X-ray Micro-computed Tomography Research Articles

X-ray Computed Microtomography Evaluation of Electrochemically Accelerated Stainless Steel Crevice Corrosion

Abstract This work reports the electrochemical and X-ray tomography characterization of crevice corrosion for an additively manufactured stainless steel. The cell design includes a three electrode configuration with an integrated crevice former for full electrochemical control. The crevice former design utilized a spring to induce force upon the crevice former and tape to defined the crevice. The cell was evaluated with a series of potentiostatic holds from 0.05 to 0.95 VSCE to observe crevice corrosion initiation and propagation across a range of current densities. In this proof of concept demonstration, X-ray computed microtomography (XCMT) reconstructions were used to observed electrochemical potential dependent crevice corrosion propagation that was compared with coulometry and postmortem profilometry. Volume loss calculations based on XCMT reconstructions displayed good correlation with electrochemical measurements. We demonstrate this approach as a promising non-destructive tool for crevice corrosion characterization, limited primarily by the inherent limitations of X-ray tomography systems.

Innovative alginate-clay shell and magnetite-gelatin core composite for multifaceted contaminant removal: Cadmium, thiabendazole and bacterial adsorption from aqueous solutions.

In this study, a novel magnetic composite adsorbent with an alginate-chamotte clay outer layer and a gelatin-magnetite core was synthesised for effective contaminant removal from aqueous solutions. The alginate component ensures biocompatibility, chamotte clay enhances adsorption, gelatin provides mechanical strength, and magnetite enables easy recovery of the adsorbent. The composite material was characterised using Fourier-transform infrared, X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy-energy-dispersive X-ray analysis, micro-computed tomography, Brunauer-Emmett-Teller analysis and dynamic mechanical analysis techniques. Response surface methodology was employed to optimise cadmium and thiabendazole adsorption. Optimal conditions for cadmium removal were achieved at pH7 using 500mg of adsorbent, with a 30-min contact time and a 5mL sample volume. Additionally, thiabendazole adsorption was optimal at pH3, with a 65-min contact time. Thermodynamic and kinetic experiments revealed that both adsorption processes were spontaneous and endothermic and followed a pseudo-second-order model. Cadmium adsorption aligned with Langmuir isotherm , while thiabendazole adsorption followed Freundlich isotherm . The adsorbent also showed high antibacterial efficiency, effectively removing both Gram-positive S. aureus and Gram-negative E. coli, with adsorption capacities of 43.86mgg-1 for cadmium, 5.01mgg-1 for thiabendazole, 2.5×1010CFUg-1 for E. coli and 6.7×1010CFUg-1 for S. aureus. These results highlight the multifunctional potential of the adsorbent for wastewater treatment.

Experimental Investigation of Burst Failure Mechanism Under Polyaxial Loading Conditions

Abstract Effective monitoring and early warning methods are crucial for enhancing safety and sustainability in deep resource extraction, which are particularly important for mitigating rock/coal burst failures. This study introduces a newly modified thick-walled hollow cylinder (TWHC) testing system for rock and coal burst at the laboratory scale. Fracture initiation and propagation, leading to bursting on the wall of a cylindrical opening in granite, bluestone and coal are characterised by real-time acoustic emission (AE) responses. In this study, a borescope was used synchronously to observe the dynamic failure processes of rock/coal bursts and to verify AE results. The internal fracture morphologies of granite, bluestone and coal specimens were acquired using X-ray micro-Computed Tomography (μCT). We analysed the intrinsic mechanism of strain energy evolution of bursting and found that the average energy consumed by the induced cracking and released kinetic energy during bursting is approximately ~ 8, 25 and 18% of the total absorbed strain energy of granite, bluestone and coal, respectively. We found the average mass of the ejected rock/coal fragments to be ~ 0.3–0.5 g, whilst the rock/coal ejection velocity ranged from 10.5 to 19.8 m/s for the hollow coal, bluestone and granite. The results also indicate that granite and bluestone have the highest potential for violent bursting failure.

Water phase distribution and its dependence on internal structure in soaking maize kernels: a study using low-field nuclear magnetic resonance and X-ray micro-computed tomography

IntroductionThe formation of yield and quality in maize involves the accumulation of substances such as starch, proteins, and fats, which interact with water within the kernel. Although temporal dynamics of grain moisture and its functional and environmental determinants have been broadly demonstrated, we still do not have a comprehensive understanding of the distribution of water phase within a kernel.MethodsWe investigated the relationship between tissue structural traits, including embryo volume (EMBV), endosperm volume (ENDV), vitreous endosperm volume (VEV), floury endosperm volume (FEV), and water content in different phases, such as bound water, semi-bound water, and free water, in maize kernels under different cultivars, nitrogen application rates, and soaking durations by combining low-field nuclear magnetic resonance (LF-NMR) and X-ray microcomputed tomography (μ-CT) for kernels.ResultsThe results demonstrate that bound water is the major phase (57-82%) in maize kernels, and this proportion decreases with prolonged soaking duration. The bound water content and semi-bound water content positively correlate to ENDV, VEV, and EMBV, whereas free water content correlates to ENDV, EMBV, and VEV in descending order of correlation coefficient. This indicates that water might penetrate the embryo through the pedicel and vitreous endosperm through the pericarp during soaking.DiscussionFinally, we suggested that the proportion of semi-bound water could be a robust indicator to predict moisture content in maize kernels. The study provides a preliminary understanding of the structural basis of water distribution in maize kernels, thereby opening up the potential for designing efficient production systems and breeding cultivars well-suited for mechanical harvesting.

Micro-computed tomography and laser micro-ablation on altered pyrite in lapis lazuli to enhance provenance investigation: a new methodology and its application to archaeological cases

This work presents an upgrade to the methodology adopted to investigate the provenance of the raw lapis lazuli material used in antiquity for carving precious artefacts. Samples from archaeological excavation contexts frequently display superficial degradation processes affecting the crystals of the mineral phases useful for provenance attribution (especially pyrite). To address this issue, an innovative workflow has been developed, centred on the application of X-ray micro-computed tomography (μ-CT) and micro-ablation treatments with a pulsed laser source prior to investigation with ion beam analysis (IBA). High-resolution μ-CT is employed to evaluate the alteration state of pyrite crystals within the entire volume of the lapis lazuli rock, and, if required, to identify the most suitable crystals on the surface for subsequent laser treatment. The micro-ablation procedure aims to create a small breach in the superficial altered layer (the irradiated areas are approximately 65 × 65 μm2), thereby exposing the preserved crystal beneath and allowing for the analysis of its trace element contents with IBA. The methodology of the workflow is presented, together with its first application to archaeological lapis lazuli material: three precious beads from the ancient Royal Cemetery of Ur (Mesopotamia, 3rd millennium BCE). The results are complemented by the application of a provenance protocol already validated that proved, for the first time using a micro-invasive analytical approach, a match between the Afghan quarry district and the raw material used to carve these beads.

Macro-Micro Mechanics of Granular Soils Under Shear Considering Coupled Effects of Particle Size Distribution and Particle Morphology.

This paper investigates the effects of particle morphology (PM) and particle size distribution (PSD) on the micro-macro mechanical behaviours of granular soils through a novel X-ray micro-computed tomography (μCT)-based discrete element method (DEM) technique. This technique contains the grain-scale property extraction by the X-ray μCT, DEM parameter calibration by the one-to-one mapping technique, and the massive derivative DEM simulations. In total, 25 DEM samples were generated with a consideration of six PSDs and four PMs. The effects of PSD and PM on the micro-macro mechanical behaviours were carefully investigated, and the coupled effects were highlighted. It is found that (a) PM plays a significant role in the micro-macro mechanical responses of granular soils under triaxial shear; (b) the PSD uniformity can enhance the particle morphology effect in dictating the peak deviatoric stress, maximum volumetric strain, contact-based coordination number, fabric evolution, and shear band formation, while showing limited influences in the maximum dilation angle and particle-based coordination number; (c) with the same PSD uniformity and PM degree, the mean particle volume shows minimal effects on the macro-micro mechanical behaviours of granular soils as well as the particle morphology effects.

Synchrotron X-ray micro-computed tomography enhances our knowledge of the skull anatomy of a Late Triassic ecteniniid cynodont with hypercanines.

Hypercanines, or hypertrophied canines, are observed in a wide range of both extinct and extant synapsids. In non-mammaliaform cynodonts, the Permo-Triassic forerunners of mammals, long canines are not uncommon, appearing in several unrelated taxa within the clade. Among them is Trucidocynodon riograndensis, a carnivorous ecteniniid cynodont from the Late Triassic of Brazil, which exhibits a specialized dentition, including spear-shaped incisors, very long and narrow canines, and sectorial postcanines with distally oriented cusps, all of which have finely serrated margins. Recent synchrotron X-ray micro-computed tomography of a large specimen (CAPPA/UFSM 0029; Várzea do Agudo site, Brazil) provides new insights into its lower jaw and dentition, as well as offers the first digital endocast of an ecteniniid. Our study reveals the presence of (i) putatively opened-root canines in the adult stage and the possible presence of unresorbed remnant of an old canine, which may indicate that the specimen stopped replacing its canines; (ii) lower canines that are longer than the upper canines and, in occlusion, were kept inside deep paracanine fossae that perforated the dorsal surface of the rostrum; (iii) a diastema between the incisors and lower canine, which is absent in the holotype; (iv) advanced brain structures, such as the absence of a pineal body, presence of cerebral hemispheres divided by the interhemispheric sulcus and expanded laterally, and a higher encephalization quotient than non-mammaliaform prozostrodonts, reflecting the homoplastic evolution of relative brain sizes observed in Triassic cynodont lineages. Finally, the abundance of carnivorous and omnivorous species at the Várzea do Agudo site, where the specimen was found-including the archosauriforms Dynamosuchus collisensis and Stenoscelida aurantiacus-suggests a diverse predator guild that warrants further investigation from a paleoecological perspective.

Quantitative Structural and Compositional Elucidation of Real-World Pharmaceutical Tablet Using Large Field-of-View, Correlative Microscopy-Tomography Techniques and AI-Enabled Image Analysis.

The purpose of this study is to present a correlative microscopy-tomography approach in conjunction with machine learning-based image segmentation techniques, with the goal of enabling quantitative structural and compositional elucidation of real-world pharmaceutical tablets. Specifically, the approach involves three sequential steps: 1) user-oriented tablet constituent identification and characterization using correlative mosaic field-of-view SEM and energy dispersive X-ray spectroscopy techniques, 2) phase contrast synchrotron X-ray micro-computed tomography (SyncCT) characterization of a large, representative volume of the tablet, and 3) constituent segmentation and quantification of the imaging data through user-guided, iterative supervised machine learning and deep learning. This approach was implemented on a real-world tablet containing 15% API and multiple common excipients. A representative volumetric tablet image was obtained using SyncCT at a 0.36-µm resolution, from which constituent particles and pores were fully segmented and quantified. As validation, the derived tablet formulation composition and porosity agreed with the experimental values, despite the micrometer-scale particle and pore sizes. The approach also revealed the formation of ordered mixture inside the tablet. Notably, the image-derived size distributions of both the agglomerated microcrystalline cellulose and its primary particulate units matched the laser diffraction-based measurements of the as-is material. Key pore attributes including the pore size distribution, spatial anisotropy, and pore interconnectivity were also qualified. Overall, this study demonstrated that the correlative microscopy-tomography approach, by leveraging phase contrast SyncCT and AI-based image analysis, can deliver new, practically-useful structural and compositional information and facilitate more efficient formulation and process development of tablets.

Advancing microplastic detection in zebrafish with micro computed tomography: A novel approach to revealing microplastic distribution in organisms.

The analysis of microplastics with current spectroscopic and pyrolytic methods is reaching its limits, especially with regard to detailed spatial distribution in biological tissues. This limitation hampers a comprehensive understanding of the effects of microplastics on organisms. Therefore, there is a pressing need to expand the analytical approaches to study microplastics in biota. In this context, the aim of this study was to test the applicability of non-destructive 3D imaging using X-ray micro-computed tomography (microCT) for the detection of microplastics in fish. Zebrafish (Danio rerio) were gavaged with polyethylene spherical microplastics (30-110 μm) and the distribution of microplastics in the gut was investigated using microCT. The results showed that the particle size distribution determined by microCT closely matched the data from conventional laser diffraction analysis. In addition, microCT was able to detect microplastics in spiked fish tissue and provide precise localization data by tracing particles of known type and shape. MicroCT offers a novel approach for tracking microplastics in organisms and enables accurate sizing without compromising the integrity of the tissue under investigation. It therefore represents a valuable addition to spectroscopic methods, which are widely used for the detection of microplastics based on their chemical composition but do not provide data on their spatial distribution.

The use of ethanol as contrast enhancer in synchrotron X-ray phase-contrast imaging leads to heterogeneous myocardial tissue shrinkage: a case report.

One of the main limitations of conventional absorption-based X-ray micro-computed tomography imaging of biological samples is the low inherent X-ray contrast of soft tissue. To overcome this limitation, the use of ethanol as contrast agent has been proposed to enhance image contrast of soft tissues through dehydration. Some authors have shown that ethanol shrinks and hardens the tissue too much, also causing small tissue ruptures due to fast dehydration. However, the local tissue deformation occurring as a consequence of tissue dehydration and whether tissue shrinkage can modify myocardial architecture has not been quantified yet. The aim of this paper is to quantify the local myocardial tissue deformation due to ethanol dehydration based on 3D non-rigid registration and perform a detailed characterization of its myocardial tissue organization, before and after ethanol dehydration. A rat adult heart was imaged with synchrotron-radiation-based X-ray phase contrast imaging (X-PCI) three times: before, 9 h after and 342 h after ethanol immersion. The total volume shrinkage as well as changes in the left ventricular myocardial thickness were computed. Then, to determine local deformation of the heart caused by ethanol dehydration, the related 3D tomographic datasets were registered by means of a non-rigid registration algorithm. Finally, changes on the orientation and organization of myocytes were assessed. Our results show that the use of ethanol in synchrotron X-PCI can improve image contrast, but the tissue shrinkage is not homogeneous thus changing the local myocardial organization.

A systematic study of the effect of measurement parameters on determination of osteocyte lacunar properties using laboratory X-ray micro-computed tomography.

Accurate 3D characterization of osteocyte lacunae is important when investigating the role of osteocytes under various physiological and pathological conditions but remains a challenge. With the continued development of laboratory X-ray micro-computed tomography, an increasing number of studies employ these techniques beyond traditional bone morphometry to quantify osteocyte lacunae. However, there is a lack of knowledge on the effect of measurement parameters on the image quality and resolution and in turn the osteocyte lacunae quantification. Herein, we have examined the interplay between scan parameters and the resultant lacunar quantification in terms of lacunar size, shape, and density by comparison with a synchrotron benchmark dataset. We summarize our conclusions in a guide for use of μ-CT for osteocyte lacunar quantification: (1) Identification of the measurement requirements to address the research questions. (2) Collection and preparation of suitable sample(s) that fulfills these requirements. (3) Experimental considerations including determination of the required voxel size, in turn dictating the maximum FOV and by extension the maximum size of the sample(s). The experimental parameters chosen should ensure optimal image contrast, sufficient signal to noise, angular sampling etc. Usually, it is advisable to measure as well as possible within the limits of time, budget, data storage and analysis capabilities. (4) Data analysis and reporting of the results, including visual examination of the data at multiple steps in the analysis, to ensure correct feature identification and suitable reporting approaches. (5) Cross study comparisons, which may be unsuitable if the experimental conditions and analysis strategies are not comparable.

Laser scribed proton exchange membranes for enhanced fuel cell performance and stability

High-temperature proton exchange membrane fuel cells (HT-PEMFCs) offer solutions to challenges intrinsic to low-temperature PEMFCs, such as complex water management, fuel inflexibility, and thermal integration. However, they are hindered by phosphoric acid (PA) leaching and catalyst migration, which destabilize the critical three-phase interface within the membrane electrode assembly (MEA). This study presents an innovative approach to enhance HT-PEMFC performance through membrane modification using picosecond laser scribing, which optimises the three-phase interface by forming a graphene-like structure that mitigates PA leaching. Our results demonstrate that laser-induced modification of PA-doped membranes, particularly on the cathode side, significantly enhances the performance and durability of HT-PEMFCs, achieving a peak power density of 817.2 mW cm⁻² after accelerated stress testing, representing a notable 58.2% increase compared to untreated membranes. Furthermore, a comprehensive three-dimensional multi-physics model, based on X-ray micro-computed tomography data, was employed to visualise and quantify the impact of this laser treatment on the dynamic electrochemical processes within the MEA. Hence, this work provides both a scalable methodology to stabilise an important future membrane technology, and a clear mechanistic understanding of how this targeted laser modification acts to optimise the three-phase interface of HT-PEMFCs, which can have impact across a wide array of applications.

Microstructural characterization of a wheat-based food material using image analysis and pore network modeling during baking.

Microstructural properties of wheat-based food materials change during baking. These alterations affect the final product's mechanical properties, physical attributes, and consumer satisfaction. Image processing and pore network modeling were used to analyze the variations in a cookie's microstructural properties during baking. Cookies were baked in an oven set at 184±2°C for 10-60min and then freeze-dried. Over 1500 two-dimensional images were collected for each sample using X-ray micro-computed tomography. Image processing and pore network modeling were utilized to obtain porosity, pore size distribution, tortuosity, pore coordination number, permeability, and other properties. A gas pycnometer was used to validate the obtained porosity values and calculate the solid density. Three stages of expansion, shrinkage, and subsequent expansion were observed during baking. The total porosity ranged between 0.145 and 0.373. The largest pores were observed in the 20-min baked sample, which had a moisture content of 8.53g/100g solids. Cookies baked longer had more interconnected pores than the 10-min sample, enabling them to conduct fluid at a higher rate. The absolute permeability values were between 1.75 × 10-11 m2 and 4.68 × 10-11 m2. The results suggested that porosity and pore coordination number had a similar trend as cookie permeability. Both heat and mass transfer during baking are expected to influence the development of the porous structure. PRACTICAL APPLICATION: Understanding the microstructural properties of wheat-based food materials is expected to help the baking industry control processing conditions, final product quality, and visual texture by adjusting the baking parameters.

Comparison of Low-Brilliance X-Ray Phase-Contrast Tomography and Contrast-Enhanced Attenuation-Contrast Micro-Computed Tomography of Rat Kidneys.

Structural analysis of soft biological tissues is conventionally done with destructive 2D histology. 3D information can be accessed with non-invasive imaging methods, such as X-ray micro-computed tomography (micro-CT). While attenuation-based X-ray imaging alone does not provide reasonable contrast with soft-tissue samples, the combination with contrast-enhancing staining has proven effective. The staining process, however, comes with several disadvantages, such as tissue alterations and laboriousness. A novel X-ray imaging method known as phase-contrast imaging has emerged as an interesting alternative to contrast-enhanced micro-CT. Our objective is to show the feasibility of laboratory-based phase-contrast imaging in (murine) kidney research. X-ray phase-contrast images of male rat kidneys were acquired with a Talbot-Lau interferometer. Moreover, attenuation-based X-ray images of the same unstained kidneys were acquired with a regular micro-CT device. Afterwards, the kidneys were stained with phosphotungstic acid for several months. Attenuation-based micro-CT images were re-acquired after the staining. Contrast-to-noise ratio was evaluated for all three cases. For unstained kidneys, the phase-contrast images show significantly improved contrast in comparison with attenuation images. Several key features, including the cortex, inner and outer medulla, papilla, as well as the main blood vessels can be identified. While the contrast in attenuation images improves significantly after staining, the benefit is deteriorated by sample areas that the contrast agent did not reach properly; even after 206 days. Our results indicate that X-ray phase-contrast imaging is a viable option for kidney imaging in a laboratory setting providing comparable or better results than contrast-enhanced micro-CT. With imaging setups optimized for image resolution and faster imaging times, the advantages of phase-contrast imaging will be even greater.

Biting behavior against Varroa mites in honey bees is associated with changes in mandibles, with tracking by a new mobile application for mite damage identification

Certain populations of feral or wild European Honey Bees (EHB), Apis mellifera, have developed a tolerance of or persistence against the parasitic mite Varroa destructor in the USA. Although the grooming or mite-biting behavior is a trait bees use to defend against parasitic Varroa mites, little information is available concerning the grooming or mite-biting behavior of feral EHBs. Accordingly, we observed damaged mites of feral bees in Ohio (Apis mellifera ligustica) and commercial bees in four field seasons, 2020 to 2023, as well as feral bees in Kentucky (A. mellifera mellifera) in 2023, for a total of 7494 mites. When the mite-biting behavior was compared among these three populations, feral bees of Ohio (A. m. ligustica) and Kentucky (A. m. mellifera) displayed a significantly higher percentage (22% and 27% more) than the commercial bees. To investigate the mechanism of the mite-biting behavior, we examined bee mandibles. Mandibles are the primary mouthparts and tools used to remove or amputate the Varroa mites. Gentle Africanized honey bees (gAHB, A. mellifera scutellata-hybrid) in Puerto Rican exhibit mite resistance through microevolution on the island. Asian honey bees (A. cerana) are the original natural host of V. destructor. However, little has been reported on the morphometric analysis of mandibles between the two species A. cerana and A. mellifera and between the subspecies A. m. scutellata-hybrid and A. m. ligustica. Utilizing X-ray micro-computed tomography (microCT), we then examined the three-dimensional morphology of mandibles in (1) A. cerana, (2) gAHB A. m. scutellata-hybrid, (3) Ohio feral A. m. ligustica, and (4) package or commercial colonies A. m. ligustica. Our findings revealed distinctive three-dimensional shapes of mandibles, indicating substantial variations among these populations. These variations suggest that mandible morphology has an integral role in the bee’s defensive mechanisms against parasitic mites. We also developed the first smartphone application to quantify the mite damage by applying artificial intelligence to image analysis. This research contributes valuable insights into the prospective selection and breeding of honey bees with enhanced mite resistance, thus promoting the sustainability of apiculture.

Multi-resolution X-ray micro-computed tomography images of carbonate rocks from brazilian pre-salt

The recent surge in artificial intelligence (AI) advancements has been driven by the availability of open datasets for model development and evaluation. However, in the field of earth sciences, particularly in digital rock physics applications, open data remains scarce. To bridge this gap, we introduce a dataset comprising 16 rock samples from the Brazilian pre-salt region, available in both low resolution (48 μm - 64 μm) and high resolution (6 μm - 8 μm). The dataset also includes their respective segmented images into pore and matrix. Furthermore, porosity and permeability values obtained from laboratory measurements are provided for all samples. This dataset serves as a valuable resource for developing and benchmarking AI-based superresolution/segmentation models. Additionally, it can be utilized to develop models for predicting porosity and permeability directly from μ-CT images.

"3D channel maze" to control drug release from multiple unit tablets.

Diffusion is defined as general mechanism for drug release from advanced delivery systems, yet dynamic structure of dosage form intrinsically plays an unknown role. The synchrotron radiation X-ray micro-computed tomography (SR-μCT) three-dimensional (3D) imaging and in-depth analysis of 3D structures were applied to readily differentiate materials and accurately capture internal structure changes of multiple unit pellet system (MUPS) and the constituent pellets, visualizing internal 3D structure of a MUPS of theophylline tablets for their 3 levels hierarchy structures: pellets with rapid drug release characteristics, a protective cushion layer and a matrix layer. Drug release pathways were extracted from SR-μCT images and a 3D maze network was constructed using pore network analysis to quantify the internal structural evolution during drug release. In the initial stage of dissolution about 1h, theophylline release from the MUPS is dominated by diffusion from the matrix layer, whilst the second phase of 23h constant release kinetics is dominated by a 3D channel maze architecture with outlets/channels connecting pellets in the remains of the MUPS, which forms the 3D channel maze as pore networks. The random walking of the dissolved theophylline molecules retarded by the tortuous 3D channel maze which led to the observed controlled release profile as a whole. Based on SR-μCT investigations and 3D structure analysis, a new approach to control drug release via a 3D channel maze structure was discovered.

Development and microstructural characterization of ultra-lightweight aggregate concrete incorporating different sizes of polypropylene fibers

In this study, ultra-lightweight concrete with an oven-dry density of 800 kg/m3 was produced using expanded glass as the lightweight aggregate. Polypropylene fibers of different sizes were incorporated into the specimens to examine their effects on the material properties, such as drying shrinkage and flexural strength. The target dry density was achieved by applying the packing density concept to optimize the mix grading and calculate the content of each concrete component. Specimens with different ratios of short and long fibers were produced. Their fresh state, mechanical performance, and physical properties were extensively analyzed using various methods, including X-ray micro-computed tomography to examine the microstructure. The experimental results indicated a significant reduction in drying shrinkage for the fiber incorporated specimens, dependent on the fiber length and content. The compressive strength of the specimens exceeded 12 MPa. Moreover, the inclusion of polypropylene fibers notably enhanced the flexural strength by approximately 60%, while the lower density contributed to substantially reduced thermal conductivity by up to 26%, which is beneficial for thermal insulation. These results confirm that polypropylene fibers can be used to produce ultra-lightweight concrete with self-leveling properties, without compromising mechanical and physical performance.

Implications of compressive loading of the stomach wall: Interplay between mechanical deformation and microstructure.

During gastric surgery, the stomach wall is compressed with clamps and sutures or staple lines. These short- and long-term deformations can severely compromise the integrity of the tissue and make it difficult for the stomach wall to respond and remodel to the new loading conditions. Consequently, serious intra- and postoperative complications such as the formation of leaks during bariatric surgeries, can be associated with these immense tissue deformations. Hence, the study aimed to investigate the effects of compressive loading of the stomach wall in the radial direction. This was done by macroscopic mechanical loading of the stomach wall in each region of the stomach and evaluating the microstructural changes inflicted in the tissue. For this purpose, several imaging techniques were used, i.e., a histological analysis, second-harmonic generation microscopy, and X-ray micro-computed tomography. The combination of these three methods allowed us to investigate the gradual compression of the different stomach layers as well as the local reorientation and deformation of the main microstructural components, e.g., collagen fibers and muscle bundles. Importantly, this study found that the collagen bundles in the stomach wall straighten and reorient toward the circumferential-longitudinal plane and partially fan out with increased radial compressive deformation. The 3D scans of the stomach wall indicated a deterioration of the blood vessels and buckling of the mucosal glands due to compression. Statement of significance Unfortunately, little is known about the load transfer in the stomach wall during gastric surgery and the associated deformations on the macro- and microscale. The present study investigates the structural changes of the stomach wall, its layers and the inherent biological building blocks using histology, multi-photon microscopy, and micro-computed tomography. For the first time, the layer-specific response to stepwise radial compression of the stomach wall was studied, the related collagen fiber parameters were estimated, and a 3D sample structure was visualized. This clinically-oriented study links the structural changes within the wall to the postoperative remodel- ing process and the irreversibly altered gastric motility, thereby underscoring its relevance to the field of biomedical engineering, e.g., the development and improvement of surgical instruments.

Calcification and ecological depth preferences of the planktonic foraminifer Trilobatus trilobus in the central Atlantic.

Understanding the controls behind the calcification and distribution of planktonic foraminifera in the modern ocean is important when these organisms are used for palaeoceanographic reconstructions. This study combines previously reported shell mass data with new shell geochemistry, light microscopy and X-ray micro-computed tomography analyses to dissect various parameters of Trilobatus trilobus shells from surface sediments, investigating the factors influencing their biometry. The goal is to understand which aspects of the marine environment are critical for the calcification and vertical distribution of this species. Trilobatus trilobus is found to produce larger, thinner and overall lighter shells in equatorial regions than in subtropical gyre regions, where the shells are up to 4% smaller, more than 60% thicker and approximately 45% heavier. The skeletal mass percentage together with other calcification metrics (shell weight and thickness) are found to depend primarily on ambient seawater salinity rather than carbonate chemistry. In line with their degree of calcification, on the basis of geochemically reconstructed apparent calcification depths, this group of organisms is found shallower in the water column at the Equator and the subtropical gyres, while its habitat deepens in between these regions at the extra-equatorial sites. Furthermore, it is demonstrated that in the (central) Atlantic, it occupies a density layer slightly below the salinity maximum isopycnal at various depths, presumably by adjusting its shell properties.