Search Results (961)

Composite specimens of normal concrete (NC) and ultra-high performance concrete (UHPC) in marine tidal zones are susceptible to coupled physico-chemical degradation under seawater wet–dry cycling; however, the microscopic damage-evolution mechanisms within the NC/overlay transition zone (OTZ)/UHPC three-phase region remain unclear. In this study, accelerated erosion was conducted using 10-fold concentrated artificial seawater under 0, 30, 60, and 90 wet–dry cycles. The X-ray computed tomography, mercury intrusion porosimetry, backscattered electron imaging coupled with energy dispersive X-ray spectroscopy and slant shear tests were employed to systematically investigate the macroscopic bonding performance and microscopic structural damage of NC-UHPC composites. The results show that the interfacial bond strength initially increases and then declines, exhibiting a 13.53% improvement after 30 wet–dry cycles and a sharp 41.55% decrease after 90 cycles compared with that after 60 cycles. The damage severity was the highest in NC, intermediate in OTZ, and lowest in UHPC. The gas-rich pore region within the OTZ provides a stress-buffering effect during the early stage of corrosion. After 90 wet–dry cycles, the total porosity increased by 0.14%, with external porosity increasing by 0.21% and internal porosity decreasing by 0.07%, indicating a pore-structure reconfiguration characterized by micropore coalescence and an increased proportion of macropores. These findings clarify the damage process associated with seawater erosion, pore expansion, and interfacial failure, providing theoretical support for the repair design and durability assessment of marine concrete structures. Full article

Recent deep exploration in the northern Sichuan Basin has advanced our understanding of Lower Cambrian Canglangpu Formation carbonate reservoirs. However, the characteristics, genesis, and distribution of the reservoir, as well as future exploration targets, remain unclear. Specifically, core and thin-section analyses indicate that these reservoirs are notably tight, with virtually no visible macroporosity and low permeability (0.01–1 mD). However, helium porosity measurements reveal values of 2–5%, suggesting significant storage potential. An integrated approach utilizing optical and scanning electron microscopy (SEM), high-pressure mercury injection capillary pressure (MICP), nuclear magnetic resonance (NMR), and micro-computed tomography (micro-CT) was employed to characterize the pore systems. Quantitative thin-section analysis reveals visible areal porosity markedly lower than helium porosity, indicating predominance of micropores; mercury intrusion and NMR demonstrate that intragranular and intergranular micropores constitute most pore volume, although effectively connected throat sizes remain below 1 µm. Comparative stratigraphic evaluations show that porosity is more developed in the dolomite-rich upper and middle intervals of the depositional cycles, whereas the lower intervals are less porous. Early subaerial exposure promoted dolomitization and dissolution, which facilitated pore development. However, the influence of sediment mixing led to a reduction in porosity. And deep burial subjected the rocks to intense compaction and cementation, destroying most of the primary pore space. Consequently, reservoir quality is ultimately governed by the interplay between the original depositional environment and the later diagenetic history, with paleotopographic highs identified as the most promising exploration targets. These findings establish a predictive framework for reservoir quality in tight carbonate rocks, which holds significant implications for analogous plays worldwide. Full article

To investigate the effects of incorporating nanomaterials—carbon nanotubes (CNTs) and graphene oxide (GO)—on the axial compressive mechanical properties of alkali-activated recycled aggregate concrete (AARAC) after high-temperature exposure, this study designed 51 sets of specimens with recycled coarse aggregate replacement rate, nanomaterial content, and temperature as the main parameters. Compression tests were conducted to analyze the failure mode and strength variation in AARAC specimens after heating. In addition, microscopic tests, including X-ray diffraction, scanning electron microscopy, and computed tomography (CT scanning), were performed to analyze the microstructural characteristics of the post-heated AARAC specimens. The results indicate that as the replacement rate of recycled coarse aggregate increased from 0% to 100%, the residual compressive strength after exposure to 600 °C decreased from 33.6 MPa to 19 MPa. When 0.1 wt% of CNTs is added, the compressive strength of AARAC after exposure to a high temperature of 600 °C increases by approximately 30.4% compared to that of AARAC without nanomaterial addition. When 0.1 wt% of CNTs and 0.05 wt% of GO are added, the compressive strength after exposure to a high temperature of 600 °C increases by approximately 44.3%, while the size of scattered fragments upon failure increased, and the failure mode appeared more complete. Microscopic test results indicate that the high-temperature treatment did not cause significant changes in the main phase composition of AARAC. The synergistic effect of the nanomaterials CNTs and GO can fully utilize their functions as nucleation sites, pore fillers, and crack bridging agents. By strengthening the Interfacial Transition Zone between the recycled coarse aggregate and the cement paste, refining the Matrix Pore Structure, dispersing local thermal stress, and suppressing the propagation of high-temperature cracks, the mechanical properties of AARAC after high-temperature exposure can be effectively maintained. Full article

TiN/CrAlN multilayer coatings were synthesized by cathodic arc deposition using 2-fold substrate rotation and alternating targets. The effect of substrate rotation on the layer sequence, elemental fluctuations and interface quality was examined using high-resolution transmission electron microscopy and atom probe tomography. The layers exhibited semi-coherent growth across the interfaces. Minor interface roughness and elemental intermixing limited to below 2 nm at the interface could be observed. Further, the formation of a Ti-enriched sublayer in the Cr_1−xAl_xN as a result of the 2-fold rotation was identified. Full article

Background: Cardiac implantable electronic device (CIED) lead perforation is a rare but potentially catastrophic complication. As global device implantations increase, understanding the clinical spectrum and optimal management of this complication is essential. This study characterizes the clinical presentation, diagnostic strategies, and outcomes of lead perforation over a 25-year period. Methods: A retrospective analysis was conducted on 32 patients diagnosed with CIED lead perforation between 2000 and 2025 at a high-volume center. Perforations were classified by timing: acute (<24 h), subacute (1–30 days), and chronic (>30 days). Data included demographics, comorbidities, imaging modalities, and procedural interventions. Results: The mean patient age was 76.0 ± 11.7 years, with a mean body mass index (BMI) of 25.5 ± 3.4 kg/m². Subacute presentation was the most frequent (59.3%, n = 19), followed by acute (28.1%, n = 9) and chronic (12.5%, n = 4) cases. The right ventricle was the primary site of perforation (90.6%). While chest X-rays served as an initial screening tool in 62.5% of cases, diagnosis relied on multimodal imaging, with Computed Tomography (CT) providing definitive confirmation in 31.3% of the cohort, particularly when lead parameters remained stable. Management was risk-stratified based on hemodynamic status. The majority of patients (71.9%, n = 23) underwent successful transvenous lead removal via simple traction. However, 25% (n = 8) presented with hemodynamic instability, and 21.9% (n = 7) suffered from cardiac tamponade. These high-risk cases required surgical intervention, including sternotomy (n = 4), thoracotomy (n = 2), or pericardiotomy (n = 3). Notably, 62.5% of hemodynamically unstable patients were on oral anticoagulants. All patients survived to discharge, with no in-hospital mortality. The median length of hospital stay was 3 days. Conclusions: CIED lead perforation often presents subacutely with subtle clinical signs. CT imaging has emerged as the gold standard for definitive diagnosis. While percutaneous transvenous removal is safe and effective for stable patients, immediate surgical backup is vital, as patients—particularly those on anticoagulation—can deteriorate rapidly. Full article

This study presents a comprehensive characterization of Argopecten purpuratus (AP) shells—a marine-derived natural bioceramic composed predominantly of calcium carbonate (CaCO₃)—to evaluate their potential as biomaterials for regenerative medicine. Structural and compositional analyses were performed using micro-computed tomography (MicroCT), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). These techniques confirmed a high CaCO₃ content (>96 wt%) and revealed distinct microstructural features: the outer surface showed irregular grooves and rough textures, while the inner surface exhibited smoother, foliated morphologies with mixed calcite and aragonite phases. To assess biocompatibility, human gingival mesenchymal stem cells (hGMSCs) were cultured on both shell surfaces. Viability and adhesion were evaluated via MTS assays and fluorescence microscopy at time points ranging from 30 min to four weeks. Both surfaces supported robust early metabolic activity and long-term proliferation, with cells covering the entire surface area after four weeks. Morphometric analysis indicated time-dependent changes in cell shape, transitioning from rounded to elongated morphologies, with minor differences linked to surface topography. The integration of structural, compositional, and biological data demonstrates that AP shells provide a cytocompatible and sustainable natural material platform capable of supporting cell adhesion and proliferation. Their inherent micro- and nanoscale surface features may facilitate protein adsorption and cell–material interactions. These findings highlight the importance of correlating microstructural material properties with cellular responses and support the future exploration of marine-derived bioceramics for regenerative medicine applications. Full article

This study proposes a four-dimensional Historical Building Defect Information Modeling (HBDIM) framework designed to support the documentation, diagnosis, and conservation of deteriorated historic stucco elements. The framework integrates multi-source digital documentation techniques, including terrestrial laser scanning (TLS), high-resolution photogrammetry, and automated total station measurements with laboratory-based material diagnostics to create a unified digital environment for defect detection and conservation assessment. The approach was applied to the Baron Empain Palace in Egypt as a representative case study of complex architectural heritage affected by material deterioration. Within the HBDIM workflow, point cloud processing and defect-oriented information modeling were used to identify and spatially localize deterioration features such as cracking, erosion, and material loss. Laboratory investigations—including computed tomography (CT), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray fluorescence (XRF)—were conducted to evaluate the effectiveness of calcium hydroxide nanoparticle consolidation treatments and to relate microstructural material behavior to spatially mapped defects within the digital model. Mechanical testing demonstrated a significant improvement in material performance, with treated stucco samples exhibiting an average compressive strength increase of approximately 69.06% compared to untreated specimens. The results demonstrate that integrating digital documentation, defect-oriented modeling, and material diagnostics within a four-dimensional framework provides a robust platform for linking geometric deterioration patterns with material-level conservation performance. By embedding diagnostic data and treatment outcomes within a temporally structured digital model, the HBDIM approach supports preventive conservation strategies, long-term monitoring, and data-driven decision-making in sustainable heritage management. Full article

Cardiac sarcoidosis (CS) is a critical and frequently underdiagnosed phenotype of sarcoidosis, characterized by non-caseating granulomatous infiltration of the myocardium. This review synthesizes current knowledge regarding the pathogenesis, diagnosis, and management of CS. The disease manifests with a heterogeneous clinical spectrum ranging from asymptomatic conduction abnormalities to life-threatening ventricular arrhythmias and heart failure. Diagnosis remains challenging due to the patchy distribution of granulomas, which limits the sensitivity of endomyocardial biopsy. Consequently, a multimodal diagnostic approach is essential, integrating advanced imaging modalities such as cardiac magnetic resonance (CMR) with late gadolinium enhancement (LGE) and ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET). These tools not only facilitate detection but also enable the differentiation of active inflammation from chronic fibrosis. Histopathological assessment, supported by specific immunophenotyping and electron microscopy, remains the gold standard for confirming diagnosis and excluding mimics like giant cell myocarditis or infectious granulomatous diseases. Management requires a multidisciplinary strategy combining immunosuppressive therapy, primarily corticosteroids and steroid-sparing agents, with guideline-directed cardiac care, including implantable cardioverter-defibrillators for arrhythmia risk stratification. Emerging biomarkers and artificial intelligence-driven imaging analysis promise to further refine risk stratification and therapeutic monitoring, advancing precision medicine in this complex disorder. Full article

Silica-based bioceramics are promising bone substitutes with tunable degradation and mechanical properties. We aimed to assess bone response in critical-size calvarial defects in rats, empty or filled with 3D-printed sphene ceramic (CaTiSiO₅) scaffolds produced using direct ink writing from preceramic polymers and reactive fillers. Scaffold characterization was performed using scanning electron microscopy, X-ray diffraction, porosity analysis, and compressive strength testing. Bilateral cylindrical 5 mm calvarial defects were created in 20 rats: one was randomly filled with sphene scaffold, while the contralateral remained empty. Ten animals were killed at 4 weeks, the rest at 8 weeks. Specimens were collected for micro-X-ray computed tomography (micro-CT) analysis, followed by undecalcified histology. The scaffolds exhibited porous structure with complete sphene phase purity and compressive strength of 17.91 MPa (SD 4.6). In vivo, no adverse event was noted during healing. Overall bone regeneration—as measured by BV/TV—was comparable between groups: Bone volume/total volume (BV/TV) increased over time in the empty and sphene groups, reaching ~40%, with no significant differences between groups or time points. BV/TV was significantly higher in the external regions of the defects compared to the internal areas in both groups at the two time points. The sphene group showed a significantly greater volume of new bone extending beyond the original cortical boundary at both 4 and 8 weeks (p = 0.013). In the sphene group histology revealed partial bone ingrowth within the scaffold, while bone in the control group was limited to defect edges. After 8 weeks, new bone adjacent to the cortical surface was thicker in the sphene group (p < 0.05). These initial findings are consistent with prior preclinical studies, supporting the biocompatibility and osteoconductive nature of sphene ceramic scaffolds. Full article

The study investigates the microstructure evolution in the stir zone produced by the friction stir processing (FSP) of a heat-treated microalloyed Al-Mn-Cu alloy in the area subjected to the highest temperature, strain, and strain rate. The samples were studied using electron microscopy and atom probe tomography (APT) to obtain structural and chemical information from the macro to the nano scale. FSP refines the dendritic Al-rich solid solution grains through dynamic recrystallisation in the range of a few micrometres. The primary intermetallic phases were dispersed to the particles in the 0.5–3 µm range and transformed mainly into a more stable τ₁-Al₂₉Mn₆Cu₄ phase. The fraction of dispersed particles after FSP increased due to the precipitation from the solid solution during cooling. The nanoscale quasicrystalline precipitates in the matrix, formed upon heat treatment, dissolved entirely during FSP, while the strong coarsening of the L1₂ precipitates occurred due to high temperatures in the stir zone. After FSP, the hardness of the stir zone was nearly identical for specimens in the as-cast and heat-treated conditions. Full article

This study develops a multi-scale fiber-reinforced cementitious composite (MFRC) by hybridizing calcium carbonate whisker (CW), polyvinyl alcohol (PVA) fiber, and steel fiber. The interfacial micromechanical properties between steel fiber/matrix and PVA fiber/matrix under the influence of CW were systematically examined through single-fiber pull-out tests. The two-dimensional and three-dimensional distribution characteristics of fibers in the MFRC were analyzed using backscattered electron imaging (BSE) and X-ray computed tomography (X-CT), respectively. Based on the fiber distribution characteristics, flexural strength prediction models were developed with R² values of 0.79 (2D) and 0.82 (3D). Experimental validation via splitting tensile tests and three-point bending tests confirmed the model’s effectiveness in simultaneously predicting splitting tensile strength (R² = 0.89) and flexural strength (R² = 0.93). These findings demonstrate the reliability and universality of the proposed model for predicting flexural–tensile strength in an MFRC. Full article

The Tianfu Gas Field in the Sichuan Basin is a core block for the large-scale, economic development of Jurassic tight gas in China. The first sub-member of the first member of the Shaximiao Formation in the Zhongjiang Block hosts typical low-porosity and low-permeability tight sandstone reservoirs. Based on detailed field geological surveys and core observations, this study employed multiple technical methods, including cast thin sections, scanning electron microscopy, computed tomography (CT) scanning, and nuclear magnetic resonance (NMR) to investigate sedimentary microfacies’ characteristics, analyze key reservoir properties (e.g., reservoir space types and pore structure), and clarify the main controlling factors of reservoir development. The results indicate the following: (1) The sedimentary period of the first sub-member of the first member of the Shaximiao formation (Es₁¹) was controlled by a subtropical humid climate, with widespread gray mudstones and bedding-parallel plant fossil fragments. The main sedimentary environment was a shallow-water delta front, where the underwater distributary channel microfacies was the dominant facies belt. (2) Reservoir lithology is dominated by lithic arkose and feldspathic litharenite, with low compositional and structural maturity. Residual primary intergranular pores are the dominant reservoir space type, followed by intragranular dissolved pores in feldspar and lithic fragments. (3) The pore structure is characterized by a small pore-throat radius, poor sorting, and strong heterogeneity. Reservoirs can be subdivided into three categories, with Types II and III being the main types developed in this block. (4) Underwater distributary channels of the shallow-water delta are the main occurrence of reservoir sand bodies. During the burial diagenetic stage, calcite and laumontite cementation and filling led to reservoir densification. Meanwhile, early-formed chlorite rim cement effectively protected primary pores by inhibiting grain compaction and quartz overgrowth. Superimposed with the dissolution and alteration of feldspar, lithic fragments, and other components by late acidic fluids, effective pores were further expanded. The synergistic coupling of these sand-controlling factors and the “densification–protection–alteration” diagenetic process jointly constitutes the formation mechanism of high-quality reservoirs. This mechanism can provide a reliable theoretical basis for the accurate prediction of reservoir “sweet spots” and the optimal selection of horizontal well targets in the Zhongjiang Block of the Tianfu Gas Field. Full article

Background/Objectives: This article develops theory and methods for 3D tomographic imaging of absorption coefficient distributions using axial scanning with EUV microscopes at 46× and 345× magnification. Unlike conventional CT that requires sample rotation, axial scanning moves cells through the microscope focus. The aim is tomographic reconstruction of living cell fine structure without the organelle staining used in optical fluorescence microscopy or ultra-thin cell slicing as in electron microscopy. Methods: By generalizing the geometric-optical approximation for small absorption coefficient inhomogeneities in absorbing media, we derived a new explicit tomography equation and solution algorithm validated through numerical simulation. The approach was applied to Convallaria cell analysis using the ×46 microscope. For the ×345 microscope, we developed an alternative method where the kernel of the tomography integral equation was determined experimentally using gold nanospheres with known absorption coefficient, shape, and position. This method was tested through modeling and applied to diagnostics of Convallaria and mouse cerebellar granule cells. Results: The developed methods resolve subcellular features down to 140 nm using the ×46 microscope and 50 nm using the ×345 microscope. Thin low-contrast intracellular structures and individual 50–100 nm organelles were detected. Conclusions: Methods for retrieving absorption coefficient distributions in cone-beam geometry based on geometric-optical theory generalization and on calibration by gold nanoparticles have been developed and validated through numerical simulation and cell analysis. These methods demonstrate for the first time the effectiveness of axial nanotomography using multilayer mirror microscopes for cell diagnostics. Full article

This study examines the carbonation behavior and CO₂ storage potential of a Ca-rich alkali-activated binder produced entirely from industrial residues-ladle furnace slag (LFS), coal ash (CA), and cement kiln dust (CKD). The system was designed as a one-part alkali-activated material (AAM), with CKD acting as an internal activator, and subjected to ambient curing, water curing, and accelerated CO₂ curing at ambient pressure. Phase evolution, microstructural development, and pore-structure characteristics were investigated using X-ray diffraction, FTIR spectroscopy, DSC–TG analysis, scanning electron microscopy, and X-ray micro-computed tomography, together with measurements of density, water absorption, and compressive strength. Loss-on-ignition measurements combined with chemical analysis were further used to quantify CO₂ uptake and evaluate the degree of carbonation of the binder system. CO₂ curing fundamentally altered the reaction pathway of the binder, shifting it from hydration-dominated to carbonation-controlled phase evolution, leading to the decomposition of calcium-bearing hydrates and complete carbonation of non-hydraulic γ-belite with the formation of vaterite, aragonite, and calcite. These transformations induced pronounced microstructural densification, reflected in a near-doubling of compressive strength (>48 MPa), increased apparent density, reduced water absorption, and simplified pore-network topology. A preliminary carbon footprint assessment indicates that the production of 1 m³ of the developed LFS–CA–CKD concrete generates about 14.36 kg CO₂-eq, while the carbonation process enables significant CO₂ sequestration, resulting in a net negative carbon balance. The results demonstrate that controlled carbonation is an effective post-treatment strategy for waste-derived alkali-activated binders, enabling simultaneous performance enhancement and permanent CO₂ sequestration. Full article

Electrical Impedance Tomography (EIT) represents a promising and non-invasive technique for the characterisation of biological tissues, but its diagnostic performance strongly depends on the electrode configuration, system geometry, and electronic acquisition strategies. In this work, a three-dimensional model based on the Finite Element Method (FEM) is developed to investigate the detectability of epithelial neoplasms through optimised electrode excitation schemes. The adjacent and opposite configurations are systematically compared in terms of impedance contrast, spatial sensitivity, and neoplastic inclusion localisation capability. The simulations were implemented using an open-source finite element solver with heterogeneous multilayer tissue models. The results show that the configuration with opposite electrodes significantly improves impedance contrast and sensitivity in three-dimensional models, allowing for better detection of localised conductivity anomalies. The proposed approach contributes to the design of optimised EIT electronic systems for early and non-invasive screening applications of epithelial cancer. Full article