Search Results (397)

Friction stir-welding (FSW) is widely recognized as a modern solid-state technology used to join dissimilar materials by solid-state mechanical mixing. Such mechanical mixing can be exploited to fabricate in situ composite structures through solid-state deformation mechanisms. The present investigation highlights the microstructural evolution and mechanical properties of an in situ composite structure fabricated by FSW of aluminum (Al) to titanium (Ti) incorporating a thin Nickel (Ni) interlayer. A 0.1 mm thick Ni foil was placed across the full butt interface between 4 mm thick Al and Ti plates before friction stir-welding. Properties of the composite were investigated in detail, and the results revealed that fragmented Ti and Ni particles of different sizes were consolidated in the weld nugget. Al, on the other hand, exhibited substantial microstructural refinement and developed an equiaxed microstructure with random grain orientation, mixed grain boundaries and low micro-strain accumulation in the weld nugget. At the processing temperature, Al reacted with both Ti and Ni to form multiple intermetallic compounds. Tensile testing indicated that the tensile properties of the weld were close to those of the base aluminum. This retention of mechanical properties in spite of recrystallization is attributed to the following mechanisms: (1) Ti and Ni undergo severe deformation, forming fine particles with varying sizes and shapes; (2) at particle interfaces, diffusion and chemical reactions produce interlayers and intermetallic compounds; (3) these particles are consolidated within dynamically recrystallized Al, imparting composite characteristics to the weld nugget; and (4) the particles containing intermetallic compounds act as dispersoids in the Al matrix. Quantitatively, the weld retained 98% (104.2 ± 3.3 MPa) UTS and 90% (17.1 ± 1.2) ductility of base aluminum, demonstrating the effectiveness of the Ni interlayer approach in controlling brittle intermetallic formation. Full article

A lightweight composite that simultaneously exhibits high strength and excellent thermal insulation is of great interest for thermal protection applications. In this study, dimensionally stable needled quartz fiber felt-reinforced phenolic aerogel composites were prepared using vacuum impregnation, sol–gel, and ambient pressure drying. The composites exhibit a multiscale porous structure formed by interconnected nanometer polymer skeletons and micronscale fibers. By regulating the thermoplastic phenolic resin concentration in the precursor solution, the pore structure of the material was refined; the average particle diameter reduced from 99.76 nm to 38.91 nm, and the average pore diameter decreased from 216.79 nm to 49.53 nm. At a phenolic resin concentration of 25%, the composite exhibits outstanding thermal insulation and mechanical properties: a low thermal conductivity of 0.0646 W·m⁻¹·K⁻¹ at room temperature, with a mere 19.5 °C temperature rise on the sample backside after 1800 s heating at 200 °C, and compressive strengths of 7.70 MPa in the XY-direction and 3.87 MPa in the Z-direction (at 10% strain). X-ray micro-CT characterized the internal structural evolution during loading, revealing a failure mechanism dominated by fiber buckling. Theoretical models and experimental data were used to analyze and quantify the contribution rates of gas and solid heat conduction in NQF/PR aerogel composites, with solid conduction accounting for over 80%. Combined with microstructural evolution, the mechanism for the high thermal insulation efficiency of NQF/PR aerogel composites was elucidated. This study prepared NQF/PR aerogel composites with promising application potential. By systematically evaluating their compressive behavior and quantifying the respective contributions of gas and solid conduction, this work provides a methodological framework to guide the rational design of similar aerogel composites. Full article

Despite extensive pore-scale studies on oil–water displacement, quantitative understanding of the dynamic evolution of residual oil morphology and waterflooding efficiency in geologically heterogeneous sandstones remains limited, particularly under large water-injection multiples. To better understand pore-scale oil–water distribution and its influence on enhanced oil recovery, this study utilized Micro-CT combined with SEM-EDS to examine the 3D pore structure and oil–water phase evolution in a heterogeneous sandstone sample from the Xiayang Formation, Wushi Sag, Zhanjiang. Mineralogical analyses reveal that dolomite cementation and vermicular kaolinite infilling introduce strong pore-scale heterogeneity by selectively reducing pore connectivity and permeability, posing challenges for uniform fluid displacement. A 30% KI solution was used to enhance X-ray attenuation of the aqueous phase, enabling clear discrimination between oil and water. Micro-CT reconstructions reveal a relatively uniform pore network dominated by medium-to-large intergranular pores. As the water-injection multiple increases, water progressively invades larger pores, while residual oil is immobilized by capillary forces within micro-throats, forming isolated clusters. The oil-droplet size distribution broadens from a narrow range (50–100 µm) to a wider one (200–300 µm), indicating interfacial destabilization and droplet coalescence. Quantitative analysis indicates that oil saturation decreases from approximately 90% to 36%, while waterflooding efficiency increases rapidly to ~45% at 1 PV and gradually approaches a plateau of ~60% beyond 500–1000 PV. This waterflooding plateau is attributed to capillary trapping and pore-scale connectivity limitations imposed by mineral-induced heterogeneity, which prevent further mobilization of residual oil despite continued water injection. This study advances pore-scale waterflooding research by combining mineralogical heterogeneity with long-term micro-CT imaging, revealing the pore-scale mechanisms controlling residual oil evolution and ultimate waterflooding limits in realistic sandstone. Full article

This study focuses on porous polyimide (PPI) lubricating materials for high-speed aerospace bearings. Based on their real microstructure, three-dimensional digital model reconstruction and mesoscale seepage characteristics were investigated. First, a sequence of two-dimensional slice images of PPI was obtained using micro-focus X-ray computed tomography (CT). Through image filtering, threshold segmentation, and three-dimensional reconstruction, a highly faithful digital model of the pore structure was constructed, and a quantified pore-network model was further extracted. Second, a multiple-relaxation-time lattice Boltzmann model based on the D3Q27 discrete scheme was established, and its accuracy and stability in complex boundaries and pressure-driven flows were verified using classic benchmark cases. Subsequently, the validated numerical model was applied to the reconstructed PPI pore structure to simulate and systematically analyze the single-phase seepage behavior of lubricating oil. The results show that the lubricant seepage exhibits a strong “preferential flow path” effect, with most of the flow transported through a small number of large-size throats. A clear quantitative relationship exists between the microscopic flow field structure—including velocity distribution, flow paths, and pressure gradient—and the pore-topology features, such as throat-size distribution, connectivity, and tortuosity. This verifies the mesoscale mechanism that “structure governs flow.” The complete technical chain established in this work—“real-structure reconstruction–numerical model validation–seepage mechanism analysis”—provides a reliable theoretical and numerical tool for gaining deeper insight into the lubricant transport behavior in porous polyimide and offers guidance for the microstructural design and optimization of this material. Full article

This study investigates the development of advanced protective gloves by applying novel 3D-printed PET-G mesh overlay structures onto three textile substrates—polyamide (PA), polyester (PES), and cotton—using ultrasonic welding and contact welding. The focus was on assessing weld quality, thickness uniformity, and functional durability. Weld morphology and bonding integrity were evaluated using X-ray microtomography (micro-CT), while bending fatigue tests assessed mechanical performance under cyclic loading. The results show that ultrasonic welding produces more uniform welds, enhancing fatigue resistance, particularly on cotton and polyamide substrates. Non-uniform welds with thicker or uneven areas, typical of contact welding, correlated with reduced mechanical durability. These findings highlight the potential of additively manufactured overlay structures for hybrid protective gloves, demonstrating that weld thickness uniformity and substrate compatibility are key factors in optimizing mechanical performance. This work extends our previous research by introducing new 3D-printed overlay architectures and provides valuable insights into the practical implementation of additively manufactured polymeric structures in PPE development. Full article

Quantification of total porosity, including the nano-scale fraction, is critical for predicting the performance of cement-based materials but remains a significant challenge. While X-ray computed tomography (CT) is a powerful non-destructive tool, a fundamental trade-off between resolution and representative sample volume prevents the direct segmentation of nano-scale pores in macroscopically relevant specimens. Herein, we propose and validate a novel model-informed framework that overcomes this limitation by integrating the classical Powers’ hydration model with micro-CT analysis. The method circumvents the need for nano-scale resolution by deriving the total porosity from the volume fraction of the easily segmentable, micron-scale unhydrated cement phase. The framework’s validity was demonstrated by showing a strong correlation between the CT-derived total porosity and established porosity–strength relationships. Quantitative analysis indicated that the total porosity of the cement pastes ranged from 36.5% to 60.3% as the w/c ratio increased from 0.4 to 0.7. Laboratory strength data show good correlation (R² > 0.98) with four porosity–strength prediction models, demonstrating the feasibility of applying the Powers’ volume model in CT-based analyses of cement pastes. This work transforms micro-CT from a qualitative imaging tool into a comprehensive technique for the quantitative microstructural characterization of cementitious materials. Full article

The Esquel pallasite provides a valuable record of metal–silicate interaction in differentiated planetesimals, yet many aspects of its formation and thermal evolution remain uncertain. Here, we present a comprehensive multi-technique characterization of a single Esquel specimen, integrating SC-XRD, Raman spectroscopy, SEM–EDS, XPS, magnetic force microscopy, and X-ray computed tomography. Olivine grains are shown to be structurally pristine, with the first full crystallographic refinement for Esquel confirming a single-domain silicate lattice. XPS demonstrates a stoichiometric silicate surface containing only lattice O²⁻, Si⁴⁺, Mg²⁺, and Fe²⁺, indicating that olivine remained chemically unaltered. The Fe–Ni metal preserves diffusion-controlled taenite–kamacite exsolution, compositionally distinct plessite, accessory schreibersite and troilite as resolved by SEM. Quantitative Ni zoning, evaluated through interface-to-center gradients and a width–center-Ni correlation method, yields a self-consistent cooling rate of ~10–20 °C/Myr. MFM reveals microscale magnetic structures that correlate directly with Fe–Ni chemical zoning, providing magnetic confirmation of slow cooling. CT analysis further identifies interconnected metal networks, inclusions, and micro-porosity reflecting melt migration and late-stage modification. These results establish Esquel as an exceptionally well-preserved pallasite and demonstrate the value of integrated, multi-scale analytical workflows for reconstructing early Solar System processes. Full article

The textile industry generates significant volumes of waste, making the development of reliable methods to evaluate biodegradability a pressing need. While standardised protocols exist for plastics, no specific methodologies have been established for textiles, and the quantification of non-degraded residues is commonly based on mass loss: a measurement that is prone to recovery errors. This study investigated the biodegradation of cotton, polyester, and cotton/polyester blend fabrics in soil under thermophilic conditions using a combined methodological approach. Carbon mineralisation was quantified through a respirometric assay that was specifically adapted for textile substrates, while residual solid fractions were assessed in situ by X-ray microtomography (micro-CT), thus avoiding artefacts associated with sample recovery. Complementary analyses were performed using SEM and FTIR to characterise morphological and chemical changes. Results showed substantial biodegradation of cotton, negligible degradation of polyester, and intermediate behaviour for the cotton/polyester blend. Micro-CT enabled the visualisation of fibre fragmentation and the quantification of the residual. The integration of respirometric, imaging, and spectroscopic techniques provided a comprehensive assessment of textile biodegradability. This study highlights the potential of micro-CT as a non-destructive tool to improve the accuracy and robustness of textile biodegradability assessment by enabling direct quantification of the residual solid fraction that can support future LCA studies and the development of standardised protocols for textile biodegradability. Full article

Characterizing tight reservoirs is challenging due to the complex pore structure and strong heterogeneity at various scales. Current digital rock physics often struggles to reconcile high-resolution imaging with representative sample sizes, and 3D digital cores are frequently used primarily as visualization tools rather than predictive, computable platforms. Thus, a clear methodological gap persists: high-resolution models typically lack macroscopic geological features, while existing 3D digital models are seldom leveraged for quantitative, predictive analysis. This study, based on a full-diameter core sample of a single lithology (gray-black shale), aims to bridge this gap by developing an integrated workflow to construct a high-fidelity, computable 3D model that connects the micro–nano to the macroscopic scale. The core was scanned using high-resolution X-ray computed tomography (CT) at 0.4 μm resolution. The raw CT images were processed through a dedicated pipeline to mitigate artifacts and noise, followed by segmentation using Otsu’s algorithm and region-growing techniques in Avizo 9.0 to isolate minerals, pores, and the matrix. The segmented model was converted into an unstructured tetrahedral finite element mesh within ANSYS 2024 Workbench, with quality control (aspect ratio ≤ 3; skewness ≤ 0.4), enabling mechanical property assignment and simulation. The digital core model was rigorously validated against physical laboratory measurements, showing excellent agreement with relative errors below 5% for key properties, including porosity (4.52% vs. 4.615%), permeability (0.0186 mD vs. 0.0192 mD), and elastic modulus (38.2 GPa vs. 39.5 GPa). Pore network analysis quantified the poor connectivity of the tight reservoir, revealing an average coordination number of 2.8 and a pore throat radius distribution of 0.05–0.32 μm. The presented workflow successfully creates a quantitatively validated “digital twin” of a full-diameter core. It provides a tangible solution to the scale-representativeness trade-off and transitions digital core analysis from a visualization tool to a computable platform for predicting key reservoir properties, such as permeability and elastic modulus, through numerical simulation, offering a robust technical means for the accurate evaluation of tight reservoirs. Full article

Lacustrine shale oil in the Chang 7 Member of the Ordos Basin is controlled by a multi-scale pore–throat system in which oil occurrence, spontaneous imbibition, and pore-structure evolution are tightly coupled. In this study, nitrogen adsorption and micro-computed tomography (μCT) were employed to characterize pore-size distribution and connectivity, whereas nuclear magnetic resonance (NMR) T₂ relaxation was utilized to classify oil occurrence states, and X-ray diffraction (XRD) and total organic carbon (TOC) analyses were performed to determine mineralogical and organic compositions. Spontaneous imbibition experiments were conducted at 60 °C and subsequently extended to temperature–pressure sequence tests. The Chang 7 shale exhibits a stratified pore system in which micropores, mesopores, and macropores jointly define a three-tier “micropore adsorption–mesopore confinement–macropore mobility” pattern. As pore size and connectivity increase, the equilibrium imbibed mass and initial imbibition rate both rise, while enhanced wettability (contact angle decreasing from 81.2° to 58.7°) further strengthens capillary uptake. Temperature elevation promotes imbibition, whereas increasing confining pressure suppresses it, revealing a “thermal enhancement–pressure suppression” behavior. μCT-based network analysis shows that imbibition activates previously ineffective pore–throat elements, increasing coordination number and connectivity and reducing tortuosity, which collectively represents a capillary-driven structural reconfiguration of the pore network. When connectivity exceeds a threshold of about 0.70, the flow regime shifts from interface-dominated to channel-dominated. Building on these observations, a multi-scalecoupling framework and a three-stage synergistic mechanism of “pore-throat activation–energy conversion–structural reconstruction” are established. These results provide a quantitative basis for predicting imbibition efficiency and optimizing capillary-driven development strategies in deep shale oil reservoirs. Full article

This in vitro study investigated the fracture resistance of three ceramic-reinforced polymer (CRP) crowns—Cerasmart^® 270 (CE; milled), VarseoSmile Crown Plus^® (VS; 3D-printed) and the newly developed Hassawat-01 (HS; 3D-printed)—luted with cements of different elastic moduli. The principal hypothesis was that neither the CRP type nor the modulus of cement would significantly affect fracture resistance. Ninety-nine mandibular first molar resin dies were restored with 1 mm thick CE, VS, or HS crowns (n = 33 each) and luted with Maxcem Elite^®, RelyX Unicem^®, or Ketac Cem^® (n = 11 per subgroup). Occlusal cement morphology was evaluated using Micro-CT. Fracture resistance was measured using a universal testing machine. Crowns luted with Maxcem or RelyX withstood forces >2000 N without visible failure. Ketac-luted crowns showed reduced fracture resistance. CE-Ketac fractured in 4 of 11 specimens. VS-Ketac exhibited cracks or complete fractures (1795.2 ± 156.7 N), whereas HS-Ketac showed only superficial cracking (1732.6 ± 127.3 N). CRP crowns luted with lower-modulus resin cements demonstrated superior fracture resistance compared with those luted with glass-ionomer. VS exhibited both cracking and occasional complete fractures, whereas HS exhibited only surface cracking. All materials withstood loads greater than typical masticatory forces, supporting HS as a promising alternative within the CRP. Full article

This paper provides a comprehensive overview of the application of various radiological modalities, with a critical comparison between human and veterinary medicine. The modalities discussed include conventional radiography, dual-energy X-ray absorptiometry (DXA), computed tomography (CT), magnetic resonance imaging (MRI), ultrasound (US), quantitative ultrasound (QUS), positron emission tomography-computed tomography (PET-CT) and micro and nano computed tomography (micro-CT, nano-CT) in clinical practice and basic research of skeletal system. Radiological imaging plays a crucial role in the diagnosis, monitoring and research of skeletal system disorders in both human and veterinary medicine. In preclinical research, advanced diagnostic imaging modalities such as micro-CT and nano-CT allow for 3D quantification of trabecular and cortical bone microarchitecture for studies in bone biology, regenerative medicine and pharmacological research. Furthermore, the integration of artificial intelligence is advancing image interpretation, precision diagnostics and disease tracking. Despite their broad utility, imaging modalities must be selected based on clinical indication, species, age and anatomical region with consideration of radiation dose, cost and availability, especially in remote regions. For this reason, clinicians and radiologists remain an irreplaceable part of diagnostic imaging. Full article

Background: Bone fracture is a partial or complete break in the continuity of a bone, which poses a significant healthcare burden. It is important to discover a novel method to stimulate and speed-up the healing of bone fractures. Aim: This study aimed to investigate the effects and mechanisms of alternating current (AC) in promoting bone fracture healing. Methods: A rabbit bone fracture model was used. X-ray and Micro-CT evaluated fracture healing, while HE staining and immunohistochemistry assessed morphological changes. In vitro, pre-osteoblastic cells were tested with alizarin red S staining and alkaline phosphatase (ALP) activity. RNA-seq analysis explored potential mechanisms. Results: X-ray evaluation showed that alternating current stimulation (ACS) promoted bone formation and shaping by day 14 post-treatment. Micro-CT results revealed significant new bone formation as early as day 3 and day 7 (p < 0.05). HE staining indicated more trabecular bone formation in the ACS group compared to the model group at days 7 and 14. Immunohistochemistry showed higher expression of BMP-2 and VEGF in the ACS group by day 7. In vitro, ACS enhanced osteogenic differentiation, increasing calcified nodule formation and ALP activity. Gene expression analysis demonstrated significant changes in key osteogenic genes, confirmed by multiple immunohistochemical staining. Conclusions: ACS may be a novel method for treating bone fractures more rapidly, significantly relieving the patient’s burden, particularly in the early stages of bone healing. Full article

Additive manufacturing (AM) has rapidly evolved due to its design flexibility, ability to enable personalized fabrication, and reduced material waste. In the medical field, fused filament fabrication (FFF) facilitates the production of individualized anatomical models for surgical preparation, education, medical imaging, and calibration. However, the lack of filaments with X-ray attenuation similar to that of biological hard tissues limits their use in radiological imaging. To address this limitation, a radiopaque filament was developed by incorporating gadolinium oxide (Gd₂O₃) into a biodegradable poly(lactic acid) (PLA) matrix at 1, 3, and 5 wt.%. Thermal and rheological properties were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and melt flow index (MFI) analyses, revealing minor variations that did not affect printability under standard FFF conditions (200 °C nozzle, 60 °C build plate, 0.12 mm layer height). Microstructural analysis via field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), elemental mapping, and micro-computed tomography (micro-CT) confirmed homogeneous Gd₂O₃ dispersion without nozzle blockage. Radiopacity was evaluated using gyroid infill cubes, and increasing Gd₂O₃ content enhanced X-ray attenuation, with 3 wt.% Gd₂O₃ reaching Hounsfield Unit (HU) values comparable to cortical bone. Finally, the L1 vertebra phantom fabricated from the 3 wt.% Gd₂O₃ filament exhibited mean HU values of approximately +200 to +250 HU at 50% infill density (trabecular bone region) and around +1000 HU at 100% infill density (cortical bone region), demonstrating the filament’s potential for producing cost-effective, radiopaque, and biodegradable phantoms for computed tomography (CT) imaging. Full article

Alzheimer’s disease (AD) and osteoporosis frequently co-occur in the elderly; however, the pathophysiological link between these two diseases remains unclear. This study investigates skeletal alterations in a triple transgenic 3xTg-AD mouse model of AD (3xTg-AD), which harbors mutations in β-amyloid precursor protein (βAPP_Swe), presenilin-1 (PS1_M146V), and tau_P301L, and recapitulates key aspects of AD pathology, including age-dependent β-amyloid plaque accumulation and cognitive decline. To assess early skeletal changes, we analyzed femurs and tibiae of 2-month-old male non-Tg and 3xTg-AD mice (n = 9/group) using micro-CT. Despite the absence of β-amyloid plaques at this stage, 3xTg-AD mice showed significant cortical bone loss, with reduced bone surface, periosteal and endosteal perimeters, total and cortical cross-sectional area, and polar moment of inertia. The 3-point-bending test confirmed compromised mechanical properties, including reduced maximum load-to-fracture and stiffness. Histological analyses highlighted an increased number of Empty Osteocyte Lacunae, reduced TRAP⁺ osteocytes, and an elevated number of osteoclasts; such evidence indicates impaired osteocyte function and increased bone resorption. These findings indicate that cortical bone loss and compromised mechanical properties occur before detectable neuropathological hallmarks in this AD model. Full article