The three-dimensional (3-D) architecture of rigid multiphase networks present in AlSi10Cu5Ni1 and AlSi10Cu5Ni2 piston alloys in as-cast condition and after 4h spheroidization treatment is ...characterized by synchrotron tomography in terms of the volume fraction of rigid phases, interconnectivity, contiguity and morphology. The architecture of both alloys consists of α-Al matrix and a rigid long-range 3-D network of Al7Cu4Ni, Al4Cu2Mg8Si7, Al2Cu, Al15Si2(FeMn)3 and AlSiFeNiCu aluminides and Si. The investigated architectural parameters of both alloys studied are correlated with room-temperature and high-temperature (300°C) strengths as a function of solution treatment time. The AlSi10Cu5Ni1 and AlSi10Cu5Ni2 alloys behave like metal matrix composites with 16 and 20vol.% reinforcement, respectively. Both alloys have similar strengths in the as-cast condition, but the AlSi10Cu5Ni2 is able to retain ∼15% higher high temperature strength than the AlSi10Cu5Ni1 alloy after more than 4h of spheroidization treatment. This is due to the preservation of the 3-D interconnectivity and the morphology of the rigid network, which is governed by the higher degree of contiguity between aluminides and Si.
Imaging intact human organs from the organ to the cellular scale in three dimensions is a goal of biomedical imaging. To meet this challenge, we developed hierarchical phase-contrast tomography ...(HiP-CT), an X-ray phase propagation technique using the European Synchrotron Radiation Facility (ESRF)'s Extremely Brilliant Source (EBS). The spatial coherence of the ESRF-EBS combined with our beamline equipment, sample preparation and scanning developments enabled us to perform non-destructive, three-dimensional (3D) scans with hierarchically increasing resolution at any location in whole human organs. We applied HiP-CT to image five intact human organ types: brain, lung, heart, kidney and spleen. HiP-CT provided a structural overview of each whole organ followed by multiple higher-resolution volumes of interest, capturing organotypic functional units and certain individual specialized cells within intact human organs. We demonstrate the potential applications of HiP-CT through quantification and morphometry of glomeruli in an intact human kidney and identification of regional changes in the tissue architecture in a lung from a deceased donor with coronavirus disease 2019 (COVID-19).
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Pores are often present in large aluminum ingots after casting. To ensure the mechanical reliability of the final thick plates, these pores must be closed during the forming process, ...hot rolling in the present case. This study aims at understanding the effects of rolling parameters on the volume evolution of pores. To do so, X-ray microtomography is used to track real casting pores during deformation. Nevertheless, thick plates are too large to enable a fine characterization of the evolution of pores during the process. The size and shape of the samples as well as the mechanical boundary conditions must be optimized to meet imaging constraints. This paper focuses on the reproduction of complex loading paths. Multi-scale FE simulations are used to reproduce the loading conditions of thick plate rolling with uniaxial tests on samples of a few millimeters. Uniaxial tests are then characterized with tomography on a synchrotron X-ray beamline. In each sample, tens of pores are individually tracked, giving access to their volume evolution. The local loading path experienced by each pore is determined with FE simulation. It is shown that the volume evolution of a real pore correlates with the hydrostatic integration which is the integral of stress triaxiality along cumulated strain. This confirms that the closure of complex casting pores is enhanced by a high relative reduction and high values of L/H ratio during rolling similarly to what was observed numerically on simpler shapes.
The microstructural evolution of an Al–10
wt.% Cu alloy was investigated during solidification at constant cooling rate by in situ synchrotron X-ray microtomography with a resolution of 2.8
μm. ...Solidification of this alloy leads to a coarse dendritic microstructure which was fully characterized in terms of variation with temperature of the solid fraction, the specific surface area of the solid–liquid interface and the local curvatures of the solid phase. By analysing the evolution with solid fraction of individual dendrites, at least two coarsening mechanisms were clearly identified in addition to solidification growth. The first mechanism involves remelting of small secondary dendrite arms to the benefit of bigger adjacent arms. The second is the coalescence of adjacent secondary arms, with progressive filling of the inter-arm spacing and coalescence at the tips. Although this mechanism preferentially occurs at high solid fractions, these results show that the evolution of the dendritic microstructure during solidification is complex and involves the occurrence of various mechanisms operating concurrently. In situ X-ray tomography thus allows revisiting the various models which have been proposed to account for dendrite coarsening during solidification.
This thematic review examines the literature regarding the relationship between domestic violence (DV) and pet abuse (PA) particularly in the veterinary clinical and educational contexts. It examines ...the significance of this relationship for the veterinary profession including the veterinarian's role and associated legal and ethical obligations, and relevant current veterinary education standards, to identify future clinical and educational directions. Articles were sourced from online databases by searching the keywords without date restrictions. Overall, 70 articles were retrieved and reviewed.
Pet abuse has been identified as a potential risk factor for DV, and DV perpetrators may harm or kill a pet to exert physical, psychological or emotional control over an intimate partner. Given that victims of DV often seek veterinary aid for their pets, veterinarians may act as frontline professionals in the recognition of the link between PA and DV. Veterinarians must assess individual cases for diagnostic indicators of non-accidental injury and consider demographic factors to identify suspected PA and DV. Despite existing legal and ethical obligations of the veterinarian relating to suspected PA and victims of DV, veterinarians have uncertainty and unpreparedness in addressing PA and DV in a clinical context. Many factors may contribute to the lack of veterinary intervention in suspected cases of PA and DV including concern for animal welfare, confusion about the reporting process and uncertainty in differentiating accidental versus non-accidental injuries in pets. Specific published guidelines regarding the recognition and reporting of PA and DV in the veterinary clinical context are required. Limited published evidence exists examining the implementation and success of veterinary training regarding the relationship between DV and PA. Ultimately, veterinary student education is needed to prepare veterinarians for their response to PA and DV in practice. Further research is required to examine the effects of the delivery of content regarding the link between PA and DV in the veterinary curriculum on veterinary student knowledge and attitudes.
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Interrupted in situ tests at high temperature characterized with X-ray microtomography were employed to study porosity evolution under loading conditions representative of aluminum ...hot rolling. Coupling digital volume correlation and simulations, it is possible to access, for each pore, its morphological evolution, and the mechanical fields it experienced. The closure kinetics of hundreds of pores were studied, which is described as the pore volume as a function of the hydrostatic integration. Closure kinetics are a function of the shape of the pore. Focus is put on pores with a complex shape which are more detrimental to mechanical properties. Their closure kinetics are exponential due to the pore fragmentation during closure. The closure of complex pores is fostered by an initial orientation perpendicular to the loading direction and a low initial fragmentation. Based on the closure kinetics of 243 complex pores, a new pore closure model is proposed.
This paper aims at illustrating the potential of X-ray tomography for studying the mechanical behaviour of materials through
in situ
experiments. Typical experimental tomography set ups which use ...laboratory and synchrotron X ray sources are described; advantages and limitations of both types of sources are presented. Dedicated experimental devices which allow deformation and/or temperature changes to be applied to various types of materials are described. Examples of results of
in situ
mechanical experiments are presented and discussed; they include monotonic tensile testing of steel fiber entanglements, high temperature compression and room temperature fatigue of Al alloys. Examples of quantitative assessment of localisation of deformation in the interior of optically opaque samples under mechanical loading are also described.
The effect of impurities, Sr additions and cooling rate on the microstructural evolution of high-purity Al-10Si-0.3Fe and corresponding impure commercial alloys is examined by optical microscopy and ...in situ by X-ray synchrotron 3D tomography. At fast cooling rate (∼470 K min−1) the presence of impurities decreases the growth rate of primary Al dendrites and enables formation of the β phase. Besides a modification of the eutectic Si, the addition of Sr prevents the formation of the β phase and increases the growth rate of Al dendrites. A low cooling rate (∼1 K min−1) leads to the formation of α, γ, δ and β intermetallic phases. In all four alloys, the dominant phase is the δ phase, regardless of commercial impurities or the Sr level. Intermetallic phases formed during slow cooling rates are much coarser than those formed during fast cooling and they have different morphologies. Our results suggest that the velocity of growth and the final morphology and size of the intermetallic phases are mainly determined by diffusional processes which in turn are controlled by the cooling rate.
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•Ex-situ and In-situ X-ray synchrotron tomography was used for study the microstructure.•Influence of impurities, Sr addition and cooling rate on microstructure was investigated.•The presence of impurities enables formation of the most detrimental β intermetallic phase.•The addition of Sr prevents formation of the β intermetallic phase.•The cooling rate controlled the final sizes of the intermetallic phases.
X-ray tomography is a relevant technique for the dynamic follow-up of gas bubbles in an opaque viscoelastic matrix, especially using image analysis. It has been applied here to pieces of fermenting ...wheat flour dough of various compositions, at two different voxel sizes (15 and 5 μm). The resulting evolution of the main cellular features shows that the creation of cellular structures follows two regimes that are defined by a characteristic time of connectivity, tc 30 and 80 min: first (t ≤ tc), bubbles grow freely and then (t ≥ tc) they become connected since the percolation of the gas phase is limited by liquid films. During the first regime, bubbles can be tracked and the local strain rate can be measured. Its values (10(-4)-5 × 10(-4) s(-1)) are in agreement with those computed from dough viscosity and internal gas pressure, both of which depend on the composition. For higher porosity, P = 0.64 in our case, and thus occurring in the second regime, different cellular structures are obtained and XRT images show deformed gas cells that display complex shapes. The comparison of these images with confocal laser scanning microscopy images suggests the presence of liquid films that separate these cells. The dough can therefore be seen as a three-phase medium: viscoelastic matrix/gas cell/liquid phase. The contributions of the different levels of matter organization can be integrated by defining a capillary number (C = 0.1-1) that makes it possible to predict the macroscopic dough behavior.
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