to confined thermonuclear reactions (i.e. fusion). About half an hour southeast of Berkeley, the Livermore site provided much greater security for classified projects than an urban university campus.

    Lawrence tapped 32-year-old Herbert York, a former graduate student of his, to run Livermore. Under York, the Lab had four main programs: Project Sherwood (the magnetic-fusion program), Project Whitney (the weapons-design program), diagnostic weapon experiments (both for the Los Alamos and Livermore laboratories), and a basic physics program. York and the new lab embraced the Lawrence “big science” approach, tackling challenging projects with physicists, chemists, engineers, and computational scientists working together in multidisciplinary teams. Lawrence died in August 1958 and shortly after, the university’s board of regents named both laboratories for him, as the Lawrence Radiation Laboratory.

    Historically, the Berkeley and Livermore laboratories have had very close relationships on research projects, business operations, and staff. The Livermore Lab was established initially as a branch of the Berkeley laboratory. The Livermore lab was not officially severed administratively from the Berkeley lab until 1971. To this day, in official planning documents and records, Lawrence Berkeley National Laboratory is designated as Site 100, Lawrence Livermore National Lab as Site 200, and LLNL’s remote test location as Site 300.[3]

    The laboratory was renamed Lawrence Livermore Laboratory (LLL) in 1971. On October 1, 2007 LLNS assumed management of LLNL from the University of California, which had exclusively managed and operated the Laboratory since its inception 55 years before. The laboratory was honored in 2012 by having the synthetic chemical element livermorium named after it. The LLNS takeover of the laboratory has been controversial. In May 2013, an Alameda County jury awarded over $2.7 million to five former laboratory employees who were among 430 employees LLNS laid off during 2008.[4] The jury found that LLNS breached a contractual obligation to terminate the employees only for “reasonable cause.”[5] The five plaintiffs also have pending age discrimination claims against LLNS, which will be heard by a different jury in a separate trial.[6] There are 125 co-plaintiffs awaiting trial on similar claims against LLNS.[7] The May 2008 layoff was the first layoff at the laboratory in nearly 40 years.[6]

    On March 14, 2011, the City of Livermore officially expanded the city’s boundaries to annex LLNL and move it within the city limits. The unanimous vote by the Livermore city council expanded Livermore’s southeastern boundaries to cover 15 land parcels covering 1,057 acres (4.28 km2) that comprise the LLNL site. The site was formerly an unincorporated area of Alameda County. The LLNL campus continues to be owned by the federal government.

    LLNL/NIF


    DOE Seal
    NNSA

     
  • richardmitnick 10:37 am on June 28, 2018 Permalink | Reply
    Tags: , , , DESY Petra III, Phase contrast tomography, The human cerebellum   

    From DESY: “Google Maps for the cerebellum” 

    DESY
    From DESY

    Scientists image millions of nerve cells with the help of PETRA III [Image is below].

    2018/06/28

    1
    Result of the phase contrast X-ray tomography at DESY’s X-ray source PETRA III. Credit: Töpperiwen et al., Universität Göttingen

    A team of researchers from Göttingen has successfully applied a special variant of X-ray imaging to brain tissue. With the combination of high-resolution measurements at DESY’s X-ray light source PETRA III and data from a laboratory X-ray source, Tim Salditt’s group from the Institute of X-ray Physics at the Georg August University of Göttingen was able to visualize about 1.8 million nerve cells in the cerebellar cortex. The researchers describe the investigations with the so-called phase contrast tomography in the Proceedings of the National Academy of Sciences (PNAS).

    The human cerebellum contains about 80 percent of all nerve cells in 10 percent of the brain volume – one cubic millimeter can therefore contain more than one million nerve cells. These process signals that mainly control learned and unconscious movement sequences. However, their exact positions and neighbourhood relationships are largely unknown. “Tomography in the so-called phase contrast mode and subsequent automated image processing enables the cells to be located and displayed in their exact position,” explains Mareike Töpperwien from the Institute of X-ray Physics at the University of Göttingen, lead author of the publication.

    The scientists used a biopsy needle to take cylindrical tissue samples from tissue blocks and investigated them with a special phase contrast tomograph developed by Salditt’s research group. Conventional instruments have the disadvantage that small structures and tissues of low density – as in nerve cells – provide little to no contrast and therefore cannot be imaged. The innovative method of the Göttingen researchers is not based on the absorption of X-rays, but on the altered propagation speed of X-rays. The resulting differences in propagation time become indirectly visible through beam propagation on a free flight path between object and detector.

    “For biological samples, this ‘phase’ contrast is up to 1000 times more intense and is used at PETRA III for imaging structures in the sub-micrometer range,” explains DESY researcher Michael Sprung, head of the P10 measuring station where the investigations took place. One micrometer is a thousandth of a millimeter.

    In order to obtain sharp images, the scientists process the images by computer. They can then reconstruct the three-dimensional electron density of the tissue from the entire tomographic image series. “In the future, we will also use this method to show pathological changes, such as those occurring in neurodegenerative diseases, in three dimensions, for example changes in nerve tissue in diseases such as multiple sclerosis,” explains co-author Christine Stadelmann-Nessler, neuropathologist at Göttingen University Medicine.

    The combination of images of different magnifications enabled the Göttingen team to map the cerebellum over many orders of magnitude. “In the future, we want to be able to zoom even further into interesting brain regions, almost like on Google Maps,” says Salditt.

    See the full article here .


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    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

    DESY Petra III interior


    DESY Petra III

    DESY/FLASH

    H1 detector at DESY HERA ring

    DESY DORIS III

     
  • richardmitnick 8:56 am on April 16, 2018 Permalink | Reply
    Tags: , Attosecond X-ray science, DESY Petra III, , , , , XLEAP X-ray Laser-Enhanced Attosecond Pulse generation   

    From European XFEL: “Entering the realm of attosecond X-ray science” 

    XFEL bloc

    European XFEL

    European XFEL

    2018/04/13

    New methods for producing and characterizing attosecond X-ray pulses.

    1
    Ultrashort X-ray pulses (pink) at the Linac Coherent Light Source ionize neon gas at the center of a ring of detectors. An infrared laser (orange) sweeps the outgoing electrons (blue) across the detectors with circularly polarized light. Scientists read data from the detectors to learn about the time and energy structure of the pulses, information they will need for future experiments. Copyright: Terry Anderson / SLAC National Accelerator Laboratory.

    SLAC/LCLS

    European XFEL produces unfathomably fast X-ray pulses that are already being used by scientists to explore the unchartered territory of the atomic and molecular cosmos. Intense X-ray pulses lasting only a few femtoseconds – or a few millionths of a billionth of a second – are being used to reveal insights into the dynamics of chemical reactions and the atomic structures of biological molecules such as proteins and viruses. And while there is much more to discover in this femtosecond time range, scientists are already looking to take European XFEL to the next time dimension, exploring reactions and dynamics that occur on an even briefer time scale – the attosecond time regime.

    If you leave the shutter of your camera open for too long while photographing a race, the resulting pictures will only be a smear of colour. To capture clear and sharp images of the athletes’ movements you need to make sure the shutter is only open for the shortest time; in fact the best shutter speed to capture a clear snapshot of the runners’ legs frozen in action would be faster than the time the runner needed to move their legs. Good light conditions help too to make sure your photos are sharp and in focus. And so it is as scientists attempt to take snapshots of some of nature’s fastest processes such as the movements of electrons within atoms and molecules. To capture snapshots of these movements in action we need pulses of intense X-rays that reflect the timescale on which these reactions occur – and these reactions can occur even down to the attosecond timescale.

    XLEAP

    Attosecond X-ray science is expected to allow scientists to delve even deeper into ultrafast chemical and molecular processes and the tiniest details of our world than already possible. But how to produce X-ray flashes that are even shorter than the already ultrafast femtosecond flashes? One of the methods currently being explored by scientists is ‘X-ray Laser-Enhanced Attosecond Pulse generation’ (XLEAP). The method, being developed at the SLAC National Accelerator Laboratory in the USA, is expected to be possible with only moderate modifications to the layout of existing FEL facilities. If successful, the usually chaotic time and energy structure of XFEL (X-ray Free-Electron Laser) pulses, consisting of a sequence of many intensity spikes based on the so-called SASE (Self-Amplification by Spontaneous Emission) principle, can be reliably narrowed down to one single, coherent intensity spike of only few hundreds of attoseconds. In a recent review article in the Journal of Optics, European XFEL scientists propose how the XLEAP method might be implemented at the SASE 3 branch of the facility, eventually providing attosecond pulses for experiments.

    2
    European XFEL scientist Markus Ilchen working on the original angle resolving time-of-flight spectrometer at PETRA III, DESY. Copyright: European XFEL

    DESY Petra III


    DESY Petra III interior

    Angular Streaking diagnostics

    While the free-electron laser technology is almost ready to provide attosecond pulses, another hurdle is to actually prove and characterize their existence. Experiments to date at XFEL facilities have often relied on indirect measurements and simulations of X-ray pulses to calibrate results. However, only with detailed information from direct measurements of the exact time and energy structure of each X-ray pulse, can X-ray science enter a new era of time resolved and coherence dependent experiments.

    With this in mind, a novel experimental approach was conceived as part of an international collaboration including scientists from SLAC, Deutsches Elektronen-Synchrotron (DESY), European XFEL, the Technical University of Munich, University of Kassel, University of Gothenburg, University of Bern, University of Colorado, University of the Basque Country in Spain, and Lomonosov Moscow State University in Russia. In a study published in the journal Nature Photonics, the international groupdemonstrated the capability of a so-called ‘angular streaking’ method to characterize the time and energy structure of X-ray spikes. The scientists used the shortest pulses available at the Linac Coherent Light Source (LCLS) at SLAC in the USA for their experiment. Using the new angular streaking diagnostic method, millions of pulses, each of a few femtoseconds in length, were successfully captured and analyzed. “Being able to get the precise information about the energy spectrum, as well as the time and intensity structure of every single X-ray pulse is unprecedented” explains Markus Ilchen from the Small Quantum Systems group at European XFEL, one of the principal investigators of this work. “This is really one of the holy grails of FEL diagnostics” he adds enthusiastically.

    The new angular streaking technique works by using the rotating electrical field of intense circularly polarized optical laser pulses to extract the time and energy structure of the XFEL pulses. Interaction with the XFEL pulse causes atoms to eject electrons which are then strongly kicked around by the surrounding laser field. Information about the electron’s exact time of birth is not only imprinted in the energy of the electron but also in the ejecting angle. This all provides a ‘clock’ by which to sort the resulting experimental data. Pulses generated by the SASE process, as implemented at European XFEL and SLAC, are intrinsically variable and chaotic. Some of the recorded pulses during the experiment at SLAC were, therefore, already single spikes in the attosecond regime which then were fully characterized for their time-energy structure.

    Angle resolving time-of-flight spectrometer

    1
    An illustration of the ring-shaped array of 16 individual detectors arranged in a circle like numbers on the face of a clock. An X-ray laser pulse hits a target at the center and sets free electrons that are swept around the detectors. The location, where the electrons reach the “clock,” reveals details such as the variation of the X-ray energy and intensity as a function of time within the ultrashort pulse itself. Copyright: Frank Scholz & Jens Buck, DESY.

    he underlying spectroscopic method is based on an angle resolving time-of-flight spectrometer setup consisting of 16 individual spectrometers aligned in a plane perpendicular to the XFEL beam. These are used to characterize the X-ray beam by correlating the electrons’ energies and their angle dependent intensities. An adapted version of the spectrometer setup originally developed at the PETRA III storage ring at DESY, was built in the diagnostics group of European XFEL and provided for the beamtime at SLAC.

    At European XFEL the diagnostic goal is that scientists will eventually be able to use the method to extract all information online during their experiments and correlate and adjust their data analysis accordingly. Furthermore, although the method has so far only been designed and tested for soft X-rays, Ilchen and his colleagues are optimistic that it could also be used for experiments using hard X-rays. “By reducing the wavelength of the optical laser, we could even resolve the few hundreds of attosecond broad spikes of the hard X-ray pulses here at the SASE 1 branch of European XFEL” Ilchen says.

    Time-resolved experiments

    During the experiment at SLAC the scientists also showed that it was even possible to use the acquired data to select pulses with exactly two intensity spikes with a variable time delay between them. This demonstrates the capability of FELs to enable time-resolved X-ray measurements attosecond to few femtosecond delay. “By determining the time duration and distance of those two spikes, we can sort our data for matching pulse properties and use them to understand how certain reactions and processes have progressed on an attosecond timescale” explains Ilchen. “Since our method gives us precise information about the pulse structure, we will be able to reliably reconstruct what is happening in our samples by producing a sequence of snapshots, so that much like a series of photographs pasted together makes a moving film sequence, we can make ‘movies’ of the reactions” he adds.

    From principle to proof

    Due to the limited pulse repetition rate currently available at most XFELs, however, moving from a proof-of-principle experiment to actually using specifically structured pulses for so-called pump-probe experiments requires a large leap of the imagination. European XFEL, however, already provides more pulses per second than other similar facilities, and will eventually provide 27,000 pulses per second, making the dream of attosecond time-resolved experiment a real possibility. “Although, currently, no machine in the world can provide attosecond X-ray pulses with variable time delay below the femtosecond regime in a controlled fashion,” says Ilchen, “the technologies available at European XFEL in combination with our method, could enable us to produce so much data that we can pick the pulse structures of interest and sort the rest out while still getting enough statistics for new scientific perspectives.”

    Further reading:

    News from SLAC – “Tick, Tock on the ‘Attoclock’: Tracking X-Ray Laser Pulses at Record Speeds

    Overview of options for generating high-brightness attosecond x-ray pulses at free-electron lasers and applications at the European XFEL
    S. Serkez et al., Journal of Optics, 9 Jan 2018 doi:10.1088/2040-8986/aa9f4f

    See the full article here .

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    XFEL Campus

    XFEL Tunnel

    XFEL Gun

    The Hamburg area will soon boast a research facility of superlatives: The European XFEL will generate ultrashort X-ray flashes—27 000 times per second and with a brilliance that is a billion times higher than that of the best conventional X-ray radiation sources.

    The outstanding characteristics of the facility are unique worldwide. Started in 2017, it will open up completely new research opportunities for scientists and industrial users.

     
  • richardmitnick 1:56 pm on August 17, 2017 Permalink | Reply
    Tags: , DESY Petra III, , , MPG Institute for Nuclear Physics, ,   

    From MPG Institute for Nuclear Physics: “Sharp x-ray pulses from the atomic nucleus” 

    Max Planck Gesellschaft Institute for Nuclear Physics

    August 17, 2017
    PD Dr. Jörg Evers
    Research Group Leader
    Max Planck Institute for Nuclear Physics, Heidelberg
    Phone:+49 6221 516-177
    joerg.evers@mpi-hd.mpg.de

    Prof. Dr. Thomas Pfeifer
    Max Planck Institute for Nuclear Physics, Heidelberg
    Phone:+49 6221 516-380Fax:+49 6221 516-802
    Thomas.Pfeifer@mpi-hd.mpg.de

    Honorary Professor Dr. Christoph H. Keitel
    Max Planck Institute for Nuclear Physics, Heidelberg
    Phone:+49 6221 516-150Fax:+49 6221 516-152
    keitel@mpi-hd.mpg

    Using a mechanical trick, scientists have succeeded in narrowing the spectrum of the pulses emitted by x-ray lasers.

    X-rays make the invisible visible: they permit the way materials are structured to be determined all the way down to the level of individual atoms. In the 1950s it was x-rays which revealed the double-helix structure of DNA. With new x-ray sources, such as the XFEL free-electron laser in Hamburg, it is even possible to “film” chemical reactions.

    XFEL


    XFEL map

    The results obtained from studies using these new x-ray sources may be about to become even more precise. A team around Kilian Heeg from the Max Planck Institute for Nuclear Physics in Heidelberg has now found a way to make the spectrum of the x-ray pulses emitted by these sources even narrower. In contrast to standard lasers, which generate light of a single colour and wavelength, x-ray sources generally produce pulses with a broad spectrum of different wavelengths. Sharper pulses could soon drive applications that were previously not feasible. This includes testing physical constants and measuring lengths and times even more precisely than can be achieved at present.

    1
    Upgrading x-ray lasers – a mechanical trick can be used to narrow the spectrum of the pulses emitted by x-ray lasers such as the XFEL free electron laser shown here. This would enable x-ray lasers to be used for experiments which would otherwise not be possible, for example testing whether physical constants are really constant. © DESY, Hamburg

    Researchers use light and other electromagnetic radiation for developing new materials at work in electronics, automobiles, aircraft or power plants, as well as for studies on biomolecules such as protein function. Electromagnetic radiation is also the tool of choice for observing chemical reactions and physical processes in the micro and nano ranges. Different types of spectroscopy use different individual wavelengths to stimulate characteristic oscillations in specific components of a structure. Which wavelengths interact with the structure – physicists use the term resonance – tells us something about their composition and how they are constructed; for example, how atoms within a molecule are arranged in space.

    In contrast to visible light, which has a much lower energy, x-rays can trigger resonance not just in the electron shell of an atom, but also deep in the atomic core, its nucleus. X-ray spectroscopy therefore provides unique knowledge about materials. In addition, the resonances of some atomic nuclei are very sharp, in principle allowing extremely precise measurements.

    X-ray sources generate ultra-short flashes with a broad spectrum

    Modern x-ray sources such as the XFEL free electron laser in Hamburg and the PETRA III (Hamburg), and ESRF (Grenoble) synchrotron sources are prime candidates for carrying out such studies.

    DESI Petra III

    ESRF. Grenoble, France

    Free- electron lasers in particular are optimized for generating very short x-ray flashes, which are primarily used to study very fast processes in the microscopic world of atoms and molecules. Ultra short light pulses, however, in turn have a broad spectrum of wavelengths. Consequently, only a small fraction of the light is at the right wavelength to cause resonance in the sample. The rest passes straight through the sample, making spectroscopy of sharp resonances rather inefficient.

    It is possible to generate a very sharp x-ray spectrum – i.e. x-rays of a single wavelength – using filters; however, since this involves removing unused wavelengths, the resulting resonance signal is still weak.

    The new method developed by the researchers in Heidelberg delivers a three to four-fold increase in the intensity of the resonance signal. Together with scientists from DESY in Hamburg and ESRF in Grenoble, Kilian Heeg and Jörg Evers from Christoph Keitel’s Division and a team around Thomas Pfeifer at the Max Planck Institute for Nuclear Physics in Heidelberg have succeeded in making some of the x-ray radiation that would not normally interact with the sample contribute to the resonance signal. They have successfully tested their method on iron nuclei both at the ESRF in Grenoble and at the PETRA III synchrotron of DESY in Hamburg.

    A tiny jolt amplifies the radiation

    The researchers’ approach to amplifying the x-rays is based on the fact that, when x-rays interact with iron nuclei (or any other nuclei) to produce resonance, they are re-emitted after a short delay. These re-emitted x-rays then lag exactly half a wavelength behind that part of the radiation which has passed straight through. This means that the peaks of one wave coincide exactly with the troughs of the other wave, with the result that they cancel each other out. This destructive interference attenuates the X-ray pulses at the resonant wavelength, which is also the fundamental origin of absorption of light.

    “We utilize the time window of about 100 nanoseconds before the iron nuclei re-emit the x-rays,” explains project leader Jörg Evers. During this time window, the researchers move the iron foil by about 40 billionths of a millimetre (0.4 angstroms). This tiny jolt has the effect of producing constructive interference between the emitted and transmitted light waves. “It’s as if two rivers, the waves on one of which are offset by half a wavelength from the waves on the other, meet,” says Evers, “and you shift one of the rivers by exactly this distance.” This has the effect that, after the rivers meet, the waves on the two rivers move in time with each other. Wave peaks coincide with wave peaks and the waves amplify, rather than attenuating, each other. This trick, however, does not just work on light at the resonance wavelengths, but also has the reverse effect (i.e. attenuation) on a broader range of wavelengths around the resonance wavelength. Kilian Heeg puts it like this. “We squeeze otherwise unused x-ray radiation into the resonance.”

    To enable the physicists to move the iron foil fast enough and precisely enough, it is mounted on a piezoelectric crystal. This crystal expands or contracts in response to an applied electrical voltage. Using a specially developed computer program, the Heidelberg-based researchers were able to adjust the electrical signal that controls the piezoelectric crystal to maximize the amplification of the resonance signal.

    Applications in length measurement and atomic clocks

    The researchers see a wide range of potential applications for their new technique. According to Thomas Pfeifer, the procedure will expand the utility of new high-power x-ray sources for high-resolution x-ray spectroscopy. This will enable more accurate modelling of what happens in atoms and molecules. Pfeifer also stresses the utility of the technique in metrology, in particular for high-precision measurements of lengths and the quantum-mechanical definition of time. “With x-rays, it is possible to measure lengths 10,000 times more accurately than with visible light,” explains Pfeifer. This can be used to study and optimize nanostructures such as computer chips and newly developed batteries. Pfeifer also envisages x-ray atomic clocks which are far more precise than even the most advanced optical atomic clocks nowadays based on visible light.

    Not least, better X-ray spectroscopy could enable us to answer one of physics’ great unanswered questions – whether physical constants really are constant or whether they change slowly with time. If the latter were true, resonance lines would drift slowly over time. Extremely sharp x-ray spectra would make it possible to determine whether this is the case over a relatively short period.

    Evers reckons that, once mature, the technique would be relatively easy to integrate into experiments at DESY and ESRF. “It should be possible to make a shoe-box sized device that could be rapidly installed and, according to our calculations, could enable an approximately 10-fold amplification,” he adds.

    Science paper:
    Spectral narrowing of x-ray pulses for precision spectroscopy with nuclear resonances
    http://science.sciencemag.org/content/357/6349/375

    See the full article here .

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    The Max-Planck-Institut für Kernphysik (“MPI for Nuclear Physics” or MPIK for short) is a research institute in Heidelberg, Germany.

    The institute is one of the 80 institutes of the Max-Planck-Gesellschaft (Max Planck Society), an independent, non-profit research organization. The Max Planck Institute for Nuclear Physics was founded in 1958 under the leadership of Wolfgang Gentner. Its precursor was the Institute for Physics at the MPI for Medical Research.

    The Max Planck Society is Germany’s most successful research organization. Since its establishment in 1948, no fewer than 18 Nobel laureates have emerged from the ranks of its scientists, putting it on a par with the best and most prestigious research institutions worldwide. The more than 15,000 publications each year in internationally renowned scientific journals are proof of the outstanding research work conducted at Max Planck Institutes – and many of those articles are among the most-cited publications in the relevant field.

    What is the basis of this success? The scientific attractiveness of the Max Planck Society is based on its understanding of research: Max Planck Institutes are built up solely around the world’s leading researchers. They themselves define their research subjects and are given the best working conditions, as well as free reign in selecting their staff. This is the core of the Harnack principle, which dates back to Adolph von Harnack, the first president of the Kaiser Wilhelm Society, which was established in 1911. This principle has been successfully applied for nearly one hundred years. The Max Planck Society continues the tradition of its predecessor institution with this structural principle of the person-centered research organization.

    The currently 83 Max Planck Institutes and facilities conduct basic research in the service of the general public in the natural sciences, life sciences, social sciences, and the humanities. Max Planck Institutes focus on research fields that are particularly innovative, or that are especially demanding in terms of funding or time requirements. And their research spectrum is continually evolving: new institutes are established to find answers to seminal, forward-looking scientific questions, while others are closed when, for example, their research field has been widely established at universities. This continuous renewal preserves the scope the Max Planck Society needs to react quickly to pioneering scientific developments.

     
  • richardmitnick 7:53 am on June 14, 2017 Permalink | Reply
    Tags: , DESY Petra III, Jumping crystals produce sound waves, Martensitic transformation in steel, , Thermosalient crystals   

    From DESY: “Jumping crystals produce sound waves” 

    DESY
    DESY

    2017/06/14

    1
    Structure shift in a thermosalient crystal: Upon heating, the position of the atoms shifts from red to green. Credit: Manas K. Panda/Panče Naumov, New York University Abu Dhabi

    Scientists have been fascinated by thermosalient crystals for some time: when placed on a hotplate, these inconspicuous crystals suddenly propel themselves upwards, leaping to heights several times their own length. This abrupt movement is caused by a change in the structure of the crystals. A detailed examination of this transition is very difficult because it is so rapid. Now, scientists have resorted to a new technique and discovered that immediately before altering their structure the crystals emit a sound wave, the analysis of which reveals further details about this exciting phase transition. On top of this, the researchers studied the change in the crystal structure very carefully at DESY. The international team of research scientists, headed by Panče Naumov from the New York University Abu Dhabi of the United Arab Emirates, have reported their findings in the journal Angewandte Chemie International Edition.

    Like all crystals, thermosalient crystals are made up of a regular array of molecules. When the crystals are heated above a certain temperature (or cooled below it), their structure changes, scientists call this a phase transition. Although the position of the molecules only shifts very slightly, this happens extremely quickly. “Starting from the origin of the transition, the new phase spreads through the crystal almost like a shock wave,” explains DESY scientist Martin Etter, one of the co-authors of the paper. “This shock wave causes the crystal to move by itself and even to jump.” The energy stored while heating the crystal is released all at once.

    The scientists have now used a new technique to show for the first time that the crystals emit sound waves immediately before undergoing the phase transition. While heating and cooling a certain thermosalient crystal, they managed to measure several waves in the ultrasound range in the vicinity of the transition temperature (around 65 to 67 degrees Celsius on heating and 55 to 53 degrees Celsius on cooling). Normally, the transition is difficult to study with great precision because it takes place so quickly. However, the sound waves offer a means of analysing a number of properties indirectly. For example, the speed of the phase change inside the crystal can be deduced more accurately. The new phase propagates through the crystal at a speed of 2.8 metres per second (about 10 kilometres per hour). The new technique provides much better insights into the individual events occurring during the transition than is possible using other methods.

    2
    Experimental set-up: When the crystal (left) changes its inner structure, a characteristic sound wave (right) can be registered racing through the material. Credit: Manas K. Panda/Panče Naumov, New York University Abu Dhabi

    To find out more about the change in the crystal structure, the scientists also examined the crystals at the P02.1 beamline of DESY’s X-ray source PETRA III.

    DESY Petra III interior

    “If you shine X-rays at a powder made of these crystals during the phase transition, you can use the X-ray diffraction patterns to determine very accurately how the structure is shifting,” says Etter. “This allowed us to determine the precise temperature at which the transition occurred and also revealed that the shift in the molecules’ positions is surprisingly small.”

    The phase change and the subsequent movement of the crystals are based on an exciting mechanism: thermal energy, that is heat, is transformed into mechanical kinetic energy. This energy conversion in crystals could be of interest for a range of applications. “Such materials could perhaps be used as temperature sensors, one day. The phase transition always occurs at a very specific temperature, at which the sensor flips, so to speak,” explains Martin Etter. “Another conceivable application is that of converting heat into electricity; but we are still a long way from achieving this.”

    The scientists are also interested in these crystals for a very different reason. The phase transition takes place in exactly the same way as another process that has so far been observed mainly in metallic materials. The so-called martensitic transformation occurs when steel or certain other alloys are cooled, and displays the same properties as the transition observed in the organic crystals (organic means that they are based on carbon compounds). Measuring the sound waves was intended as a further test to demonstrate the similarity between the two transformations; because such sound waves are also produced during the martensitic transformation. The new findings therefore provide experimental evidence that thermosalient crystals are an organic counterpart to martensites, and that organic solids can behave in similar ways to metals and alloys.

    The Max Planck Institute for Solid State Research in Stuttgart was also involved in this research.

    See the full article here .

    Please help promote STEM in your local schools.

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    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 10:32 am on October 12, 2016 Permalink | Reply
    Tags: , DESY Petra III, Low-bandgap polymers,   

    From DESY: “X-ray vision reveals how polymer solar cells wear out” 

    DESY
    DESY

    2016/10/12

    Scientists from the Technical University of Munich have used the acurate X-ray vision provided by DESY’s radiation source PETRA III to observe the degradation of plastic solar cells.

    DESY Petra III interior
    DESY Petra III

    Their study suggests an approach for improving the manufacturing process to increase the long-term stability of such organic solar cells. The team of Prof. Peter Müller-Buschbaum has presented its findings in the latest issue of the scientific journal Advanced Energy Materials (Vol. 6, No. 19, published online in advance).

    Unlike conventional solar cells, which are made of silicon, organic solar cells produce electricity in an active blended layer between two carbon-based materials. When one of these is a polymer, the resulting cell is often referred to as a plastic solar cell. These are particularly promising because they can be manufactured simply and cheaply. They can be used to make extremely lightweight, flexible and even semi-transparent solar cells using printing techniques on flexible polymer materials, opening up completely new fields of application. In general, however, organic solar cells are less efficient than silicon-based ones, and sometimes they have also a reduced lifetime.

    1
    The inner structure of the active layer without solvent additive (left), with solvent additive (centre) and after loss of solvent additive (right). Losing the solvent leads to an inner structure comparable to production without solvent. Credit: Christoph Schaffer / TU München

    The internal structure of the active layer is crucial in organic solar cells. When manufacturing them, the two materials that form the active layer have to separate out of a common solution, much like droplets of oil forming in water. “It is important that the polymer domains formed in the process are a few tens of nanometres apart,” points out Christoph Schaffer, a PhD student in Müller-Buschbaum’s group, who is the paper’s first author. “Only then positive and negative charge carriers can be efficiently produced in the active layer and separated from each other. If the structure is too coarse or too fine, this process no longer happens, and the efficiency of the solar cell will decrease.” A nanometre is one millionth of a millimetre.

    Modern polymer solar cells often consist of so-called low-bandgap polymers, which absorb particularly large amounts of light. In many cases, these require the use of a solvent additive during the manufacturing process in order to achieve high efficiencies. However, this additive is controversial because it might further decrease the lifetime of the solar cells.

    The scientists used DESY’s X-ray source PETRA III to study the degradation of such low-bandgap polymer solar cells with solvent additives in more detail. To this end, a solar cell of this type was exposed to simulated sunlight in a chamber, while its key parameters were continuously monitored. At the same time, the scientists shone a narrowly collimated x-ray beam from PETRA III at the solar cell at different times, providing a picture of the internal structure of the active layer on a nanometre scale every few minutes. “These measurements can be used to relate the structure to the performance of the solar cell and track it over time,” explains co-author Prof. Stephan Roth, who is in charge of DESY’s P03 beamline, where the experiments were conducted.

    “The data reveals that domains that are on the scale of a few tens of nanometres shrink substantially during operation and that their geometric boundaries with other components disappear,” says Schaffer. At the same time, the measurements suggest that the amount of residual solvent additive decreases. The scientists attribute the measured drop in the efficiency of the solar cell to the observed decrease.

    “Since there is evidence to suggest that the residual amount of solvent additive decreases, we have to assume that this process can limit the lifetime of the solar cells,” explains Müller-Buschbaum. “Therefore it is essential to come up with strategies for stabilising the structure. This could be achieved through chemical bonding between the polymer chains, or using customised encapsulating substances.”

    In an earlier study, the Munich researchers observed the degradation of a different type of polymer solar cell. In that case, the efficiency was found to drop as a result of the active centres gradually growing in size during their operation. This suggested that it is in fact better to manufacture such solar cells with a suboptimal structure, i.e. one that is too fine, so that it can then grow to the optimum size during the first hours of operation.

    The current study picks up the story where the previous one left off. “Our first study showed us that the efficiency dropped when the structure became coarser,” says Schaffer. “Exactly the opposite happens in the present study. This behaviour is precisely what we expected, because the composition of the active layer is different. The materials in the first study tend to demix to a high degree. Here, the opposite is true, and we need the solvent additive in order to achieve the demixing of the materials that is needed to obtain high efficiencies. When the solvent additive disappears during operation, the structure becomes finer and therefore moves away from its optimum.”

    Both these studies offer important approaches to optimising the manufacture of organic solar cells, as co-author Roth points out: “The way these two studies fit together provides a wonderful example of how investigations with synchrotron radiation on the atomic scale yield crucial results, especially in applied research such as in the field of renewable energies.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 8:44 am on July 18, 2016 Permalink | Reply
    Tags: , DESY Petra III, New insights about our Earth’s lower mantle   

    From DESY: “New insights about our Earth’s lower mantle” 

    DESY
    DESY

    2016/07/15
    No writer credit found

    1
    Cystal structure of iron bridgmanite with the iron phase shown in yellow and the silicon oxide phase shown in blue. Credit: Leyla Ismailova/Universität Bayreuth

    Using DESY’s bright X-ray light source PETRA III, a team of scientists has discovered unexpected facts about the most abundant mineral on Earth.

    DESY Petra III
    DESY Petra III interior
    DESY Petra III

    The mineral bridgmanite makes up roughly one third of Earth’s entire volume and is the major component of Earth’s lower mantle. Thus, its physical properties are one of the deciding factors for understanding the dynamics of our planet, with a direct impact on life on Earth’s surface, ranging from deep-focus earthquakes to geochemical cycles leading to formation of mineral deposits. Bridgmanite is rather hard to study under its ‘normal conditions’ that are very high pressures and temperatures. Therefore many properties were discussed controversially within the scientific community.

    The new study revealed that bridgmanite can form an iron-bearing variety which has never been synthesised in laboratories before. This variety can indeed exist throughout the entire mantle and can change the view of the properties of our planet and its behaviour deep underneath the surface, as the team led by Leonid Dubrovinsky from the University of Bayreuth reports in the journal Science Advances. Additionally, the scientists discovered that defects within bridgmanite’s crystal lattice continue to have a significant effect on the material’s properties even under high pressure, which was unexpected.

    “Our Earth is a dynamic planet and we can feel that every day, for example during earthquakes,” explains Hanns-Peter Liermann, head of the Extreme Conditions Beamline P02.2 at PETRA III, where the experiments took place. “Earthquakes can originate from different points within our planet, and in order to understand how they are generated and propagate, we need to understand the dynamics of our planet that are closely related to the minerals present in the interior.” The lower mantle takes up more than half of Earth’s interior, and up to 80 per cent of the lower mantle consist of bridgmanite.

    2
    View of the diamond anvil cell’s interior: the bridgmanite sample is located in the centre. Credit: Elena Bykova, Leyla Ismailova/Universität Bayreuth

    Bridgmanite is a so-called silicate-perovskite, a crystalline structure that is built out of a number of different chemical elements. It mostly consists of the elements magnesium, iron, silicon, aluminium and oxygen which are specifically arranged on an atomic level to form the crystal structure of bridgmanite. “In our high pressure chamber we simulate the conditions within Earth’s lower mantle and observe their influence on the materials. In Earth’s lower mantle very high pressure and temperatures are ‘typical conditions’ for bridgmanite,” explains Dubrovinsky, head of the geo- and material-scientists group of the University of Bayreuth. “Together with colleagues from different synchrotron facilities we’ve developed a unique technique to investigate the crystal structures under these extreme conditions. The crystal structure of bridgmanite is the key to unravel its properties and effects on the dynamics of our planet.”

    The experimental set up that was used for this study was a laser-heated diamond anvil cell (DAC). The bridgmanite crystal is loaded into a small chamber and compressed by specially cut diamonds to reach high pressures. Additionally, laser beams are focused on the crystal to heat it up to 3100 Kelvin (2827 degrees Celsius). In this way the bridgmanite crystal is under high pressure and extreme heat while the X-ray beam is focused onto it. The bridgmanite crystal scatters the X-rays and from the resulting diffraction pattern its crystal lattice structure can be calculated.

    3
    Up to 80 per cent of Earth’s lower mantle is made up of bridgmanite. Credit: DESY

    At extreme pressures of 45 Gigapascals and above, which is 444 115 times the atmospheric pressure and corresponds to a depth of roughly 1350 kilometres below the Earth’s surface, the scientists studied the stability of iron- and aluminum-bearing bridgmanite and found that oxidised iron stabilizes iron-rich bridgmanite. For the first time, they could synthesise bridgmanite with pure iron composition in a lab. This iron bridgmanite has a dramatically low compressibility compared to other bridgmanites, which is a fundamental observation. “This effect could play a major role in explaining lateral seismic heterogeneities in Earth’s lower mantle,” explains Leyla Ismailova, first author of the study from the University of Bayreuth. “Lateral seismic heterogeneities describe the effect that seismic waves do not propagate evenly within the Earth’s lower mantle. The sound velocity of this pure iron bridgmanite is roughly two per cent smaller than in normal bridgmanite. This is especially significant for the interpretation of seismic tomography data and thus for understanding fundamental problems of Earth’s inner structure.”

    4
    Schematic illustration of the experiment set-up. Credit: Hanns-Peter Liermann/DESY

    Reference:
    Stability of Fe,Al-bearing bridgmanite in the lower mantle and synthesis of pure Fe-bridgmanite; Leyla Ismailova, Elena Bykova, Maxim Bykov, Valerio Cerantola, Catherine McCammon, Tiziana Boffa Ballaran, Andrei Bobrov, Ryosuke Sinmyo, Natalia Dubrovinskaia, Konstantin Glazyrin, Hanns-Peter Liermann, Ilya Kupenko, Michael Hanfland, Clemens Prescher, Vitali Prakapenka, Volodymyr Svitlyk, Leonid Dubrovinsky; Science Advances, 2016; DOI: 10.1126/sciadv.1600427

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 7:04 am on April 23, 2015 Permalink | Reply
    Tags: , DESY Petra III, ,   

    From DESY: “Scientists X-ray anti-inflammatory drug candidates” 

    DESY
    DESY

    2015/04/22
    No Writer Credit

    1
    Structure of the Spiegelmer NOX-E36 bound to its target protein CCL2. Credit: Dominik Oberthür/CFEL

    Using DESY’s ultra bright X-ray source PETRA III, scientists have decoded the molecular and three-dimensional structure of two promising drug candidates from the new group of Spiegelmers for the first time.

    DESY Petra III
    DESY Petra III interior
    PETRA III

    The results provide a deeper understanding of the mode of action of these substances that have already entered clinical trials. The researchers from the Universities of Hamburg and Aarhus (Denmark) together with colleagues from the biotech company NOXXON in Berlin present their work in the journal Nature Communications.

    Spiegelmers are a young group of promising pharmaceutical substances. They rely on the same building blocks as the nucleic acids RNA and DNA that fulfil various tasks in the organism – from storing genetic information and messaging to the regulation of genes. Artificial RNA or DNA molecules called aptamers can be tailored to bind to certain proteins with high specificity, blocking their function. Aptamers are well tolerated in the organism as they consist of natural building blocks. For these reasons, aptamers are seen as promising drug candidates. Since 2006, an aptamer for the treatment of age-related macular degeneration [AMD], an eye condition that can lead to blindness, is approved and on the market.

    Usually, RNA and DNA molecules are quickly degraded by enzymes within the body. This severely limits their application as pharmaceutical drugs. However, most biomolecules come in two mirror-image variants, the L-form and the D-form. Natural nucleic acids always exist in the D-form, while proteins are always build in their L-form in the body. Artificial aptamers that are constructed in the naturally not occurring L-form are not degraded by the organism. These mirror-image variants of aptamers are called Spiegelmers. “An advantage of Spiegelmers is that they are not targeted by the body’s enzymes,” explains Prof. Christian Betzel from the University of Hamburg.

    “Spiegelmers can be identified and optimised in the lab through a sophisticated evolutionary procedure. However, exact structure data of Spiegelmers have not been available until now,” says first author Dr. Dominik Oberthür from the Center for Free-Electron Laser Science CFEL, a cooperation of DESY, Max Planck Society and the University of Hamburg. If the exact structure of a Spiegelmer and its binding site at the target protein is known, its mode of action can be decoded and its structure could be further fine-tuned, if necessary.

    The team around Betzel used PETRA III’s bright X-rays to analyse the Spiegelmer NOX-E36 from NOXXON. It blocks the protein CCL2 that is involved in many inflammatory processes in the body. “If you target an inflammatory protein with a Spiegelmer, you have a good chance to tone down the inflammation in the body,” notes Betzel. NOX-E36 has already been successfully tested in a phase IIa clinical trial with patients.

    In order to analyse the structure of the drug candidate, the scientists first had to grow crystals of the Spiegelmer bound to its target protein CCL2. “Growing these crystals was quite a challenge,” recalls Betzel. Because it contradicts their natural function, most biomolecules are notoriously hard to crystallise.

    The crystals were analysed at the PETRA III measuring station P13, run by the European Molecular Biology Laboratory EMBL. Crystals diffract X-ray light, producing a characteristic pattern on the detector. From this diffraction pattern the structure of the crystal’s building blocks can be calculated – in this case the Spiegelmer’s structure, bound to its target protein. In the same manner, a group around Laure Yatime from the University of Aarhus solved the structure of another Spiegelmer: NOX-D20 binds to the protein C5a that is involved into many inflammatory processes, too. The group also reports the structure in Nature Communications.

    The analyses reveal the structure of both Spiegelmers with a spatial resolution of 0.2 nanometres (millionths of a millimetre) – that’s on the order of individual atoms. “I am delighted to finally have a high resolution visualization of the remarkable shapes of two Spiegelmer drug candidates,” comments Dr. Sven Klussmann, founder and chief scientific officer of NOXXON, and also co-author on both articles. “The structural data not only provide the first look at the unusual interaction of a mirror-image oligonucleotide with a natural protein but also deepens our understanding of the two molecules’ mode of action.”

    Reference:
    Crystal structure of a mirror-image L-RNA aptamer (Spiegelmer) in complex with the natural L-protein target CCL2; Dominik Oberthür, John Achenbach, Azat Gabdulkhakov, Klaus Buchner, Christian Maasch, Sven Falke, Dirk Rehders, Sven Klussmann & Christian Betzel; „Nature Communications“, 2015; DOI: 10.1038/ncomms7923

    Structural basis for the targeting of complement anaphylatoxin C5a using a mixed L-RNA/L-DNA aptamer; Laure Yatime, Christian Maasch, Kai Hoehlig, Sven Klussmann, Gregers R. Andersen & Axel Vater; „Nature Communications“, 2015; DOI: 10.1038/ncomms7481

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 3:05 pm on April 21, 2015 Permalink | Reply
    Tags: , DESY Petra III,   

    From DESY: “Ultrafast tracking of electron spins” 

    DESY
    DESY

    2015/04/21
    No Writer Credit

    Our present digital information processing and storage is based on two properties of the electron. The first is its charge, which is used in electronic circuits to process information. The second is its spin, which represents the information stored on a magnetic hard disk. Recent research attempts to make use of the charge and the spin of the electron simultaneously. This approach could enhance functionality, capacitance, energy consumption and speed of today’s information technology.

    1
    A microscope image of the magnetic sample, showing the bright track of the X-ray beam. Credit: Lars Bocklage/DESY

    Researchers from DESY, from the Max-Planck-Institute for Structure and Dynamics of Matter, and from the University of Hamburg have now made a big step towards tracking the electron spin at very high frequencies that are technologically important. The team used the extremely brilliant X-rays generated at DESY’s PETRA III facility, to read out a nuclear sensor placed in the investigated magnetic material.

    DESI Petra III
    DESI Petra III interior
    PETRA III

    In this way they could determine the motion of the, as the researchers report in the journal Physical Review Letters.

    ”The actual orbit of the spin is important as it determines many of the spin related effects that are under research now and proposed for new functional devices“, explains main author Lars Bocklage from DESY, who is also a member of the Hamburg Centre for Ultrafast Imaging (CUI). “Especially for data processing and mobile communication high frequencies are of importance. But even the fastest microscopy techniques available to determine spin motions reach their limit when it comes to the Gigahertz regime used in the present experiment.” A Gigahertz corresponds to a billion cycles per second.

    The trick in the new work is the use of a certain isotope of iron that contains one neutron more than the most prevalent iron isotope in nature. It can absorb X-rays of a specific energy, but reemits the X-ray after a very short time. This technique is called nuclear resonant scattering. The team around Bocklage found out in which way the X-ray emission is influenced by the motion of the spin. “This way the spin leaves a fingerprint in the photons emitted from the iron isotope, and the orbit of the spin can be identified,” explains Bocklage.

    The system that was investigated is a 13 nanometres (millionths of a millimetre) thin ferromagnetic film of nickel and iron, an alloy called Permalloy. The material was excited with an external magnetic high-frequency field that initiates a precession of the spins. This means the spin axes reel like a child’s top that has been nudged sideways. The exact motion of the spin was not known up to now. The investigations show that the shape and the amplitude can be precisely determined.

    “The spins perform an elliptical motion in the thin film which has many implications for the research fields of spintronics, spin caloritronics, and magnonics as well as for the theoretical models that describe spin related effects,” reports Bocklage. “With the given nuclear scattering technique and the findings on the spin motion, systems can be tuned to optimize the orbit of the spin and with it the functionality of future spin-based devices.”

    Reference:
    Spin Precession Mapping at Ferromagnetic Resonance via Nuclear Resonant Scattering of Synchrotron Radiation; Lars Bocklage, Christian Swoboda, Kai Schlage, Hans-Christian Wille, Liudmila Dzemiantsova, Saša Bajt, Guido Meier, and Ralf Röhlsberger; “Physical Review Letters”, 2015; DOI: 10.1103/PhysRevLett.114.147601

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

     
  • richardmitnick 8:36 pm on November 4, 2014 Permalink | Reply
    Tags: , , , DESY Petra III   

    From DESY: “Photosynthesis in X-ray Vision” 

    DESY
    DESY

    04.11.2014
    No Writer Credit

    New technology facilitates analysis of biomolecules in a near-natural state

    Photosynthesis is one of the most important processes in nature. The complex method with which all green plants harvest sunlight and thereby produce the oxygen in our air is, however, still not fully understood. Researchers using DESY’s X-ray light source PETRA III have examined a photosynthesis subsystem in a near-natural state. According to the scientists led by Privatdozentin Dr. Athina Zouni from the Humboldt University (HU) Berlin, the X-ray experiments on what is known as photosystem II reveal, for example, yet unknown structures. Their results are published in the scientific journal Structure. The technology utilised could also be of interest for analysing other biomolecules.

    six
    Molecular structure of photosystem II, which arranges itself in rows. Credit: Martin Bommer/HU Berlin

    DESI Petra III
    DESI Petra III interior
    DESI Petra III

    Photosystem II forms part of the photosynthetic machinery where water, with the help of sunlight, is split into hydrogen and oxygen. As one of the membrane proteins, it sits in the cell membrane. Membrane proteins are a large and vital group of biomolecules that are, for example, important in addressing a variety of medical issues. In order to decode the protein structure and reveal details on how biomolecules function, researchers use the very bright and short-wave X-rays of PETRA III and other similar facilities. Small crystals, however, must initially be grown from these biomolecules. “The structure of single molecules cannot be directly seen even with the brightest X-rays,” explains co-author and DESY researcher Dr. Anja Burkhardt of Measuring Station P11, where the experiments were carried out. “In a crystal, however, a multitude of these molecules are arranged in a highly symmetrical fashion. Thus the signal, resulting from X-ray diffraction of these molecules, is amplified. The molecular structure can then be calculated from the diffraction images.”

    Biomolecules – and especially membrane proteins – cannot easily be compelled into crystal form as it is contrary to their natural state. Preparing suitable samples is therefore a crucial step in the whole analysis process. For instance, photosystem II must be first separated from the membrane, where it is bound to numerous small fat molecules (lipids). Researchers use special detergents for this purpose, such as those also principally found in soap. The catch: instead of lipids, the biomolecules are now surrounded by detergents, which may make the crystals spongy under certain conditions, thus exacerbating the analysis. “What we want is to come as close as possible to nature,” stresses Zouni. The closer the proteins in the crystal are to their natural state, the better the results.

    The group led by Zouni has now managed to produce photosystem II crystals, which no longer contain detergents so that the biomolecules are frozen in a near-natural state. “The trick was to use a detergent that strongly differs from the lipids in composition and structure,” explains the researcher. Before examining the biomolecular crystals using X-rays, a portion of the water is extracted and replaced by an anti-freeze. The crystals are usually frozen for the experiments because the high-energy X-ray doesn’t damage them so quickly in the frozen state. During this process, the researchers would like to avoid ice formation. “The dehydration process removed not only the water in our samples, but also completely removed the detergent, something we didn’t expect,” says Zouni.“Our samples are closer to the natural state than what has been reported before.”

    Consequently, the investigation’s spatial resolution increased from about 0.6 nanometres (a millionth of a millimetre) to 0.244 nanometres. This is not, in fact, the highest resolution ever achieved in a photosystem II study, but the analysis shows that the photosystem II proteins are arranged within the crystals as pairs of rows, something that also occurs in the natural environment.

    Electron microscope investigations by Professor Egbert Boekema’s group at the University of Groningen in the Netherlands had already shown the photosystems’ crystal like arrangement in the natural membrane — a kind of tiny solar cell. Electron microscopy could better recognize connections using direct observation of the native membrane while X-ray crystallography could reveal the smallest details. “We placed the structural data over the electron microscope images – they matched precisely,” says Zouni. The investigation also revealed structures that were invisible before. “We can see exactly where the bonds to the lipids are located,” the scientist explains. The more the researchers discover about photosystem II, the better they understand exactly how it functions.

    The procedure of using a new detergent, however, is not only interesting in terms of photosystem II. “The method can potentially be applied to many membrane proteins,” stresses Zouni. In the future, many biomolecules could maybe examined in a more natural state than ever before.

    See the full article here.

    desi

    DESY is one of the world’s leading accelerator centres. Researchers use the large-scale facilities at DESY to explore the microcosm in all its variety – from the interactions of tiny elementary particles and the behaviour of new types of nanomaterials to biomolecular processes that are essential to life. The accelerators and detectors that DESY develops and builds are unique research tools. The facilities generate the world’s most intense X-ray light, accelerate particles to record energies and open completely new windows onto the universe. 
That makes DESY not only a magnet for more than 3000 guest researchers from over 40 countries every year, but also a coveted partner for national and international cooperations. Committed young researchers find an exciting interdisciplinary setting at DESY. The research centre offers specialized training for a large number of professions. DESY cooperates with industry and business to promote new technologies that will benefit society and encourage innovations. This also benefits the metropolitan regions of the two DESY locations, Hamburg and Zeuthen near Berlin.

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