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Abstract: Corrosion research related to CO2-containing environments has focused over the past few decades on siderite formation (FeCO3) as a main corrosion product on carbon steel, yet the influence of Ca and other ions on its chemical and structural characteristics is not fully understood. Metal-localized corrosion is the biggest industrial challenge because of the unknown and unpredictable character of this phenomenon that frequently leads to failure. We report here the role of Ca and formation of iron-calcium carbonate (FexCayCO3) through a spiral growth model as in the calcite system and quantify the replacement of Fe2+ by Ca2+ ions in the structure of FeCO3 to form FexCayCO3. The incorporation of Ca2+ inhibits the completion of spiral segments on the growth of the rhombohedral crystals of FeCO3, promoting an enlargement of its structure along the c-axis. This leads to distortions in the chemical structure and morphology affecting the chemical and mechanical properties. Under flow conditions over time in an undersaturated environment, Ca is leached out from the expanded structure of FexCayCO3 increasing the solubility of the crystals, weakening the mechanical properties of the resulting corrosion films and stimulating localized corrosion.

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Abstract: Background: Skogsbergia lerneri (Kornicker, 1958) is a species of ostracod which, like all crustaceans, has a protective exoskeleton (or carapace). As well as being used for a protective function, the S. lerneri carapace is also transparent. Understanding how the carapace is transparent while retaining its protective function was the primary aim of this thesis. Results: Ultrastructural analysis showed that the carapace consisted of an epicuticle, exocuticle and an endocuticle split into a calcified, crystalline endocuticle and a laminated endocuticle. Numerous structural adaptations were seen to minimise refractive index changes at the layer intersections. These layers developed along with growth of the ostracod, maintaining similar proportions throughout. Microstructural analysis identified a chitin based second harmonic generated signal from the carapace. Pixel analysis of this signal showed a consistent level of chitin expression (~60-80% of the total carapace) throughout all the developmental stages except instar 4, which showed a lower level of expression. Elemental analysis showed that the calcified, crystalline layer comprised mainly calcium, oxygen and magnesium, leading to the assumption that the structures were calcium carbonate. X-ray absorption near edge structure analysis revealed that the calcium carbonate consisted of entirely amorphous calcium carbonate in the early to middle stages of development and a mix of amorphous and aragonite in the later stages. Unlike most crustaceans, calcite was not seen in any carapaces. Optical testing showed a consistent refractive index across all stages (1.401-1.406) leading to a mean 99.94% transmission of light at the carapace surface in seawater. Spectrophotometric results showed that light transmission increased at longer wavelengths in the younger samples but maintained a consistent level by the adult stage. Conclusions: Through the various structural adaptations of the carapace, in combination with the rare calcium carbonate polymorph distribution and its overall thinness, the S. lerneri is able to maintain its transparency without sacrificing many of its physical properties.

Open Access

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Abstract: In this work, the effects of the protozoan Neospora caninum on the bioenergetics, chemical composition, and elemental content of human brain microvascular endothelial cells (hBMECs) were investigated. We showed that N. caninum can impair cell mitochondrial (Mt) function and causes an arrest in host cell cycling at S and G2 phases. These adverse effects were also associated with altered expression of genes involved in Mt energy metabolism, suggesting Mt dysfunction caused by N. caninum infection. Fourier Transform Infrared (FTIR) spectroscopy analysis of hBMECs revealed alterations in the FTIR bands as a function of infection, where infected cells showed alterations in the absorption bands of lipid (2924 cm−1), amide I protein (1649 cm−1), amide II protein (1537 cm−1), nucleic acids and carbohydrates (1092 cm−1, 1047 cm−1, and 939 cm−1). By using quantitative synchrotron radiation X-ray fluorescence (μSR-XRF) imaging and quantification of the trace elements Zn, Cu and Fe, we detected an increase in the levels of Zn and Cu from 3 to 24 h post infection (hpi) in infected cells compared to control cells, but there were no changes in the level of Fe. We also used Affymetrix array technology to investigate the global alteration in gene expression of hBMECs and rat brain microvascular endothelial cells (rBMVECs) in response to N. caninum infection at 24 hpi. The result of transcriptome profiling identified differentially expressed genes involved mainly in immune response, lipid metabolism and apoptosis. These data further our understanding of the molecular events that shape the interaction between N. caninum and blood-brain-barrier endothelial cells.

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Abstract: Mankind is facing a phosphorus (P) crisis. P recycling from anthropogenic waste is critical to close the P loop. Pyrolysis could be the ideal treatment for materials, such as sewage sludge, producing a safe, nutrient-rich biochar product while sequestering the inherent carbon (C). However, pyrolysed sewage sludge typically contains low levels of potassium (K) and plant available P making the material rather unsuitable for use as fertiliser. Here, a novel treatment was investigated to produce an optimised P and K biochar fertiliser. We doped sewage sludge with a low-cost mineral (2 and 5% potassium acetate) and pyrolysed it at 700°C. The percentage water-extractable of the total P content in biochar increased by 237-times with 5% K addition compared to the undoped biochar. After six water-extractions, all the K and 16% of P was obtained. Further optimisation is feasible through adjustments of the biochar pH or doping the feedstock with other forms of K. Using XANES and synchrotron XRF mapping, we identified highly soluble potassium hydrogen phosphate up to 200-300 µm below the biochar surface. This simple and cost-effective modification enables the use of sewage sludge as safe biochar fertiliser with tailored P availability that also supplies K, improves soil properties and sequesters C.

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Abstract: In this work, we present the results from multi-length-scale studies of a Mn-Na-W/SiO2 and a La-promoted Mn-Na-W/SiO2 catalyst during the oxidative coupling of methane reaction. The catalysts were investigated from the reactor level (mm scale) down to the single catalyst particle level (μm scale) with different synchrotron X-ray chemical computed tomography techniques (multi-modal chemical CT experiments). These operando spatially-resolved studies performed with XRD-CT (catalytic reactor) and multi-modal μ-XRF/XRD/absorption CT (single catalyst particle) revealed the multiple roles of the La promoter and how it provides the enhancement in catalyst performance. It is also shown that non-crystalline Mn species are part of the active catalyst component rather than crystalline Mn2O3/Mn7SiO12 or MnWO4.