micro-CT Research Articles

Damage mechanisms of a metastable β-titanium alloy with bimodal microstructure revealed by void growth models using synchrotron X-ray microtomography

Damage mechanisms of a metastable β-titanium alloy with bimodal microstructure revealed by void growth models using synchrotron X-ray microtomography

NEW ASPECTS OF CORE MICROTOMOGRAPHY

Compared to many other technologies of laboratory studies of core samples, the modern «digital core» technology is a rather young scientific and industrial direction, but for decades it has attracted close attention of a wide range of scientists and specialists of the oil and gas industry (geologists, sedimentologists, lithologists, geophysicists, developers, geological modelers, hydrodynamicists, physicists). For many specialists of practical sphere new methodical techniques and methods of such researches remain little known. If earlier computer X-ray microtomographs in the Russian Federation were the prerogative of only academic structures or service organizations, nowadays many subsoil users have started to equip their own laboratory and research centers with the corresponding specialized equipment, understanding that without these data it is hardly possible to build high-quality geological, petrophysical, tectonic-physical, rheological, hydrodynamic and geological-field models of the studied sediments, as well as to prepare progragmatic models of the studied sediments. In this article the authors made an attempt to study and analyze the current state of development of «digital core» technology.Using extensive factual material the accumulated experience of special studies in the field of full-size core tomography is summarized, estimates of absolute permeability of low-permeability complex sediments are made, results of studying cores in frozen and unfrozen state are given, detailed analysis of fracturing at different stages of sample preparation and ongoing studies is carried out, and specific problems for which a solution using the technology is expected in the near future are formulated In this article the positive and negative sides of poroset and direct methods of modeling of filtration properties by digital core model are studied. Particular attention is paid to the need for large-scale studies to obtain statistically reliable data samples, which can be used to select the most qualitative methods of research and application of algorithms for processing of initial geological and geophysical information.

Metallic Artifacts’ Reduction in Microtomography Using the Bone- and Soft-Tissue Decomposition Method

Artifacts in computed tomography and X-ray microtomography are image distortions caused by various factors. Some can be reduced before or during the examination, while others are removed algorithmically after image acquisition. The latter group includes metallic artifacts caused by metal objects in the sample. This paper proposes a new method for eliminating metallic artifacts, applying a bone- and soft-tissue decomposition (BSTD) algorithm to microtomography raw data before the reconstruction process. We show that the decomposition algorithm can effectively remove metallic artifacts in microCT images, which increases the image contrast and allows for better visualization of regions near the metallic elements. For quantity analysis, we computed SSIM and PSNR factors, and we observed values increasing from 0.97 to 0.99 and from 40 dB to 43 dB, respectively.

Microstructure and development of the dermal ossicles of Antarctopelta oliveroi (Dinosauria, Ankylosauria): A complex morphogenetic system deciphered through three-dimensional X-ray microtomography.

Ankylosaurs were a group of heavily armored non-avian dinosaurs (Dinosauria, Ankylosauria), represented by a relatively abundant fossil record from the Cretaceous of North and South America. Their dermal skeleton was characterized by large osteoderms whose development and functional role have been largely investigated. However, interstitial small ossicles, forming between these osteoderms, have been far more overlooked and it remains unknown whether they were formed through the ossification of a preexisting fibrous matrix of connective tissue (i.e., metaplasia) or by a cell-induced differentiation of new fiber bundles followed by mineralization (i.e., neoplasia sensu (Zeitschrift für Wissenschaftliche Zoologie, 1858, 9, 147)). Here, we propose a hypothesis on the developmental origin of these small ossicles in the ankylosaurian Antarctopelta oliveroi using light microcopy, scanning electron microscopy and three-dimensional virtual histology through propagation phase-contrast synchrotron radiation micro-computed tomography (PPC-SRμCT). Ossicles are located in the dermis. They are composed of two layers: (1) a thin external layer, and (2) a thick basal plate, composed of collagen fiber bundles, which forms the main part of the ossicle. The external layer is made of a smooth, vitreous mineralized tissue that does not look like bone. The basal plate, however, is of osseous origin. In this basal plate, the collagen fiber bundles are organized in two orthogonal systems: one horizontal-observable in cross-sections-and one vertical-observable in the primary plane of sections sensu (Journal of Vertebrate Paleontology, 2004, 24, 874). The horizontal system is itself composed of successive layers of collagen fiber bundles arranged into an orthogonal plywood-like structure. The bundles of the vertical system radiate from the center of the ossicle at the level of the transition between the external layer and the basal plate and run towards the periphery of the basal plate. Their thickness increases from the center of the ossicle towards its periphery. Numerous bundles of the vertical system form thin threads that interweave and penetrate within the thick bundles of the horizontal system. Our new data suggest that the ossicles were at least partially formed by metaplasia, that is, through the ossification of a preexisting fibrous matrix of connective tissue. This process was probably supplemented by a cell-induced differentiation of new fiber bundles laid down prior to their incorporation into the fibrous system and its mineralization. This process looks more akin to neoplasia sensu (Zeitschrift für Wissenschaftliche Zoologie, 1858, 9, 147) than to metaplasia. Consequently, metaplastic and neoplastic processes may coexist in these ossicles with a possible differential expression during ontogeny.

Oxygen Consumption in Filamentous Pellets of Aspergillus niger: Microelectrode Measurements and Modeling.

Filamentous fungi cultivated as biopellets are well established in biotechnology industries. A distinctive feature of filamentous fungi is that hyphal growth and fungal morphology affect product titers and require tailored process conditions. Within the pellet, mass transfer, substrate consumption, and biomass formation are intricately linked to the local hyphal fraction and pellet size. This study combined oxygen concentration measurements with microelectrode profiling and three-dimensional X-ray microtomography measurements of the same fungal pellets for the first time. This allowed for the precise correlation of micromorphological information with local oxygen concentrations of two Aspergillus niger strains (hyperbranching and regular branching). The generated results showed that the identified oxygen-penetrated outer pellet regions exhibited a depth of 90-290 µm, strain-specific, with the active part percentage in the pellet ranging from 18% to 69%, without any difference between strains. Using a 1D continuum diffusion consumption model, the oxygen concentration in the pellets was computed depending on the local hyphal fraction. The best simulation results were achieved by individually estimating the oxygen-related biomass yield coefficient of the consumption term within each examined pellet, with an average estimated value of 1.95 (± 0.72) kg biomass per kg oxygen. The study lays the foundation for understanding oxygen supply in fungal pellets and optimizing processes and pellet morphologies accordingly.

Experimental and numerical characterization of E-glass/epoxy plain woven fabric composites containing void defects

The presence of voids in woven fabric composite (WFC) significantly affects the mechanical and thermomechanical properties. Void defects are introduced during the resin infiltration process due to various controlling parameters involved in the curing process, i.e., pressure, temperature, resin flow etc. In this study, the mechanical constants of 2D woven fabric composite were experimentally determined. A finite element (FE) based representative volume element (RVE) model has been validated against these experimental results. A multiscale-based FE model has been developed, and periodic boundary conditions are applied to the RVE model to evaluate the homogenized thermomechanical properties of WFC containing void defects. Present numerical model incorporates the geometrical microstructures of the post-cured woven composite and void contents obtained from X-ray microtomography. The influence of void defect and resin infiltration have been incorporated to evaluate the thermomechanical properties of plain WFC. A parametric study has been carried out with respect to the variation of void defects on thermoelastic properties of E-glass/epoxy plain WFC. The variation of void defects has been considered in micro and mesoscale models. Monte Carlo simulations further quantified the effects of void content on the thermomechanical constants of WFC. The presence of voids has been observed to have significant influences on the thermomechanical constants of yarn and woven fabric composites.

Acoustic emission and 4D X-ray micro-tomography for monitoring crack propagation in rocks

Acoustic emission (AE) and 4D X-ray computed tomography (4D XCT) were used simultaneously to study crack initiation and propagation in two different types of quartz-rich sandstones during the four-point bending experiments. Statistical analysis of the AE response indicated the failure mechanisms and their dynamics. The characteristic changes observed in the AE response defined the timing of the bending interruptions for XCT scanning to reveal the development of the crack. It was possible to quantitatively describe the developing cracks in their dimensions and volume and relate this information to the rate of decrease in the post-peak region of the material response. It could be concluded that the combination and concurrent use of AE and XCT techniques represents a highly effective and reliable instrument for observation, description, analysis of the crack propagation process, and rock disintegration in detail at a microscale level. With regard to the specific sandstones studied, Mšené sandstone is softer, respectively, less brittle, while Kocbeře sandstone is characterised by a more brittle behaviour accompanied by an AE signal with higher amplitudes compared to those of Mšené.

Two-phase regularized phase-field density gradient Navier–Stokes based flow model: Tuning for microfluidic and digital core applications

Here we present a regularized phase-field Navier–Stokes two-phase flow model with density gradient theory for interface treatment. The usage of regularization allows us for faster computations — for some particular simulation cases the time step could be increased x9 times. The computations are stable and spurious layers are suppressed with the help of nonlinear surface energy model. To verify the model we test rigorously against major classic problems: (1) droplet on a flat wall with given contact angle, (2) analytical solution for capillary rise, (3) hydrodynamical focusing within a micro-channel, (4) displacement in a pore doublet. As the application example, we simulate two-phase flow displacement within an X-ray microtomography scan of oil-bearing rock and demonstrate computation of relative permeabilities. We believe that developed model will be useful in numerous research applications: porous media design with desired physical properties, digital core technology applications to obtain flow properties of rocks and enhance hydrocarbon recovery, hydrological applications to study unsaturated flow in soils. Finally, we discuss potential improvements of the model as related to computational efficiency.

Radiopaque Polyurethanes Containing Barium Sulfate: A Survey on Thermal, Rheological, Physical, and Structural Properties.

Radiopaque polyurethanes are extensively used in biomedical fields owing to their favorable balance of properties. This research aims to investigate the influence of particle concentration on various properties, including rheological, radiopacity, structural, thermal, and mechanical attributes, with a thorough analysis. The findings are benchmarked against a commercial product (PL 8500 A) that contains 10% weight barium sulfate. Two more thermoplastic polyurethanes (TPU) were formulated with two different concentrations of barium sulfate (10 wt.% and 20 wt.%) and compared to the commercially available product. FTIR demonstrated similar absorption bands among all samples, indicating that the fabrication method did not impact the TPU matrix. DSC indicated a predominantly amorphous structure for PL 8500 A compared to the other samples, while the kinetic degradation was more influenced by the higher barium sulfate content. The rheological analysis showed a decrease in the complex viscosity and storage modulus with the radiopacifier and an increase in the radiopacity, as demonstrated by the X-radiography. X-ray microtomography showed a more spherical particle format with a heterogeneous particle structure for PL 8500 A compared to the other polyurethanes. These findings enhance the comprehension of the structure-property relationships inherent in these materials and facilitate the development of customized materials for targeted applications.

Impact of Formwork Materials on Concrete Surface Quality

Given the functional and aesthetic quality expected from concrete surfaces, this study investigated the influence of different formwork materials on their surface density, porosity, voids, and elementary chemical composition by relying on X-ray Microtomography (μCT), Scanning Electronic Microscopy (SEM), and Energy Dispersive X-ray Spectroscopy (EDS). The formwork materials assessed were galvanized steel, regular plywood (pink), marine plywood, polyvinyl chloride (PVC), and silicone. μCT showed that distinct formwork affected the surface density of the concrete. In this case, specimens cast within silicone and marine plywood had similar pore volumes although different pore sizes, whereas PVC led to the highest pore volume with small pore sizes. Galvanized steel and regular plywood resulted in similar porosity. SEM showed that the concrete surfaces produced with marine plywood formwork had the highest void content. EDS identified surface products resulting from the contact of concrete with the different formwork materials, suggesting the potential migration of chemical elements. This research significantly contributes to optimizing formwork material selection and enhancing concrete quality and durability. Moreover, it establishes a foundation for further investigations into how formwork materials affect concrete surfaces and the pathological manifestations potentially arising from the molding process.

The era of cybertaxonomy: X-ray microtomography reveals cryptic diversity and concealed cuticular sculpture in Aphanerostethus Voss, 1957 (Coleoptera, Curculionidae).

Weevils represent one of the most speciose and economically important animal clades, but remain poorly studied across much of the Oriental Region. Here, an integrative revision of the Oriental, flightless genus Aphanerostethus Voss, 1957 (Curculionidae: Molytinae) based on X-ray microtomography, multi-gene DNA barcoding (CO1, Cytb, 16S), and traditional morphological techniques (light microscopy, dissections) is presented. Twelve new species, namely, A.armatus Lewis & Kojima, sp. nov., A.bifidus Kojima & Lewis, sp. nov., A.darlingi Lewis, sp. nov., A.decoratus Lewis & Kojima, sp. nov., A.falcatus Kojima, Lewis & Fujisawa, sp. nov., A.incurvatus Kojima & Lewis, sp. nov., A.japonicus Lewis & Kojima, sp. nov., A.magnus Lewis & Kojima, sp. nov., A.morimotoi Kojima & Lewis, sp. nov., A.nudus Lewis & Kojima, sp. nov., A.spinosus Lewis & Kojima, sp. nov., and A.taiwanus Lewis, Fujisawa & Kojima, sp. nov. are described from Japan, Taiwan, Vietnam, and Malaysia. A neotype is designated for A.vannideki Voss, 1957. The hitherto monotypic genus Darumazo Morimoto & Miyakawa, 1985, syn. nov. is synonymized under Aphanerostethus based on new morphological data and Aphanerostethusdistinctus (Morimoto & Miyakawa, 1985), comb. nov. is transferred accordingly. X-ray microtomography is successfully used to explore for stable interspecific differences in cuticular, internal and micro morphology. Remarkable species-specific sexual dimorphism in the metatibial uncus is described in seven of the newly described Aphanerostethus species and the evolution of this character is discussed.

Novel application of SANS provides quantitative non-destructive identification of forming techniques in late Roman and early medieval pottery from Pannonia

Within archaeological studies of ancient pottery, understanding the techniques used to form vessels from unfired clay provides significant information on the history of technology and economic systems, as well as wider cultural practices and social interactions. We introduce here a new analytical methodology, using small-angle neutron scattering (SANS) to investigate pottery forming techniques through the preferential orientation of nanoscale objects within pottery fabrics. Significantly, SANS is non-destructive, suitable for both coarse and fine-textured pottery fabrics, provides quantitative data, enables fast-throughput of samples, and is not significantly affected by surface modifications occurring after the primary forming stage. The use of SANS is systematically investigated through over 400 measurements of experimental vessels, and also compared with X-ray microtomography and neutron tomography. The results show that SANS can be used to differentiate wheel-throwing, coil-building, percussion-building, and coil-wheeling techniques. The archaeological application of SANS is demonstrated through a case study of 50 late Roman and early medieval (fourth–sixth century AD) pottery sherds from Hungary, spanning the collapse of the Western Roman Empire and the arrival of Barbarian polities into the region. The findings show a transition in production from predominantly wheel-throwing to coil-wheeling, but also coil-building, percussion-building, percussion-wheeling, and drawing. Such changes appear to reflect the disintegration of large-scale centrally organised Roman economic systems, and the diversification of production, consistent with the more diversified technological and cultural backgrounds of the producers themselves.

Particle morphology and principal stress direction dependent strength anisotropy through torsional shear testing

The major principal stress direction angle (ασ) experienced by granular soils varies widely in engineering, causing different strengths. However, how particle morphology affects the strength anisotropy behavior under different ασ remains unclear. To address this gap, this study performed drained hollow cylinder torsional shear tests under different ασ on six granular materials with distinct morphologies. Results highlight the significant dependence of peak strengths of granular materials on both particle morphology and ασ. Increasing particle shape irregularity and surface roughness leads to a considerable enhancement in peak strength, while this peak strength significantly degrades with increasing ασ. Materials with more irregular shapes were found to have a more pronounced strength anisotropy. Furthermore, the initial fabric of particle packings, derived from three-dimensional X-ray microtomography, was used to interpret microscopic mechanisms behind the morphology-dependent strength anisotropy. Irregular-shaped materials display broader preferred particle orientations and higher initial fabric anisotropy compared to relatively regular-shaped materials. This higher morphology-induced fabric anisotropy contributes to strength anisotropy, and a correlation was established for describing this trend. Additionally, an anisotropic failure criterion incorporating fabric anisotropy was developed to characterize the strength envelope for granular materials with diverse shapes.

Superior anti-icing performance of a silicone-based slippery gel coating with a self-replenishing lubricant layer under airflow

Icing phenomena lead to energy consumption, mechanical failures, and potential human casualties. These issues often occur under dynamic airflow conditions. While superhydrophobic (SHPo) surfaces effectively delay ice formation under airflow, they cannot completely prevent it without external energy. This study proposes a long-chain entangled polydimethylsiloxane (LEP) gel coating infused with a lubricant, as an excellent anti-icing surface. The LEP gel has a self-regenerative, low-viscosity oil layer, and it shows remarkable droplet mobility, a very low contact angle hysteresis (CAH), and near-zero ice adhesion. X-ray microimaging shows that condensed droplets on the LEP gel move dynamically, while a bare silicone coating exhibits static behavior. This dynamic droplet behavior significantly delays droplet freezing and frost onset. The LEP gel’s anti-icing performance is assessed in a subsonic wind tunnel. Unlike control surfaces on which frost forms immediately, droplets condense on the gel and then slide off, reducing the frost-coverage rate. Notably, at a wind speed of 5.5 m/s, no frost is formed on the gel. The LEP gel’s superior anti-icing performance is attributed to synergistic effects of the lubricant layer and extremely low CAH. These results show that lubricant-infused slippery gel coatings could prevent icing in airflow environments.

New insights into the Devonian sea spiders of the Hunsrück Slate (Arthropoda: Pycnogonida).

The sea spiders (Pycnogonida Latreille, 1810) of the Hunsrück Slate (Lower Devonian, ~400 million years ago) are iconic in their abundance, exquisite pyritic preservation, and in their distinctive body plan compared to extant sea spiders (Pantopoda Gerstäcker, 1863). Consequently, the Hunsrück sea spiders are important in understanding the deep evolutionary history of Pycnogonida, yet they remain poorly characterised, impacting upon attempts to establish a time-calibrated phylogeny of sea spiders. Here, we investigated previously described and new material representing four of the five Hunsrück pycnogonids: Flagellopantopus blocki Poschmann & Dunlop, 2006; Palaeoisopus problematicus Broili, 1928; Palaeopantopus maucheri Broili, 1929; and Pentapantopus vogteli Kühl, Poschmann & Rust, 2013; as well as a few unidentified specimens. Using X-ray microtomography and Reflectance Transformation Imaging, we describe new fossils, provide evidence for newly revealed anatomical features, and interpret these data in comparison to extant species. We also reinterpret the previously published illustration of the (probably lost) holotype of Palaeothea devonica Bergström, Stürmer & Winter, 1980. We provide the first detailed description of the cephalic appendages of Palaeoisopus problematicus and revise the interpretation of the organisation of its ocular tubercle. Furthermore, we provide new insights into the structure of the legs and the proboscis of Palaeopantopus maucheri, the first description of the body of Flagellopantopus blocki and describe a new specimen of Pentapantopus vogteli, demonstrating that it had eight legs, in contrast to previous interpretations. We argue that, contrary to previous suggestions, Palaeothea devonica probably had a different body plan from extant pantopods. We discuss the ecological traits of the Hunsrück pycnogonids based on their morphological adaptations, and conclude that there is no compelling evidence of Pantopoda in the Devonian. Through comparative interpretation of the legs as well as general morphology, we can divide the Hunsrück pycnogonids into two morphological groups, while Pantopoda constitutes a third morphological group.

Determination of the geometric parameters of the defects based on the tomographically obtained data and their influence on the fatigue behavior of the S960 with laser cladded protective layers

This article deals with identifying defects of layered high strength steel materials with the help of tomography measurement. Test samples were made of S960 High Strength Steel to which layers of either aluminium bronze, hardchrome, cobalt alloy or stainless steel were applied by a laser cladding technology. The experimental campaign included a study of morphometric parameters of internal defects in and near the bi-material interface region using X-ray micro-tomography and their potential influence on the fatigue behavior during a three-point bending test.

Characteristics and distribution of microstructures in high pressure die cast alloys with X-ray microtomography: A review

Characteristics and distribution of microstructures in high pressure die cast alloys with X-ray microtomography: A review

Evolution and functional implications of stinger shape in ants.

Trait diversification is often driven by underlying performance tradeoffs in the context of different selective pressures. Evolutionary changes in task specialization may influence how species respond to tradeoffs and alter diversification. We conducted this study to investigate the functional morphology, evolutionary history, and tempo and mode of evolution of the Hymenoptera stinger using Ectatomminae ants as a model clade. We hypothesized that a performance tradeoff surface underlies the diversity of stinger morphology and that shifts between predatory and omnivorous diets mediate the diversification dynamics of the trait. Shape variation was characterized by X-ray microtomography, and the correlation between shape and average values of von Mises stress, as a measure of yield failure criteria under loading conditions typical of puncture scenarios, was determined using finite element analysis. We observed that stinger elongation underlies most of the shape variation but found no evidence of biomechanical tradeoffs in the performance characteristics measured. Additionally, omnivores have increased phenotypic shifts and accelerated evolution in performance metrics, suggesting the evolution of dietary flexibility releases selection pressure on a specific function, resulting in a greater phenotypic evolutionary rate. These results increase our understanding of the biomechanical basis of stinger shape, indicate that shape diversity is not the outcome of simple biomechanical optimization, and reveal connections between diet and trait diversification.

Microscopic insights into thermal cycling effects in granular materials via X-ray microtomography

Microscopic insights into thermal cycling effects in granular materials via X-ray microtomography

Microstructure and compressive behaviour of PLA/PHA-wood lattice structures processed using additive manufacturing

This study investigates the microstructure and compressive behaviour of PLA/PHA-wood lattice structures manufactured using fused filament fabrication (FFF). The primary objective is to evaluate the effects of defects, such as porosity and surface roughness, on the mechanical properties of these lattice structures. X-ray micro-tomography (XRT) and finite element analysis are employed to compare CAD models with real lattice structures, offering insights into defect-induced performance deviations. The novel approach integrates experimental and numerical methods to better understand damage accumulation in porous structures. The methodology includes uniaxial compression testing and image processing for microstructural characterization. Results reveal significant differences in relative density and stress concentration due to manufacturing defects. In particular, 3D printed lattice structures display typical cellular material behaviour with a primary bending deformation mechanism. X-ray tomography reveals that process-induced porosity generate stress heterogeneity, which is not captured from CAD-based model resulting in an overestimation of the stiffness. The study concludes that accounting for these defects can be quantified by shifting the target relative density to compensate lack of performance in 3D-printed lattice materials.