ABSTRACT A dedicated micro-CT beamline is planned for the Australian Synchrotron which will exten... more ABSTRACT A dedicated micro-CT beamline is planned for the Australian Synchrotron which will extend the synchrotron's imaging and tomography capability down to the smaller scale, incorporating phase-contrast and absorption-contrast, and an additional focussing-based mode for high-resolution. The beamline will use multi-layer mirror monochromators for enhanced flux, and will focus particularly on dynamic and high throughput studies in both monochromatic and pink-beam mode. Together with the existing Imaging and Medical beamline, this beamline will produce numerous large datasets of 10 GB or more, providing a significant data-processing challenge. The Remote-CT project addresses this by combining the "MASSIVE" supercomputing GPU cluster with XLI / X-TRACT software, developed at CSIRO. This software has extensive functionality for both processing and simulation of absorption and phase-contrast tomography data and has now been modified for parallel operation on a GPU cluster to take maximum advantage of the speed-up this enables.
The usefulness of zinc oxide (ZnO) nanoparticles has led to their wide distribution in consumer p... more The usefulness of zinc oxide (ZnO) nanoparticles has led to their wide distribution in consumer products, despite only a limited understanding of how this nanomaterial behaves within biological systems. From a nanotoxicological viewpoint the interaction(s) of ZnO nanoparticles with cells of the immune system is of specific interest, as these nanostructures are readily phagocytosed. In this study, rapid scanning X-ray fluorescence microscopy was used to assay the number ZnO nanoparticles associated with ∼1000 individual THP-1 monocyte-derived human macrophages. These data showed that nanoparticle-treated cells endured a 400% elevation in total Zn levels, 13-fold greater than the increase observed when incubated in the presence of an equitoxic concentration of ZnCl2. Even after excluding the contribution of internalized nanoparticles, Zn levels in nanoparticle treated cells were raised ∼200% above basal levels. As dissolution of ZnO nanoparticles is critical to their cytotoxic respons...
London 2013, 75th eage conference en exhibition incorporating SPE Europec, 2013
ABSTRACT Nowadays the carbonate rocks are attracting growing interest as a possible site for CO2 ... more ABSTRACT Nowadays the carbonate rocks are attracting growing interest as a possible site for CO2 geo-sequestration. Monitoring of the injected carbon dioxide is generally an important part of any sequestration project. CO2 is known to change the properties of the hosting rocks and to affect the reservoir characteristics - elastic moduli, reservoir capacity, etc. Thus, predicting changes in microstructures and elastic properties of carbonate rocks after the CO2 injection is of great importance. In the current work we study the effects of sc-CO2 injection on microstructure and elastic properties of carbonate rock. We use microtomographic images of two Savonniere limestone samples, one in its natural state and one after injecting sc-CO2. A statistical analysis exhibits that the injection of sc-CO2 has led to the increase in porosity and changes of the microstructure of the carbonate sample. It has resulted in the increase of the average volume of individual pores and the decrease of the total number of pores. The CO2 injection has increased the mean radii of pore throats, has raised length of pore network segments and makes orientation distribution of meso-pores more isotropic. These changes in microstructure have been reflected in lower numerically simulated elastic moduli of the sample.
ABSTRACT This paper outlines the data-constrained microstructure modelling (DCM) approach to dete... more ABSTRACT This paper outlines the data-constrained microstructure modelling (DCM) approach to determine microscopic distributions of pores (voids), quartz and calcite in sandstone. The DCM model incorporates two computed-tomography (CT) data sets as constraints acquired at X-ray beam energies of 35 keV and 45 keV. The DCM predicted 3D microstructure is consistent with SEM observations that calcite exists in the sandstone as aggregates comparable to the size of the quartz grains, or as attachments to the surface of quartz grains. Using DCM, it was possible to detect the existence of a significant proportion of the pores whose sizes were smaller than the X-ray CT resolution. The DCM predicted overall porosity has shown a reasonable agreement with the value obtained from helium gas measurements, which is a significant improvement from predictions made by the more traditional image segmentation techniques. The capability to characterise the 3D microscopic numerical representations of pores and mineral compositions enables more accurate pore structural characterisation and computations of permeability and various other physical properties of interest for reservoir sandstones for the purpose of petroleum exploration and production.
ABSTRACT The three-dimensional distribution of the materials composing a sample is reconstructed ... more ABSTRACT The three-dimensional distribution of the materials composing a sample is reconstructed using multiple-energy computed tomography techniques. The a priori knowledge about the specific materials that are present in the sample is used for decomposing the measured intensity projections into projected thicknesses of each component material. Those decomposed projections are then processed using iterative reconstruction algorithms to separately obtain the three-dimensional distribution of each material. A new iterative reconstruction algorithm has been implemented and its performance is compared to the standard filtered back projection and to another existing iterative algorithm based on histogram manipulation. The method is first tested with simulations on data for a realistic, three-materials' numerical sample and then applied to experimental micro-tomography data. The accuracy of the reconstruction from experimental data is tested by means of an energy dispersive x-ray spectroscopy scan of the sample.
ABSTRACT X-ray Microtomography bridges the 3D analysis gap between conventional x-ray tomography ... more ABSTRACT X-ray Microtomography bridges the 3D analysis gap between conventional x-ray tomography and TEM tomography. The use of a laboratory-based microfocus source opens up the opportunity to gain additional benefits from in-line phase contrast for enhancing the visibility of fine features, cracks, voids and boundaries in individual views. Coupled with phase retrieval methods, such images can be used as input to conventional reconstruction algorithms for three dimensional visualization. Working at high resolution brings challenges of physical stability of the system. Software approaches to overcoming these difficulties have enabled submicron resolution 3D reconstructions.
A method is presented for quantitative phase-contrast tomography using unfiltered radiation from ... more A method is presented for quantitative phase-contrast tomography using unfiltered radiation from a small polychromatic source. The three-dimensional distribution of complex refractive index in a monomorphous object is reconstructed given a single projection image per view angle. The reconstruction algorithm is achromatic and stable with respect to high-spatial-frequency noise, in contrast to conventional tomography. The density distribution in a test
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2014
This review provides a brief overview, albeit from a somewhat personal perspective, of the evolut... more This review provides a brief overview, albeit from a somewhat personal perspective, of the evolution and key features of various hard X-ray phase-contrast imaging (PCI) methods of current interest in connection with translation to a wide range of imaging applications. Although such methods have already found wide-ranging applications using synchrotron sources, application to dynamic studies in a laboratory/clinical context, for example for in vivo imaging, has been slow due to the current limitations in the brilliance of compact laboratory sources and the availability of suitable high-performance X-ray detectors. On the theoretical side, promising new PCI methods are evolving which can record both components of the phase gradient in a single exposure and which can accept a relatively large spectral bandpass. In order to help to identify the most promising paths forward, we make some suggestions as to how the various PCI methods might be compared for performance with a particular view to identifying those which are the most efficient, given the fact that source performance is currently a key limiting factor on the improved performance and applicability of PCI systems, especially in the context of dynamic sample studies. The rapid ongoing development of both suitable improved sources and detectors gives strong encouragement to the view that hard X-ray PCI methods are poised for improved performance and an even wider range of applications in the near future.
ABSTRACT A dedicated micro-CT beamline is planned for the Australian Synchrotron which will exten... more ABSTRACT A dedicated micro-CT beamline is planned for the Australian Synchrotron which will extend the synchrotron's imaging and tomography capability down to the smaller scale, incorporating phase-contrast and absorption-contrast, and an additional focussing-based mode for high-resolution. The beamline will use multi-layer mirror monochromators for enhanced flux, and will focus particularly on dynamic and high throughput studies in both monochromatic and pink-beam mode. Together with the existing Imaging and Medical beamline, this beamline will produce numerous large datasets of 10 GB or more, providing a significant data-processing challenge. The Remote-CT project addresses this by combining the "MASSIVE" supercomputing GPU cluster with XLI / X-TRACT software, developed at CSIRO. This software has extensive functionality for both processing and simulation of absorption and phase-contrast tomography data and has now been modified for parallel operation on a GPU cluster to take maximum advantage of the speed-up this enables.
The usefulness of zinc oxide (ZnO) nanoparticles has led to their wide distribution in consumer p... more The usefulness of zinc oxide (ZnO) nanoparticles has led to their wide distribution in consumer products, despite only a limited understanding of how this nanomaterial behaves within biological systems. From a nanotoxicological viewpoint the interaction(s) of ZnO nanoparticles with cells of the immune system is of specific interest, as these nanostructures are readily phagocytosed. In this study, rapid scanning X-ray fluorescence microscopy was used to assay the number ZnO nanoparticles associated with ∼1000 individual THP-1 monocyte-derived human macrophages. These data showed that nanoparticle-treated cells endured a 400% elevation in total Zn levels, 13-fold greater than the increase observed when incubated in the presence of an equitoxic concentration of ZnCl2. Even after excluding the contribution of internalized nanoparticles, Zn levels in nanoparticle treated cells were raised ∼200% above basal levels. As dissolution of ZnO nanoparticles is critical to their cytotoxic respons...
London 2013, 75th eage conference en exhibition incorporating SPE Europec, 2013
ABSTRACT Nowadays the carbonate rocks are attracting growing interest as a possible site for CO2 ... more ABSTRACT Nowadays the carbonate rocks are attracting growing interest as a possible site for CO2 geo-sequestration. Monitoring of the injected carbon dioxide is generally an important part of any sequestration project. CO2 is known to change the properties of the hosting rocks and to affect the reservoir characteristics - elastic moduli, reservoir capacity, etc. Thus, predicting changes in microstructures and elastic properties of carbonate rocks after the CO2 injection is of great importance. In the current work we study the effects of sc-CO2 injection on microstructure and elastic properties of carbonate rock. We use microtomographic images of two Savonniere limestone samples, one in its natural state and one after injecting sc-CO2. A statistical analysis exhibits that the injection of sc-CO2 has led to the increase in porosity and changes of the microstructure of the carbonate sample. It has resulted in the increase of the average volume of individual pores and the decrease of the total number of pores. The CO2 injection has increased the mean radii of pore throats, has raised length of pore network segments and makes orientation distribution of meso-pores more isotropic. These changes in microstructure have been reflected in lower numerically simulated elastic moduli of the sample.
ABSTRACT This paper outlines the data-constrained microstructure modelling (DCM) approach to dete... more ABSTRACT This paper outlines the data-constrained microstructure modelling (DCM) approach to determine microscopic distributions of pores (voids), quartz and calcite in sandstone. The DCM model incorporates two computed-tomography (CT) data sets as constraints acquired at X-ray beam energies of 35 keV and 45 keV. The DCM predicted 3D microstructure is consistent with SEM observations that calcite exists in the sandstone as aggregates comparable to the size of the quartz grains, or as attachments to the surface of quartz grains. Using DCM, it was possible to detect the existence of a significant proportion of the pores whose sizes were smaller than the X-ray CT resolution. The DCM predicted overall porosity has shown a reasonable agreement with the value obtained from helium gas measurements, which is a significant improvement from predictions made by the more traditional image segmentation techniques. The capability to characterise the 3D microscopic numerical representations of pores and mineral compositions enables more accurate pore structural characterisation and computations of permeability and various other physical properties of interest for reservoir sandstones for the purpose of petroleum exploration and production.
ABSTRACT The three-dimensional distribution of the materials composing a sample is reconstructed ... more ABSTRACT The three-dimensional distribution of the materials composing a sample is reconstructed using multiple-energy computed tomography techniques. The a priori knowledge about the specific materials that are present in the sample is used for decomposing the measured intensity projections into projected thicknesses of each component material. Those decomposed projections are then processed using iterative reconstruction algorithms to separately obtain the three-dimensional distribution of each material. A new iterative reconstruction algorithm has been implemented and its performance is compared to the standard filtered back projection and to another existing iterative algorithm based on histogram manipulation. The method is first tested with simulations on data for a realistic, three-materials' numerical sample and then applied to experimental micro-tomography data. The accuracy of the reconstruction from experimental data is tested by means of an energy dispersive x-ray spectroscopy scan of the sample.
ABSTRACT X-ray Microtomography bridges the 3D analysis gap between conventional x-ray tomography ... more ABSTRACT X-ray Microtomography bridges the 3D analysis gap between conventional x-ray tomography and TEM tomography. The use of a laboratory-based microfocus source opens up the opportunity to gain additional benefits from in-line phase contrast for enhancing the visibility of fine features, cracks, voids and boundaries in individual views. Coupled with phase retrieval methods, such images can be used as input to conventional reconstruction algorithms for three dimensional visualization. Working at high resolution brings challenges of physical stability of the system. Software approaches to overcoming these difficulties have enabled submicron resolution 3D reconstructions.
A method is presented for quantitative phase-contrast tomography using unfiltered radiation from ... more A method is presented for quantitative phase-contrast tomography using unfiltered radiation from a small polychromatic source. The three-dimensional distribution of complex refractive index in a monomorphous object is reconstructed given a single projection image per view angle. The reconstruction algorithm is achromatic and stable with respect to high-spatial-frequency noise, in contrast to conventional tomography. The density distribution in a test
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2014
This review provides a brief overview, albeit from a somewhat personal perspective, of the evolut... more This review provides a brief overview, albeit from a somewhat personal perspective, of the evolution and key features of various hard X-ray phase-contrast imaging (PCI) methods of current interest in connection with translation to a wide range of imaging applications. Although such methods have already found wide-ranging applications using synchrotron sources, application to dynamic studies in a laboratory/clinical context, for example for in vivo imaging, has been slow due to the current limitations in the brilliance of compact laboratory sources and the availability of suitable high-performance X-ray detectors. On the theoretical side, promising new PCI methods are evolving which can record both components of the phase gradient in a single exposure and which can accept a relatively large spectral bandpass. In order to help to identify the most promising paths forward, we make some suggestions as to how the various PCI methods might be compared for performance with a particular view to identifying those which are the most efficient, given the fact that source performance is currently a key limiting factor on the improved performance and applicability of PCI systems, especially in the context of dynamic sample studies. The rapid ongoing development of both suitable improved sources and detectors gives strong encouragement to the view that hard X-ray PCI methods are poised for improved performance and an even wider range of applications in the near future.
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