Search Results (16,952)

Accurate weld keypoint localization is an important visual perception task for robotic welding, weld tracking, and intelligent manufacturing. However, weld keypoints in line-structured light images are usually small, weakly textured, and easily affected by reflections, noise, and spurious laser stripes. These factors make it difficult for lightweight detection models to balance localization accuracy and computational efficiency. To address this problem, this paper proposes Weld-FHG-YOLO, a lightweight multi-frequency feature fusion network for weld keypoint localization. The proposed model is built on the You Only Look Once version 11 nano (YOLO11n) framework and focuses on optimizing feature fusion and scale transformation in the Neck. Specifically, FasterC3K2 is introduced to replace the original C3K2 modules in the Neck, thereby reducing redundant computation during multi-scale feature fusion. In addition, a Haar Wavelet Decomposition and Group Shuffle Convolution (HWD-GSConv) downsampling fusion module is designed, in which Haar wavelet decomposition preserves low-frequency structural information and high-frequency details, while GSConv performs lightweight multi-frequency feature fusion. Experimental results show that Weld-FHG-YOLO achieves 2.301 M parameters and 6.016 GFLOPs, which are 11.26% and 6.83% lower than those of YOLO11n, respectively. Meanwhile, mAP@0.5:0.95 increases from 0.7337 to 0.7901, the Mean Center Error (MCE) decreases from 2.254 px to 2.131 px, and the CPU inference speed increases from 13.69 to 14.77 frames per second (FPS). These results indicate that the proposed method improves strict localization accuracy and localization stability while maintaining a lightweight computational profile, providing a practical visual perception approach for weld keypoint localization in resource-constrained intelligent manufacturing scenarios. Full article

High-entropy alloys (HEAs) and multi-principal-element alloys (MPEAs) provide broad compositional flexibility for regulating phase stability, microstructure, and properties. However, nominal composition and average phase constitution alone are insufficient to describe the actual material state formed during processing and service. This review summarizes the thermodynamic and diffusion-kinetic basis of phase formation and compares five representative fabrication routes, including mechanical alloying, vacuum melting, severe plastic deformation, magnetron sputtering, and additive manufacturing. Particular attention is given to the effects of processing history on grain structure, texture, elemental segregation, defects, phase constitution, and local chemical order. Computational methods and multiscale characterization techniques are also discussed in relation to the identification and interpretation of processing-dependent material states. Current studies indicate that alloys with identical nominal compositions can exhibit different microstructures and properties because of differences in thermal history, strain path, elemental redistribution, defect populations, and post-processing conditions. The review further examines strength and ductility, corrosion resistance, oxidation resistance, irradiation tolerance, and catalytic performance, with emphasis on the evolution of microstructure and surface state under service conditions. These results indicate that reliable evaluation of HEAs and MPEAs requires consideration of processing reproducibility, structural heterogeneity, and long-term stability rather than isolated peak properties. This processing–structure–service perspective provides a basis for more reliable comparison, selection, and engineering assessment of HEAs and MPEAs under application-relevant conditions. Future research should focus on reproducible fabrication, integration of computational prediction with experimental validation, multiscale assessment of structural evolution, long-term service performance, scalable processing, and sustainable alloy design. Full article

Titanium alloy bone scaffolds have been widely used in the clinical treatment of bone defects. However, conventional titanium alloy bone scaffolds exhibit a lack of porous structure and excessively high elastic modulus, resulting in poor osseointegration. In this study, mimicking the structural characteristics of human bone—namely dense exterior and porous interior—three types of bionic Gyroid titanium alloy bone scaffolds with a uniform porosity of 50% but distinct gradient properties were designed, including uniform lattice structure, linear gradient structure, and quadratic gradient structure. Process optimization of selective laser melting (SLM) and characterization of the as-fabricated microstructures were carried out. The tensile and compressive properties of additively manufactured titanium alloy bone scaffolds were investigated via mechanical testing and finite element analysis (FEA). The results demonstrate that optimized SLM parameters yield a matrix relative density of 98.56% for solid Ti-6Al-4V reference specimens. Using these parameters, bionic gradient-porosity Gyroid bone scaffolds were successfully manufactured. The bionic quadratic function gradient design achieves optimal modulus matching (10–30 GPa) and sufficient mechanical strength at the design level, satisfying the mechanical requirements for bone scaffolds and showing favorable application potential for load-bearing bone scaffolds. Full article

Liver-targeted drug delivery offers opportunities to increase therapeutic exposure at sites of hepatic disease while limiting systemic toxicity; however, successful targeting requires more than preferential accumulation of a carrier within the liver. This narrative review critically summarizes recent advances in synthetic, biological, and biomimetic delivery platforms, including lipid, polymeric, inorganic, and protein-based nanoparticles, nucleic acid nanocarriers, extracellular vesicles, plant-derived nanovesicles, cell-mediated systems, and cell membrane-coated nanoparticles. A literature search was conducted using PubMed, Web of Science, and Embase, with emphasis on studies published during the last decade and updated through 24 August 2026. Particular attention is given to the biological determinants of hepatic biodistribution, including sinusoidal architecture, physicochemical carrier properties, protein corona formation, receptor–ligand interactions, and disease-associated alterations in the hepatic microenvironment. The review distinguishes organ-level hepatic accumulation from cell-specific uptake and productive intracellular delivery and discusses strategies directed toward hepatocytes, hepatic stellate cells, Kupffer cells and other macrophages, liver sinusoidal endothelial cells, neutrophils, and additional immune-cell populations. Major delivery platforms are critically compared with respect to the evidence supporting targeting specificity, cargo compatibility, administration route, reported safety and immunogenicity, manufacturability, analytical characterization, and translational maturity. Particular consideration is given to extracellular vesicle- and plant-derived nanovesicle-based approaches, for which biological activity, biodistribution, standardization, and scalability remain important areas of investigation. Overall, current research in liver-targeted delivery is increasingly focused on moving beyond nonspecific organ accumulation toward disease-adapted, cell-specific, and intracellularly productive delivery, although substantial biological, manufacturing, and regulatory challenges remain before many emerging approaches can achieve routine clinical translation. Full article

We investigated the possibility of developing super austenitic stainless steel Avesta SMO 254 X1NiCrMoCuN20-18-7 (EN 10088-4) and austenitic stainless steel X15CrNiSi25-21 (EN 10095) coated with SiC, resulting in the obtainment of a Metal Matrix Composite (MMC) by additive manufacturing (AM) for the upgrade of nozzles for sulfur recovery thermal reactors. One layer of the MMC targets the outer surface of the part that is in constant contact with the flame and the area is subjected to high friction erosion. The Directed Energy Deposition Laser (DED-LB) method has made it possible to produce a high strength-to-weight ratio. The aim is to engage lower-cost material with similar thermal stability and durability in extreme conditions. The robotic unit used for the application allowed for computer control of the positioning, feeding of the SiC particles inside the shielding gas and deposition in the molten pool. After the solidification process, visual testing (VT) and ultrasonic testing (UT) were applied for non-destructive evaluation, checking for disbonding and subsurface imperfections. Then, samples were tested with microhardness measurements, bond strength, microcracking detection, porosity, interface zone assessments and microstructural analysis. The process achieved 0.4 to 0.7 KJ mm⁻¹ heat input with no defects and the intended nozzle surface passed UT and VT. Controlled parameters provided strong metallurgical bonding. Full article

This study systematically investigates the effects of infiltration temperature (800 and 1000 °C) and magnesium (Mg) content (0, 5, and 10 wt.%) on the density, morphology, and chemical composition of silicon carbide/aluminum-magnesium (SiC/Al–Mg) composites. Poor wettability between molten Al and SiC can restrict the infiltration of porous SiC preforms. Although Mg is commonly used to improve wettability, the combined effects of Mg content and infiltration temperature have not been investigated for composites produced from binder-jetted SiC preforms. Porous SiC preforms were first fabricated by binder jetting of SiC powder and then air-assisted oxidation bonded at 1200 °C for 2 h. The oxidation-bonded preforms were subsequently spontaneously melt infiltrated under an inert atmosphere using either pure Al powder or Al–Mg powder mixtures containing 5 or 10 wt.% Mg. The results showed that composite density increased consistently with increasing Mg content. At 800 °C, the density increased from 1.73 to 2.63 g/cm³ as Mg content increased from 0 to 10 wt.%. Similarly, at 1000 °C, the density increased from 1.80 to 2.73 g/cm³. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to evaluate phase formation and microstructural features. The results confirmed effective infiltration in Mg-containing samples, while samples without Mg showed limited infiltration at both temperatures. A two-way ANOVA showed that Mg content was the primary factor controlling post-infiltration density, while infiltration temperature had a smaller but statistically significant effect. These findings provide practical guidance for selecting Mg content and infiltration temperature during the fabrication of binder-jetted SiC/Al–Mg composites. Overall, this study highlights the importance of Mg-assisted infiltration for fabricating binder-jetted SiC/Al–Mg composites and provides processing insights relevant to their potential use in aerospace, automotive, and defense applications, subject to further evaluation of their mechanical and functional properties. Full article

The development of 4D-printing technology enables the fabrication of smart structures capable of transforming in response to external stimuli, offering potential for future minimally invasive biomedical applications. This study explores a direct 4D-printing approach for producing thermally actuated polylactic acid (PLA) components, focusing on self-expanding vascular stent prototypes. Unlike conventional 4D printing, which typically requires a separate post-printing programming step (e.g., heating, mechanical loading, cooling, and unloading), direct 4D printing embeds the programming phase directly into the layer-wise printing process by controlling the adjustment of process parameters, so that components are ready for shape transformation immediately after fabrication. A systematic experimental workflow was applied by combining a problem-solving methodology with action research and structured experimentation to identify and optimize the key parameters governing shape-shifting behavior. Bilayer plate structures were fabricated via fused filament fabrication (FFF) using multiple PLA material combinations and were thermally actuated under controlled conditions to characterize the influence of printing speed, printing temperature, and infill pattern on the magnitude and directionality of deformation. Building on these results, three functional demonstrators were developed, culminating in a grid-based cylindrical prototype that achieved approximately 5.8% radial expansion upon actuation at temperatures above 80 °C. Overall, the results suggest the fundamental technological feasibility of direct 4D printing as a manufacturing route for thermally actuated components, serving as a foundational proof-of-concept for future patient-specific, self-deploying medical devices. Full article

Transformer lifecycle data across organizations are typically vertically partitioned among material suppliers, manufacturers, logistics service providers, testing agencies, and operation and maintenance units. This study presents a reproducible multi-layer vertical federated learning (VFL) prototype that integrates salted-hash identifier matching, additive sharing of local score vectors over finite fields, and a local public key infrastructure with a signature-based audit verification mechanism. A deterministic synthetic dataset is first constructed, comprising 5200 aligned records and 31 predictor variables, which are partitioned among five participants with varying numbers of features per participant. Second, across five validation runs, the VFL models under both the standard block-wise and score-sharing paths achieved an AUC of 0.8825 ± 0.0119, an F1 score of 0.7367 ± 0.0249, and an accuracy of 0.8102 ± 0.0183 on the test set. The classification results of both paths were fully consistent with the centralized gradient-descent logistic regression baseline. Notably, the score-sharing path exhibited a maximum log-odds deviation of only 2.22 × 10⁻⁸ on the test set, with no prediction discrepancies observed. Third, across 10 independently generated synthetic populations, the nonlinear output mechanism highlights the limitations of linear models: the AUC of vertical federated learning (VFL) drops to 0.6457 ± 0.0171, while Extra Trees and HistGradientBoosting achieve 0.7731 ± 0.0149 and 0.7743 ± 0.0139, respectively. Finally, in a separate residual-sharing diagnostic test, when 1 to 4 participants jointly shared the residuals, the label inference AUC remained around 0.499–0.500; however, when all five participants shared or plaintext residuals were used, the labels could be fully recovered. Both simple membership inference diagnostic tests yielded results close to random. The local signature log verifier rejected all 700 injected faults and accepted the 400 clean control log events. These results validate the feasibility of numerical reproducibility and local audit functionality under synthetic data and single-process conditions, yet they are insufficient to demonstrate end-to-end label privacy protection, malicious security, effectiveness on real data, or real-time ledger performance. Full article

Auxetic mechanical metamaterials convert axial compression into lateral contraction, providing deformation modes that are attractive for lightweight energy absorbers. Here, fused deposition modeling was used to fabricate polylactic acid (PLA) and 10 wt% short-carbon-fiber-reinforced PLA (CF/PLA) auxetic metamaterials with arrow, re-entrant hexagonal, star-shaped, and chiral rotating topologies. Thermal analysis, tensile testing, and three-point bending first established the effect of carbon-fiber addition on the printable matrix. Quasi-static compression experiments were then combined with finite-element simulations using pressure-dependent plasticity and ductile damage to resolve topology-dependent collapse and energy partition. Adding 10 wt% short carbon fibers increased the tensile modulus from 2.33 to 3.72 GPa and raised the plateau stresses of the auxetic structures by about 50%. The star-shaped CF/PLA metamaterial showed the highest specific energy absorption (approximately 4.7 J/g), whereas the chiral rotating topology showed the largest relative improvement, exceeding 130%. Fiber reinforcement improved stiffness and load transfer but promoted stress localization at hinges, re-entrant corners, and ligament junctions. These findings elucidate the material–topology trade-off between stiffness enhancement and localized embrittlement, offering practical guidelines for designing crashworthy 3D-printed composite metamaterials. Full article

Emerging composite materials are expanding the potential of additive manufacturing and enabling applications previously restricted by traditional manufacturing methods through their multi-phase nature and complex internal geometry. Additionally, these materials can be pyrolyzed to create dense metal, ceramic, and glass parts with geometries typically not achievable by traditional processes. Additive manufacturing of borosilicate glass composites can enable new applications in nuclear engineering, astronomy, and bone regrowth therapy. To elucidate the process–parameter relationship of borosilicate–polylactic acid (PLA) composites, mechanical test specimens were fabricated by fused-filament fabrication and compared with a pure PLA baseline. Optical and scanning electron microscopy were conducted to observe the specimen microstructure before and after testing. From the stress–strain curves, the highest compressive yield strength for the composite was 28.22 MPa, and the highest compressive yield strength for PLA was 49.30 MPa. Print orientation was found to benefit the composite material but have a detrimental effect on the pure matrix material. Borosilicate–PLA with 100% infill, 1 shell wall, and layer lines parallel to compression axis had an elastic modulus of 2.66 GPa. Microscopy revealed that lower-modulus composite specimens had the particulates re-distributed within the matrix. Tensile testing was done according to a polymer testing standard, which caused difficulties obtaining consistent fracture within the gauge length. Full article

Polyethylene, the most widely used and inexpensive commodity thermoplastic, remains unsuitable for 3D printing via fused deposition modeling (FDM) because of shrinkage-induced warping. Herein, this study aimed to develop a single-step reactive extrusion process to improve the filament-forming ability and 3D printability of high-density polyethylene (HDPE). HDPE was reacted with maleic anhydride, 1,10-decanediol, and a zinc acetate catalyst via peroxide-driven grafting in a melt extruder, and the subsequent coupling reactions yielded ester-containing, modified polyethylene structures. Unlike unmodified HDPE, which produced irregular filaments and poor 3D printing, the modified HDPE formulations produced filaments with a consistent diameter and enabled successful FDM printing with improved print quality. The optimized carbon-black-containing modified HDPE systems exhibited substantial mechanical improvements, with average enhancements of approximately 50–75% in tensile stress at break and an approximately 200% increase in elongation at break compared with neat HDPE. These results demonstrate that ester-containing HDPE has the potential to convert commodity HDPE into a melt-processable and mechanically improved feedstock for additive manufacturing applications. This study suggests that widely available post-consumer pigmented HDPE, which is otherwise unsuitable for reuse in packaging, could potentially be explored for 3D printing as an alternative to expensive acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA). Full article

A polyurethane coating represents the conventional solution for protecting and finishing visible wooden furniture surfaces. However, the increasing use of additive manufacturing has introduced visible 3D-printed polymer components whose surface mechanical performance is relevant to their application in furniture. This study investigated the effect of short-term exposure to 60 °C for 1 h on the surface mechanical properties of a pigmented polyurethane coating applied to oak wood and 3D-printed PLA, ABS-T and PET-G components. Specimens were evaluated under laboratory conditions (20 °C) and immediately after exposure to 60 °C, while their surfaces remained at an elevated temperature. Impact resistance, abrasion resistance, and scratch resistance using a tungsten carbide tip were determined according to the relevant standards, and the surface damage was assessed by visual inspection and digital microscopy. The polyurethane coating exhibited the smallest impact indentation diameter but showed earlier crack initiation and lower abrasion resistance than the 3D-printed polymers. Among the investigated polymers, ABS-T provided the most balanced combination of impact resistance, abrasion resistance and surface hardness, whereas PLA exhibited the greatest dimensional changes after exposure to 60 °C. Microscopic analysis revealed surface defects that were not detectable by visual inspection, demonstrating the value of digital microscopy for detecting subtle surface damage. The results indicate that ABS-T is a promising material for visible furniture components exposed to short-term elevated temperatures, while PET-G should be used with caution in applications exposed to radiant heat or direct sunlight. Full article

Bacterial infection, biofilm formation, and the associated oxidative stress and persistent inflammation represent major obstacles to wound healing, tissue engineering, and implantable medical devices. Owing to their highly hydrated three-dimensional networks, favorable tissue compatibility, and versatile capacity for functional loading, hydrogels have been widely investigated for the treatment of infected wounds. This review systematically summarizes the major antibacterial mechanisms of hydrogels, including cationic contact-killing, chemical antibacterial activity mediated by metal ions and reactive halogen species, nanozyme-catalyzed reactions and bidirectional regulation of reactive oxygen species, as well as photothermal synergistic antibacterial therapy. Key design strategies are also discussed, including natural polymer-based matrices, multiple dynamic crosslinking, stimuli-responsive controlled release, three-dimensional printing, and spatial compartmentalization. In addition, recent advances in infection-microenvironment regulation, wet-interface adaptation, temporally coordinated tissue repair, and integrated diagnosis and therapy are highlighted. The field is currently shifting from single-mode bacterial eradication toward multistage tissue repair and intelligent theranostics. However, major challenges remain, including balancing antibacterial efficacy with biosafety, achieving reproducible manufacturing and sterilization-compatible formulations, maintaining functional stability during storage, and improving the clinical relevance and standardization of preclinical evaluation. In addition, most smart systems still lack quantitative coupling among pathological signals, therapeutic dosage, and treatment outcomes. Future studies should therefore integrate mechanistic design with manufacturing reproducibility, clinically relevant validation, and quantitative feedback regulation, thereby advancing antibacterial hydrogels from multifunctional proof-of-concept systems toward precise, controllable, and clinically translatable therapeutic platforms. Full article

Three-dimensional (3D) printing technology has become more and more popular in restorative dentistry; however, information regarding the mechanical properties of 3D-printed restorative materials remains limited. The aim of this study was to evaluate the behavior under compressive loading until fracture of occlusal veneers fabricated from two types of 3D-printed resin composites, Saremco Print Crowntec A2 and Voco V-Print C&B Temp A2, intended for permanent and temporary clinical restorations, respectively. The study design involved scanning a first upper premolar typodont tooth, previously prepared to receive an occlusal veneer restoration, followed by the computer-aided design of the occlusal veneers and resin dies and 3D printing, resulting in 20 samples. The cemented restorations were subjected to mechanical testing using a fracture-resistance test at a speed of 5 mm/min, applied until failure. The recorded failure forces ranged between 571 and 970 Newton (N), values that are comparable to physiological masticatory forces. The absorbed energy was calculated as the area under the force–displacement curve using the trapezoidal integration method. The mean energy at failure was 0.301 Joule (J) (Voco) and 0.244 Joule (J) (Saremco), with Voco demonstrating greater toughness. In terms of fracture pattern classification, the 3D-printed resin with a lower filler content presented a more catastrophic failure mode compared with the material with a higher filler content. Fractographic analysis revealed characteristic fracture patterns and failure-specific features. Higher predictability and greater fracture strength were observed for the low-filled material, as indicated by the Weibull analysis. Full article

The performance of Peltier-driven atmospheric water generation (AWG) systems depends strongly on the surface geometry and wetting behavior of the condensation structure. Triply periodic minimal surfaces (TPMS) provide high surface area-to-volume ratio and geometric tunability, but their effectiveness as three-dimensional condensation structures requires experimental evaluation. In this study, five additively manufactured TPMS geometries, Gyroid, Diamond, Lidinoid, SplitP, and Schwarz, were evaluated in a Peltier-driven AWG setup under controlled laboratory conditions. The measured water collection response varied among the tested TPMS geometries, which showed different condensation, retention, and collection trends. Water collection was measured with and without surface treatment, while the monitored surface temperature remained below the calculated dew point during testing. Without surface treatment, total water collection ranged from approximately 0.9 to 1.4 g, whereas surface-treated specimens collected approximately 0.6 to 1.2 g. The specimens with surface treatment exhibited predominantly discrete droplets rather than the film-wise morphology observed without surface treatment, but the total water collection did not increase consistently. Gyroid and Lidinoid showed slight increases with surface treatment, while SplitP, Diamond, and Schwarz showed reductions. Water collection also did not scale directly with calculated TPMS surface area, which suggests that effective air exposure, droplet retention, drainage, and coating uniformity contributed strongly to the observed performance. These findings provide experimental insights into additively manufactured TPMS geometry and surface treatment conditions for Peltier-driven AWG. Full article