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Shearing P.R.,Imperial College London | Gelb J.,Xradia Inc. | Brandon N.P.,Imperial College London
Journal of the European Ceramic Society

High-resolution tomography techniques have facilitated an improved understanding of solid oxide fuel cell (SOFC) electrode microstructures.The use of X-ray nano computerised tomography (nano-CT) imposes some geometrical constraints on the sample under investigation; in this paper, we present the development of an advanced preparation technique to optimise sample geometries for X-ray nano-CT, utilizing a focused ion beam (FIB) system to shape the sample according to the X-ray field of view at the required magnification.The technique has been successfully applied to a Ni-YSZ electrode material: X-ray nano-CT has been conducted at varying length scales and is shown to provide good agreement; comparison of results from X-ray and more conventional FIB tomography is also demonstrated to be favourable.Tomographic reconstructions of SOFC electrodes with volumes spanning two orders of magnitude are presented. © 2010 Elsevier Ltd. Source

Gelb J.,Xradia Inc.
Advanced Materials and Processes

In contrast to conventional x-ray CT setups, the long working distance and switchable magnification afforded by x-ray microscopy enables investigation of materials in their true natural state without sectioning for high-resolution 4-D studies. XRM accommodates in-situ experimental apparatuses including commercial batteries and compression and tensile loading stages. The technique can be extended to tens of nanometers length scale using x-ray optics for nondestructive 4-D investigation of today's advanced materials. Source

Shearing P.R.,Imperial College London | Gelb J.,Xradia Inc. | Yi J.,Argonne National Laboratory | Lee W.-K.,Argonne National Laboratory | And 2 more authors.
Electrochemistry Communications

Here, we demonstrate the use of X-ray absorption edge spectroscopy in conjunction with high resolution X-ray nano-computed tomography to provide a comprehensive microstructural map of a Ni-YSZ electrode from a Solid Oxide Fuel Cell. The experimentally derived microstructure has been used to develop a geometrical test for microstructural homogeneity. © 2010 Elsevier B.V. All rights reserved. Source

Ho S.P.,University of California at San Francisco | Kurylo M.P.,University of California at San Francisco | Fong T.K.,Xradia Inc. | Lee S.S.J.,University of California at San Francisco | And 3 more authors.

The relative motion between the tooth and alveolar bone is facilitated by the soft-hard tissue interfaces which include periodontal ligament-bone (PDL-bone) and periodontal ligament-cementum (PDL-cementum). The soft-hard tissue interfaces are responsible for attachment and are critical to the overall biomechanical efficiency of the bone-tooth complex. In this study, the PDL-bone and PDL-cementum attachment sites in human molars were investigated to identify the structural orientation and integration of the PDL with bone and cementum. These attachment sites were characterized from a combined materials and mechanics perspective and were related to macro-scale function. High resolution complimentary imaging techniques including atomic force microscopy, scanning electron microscopy and micro-scale X-ray computed tomography (Micro XCT™) illustrated two distinct orientations of PDL; circumferential-PDL (cir-PDL) and radial-PDL (rad-PDL). Within the PDL-space, the primary orientation of the ligament was radial (rad-PDL) as is well known. Interestingly, circumferential orientation of PDL continuous with rad-PDL was observed adjacent to alveolar bone and cementum. The integration of the cir-PDL was identified by 1-2 μm diameter PDL-inserts or Sharpey's fibers in alveolar bone and cementum. Chemically and biochemically the cir-PDL adjacent to bone and cementum was identified by relatively higher carbon and lower calcium including the localization of small leucine rich proteins responsible for maintaining soft-hard tissue cohesion, stiffness and hygroscopic nature of PDL-bone and PDL-cementum attachment sites. The combined structural and chemical properties provided graded stiffness characteristics of PDL-bone (Er range for PDL: 10-50MPa; bone: 0.2-9.6 GPa) and PDL-cementum (Er range for cementum: 1.1-8.3 GPa), which was related to the macro-scale function of the bone-tooth complex. © 2010. Source

A multi energy, such as dual-energy (DE), x-ray imaging system data acquisition and image reconstruction system and method enables optimizing the image contrast of a sample. Using the DE x-ray imaging system and its associated user interface applications, an operator performs a low energy (LE) and high energy (HE) x-ray scan of the same volume of interest of the sample. The system creates a low-energy reconstructed tomographic volume data set from the set of low-energy projections and a high-energy tomographic volume data set from the set of high-energy projections. This enables the operator to control the image contrast of selected slices, and apply the information associated with optimizing the contrast of the selected slice to all slices in the low-energy and high-energy tomographic data sets. This creates a combined volume data set from the LE and HE volume data sets with optimized image contrast throughout.

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