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Redox-transformation kinetics of aqueous thio-arsenic species…

2018/06/302018/07/04

… determining arsenic sequestration by organic thiol groups of peat.

Arsenic (As) is a toxic metalloid which has attracted the attention of the general public because of its natural toxic concentrations in drinking water of millions of people around the world. The mobility and bioavailability of As thereby strongly depends on redox conditions, often linked to the redox cycles of sulfur (S), iron (Fe), and carbon (C). In reducing systems such as wetlands (swamps, peatlands, paddy fields etc.) As is thought to be mainly present in its reduced trivalent form as arsenite. Naturally, these systems are rich in natural organic matter (NOM) because mineralization of carbon is delayed under anoxic, reducing conditions. Furthermore sulfur, which acts as a main nutrient for plants, can also be present in its reduced forms as e.g. organic thiol groups in NOM-rich environments after anoxic decomposition of plant debris or reduction of released sulfate.

Figure: (extract) Proposed conceptual model for the As-S chemistry in the minerotrophic peatland Gola di Lago, Switzerland. Scenario 1: arsenate and arsenite prevail as long as no reduced inorganic sulfur is present. Scenario 2: monothioarsenate formation from arsenite and surface-bound zerovalent sulfur species. Scenario 3: formation of higher thiolated arsenates from monothioarsenate under conditions of available free sulfide. (…) Entire figure and information here
Credit: Besold et al. 2018, ES&T, DOI: 10.1021/acs.est.8b01542, Copyright 2018, American Chemical Society.

Advanced imaging technique used to study triggers of tree mortality

2018/06/292018/07/04

Researchers are using advanced imaging technologies similar to those used in hospitals, including micro-computed tomography on the Imaging and Medical beamline (IMBL) at the Australian Synchrotron, to determine how vulnerable our trees are to drought and heatwaves.
A new scientific review published In Nature outlines progress towards understanding the likely risks from droughts and heatwaves that combine to kill millions of trees around the world with spectacular effects on the environment.

Recent drought and heatwave conditions in northern Australia have killed more than 7000ha of mangrove forests, leaving these essential ecosystems stark, grey skeletons of trees. In California, the prolonged drought period has killed more than 100 million trees that increase the intensity of wildfires and impact on the region’s beauty, tourism and environmental health.
Dead trees, of course, cannot store carbon out of the air and the enormous numbers of dead trees release large quantities of stored carbon back into the air as they are burned or decay, further amplifying the effects of rising carbon dioxide.

Image: IMBL robot positions the tree for imaging.

ALBA invites primary school students to experiment with science

2018/06/292018/07/12

Mision ALBA is an educational project beginning next academic year and a maximum of 250 primary school groups of 5th and 6th grade from all over Spain will be able to participate.

One mission, four phases: matter, force, energy and light. ALBA is looking for boys and girls to accept the challenge of dealing with synchrotron science! From now on, their teachers can register their groups at www.misionalba.es. The educational project is launched for the first time during the academic year 2018-2019 and up to 5,000 students can participate, totally free. The contents of the Misión ALBA respond to the demands of the official curriculum for this educational stage, including educational guidelines adapted for each autonomous region.

Nobel Prize Barry C. Barish visits ALBA

2018/06/292018/07/11

The Nobel Laureate in Physics for his role in the detection of gravitational waves has visited today the facility.

Accompanied by the director, Caterina Biscari, Ramon Pascual, honorary president, other members of the ALBA management and Enrique Fernández, former director of IFAE, Barry C. Barish has had the opportunity to visit the experimental hall and talk to different researchers who are performing their experiments this week at ALBA.

>Read more on the ALBA website

Picture: (from left to right), Enrique Fernández – former director of IFAE -, Barry C. Barish, Caterina Biscari and Ramon Pascual.

The quest for atomic perfection in semiconductor devices

2018/06/292018/07/12

A research team, including scientists from MAX IV have reported in Nature Communications that the quest for atomic perfection in semiconductor devices was based on an oversimplified model.

Semiconductors are the fundamental building blocks of all modern electronics. Improvements to these materials could affect everything from the clock on our microwave to supercomputers used to crunch big data. The search to make them better involves looking at atomic level changes in semiconductor materials in order to understand how they could be improved, and even made perfect.

The problem with semiconductors and the way they are manufactured is that they need to be processed with metal contacts and thin insulating layers, and the interface between the semiconductor and these contacts contains a lot of defects which hamper device performance. If scientists can find a way to reduce the defects or eliminate them completely, then semiconductors could conceivably become faster and smaller. The problem is, these defects occur on the atomic scale and are very difficult to measure.

Scientists working at Max Lab, the predecessor to the newly built MAX IV, together with physicists from Lund University used the SPECIES beamline to investigate a common semiconductor synthesis method. Hafnium dioxide was deposited on the surface of indium arsenide and monitored using ambient pressure X-ray photoelectron spectroscopy (APXPS). The scientists were able to monitor the very first atomic layer that was deposited, and monitor the chemical reactions that were occurring as the process was underway.

Google Maps for the cerebellum

2018/06/282018/07/12

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.

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

The machinist: A maker finds his calling in upstate New York

2018/06/272018/07/05

Join John Buettler, a machinist, as he shares the passion he brings to the job of helping to construct the Cornell High Energy Synchrotron Source (CHESS). CHESS is a high-intensity X-ray source, primarily supported by the National Science Foundation, that provides users with state-of-the-art synchrotron radiation facilities for research in physics, chemistry, biology and environmental and materials sciences.

Provided by Cornell University
Runtime: 3:41

Magnetization ratchet in cylindrical nanowires

2018/06/262018/07/11

A team of researchers from Materials Science Institute of Madrid (CSIC), University of Barcelona and ALBA Synchrotron reported on magnetization ratchet effect observed for the first time in cylindrical magnetic nanowires (magnetic cylinders with diameters of 120nm and lengths of over 20µm).

These nanowires are considered as building blocks for future 3D (vertical) electronic and information storage devices as well as for applications in biological sensing and medicine. The experiments have been carried out at the CIRCE beamline of the ALBA Synchrotron. The results are published in ACS Nano.

The magnetic ratchet effect, which represents a linear or rotary motion of domain walls in only one direction preventing it in the opposite one, originates in the asymmetric energy barrier or pinning sites. Up to now it has been achieved only in limited number of lithographically engineered planar nanostructures. The aim of the experiment was to design and prove the one-directional propagation of magnetic domain walls in cylindrical nanowires.

>Read more on the ALBA website

Image: (extract) Unidirectional propagation of magnetization as seen in micromagnetic simulations and XMCD-PEEM experiments. See entire image here.

Dark-field X-ray microscopy provides surprising insight on ferroelectrics

2018/06/252018/07/04

Thanks to the unique capabilities of in-situ dark-field X-ray microscopy, scientists have now been able to see the complex structures hidden deep inside ferroelectric materials. The results, published today in Nature Materials, contradict previous studies in which only the surface was studied. This revolutionary new technique will be the main feature of a new beamline for the new EBS machine currently being built at the ESRF.

“Until now we could only see the surface of the material; dark-field x-ray microscopy is like creating a window to its interior”, explains Hugh Simons, assistant professor at the Technical University of Denmark and corresponding author of the study. “It provides incredible contrast for even the subtlest structures inside these materials, giving us a much clearer picture of how they work”, he adds.

Simons, together with the team of ID06 – the beamline where the technique is being developed – studied the ferroelectric material BaTiO₃, which is used every day in cars, computers and mobile phones. By imaging their internal structure at the same time as they applied an electric field on it, they could see how these internal structures behave and change dynamically.

Image: (extract) Crosssectional dark-field x-ray microscopy maps of the embedded BaTiO₃ grain. (…) the reconstructed strain map reveals the structural relationship between domain clusters. Full picture here.
Credit: H. Simons.

Synchrotron researchers uncover lost images from the 19th century

2018/06/222018/06/27

Art curators will be able to recover images on daguerreotypes, the earliest form of photography that used silver plates, after scientists learned how to use light to see through degradation that has occurred over time.

Research published today in Scientific Reports includes two images from the National Gallery of Canada’s photography research unit that show photographs that were taken, perhaps as early as 1850, but were no longer visible because of tarnish and other damage. The retrieved images, one of a woman and the other of a man, were beyond recognition. “It’s somewhat haunting because they are anonymous and yet it is striking at the same time,” said Madalena Kozachuk, a PhD student in the Department of Chemistry at Western University and lead author of the scientific paper.

“The image is totally unexpected because you don’t see it on the plate at all. It’s hidden behind time. But then we see it and we can see such fine details: the eyes, the folds of the clothing, the detailed embroidered patterns of the table cloth.”
The identities of the woman and the man are not known. It’s possible that the plates were produced in the United States, but they could be from Europe.
For the past three years, Kozachuk and an interdisciplinary team of scientists have been exploring how to use synchrotron technology to learn more about chemical changes that damage daguerreotypes.

Image: A mounted daguerreotype resting on the outside of the vacuum chamber within the SXRMB (a beamline at CLS) hutch.
Credit: Madalena Kozachuk.

Probing the complex dielectric properties of MOFs

2018/06/222018/07/18

Gaining fundamental insights into the full dielectric behaviour of MOFs across the infrared and THz.

An international team of researchers from Oxford, Diamond, and Turin, has demonstrated the novel use of synchrotron radiation infrared (SRIR) reflectivity experiments, to measure the complex and broadband dielectric properties of metal-organic framework (MOFs) materials. Open framework compounds like MOFs have the potential to revolutionise the field of low-k dielectrics, because of their tuneable porosity coupled with an enormous combination of physicochemical properties not found in conventional systems. Furthermore, next generation IR optical sensors and high-speed terahertz (THz) communication technologies will stand to benefit from an improved understanding of the fundamental structure-property relations underpinning novel THz dielectric materials.

Image: (extract) The high-resolution reflectivity data obtained were subsequently used to determine the real and imaginary components of the complex dielectric function by adopting the Kramers−Kronig Transformation theory.
Credit: ACS

Enlightening yellow in art

2018/06/212018/06/21

Scientists from the University of Perugia (Italy), CNR (Italy), University of Antwerp, the ESRF and DESY, have discovered how masterpieces degrade over time in a new study with mock-up paints carried out at synchrotrons ESRF and DESY. Humidity, coupled with light, appear to be the culprits.

The Scream by Munch, Flowers in a blue vase by Van Gogh or Joy of Life by Matisse, all have something in common: their cadmium yellow pigment. Throughout the years, this colour has faded into a whitish tone and, in some instances, crusts of the paint have arisen, as well as changes in the morphological properties of the paint, such as flaking or crumbling. Conservators and researchers have come to the rescue though, and they are currently using synchrotron techniques to study in depth these sulphide pigments and to find a solution to preserve them in the long run.

“This research has allowed us to make some progress. However, it is very difficult for us to pinpoint to what causes the yellow to go white as we don’t have all the information about how or where the paintings have been kept since they were done in the 19^th century”, explains Letizia Monico, scientist from the University of Perugia and the CNR-ISTM. Indeed, limited knowledge of the environmental conditions (e.g., humidity, light, temperature…) in which paintings were stored or displayed over extended periods of time and the heterogeneous chemical composition of paint layers (often rendered more complex by later restoration interventions) hamper a thorough understanding of the overall degradation process.

>Read more on the ESRF website

Image: Some of the mock-up paints, prepared by Letizia Monico. Credits: C. Argoud.

Berkeley Lab researchers receive DOE Early Career Research Awards

2018/06/212018/07/04

Six scientists at Lawrence Berkeley National Laboratory (Berkeley Lab) have been selected by the U.S. Department of Energy’s (DOE’s) Office of Science to receive significant funding for research through its Early Career Research Program.

The program, now in its ninth year, is designed to bolster the nation’s scientific workforce by providing support to exceptional researchers during the crucial early career years, when many scientists do their most formative work. The six Berkeley Lab recipients are among a total of 84 recipients selected this year, including 30 from DOE’s national laboratories. This year’s awards bring to 35 the total number of Berkeley Lab scientists who have received Early Career Research Program awards since 2010.

“We are grateful that DOE has chosen to recognize these six young Berkeley Lab scientists,” said Berkeley Lab Director Mike Witherell. “Our Lab takes very seriously the responsibility to train the next generation of scientists and engineers. Each of their proposed projects not only represents cutting-edge science but will also contribute to our understanding of the world and a sustainable future.“

The scientists are each expected to receive grants of up to $2.5 million over five years to cover year-round salary plus research expenses.

Image: Ethan Crumlin is a staff scientist at the Advanced Light Source (ALS), a DOE Office of Science User Facility at Berkeley Lab, who specializes in studies of chemistry at the interfaces between solids, liquids, and gases.

Brookhaven Lab scientist receives Early Career Research Program Funding

2018/06/212018/07/04

Valentina Bisogni, an associate physicist at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, has been selected by DOE’s Office of Science to receive significant research funding as part of DOE’s Early Career Research Program.

The effort, now in its ninth year, is designed to bolster the nation’s scientific workforce by providing support to exceptional researchers during the crucial early career years, when many scientists do their most formative work. Bisogni is among a total of 84 recipients selected this year after a competitive review of proposals. Thirty winners come from DOE national laboratories and 54 from U.S. universities.

“Supporting talented researchers early in their career is key to building and maintaining a skilled and effective scientific workforce for the nation. By investing in the next generation of scientific researchers, we are supporting lifelong discovery science to fuel the nation’s innovation system,” said Secretary of Energy Rick Perry. “We are proud of the accomplishments these young scientists have already made, and look forward to following their achievements in years to come.”

Each researcher will receive a grant of up to $2.5 million over five years to cover their salary and research expenses. A list of the 84 awardees, their institutions, and titles of their research projects is available on DOE’s Early Career Research Program webpage.

Image: Valentina Bisogni is shown preparing samples at NSLS-II’s Soft Inelastic X-ray Scattering beamline, where she will conduct her research funded through DOE’s Early Career Research Program.

The 2018 Julian David Baumert Ph.D. Thesis Award

2018/06/212018/06/21

Maxwell Terban received the 2018 Julian Baumert Ph.D. Thesis Award at this year’s Joint CFN and NSLS-II Users’ Meeting.

Maxwell Terban, a postdoctoral researcher at the Max-Plank Institute for Solid State Research, Stuttgart, is this year’s recipient of the Julian Baumert Ph.D. Thesis Award. Terban was selected for developing new research methods, based around a technique called pair distribution function (PDF), for extracting and analyzing structural signatures from materials. His research incorporated measurements from the now-closed National Synchrotron Light Source (NSLS) and the recently opened National Synchrotron Light Source II (NSLS-II)—a U.S. Department of Energy (DOE) Office of Science User Facility located at Brookhaven National Laboratory.

Each year, the Baumert Award is given to a researcher who has recently conducted a thesis project that included measurements at NSLS or NSLS-II. The award was established in memory of Julian David Baumert, a young Brookhaven physicist who worked on x-ray studies of soft-matter interfaces at NSLS.

Terban holds a bachelor’s degree in chemical engineering from the University of Massachusetts, Amherst, and a master’s degree in materials science and engineering from Columbia University. He graduated with a Ph.D. in materials science and engineering from Columbia University in 2018, and completed his doctoral dissertation under the guidance of Simon Billinge, a professor of materials science and engineering and applied physics and mathematics at Columbia.

Image: Maxwell Terban, a postdoctoral researcher at the Max-Plank Institute for Solid State Research, Stuttgart, is this year’s recipient of the Julian Baumert Ph.D. Thesis Award.

Movie directors with extra roles

2018/06/202018/06/27

Data storage devices based on novel materials are expected to make it possible to record information in a smaller space, at higher speed, and with greater energy efficiency than ever before.

Movies shot with the X-ray laser show what happens inside potential new storage media, as well as how the processes by which the material switches between two states can be optimised.
Henrik Lemke comes to work on his bicycle. Private cars are not allowed to drive to the SwissFEL building in the Würenlingen forest, and delivery vans and lorries need a permit. As a beamline scientist, the physicist is responsible for the experiment station named for Switzerland’s Bernina Pass. At the end of 2017, he led the first experiment at the Swiss free-electron X-ray laser, acting in effect as a movie director while SwissFEL was used, like a high-speed camera, to record how a material was selectively converted from a semiconducting to a conducting state – and back again. To this end the PSI team, together with a research group from the University of Rennes in France, studied a powder of nanocrystals made of titanium pentoxide. The sample was illuminated with infrared laser pulses that made the substance change its properties. Then X-ray pulses revealed how the crystal structure was deformed and enlarged – a cascade of dynamic processes that evidently depend on the size of the crystals.

Image: The directors: Henrik Lemke and Gerhard Ingold
Credit: Scanderbeg Sauer Photography