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Abstract: Soil structure is one of the most important environmental factors affecting root architectural development and consequently plant yield. Understanding how plant roots respond to soils with variable soil structure is important as it enables soil management practices that promote optimal root growth. Many contemporary, non-invasive experiments investigating how plant root architecture responds to soil structural variations have often focused on compaction, often neglecting the role of soil aggregate size in determining root configuration. To better understand this, in this study, we used non-invasive neutron and X-Ray imaging to investigate how variable aggregate size affects the early root architectural establishment in wheat plants. Sandy loam soil derived macro-aggregates of two distinct sizes (0.25−0.5 and 2−4 mm) were used to infer the suitability of each aggregate size for use in wheat seedbeds. We also grew wheat seedlings in partitioned containers with the two different aggregate size classes filled side by side to establish whether there would be preferential growth of roots in either aggregate size class. Our results showed significantly increased root growth in the smaller 0.25−0.5 mm aggregates as compared to the larger 2−4 mm aggregates. This was mainly as a result of enhanced lateral root growth when the wheat plants were grown in the finer aggregates. On the other hand, coarser aggregates induced significantly increased seminal root axes which partially offset the differences in total root length between the two aggregate sizes. Plants growing in partitioned containers similarly indicated preferential root growth in smaller aggregate with an even more pronounced difference in root growth in the smaller aggregates. As inferred from our results, seedbeds dominated by smaller macro-aggregates (finer soil tilth) may be optimal to enhance wheat seedling root growth in sandy loam soils.

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Abstract: In this work, three new pharmaceutical salts of fenbendazole (FNB), a benzimidazole-based anthelmintic drug, with sulfonic acids have been obtained and thoroughly investigated by different analytical techniques, including thermal methods, infrared/Raman spectroscopy, and theoretical methods (periodic DFT computations and Bader analyses of the crystalline electronic density). Single-crystal and high-resolution synchrotron powder X-ray diffraction data for the first time made it possible to determine the crystal structures of mesylate and tosylate salts of the drug, which were further validated by dispersion-corrected density functional theory calculations. All the solid forms were stabilized by a robust R22(8) supramolecular motif formed by relatively strong N–H···O hydrogen bonds. In the monohydrate of FNB tosylate, a considerable gain in the stabilization energy was due to the intermolecular interactions generated by the water molecules. A careful examination of the solubility–pH profile of the FNB salts revealed that, despite being thermodynamically unstable within the physiologically relevant pH range, the new solid forms demonstrated superior dissolution performance in terms of both the apparent solubility and the release rate in comparison to the parent drug. Since FNB has also been reported to possess anticancer activity, improving the drug’s poor physicochemical properties through salt formation with the selected sulfonic acids is expected to promote further investigations toward repurposing of this potent compound.

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Abstract: Climate change, and the need of recycling, are two interconnected topics that are gaining more and more relevance nowadays. In order to decrease the CO2 emissions and reduce, or contain, the pollution that is having devastating effects on our climate, recycling seems to be a necessity that can not be postpone or diminished anymore. In the effort of reducing pollution, the aluminium world (industry and Academia) is playing an important role. Recycling aluminium, in fact, require only 10% of the energy necessary to extract it form the bauxite ore, leading to a massive energy and cost saving, as well to a reduction on the CO2 emissions equivalent to take off the road 900000 cars for 12 months. Up to now, the only closed loop recycling process is the one for usage beverage cans (UBC): used cans are collected, molten together, and used again to create new cans without the addition of any other material. When it comes to the automotive industry things are a bit more complicated. There are two main ways, adopted by industries, to recycle Al alloys depending on their composition. Wrought alloys are recycled remelting the scrap with primary Al, and cast alloys are obtained remelting wrought alloys and adjusting their composition for the different purposes. Although these two methods meet the requirement so far, they will lead to a nonrecyclable scrap surplus in the near future, consequently, new possibilities are being explored. In this work, a method to recycle aluminium alloys based on fractional solidification is proposed. The technology developed is based on an idea proposed by A.L Lux and M.C Flemings in which a semisolid alloy is isothermally squeezed towards a filter. Lux and Flemings tested their method on Sn-Pb alloys and on a small scale (500 g). The technology developed in this thesis, has been tested first on model aluminium alloys, and once the optimised procedure was established, on real aluminium scrap alloys, and on a bigger scale (up to 3 kg). The effect of several parameters (temperature, squeezing procedure, ultrasound, and grain refinement) on the purification efficiency was investigated and a 60% purification efficiency was achieved. Along with the technology development, a more fundamental study was carried out focusing on the investigation of the semisolid deformation, the liquid migration through the mush and the role of morphology on the permeability of the semisolid alloy. Finally, through the use of a numerical model, the feasibility of the Scheil-Gulliver approach to our case study, was investigated.

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Abstract: In this study we investigated the evolution of meso-scale internal stresses and those effects on local deformation behaviour during incremental plastic and creep deformation in type 316H stainless steel at 550°C, using in-situ X-ray synchrotron diffraction and crystal plasticity modelling. Owing to the fast data accusation rate of synchrotron diffraction technique, for the first time, the transient behaviour of different grain families was captured during initial fast stress relaxation period of the displacement-controlled creep dwells. Significantly it is found that the evolution of internal stresses during time independent plastic deformation is distinct from that during time dependent creep deformation. During plastic deformation, lattice strains in the {311} grain family exhibit linear behaviour whereas during creep deformation it exhibits non-linear behaviour, instead the {111} grain family exhibit linear behaviour. A novel unified constitutive law was devised within crystal plasticity framework based on the theoretical physics; the model successfully predicts the macroscopic deformation behaviour as well as the distinction between the evolution of meso-scale internal stresses during plastic and creep deformation, therefore, correctly accounting for the effect of internal stresses generated during plastic deformation on the subsequent creep deformation. The validated model has elucidated the grain-neighbouring effects on individual grain deformations.

Open Access

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Abstract: Accurate residual lattice strain measurements are highly dependent upon the precision of the diffraction peak location and the underlying microstructure suitability. The suitability of the microstructure is related to the requirement for valid powder diffraction sampling statistics and the associated number of appropriately orientated illuminated. In this work, these two sources of uncertainty are separated, and a method given for both the quantification of errors associated with insufficient grain sampling statistics and minimization of the total lattice strain measurement uncertainty. It is possible to reduce the total lattice strain measurement uncertainty by leveraging diffraction peak measurements made at multiple azimuthal angles. Lattice strain measurement data acquired during eight synchrotron X-ray diffraction experiments, monochromatic and energy dispersive, has been assessed as per this approach, with microstructural suitability being seen to dominate total measurement uncertainty when the number of illuminated grains was <106. More than half of the studied experimental data fell into this category, with a severe underestimation of total strain measurement uncertainty being possible when microstructural suitability is not considered. To achieve a strain measurement uncertainty under 10−4 , approximately 3×105 grains must be within the sampled gauge volume, with this value varying with the multiplicity of the family of lattice planes under study. Where additional azimuthally arrayed data are available an in-plane lattice strain tensor can be extracted. This improves overall strain measurement accuracy and an uncertainty under 10−4 can then be achieved with just 4×104 grains.