Search Results (572)

The growing volume of industrial waste and the need for sustainable material solutions drive the search for cost-effective fillers and energy-efficient processing methods for polymer composites. This study investigates the valorization of brick dust (BD), a fine ceramic waste, as a reinforcing filler for unsaturated polyester resin (UPR), combined with microwave (MW) treatment applied at different stages of composite fabrication. The brick dust was comprehensively characterized using laser diffraction, SEM, EDX, XRD, and FTIR, revealing an environmentally safe aluminosilicate powder with a mean particle size of 3–6 µm, plate-like morphology, and surface hydroxyl groups favorable for matrix interaction. The optimal filler content was found to be 50 phr, which increased flexural strength by 6.5%, flexural modulus by 134%, tensile strength by 11%, and impact strength by 40% compared to neat UPR. Among the MW strategies evaluated, post-curing of the fully polymerized composite for 120 s proved most effective, yielding further improvements in flexural strength (110 MPa, +34.1%), flexural modulus (8250 MPa, +49.7%), impact strength (13.8 kJ/m², +119%), and Shore D hardness (88). MW post-curing also increased the gel fraction from 95.0% to 97.8%, raised the thermal stability index (THRI) from 150.6 to 165.8, and reduced equilibrium water absorption from 0.62% to 0.47% with a reversibility index of 87.5%. Fracture surface analysis confirmed a transition from interfacial debonding to cohesive matrix failure, with ultra-thin polymeric veils replicating the scaly filler structure. These results demonstrate that microwave post-curing synergistically enhances the mechanical, thermal, and moisture-resistant properties of brick dust-filled polyester composites. Full article

Additive manufacturing using laser powder bed fusion (LPBF) has been widely used to produce nickel-based superalloy components with complex shapes for high-temperature applications requiring creep resistance. In this research, the creep behavior of LPBF Inconel 718 under solution and double-aging heat treatments, performed at 590–650 °C under stresses of 450–550 MPa, is studied. The characterization included optical microscopy, scanning electron microscopy (SEM), porosity analysis, Vickers microhardness tests, and fracture surface examination. The findings revealed that even after heat treatment, the material maintained a mainly directional, columnar microstructure, with an average porosity below 1%, which was unevenly distributed and contained critical defects related to lack-of-fusion (LOF) and trapped powder. Fracture after creep presents regions of ductile failure alongside facets indicative of quasi-cleavage. Kinetic analysis revealed a high stress exponent (n = 18.26) and an activation energy (Qc = 410–538 kJ/mol), indicating that the deformation operates within the power-law breakdown (PLB) regime, where dislocation–precipitate interactions govern the creep rate in this precipitation-strengthened superalloy. Overall, the results highlight that the directional microstructure and residual defects typical of LPBF can reduce the creep resistance of Inconel 718, underscoring the importance of post-processing methods and internal defect control specifically tailored for additively manufactured materials. Full article

Magnetic skyrmions have emerged as promising candidates for next-generation nanomagnetic devices owing to their stability, nanoscale size, and efficient manipulability. In this work, we demonstrate the deterministic creation of skyrmions using a single ultrafast laser pulse in a thin ferromagnetic film. Through micromagnetic simulations, we model the effect of a focused picosecond laser pulse on a Pt/Co-based multilayer with interfacial Dzyaloshinskii–Moriya interaction (DMI). We find that above a threshold laser fluence, or equivalently, a critical pulse duration, a stable 25 nm Néel-type skyrmion diameter is created at low temperature under a modest out-of-plane magnetic field. Our results demonstrate that skyrmions can be written deterministically by a single picosecond laser pulse, eliminating the need for multiple exposures or electrical stimuli. This work systematically identifies the ultrafast excitation and material-parameter ranges that enable stable solitary skyrmion nucleation in experimentally realistic magnetic multilayers. This can be a foundation for photonic-spintronic integration, enabling optical data writing and magnetic storage, offering a pathway toward ultrafast, energy-efficient, and contactless control of topological spin states for future memory and logic applications. Full article

Energy consumption and resource utilization have become critical challenges in modern machining due to increasing manufacturing costs, stringent environmental regulations, and global carbon-reduction targets. While sustainable machining strategies such as dry machining, minimum quantity lubrication (MQL), and cryogenic cooling have been widely investigated, recent years have witnessed the rapid development of advanced assisted and hybrid machining processes aimed at further reducing energy demand and material waste. However, existing review studies largely focus on individual techniques or lubrication approaches, lacking a systematic perspective on the combined energy–resource saving mechanisms in advanced sustainable machining. This review presents a comprehensive and up-to-date analysis of energy consumption characteristics and resource-saving strategies in advanced sustainable machining processes. Particular attention is given to emerging and hybrid technologies, including ultrasonic-assisted machining, ultrasonic-assisted MQL, electrostatic MQL (eMQL), multi-nozzle MQL systems, nanofluid-based MQL, laser-assisted machining, vortex tube-assisted cooling, dry ice machining, and hybrid cryogenic–MQL strategies such as LN₂-MQL and CO₂-MQL. The review systematically discusses how these techniques influence energy flow, tool–workpiece interactions, lubrication efficiency, and thermal behavior during machining. Furthermore, this paper highlights the synergistic effects of combining multiple assistance methods, emphasizing their role in achieving simultaneous improvements in productivity, tool life, surface integrity, and sustainability performance. Energy-based metrics, resource efficiency indicators, and carbon emission considerations reported in the literature are critically evaluated to identify current limitations and inconsistencies. Finally, key research gaps and future directions are outlined, including the need for standardized sustainability assessment frameworks, data-driven energy optimization, and intelligent hybrid machining systems. This review aims to provide a valuable reference for researchers and practitioners seeking to design next-generation sustainable machining processes with enhanced energy efficiency and reduced environmental impact. Full article

Methacrylate-based materials, widely used in dentistry, must possess high biocompatibility with oral cells and tissues. Currently, to improve the integration of orthodontic devices with the biological structures, laser-assisted polymer modification is actively employed. Importantly, functionalization is required only for the surface of the material that directly interacts with the oral tissues. This study presents approaches for laser modification of polymethacrylate materials and evaluates their influence on the proliferative activity of human spleen fibroblasts. Using laser radiation, two geometric patterns were obtained on the polymer surfaces. Cell morphology and proliferation on the experimental samples were assessed using scanning electron microscopy. It was found that the polymer with a groove-textured surface (pattern 1) promoted enhanced cell adhesion and reduced material toxicity. Additionally, the antibacterial properties of the polymers were evaluated. The sample with sparsely distributed surface craters (pattern 2) demonstrated an antifouling effect against Escherichia coli. Full article

Laser-induced breakdown spectroscopy (LIBS) offers rapid, in situ, and multi-element detection, and therefore shows strong potential for quality monitoring of metal powders in additive manufacturing. However, direct LIBS analysis of flowing metal powders is often affected by particle splashing, unstable laser–particle coupling, and plasma fluctuations, which reduce signal repeatability and detection reliability. To address these issues, this study developed an integrated measurement and classification framework for identifying cross-contamination in additive-manufacturing metal powders. A stable powder particle stream was generated through vibratory feeding and particle-flow focusing, while a hollow quartz tube with a side opening was introduced to provide cylindrical spatial confinement, thereby improving the stability of laser–particle interaction and enabling in situ spectral acquisition without pellet preparation. TC4 powder was used as the base material and AlSi10Mg powder as the contaminant, and samples with contamination levels of 0, 0.5, 1, 2, and 5 wt.% were prepared. Two independent batches of single-shot LIBS spectra were collected. To reduce the influence of strong spectral fluctuations, outlier spectra were removed using full-spectrum total-intensity quantile filtering, followed by asymmetric least-squares baseline correction and standard normal variate transformation. PCA combined with multiple machine-learning models was then applied for contamination identification. The results showed that LIBS spectra at different contamination levels exhibited distinguishable distributions in principal-component space, and the spectral differences between clean and contaminated powders became more pronounced with increasing contamination level. In binary classification, several models achieved high classification accuracy at medium and high contamination levels, while PCA-SVM-RBF showed the best performance at low concentrations. In five-class cross-validation, the 5 wt.% class exhibited the clearest decision boundary, whereas confusion remained among low and adjacent contamination levels, indicating that contamination-induced spectral responses followed a more continuous transition. These results demonstrate that the proposed spatially confined particle-flow LIBS framework combined with machine-learning classification can effectively achieve rapid identification of cross-contamination in additive-manufacturing metal powders and provides a feasible technical route for online powder quality monitoring. Full article

The photothermal conversion capability of polydopamine (PDA) was exploited to load the anticancer drug doxorubicin (DOX) onto its surface via π-π stacking and hydrogen-bond interactions, yielding a PDA-DOX complex. In this study, biocompatible poly-L-lactic acid (PLLA) was employed as a shell material to fabricate multifunctional PLLA composite PDA-DOX (PLLA@PDA-DOX) nanobubbles with integrated functions of ultrasound imaging, photothermal therapy, and chemotherapy. The fabricated nanobubbles exhibited a uniform mean diameter of 489.30 ± 6.96 nm with a Polydispersity index (PDI) of 0.226 ± 0.01 and a DOX loading efficiency of 3.27%. Acute toxicity evaluation in mice revealed that the maximum tolerated dose of PLLA@PDA-DOX nanobubbles was markedly higher than the clinical equivalent dose, showing no detectable toxicity or allergic reactions. Under near-infrared (NIR) laser irradiation, the inhibition rate of HCCLM3 cells increased from 50.1% to 64.45%, indicating enhanced therapeutic efficacy through the combined effects of photothermal therapy and chemotherapy. Moreover, compared with the free DOX group, the survival rate of LX-2 cells in the composite nanobubble group significantly increased from 18.9 ± 1.56% to 68.8 ± 3.08%, suggesting that the PLLA@PDA-DOX nanobubbles effectively reduced the direct cytotoxicity of DOX by preventing its immediate contact with cells. Collectively, the results confirm that PLLA@PDA-DOX nanobubbles possess excellent biocompatibility, robust ultrasound imaging performance, and enhanced antitumor efficacy under NIR irradiation. This multifunctional nanosystem demonstrates promising potential as an integrated platform for simultaneous cancer diagnosis and therapy. Full article

Weld-bonded joints combine localized metallic welding with structural adhesives and are increasingly used in lightweight multi-material structures. Although numerous studies have examined individual weld-bonding processes, the available literature remains fragmented with respect to process classification, adhesive–weld interaction and mechanical performance. This paper presents a critical review of hybrid weld-bonded joints published between 2000 and 2026, with emphasis on welding-based joining processes and their influence on joint behavior. The main weld-bonding techniques, including resistance spot weld-bonding (RSWB), friction stir weld-bonding (FSWB), friction stir spot weld-bonding (FSSWB) and laser weld-bonding (LWB), are systematically compared in terms of heat input, adhesive stability, load transfer mechanisms and mechanical performance. The analysis indicates that processes with lower heat input, such as FSWB and FSSWB, provide improved adhesive preservation and fatigue performance, whereas RSWB remains the most industrially established solution. The influence of different adhesive families (epoxy, polyurethane, acrylic and thermoplastic) is evaluated with respect to thermal resistance, rheological behavior during welding and long-term durability. Mechanical performance under static, fatigue and impact loading is critically assessed, highlighting typical strength improvements compared with purely welded joints and identifying dominant failure modes. In addition, numerical modeling approaches, including finite element and cohesive zone methods, are reviewed in terms of their ability to capture coupled thermomechanical and damage phenomena. The review further outlines key industrial applications, current technological limitations and future research directions, including advanced adhesive systems, low-heat-input processes, non-destructive testing and digital-twin-based optimization. Full article

Current manual laser cleaning methods often require highly skilled operators to achieve fast and reliable cleaning. This study investigated the feasibility of measuring thermal processes during laser metal cleaning to support the development of an automated and intelligent laser cleaning system. The measurement system was based on fast infrared (IR) diagnostics and used a field programmable gate array (FPGA) for fast signal analysis. Experiments were conducted on steel substrates covered with paint, scale, or corrosion. Thermal response in real-time for every laser pulse was monitored. Paints showed no solidification plateau, while steel exhibited a clear plateau above the ablation threshold. The scaled surface showed longer time intervals and higher heat accumulation. A histogram of time intervals enabled statistical analysis of the process. Time-resolved temperature values revealed hidden processes. These findings demonstrated the potential of IR thermal diagnostics for evaluating surface conditions and providing real-time data to optimise, monitor, and control laser cleaning processes. Full article

Ultra-precision machining of ferrous alloys remains challenging because conventional diamond tools suffer severe thermochemical wear, whereas ultrasonic vibration-assisted cutting requires complex and costly equipment. This study investigates single-crystal sapphire as an alternative cutting-tool material for ultra-precision machining of both non-ferrous and ferrous metals. A sapphire tool was fabricated from a polished wafer, laser-shaped into an equilateral triangular insert, vacuum-brazed onto a tungsten carbide carrier, and finished by ultra-fine grinding to yield a well-defined cutting edge. Ultra-precision turning experiments were conducted on copper and 420 stainless steel using a Moore Nanotech 350FG lathe, and the performance of the sapphire tool was benchmarked against conventional diamond (copper) and cubic boron nitride (CBN) tools (stainless steel) under comparable cutting conditions. Surface roughness (Ra) and topography were characterized using an optical surface profiler, while scanning electron microscopy and atomic force microscopy were employed to assess tool wear and cutting-edge geometry. The sapphire tool produced mirror-like surfaces with average surface roughness (Ra) values of 6.4 nm on copper and 39.1 nm on 420 stainless steel, compared with 1.3 nm for diamond on copper and 92.9 nm for CBN on stainless steel. Across both materials, sapphire generated regular, stable tool marks and exhibited minimal wear, with no catastrophic edge degradation or clear evidence of severe chemical interaction with the steel workpiece. These results demonstrate that sapphire is a viable tool material for extending diamond turning-level surface quality to stainless steel without ultrasonic assistance. Full article

Carbon fiber-reinforced polymer (CFRP) composites are widely employed in the aerospace industry due to their excellent properties such as high specific strength and corrosion resistance. However, the delamination and tearing of composites are prone to occur in the machining of CFRP, which significantly affect its performance. The existing laser-assisted cutting model generally simplifies the machining process into high-temperature conventional cutting, and only reflects the thermal effect by modifying the material parameters. The core selective ablation characteristics of laser–CFRP interaction are completely ignored, and the unique mechanical behavior of bare fiber under a large cutting angle is not modeled, and the quantitative correlation between cutting force evolution and machining damage is lacking. In this study, an innovative method of partially exposing fibers is proposed to simulate laser-assisted machining. A micromechanical model is developed to analyze the removal mechanisms of different phases during CFRP processing, and a cutting force prediction model from the micro to macro scale is also established. At the micro-scale, a micromechanical model for fiber cutting in orthogonal machining of CFRP is constructed based on the elastic foundation beam theory. The results show that the proposed cutting force prediction model has high reliability, and the relative error between the predicted value and the experimental measured value is only 7.81%~8.99%. All experiments were repeated three times. Statistical analysis showed that the repeatability of the results was excellent. Compared with conventional cutting, laser-assisted cutting fundamentally changed the failure mode of the fiber from matrix-constrained crushing fracture to controllable free-end large-deflection bending fracture. This transformation leads to a smoother and more regular fiber fracture surface, which effectively inhibits fiber breakage, matrix tearing, and fiber–matrix interface debonding. Quantitative analysis confirms that under laser-assisted processing conditions, the matrix tearing length is positively linearly correlated with the cutting depth, cutting speed, and bare fiber length. Full article

With the rapid development of flexible electronics technology, flexible wearable sensors based on Lanthanum Strontium Manganese Oxide (La_1-xSr_xMnO₃) have garnered extensive attention in recent years due to their excellent multi-functional integration, environmental stability and biocompatibility. This review systematically analyzes the preparation methods, process optimization strategies, multi-performance integration technologies, and the expansion of the application field of La_1-xSr_xMnO₃-based flexible sensors. Firstly, the basic characteristics and sensing mechanism of the La_1-xSr_xMnO₃ material were presented, including its temperature sensitivity, strain response characteristics, and magnetoresistance effect. Secondly, the fabrication process of flexible sensors was elaborately discussed, with a focus on analyzing crucial technologies, such as laser induction and transfer printing technology. Subsequently, the strategies for regulating the electrical, thermal, and mechanical properties of materials through element doping, along with the multimodal sensing integration and signal decoupling methods, were expounded. Furthermore, the actual performance of this type of sensor in fields such as health monitoring, human–computer interaction, and extreme environment applications was summarized. Finally, the challenges and future development directions of La_1-xSr_xMnO₃-based flexible sensors are outlined, providing theoretical references for the design and optimization of next-generation flexible electronic devices. Full article

In this study, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) films embedded with silver nanoparticles were fabricated to investigate their antibacterial performance against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Inspired by the nanoscale topographies of natural antibacterial surfaces, such as dragonfly and cicada wings, microstructured pillars were introduced onto the polymer surface to enhance its bactericidal activity by increasing the effective contact area. Surface morphology was characterised using scanning electron microscopy (SEM), including higher-magnification imaging of micropillar surfaces, while energy-dispersive X-ray spectroscopy confirmed the presence of silver. Higher-magnification SEM revealed nanoscale surface features on the micropillars, attributed to embedded or surface-associated silver nanoparticles. Antibacterial performance was evaluated using confocal laser scanning microscopy with live/dead staining. The PVDF-HFP/Ag films exhibited a significant reduction in bacterial viability, particularly against S. aureus (reducing viability to 0.6% ± 1.1%), while showing moderate activity against E. coli (41.0% ± 3.7% viability). While the fabricated micropillars (~5 µm) are larger than bacterial cells and unlikely to induce direct mechanical rupture, they increase surface interaction. To further investigate the theoretical antibacterial mechanism of scaled-down features, finite element analysis (FEA) was performed to model the mechanical interaction between bacterial cells and nanostructured pillars. The simulation results indicated localised stress concentrations that could compromise bacterial membrane integrity, suggesting a possible mechanobactericidal contribution if the microstructures are further reduced to the nanoscale, in addition to the primary biochemical effects of silver nanoparticles. FEA results do not aim to explain the experimentally observed antibacterial performance and should be interpreted only as a conceptual investigation. These findings demonstrate the potential of bio-inspired PVDF-HFP/Ag films as antibacterial materials for food packaging and related applications, subject to future comprehensive toxicity and quantitative microbiological evaluations. Full article

Background and Objectives: To evaluate the impact of Holmium Laser Enucleation of the Prostate (HoLEP) versus Transurethral Resection of the Prostate (TURP) on cognitive function and psychological well-being three months post-surgery. Materials and Methods: This prospective observational cohort study involved 150 patients undergoing surgical treatment for BPH; 132 patients (66 HoLEP, 66 TURP) completed baseline and 3-month follow-up evaluations. The Montreal Cognitive Assessment (MoCA) served as the primary measure of cognitive function, while the Mini-Mental State Examination (MMSE) functioned as a secondary measure. The Beck Anxiety Inventory and Beck Depression Inventory were utilized to assess individuals’ mental states. We employed repeated-measures General Linear Models, adjusted for age and educational attainment, to examine temporal variations. Results: Baseline demographic, clinical, cognitive, and psychological characteristics were comparable among the groups. The modified analysis revealed no significant interaction between time and surgical procedure for MoCA (p = 0.405), indicating that both groups exhibited comparable cognitive trajectories. No significant differences were seen between the groups in the adjusted MoCA scores (p = 0.162). A minor, statistically insignificant temporal effect was observed (p = 0.058; partial η² = 0.028). Educational attainment independently forecasted cognitive performance (p = 0.024). The MMSE demonstrated a slight temporal effect (p = 0.015) with no interaction of approaches. Anxiety and depressive symptoms persisted uniformly and comparably among the groups. Conclusions: Three months post-surgery, neither HoLEP nor TURP was associated with a notable deterioration in cognitive performance. The surgical modality did not independently influence cognitive trajectory after adjusting for demographic variables. Contemporary endoscopic BPH surgery appears to be neurocognitively safe during the medium-term postoperative period. Full article

Ballistic para-aramid fabrics are widely used in personal protection and defense applications due to their high strength-to-weight ratio, thermal stability, and durability. This study investigates the influence of laser-based surface modification on graphene-modified Kevlar^® KM2-600 (600 dtex) fabrics, with a particular focus on surface morphology and topographical characteristics of para-aramid fabrics used in ballistic applications. The deposition of graphene onto para-aramid fibers introduces new opportunities for surface engineering, while laser processing enables localized and controlled modification of the fiber surface without compromising the integrity of the bulk material. In this work, graphene-modified Kevlar^® KM2-600 fabrics were subjected to controlled laser processing under various parameter settings, and the resulting surface modifications were systematically analyzed. Three-dimensional laser microscopy was employed to characterize surface morphology and roughness, providing detailed insight into laser-induced topographical changes. The results demonstrate that optimized laser processing enables controlled surface restructuring while avoiding severe thermal damage, particularly when appropriate mechanical stabilization and focal conditions are maintained. Under identical laser processing conditions (Matrix II, q = 3.65 × 10⁴ W/cm²), the mean arithmetic roughness increased from 4.57 ± 1.04 µm for the unmodified fabric to 5.54 ± 1.05 µm for the graphene-modified fabric, while the mean root mean square roughness increased from 5.76 ± 1.41 µm to 6.95 ± 1.39 µm. These findings contribute to an improved understanding of laser–graphene–aramid interactions and provide a foundation for future studies addressing the potential functional implications of surface modification in lightweight protective textiles. Full article