Search Results (2,863)

Chondroblastoma is a generally benign tumor occurring at a young age; however, its location near a joint and its tendency to recur make the treatment particularly challenging. This is especially true in the case of its occurrence in the hip joint. Surgical removal—curettage—is the primary method, but the remaining defect can be filled with several methods depending on the size of the tumor. The approach to the lesion is another difficulty. There are several available options, but due to the characteristics of the blood supply to the joint, this is a significant risk. In our case, we used an open autologous osteochondral graft transplantation (mosaicplasty) to treat juvenile hip chondroblastoma in a young female patient, for which the ipsilateral knee joint served as the donor area. The patient was followed up for 3 years after surgery, and, in addition to physical examinations, numerous imaging studies were performed to exclude local recurrence or avascular necrosis in the femoral head and to ensure that the congruence of the implanted osteochondral grafts was maintained. Full article

Yellow and pink calcite samples from the Huanggangliang and Xilingol mining areas in Inner Mongolia were investigated to elucidate the relationships among chemical composition, unit-cell parameters, coloration, and luminescence. Electron probe micro-analysis, laser ablation inductively coupled plasma mass spectrometry, X-ray diffraction, infrared spectroscopy, Raman spectroscopy, UV-Vis absorption spectroscopy, and photoluminescence measurements show that samples of yellow and pink calcite differ significantly in impurity incorporation and optical behavior. Yellow calcite is relatively enriched in Mg and rare earth elements, especially Y and Ce, whereas pink calcite contains markedly higher Mn and Fe contents. The pink calcite has smaller lattice parameters and unit-cell volume, consistent with greater substitution of Ca²⁺ by smaller-radius cations. Spectra reveal that the pink coloration is mainly related to Mn-associated absorption bands at 402 and 527 nm, whereas the yellow color is attributed to weak impurity- and defect-related absorption. Under ultraviolet excitation, yellow calcite exhibits a broad blue–white emission centered at ~470 nm, whereas pink calcite shows an intense orange–red emission near 625 nm characteristic of Mn²⁺. Variable-temperature photoluminescence further demonstrates that the pink calcite has higher thermal stability, with a thermal-quenching activation energy of 0.218 eV, compared with 0.074 eV for the yellow calcite. These results demonstrate that trace element incorporation plays a key role in regulating the coloration and luminescence of calcite and provide useful insight into the optical behavior of carbonate minerals. Full article

Mitochondria are vital organelles for human cells with fundamental roles in major metabolic processes such as calcium homeostasis, ATP production, apoptosis and signal transduction. Defective morphology and activity of these organelles have been tightly associated with the pathological onset of severe human disorders, including cardiovascular diseases. Targeting mitochondrial dysfunction has been an area of extensive research encompassing several approaches ranging from pharmacological agents to mitochondrial replacement techniques. Among them, mitochondrial transplantation has been a rapidly evolving approach, especially in the field of cardiovascular dysfunction for the restoration of injured or damaged myocardial cells. Various methods including tunneling nanotubes, nanoblade and “mitopunch” ensure the effective mitochondrial transfer from the donor to the recipient cell, with the internalization of the organelles, via endocytosis, enabling functional restoration. Results of preclinical and clinical trials involving mitochondrial transfer support the application of this technique in improving the function of the myocardium after damage caused by ischemia reperfusion injury. Herein, we discuss the beneficial role of mitochondrial transplantation in cardiovascular diseases and the current technical challenges of mitochondrial isolation, preservation, and targeted delivery, as well as their role in advancing precision medicine, offering a patient tailored therapeutic approach. Full article

The dynamic behavior within the melt pool governs the final quality of components fabricated by laser powder bed fusion (LPBF). To address key technical challenges—rapid keyhole evolution, low absorption contrast from metal vapor, and difficulties in quantifying internal flow fields—this study introduces move contrast X-ray imaging (MCXI), a technique leveraging time-series frequency characteristics. Combined with a multi-scale Horn–Schunck global optical flow method, MCXI enables full-field quantitative extraction of the melt-pool velocity field. Experimental validation across feature points shows a relative deviation of less than 2% compared to independent manual feature-point tracking, confirming consistency with the best available experimental ground truth. Analysis reveals the keyhole tail evolution cycle comprises three distinct dynamic stages: expansion, stratification, and contraction, with its area increasing from 1329 μm² to 6508 μm² before stabilizing. For the first time, pore pinch-off events were quantitatively measured, revealing front and rear wall collision velocities of 7.98 m/s and 8.04 m/s, respectively, consistent with available high-fidelity simulations. Furthermore, analysis of the overall melt-pool momentum field demonstrates a near-equal distribution of positive and negative momentum, providing an internal self-consistency check confirming the absence of systematic directional bias in the extracted velocity field. This study enables quantitative analysis of LPBF melt-pool dynamics, providing a novel tool for process optimization and defect control. Full article

To improve the visible-light-driven photocatalytic degradation efficiency of g-C₃N₄-based photocatalysts toward organic pollutants, a MoS₂/g-C₃N₄ composite precursor was employed in this work, and the phase composition and defect environment of Mo species were regulated by post-annealing under air and N₂ atmospheres, respectively, thereby constructing Mo-based/g-C₃N₄ (MCN) composites with distinct structural evolution characteristics. The results showed that the photocatalytic activity of the as-sonicated MCN composite toward methylene blue (MB) was only moderately improved, among which the 15% loading sample exhibited the best performance with a degradation efficiency of about 42.0% within 60 min. In contrast, annealing at 400 °C under N₂ resulted in only a slight activity change, whereas the sample treated at 400 °C in air (Air-15% MCN) achieved an MB degradation efficiency of 99.9% within 60 min, together with a much higher pseudo-first-order reaction rate constant than that of the air-treated sample at a lower temperature. XRD, FT-IR and XPS analyses revealed that air annealing induced the conversion of MoS₂ into highly crystalline MoO₃ (or MoO₃₋_x), leading to the formation of a reconstructed MoO₃₋_x/g-C₃N₄ composite interface. Meanwhile, the increased high-binding-energy component in the O 1s spectrum and the EPR signal around g ≈ 2.00 further suggested the presence of more abundant defect-related centers in the air-treated sample. Although Air-15% MCN possessed a lower specific surface area than the untreated and N₂-treated samples, it displayed enhanced visible-light absorption, higher transient photocurrent response, lower interfacial charge-transfer resistance, and accelerated carrier dynamics, indicating that the activity enhancement mainly originated from atmosphere-induced phase transformation, interfacial reconstruction, defect-related active centers, and improved charge separation/transfer, rather than from the surface area effect. Based on the above results, a possible interfacial charge-transfer pathway is tentatively proposed for the g-C₃N₄/MoO₃₋_x interface formed after air treatment, which contributes to the efficient utilization of photogenerated carriers and the rapid degradation of MB. This work demonstrates that atmosphere-induced phase transformation is a simple and effective strategy for regulating the structure and photocatalytic performance of Mo-based/g-C₃N₄ composites, and provides useful guidance for the design of efficient visible-light photocatalysts. Full article

Low charge-separation efficiency is a major factor limiting the photoelectric conversion performance of TiO₂. In this work, oxygen-vacancy-rich porous TiO₂ gel photocatalyst was successfully fabricated. The as-prepared material exhibits a three-dimensional interconnected hierarchical porous architecture with a specific surface area of 62.9 m² g⁻¹. EPR and XPS analyses confirmed the presence of Ti³⁺ defects and oxygen vacancies, which effectively increase the electron density and facilitate the separation and migration of photogenerated charge carriers. The results demonstrated excellent photocatalytic activity, with over 85% of RhB degraded within 50 min under light irradiation. In addition, its photocatalytic performance was further investigated by photocatalytic hydrogen evolution, and the hydrogen production rate reached 850.6 μmol·g⁻¹ h⁻¹. The enhanced photocatalytic performance can be mainly attributed to the synergistic effect of the hierarchical porous structure and oxygen vacancies. Specifically, the hierarchical porous structure improves mass transfer and provides abundant active sites, while oxygen vacancies modulate the electronic structure and promote charge separation, thereby significantly enhancing the catalytic activity. This work provides an effective strategy for improving the photoelectric conversion performance of TiO₂ and offers theoretical guidance as well as experimental support for the defect engineering and structural design of TiO₂-based photocatalytic materials. Full article

Abrasive waterjet machining (AWJM) is widely used for cutting aerospace aluminum alloys, but exit-side defects associated with jet lag can degrade surface integrity and dimensional accuracy. This work investigates the influence of water pressure, abrasive mass flow rate, and traverse feed rate on the formation of jet-lag defects at the exit side of cuts in UNS A92024 aluminum alloy plates of 10 mm thickness. A full factorial 3³ experimental design was implemented to manufacture 27 square samples (20 × 20 mm), which were subsequently characterized by optical microscopy at 20× magnification. The semicircular jet-lag defects were quantified using Imaging processing techniques to determine their projected area, and the resulting data were analyzed with multifactor ANOVA and multiple linear regression. The results show that traverse feed rate and water pressure have a statistically significant effect on defect area, with traverse feed rate being the most influential factor, whereas the abrasive mass flow rate plays a secondary role within the investigated range. Combinations of high water pressure and low traverse feed rate led to cleaner cuts with reduced exit-side damage, and contour plots allowed the identification of operational windows that minimize defect formation. The proposed methodology provides a systematic framework for characterizing jet-lag defects in AWJM and can be extended to other alloys, thicknesses, and advanced characterization techniques to support process optimization in industrial applications. Full article

Coated ferromagnetic conductors (CFCs) are widely used in the engineering field, such as transportation, petrochemicals, energy, etc. Owing to long-term exposure to harsh and corrosive environments, involving large temperature differences, cyclic loading and humidity, hidden corrosion occurring under the coatings of CFCs has been found to be one of the most critical defects posing a severe threat to the structural strength and safety of CFCs. Therefore, it is important to conduct rapid imaging and quantitative evaluation of this hidden corrosion via Non-Destructive Evaluation (NDE) techniques. A magnetic field-viewing film (MFVF) characterizes magnetic fields by displaying corresponding color shifts, offering a direct visual representation of the magnetic field intensity. In light of this, this paper proposes an MFVF-based probe composed of multiple micro-sensor units for fast imaging of hidden corrosion in CFCs. An image-processing technique based on the modified Canny algorithm is subsequently proposed for identification of corrosion opening profiles in MFVF images. Based on the identification results, an assessment of hidden corrosion parameters is conducted. It is inferred from the experimental results that the opening area, depth and volume of hidden corrosion can be quantitatively evaluated, with an average accuracy of 86.1%. Full article

Aero-engine defects often exhibit micro-scale and high-frequency characteristics under complex metallic textures, which makes precise segmentation difficult. Most existing pixel-level methods rely on spatial-domain modeling and lack frequency-domain decoupling. As a result, high-frequency details are easily hidden by low-frequency background information. In addition, repeated downsampling weakens the representation of fine-grained structures, leading to inaccurate boundary localization and limited robustness. To address these issues, a spectrum-driven hierarchical learning network is proposed for aero-engine defect segmentation. First, a dual-band spectral module is constructed using the discrete cosine transform to separate high-frequency and low-frequency components, providing stable and physically meaningful frequency-domain priors for the network. Second, a detail-guided module is designed where high-frequency features adaptively guide skip connections, compensating information loss during encoding and improving boundary recovery. Furthermore, a low-frequency-driven region-aware modeling module is developed. The internal defect regions, boundary areas, and background regions are modeled hierarchically. A dynamic hyper-kernel generation mechanism performs region-sensitive convolutional modeling, improving adaptation to complex structural variations. Extensive experiments on the Turbo19 and NEU-Seg datasets demonstrate that the proposed method produces accurate defect boundaries and achieves mIoU scores of 89.82% and 91.44%, improving over the second-best method by 5.22% and 4.42%, respectively. Full article

For power-grid applications such as transmission corridor inspection, substation asset inspection, and post-disaster emergency repair, reliable UAV self-localization under GNSS-degraded or GNSS-denied conditions is critical to ensuring operational safety and accurate defect geotagging. Due to substantial discrepancies in viewpoint, scale, and geometric structure between oblique UAV images and nadir satellite images, conventional RGB-based cross-view retrieval methods often suffer from unstable alignment and insufficient geometric modeling, particularly in scenarios with repetitive textures and partial overlap. To address these challenges, we propose a cross-view visual geo-localization model that integrates RGBD multimodal inputs with multi-scale attention enhancement. Specifically, MiDaS is used to estimate relative depth from UAV imagery, which is concatenated with RGB to form a four-channel input, while satellite images are padded with an additional zero channel to maintain dimensional consistency. A shared-weight ViTAdapter is adopted to learn joint semantic–geometric representations, and a lightweight Efficient Multi-scale Attention (EMA) module is adopted on spatial feature maps to strengthen multi-scale spatial consistency. In addition, an IoU-weighted InfoNCE loss is employed to accommodate partial matching during training, thereby improving the robustness of feature alignment. Experiments on the GTA-UAV dataset under the cross-area protocol show stable performance across both retrieval and localization metrics. Specifically, Recall@1, Recall@5, and Recall@10 reach 18.12%, 38.83%, and 49.47%, respectively; AP is 28.01 and SDM@3 is 0.53; meanwhile, the top-1 geodesic distance error Dis@1 is 1052.73 m. These results indicate that explicit geometric priors combined with multi-scale spatial enhancement can effectively improve cross-view feature alignment, leading to enhanced robustness and accuracy for localization in challenging power inspection scenarios. Full article

Peripheral nerve injuries involving critical-sized gaps remain a major clinical challenge. Although autologous nerve grafting is considered the gold standard for peripheral nerve repair, its clinical application is limited by the availability of donor nerve tissue and the risk of donor-site morbidity, including sensory deficits and functional impairment. Therefore, nerve guidance conduits (NGCs) have emerged as a promising alternative when combined with bioactive modulation strategies. In this study, we evaluated bisvinyl sulfonemethyl (BVSM)-crosslinked gelatin conduits integrated with electrical stimulation (ES) at different frequencies (0, 2, 20, and 200 Hz) in a rat sciatic nerve defect model over a 4-week recovery period (n = 10 per group). Structural regeneration was assessed by morphometric analysis, electrophysiology, macrophage infiltration, CGRP immunoreactivity, retrograde Fluorogold tracing, quantitative PCR of growth factors and inflammatory cytokines, and behavioral testing. Among all stimulation paradigms, low-frequency ES at 2 Hz produced the most pronounced regenerative effects. The 2 Hz group demonstrated significantly greater axon number, axonal density, and regenerated nerve area compared with control and high-frequency groups (p < 0.05). Electrophysiological assessments revealed improved nerve conduction velocity, higher MAP amplitudes, and shorter latencies. Enhanced macrophage recruitment and elevated CGRP expression were observed, suggesting coordinated neuroimmune and neurochemical activation. Gene expression analysis indicated upregulation of neurotrophic factors and balanced inflammatory cytokine responses under low-frequency stimulation. In contrast, high-frequency stimulation (200 Hz) failed to enhance overall regeneration and showed reduced axonal metrics, suggesting possible overstimulation-associated suppression. Collectively, these findings demonstrate that BVSM-crosslinked conduits provide a stable and biocompatible regenerative scaffold, and that appropriately tuned low-frequency electrical stimulation (2 Hz) optimally enhances structural, molecular, and functional recovery. The integration of material engineering with bioelectrical modulation represents a promising strategy for next-generation bioelectronic interfaces in peripheral nerve repair. Full article

The residual sub-millimeter metal particles in gas-insulated metal enclosed switchgear (GIS) and gas-insulated transmission lines (GILs) are significant factors that trigger insulation failures. During actual operation, these particles not only endure the action of alternating electric fields but also are continuously stimulated by mechanical vibrations. Current research mostly focuses on the behavior of millimeter-sized particles under a single physical field, lacking in-depth understanding of the jumping characteristics of sub-millimeter-scale particles under the combined action of alternating electric fields and mechanical vibrations. This paper has built a collaborative action test platform and constructed a spherical-bowl-shaped electrode defect model. It systematically studied the jumping behavior, motion evolution, and local discharge characteristics of 20-mesh and 40-mesh irregular aluminum particles under the combined action of different voltages (0–7 kV) and mechanical vibrations (amplitude 0.01–0.1 mm, frequency 10–100 Hz). The results show that mechanical vibrations provide initial kinetic energy for the particles, significantly reducing the threshold for jumping, and are the key initiating factor in the collaborative action; in the low-voltage stage, vibration dominates the jumping behavior, while in the high-voltage stage, the electric field dominates the motion evolution; and under dual stimulation, the jumping area of the particles is wider and the motion forms are more diverse (such as flying-flying motion, vertical state, pile-up excitation, etc.), and the starting voltage of discharge is significantly reduced, the discharge repetition rate increases with the increase in vibration intensity and voltage, and is closely related to the particle size. This paper reveals the uniqueness of particle motion and discharge under the collaborative action, providing a theoretical basis for the assessment of multi-physical field states and fault prediction of GIS/GIL. Full article

Indium oxide was mechanically activated, and its effect on the operation of semiconductor gas-sensitive devices was evaluated. The structural and morphological characteristics of In₂O₃ following mechanical activation were examined. The powder treatment produced a defective particle surface structure, enhanced specific surface area, and improved material diffusion properties. Experimental evidence indicates a substantial enhancement in the reactivity of indium oxide with diverse gases, stemming from alterations in grain structure and the formation of novel adsorption sites. The results obtained demonstrate that mechanoactivation is a promising technological tool for the development of energy-efficient sensors. Full article

Ti alloys are widely used in aerospace and biomedical fields due to their high mechanical properties under severe loading. Interest in additively manufactured Ti6Al4V has increased, but further research is needed to fully characterize their properties. This work compares the effects of surface properties, internal defects, microstructure, hardness, and Hot Isostatic Pressing (HIP) or Vacuum Heat Treatment (VHT) on the fatigue behavior of Ti6Al4V produced by Selective Laser Melting (SLM) and Electron Beam Melting (EBM). Printing parameters and post-processing were optimized to achieve high density and minimal porosity, providing a solid basis for realistic fatigue comparisons. Samples were characterized in terms of microstructure (optical microscopy and SEM), mechanical properties (hardness mapping), surface texture (confocal microscopy), and internal defects (image-based analysis). Uniaxial fatigue limits were determined by a Dixon-Mood staircase method, and failed specimens were analyzed for fracture surfaces and defect areas. Applied load on flaws was evaluated to identify root causes of fatigue failure. Results showed that fatigue of as-printed samples is governed by surface roughness, while machined specimens are controlled by internal defect size. Machining increased the fatigue limit roughly threefold, and HIP further improved it by 10–20% by reducing internal porosity. In conclusion, with properly optimized melting parameters, both EBM and SLM produce similar mechanical performance at comparable roughness, supporting their use for structural components. Full article

This study conducts multi-scale numerical simulations spanning atomic to macroscopic scales (i.e., from nanometer to millimeter scale) to investigate the fatigue crack propagation behavior in the welded heat-affected zone (HAZ) of AH36 shipbuilding steel. A coupled molecular dynamics–finite element method (MD-FEM) was employed to establish a multi-scale model. Through the transfer of boundary displacements, equivalent mapping of crack morphology, and crack-tip tracking, an iterative multi-scale simulation of 600 tension–tension fatigue cycles was achieved. The results indicate that the crack propagation rate is significantly influenced by crack tip morphology (blunting/sharpening) and growth direction. Notably, the peak strain at the boundary is not the sole determining factor. Periodic blunting of the crack tip occurs during cyclic loading, accompanied by a decrease in the propagation rate. Additionally, the stress field near the crack tip induces microscopic defects such as voids in the nearby area, affecting the crack propagation. This study, based on multi-scale analysis, reveals the microscopic mechanism and evolution law of fatigue crack propagation in the heat-affected zone of AH36 steel welds. Full article