Organic Matter Pore Characterization in Lacustrine Shales with Variable Maturity Using Nanometer-Scale Resolution X-ray Computed Tomography

AbstractThe fraction of organic matter present affects the fragmentation behavior of sialoliths; thus, pretherapeutic information on the degree of mineralization is relevant for a correct selection of lithotripsy procedures. This work proposes a methodology for in vivo characterization of salivary calculi in the pretherapeutic context. Sialoliths were characterized in detail by X-ray computed microtomography (μCT) in combination with atomic emission spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Correlative analysis of the same specimens was performed by in vivo and ex vivo helical computed tomography (HCT) and ex vivo μCT. The mineral matter in the sialoliths consisted essentially of apatite (89 vol%) and whitlockite (11 vol%) with average density of 1.8 g/cm3. In hydrated conditions, the mineral mass prevailed with 53 ± 13 wt%, whereas the organic matter, with a density of 1.2 g/cm3, occupied 65 ± 10% of the sialoliths’ volume. A quantitative relation between sialoliths mineral density and X-ray attenuation is proposed for both HCT and μCT.

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Casting Pore Characterization by X-Ray Computed Tomography and Metallography

Archive of Mechanical Engineering ◽

10.2478/v10180-010-0014-y ◽

2010 ◽

Vol 57 (3) ◽

pp. 263-273 ◽

Cited By ~ 3

Author(s):

Stanislava Fintová ◽

Giancarlo Anzelotti ◽

Radomila Konečná ◽

Gianni Nicoletto

Keyword(s):

Computed Tomography ◽

Defect Size ◽

Fatigue Properties ◽

X Ray ◽

Aluminum Castings ◽

Pore Characterization ◽

Size Population ◽

X Ray Computed ◽

Definition Of ◽

Casting Porosity

Casting Pore Characterization by X-Ray Computed Tomography and MetallographyCasting porosity is the main factor influencing the fatigue properties of Al-Si alloys. Due to the increasing use of aluminum castings, porosity characterization is useful for estimating their fatigue strength. In principle, a combination of metallographic techniques and statistical pore analysis is a suitable approach for predicting the largest defect size that is critical for the casting. Here, the influence of modifiers and casting technology on the largest pore size population in AlSi7Mg alloy specimens is obtained and discussed adopting the Murakami's approach. However, porosity evaluation is a challenge in the case of microshrinkage pores, which are frequently found in industrial castings. Their complicated morphology prevents a reliable definition of an equivalent defect size based on metallographic techniques. This contribution reports the application of X-ray tomography to the 3D reconstruction of real pores in cast Al-Si alloys and provides insight into the complication of microshrinkage pore sizing by metallography.

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Resolving the Three-Dimensional Microstructure of Polymer Electrolyte Fuel Cell Electrodes using Nanometer-Scale X-ray Computed Tomography

Advanced Functional Materials ◽

10.1002/adfm.201101525 ◽

2011 ◽

Vol 22 (3) ◽

pp. 555-560 ◽

Cited By ~ 118

Author(s):

William K. Epting ◽

Jeff Gelb ◽

Shawn Litster

Keyword(s):

Computed Tomography ◽

Fuel Cell ◽

Polymer Electrolyte ◽

Three Dimensional ◽

Polymer Electrolyte Fuel Cell ◽

Nanometer Scale ◽

Fuel Cell Electrodes ◽

X Ray ◽

X Ray Computed

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Three-dimensional soil organic matter distribution, accessibility and microbial respiration in macroaggregates using osmium staining and synchrotron X-ray computed tomography

SOIL ◽

10.5194/soil-2-659-2016 ◽

2016 ◽

Vol 2 (4) ◽

pp. 659-671 ◽

Cited By ~ 13

Author(s):

Barry G. Rawlins ◽

Joanna Wragg ◽

Christina Reinhard ◽

Robert C. Atwood ◽

Alasdair Houston ◽

...

Keyword(s):

Computed Tomography ◽

Organic Matter ◽

Transition Probabilities ◽

Pore Space ◽

Pearson Correlation ◽

Soil Core ◽

Length Scales ◽

X Ray ◽

Mineral Phases ◽

X Ray Computed

Abstract. The spatial distribution and accessibility of organic matter (OM) to soil microbes in aggregates – determined by the fine-scale, 3-D distribution of OM, pores and mineral phases – may be an important control on the magnitude of soil heterotrophic respiration (SHR). Attempts to model SHR on fine scales requires data on the transition probabilities between adjacent pore space and soil OM, a measure of microbial accessibility to the latter. We used a combination of osmium staining and synchrotron X-ray computed tomography (CT) to determine the 3-D (voxel) distribution of these three phases (scale 6.6 µm) throughout nine aggregates taken from a single soil core (range of organic carbon (OC) concentrations: 4.2–7.7 %). Prior to the synchrotron analyses we had measured the magnitude of SHR for each aggregate over 24 h under controlled conditions (moisture content and temperature). We test the hypothesis that larger magnitudes of SHR will be observed in aggregates with (i) shorter length scales of OM variation (more aerobic microsites) and (ii) larger transition probabilities between OM and pore voxels. After scaling to their OC concentrations, there was a 6-fold variation in the magnitude of SHR for the nine aggregates. The distribution of pore diameters and tortuosity index values for pore branches was similar for each of the nine aggregates. The Pearson correlation between aggregate surface area (normalized by aggregate volume) and normalized headspace C gas concentration was both positive and reasonably large (r  =  0.44), suggesting that the former may be a factor that influences SHR. The overall transition probabilities between OM and pore voxels were between 0.07 and 0.17, smaller than those used in previous simulation studies. We computed the length scales over which OM, pore and mineral phases vary within each aggregate using 3-D indicator variograms. The median range of models fitted to variograms of OM varied between 38 and 175 µm and was generally larger than the other two phases within each aggregate, but in general variogram models had ranges <  250 µm. There was no evidence to support the hypotheses concerning scales of variation in OM and magnitude of SHR; the linear correlation was 0.01. There was weak evidence to suggest a statistical relationship between voxel-based OM–pore transition probabilities and the magnitudes of aggregate SHR (r  =  0.12). We discuss how our analyses could be extended and suggest improvements to the approach we used.

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