Diamond Concise Annual Review 2019/20

D I A M O N D L I G H T S O U R C E A N N U A L R E V I E W 2 0 1 9 / 2 0 D I A M O N D L I G H T S O U R C E A N N U A L R E V I E W 2 0 1 9 / 2 0 20 21 8 1 9 T he Imaging and Microscopy Group brings together eight experimental facilities (beamlines I08, J08, DIAD, I12, I13-1, I13-2, I14 and ePSIC) which use electrons and X-rays to image samples under different experimental conditions across a diverse range of length scales and time scales. Different contrast mechanisms allow for imaging of sample properties such as elemental composition, density and structure. This ability to extract image sample properties inminute detail lends itself to a wide range of scientific areas, from chemistry and catalysis to environmental science, materials science, biology, medicine and cultural heritage. The Scanning X-ray Microscopy beamline (I08) and the DIAD (Dual Imaging And Diffraction) beamline are an exciting addition to the group. They are undergoing final commissioning and testing andmay be available to users in late 2020. Studies from the group this year included discovering the world’s oldest fungi, optimising arc welding techniques and earlier detection of osteoarthritis. Identifying the oldest fungi Ancient fungi are thought to have been crucial symbiotic partners of the earliest land plants due to their ability to facilitate nutrient uptake through their network of filaments in the soil. However, the timing of this major evolutionary transition is largely unknown because of the scarcity and ambiguous nature of the Precambrian fossil record for fungi. Until now, the oldest confirmed mushroom fossil was 460 million years old and identification has been based on the size and shape of fossils.This has hindered understanding of the early evolution of fungi and the beginnings of more complex life forms. A team of international researchers used Diamond synchrotron techniques to investigate fossilised filamentous networks in rocks formed between 715 and 810 million years ago. Using X-ray absorption near-edge spectroscopy (XANES) on beamline I08, they investigated ultrathin sections of the fossilised filaments to identify traces of chitin, a constituent of fungal cell walls. They combined these results with complementary μFTIR (Fourier Transformed InfraRed) spectroscopy on beamline B22. This research shows that fungi were already present on Earth between 715 and 810 million years ago, almost 300 million years earlier than previously thought. This innovative synchrotron research provides new insights into evolutionary processes and show that these fungi could have participated in the establishment of the first land plants. Bonneville S et al . doi: 10.1126/sciadv.aax7599 Optimising arc welding techniques In fusion welding and additive manufacturing, metal is melted to form a molten pool that, when solid, can form high integrity products for cars, ships and other large metallic structures. Correct control of the melt pool is essential in manufacturing processes to avoid catastrophic failures, but, until now direct experimental observation of flow evolution has been challenging. For the first time an international research team was able to achieve direct imaging of melt pool flow dynamics during arc welding of steel under realistic manufacturing conditions using beamline I12. The results showed that when the temperature-dependent surface tension coefficient is negative, bulk turbulence is the main flow mechanism and the critical velocity for surface turbulence is below the limits identified in previous theoretical studies. When the alloy has a positive temperature-dependent surface tension coefficient, surface turbulence occurs and damaging oxides can be trapped within the subsequent solid as a result of higher flow velocities. The study provides new ways to optimise arc welding and wire arc additive manufacturing by controlling internal melt flow through adjusting surface-active elements such as sulphur. Aucott L et al . doi: 10.1038/s41467-018-07900-9 Early detection of osteoarthritis Therearecurrentlynoeffectivemethodsfortheearlydetectionofosteoarthritis (OA). In addition, the way that early-stage OA affects the shape and mechanical behaviour of different joint tissues is not well understood. Researchers from the UK and USA have used beamline I13-2 at Diamond to take the first time-resolved 3D images of different tissues with cellular-level resolution while the joint was under lifelike loading. These images were then analysed to resolve the strains and displacements within the tissue with 100 nm resolution. The team used a combination of three key advances (low-dose pink phase contrast imaging, a unique nano-precision loading device and bespoke digital volume correlation analysis software) to characterise how the articular cartilage adapts to spread load during the early stages of OA. This new technique may be used in the future to determine the efficacy of new treatments for OA at very early stages. Madi K et al . doi:10.1038/s41551-019-0477-1 Imaging andMicroscopy Group