The shape of snow: New insights could help climate models

Scientists from the Institut des Géosciences de l’Environnement of Grenoble, the Centre d’Etudes de la Neige and the Groupe de Météorologie Expérimentale et Instrumentale have developed a new approach for measuring the interaction between snow and sunlight. This methodology is important to improve the accuracy of climate models. They did X-ray tomography experiments at ESRF ID19 beamline. The results are published in Nature Communications.

Once deposited on the ground, snow is a material composed of air and ice crystals, whose shape and arrangement vary greatly at the micrometre scale. This is known as the microstructure of snow. This “skeleton” of ice and air governs the propagation of light within the snowpack through optical phenomena such as refraction and internal reflections in the ice phase.

However, despite its extreme complexity and irregularity, natural snow is still represented in a simplistic manner in almost all optical models, including those implemented in climate models. These models typically depict snow as a collection of ice particles with perfect geometric shapes, mainly spheres. Among the many implications for the energy balance of snow, this simplification leads to significant uncertainties in climate modelling, with potential impacts of up to 1.2°C on global air temperature.

In this new study, the authors from the Institut des Géosciences de l’Environnement of Grenoble (IGE / CNRS – INRAE – IRD – UGA – Grenoble INP-UGA), the Centre d’Etudes de la Neige (CEN / CNRM / Météo-France – CNRS) and the Groupe de Météorologie Expérimentale et Instrumentale (GMEI / CNRM / Météo-France – CNRS) have accurately simulated the light propagation in a collection of 3D images of snow microstructure obtained by X-ray tomography, using a ray-tracing model. Very different snow types were investigated, from fresh snow (PP) to refrozen melt-freeze forms (MF). Some images were obtained at the 3SR-Lab. Several snow microstructures required higher resolution and were acquired at ESRF beamline ID19.

Read more on the ESRF website

Image: Snow microstructure: This is what fresh snow looks like at the micrometre scale

Seeing more deeply into nanomaterials

New 3D imaging tool reveals engineered and self-assembled nanoparticle lattices with highest resolution yet—7nm—about 1/100,000 of the width of a human hair

From designing new biomaterials to novel photonic devices, new materials built through a process called bottom-up nanofabrication, or self-assembly, are opening up pathways to new technologies with properties tuned at the nanoscale. However, to fully unlock the potential of these new materials, researchers need to “see” into their tiny creations so that they can control the design and fabrication in order to enable the material’s desired properties.

This has been a complex challenge that researchers from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory and Columbia University have overcome for the first time, imaging the inside of a novel material self-assembled from nanoparticles with seven nanometer resolution, about 1/100,000 of the width of a human hair. In a new paper published on April 7, 2022 in Science, the researchers showcase the power of their new high-resolution x-ray imaging technique to reveal the inner structure of the nanomaterial. 

The team designed the new nanomaterial using DNA as a programmable construction material, which enables them to create novel engineered materials for catalysis, optics, and extreme environments. During the creation process of these materials, the different building blocks made of DNA and nanoparticles shift into place on their own based on a defined “blueprint”—called a template—designed by the researchers. However, to image and exploit these tiny structures with x-rays, they needed to convert them into inorganic materials that could withstand x-rays while providing useful functionality. For the first time, the researchers could see the details, including the imperfections within their newly arranged nanomaterials.

Read more on the BNL website

Image: An artist’s impression of how the researchers used x-ray tomography as a magnifying lens to see into the inner structure of nanomaterials

The reign of the dinosaurs ended in spring

The asteroid that killed nearly all dinosaurs struck Earth during springtime.  An international team of scientists from the Vrije Universiteit (VU) Amsterdam (The Netherlands), Uppsala University (Sweden), Vrije Universiteit Brussel (Belgium) and the ESRF, the European Synchrotron (France), have determined when the meteorite crashed onto the Earth, after analysing the remains of fish that died just after the impact. Their results are published in the journal Nature today.

Around 66 million years ago, the Chicxulub meteorite crashed into the Earth, in what today is the Yucatán peninsula in Mexico, marking the demise of dinosaurs and end of the Cretaceous period. This mass extinction still puzzles scientists today, as it was one of the most selective in the history of life: all non-avian dinosaurs, pterosaurs, ammonites, and most marine reptiles disappeared, whilst mammals, birds, crocodiles, and turtles survived.

A team of scientists from the Vrije Universiteit, Uppsala University, and the ESRF have now shed light on the circumstances surrounding the diverse extinction across the different groups. The answers came from the bones of fish that died moments after the meteorite struck.

Read more on the ESRF website

Image: Melanie During points to a section of a Paddlefish dentary showing high bone cell density (i.e. summer)

Credit: Melanie During

Time to fly! One scientist’s story of being inspired and inspiring others

Shiva Shirani is from Iran and is currently completing a PhD at the University of Malaga. Shiva’s research area is Synchrotron X-ray imaging applied to cementitious material with the goal to decrease our CO2 footprint and protect the planet. Many participants in our #LightSourceSelfies campaign have talked about the need to overcome setbacks and failure. There will always be challenges but success will come. Shiva’s research ideas led to her being granted an OPEN SESAME Fellowship to become a young scientific visitor at ID19 tomography beamline at the ESRF. But prior to this, there were setbacks. Shiva’s story, which she tells with honestly and passion, charts these setbacks and how she eventually found people who believed in her ideas. People who helped Shiva find her “two wings to fly”.

One of these people was the late Claudio Ferrero, one of Shiva’s supervisors at the ESRF. Claudio recognised the unique way that Shiva shares her passion for science with the world via Twitter and Instagram and encouraged her to continue this inspirational science communication. In the early stages of planning the #LightSourceSelfies campaign, and SESAME recognised this too! We were delighted when Shiva agreed to participate in our campaign and we are very grateful to the ESRF who subsequently helped Shiva with the filming.

Here we present Shiva Shirani’s #LightSourceSelfie!

SESAME’s #LightSourceSelfie featuring Shiva Shirani

How some plants evolved to depend on fire for survival

Researchers based at Monash University and the Swedish Museum of Natural History have pioneered the use of nuclear imaging techniques at ANSTO’s Australian Centre for Neutron Scattering to resolve long-standing gaps in knowledge of the evolution of plants, including Australian natives, that adapted to depend on fires.

Their work has highlighted the key role of wildfires* in the evolution of floral ecosystems.

Dr Chris Mays, a Postdoctoral Researcher at the Swedish Museum of Natural History and Research Affiliate at Monash University, has used fossils of plant reproductive structures, like pine cones, to show how they have adapted to fire.

Plants are known to have adapted during two pivotal intervals in their evolutionary history: a mass extinction event in the end Permian period (252 million years ago) and the rise of the flowering plants during the mid-Cretaceous hothouse period  (120–95 million years ago).

“These extreme warming periods were evolutionary ‘bottlenecks’, through which only fire-adapted plants survived. The evolutionary legacy is all around us in Australia, where a huge proportion of the plants today have fire-adaptive traits,” said Mays.

Using neutron tomography on Dingo, the researchers were able to virtually extract images of amber from within fossils and differentiate plant tissues.

“Neutron tomography is an ideal method for non-destructive, three-dimensional imaging of organically preserved, or ‘coalified’, fossil plants. These are the most common types of plant fossils in the rock record,” said Mays.

Because neutrons can easily penetrate through dense sediments, they can be used to see details of extremely fragile fossils, like those of coalified plants, without the need for meticulous extraction. This minimalist approach to fossil preparation ensures that such delicate fossils remain well-preserved in their protective sediments.

The plant fossils are hydrogen-rich, which means they stand out in contrast to the surrounding rock matrix when imaged with high-resolution neutron tomography.

“Neutrons can successfully differentiate fossil plant tissue that is compositionally similar, where other techniques routinely fail,” said Mays.

X-ray tomography on the Imaging and Medical beamline at the Australian Synchrotron was also undertaken to supplement the neutron investigations.

Read more on the ANSTO website

Image: Dr Maggie-Anne Harvey (left) and Dr Andrew Langendam preparing fossil plant specimens on Dingo

Credit: ANSTO

X-ray tomography as a new tool to analyse the voids in RRP Nb3Sn wires

Scientists have developed a new tool to investigate the internal features of Nb3Sn superconducting wires, combining X-ray tomographic data acquired at beamline ID19 with an unsupervised machine-learning algorithm. The method provides new insights for enhancing wire performance.

Interest in niobium-tin (Nb3Sn) as a material for superconducting wires has recently been renewed because this material has been selected to replace niobium-titanium as the next step in accelerator magnet technology [1]. The design of these magnets relies on the availability of advanced Nb3Sn wires capable of withstanding extreme mechanical and thermal loads. The Restacked Rod Process (RRP) is considered the most promising technology to produce Nb3Sn wires at industrial scale for future accelerator magnets.

Nb3Sn is a brittle superconducting compound that cannot be drawn directly in the form of a wire. Instead, ductile precursor components are embedded in a copper matrix, drawn, brought to the final shape and then heat-treated, so that Nb3Sn forms in a reactive diffusion process. The result is a composite wire with several Nb3Sn sub-elements surrounded by copper. However, the diffusion process can lead to voids, which can play a role in the electro-mechanical and thermal behaviour of the wire. A team of scientists have developed a novel, non-destructive and non-invasive method to investigate the voids in high-performance RRP Nb3Sn superconducting wires, combining X-ray microtomography data at beamline ID19 with an unsupervised machine-learning algorithm, with a view to providing new insights into the development of these wires.

Read more on the ESRF website

Image:Fig. 1: a) 3D cross-section of a RRP Nb3Sn wire: Nb3Sn sub-elements (red), sub-element voids (light blue), copper voids (white), copper matrix (grey). b) Longitudinal cross-section of a void generated by Sn diffusion due to a leak in the sub-element. The void is highlighted in red inside the sub-element and in blue in the copper matrix, showing the sub-element failure point.

First glimpse of intricate details of Little Foot’s life

In June 2019, an international team brought the complete skull of the 3.67-million-year-old ‘Little Foot’ Australopithecus skeleton, from South Africa to the UK and achieved unprecedented imaging resolution of its bony structures and dentition in an X-ray synchrotron-based investigation at Diamond. The X-ray work is highlighted in a new paper in e-Life, published today focusing on the inner craniodental features of ‘Little Foot’. The remarkable completeness and great age of the ‘Little Foot’ skeleton makes it a crucially important specimen in human origins research and a prime candidate for exploring human evolution through high-resolution virtual analysis.

To recover the smallest possible details from a fairly large and very fragile fossil, the team decided to image the skull using synchrotron X-ray micro computed tomography at the I12 beamline at Diamond, revealing new information about human evolution and origins. This paper outlines preliminary results of the X-ray synchrotron-based investigation of the dentition and bones of the skull (i.e., cranial vault and mandible).

Read more on the Diamond website

Image: Fossil skull in Diamond’s beamline I12

Credit: Diamond Light Source

Graphite electrodes for rechargeable batteries investigated

Rechargeable graphite dual ion batteries are inexpensive and powerful.

A team of the Technical University of Berlin has investigated at the EDDI Beamline of BESSY II how the morphology of the graphite electrodes changes reversibly during cycling (operando).

The 3D X-ray tomography images combined with simultaneous diffraction now allow a precise evaluation of the processes, especially of changes in the volume of the electrodes. This can help to further optimise graphite electrodes.

Read more on the HZB website

Image: The tomogram during the charging process shows the spatially resolved changes in the graphite electrode thickness of a rechargeable aluminium ion battery in a discharged and charged state.

Credit: © HZB