Synchrotron X-ray Microtomography Research Articles

X-ray synchrotron microtomography: a new technique for characterizing chrysotile asbestos

Over the last decades, many studies have been conducted on rocks containing Naturally Occurring Asbestos (NOA) to determine the potential health risks to exposed neighboring populations. It is difficult to accurately characterize the asbestos fibres contained within the rocks as conventional techniques are not effective and have drawbacks associated with the disturbance of the sample under study. X-ray synchrotron microtomography (SR-μCT) supplemented with polarized light microscope (PLM), scanning electron microscopy analysis combined with energy dispersive spectrometry (SEM/EDS), electron probe micro-analysis (EPMA) were used for identifying asbestos fibres in a mineral matrix. As a case study, we analyzed a representative set of veins and fibrous chrysotile that fills the veins, taken from massive serpentinite outcrops (Southern-Italy). We were able to identify respirable chrysotile fibres (regulated asbestos) within the serpentinite matrix. SR-μCT of NOA veins achieved the resolution and reconstructed 3D structures of infill chrysotile asbestos fibres and other phase structures that were not resolvable with PLM, SEM or EPMA. Moreover, due to differences in chemical composition between veins and matrix, the data obtained enabled us to evaluate the vein shapes present in the massive serpentinite matrix. In particular, iron and aluminum distribution variations between veins and matrix induce different radiation absorption patterns thus permitting a detailed image-based 3D geometric reconstruction. The advantages of the SR-μCT technique as well as limitation of conventional methods are also discussed. These analytical approaches will be used for conducting future research on NOA of other minerals, which exhibit asbestiform and non-asbestiform habits within veins, including asbestos amphiboles.

Study of drug particle distributions within mini-tablets using synchrotron X-ray microtomography and superpixel image clustering.

Uniform drug distribution within fast disintegrating tablets is a key quality measure to ensure a reliable, steady, and targeted release of the contained active pharmaceutical ingredients. In this work, the drug particle distribution in mini-tablets was studied with synchrotron phase contrast X-ray microtomography. Mini-tablets had a weight of 9.5mg and a drug load from 2.5% to 20%. Moxidectin, a drug used for treatment of parasitic infections, was used as a model compound. Drug content covered a range from 91% to 121% of the target dose. A linear iterative clustering (SLIC) superpixel method was used for segmentation, analysis, and visualization of the spatial distribution of individual tablet components (i.e., pores, excipients, and drug). Results show that the drug was not uniformly distributed within the tablet, revealing an increasing drug load towards the tablets' outer boundaries and thus indicative of a radial displacement of drug particles during compaction. The presented method can be used for the quantitative analysis of drug content and drug distribution within pharmaceutical tablets, allowing for the optimization of fast disintegrating formulations. The results also affirm that that drug loads up to 20% will not lead to segregation for moxidectin.

Wood identification of Japanese Shinto deity statues in Matsunoo-taisha Shrine in Kyoto by synchrotron X-ray microtomography and conventional microscopy methods

Research on the wood species of Japanese Buddhist statues has an over 60 years’ history and recently many Buddhist “Ichiboku” statues carved out of a single bole made from the Nara to Heian periods were scientifically revealed to be made of Torreya nucifera. Shinto deity statues in Japan, however, have not yet been investigated scientifically. Because many Shinto deity statues are enshrined behind closed doors, there are fewer opportunities to investigate them. To examine the differences and similarities in wood selection between Buddhist and Shinto deity statues, wood identification was conducted on the 11 Shinto deity statues of Matsunoo-taisha Shrine, Kyoto, Japan, using synchrotron X-ray microtomography and conventional microscopy methods. The results indicated two female deity statues with the ink inscriptions indicating the production year of 1143 were of Torreya nucifera, one female deity statue of Zelkova serrata, and the other eight statues, i.e., two female deity statues, four male deity statues and two priestly attire deity statues of Prunus s.l. spp.

Visualization of Failure and the Associated Grain-Scale Mechanical Behavior of Granular Soils under Shear using Synchrotron X-Ray Micro-Tomography.

The rapid development of X-ray imaging techniques with image processing and analysis skills has enabled the acquisition of CT images of granular soils with high-spatial resolutions. Based on such CT images, grain-scale mechanical behavior such as particle kinematics (i.e., particle translations and particle rotations), strain localization and inter-particle contact evolution of granular soils can be quantitatively investigated. However, this is inaccessible using conventional experimental methods. This study demonstrates the exploration of the grain-scale mechanical behavior of a granular soil sample under triaxial compression using synchrotron X-ray micro-tomography (μCT). With this method, a specially fabricated miniature loading apparatus is used to apply confining and axial stresses to the sample during the triaxial test. The apparatus is fitted into a synchrotron X-ray tomography setup so that high-spatial resolution CT images of the sample can be collected at different loading stages of the test without any disturbance to the sample. With the capability of extracting information at the macro scale (e.g., sample boundary stresses and strains from the triaxial apparatus setup) and the grain scale (e.g., grain movements and contact interactions from the CT images), this procedure provides an effective methodology to investigate the multi-scale mechanics of granular soils.

Visualization of Failure and the Associated Grain-Scale Mechanical Behavior of Granular Soils under Shear using Synchrotron X-Ray Micro-Tomography

Visualization of Failure and the Associated Grain-Scale Mechanical Behavior of Granular Soils under Shear using Synchrotron X-Ray Micro-Tomography

The last dicynodont? Re-assessing the taxonomic and temporal relationships of a contentious Australian fossil

Dicynodonts, a lineage of non-mammalian therapsids, who's derived taxa evolved edentulous beaked jaws sporting a pair of caniniform tusks, dominated the herbivorous terrestrial vertebrate fauna for much of the Permian and Triassic periods. Long assumed to have met their demise during the end-Triassic extinction event, the discovery of a fragmentary possible dicynodont in Cretaceous rocks in Queensland Australia, potentially extended the longevity of the lineage by nearly 100 million years. This study reassesses the geological, anatomical and historical aspects of this specimen through museum archival research, detrital zircon geochronology, trace element analysis and x-ray synchrotron microtomography, and present new knowledge regarding its temporal, geographical and biological origins, supporting a late Cenozoic (Pliocene-Pleistocene) mammalian megafaunal affinity for the specimen, resulting in a lack of evidence for post-Triassic survival of dicynodonts.

Experimental Measurement of the Local Current Density in the Vicinity of a Lithium Protrusion: Plating and Stripping

Successful prevention of lithium dendrite growth would enable the use of lithium metal as an anode material in next-generation secondary batteries. Mechanically stiff solid polymer electrolytes have been shown to prolong the life of lithium metal cells by partially suppressing lithium dendrite growth. However, we lack fundamental knowledge about the nature of lithium electrodeposition and stripping as a function of time, as direct observation of this phenomenon is non-trivial. Synchrotron X-ray microtomography was used observe lithium metal plating and stripping through these solid polystyrene-block-poly(ethylene oxide)-LiTFSI electrolyte membranes in the vicinity of lithium protrusions. Local current density was calculated from these experimental measurements and mapped on the top and bottom electrode under conditions of lithium metal plating and stripping. Local current density at one electrode was correlated to local current density at the other electrode and to electrode thickness. We show quantitatively how lithium protrusions are stripped at a faster rate than planar lithium and gain insight into the lithium ion transport governing protruding lithium growth in a cycled lithium metal electrode.

Gamma-irradiation-induced micro-structural variations in flame-retardant polyurethane foam using synchrotron X-ray micro-tomography.

Flame-retardant polyurethane foams are potential packing materials for the transport casks of highly active nuclear materials for shock absorption and insulation purposes. Exposure of high doses of gamma radiation causes cross-linking and chain sectioning of macromolecules in this polymer foam, which leads to reorganization of their cellular microstructure and thereby variations in physico-mechanical properties. In this study, in-house-developed flame-retardant rigid polyurethane foam samples were exposed to gamma irradiation doses in the 0-20 kGy range and synchrotron radiation X-ray micro-computed tomography (SR-µCT) imaging was employed for the analysis of radiation-induced morphological variations in their cellular microstructure. Qualitative and quantitative analysis of SR-µCT images has revealed significant variations in the average cell size, shape, wall thickness, orientations and spatial anisotropy of the cellular microstructure in polyurethane foam.

Fast identification of mineral inclusions in diamondat GSECARS using synchrotron X-ray microtomography, radiography and diffraction.

Mineral inclusions in natural diamond are widely studied for the insight that they provide into the geochemistry and dynamics of the Earth's interior. A major challenge in achieving thorough yet high rates of analysis of mineral inclusions in diamond derives from the micrometre-scale of most inclusions, often requiring synchrotron radiation sources for diffraction. Centering microinclusions for diffraction with a highly focused synchrotron beam cannot be achieved optically because of the very high index of refraction of diamond. A fast, high-throughput method for identification of micromineral inclusions in diamond has been developed at the GeoSoilEnviro Center for Advanced Radiation Sources (GSECARS), Advanced Photon Source, Argonne National Laboratory, USA. Diamonds and their inclusions are imaged using synchrotron 3D computed X-ray microtomography on beamline 13-BM-D of GSECARS. The location of every inclusion is then pinpointed onto the coordinate system of the six-circle goniometer of the single-crystal diffractometer on beamline 13-BM-C. Because the bending magnet branch 13-BM is divided and delivered into 13-BM-C and 13-BM-D stations simultaneously, numerous diamonds can be examined during coordinated runs. The fast, high-throughput capability of the methodology is demonstrated by collecting 3D diffraction data on 53 diamond inclusions from Juína, Brazil, within a total of about 72 h of beam time.

In situ real-time 3D observation of porosity growth during composite part curing by ultra-fast synchrotron X-ray microtomography

The present study reports on an experimental development addressing 3D void growth in epoxy-based carbon fibre-reinforced composites during their curing process. For that purpose and to investigate autoclave condition effects, composites samples were cured according to different curing cycles by using a specially designed device, which was installed on a synchrotron beamline dedicated to ultra-fast X-ray microtomography. Thus, 3D in situ images of the voids evolution could be obtained as a function of time, temperature, pressure, initial water content and resin conversion degree, which are the driving factors of void size evolution during the polymerization cycles. Results confirm the combined roles of humidity and temperature on the porosity growth and highlight the complex shape of the generated bubbles. It is also emphasized that a sharp increase of the applied pressure during the curing cycle instantaneously reduces the pore size. Such results improve the understanding of the cure of composites parts and can finally be used as input data for modelling purpose or for validation of existing models.

Early Compressive Deformation of Closed-Cell Aluminum Foam Based on a Three-Dimensional Realistic Structure.

It is well-known that cell morphology plays a vital role in the mechanical properties of the closed-cell aluminum foam. In this work, a three-dimensional (3D) realistic structure was obtained by using the synchrotron X-ray micro-tomography technique and then translated into a numerical model for a further finite-element simulation. In order to investigate the early compressive deformation in the closed-cell aluminum foam, we chose three different strain levels, namely, 0.2% (initiation of plastic strain), 2.8% (propagation of plastic strain band), and 6% (formation of collapse band) to discuss the evolution forms of plastic strain concentration by simulation. We found that the curvature, anisotropy, and distribution of cell volume of adjacent cells played a vital role in the initiation of plastic strain. Furthermore, the phenomenon that plastic strain band propagated along the direction aligned 45° with respect to the orientation of the compression was also investigated in the propagation of the plastic strain band and formation of the collapse band. Finally, the comparison between experimental results and simulation results was performed to illustrate the early location of these three different levels in the whole compressive deformation.

Supereruption quartz crystals and the hollow reentrants

AbstractHollow reentrants in quartz phenocrysts from Yellowstone (western United States) caldera’s Lava Creek Tuff are preserved vestiges of bubbles in the supereruption’s pre-eruptive magma reservoir. We characterized the reentrants using a combination of petrographic techniques, synchrotron X-ray microtomography, and cathodoluminescence imagery. One or more reentrants occur in ∼20% of quartz, and up to ∼90% of those reentrants are hollow. The earliest-erupted parts of the Lava Creek Tuff have the most empty reentrants. The hollow reentrants provide direct, physical evidence for volatile saturation, exsolution, and retention in a magma reservoir. Quartz-melt surface tension permits bubbles to attach to quartz only when bubbles have been able to nucleate and grow in the melt. Prior to eruption, the Lava Creek Tuff existed as a bubbly, volatile-saturated magma reservoir. The exsolved volatiles increased magma compressibility, helping to prevent the ever-accumulating magma from reaching a critical, eruptive overpressure until it reached a tremendous volume.

3D characterization of ultrasonic melt processing on the microstructural refinement of Al[sbnd]Cu alloys using synchrotron X-ray tomography

The effect of ultrasonic melt processing (USP) on the three-dimensional (3D) architecture of intermetallic phases and pores in two multicomponent cast Al–5.0Cu–0.6Mn–0.5(1.0) Fe alloys is characterized using conventional microscopy and synchrotron X-ray microtomography. The two alloys are found to contain intermetallic phases, such as α-Al15(FeMn)3Cu2, β-Al7Cu2Fe, Al3(FeMn), Al6(FeMn), and Al2Cu, that have complex networked morphology in 3D. The refined and equiaxed microstructures can be obtained by the application of USP. The results show that USP effectively reduce the volume fraction, interconnectivity, and equivalent diameter of the intermetallic phases in both alloys. The grain sizes of 0.5Fe and 1.0Fe alloys are decreased from 16.9 μm and 15.8 μm without USP to 13.3 μm and 12.2 μm with USP, respectively. USP can effectively reduce the volume fraction of pores in both alloys due to the ultrasonic degassing effect. The main refinement mechanisms are fragmentation of primary and secondary dendrites induced by acoustic bubbles and acoustic streaming flow.

Experimental comparison of agent-enhanced flushing for the recovery of crude oil from saturated porous media

The subsurface remediation of nonaqueous liquid (NAPL) has proven to be challenging even when implementing more aggressive enhanced-flushing techniques. The objective of this study was to evaluate the effectiveness of a combination of alkaline- and surfactant-based enhanced flushing for the removal of crude oil (medium fraction) from saturated porous media. Synchrotron X-ray microtomography (SXM) was used to perform pore-scale examination of NAPL fragmentation and changes in blob morphology, and recovery using three different advective flushing methods: surface-active agent (surfactant) flushing, alkaline flushing, and sequential alkaline-surfactant flushing. This set of experiments was conducted to understand effects on such processes (fragmentation and recovery) as a function of media composition (geochemical/mineralogical) and pH alterations due to calcium-carbonate fraction. Results showed that the sequential flushing technique (alkaline→ surfactant) yielded the highest recovery, 32% after 5 pore volumes (PV) of flushing. The crude oil (NAPL) distribution varied due to differences in porous medium mixture composition and type of fluid (i.e. surfactant vs. alkaline) used for flushing. The results of this study can be used to aid in the understanding of physical and chemical parameters/properties that control mobilization of crude oil in saturated porous media. This can help reduce time and cost during remediation of contaminated sites that contain crude oil or less dense NAPL derivatives consistent with fuel-type petroleum hydrocarbons.

Combining in-situ synchrotron X-ray microtomography and acoustic emission to characterize damage evolution in ceramic matrix composites

In-situ synchrotron X-ray microtomography and acoustic emission (AE) were combined to study the behavior of ceramic matrix composite laminates subjected to in-plane tensile or flexural loading at room temperature. A detailed characterization of the initiation and progression of two key damage modes (matrix cracking and fiber breaks) is obtained from microtomography, and the relationship between damage and AE is directly observed. A graphical representation of AE data, which has potential for real-time use, is employed to reveal differences in damage progression due to fiber architecture or loading mode. In addition, strong empirical relationships are observed between matrix crack area and AE energy, as well as between fiber breaks and number of AE events.

MicroX-ray absorption near edge structure tomography reveals cell-specific changes of Zn ligands in leaves of turnip yellow mosaic virus infected plants

As many metals are essential for plants, excess or deficiency of them or alteration of their uptake, translocation, sequestration or physiological use can have severe consequences for plant growth and fitness. Therefore, investigating the distribution and speciation of metals in tissues is essential to understand plant physiology. We present a method based on non-destructive Synchrotron X-ray microtomography combined with microspectroscopy for studying metal distribution and speciation in plant tissues. By using the Maia detector system and the high flux of the undulator beam at the P06 beamline of the PETRA III synchrotron (at DESY), it was possible to record micro X-ray Absorption Near Edge Structure (μXANES) for every voxel of a tomogram. The metal coordination in regions of interest within the tissue samples could be determined by comparing the XANES with spectra of relevant reference compounds. Metal distribution and coordination were measured in shock frozen hydrated plant leaves in a cryostream, avoiding sample preparation artefacts like liquid cell content redistribution that occurs with other preparation methods, unequal distribution of stains in staining assays, sample degradation by beam damage and thawing, etc. A spatial resolution of 5 μm was selected, which is sufficient to resolve all leaf tissues (epidermis, palisade mesophyll, spongy mesophyll, veins), larger cells and biomineralization hotspots.As an application example, we studied the effect of infection with Turnip Yellow Mosaic Virus (TYMV) on the Zn distribution and the Zn speciation in duplicates of Noccaea ochroleucum. This non-accumulator plant grown with 100 μM Zn had enough metal to allow collecting significant spectroscopic data. We found that the TYMV infected samples formed biomineralization crystallites, showing strong spectroscopic similarity to Zn silicate.

Synchrotron tomography of intervertebral disc deformation quantified by digital volume correlation reveals microstructural influence on strain patterns

The intervertebral disc (IVD) has a complex and multiscale extracellular matrix structure which provides unique mechanical properties to withstand physiological loading. Low back pain has been linked to degeneration of the disc but reparative treatments are not currently available. Characterising the disc’s 3D microstructure and its response in a physiologically relevant loading environment is required to improve understanding of degeneration and to develop new reparative treatments. In this study, techniques for imaging the native IVD, measuring internal deformation and mapping volumetric strain were applied to an in situ compressed ex vivo rat lumbar spine segment. Synchrotron X-ray micro-tomography (synchrotron CT) was used to resolve IVD structures at microscale resolution. These image data enabled 3D quantification of collagen bundle orientation and measurement of local displacement in the annulus fibrosus between sequential scans using digital volume correlation (DVC). The volumetric strain mapped from synchrotron CT provided a detailed insight into the micromechanics of native IVD tissue. The DVC findings showed that there was no slipping at lamella boundaries, and local strain patterns were of a similar distribution to the previously reported elastic network with some heterogeneous areas and maximum strain direction aligned with bundle orientation, suggesting bundle stretching and sliding. This method has the potential to bridge the gap between measures of macro-mechanical properties and the local 3D micro-mechanical environment experienced by cells. This is the first evaluation of strain at the micro scale level in the intact IVD and provides a quantitative framework for future IVD degeneration mechanics studies and testing of tissue engineered IVD replacements. Statement of SignificanceSynchrotron in-line phase contrast X-ray tomography provided the first visualisation of native intact intervertebral disc microstructural deformation in 3D. For two annulus fibrosus volumes of interest, collagen bundle orientation was quantified and local displacement mapped as strain. Direct evidence of microstructural influence on strain patterns could be seen such as no slipping at lamellae boundaries and maximum strain direction aligned with collagen bundle orientation. Although disc elastic structures were not directly observed, the strain patterns had a similar distribution to the previously reported elastic network. This study presents technical advances and is a basis for future X-ray microscopy, structural quantification and digital volume correlation strain analysis of soft tissue.

Kinetic Monte Carlo simulation of sintering behavior of additively manufactured stainless steel powder particles using reconstructed microstructures from synchrotron X-ray microtomography

Abstract In this study, the sintering behavior of additively manufactured stainless steel powder particles is simulated using a three-dimensional kinetic Monte Carlo (kMC) model. The initial microstructure of powder particles is reconstructed using micro-CT images from the Argonne National Laboratory’s synchrotron X-ray microtomography facility. Using the model, the sintering characteristics of the powder, including its relative density, neck growth, and grain coarsening, are quantitatively analyzed. Sintering temperature directly affects the rate of densification and grain growth and coarsening. Higher temperature results in faster densification and grain growth. Additionally, the relationship between grain coarsening and densification is analyzed. It is observed that when the relative density is below 0.70, the powder particles undergo densification; whereas when the relative density is higher than 0.70, grain coarsening is the main mechanism.

Yantaromyiidae, a new family of Diptera (Brachycera: Schizophora) from Tertiary Baltic amber and X-ray synchrotron microtomography imaging of its structures

A new monotypic family, †Yantaromyiidae (Insecta, Diptera, Schizophora), is described from Baltic amber. Yantaromyia arcana gen. et sp. nov. is represented by a single well-preserved male. X-ray synchrotron microtomography is used to reveal details of its morphology. The new family is a schizophoran fly, placed here close to Heleomyzidae + Trixoscelididae + Rhinotoridae, and is erected on the basis of the following combination of (supposed) apomorphies with respect to Schizophora: lunule enlarged and bare, male eyes dichoptic, male abdominal segments 6–8 fused and secondarily almost symmetrical, legs strongly setose, tibiae with two preapical setae dorsally, subscutellum strongly convex, thoracic suture perpendicular to the longitudinal body axis and reaching row of dorsocentrals. Additional characters include: inclinate frontal setae absent, postocellars convergent, frontal vitta setulose, postsutural intraalar absent, anepisternum without strong setae, anepimeron bare, both proepisternal and proepimeral setae present. Microtomography revealed that some cuticular remains are present, displaced and, if occasionally occurring close to the body surface, visible as false pits.http://zoobank.org/urn:lsid:zoobank.org:pub:6C6EF7FF-74CF-4775-A433-B2E850015B74

A pore-scale investigation of heavy crude oil trapping and removal during surfactant-enhanced remediation

The presence of nonaqueous phase liquid (NAPL) in the subsurface presents significant challenges for soil and groundwater remediation. In particular, heavy crude oil, coal tar and/or bitumen present unique difficulties for removal and cleanup due to associated high viscosities, low aqueous solubilities, and limited mobility extraction potential. Although surfactant-enhanced aquifer remediation (SEAR) techniques have shown some promise for source removal, overall remediation (mobilization) performance will depend significantly on interfacial effects between the fluid and solid phases. A pore-scale study, implementing synchrotron X-ray microtomography (SXM), was conducted to understand and quantify the trapping and mobilization mechanisms and in-situ emulsification processes of heavy crude oil distributed within increasing complexity (i.e. physical heterogeneity) unconsolidated sands during surfactant flushing events. Pore-scale imaging analyses were conducted to quantify the changes in oil blob morphology before and after surfactant flushing events to assess the primary factors controlling the recovery. Results showed relatively low (10%) net recovery from the homogeneous sand after 5 pore volumes (PVs) of surfactant flushing and may be, in part, due to the more connected ganglia (i.e. single continuous) oil-phase. Such a condition may have limited the surfactant/oil contact resulting in relatively low interfacial activity and correspondingly inefficient oil mobilization and recovery. Negligible net oil recovery was achieved from the mildly-heterogeneous-sand and is likely due to the lower associated permeability of this particular porous medium. Furthermore, the oil-phase distribution within this medium primarily consisted of small disconnected blobs more readily exposed (in contact with) the surfactant solution. For the highly-heterogeneous-sand experiments, an average of 20% heavy-oil recovery resulted after each flushing event (total of ~37% after 5 PVs) and was attributed to more efficient reduction of interfacial tension associated with the increased surfactant-oil contact. The associated higher pH sand/fine‑carbonate system may have aided in maintaining a water-wet porous medium, a condition more conducive to higher oil recovery and displacement efficiency.