Enlightening yellow in art

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 19th 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.

The 2018 Julian David Baumert Ph.D. Thesis Award

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.

>Read more on the NSLSI-II at Brookhaven National Laboratory website

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.

Probing tumour interiors

X-ray fluorescence mapping to measure tumour penetration by a novel anticancer agent.

A new anticancer agent developed by the University of Warwick has been studied using microfocus synchrotron X-ray fluorescence (SXRF) at I18 at Diamond Light Source. As described in The Journal of Inorganic Biochemistry, researchers saw that the drug penetrated ovarian cancer cell spheroids and the distribution of zinc and calcium was perturbed.  

Platinum-based chemotherapy agents are used to treat many cancer patients, but some can develop resistance to them. To address this issue, scientists from the University of Warwick sought to employ alternative precious metals. They developed an osmium-based agent, known as FY26, which exhibits high potency against a range of cancer cell lines. To unlock the potential of this novel agent and to test its efficacy and safety in clinical trials, the team need to fully understand its mechanism of action.

To explore how FY26 behaves in tumours, the team grew ovarian cancer spheroids and used SXRF at I18 to probe the depth of penetration of the drug. They noted that FY26 could enter the cores of the spheroids, which is critical for its activity and very encouraging for the future of the drug. SXRF also enabled them to probe other metals within the cells, which showed that the distribution of zinc and calcium was altered, providing new insights into the mechanism of FY26-induced cell death.

>Read more on the Diamond Light Source website

Figure: (extract) A) Structure of FY26and related complexes, [(ŋ6-p-cym)Os(Azpy-NMe2)X]+. B) Bright field images and SXRF elemental maps of Os, Ca and Zn in A2780 human ovarian carcinoma spheroid sections (500 nm thick) treated with 0.7 µM FY26(½ IC50) for 0 or 48 h. Raster scan: 2×2 µm2 step size, 1 s dwell time. Scale bar 100 µm. Calibration bar in ng mm-2. Yellow squares in bright field images indicate areas of the spheroid studied using SXRF. Red areas in SXRF elemental maps indicate the limits of the spheroids. C) Average Os content (in ng mm-2) as a function of distance from A2780 3D spheroid surface, after treatment for 16 h (green), 24 h (blue) or 48 h (red) with 0.7 µM FY26. 

The power of radio!

A century after the invention of radio, the oscillating electric fields initially generated for communication now perform a fundamental function in all accelerators.

Instead of being broadcast to the world, radiofrequency (RF) energy at Diamond is trapped in resonating metal cavities to generate the electric fields that bring Diamond’s electrons up to speed.

The journey of an electron from source to storage ring is a tale of high power, split-second timing and frankly terrifying voltages. It begins in the linac gun where energetic, hot electrons are sucked away from a metal cathode by 90,000 volts and directed into the linear accelerator, or linac. The electrons travel down the linac together with precisely timed 16 megawatt blasts of microwaves generated by klystron amplifiers that themselves operate at pulsed voltages in excess of 200,000 volts. Electrons are accelerated towards the speed of light in the linac and then injected into the booster synchrotron where they complete many orbits over a tenth of a second.

>Read more on the Diamond Light Source website

Image: The linac, with the gun at the far end and the accelerating structures coming towards us.

A surprising twist on skyrmions

Magnetic tomography has been used to reconstruct a tornado-like 3D magnetic skyrmion structure.

Vortex structures are common in nature, reaching from swirls in our morning coffee to spiral galaxies in the universe. Vortices are been best known from fluid dynamics. Take the example of a tornado. Air circulates around an axis, forming a swirl, and once formed, the twisted air parcels can move, deform, and interact with their environment without disintegrating. A skyrmion is the magnetic version of a tornado which is obtained by replacing the air parcels that make up the tornado by magnetic spins, and by scaling the system down to the nanometre scale. Once formed, the ensemble of twisted spins can also move, deform, and interact with their environment without breaking up ‒ the ideal property for information carriers for memory and logic devices.

What makes a tornado stable is not only coming from its twist, but also due to its three-dimensional properties, i.e., the wind current has extra twist along the column of turbulent flow. This leads to a tight bundling of the vortex sheets at different heights along the tornado column. Similarly, such a 3D structure can also occur in magnetic skyrmions, guaranteeing their topological stability. Up to now, skyrmions have been most commonly treated as two-dimensional objects, and their exciting tornado-like structure remained unexplored. In fact, the 3D characterization of magnetic structures is a rather challenging task. A team of researchers, led by the University of Oxford and Diamond Light Source, have used the energy-dependence of resonant elastic X-ray scattering (REXS) on beamline I10 at Diamond to measure the microscopic depth dependence of ‘skyrmion tornados’ in Cu2OSeO3. In their work, published in Proceedings of the National Academy of Sciences, they reveal a continuous change from Néel-type winding at the surface to Bloch-type winding in the bulk with increasing depth. This not only demonstrates the power of REXS for microscopic studies of surface-induced reconstructions of magnetic order, but also reveals the hidden energetics that makes magnetic skyrmions such a stable state – a crucial finding for skyrmion device engineering.

>Read more on the Diamond Light Source website

Figure: Illustration of a ‘Skyrmion tornado’. The skyrmion order changes from Néel-type at the surface to Bloch-type deeper in the sample. On the right hand side, the corresponding stereographic projections of these two boundary skyrmion patterns are shown.

Helmholtz Association supports ATHENA

ATHENA (“Accelerator Technology HElmholtz iNfrAstructure”) is a new research and development platform focusing on accelerator technologies and drawing on the resources of all six Helmholtz accelerator institutions (DESY, Jülich Research Centre, Helmholtz Centre Berlin, Helmholtz Centre Dresden-Rossendorf HZDR, KIT and GSI with the Helmholtz Institute of Jena). The Helmholtz Association has now decided to pay almost 30 million euros towards ATHENA as a strategic development project. “This decision demonstrates the Helmholtz Association’s strong commitment to developing and supplying ground-breaking new accelerator technologies for solving the future challenges faced by society,” says Helmut Dosch, who is the Chairman of DESY’s Board of Directors and also the spokesperson for the Helmholtz Association’s research division Matter.

Together, these centres want to set up two German flagship projects in accelerator research based on innovative plasma-based particle accelerators and ultramodern laser technology: an electron accelerator at DESY in Hamburg and a hadron accelerator at HZDR. At both facilities, a range of different fields of application are to be developed, ranging from a compact free-electron laser, through novel medical uses to new applications in nuclear and particle physics. As soon as they have reached the necessary level of maturity to be put to practical use in a particular area, new compact devices could be built for use in other Helmholtz centres, as well as in universities and hospitals.

>Read more on the Bessy II at HZB website or the DESY website

Tripling the energy storage of lithium-ion batteries

Scientists have synthesized a new cathode material from iron fluoride that surpasses the capacity limits of traditional lithium-ion batteries.

As the demand for smartphones, electric vehicles, and renewable energy continues to rise, scientists are searching for ways to improve lithium-ion batteries—the most common type of battery found in home electronics and a promising solution for grid-scale energy storage. Increasing the energy density of lithium-ion batteries could facilitate the development of advanced technologies with long-lasting batteries, as well as the widespread use of wind and solar energy. Now, researchers have made significant progress toward achieving that goal.

A collaboration led by scientists at the University of Maryland (UMD), the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory, and the U.S. Army Research Lab have developed and studied a new cathode material that could triple the energy density of lithium-ion battery electrodes. Their research was published on June 13 in Nature Communications.

>Read more on the NSLS-II at Brookhaven National Lab website

Image: Brookhaven scientists are shown at the Center for Functional Nanomaterials. Pictured from left to right are: (top row) Jianming Bai, Seongmin Bak, and Sooyeon Hwang; (bottom row) Dong Su and Enyuan Hu.

Canadian researchers unlock how seaweed is digested

Cattle on the Prairies are hundreds of kilometres from the coast and yet it’s possible that seaweed could make its way into their diet as an additive.

“Seaweed is an incredible opportunity. It is a sustainable feedstock. It grows rapidly, it doesn’t require arable land or fresh water to grow,” said Wade Abbott, research scientist at Agriculture and Agi-Food Canada’s Lethbridge Research and Development Centre.

It may seem like a leap to go from the human gut to that of cattle, but Abbott explained that by understanding the human gut microbiome, or microorganisms, and the microbiome’s ability to use the sugars found in seaweed in its symbiotic relationship with the host, he sees potential to expand what is now a limited use of algae products.

>Read more on the Canadian Light Source website

Image: Culturing gut bacteria in the lab (shown in these test tubes) allows researchers ‎to determine which genes in the genomes of bacteria are activated and discover new enzymes that digest rare substrates like agarose.
Credit: Wade Abbott

Insulator metal transition at the nanoscale

An international team of researchers has been able to probe the insulator-conductor phase transition of materials at the nanoscale resolution. This is one of the first results of MaReS endstation of BOREAS beamline.

Controlling the flow of electrons within circuits is how electronic devices work. This is achieved through the appropriate choice of materials. Metals allow electrons to flow freely and insulators prevent conduction. In general, the electrical properties of a material are determined when the material is fabricated and cannot be changed afterwards without changing the material. However, there are materials that can exhibit metal or insulator behaviour depending on their temperature. Being able switch their properties, these materials could lead to a new generation of electronic devices.

Vanadium Dioxide (VO2) is one such material. It can switch from an insulating phase to a metallic phase just above room temperature, a feature exploited already for sensors. However, the reason why the properties of this material change so dramatically has been a matter of scientific debate for over 50 years.

One of the challenges in understanding why and how this switch occurs is due to a process called phase separation. The insulator-metal phase transition is similar to the ice to liquid transition in water. When ice melts, both liquid and solid water can coexist in separate regions. Similarly, in VO2, insulating and metallic regions of the material can be coexisting at the same time during the transition. But unlike water, where the different regions are often large enough to see with the naked eye, in VOthis separation occurs on the nanoscale and it is thus challenging to observe. As a result, it has been hard to know if the true properties of each phase, or the mixture of both phases, are being measured.

>Read more on the ALBA Synchrotron website

Image: (extract, original here) reconstructed holograms at the vanadium and oxygen edges (518, 529, and 530.5 eV) used to encode the intensities of the three color channels of an RGB (red, green, blue) image. At 330 K, an increase in intensity of the green channel, which probes the metallic rutile phase (R) through the d∥ state, is observed in small regions. As the sample is heated further, it becomes increasingly clear that the blue channel, which probes a intermediate insulating M2 phase, also changes but in different regions. At 334 K, three distinct regions can be observed corresponding to the insulating monoclinic M1, M2, and metallic R phases. As the temperature increases, the R phase dominates. The circular field of view is 2 μm in diameter. (taken from Vidas et al, Nanoletters, 2018).