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• Multi-modal synchrotron µ-computed tomography (Sr-µCT) of neutron irradiated U-Mo. • Absorption and phase contrast Sr-µCT measured 3D porosity, swelling and composition. • A multilayered pore structure forms parallel to U-Mo/Zr interface at high-burnup. • Large interconnected and oriented pores form ∼5 µm from the U-Mo/Zr interface, which can lead to delamination. • Average local thickness of the Zr diffusion barrier was reduced by 53 %. The three-dimensional (3D) microstructure of neutron-irradiated uranium-10 wt.% molybdenum (U-10Mo) fuel with a burn-up of 9.8 × 1021 fissions/cm3 was characterized using a novel, multi-modal synchrotron micro-computed tomography approach combining propagation-based phase-contrast enhanced and absorption contrast techniques. The porosity development, porosity interconnectedness, swelling, composition, local thickness of the zirconium (Zr) diffusion barrier, and the influence of the fuel–cladding interaction on the local composition and pore morphology, were uniquely determined in 3D. Two cuboids were produced using a focused ion beam-scanning electron microscope at the Zr diffusion barrier–fuel interface and in the bulk fuel. The bulk fuel sample swelled by 53.3 [+9.7/−3.1]%, while the fuel near the Zr–fuel interface swelled by 63.3 [+14.7/−7.2]%. The average local thickness of the Zr diffusion barrier decreased by 53 %, compared to the expected pre-irradiated thickness. Four pore morphology regions were identified initiating parallel to the fuel–Zr interaction region: (1) an interaction layer of suppressed porosity, (2) a layer of elongated and interconnected porosity, (3) a transition zone of low porosity, and (4) a layer of unoriented porosity representative of the bulk fuel behavior. The increase in porosity near the diffusion barrier corresponded to a higher U concentration compared to that in the bulk fuel. The interconnected porosity in the fuel near the diffusion barrier was extensive and oriented parallel to the diffusion barrier, while the bulk fuel had more compact and isolated pore networks. The interaction layer, despite having suppressed porosity, was nearly 100 wt.% U. Porosity suppression at the diffusion barrier corresponds to the expected reduction in radiation-driven diffusion of Xe at the interface despite the anticipated increase in fission product nucleation originating from a higher U concentration. The novel 3D insights of the porosity, swelling, and compositional variations characterized herein can improve the fidelity of fuel performance codes for proliferation-resistant fuels for research and test reactors. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The senescence-accelerated mouse strain P6 (SAMP6) is a model of senile osteoporosis, which possesses many features of senile osteoporosis in humans. So far, little is known about the systemic bone microstructural changes that occur at the cervical, thoracic, and lumbar vertebrae. In this study, we therefore investigated segmental variations of vertebral trabecular bone mineral density (BMD) and three-dimensional microstructure in SAMP6 and the normal control mouse (SAMR1) at 12months of age using quantitative micro computed tomography (micro-CT) and image analysis software. The vertebral height and vertebral cross-sectional area (CSA) increased, while vertebral trabecular BMD and trabecular bone volume fraction (BV/TV) decreased from the cervical to lumbar spine both in SAMR1 and SAMP6. As compared with SAMR1, the thoracic vertebral CSA had a tendency to be low and the lumbar vertebral CSA was significantly declined in SAMP6. The vertebral trabecular BMD, BV/TV, trabecular thickness (Tb.Th), and trabecular number (Tb.N) significantly decreased in cervical, thoracic and lumbar spine of SAMP6. Trabecular bone pattern factor (TBPf) was higher at the lumbar spine and the structure model index (SMI) of the lower thoracic and lumbar spine was higher in SAMP6. These results indicate that vertebral trabecular bone microstructures are remarkably heterogeneous throughout the spine in both SAMR1 and SAMP6. The decrease of vertebral trabecular bone density in SAMP6 advanced faster caudally than cranially within the spine, similar phenomena were observed in humans. These findings highlight the relevance of SAMP6 for studies of vertebral fragility associated with senile osteoporosis. [Copyright &y& Elsevier]

The purpose of this study was to develop the methods needed to enable the application of Immunofluorescent Array Tomography (IAT), a novel three-dimensional (3D) microscopy technique, to murine blood vessels. The anterior and posterior regions of the infrarenal aorta of 8-10 week old C57BL6 mice were evaluated. Staining and image analysis methods were developed. Antibody selection, primary antibody concentration, co-staining with multiple primary antibodies, and the multi-cycle staining design were optimized to produce positive and specific staining of elastin (1:50 dilution), smooth muscle cell actin (SMCA, 20 μg mL), and collagen type I (10 μg mL). Non-specific interactions were limited by optimizing secondary antibody staining conditions (1:200 dilution, 30 min). SMCA and collagen type I were stained in the first cycle, elastin was stained in the second cycle, and nuclei were stained in both cycles. Algorithms were developed to quantify volume fractions of medial elastin, SMCA, and nuclei, as well as adventitial collagen type I. Elastin thickness, spacing between elastin lamellae, elastin fragmentation, media wall thickness, nuclei aspect ratio, and nuclei amount were also quantified. We have qualitatively and quantitatively characterized the 3D microstructure and cellular morphology of the anterior and posterior infrarenal murine aorta using IAT. [ABSTRACT FROM AUTHOR]

Abstract: The senescence-accelerated mouse strain P6 (SAMP6) is a model of senile osteoporosis, which possesses many features of senile osteoporosis in humans. So far, little is known about the systemic bone microstructural changes that occur at multiple skeletal sites. In this study, we therefore, investigated site (vertebra, femur and tibia) dependence of bone microstructure and bone mineral density (BMD) in SAMP6 and the normal control mouse (SAMR1) at 5 and 12months of age using quantitative micro computed tomography (micro-CT) and image analysis software. As compared with SAMR1, the most prominent change in SAMP6 was the reduction of vertebral trabecular bone volume fraction (BV/TV) and trabecular BMD. Moderate decrease of trabecular bone mass was observed in the proximal tibia and distal femur. Increased marrow area and periosteal perimeter were investigated, though the cortical area and cortical thickness had no marked changes in the mid-tibial and mid-femoral cortical bones. These results indicate that bone microstructural properties in SAMP6 are remarkably heterogeneous throughout the skeleton, which is analogous to changes that occur in human bones. These findings further validate the relevance of SAMP6 as a model of senile osteoporosis. [Copyright &y& Elsevier]

A three-dimensional (3D) microstructure of Fe-intermetallic compounds (Fe-IMCs) was analyzed by means of x-ray tomography. 3D images were obtained to understand the internal structure of the Fe-IMCs in Al-Si-Mg-Fe alloys. A needle-shaped β phase appears in two-dimensional (2D) observations while platelet and irregular morphologies of the Fe-IMCs are identified in 3D investigations. The reconstructed microstructure was roughly crushed with 20% reduction rates and less broken parts of Fe-IMCs are observed, showing platelet and blunt morphologies. The combination of a large- and small-volume of the Fe-IMCs remained after a 60% reduction rate. The needle- and lateral-shaped of the Fe compounds were finely fragmented into the micro- and/or nano-scale at a 80% reduction rate. The average size of the Fe-IMCs is refined from 20.3 to 2.9 μm at the 80% reduction rate. The largest size of the Fe-IMCs is shortened from 85.5 to 21.3 μm. It is considered that fracture is affected by the length of the Fe-IMCs. Rapid cracks initiated around the fragmented Fe-IMCs at the reduction rate of 40% because the number of the Fe-IMCs is increased due to fragmentation. On the other hand, the harmful influence of Fe-IMCs on elongation becomes positive when the length of the Fe-IMCs decreases to less than a critical size. [ABSTRACT FROM AUTHOR]