X-ray micro-CT Imaging Research Articles

First description of male genital sclerites and associated musculature for two members of Coniopterygidae (Insecta: Neuropterida: Neuroptera) based on X-ray microCT imaging

Coniopterygidae are the dwarfs among the Neuroptera. Despite their miniaturisation, the males are equipped with genital sclerites that are excessively heterogeneous. They function in copulation and sperm transfer and have been widely utilized for species identification, as well being considered of high phylogenetic relevance. The present study is the first to describe the musculature associated with the genital sclerites of two species of Coniopterygidae, Helicoconis lutea (Wallengren, 1871) (Aleuropteryginae), and Coniopteryx pygmaea (Enderlein, 1906) (Coniopteryginae) based on X-ray microCT imaging. We found six pairs of muscles associated with the genital sclerites in H. lutea and seven in C. pygmaea. The images depict other internal organs of the posterior abdominal segments, such as gonads and alimentary canal. In both investigated species, the internal sclerites support the ductus ejaculatorius, which – surprisingly – turned out to be a landmark for the identification of closely adjacent internal sclerites and associated musculature. The interpretation of these sclerites as gonocoxites and gonapophyses of the tenth segment (traditionally denoted as parameres and penis) could be corroborated. Thus it is no longer tenable to assert that possession of a “penis” is exclusive to Coniopterygidae, since this sclerite is part of the ground pattern in Neuroptera. Interactions of genital sclerites and corresponding musculature during copulation are discussed.

The visible skeleton 2.0: phenotyping of cartilage and bone in fixed vertebrate embryos and foetuses based on X-ray microCT.

For decades, clearing and staining with Alcian Blue and Alizarin Red has been the gold standard to image vertebrate skeletal development. Here, we present an alternate approach to visualise bone and cartilage based on X-ray microCT imaging, which allows the collection of genuine 3D data of the entire developing skeleton at micron resolution. Our novel protocol is based on ethanol fixation and staining with Ruthenium Red, and efficiently contrasts cartilage matrix, as demonstrated in whole E16.5 mouse foetuses and limbs of E14 chicken embryos. Bone mineral is well preserved during staining, thus the entire embryonic skeleton can be imaged at high contrast. Differences in X-ray attenuation of ruthenium and calcium enable the spectral separation of cartilage matrix and bone by dual energy microCT (microDECT). Clearing of specimens is not required. The protocol is simple and reproducible. We demonstrate that cartilage contrast in E16.5 mouse foetuses is adequate for fast visual phenotyping. Morphometric skeletal parameters are easily extracted. We consider the presented workflow to be a powerful and versatile extension to the toolkit currently available for qualitative and quantitative phenotyping of vertebrate skeletal development.

3D imaging of bean seeds: Correlations between hilum region structures and hydration kinetics

X-ray micro-CT imaging has been applied successfully in food science and seed research due to its capacity to provide very small details of seed traits that are very complex to score. The micropyle and the tissues of the hilum region of bean seeds are recognized as structures which play an important role in hydration process. This latter influences, in turn, not only germination but also the cooking and industrial processing. Nevertheless, the role of each structure of the bean seeds is yet to be fully understood. Moreover such traits are never been quantified by using 3D imaging approaches.In this work, seeds of four ancient Italian landraces of beans have been scanned by X-ray microCT with a twofold approach: bulk scans for whole seed imaging and single seed scans for internal traits measurements. Then water uptake tests have been performed. The different structures composing the hilum region of the beans have been imaged and characterized. The two-dimensional and the three-dimensional morphometric traits have been correlated with parameters of hydration models by Principal Component Analysis (PCA) and Pearson coefficients.Micropyle groove area was the trait most influencing the very initial hydration rates while the hilum groove area was the best correlated with the overall infiltration behavior. The internal free space was the trait best correlated with the moisture at equilibrium. Moreover, strophiole shape resulted the most suitable internal trait for univocal identification of the four landraces.Overall results give a contribution to the understanding of the role of hilum region structures in bean seeds hydration process and show novel morphological traits useful for identification of local bean landraces.

Modeling of multiple phase solid microstructures and prediction of mechanical behaviors of foamed concrete

Mechanical behaviors of foamed concrete, which is a cellular lightweight binder with entrained air voids, are evaluated using the phase field fracture model in a finite element framework. A methodology to identify the micro-scale material properties/parameters of the foamed concrete to predict their macro-scale mechanical behaviors is presented. Multiple phase solid virtual specimens are obtained from the analysis of X-ray micro-CT images, and the input material modeling parameters for the corresponding phases are identified through a series of calibration processes. The similarities and differences in mechanical responses, including stress vs. strain relations and crack patterns from single and multiple phase solid microstructures, are analyzed. The multiple phase solid model shows great potential for enabling detailed analyses of the mechanical behaviors of foamed concrete. With further investigations involving calibrations of the input material modeling parameters using more detailed experiments, the proposed framework is found to be a promising choice for supplementing time- and effort-intensive real experiments.

Sparse-view statistical image reconstruction with improved total variation regularization for X-ray micro-CT imaging

Sparse-view x-ray micro computed tomography (micro-CT) reconstruction algorithms via total variation (TV) optimize the data without introducing notable noise and artifacts, resulting in significant scanning time reduction while maintaining image quality. However, due to the piecewise constant assumption for the image, a conventional TV minimization often suffers from patchy artifacts in reconstructed images. Moreover, for lack of directional gradient in TV some directional information are lost. To obviate these drawbacks, in this study we develop a penalized weighted least-square (PWLS) strategy for micro-CT sparse-view image reconstruction by incorporating an adaptive weighted total variation in combination with an adaptive weighted diagonal total variation (AwTV+AwDTV) penalty term. The AwTV considers the vertical and horizontal gradients while the AwDTV uses the diagonal gradients. The associated weights which are defined based on the anisotropic edge properties of an image, are expressed as an exponential function and can be adaptively adjusted by the amount of the difference between voxel intensities to preserve the edge details. To evaluate the presented (AwTV+AwDTV)-PWLS algorithm, both qualitative and quantitative studies were performed by computer simulations and micro-CT data experiments. The Shepp-Logan phantom for computer simulation and the micro-CT water phantom and a rat skull for micro-CT experiments are employed to perform image reconstruction. To evaluate the performance of AwTV+AwDTV algorithm, we compared it with TV and AwTV reconstruction algorithms. The simulation results show that the presented (AwTV+AwDTV)-PWLS algorithm can achieve the lowest RMSE and highest PSNR, SSIM and MTF for different number of projections as compared to the AwTV and conventional TV algorithms. The micro-CT data results confirmed the superiority of the proposed (AwTV+AwDTV) method to the AwTV and TV methods for different number of projections.

Evaluation of the conventional and synchrotron X-ray tomography applied to heterogeneous oil reservoir rocks

Carbonate and sandstone reservoirs play an important role in oil industry as they host over 50% of the world’s hydrocarbon reserves. For an accurately assessment of porosity and pore size distribution of such complex pore-network, which affect directly the macroscopic characteristics of multiphase fluid flow, X-ray computed microtomography (micro-CT) emerges as a powerful tool. In contrast to lab-based X-ray micro-CT (XCT), synchrotron X-ray micro-CT (SXCT) images are commonly free of artefacts (i.e. beam hardening) and the unique properties of synchrotron sources enable the X-ray imaging of complex and heterogeneous materials in greater detail, with higher quality, and short acquisition time. This work reports results of cone beam computed microtomography (XCT) in comparison with synchrotron computed microtomography (SXCT) applied to very heterogeneous carbonate and sandstone reservoir rocks. We analyze the quality of the image generated in terms of detection of details and artefacts, the advantages and limitation of each technique, as well as features like contrast, sharpness, and signal-to-noise ratio (SNR). Although SXCT offers significant advantages over XCT, the latter gains in cost of operation, accessibility and user-friendliness.

Study of plant remains from a fluvial shellmound (Monte Castelo, RO, Brazil) using the X-ray MicroCT imaging technique

This work applies the X-ray MicroCT imaging technique to discuss the identification and preservation/disturbance conditions of plant remains from the Monte Castelo archaeological site, in Brazil's southwestern Amazonia. A preliminary hypothesis based on external morphological traits and the presence of typical starch grains, associates these materials to the Poaceae caryopsis. Moreover, based on their well-preserved non-charred aspect, mineralization was considered as a possible in-situ preservation process. Data from the X-ray computed microtomography (MicroCT) analysis showed that the internal anatomy of the samples corresponds to another type of fruit, described as a small drupe sharing characters with some Anacardiaceae fruits. Additionally, all studied specimens contain a number of exogenous organic and inorganic elements suggesting the action of some disturbance processes on the Monte Castelo plant material.

X-ray Computed Tomography for Characterization of Expanded Polystyrene (EPS) Foam.

Expanded polystyrene (EPS) foam is widely used in building and construction applications for thermal and acoustic insulation. This material is nearly transparent for X-rays, making it difficult to characterize its pore structure in 3D with X-ray tomography. Because of this difficulty, the pore network is often not investigated and is, thus, poorly known. Since this network controls different physical properties, such as the sound absorption, it is crucial to understand its overall structure. In this manuscript, we show how to reveal the pore network of EPS foams through the combination of high resolution X-ray tomography (micro-CT) and saturation techniques. The foams were saturated with CsCl-brine, which acts as a contrasting agent in X-ray micro-CT imaging. This allowed us to separate the beads, making up the foam, from the pore network. Based on the 3D micro-CT results, we were able to assess a representative elementary volume for the polystyrene, which allows for calculating the acoustical parameters from the Johnson–Champoux–Allard (JCA) model, the pore and bead size distribution. The 3D data was also used as input to simulate sound absorption curves. The parametric study showed that an increase in the bead size influenced the sound absorption of the material. We showed that, by doubling the diameter of beads, the absorption coefficient was doubled in certain ranges of frequency.

Fracture evolution in concrete compressive fatigue experiments based on X-ray micro-CT images

This study examines the fatigue performance of plain concrete specimens under uniaxial compression. The experimental program was developed for investigating the fracture evolution in concrete cubic specimens subjected to cyclic compression using the advanced X-ray micro-computed tomography system SkyScan 1173. As compared to other experiments, the 3D micro-CT damage images were shown for a various number of loading cycles. The quantitative evolution of the cracking volume with increasing fatigue damage revealed a strongly non-linear shape. The increase of the total crack volume was higher by 30% as compared to the monotonic fatigue test.

Quantifying static and dynamic stiffness anisotropy and nonlinearity in finely laminated shales: Experimental measurement and modeling

Sedimentary rocks contain layers and a wide range of microstructures that may produce mechanical complexities including dynamic and quasistatic stiffness anisotropy and nonlinearity. However, most applications in geophysics and geomechanics disregard these mechanical complexities, which can lead to significant error and uncertainty in rock properties and may increase the risk associated with cost-intensive drilling and completions operations in shales. We have conducted simultaneous triaxial stress tests and ultrasonic wave propagation monitoring to measure and model stiffness anisotropy and nonlinearity of Mancos Shale plugs with varying bedding orientations. Results highlight the need for different sets of nonlinear coefficients to describe different stress loading paths, in which isotropic loading exhibits larger increases in stiffness for a given change in mean stress (and strain) than deviatoric loading. The vertical transverse isotropic (VTI) nonlinear model helps to account for the appreciable anisotropy and nonlinearity of Mancos samples, in which the dynamic Young’s moduli [Formula: see text] are more than 25% higher than [Formula: see text] and [Formula: see text] increases by approximately 35% during deviatoric stress loading. Measured static moduli are typically less than 50% of their dynamic equivalent and exhibit separate anisotropic and nonlinear relationships. Therefore, we have developed anisotropic stress-dependent dynamic-static transforms to estimate the static moduli from the nonlinear VTI model. Although heterogeneity and discontinuities cause samples to deviate from VTI symmetry, our modified dynamic-static transforms provide an excellent fit to the experimentally measured Young’s moduli and Poisson’s ratios. Post-test X-ray micro-CT imaging evidences the impact of sample layering and heterogeneity on rock failure and failure geometry. Bedding planes can act as preferential failure planes, whereas layering-induced mechanical stratigraphy can cause fractures to reorient due to changes in lithology. Our combined experimental, modeling, and imaging results provide insight into the complex deformational and failure behavior of shales. The analysis and results also highlight the need to consider the elastic and plastic deformations in shales.

High resolution X-ray micro-CT imaging of fibrin scaffold using large area single photon counting detector

This paper deals with the high resolution X-ray micro-computed tomographical (micro-CT) visualization of a fibrin scaffold intended to be used during medical repairs of various types of human tissue. Due to the cellular nature of scaffolds, it is important to inspect their microstructure in high detail on a volumetric basis. In this work, we demonstrate the micro-CT measurement of a fibrin-based bone scaffold performed using a proprietarily developed tomographical scanner equipped with a large-area imaging device (LAD) composed of 10× 10 Timepix silicon pixel detectors without any gaps between the individual tiles. The fibrin scaffolds are based on organic materials, which may be reinforced by various additives to improve their mechanical characteristics, and their dimensions are generally very small (i.e. micrometer to millimeter scale). As the organic material used in fibrin scaffolds exhibits very low X-ray attenuation, low-energy X-ray radiation is desirable to achieve sufficient contrast in the projections. Moreover, a high resolution is needed to visualize the fine features in the scaffolds. Here, conventional scintillation detectors suffer two problems that make the aforementioned LAD superior for the imaging of the investigated scaffolds: a wide point-spread function and low sensitivity at low energies. Despite the high LAD sensitivity to low-energy photons, it was necessary to apply several correction procedures to achieve the highest possible resolution. Here, a computational procedure was developed to compensate for the drift of the tube's focal spot, geometrical imperfections of the LAD detector assembly, and the effects of its border pixels with different responses and sizes. We demonstrate the results on the final reconstructed images based on uncorrected and corrected projections, where we achieved a 1 μm voxel size.

Changes in xylem conducting capacity and water storage across species: how can variable air content of xylem cells affect sap flow?

Sap flow sensors and other techniques are commonly used across species and plant organs to quantify water use and storage, detect stress, and evaluate the contribution of various tissues to plant/organ water balance. Sap flow methods often rely upon modelling or assumptions about how heat delivered by the sap flow sensors is partitioned into convection and conduction into active sapwood xylem and surrounding tissues. Dynamic changes in tissue water content over space and time can impact the interpretation of plant and organ water use and how various compartments contribute to an integrated response to plant stress. Here, we first summarize results from a variety of studies that used a combination of synchrotron-based X-ray microCT and MRI imaging to demonstrate how water content of various organs and xylem cell types can change temporally and how the spatial distribution of air-filled tissue may impact patterns of sap flow within the xylem network. Results from visualization techniques were compared to that from traditional hydraulic and sap flow methods to illustrate potential discrepancies particularly when comparing data from excised stems versus intact plants. Using a spatially explicit model, we demonstrate how changes in the water content of various cell types can impact resulting interpretation of sensor output. Implications for the interpretation of sap flow and other sensor data based on these results is discussed.

The Xerobranching Response Represses Lateral Root Formation When Roots Are Not in Contact with Water

Efficient soil exploration by roots represents an important target for crop improvement and food security [1, 2]. Lateral root (LR) formation is a key trait for optimizing soil foraging for crucial resources such as water and nutrients. Here, we report an adaptive response termed xerobranching, exhibited by cereal roots, that represses branching when root tips are not in contact with wet soil. Non-invasive X-ray microCT imaging revealed that cereal roots rapidly repress LR formation as they enter an air space within a soil profile and are no longer in contact with water. Transcript profiling of cereal root tips revealed that transient water deficit triggers the abscisic acid (ABA) response pathway. In agreement with this, exogenous ABA treatment can mimic repression of LR formation under transient water deficit. Genetic analysis in Arabidopsis revealed that ABA repression of LR formation requires the PYR/PYL/RCAR-dependent signaling pathway. Our findings suggest that ABA acts as the key signal regulating xerobranching. We conclude that this new ABA-dependent adaptive mechanism allows roots to rapidly respond to changes in water availability in their local micro-environment and to use internal resources efficiently.

Spatially offset Raman spectroscopy for in vivo bone strength prediction.

Bone strength is a worldwide health concern. Although multiple techniques have been developed to evaluate bone quality, there are still gaps to be filled. Here we report a non-invasive approach for the prediction of bone strength in vivo using spatially offset Raman spectroscopy. Raman spectra were acquired transcutaneously from the tibiae of mice from 4 to 23 weeks old and subsequently on the exposed bones. Partial least squares regression was applied to generate predictions of the areal bone mineral density (aBMD), volumetric bone mineralization density (vBMD), and maximum torque (MT) of each tibia as quantified by dual-energy X-ray absorptiometry, microCT imaging, and biomechanical tests, respectively. Significant correlations were observed between Raman spectral predictions and the reference values in all three categories. To our knowledge, this is the first demonstration of Raman spectroscopy predicting a biomechanical bone parameter (MT) in vivo with an uncertainty much smaller than the spread in the reference values.

Reliability-based design optimization of composite battery box based on modified particle swarm optimization algorithm

The application of carbon fiber reinforced polymer (CFRP) material introduces great challenges to the optimization design process, such as complex non-linear material behavior, the inherent uncertainty of design variables and multilevel characteristics of the structure. This paper aims at developing a reliability-based design optimization (RBDO) method to solve the CFRP battery box lightweight design problem considering both meso- and macro-scopic parameters. The method has three kernel parts: the uncertainty quantification and propagation part, the finite element analysis part and the optimization part. In the first part, the internal geometry variability of plain woven CFRP was obtained by X-ray micro-CT images. Representative Volume Element (RVE) models are established to predict the elastic and strength properties of the studied composites, and the constitutive model of material was adapted in stiffness and strength analysis of the battery box structure in the second part. Then a RBDO procedure considering design variables across two scales is developed using a modified particle swarm optimization and surrogate modeling techniques. The structure of the CFRP battery box achieved by the proposed multiscale optimization procedure realizes a weight loss of 22.14%, and the performance demands are satisfied with high reliability, which further reveals the advantages of using this methodology.

Non-standard experimental tests of sandstone and its pre-cracking for fracture testing

The paper presents a methodology for investigating fracture phenomena in sandstone. It shows the preparation of test specimens with a cyclic loading generated crack, control of the test specimen preparation and verification by means of x-ray microCT and digital image correlation (DIC) techniques. There are also presented tests studying tensile and fatigue characteristics of arkose sandstone used i. a. for the construction of the medieval Charles Bridge in Prague where weather induced tensile damage and failure occurred. Finally, the new methodology for pre-cracking of the specimens was verified experimentally and fracture toughness was computed.

Thorium-induced Anatomical and Histopathological Changes in Liver of Swiss Mice

Present study is aimed to investigate the anatomical and histopathological changes in liver tissues of Swiss albino male mice, one month after intravenous administration of thorium (232Th; 4 and 40 mg/kg). Synchrotron X-ray micro-CT imaging, CD31 immuno-cytochemistry, hematoxylin & eosin staining and Periodic acid-Schiff staining were performed to study changes in liver anatomy, blood vessels/capillaries, histology and glycogen content of liver, respectively. Synchrotron X-ray micro-CT imaging of liver showed loss of blood vessels in mice treated with thorium (4 mg/kg), which was more prominent at higher dose of thorium (40 mg/kg). These thorium-induced changes in liver were correlated with the decrease in CD31 positive cells and loss of tissue architecture. A dose-dependent increase in glycogen content was also observed in the liver of thorium-treated mice. Our results provide novel insight about the effects of thorium on liver, which may have significant implications in understanding the mechanism of thorium thorium-induced hepatotoxicity.

Rice auxin influx carrier OsAUX1 facilitates root hair elongation in response to low external phosphate

Root traits such as root angle and hair length influence resource acquisition particularly for immobile nutrients like phosphorus (P). Here, we attempted to modify root angle in rice by disrupting the OsAUX1 auxin influx transporter gene in an effort to improve rice P acquisition efficiency. We show by X-ray microCT imaging that root angle is altered in the osaux1 mutant, causing preferential foraging in the top soil where P normally accumulates, yet surprisingly, P acquisition efficiency does not improve. Through closer investigation, we reveal that OsAUX1 also promotes root hair elongation in response to P limitation. Reporter studies reveal that auxin response increases in the root hair zone in low P environments. We demonstrate that OsAUX1 functions to mobilize auxin from the root apex to the differentiation zone where this signal promotes hair elongation when roots encounter low external P. We conclude that auxin and OsAUX1 play key roles in promoting root foraging for P in rice.

Large Ca stable isotopic (δ44/40Ca) variation in a hand-specimen sized spheroidally weathered diabase due to selective weathering of clinopyroxene and plagioclase

Calcium stable isotopic compositions (delta Ca-44/40(SRM 915a)) as well as selected major and trace element concentrations are reported for micro-drilled samples of a hand-specimen sized spheroidally weathered diabase (synonymously used as dolerite or microgabbro) from southern India. A sample of the similar to 2.37 Ga old unweathered diabase (UW) dike was also analyzed. X-ray micro-CT imaging of a representative portion of the weathered sample shows the presence of two dominant mineral phases, plagioclase and clinopyroxene, with minor proportions of an iron-bearing phase (possibly haematite or ilmenite). Two different generations of crosscutting micro-fractures are identified from the micro-CT image. The older fracture is sealed with secondary mineral deposits. The delta Ca-44/40 values of the weathered samples range from 0.42 parts per thousand to 0.84 parts per thousand with samples showing both higher and lower values than that of the un-weathered diabase dike which shows a delta Ca-44/40 value of 0.65 parts per thousand. The variation in delta Ca-44/40 in the weathered samples is significantly higher than the external reproducibility of our measurements (< 0.1 parts per thousand) based on multiple measurements of Ca isotopic standards SRM 915a, SRM 915b and seawater (NASS-6). Mass balance calculations based on Sr/Ca and delta Ca-44/40 values rule out the contributions of secondary silicate as well as carbonate minerals in causing the variability of delta Ca-44/40 in the weathered samples. The positive correlations between delta Ca-44/40 and Mg/Al, Mg/Na in the weathered samples further negate the possible contribution of secondary carbonates in causing the variability in delta Ca-44/40, as Al and Na are unlikely to be present in carbonates. The samples with lower delta Ca-44/40 show higher CIA (Chemical Index of Alteration) values and Al/Ca than the UW diabase while samples having higher delta Ca-44/40 show lower CIA and Al/Ca than the UW diabase. The weathered sample having the lowest delta Ca-44/40 (close to the delta Ca-44/40 of plagioclase) exhibits the highest value of europium anomaly (Eu/Eu*). These observations are explained by the presence of variable relative proportions of residual clinopyroxene and plagioclase in the weathered diabase, due to selective weathering of these minerals. Since plagioclase and clinopyroxene could not be separated from the diabase, we measured the Ca isotopic compositions of a clinopyroxene (delta Ca-44/40= 1.06 parts per thousand) from the San Carlos mantle peridotite and plagioclase from the Chilka anorthosite complex (delta Ca-44/40= 0.40 parts per thousand) from the Eastern Ghats and used these isotopic values as representative of the compositions of these minerals in the diabase. Based on mixing models, using delta Ca-44/40, Al/Ca and Sr/Ca of the plagioclase and clinopyroxene end-members, we estimate that the delta Ca-44/40 of the UW diabase can be explained by 31 parts per thousand clinopyroxene and 69 parts per thousand plagioclase, which is consistent with the modal proportion of these minerals in an average unweathered diabase. Based on mixing calculations, the delta Ca-44/40, Sr/Ca and Al/Ca variability of the micro-drilled samples of the weathered diabase are explained by the presence of varying proportions of residual clinopyroxene (20-65 parts per thousand) and plagioclase (80-35 parts per thousand) in the weathered rock. This study demonstrates that selective weathering of major rock-forming minerals in nature can result in significant variation in delta Ca-44/40 in weathered rocks and that selective weathering of rock-forming minerals should be considered as an additional mechanism to explain the delta Ca-44/40 variability in rivers.

Assessing the carbon sequestration potential of basalt using X-ray micro-CT and rock mechanics

Mineral carbonation in basaltic rock provides a permanent storage solution for the mitigation of anthropogenic CO2 emissions in the atmosphere. 3D X-ray micro-CT (XCT) image analysis is applied to a core sample from the main basaltic reservoir of the CarbFix site in Iceland, which obtained a connected porosity of 2.05–8.76%, a reactive surface area of 0.10–0.33 mm−1 and a larger vertical permeability (2.07 × 10−10 m2) compared to horizontal permeability (5.10 × 10−11 m2). The calculations suggest a CO2 storage capacity of 0.33 Gigatonnes at the CarbFix pilot site. The XCT results were compared to those obtained from a hydromechanical test applied to the same sample, during which permeability, electrical resistivity and volumetric deformation were measured under realistic reservoir pressure conditions. It was found that permeability is highly stress sensitive, dropping by two orders of magnitude for a −0.02% volumetric deformation change, equivalent to a mean pore diameter reduction of 5 μm. This pore contraction was insufficient to explain such a permeability reduction according to the XCT analysis, unless combined with the effects of clay swelling and secondary mineral pore clogging. The findings provide important benchmark data for the future upscaling and optimisation of CO2 storage in basalt formations.