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Abstract: Determination of mineral texture and diagenetic features in mudstones is crucial to reveal the history of their pore systems and provides key information to predict their future sealing ability, reactivity and storage capacity for sequestered CO2, hydrogen storage or nuclear waste disposal. To understand the spatial transport and storage of fluids, it is necessary to map the distribution of minerals and fractures in three dimensions (3D). This study proposes a novel, multi-scale three-dimensional (3D) imaging method, i.e., a combination of synchrotron- sourced micro- x-ray tomography and lab- sourced nano-tomography, to investigate the sedimentology and diagenetic features of the Bowland Shale, one of the most volumetrically important mudstone-dominated systems in the UK. Diagenetic minerals have been identified and characterised, including pyrite, calcite, kaolinite, illite, chlorite, dolomite, ankerite and authigenic quartz (micro-sized quartz and quartz overgrowths). Multi-scale 3D images provide detailed information about dolomite-ankerite zonation and carbonate dissolution pores. These features cannot be observed or quantified by conventional 2D methods, and they have not been reported in this subject area before. Using these results, potential reactions during carbon storage and other subsurface storage applications are predicted.

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Abstract: Local coexistence of bees has been explained by flower resource partitioning, but coexisting bumblebee species often have strongly overlapping diets. We investigated if light microhabitat niche separation, underpinned by visual traits, could serve as an alternative mechanism underlying local coexistence of bumblebee species. To this end, we focused on a homogeneous flower resource—bilberry—in a heterogeneous light environment—hemi-boreal forests. We found that bumblebee communities segregated along a gradient of light intensity. The community-weighted mean of the eye parameter—a metric measuring the compromise between light sensitivity and visual resolution—decreased with light intensity, showing a higher investment in light sensitivity of communities observed in darker conditions. This pattern was consistent at the species level. In general, species with higher eye parameter (larger investment in light sensitivity) foraged in dimmer light than those with a lower eye parameter (higher investment in visual resolution). Moreover, species realized niche optimum was linearly related to their eye parameter. These results suggest microhabitat niche partitioning to be a potential mechanism underpinning bumblebee species coexistence. This study highlights the importance of considering sensory traits when studying pollinator habitat use and their ability to cope with changing environments.

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Abstract: Deformation bands, or tabular zones of localised strain, are a common manifestation of deformation in upper crustal sedimentary rocks. Any mining or energy-related engineering applications must consider the possibility of reactivating these pre-existing failure planes because doing so can cause seismicity and compartmentalise the reservoir. However, there has only been a small amount of research done on laboratory-induced deformation in rocks with natural deformation features. On a low porosity bioclastic calcarenite from the Cotiella Basin, Spanish Pyrenees, our current experimental work aims to capture, for the first time to our knowledge, the dominant failure mechanisms during the reactivation of natural deformation bands oriented at different angles to the principal stress direction. At the I12-JEEP beamline at the synchrotron facility of Diamond Light Source, UK, we carried out triaxial compression experiments using a modified version of the Mjolnir cell used by Cartwright-Taylor et al., (2022) to examine how these highly heterogeneous rocks respond to additional mechanical deformation. During the deformation experiments, 4D (time and space) x-ray tomography images (8 m voxel size resolution) were acquired. We tested confining pressures between 10 MPa and 30 MPa. The mechanical data demonstrate that the existence of natural deformation features within the tested samples weakens the material. For instance, solid samples of the host rock subjected to the same confining pressures had higher peak differential stresses. Additionally, our findings demonstrate that new deformation bands form as their angle, θ, to σ1 increases, while the reactivation of pre-exiting deformation bands in this low porosity carbonate only occurs for dipping angles close to 70o. The spatio-temporal relationships between the naturally occurring and laboratory-induced deformation bands and fractures were investigated using time-resolved x-ray tomography and Digital Volume Correlation (DVC). Volumetric and shear strain fields were calculated using the SPAM software (Stamati et al., 2020). The orientation of the recently formed failure planes is influenced by the orientation of the pre-existing bands, as well as their width and the presence (or absence) of porosity along their length. Additionally, pre-existing secondary deformation features found in the tested material trigger additional mechanical damage that either promotes the development or deflects the new failure planes.

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Abstract: Accurately estimating developmental age and life history traits in fossils is crucial for identifying and classifying extinct species and understanding how biological attributes evolved. The evolution of life history traits such as growth pattern is far from clear in birds, and development has been studied in only a handful of modern species. The exceptionally rapid growth of modern birds means ageing methods based on annual incremental growth lines, used in other vertebrates, are inapplicable to birds and robust alternative methods remain to be established. Analysis of avian intracortical bone microstructure, which varies both with age and tissue deposition rate, is a promising approach already used in palaeobiology. However, current thin section-based histological methods are destructive. Moreover, to date, most microstructural studies in avian bone are qualitative, 2D, and involve a limited range of extant species. The objective of this study was to investigate cortical bone microstructure and developmental age and life history traits in living birds, to identify phenotypes which can then be applied to examination of the fossil record, using minimally-destructive high-resolution 3D imaging. First, the necessity of 3D measurement was tested: a combination of idealised, simulated datasets and real synchrotron-based computed tomography (SR CT) datasets were used to compare published methods for measuring key microstructural traits based on 2D sections and 3D volumes. Next, SR CT imaging and quantitative measurements were used to characterise age-related changes in bone microstructure in a range of extant bird species: growth series ducks and pheasants, and a smaller sample size in starlings, rock doves, partridges, and ostrich. The methods tested in modern material were applied to fossils as a proof-of concept. It was found that 3D quantification methods are required for measuring vascular canal orientation and osteocyte lacunar shape and volume, though 2D sections could be used to measure traits such as bone volume fraction (BV/TV) and osteocyte lacunar volume. In all species studied, juvenile, subadult, and adult species could be distinguished by their values of BV/TV, and further information could be added using measured values of vascular canal diameter as well as qualitative assessment. Using a synchrotron-based CT system, high-resolution 3D datasets comparable to modern bone samples were obtained from fossils, and preliminary estimates of developmental age can be made. Further work may reveal more changes within juvenile age stages, and better characterise the variation within extant birds, allowing more accurate interpretation of the fossil record. Therefore developmental studies in a greater number of extant bird species are required using larger sample sizes, to support and add to the results presented in this thesis.

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Abstract: Increasing electrode thickness is gaining more attention as a potential route to increase energy density for Li ion batteries although the realizable capacity and rate capability are usually limited by Li+ ion diffusion during (dis)charge, especially at increased (dis)charge rates. It remains challenging to visualize and quantify the low atomic number Li+ chemical stoichiometry distribution inside the electrode within commercially standard battery geometry, e.g., coin cells with stainless steel casings. Here, we map the distribution of Li+ chemical stoichiometry in the electrode microstructure inside a working coin cell battery to show the amount of electrode materials contributing to energy storage performance using innovative in situ correlative full-field X-ray Compton scattering imaging (XCS-I) and X-ray computed tomography (XCT). We design and fabricate an ultra-thick (∼1 mm) cathode of LiNi0.8Mn0.1Co0.1O2 with a microstructure containing vertically oriented pore arrays using a directional ice templating method. This novel technique paves a new way to map low atomic number elements in 3D structures and study how the microstructure improves Li+ ion diffusivity and energy storage performance.