Latest-News – Page 119 – Lightsources.org

Ferromagnetic and antiferromagnetic coupling of spin molecular interfaces

2018/05/282018/05/31

Researchers from the physics department of the Università “La Sapienza” in Rome, Centro S3 of Modena and ALBA, have demonstrated that magnetic coupling of metal-organic molecules to a magnetic substrate mediated by a graphene layer can be tuned in strength and direction by choosing the symmetry of the molecular orbitals that is largely preserved thanks to the graphene layer. The results have been published in the journal Nano Letters.

Paramagnetic molecules become potential building blocks in spintronics when their magnetic moments are stabilized against thermal fluctuations, for example, by a controlled interaction with a magnetic substrate. Spin molecular interfaces with preserved magnetic activity and exhibiting magnetic remanence at room temperature (RT) can open the route to engineer highly spin-polarized, nanoscale current sources. The need to fully control the organic spin interface and the tuning of ferromagnetic (FM) or antiferromagnetic (AFM) coupling to achieve a stable conductance has motivated a vast experimental interest.

>Read more on the ALBA website

Image: Figure 1: a,b) Antiferromagnetic/Ferromagnetic coupling as deduced by element-specific hysteresis loops of a FePc and CuPc (respectively) to a Cobalt layer with perpendicular magnetic anisotropy intercalated below graphene. c,d) orbital-porjection of the spin-density for the FePc and CoPc interface reflecting the different symmetry of the molecular orbitals involved in the ferromagnetic and antiferromagnetic interaction.

The power supplies giving Diamond a boost

2018/05/242018/05/25

The electrons that produce Diamond’s ultra-bright light whizz round the storage ring fast enough to travel around the entire world 7.5 times in a single second. But they don’t start out life super speedy, and they need a huge energy boost to get them ready for work!

Diamond’s electrons are generated in the injection system, where they are produced by a glowing filament (just like a dim light bulb) and accelerated to ninety thousand electron volts (90 keV). From there, a linear accelerator (linac) takes over, accelerating the electrons to a hundred million electron volts (100 MeV, or 0.1 GeV).

That’s not fast enough though, so the electrons from the linac are fed into the booster ring, where they’re are accelerated to 3 GeV by passing through an RF cavity millions of times. It’s like microwaving the electrons to get them to accelerate, which is not an easy task. The electrons want to travel in a straight line, and have to be forced to bend around the ring by dipole bending magnets. As the energy of the electrons increases, it gets harder to keep them moving around the booster ring, and the bending magnets need more power.

Image: Members of the Power Supply team working in the Booster Supply Hall.

Rational optimization of organic solar-cell materials

2018/05/222018/06/07

The work suggests a way to quickly identify ideal material mixtures and processing methods, bypassing trial-and-error strategies and minimizing labor-intensive synthesis.

To generate electricity from light, the photoactive layer of an organic solar cell (OSC) must allow the photoexcitation and separation of charges, something that can happen in blends of electron-donating and electron-accepting organic materials. Not surprisingly, such blends have been created in steady succession with the goal of improving device efficiency.

However, there are over a thousand combinations of electron donors and acceptors available for use in OSCs and countless processing variations. The reliance on trial and error to identify the best materials and methods is a serious limitation. A way to predict device efficiency based on easily measurable or derivable parameters would go a long way toward streamlining the process.

Image: (extract) Artistic interpretation of an organic solar-cell mixture containing a blend of polymers and fullerenes. Interactions between these molecules (represented by the interaction parameter, χ) affect the degree of mixing that occurs, which in turn is key to device performance.

Taking additive manufacturing’s heart beat

2018/05/212018/05/22

Additive manufacturing, or 3D printing, builds objects by adding layers and it is emerging as a more flexible and reliable way of manufacturing complex structures in the aerospace, engineering and biomedical industries. A British team is at the ESRF’s ID19 to see into the heart of the process and understand it.

“I would not want to ship this equipment on an aeroplane”, Chu Lun Alex Leung said, scientist from the University of Manchester. “It was too precious to leave it in the hands of third parties”, he added. Instead of coming to the ESRF by aeroplane, Leung and his colleagues endured the 12-hour drive in a rental van all the way from Oxfordshire (UK) to the ESRF to make sure their unique equipment arrived safely.

Leung was referring to the laser additive manufacturing (LAM) process replicator, or LAMPR for short, a machine himself and colleagues at the Research Complex at Harwell have developed that 3D prints polymers, metals and ceramics while ESRF’s X-rays probe the heart of the process – the melting and solidification of powders to form complex 3D printed components.

Image: The team on the beamline, next to the laser additive manufacturing (LAM) process replicator. Front row: Margie P. Olbinado, Yunhui Chen. Back row: Sam Tammas-Williams, Lorna Sinclair, Peter D. Lee, Chu lun alex Leung, Samuel Clark, Sebastian Marussi.
Credit: C.Argoud

A day as a young scientist

2018/05/182018/05/25

Physics isn’t everyone’s favourite subject. At the iLab of the Paul Scherrer Institute PSI, students experience the material in a different way: with experiments instead of memorising formulas.

Beat Henrich likes to use the Big Bang to explain the benefits of spectrometry to his adolescent guests. We know that everything in our universe is constantly moving apart, he says to the 17 students at the experiment station of the school laboratory iLab, only because we can measure the light of other galaxies. But because not all processes in the universe can be explained by matter that generates or reflects light, Henrich continues, scientists are currently investigating the “dark matter”, the big mystery in the history of the universe’s origins. If you make a discovery there, the head of iLab concludes, you would be candidates for the Nobel Prize.Is there a future Nobel laureate sitting here? Or a future top researcher? Michael Portmann, a physics teacher at the cantonal high school Alpenquai in Lucerne, casts a glance at the students of his two classes with whom he travelled to PSI today. Naturally, it’s too soon to tell, says Portmann, who has taught physics for 15 years and knows of a just handful of his former students who went on to study his subject later. But here it does show who is open to research.

Image: The school laboratory iLab gives young people an insight into the world of research.
Credit: Paul Scherrer Institute/Markus Fischer

How dolphins could potentially lead to new antibiotics

2018/05/172018/05/18

The world is currently living through a multidrug resistance problem, where antibiotics that traditionally work are not effective anymore. A European team of scientists at the University of Hamburg (Germany), University of Munich (Germany), University of Bordeaux (France), University of Trieste (Italy) and University of London (UK) have studied how some peptides in dolphins target bacterial ribosomes and hence, could provide clues about potential new antibiotics.

Proline-rich antimicrobial peptides (PrAMPs) are antibacterial components of the immune systems of animals such as honey bees, cows and, as this study proves, bottlenose dolphins. These peptides are a first response for the killing of bacteria. In humans, antimicrobial peptides (AMPs) mainly kill bacteria by disrupting the bacterial cell membrane, but so far no evidence of PrAMPs has been found. PrAMPs have a different mechanism of action to AMPs: they pass through the membrane of the cell without perturbing it and bind to ribosomes to inhibit protein synthesis.

The European team have been studying the mechanism of action of bacteria killing peptides in animals: “We want to compare PrAMPs from different organisms to mechanistically understand how these peptides inhibit bacteria”, Daniel Wilson explains.

Illustration showing the mechanism of Tur1A. (entire image: here)
Credits: D. Wilson

Metallic drivers of Alzheimer’s disease

2018/05/172018/05/18

The detection of iron and calcium compounds in amyloid plaque cores

X-ray spectromicroscopy at the Scanning X-ray Microscopy beamline (I08), here at Diamond, has been utilised to pinpoint chemically reduced iron and calcium compounds within protein plaques derived from brains of Alzheimer’s disease patients. The study, published in Nanoscale, has shed light on the way in which metallic species contribute to the pathogenesis of Alzheimer’s disease and could help direct future therapies.

Alzheimer’s disease is a neurodegenerative disease that is associated with dementia and shortened life expectancy. The disease is characterised by the formation of protein plaques and tangles in the brain that impair function. As well as protein plaques, perturbed metal ion homeostasis is also linked with pathogenesis, and iron levels in particular are elevated in certain regions of the brain.

A team of scientists with a long history in exploring biomineralisation in Alzheimer’s brains set out to characterise the iron species that are associated with the amyloid protein plaques. They extracted samples from the brains of two deceased patients who had Alzheimer’s and applied synchrotron X-ray spectromicroscopy to differentiate the iron oxide phases in the samples.

They noted evidence that the chemical reduction of iron, and indeed the formation of a magnetic iron oxide called magnetite, which is not commonly found in the human brain, had occurred during amyloid plaque formation, a finding that could help inform the outcomes of future Alzheimer’s therapies.

Image: Synchrotron soft X-ray nano-imaging and spectromicroscopy reveals iron and calcium biomineralisation in Alzheimer’s disease amyloid plaques.

World’s strongest bio-material outperforms steel and spider silk

2018/05/162018/05/18

Novel method transfers superior nanoscale mechanics to macroscopic fibres

At DESY’s X-ray light source PETRA III, a team led by Swedish researchers has produced the strongest bio-material that has ever been made. The artifical, but bio-degradable cellulose fibres are stronger than steel and even than dragline spider silk, which is usually considered the strongest bio-based material. The team headed by Daniel Söderberg from the KTH Royal Institute of Technology in Stockholm reports the work in the journal ACS Nano of the American Chemical Society.

The ultrastrong material is made of cellulose nanofibres (CNF), the essential building blocks of wood and other plant life. Using a novel production method, the researchers have successfully transferred the unique mechanical properties of these nanofibres to a macroscopic, lightweight material that could be used as an eco-friendly alternative for plastic in airplanes, cars, furniture and other products. “Our new material even has potential for biomedicine since cellulose is not rejected by your body”, explains Söderberg.

The scientists started with commercially available cellulose nanofibres that are just 2 to 5 nanometres in diameter and up to 700 nanometres long. A nanometre (nm) is a millionth of a millimetre. The nanofibres were suspended in water and fed into a small channel, just one millimetre wide and milled in steel. Through two pairs of perpendicular inflows additional deionized water and water with a low pH-value entered the channel from the sides, squeezing the stream of nanofibres together and accelerating it.

Image: The resulting fibre seen with a scanning electron microscope (SEM).
Credit: Nitesh Mittal, KTH Stockholm

Understanding how alkaline treatment affects bamboo

2018/05/14

In China, bamboo is a symbol of longevity and vitality, able to survive the hardest natural conditions and remain green all year round. In a storm, bamboo stems bend but do not break, representing the qualities of durability, strength, flexibility and resilience¹.

Bamboo is a traditional construction material in Asia. Its strength and flexibility arise from its hollow stems (‘culms’) made from distinct material components. The solid outer shell of the culm is made primarily from longitudinal fibres. A higher density at the outer wall makes it stronger than the inner regions, and results in remarkable stiffness and flexural strength. Running through the centre of bamboo stem are parenchyma cells that store and channel the plant’s nutrients.

At the micro-/nano-scale both the fibres and the matrix contain cellulose nano-fibrils of the same type. However, the structural arrangement of the two materials result in contrasting mechanical properties. Individual fibres may reach a strength of 900 MPa, whilst the matrix can only resist about 50 MPa. There is also a considerable difference in their elastic properties, with the fibres being much stiffer than the matrix.

Bamboo is often treated with alkaline solutions, to modify these properties. Alkaline treatments can turn this rapidly renewable and low-cost resource into soft textiles, and extract fibres to be used in composite materials or as biomass for fuel.

Image: Dr Enrico Salvati on the B16 beamline at Diamond.

World’s fastest water heater

2018/05/142018/05/22

Scientists explore exotic state of liquid with X-ray laser

Scientists have used a powerful X-ray laser to heat water from room temperature to 100,000 degrees Celsius in less than a tenth of a picosecond (millionth of a millionth of a second). The experimental set-up, that can be seen as the world’s fastest water heater, produced an exotic state of water, from which researchers hope to learn more about the peculiar characteristics of Earth’s most important liquid. The observations also have practical use for the probing biological and many other samples with X-ray lasers. The team of Carl Caleman from the Center for Free-Electron Laser Science (CFEL) at DESY and Uppsala University (Sweden) reports its findings in the journal Proceedings of the National Academy of Sciences (PNAS).

The researchers used the X-ray free-electron laser Linac Coherent Light Source LCLS at the SLAC National Accelerator Laboratory in the U.S. to shoot extremely intense and ultra-short flashes of X-rays at a jet of water. “It is certainly not the usual way to boil your water,” said Caleman. “Normally, when you heat water, the molecules will just be shaken stronger and stronger.” On the molecular level, heat is motion – the hotter, the faster the motion of the molecules. This can be achieved, for example, via heat transfer from a stove, or more directly with microwaves that make the water molecules swing back and forth ever faster in step with the electromagnetic field.

Image: After about 70 femtoseconds (quadrillionths of a second) most water molecules have already split into hydrogen (white) and oxygen (red).
Credit: Carl Caleman, DESY/Uppsala University

Respiratory virus study points to likely vaccine target

2018/05/142018/05/21

The work provides a promising route for designing a vaccine effective against a broad range of RSV strains, which cause serious respiratory disease in infants and older adults.

Respiratory syncytial virus (RSV) causes 118,000 deaths in young children each year worldwide and 57,000 hospitalizations of children each year in the United States alone. Attempts to develop a vaccine—at first based on inoculations with inactivated virus, and then targeting a key viral surface protein (RSV F)—have failed. Recent studies, however, suggest that a second viral surface protein (RSV G) is a promising target.

In one earlier study, elevated concentrations of antibodies targeting both RSV F and RSV G were associated with lower clinical disease severity scores, despite a substantially lower absolute abundance of anti-G antibodies. Another study found that higher levels of maternal anti-G antibodies correlated with less severe disease in infants (up to 4-6 months of age), even though anti-G antibodies were again found in lower concentrations.

While the RSV F surface protein allows the virus to enter a host cell, RSV G is what allows the virus to stick to lung cells and distort immune responses. This disruption of the immune response by RSV G might explain why vaccines based on RSV F have failed. Thus, a protective antibody response that blocks RSV G activity could be more effective, but scientists didn’t know how antibodies target RSV G at the molecular level.

>Read more on the ALS website.

Image: Stanislav Fedechkin and Rebecca DuBois.
Credit: C. Lagattuta/UC Santa Cruz

Spin and charge frozen by strain

2018/05/092018/05/10

In the development of next-generation microelectronics, a great deal of attention has been given to the use of epitaxy (the deposition of a crystalline overlayer on a crystalline substrate) to tailor the properties of materials to suit particular applications. Correlated electron systems provide an excellent platform for the development of new microelectronic devices due to the presence of multiple competing ground states of similar energy. In some cases, strain can drive these systems between two or more such states, resulting in phase transitions and dramatic changes in the properties of the material. Often, the specific mechanism by which strain accomplishes such a feat is unknown. This was precisely the case in lanthanum cobaltite, LaCoO₃, which undergoes a strain-induced transition from paramagnet to ferromagnet, until a recent study carried out at the U.S. Department of Energy’s Advanced Photon Source (APS) revealed the intriguing microscopic phenomena at work in this system. These phenomena may play a role in spin-state and magnetic-phase transitions, regardless of stimulus, in many other correlated systems.

Lanthanum cobaltite is a perovskite, which means the structure can be thought of as made up of distorted cubes with cobalt at the cube centers, oxygen at the cube faces, and lanthanum at the cube corners. The cobalt ions have a nominal 3+ valence, meaning they lose three electrons to the neighboring oxygen ions. Bulk LaCoO₃ is paramagnetic (that is, having a net magnetization only in the presence of an externally applied magnetic field) above 110 Kelvin, and non-magnetic below that temperature. In its ground state, all the electrons on a given cobalt ion are paired, meaning their magnetic spins cancel each other out. These are so-called low-spin (LS) Co³⁺ ions, and when all of the cobalt ions are in this form, LaCoO₃ is non-magnetic.

Image: Upper left: Resonant x-ray scattering at the cobalt K-edge. Inversion of the spectra at the reflections shown indicates the presence of charge order. Upper right: X-ray diffraction reciprocal space maps at the (002) and (003) reflection indicating the high epitaxial quality of the films. The satellite peaks result from lattice modulations associated with the reduced symmetry in the film. Lower left: Schematic crystal structure of epitaxial LaCoO3 showing the arrangement of cobalt sites with different charge and spin. The circulated charge transfer from oxygen to the different cobalt sites is also shown. Lower right: Calculated total energy as a function of the difference between the in-plane Co-O bond lengths of HS and LS cobalt ions (∆rCo-O).

X-ray laser opens new view on Alzheimer proteins

2018/05/092018/05/09

Graphene enables structural analysis of naturally occurring amyloids

A new experimental method permits the X-ray analysis of amyloids, a class of large, filamentous biomolecules which are an important hallmark of diseases such as Alzheimer’s and Parkinson’s. An international team of researchers headed by DESY scientists has used a powerful X-ray laser to gain insights into the structure of different amyloid samples. The X-ray scattering from amyloid fibrils give patterns somewhat similar to those obtained by Rosalind Franklin from DNA in 1952, which led to the discovery of the well-known structure, the double helix. The X-ray laser, trillions of times more intense than Franklin’s X-ray tube, opens up the ability to examine individual amyloid fibrils, the constituents of amyloid filaments. With such powerful X-ray beams any extraneous material can overwhelm the signal from the invisibly small fibril sample. Ultrathin carbon film – graphene – solved this problem to allow extremely sensitive patterns to be recorded. This marks an important step towards studying individual molecules using X-ray lasers, a goal that structural biologists have long been pursuing. The scientists present their new technique in the journal Nature Communications.

Amyloids are long, ordered strands of proteins which consist of thousands of identical subunits. While amyloids are believed to play a major role in the development of neurodegenerative diseases, recently more and more functional amyloid forms have been identified. “The ‘feel-good hormone’ endorphin, for example, can form amyloid fibrils in the pituitary gland. They dissolve into individual molecules when the acidity of their surroundings changes, after which these molecules can fulfil their purpose in the body,” explains DESY’s Carolin Seuring, a scientist at the Center for Free-Electron Laser Science (CFEL) and the principal author of the paper. “Other amyloid proteins, such as those found in post-mortem brains of patients suffering from Alzheimer’s, accumulate as amyloid fibrils in the brain, and cannot be broken down and therefore impair brain function in the long term.”

>Read more on the DESY website

Image: On the ultra-thin, extremely regular layer of graphene, the fibrils align themselves in parallel in large domains. The intense X-ray light from the X-rax free-electron laser LCLS at the SLAC National Accelerator Center enabled the researchers to gain partial information about the fibril structure from ensembles of just a few fibrils.
Credit: Greg Stewart/SLAC National Accelerator Laboratory

The proteins that bind

2018/05/082018/05/09

Researchers reveal the structure of a protein that helps bacteria aggregate

Serine-rich repeat proteins (SRRPs), which help bacteria attach to surfaces, have been structurally characterised in pathogenic bacteria but not in beneficial bacteria such as those present in the gut. Dr Nathalie Juge’s team at the Quadram Institute Bioscience has previously identified SRRP as a main adhesin in Lactobacillus reuteri strains from pigs and mice. Now, together with colleagues at the University of East Anglia, they have described the structure and activity of the binding region of L. reuteri SRRPs in a paper published in PNAS. Using the Macromolecular Crystallography beamlines (I03 and I04) at Diamond Light Source, they discovered that the structure of these proteins is unique among characterised SRRPs and is surprisingly similar to pectin degrading enzymes. Molecular simulations and binding experiments revealed a pH-dependent binding to pectin and to proteins from the epithelium known as mucins. Altogether, these findings shed light on the activity of a key protein in these bacteria and may help guide the development of more targeted probiotic interventions.

Figure: (Left) Cartoon representation of crystal structures of the binding region of SRRP53608. (Right) Cartoon representation of crystal structures of the binding region of SRRP100-23. The N-terminus is shown with blue balls and the C-terminus is shown with red balls.

Record number of visitors at ALBA Open Day

2018/05/072018/05/10

The ALBA Open Day, held last Saturday 5 May, received 2,321 visitors who could discover how this scientific facility works and what its main applications are.

Despite again this year the rain was present in its seventh celebration, the ALBA Open Day welcomed a record number of visitors: 2,321 people.

From 9:00 a.m. to 7:00 p.m., more than 100 volunteers, members of the ALBA staff, showed the facilities to the attendees and explained them the operation and characteristics of the electron accelerators’ complex, aimed at producing synchrotron light for analysing the properties of matter.

The event followed a free itinerary where visitors were able to see the devices where the electrons pass through or those used for manipulating the synchrotron light, to participate in fun demonstrations to know more about concepts like vacuum or pressure, microscopy or spectroscopy. New this year, the ALBA Open Day hosted an exhibition to highlight the role of women in science as well as an art exhibition on pinhole photography and solarigraphy, images taken with cans and that collect the trajectory of Sun, respectively. The area devoted to the youngest was also very crowded with experiments and activities for them. Besides, three conferences were given about particle accelerators (Caterina Biscari, director of ALBA), how synchrotron light is generated (Pep Campmany, researcher responsible of the insertion devices section) and why a synchrotron facility is a useful tool (Miguel Ángel García Aranda, scientific director).

Sunshine, science and seed bombs at European XFEL’s first open day in Schenefeld

2018/05/052018/05/09

More than 2500 visitors to event in Schenefeld

On Saturday, under sunny spring skies, more than 2500 visitors attended European XFEL’s first Open Day on the campus in Schenefeld. Guests of all ages enjoyed a diverse and varied program of activities, talks, exhibitions and tours, giving an insight into the work, staff and community of the new research centre.

Schleswig Holsteins Minister for Science Karin Prien, Schenefeld Mayor Christiane Küchenhof and European XFEL Managing Director Prof. Robert Feidenhans’l officially opened the event just after midday. “It’s great to see so much interest in our facility!” said Feidenhans’l. “We are very proud to be able to present our facility. More than 150 staff members of European XFEL, as well as our campus partners have worked really hard in preparation for this premiere. Seeing so much enthusiasm for science among people of all age groups is an additional boost for our work during the next few weeks and months. I thank all staff member and campus partners for their support that has made this day possible.” Later Hamburg’s second mayor and science minister Katharina Fegebank also visited the event and greeting the visitors.

>Read more on the European XFEL website

Image: Left to right: Schenefeld Mayor Christiane Küchenhof, European XFEL Administrative Director Nicole Elleuche, Schleswig-Holstein Science Minister Karin Prien, and European XFEL Managing Director Prof. Robert Feidenhans’l during the visit to the tunnel.
Credit: European XFEL