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Abstract: Alternative battery technologies are required to meet growing energy demands and address the limitations of present technologies. As such, it is necessary to look beyond lithium-ion batteries. Zinc batteries enable high power density while being sourced from ubiquitous and cost-effective materials. This paper presents, for the first time known to the authors, multi-length scale tomography studies of failure mechanisms in zinc batteries with and without commercial microporous separators. In both cases, dendrites were grown, dissolved, and regrown, critically resulting in different morphology of dendritic layer formed on both the electrode and the separator. The growth of dendrites and their volume-specific areas were quantified using tomography and radiography data in unprecedented resolution. High-resolution ex situ analysis was employed to characterize single dendrites and dendritic deposits inside the separator. The findings provide unique insights into mechanisms of metal-battery failure effected by growing dendrites.

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Abstract: Recent advancements in fast synchrotron x-ray tomography has made it possible to acquire time-resolved 3D image volumes (4D Imaging) of different materials including paper that can be utilized for direct observation of their microstructure under deformation. Considering the importance of inter-fibre bonding in prediction of paper behaviour, especially when paper is formed from a pulp mixture, this thesis devises a method to evaluate the level of inter-fibre bonding using 4D imaging experiments. To do so, four samples with different levels of bonding, and six samples with different fractions of NBSK and Eucalyptus fibres were scanned by synchrotron x-ray tomography while being deformed in a tensile tester in an interrupted fashion. Qualitative observations of the sample with the weakest level of bonding revealed some significant thickness expansions in and around the regions of failure. Measurements of fibre-fibre contacts and curl index showed that inter-fibre bond breakage, in addition to fibre straightening, are the underlying mechanisms for such thickness expansions. This lead to a conclusion that out-of-plane deformations of paper samples during tensile testing can be used as a criterion to measure the level of bonding inside their networks. Qualitative observations of the samples with different levels of bonding showed that there is a strong correlation between such thickness expansions and the levels of bonding further confirming that out-of-plane deformations can be used as a measure to evaluate network efficiency. To do so, norms of the out-of-plane strain fields obtained from DVC analysis were used to quantify such thickness expansions that also showed strong correlation with the levels of bonding. Application of such analysis on mixture samples revealed some unexpected results where 100% NBSK samples showed higher thickness expansions when compared to 100% Eucalyptus samples when 100% NBSK sample is expected to have higher levels of bonding. This trend was explained by an increase of the free fibre lengths due to addition of longer fibres to the pulp mixture. This underlined the need for consideration of the contribution of free fibre lengths to such thickness expansions to evaluate the level of bonding inside samples made from mixture of fibres that have different lengths.

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Abstract: Hyperspectral X-ray detectors, which provide the full energy spectrum detected by each individual pixel, have become available for use in lab-based facilities. The addition of spectral information currently comes at the cost of low overall acceptable flux rates, and can introduce countrate nonlinearity at higher energies. Neither of these drawbacks are desirable for transmission imaging and tomography. In this paper a new data processing software chain is presented for the SLcam, a pnCCD-based hyperspectral camera prototype, allowing for more control over the conversion from raw frames to hyperspectral images. Complementary to the processing software, a set of live data visualisations was developed to aid in monitoring ongoing experiments and to allow for preliminary data processing on-the-fly. The combination of these software elements forms the first step towards general applicability of hyperspectral imaging at laboratory tomography setups.

Open Access

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Abstract: Aortic wall remodelling is a key feature of both ageing and genetic connective tissue diseases, which are associated with vasculopathies such as Marfan syndrome (MFS). Although the aorta is a 3D structure, little attention has been paid to volumetric assessment, primarily due to the limitations of conventional imaging techniques. Phase-contrast microCT is an emerging imaging technique, which is able to resolve the 3D micro-scale structure of large samples without the need for staining or sectioning. Methods: Here, we have used synchrotron-based phase-contrast microCT to image aortae of wild type (WT) and MFS Fbn1C1039G/+ mice aged 3, 6 and 9 months old (n=5). We have also developed a new computational approach to automatically measure key histological parameters. Results: This analysis revealed that WT mice undergo age-dependent aortic remodelling characterised by increases in ascending aorta diameter, tunica media thickness and cross-sectional area. The MFS aortic wall was subject to comparable remodelling, but the magnitudes of the changes were significantly exacerbated, particularly in 9 month-old MFS mice with ascending aorta wall dilations. Moreover, this morphological remodelling in MFS aorta included internal elastic lamina surface breaks that extended throughout the MFS ascending aorta and were already evident in animals who had not yet developed aneurysms. Conclusions: Our 3D microCT study of the sub-micron wall structure of whole, intact aorta reveals that histological remodelling of the tunica media in MFS could be viewed as an accelerated ageing process, and that phase-contrast microCT combined with computational image analysis allows the visualisation and quantification of 3D morphological remodelling in large volumes of unstained vascular tissues.

Open Access

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Abstract: Ice cream is a complex multi-phase colloidal soft-solid and its three-dimensional microstructure plays a critical role in determining the oral sensory experience or mouthfeel. Using in-line phase contrast synchrotron X-ray tomography, we capture the rapid evolution of the ice cream microstructure during heat shock conditions in situ and operando, on a time scale of minutes. The further evolution of the ice cream microstructure during storage and abuse was captured using ex situ tomography on a time scale of days. The morphology of the ice crystals and unfrozen matrix during these thermal cycles was quantified as an indicator for the texture and oral sensory perception. Our results reveal that the coarsening is due to both Ostwald ripening and physical agglomeration, enhancing our understanding of the microstructural evolution of ice cream during both manufacturing and storage. The microstructural evolution of this complex material was quantified, providing new insights into the behavior of soft-solids and semi-solids, including many foodstuffs, and invaluable data to both inform and validate models of their processing.