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Abstract: Al3Ti, Al13Cr2 and Al13Fe4 are important intermetallics in a number of Al alloy systems including complex ultra-high-strength systems with excellent elevated-temperature performance. A full knowledge of their properties and crystallographic structures is a key factor for the understanding of these complex alloys. In the present study samples of the three pure intermetallics were prepared and regions of interest identified in a billet of Al93Fe3Cr2Ti2 alloys and 20 × 10 × 2 µm samples extracted utilizing a Focussed Ion Beam Transmission Electron Microscopy (FIB TEM) sample preparation technique. Using the microfocus spectroscopy beamline I18 at Diamond Light Source we were able to examine 5 µm sections of the samples using X-ray Diffraction (?-XRD) and Extended X-ray Absorption Fine Structure (?-EXAFS) in an attempt to describe the local structure of the second-phase particles and characterized the microstructure of the FIBed samples to selectively illuminate the different phases.

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Abstract: Thermal spraying is emerging as the leading route for the deposition of protective coatings onto engineering components to improve operation under extreme conditions of temperature, wear or corrosion. Detailed microstructural assessment is a key element in improving coating performance, and this study demonstrates the application of microfocus X-ray techniques to the determination of elemental and structural variations in the coatings.

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Abstract: Shales play an important role in many earth system processes including coastal erosion, and they form the foundations of many engineering structures. The geobiology of the interior of pyrite-containing receding shale cliffs on the coast of northeast England was examined. The surface of the weathered shales was characterised by a thin layer of disordered authigenic iron oxyhydroxides and localised acicular, platy and aggregated gypsum, which was characterised by Raman spectroscopy, XAS and SEM. These chemical changes are likely to play an important role in causing rock weakening along fractures at the micron scale, which ultimately lead to coastal retreat at the larger scale. The surface of the shale hosts a novel, low-diversity microbial community. The bacterial community was dominated by Proteobacteria, with phylotypes closely associating with Methylocella and other members of the γ-subdivision. The second largest phylogenetic group corresponded to Nitrospira. The archaeal 16S rRNA phylotypes were dominated by a single group of sequences that matched phylotypes reported from South African gold mines and possessed ammonia monooxygenase (amoA) genes. Both the phylogenetic and the mineral data show that acidic microenvironments play an important role in shale weathering, but the shale has a higher microbial diversity than previously described pyritic acid mine drainage sites. The presence of a potentially biogeochemically active microbial population on the rock surface suggests that microorganisms may contribute to early events of shale degradation and coastal erosion.

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Abstract: Several amyloidogenic proteins including insulin, ?-lactoglobulin, and albumin form spherulites in vitro under non-physiological conditions. These micrometer-sized, roughly spherical structures are composed of ordered arrays of amyloid fibrils in radial arrangements which, characteristically, show a typical Maltese cross pattern of light extinction under the polarizing microscope. The physiological significance of amyloid spherulites is unknown though in Alzheimer's disease, senile plaques composed primarily of ? sheets of amyloid-? (A?){42} have, very occasionally, been shown to give a Maltese cross pattern of light extinction under crossed polarizers. Herein we describe the first observation of the formation in vitro of spherulites of A?{42}. They were formed under near-physiological conditions in which the ? sheet conformation of pre-formed aggregates of A?{42} had been abolished following the addition of an excess of copper. Incubation of these preparations at 37°C for up to 9 months resulted in the formation of globular structures, 5–20 ?m in diameter, which exhibited a Maltese cross pattern of light extinction typical of spherulites. Near-identical spherulitic structures were also observed in abundance in 30 ?m thick sections of Alzheimer's disease brain tissue. Synchrotron x-ray fluorescence showed that the location of these spherulites in AD tissue coincided with locally elevated concentrations of tissue copper. The formation in vitro of spherulites of A?{42} which morphologically appeared analogous to spherulitic structures observed in vivo strongly supports the hypothesis that spherulites and senile plaques in AD tissue are one and the same structures and that their ultimate formation may involve copper.