Taiwan Light Source (TLS, 1.5 GeV) and Taiwan Photon Source (TPS, 3.0 GeV) are the two synchrotron light sources currently operated by the National Synchrotron Radiation Research Center (NSRRC). There are around 13,000 academic user visits to NSRRC every year; approximately 10% are international.
… 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.
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.
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.
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.
Picture: (from left to right), Enrique Fernández – former director of IFAE -, Barry C. Barish, Caterina Biscari and Ramon Pascual.
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.
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
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.
Image: (extract) Unidirectional propagation of magnetization as seen in micromagnetic simulations and XMCD-PEEM experiments. See entire image here.
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.