Search Results (1,882)

Despite extensive research on iron-based metal matrix composites (Fe-based MMCs), an integrated assessment linking fabrication methods, reinforcement architectures, interface engineering, and strengthening mechanisms remains limited. This review summarizes recent advances in Fe-based MMCs, with emphasis on the relationships among processing routes, microstructural evolution, reinforcement characteristics, and mechanical performance. Powder metallurgy, casting, and additive manufacturing are critically compared in terms of their processing characteristics, advantages, limitations, and suitability for iron-based systems. The effects of reinforcement size, morphology, distribution, and volume fraction on composite performance are discussed. Particular attention is given to interface engineering strategies and architectured core–shell reinforcements produced through in situ reactions and solid-state diffusion, infiltration, laser cladding, sol–gel coating combined with additive manufacturing, electrochemical synthesis, and high-energy ball milling. Recent studies indicate that core–shell architectures can offer enhanced control of reinforcement–matrix interactions by combining hard ceramic or carbide phases with more ductile metallic components. Rod-like Me@MeC/Fe (Me = Ta, Nb, W) architectures and dispersed core–shell particles show promising combinations of strength, toughness, and wear resistance, although their performance depends strongly on shell architecture, interface characteristics, and processing conditions. Remaining challenges include reproducible and scalable fabrication, shell architecture control, interface stability, and long-term performance. Further progress may benefit from advanced reinforcement design, additive manufacturing, modelling, and AI-assisted optimization of high-performance Fe-based MMCs. Full article

Zn₂SnO₄ is a promising anode for lithium-ion batteries owing to its high theoretical capacity, yet its practical utilization is severely limited by sluggish reaction kinetics, large volume expansion, and unstable electrode/electrolyte interfaces. Here, we introduce a dimensionality-reduction strategy that simultaneously boosts capacity and cycling stability. Through surfactant-directed crystal growth, acid-etching reconstruction, and hydrothermal carbon coating, compact Zn₂SnO₄ octahedra are controllably transformed into sheet-assembled structures and finally into a core–shell composite with a continuous carbon layer (C@M-Zn₂SnO₄ (H⁺)). The continuous structural evolution shortens Li⁺ diffusion paths, buffers mechanical stress, and stabilizes the solid–electrolyte interface without altering the intrinsic lithium-storage mechanism of Zn₂SnO₄. As a result, the optimized C@M-Zn₂SnO₄ (H⁺) electrode delivers a reversible capacity of 650 mAh g⁻¹ after activation and retains 620 mAh g⁻¹ after 600 cycles at 200 mA g⁻¹, with Coulombic efficiency approaching 100% throughout. This work demonstrates that dimensionality-reduction-assisted structural engineering is an effective strategy for developing high-capacity, long-cycle-life anode materials. Full article

Developing ammonia selective-catalytic-reduction (NH₃-SCR) catalysts that combine excellent activity with hydrothermal stability remains a major challenge in controlling NO_x emissions from diesel engines. In this study, a Cu-SSZ-13@high-silica-SSZ-13 catalyst with a core-shell structure was successfully synthesized via a simple surface self-assembly strategy. Characterization results confirmed that a high-silica SSZ-13 shell uniformly encapsulated the outer surface of the Cu-SSZ-13 core, with a thickness of approximately 50 nm. Performance evaluation demonstrated that CuZ@SSZ exhibited superior low-temperature NO conversion and remarkable hydrothermal stability after aging compared with Cu-SSZ-13. The core-shell catalyst contained a higher content of Z-CuOH species, which enhanced low-temperature NH₃-SCR activity. Furthermore, the hydrophobic high-silica shell effectively shielded the catalyst core from water vapor attack, suppressing framework dealumination and preventing active copper aggregation into inactive CuO_x species during hydrothermal aging. This study presents an effective homoepitaxial core-shell design strategy for highly efficient NH₃-SCR catalysts. Full article

Commercial carbon-based electrodes such as graphite felt and carbon felt in all-vanadium redox flow batteries suffer from inherent drawbacks, including slow vanadium ion redox kinetics, insufficient intrinsic catalytic activity, fiber corrosion, and functional group loss under strong acidic oxidative conditions, significantly limiting battery energy efficiency and long-term operational reliability. Rare-earth elements, with their unique 4f electron shell structure, tunable electronic levels, abundant surface oxygen vacancy defects, and strong coordination ability, offer a dual pathway—electronic and microstructural modulation—to optimize the interfacial electrocatalytic behavior of carbon electrodes, providing a novel materials system to overcome electrode performance bottlenecks in vanadium batteries. This review systematically summarizes recent advances in rare-earth-functionalized carbon electrodes and electrocatalysts for vanadium redox flow batteries, elaborating on core modification strategies, performance enhancement trends, and synergistic catalytic mechanisms. It also presents quantitative experimental results from the literature to clearly demonstrate the benefits: CeO₂-modified graphite felt at 0.2 wt% shows a 10.8% increase in energy efficiency compared to pristine graphite felt at a current density of 200 mA·cm⁻², while multi-rare-earth co-doped carbon electrodes achieve a 65% reduction in charge transfer resistance relative to unmodified electrodes. The review systematically categorizes two dominant modification routes—surface nano-decoration with rare-earth oxides and lattice bulk doping with rare-earth elements—and summarizes design principles and enhancement mechanisms of diverse composite catalytic systems, including rare-earth–carbon nanocomposites, rare-earth-based heterojunctions, and porous rare-earth catalysts. It further analyzes critical challenges in current research, such as unclear long-term stability mechanisms, high costs of high-purity rare-earth raw materials, immature large-scale fabrication processes, and limited in situ dynamic characterization techniques. Compared with existing reviews, this work clearly distinguishes between surface loading and lattice doping as two distinct rare-earth modification approaches, clarifying their differences in active site formation, electronic regulation logic, and cycling stability. It establishes a comprehensive theoretical framework for the coupled electronic–geometric effects in rare-earth-modified carbon electrodes, linking the intrinsic physicochemical properties of rare earths, material microstructure design, and battery electrochemical performance. Moreover, it innovatively proposes a pathway toward full-lifecycle recycling and reuse of rare-earth-based catalytic electrodes for industrial implementation. This review provides a complete theoretical foundation for developing high-performance, long-cycle, low-cost vanadium redox flow battery electrode materials and supports their engineering scale-up, contributing to the development of large-scale, long-duration energy storage technologies. Full article

Nanoscale zero-valent iron (nZVI) exhibits great potential in the field of organic pollutant remediation due to its strong reducibility, high specific surface area and unique core–shell structure. However, pristine nZVI has inherent drawbacks including severe particle aggregation, surface passivation and poor electron selectivity, which greatly restrict its practical remediation performance. To improve the reactivity of nZVI, researchers have developed multiple modification approaches that significantly improve the dispersibility, stability and reactivity of nZVI. This review summarizes the main nZVI modification strategies, including metal modification, surface coating, carrier loading, sulfidation modification and biological integration. The advantages and limitations of each modification method are compared. Furthermore, the underlying removal mechanisms of modified nZVI toward typical organic pollutants are elaborated, covering direct reduction, advanced oxidation and synergistic degradation pathways. Key factors governing the degradation efficiency of modified nZVI are subsequently analyzed. Finally, existing bottlenecks for practical implementation and future research perspectives are proposed. Full article

Aluminum matrix composites reinforced with refractory medium-entropy alloy particles are of growing interest for wear-resistant applications, yet the contribution of an oxidized core–shell reinforcement remains largely unexplored. This study investigates the fabrication and tribological performance of Al composites reinforced with WMoNb refractory medium-entropy alloy (RMEA) powder and its oxidized derivative (RMEO). Equiatomic WMoNb powder was synthesized by 150 h high-energy ball milling, forming a single-phase BCC solid solution, then oxidized at 650 °C/4 h, selectively converting Mo and Nb into Mo₄O₁₁ and NbO_0.76 while W remained metallic, yielding a core–shell RMEO structure. Composites containing 2.5–10 wt.% RMEA or RMEO were fabricated by cold pressing/sintering and evaluated by dry sliding wear testing (pin-on-disc, Al₂O₃ counterpart). Both reinforcements reduced friction and wear loss relative to pure Al in a dose-dependent manner; RMEO outperformed RMEA at every ratio, cutting friction and wear loss by ~60% at 10 wt.% and reaching the highest hardness (132 HB) of all compositions. Worn-surface and profilometric analyses revealed a wear-mechanism shift from severe adhesive/abrasive wear in pure Al to a tribo-oxide-mediated regime in RMEO composites. These findings indicate that selective oxidation of refractory medium-entropy alloy powders is an effective strategy for enhancing the wear resistance of Al matrix composites. Full article

Metallic and organometallic nanoparticles exhibit intriguing size- and morphology-dependent magnetic properties that differ markedly from their bulk counterparts. Here, we report a detailed synthesis and characterization of iron (Fe), copper (Cu), nickel (Ni), and cobalt (Co) nanostructures dispersed in carbon matrices derived from phthalocyanine (Pc), tetrakis(4-carboxyphenyl)porphyrin (TCPP), and tetraphenylporphyrin (TPP), with the detailed quantitative analysis focused primarily on iron phthalocyanine (FePc), iron tetrakis(4-carboxyphenyl)porphyrin (FeTCPP), and iron tetraphenylporphyrin (FeTPP). Using powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS), and magnetometry, we systematically investigate how precursor composition, annealing conditions, and nanostructure formation impact the resulting magnetic behaviors. We introduce a validation-aware image-analysis workflow for morphological, local periodic-contrast, and two-dimensional connectivity descriptors while distinguishing these image-derived quantities from direct measurements of bulk crystallinity, porosity, and three-dimensional connectivity. Hysteresis measurements at low temperatures reveal that iron-based compounds, particularly iron phthalocyanine (FePc) and iron tetrakis(4-carboxyphenyl)porphyrin (FeTCPP), exhibit notable saturation-like magnetization and stronger coercivity, respectively, whereas other precursors (e.g., Cu tetraphenylporphyrin, CuTPP) show weaker magnetic responses. These contrasting behaviors underscore the importance of understanding how candidate phase composition (e.g., metallic Fe, graphite-like carbon, or iron-carbide-related contributions), local morphology, and carbon structure correlate with magnetic characteristics. Microscopy and EDS support Fe-rich regions dispersed within carbonaceous matrices, and a representative Fe/O/C STEM–EDS field provides local evidence for a core–shell-like morphology without establishing a uniform shell thickness, composition, or local core phase across the full population. Our findings highlight the feasibility of tuning carbon–metal nanocomposites through controlled synthesis and post-annealing, thereby motivating future application-specific evaluations in areas such as magnetic hyperthermia, drug delivery, sensing, and electromagnetic materials. The image-analysis workflow also offers a reproducible framework for future studies seeking to relate nanoparticle morphology and magnetic properties to controlled processing. Full article

Aluminum nanoparticles (ANPs) possess a core–shell structure, yet the coupled roles of atomic stress and interfacial charge transfer in their slow-heating oxidation remain elusive. This study employs ReaxFF molecular dynamics simulations to investigate the oxidation of six core–shell ANPs with different particle sizes (5–10 nm) and shell thicknesses (0.5–2.0 nm) from 300 K to 1400 K. Results reveal that the stress evolution dictates the oxidation pathway. Thin shells (0.5–1.0 nm) undergo a compressive-to-tensile stress transition, leading to shell rupture at ~1060 K and subsequent outflow and rapid oxidation of Al into clusters, while thick shells (1.5–2.0 nm) maintain compressive confinement, preventing rupture but resulting in incomplete oxidation (58–84%). Mean squared displacement indicates earlier atomic diffusion onset for thin-shell particles (~7 ps) compared to thick-shell ones (~15 ps). Significantly, interfacial charge redistribution provides the electronic driving mechanism: thin shells facilitate charge homogenization and electron loss, lowering diffusion barriers, whereas thick shells sustain distinct charge separation, impeding atomic migration. These findings provide a theoretical basis for the atomic-scale stress–charge–diffusion coupling mechanism, offering crucial insights for the safety assessment and structural design of oxidation-resistant ANPs. Full article

The growing interest in bio-based and bioactive materials, as well as sustainable production techniques, has driven the development of multifunctional hybrid systems. This study reports the fabrication of novel microcapsules with a double-layer alginate–PEG–chitosan shell, with or without a core, via coaxial electrospraying, followed by ionotropic gelation and polyelectrolyte complexation. PEG1000 and PEG1500 were incorporated into the shell as phase change materials, and thyme oil–oleic acid served as a hydrophobic bioactive core. Scanning electron microscopy and Fourier transform infrared analyses confirmed the structural integrity and effective shell–core integration. Thermogravimetric analyses showed enhanced thermal stability in double-layer alginate–PEG–chitosan biopolymer network shell and thyme oil included core system, with a delayed degradation up to 370.0 °C and reduced mass loss compared to the alginate–chitosan control sample. Differential scanning calorimetry over ten heating–cooling cycles demonstrated significant phase transition enthalpies (70.5–91.8 J·g⁻¹ at 37.6–48.5 °C), confirming efficient thermal energy storage and release governed by the PEG content. Aqueous suspensions prepared from microcapsules exhibited reversible temperature-dependent swelling–deswelling behavior between 20.0 and 55.0 °C, governed by hydrogel properties of the alginate–chitosan shell interactions. The microcapsules exhibited pronounced pH-dependent swelling (enhanced at pH 7.0), high water solubility, and good antioxidant activity. These findings highlight the broad application potential of bio-based shell–core microcapsules, e.g., active food packaging, biomedical dressings, protective coatings, pharmaceutical and biomedical delivery systems and functional textiles. Full article

Wearable sweat biosensors require electrode materials with high surface area, conductivity and mechanical compliance, yet chemically polymerized polyaniline forms dense, low-surface-area films with limited flexibility. In this work, flexible free-standing nanofiber mats were fabricated by coaxial electrospinning, using a sulfuric-acid-doped polyacrylonitrile/polyaniline (PAN/PANI) core and a shell containing graphene oxide nanoscrolls (GONS) at 1 and 3 wt%, followed by gold nanoparticle and ferrocene incorporation, glucose oxidase (GOx) immobilization and a Nafion coating. Scanning electron microscopy showed uniform bead-free fibers with an interconnected pore network and an apparent image-derived porosity of approximately 40%. Energy-dispersive X-ray spectroscopy confirmed the uniform distribution of carbon, oxygen, nitrogen and sulfur across the matrix. Fourier-transform infrared spectroscopy retained the nitrile band at 2243 cm⁻¹ and the quinoid and benzenoid bands at 1547 and 1476 cm⁻¹, while amide bands at 1730 and 1641 cm⁻¹ confirmed retention of protein from enzymes. X-ray diffraction gave crystallinities of 76.6% for GONS and 60% for the pure PANI. Four-point probe measurements showed conductivity increasing from 0.0481 S/cm to 1 wt% GONS to 0.0595 S/cm for the 3 wt% mat with additives. These material and structural characterizations establish a promising foundation for future electrochemical validation and sensor development. Full article

Multiphase swirling flows in confined spaces induce highly destructive, nonlinear fluid–structure interaction (FSI) vibrations. Understanding the underlying physical mechanisms is critical for ensuring the safety of industrial operations. This study proposes a mesoscopic multiscale framework coupling the Multi-Relaxation Time Lattice Boltzmann Method with Large Eddy Simulation (MRT-LBM-LES) and the Flügge thin-walled cylindrical shell equations to analyze two-way FSI responses. Variational Mode Decomposition (VMD) and the Hilbert–Huang Transform (HHT) are employed to decouple non-stationary broadband excitation signals. The macroscopic topological evolution of the swirling air core—from initial depression to critical breakthrough—is accurately captured. Dynamic mapping reveals a strict time-domain phase-locking mechanism between macroscopic flow instability and microscopic high-frequency structural excitation caused by cavitation bubble collapse. Furthermore, a dimensionless cross-scale energy cascade index is defined to quantify energy transfer. Results indicate that while higher discharge flow rates delay the critical breakthrough, they trigger a delayed, high-amplitude step mutation in the energy cascade, amplifying the global cumulative excitation energy by nearly 75%. Notably, the dominant high-frequency excitation consistently converges within a narrow band of 760 Hz to 790 Hz, independent of flow rate variations. These findings provide a theoretical foundation for unsteady excitation source localization and targeted vibration reduction in complex industrial pipeline networks. Full article

Vascular stent implantation is a major treatment for vascular diseases, yet postoperative infection and persistent inflammation increase the risk of in-stent restenosis. Herein, core–shell structured PCL/PEO-PVP fiber membranes co-loaded with ciprofloxacin hydrochloride (CIP) and curcumin (CUR) were fabricated via coaxial electrospinning. Orthogonal experiments were conducted to optimize critical spinning parameters through multi-index comprehensive evaluation. Characterizations confirm intact core–shell architecture and stable polymeric backbone structure. In vitro release tests reveal sequential drug-delivery behavior: a rapid initial release of hydrophilic CIP and a delayed sustained release of hydrophobic CUR were observed, contributing to early-stage antibacterial and long-term anti-inflammatory effects, respectively. The “antibacterial zone” method verifies favorable antibacterial activity against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). ELISA results demonstrate the enhanced anti-inflammatory capacity of the dual-drug-loaded coaxial fiber membrane. Cellular assays confirm satisfactory cytocompatibility, and endothelial cells achieve normal proliferation and exhibit typical polygonal morphology on the membrane surface. This dual-drug-loaded coaxial-fiber membrane realizes coordinated sequential antibacterial and anti-inflammatory properties, which provides a feasible strategy for developing functional coatings toward vascular stents. Full article

Accurately identifying influential nodes is essential for analyzing network structures and optimizing information propagation. Existing methods predominantly rely on single indicators such as degree, H-index, or k-shell, inherently limiting their ability to capture a node’s true influence. Recent hybrid centrality approaches attempt to address this by combining multiple local and global attributes; however, they typically integrate features through simple weighting or superposition, failing to characterize the intrinsic synergy among structural properties. Furthermore, they often quantify neighbor contributions too coarsely, overlook the regulatory role of edge strength, and some suffer from high computational complexity, limiting scalability. To overcome these deficiencies, we propose WKDH, a novel influential node identification method based on multi-attribute neighbor contributions. WKDH fuses local structural attributes (degree and H-index) with global structural attributes (k-shell) via a multiplicative weighted synergy model, simultaneously capturing local connection “quantity,” local connection “quality,” and global core-layer position. By transforming neighbors’ comprehensive characteristics into regulated contribution degrees, WKDH mitigates excessive self-attribute interference and accurately reflects the actual propagation potential of edges. Notably, the method achieves linear computational complexity of $O\left(m\right)$. Experimental results on nine real-world and six artificial networks demonstrate that WKDH outperforms nine established indicators in terms of node influence ranking, identification of high-influence nodes, and measuring propagation capability. Moreover, WKDH exhibits strong universality across diverse network structures, as it operates without parameter tuning. Full article

Traditional petroleum coke-based porous carbons suffer from low specific surface area, insufficient surface active sites, and inferior rate and cycling performance. Herein, a series of sulfur/fluorine-co-doped hierarchical porous carbon (S+F-PC) cathode materials were synthesized controllably from industrial solid-waste petroleum coke via KOH high-temperature activation and heteroatom doping strategies. Polyaniline/carbon nanotube (PANI/CNTs) core–shell composites were fabricated as anodes through in situ oxidative polymerization, and S+F-PC//PANI/CNT asymmetric aqueous supercapacitors were assembled. The structural and chemical modulation mechanisms of dual heteroatom doping, as well as the electrochemical energy storage kinetics of electrodes and devices, were systematically investigated using SEM, TEM, XRD, XPS, BET, CV, GCD, EIS, and long-cycle tests. The results verify the synergistic modification effect of sulfur and fluorine co-doping. S-induced lattice distortion creates abundant mesopores and pseudocapacitive active sites, while F atoms stabilize the carbon skeleton to avoid high-temperature structural collapse and enhance the graphitization degree. The optimized S+F-PC exhibits an interconnected micropore–mesopore–macropore hierarchical network and a specific surface area of 172.2 m²/g, delivering a high specific capacitance of 477 F/g at 1 A/g, outperforming pure PC, and single-S-doped and -F-doped counterparts. The PANI/CNTs core–shell structure effectively alleviates the volume expansion of PANI during cycling, and the one-dimensional CNTs form a continuous conductive network. The PANI/CNT anode achieves a specific capacitance of 417 F/g, with a capacity retention of 91.4%, after 10,000 cycles. The assembled asymmetric supercapacitor realizes a stable voltage window of 1.6 V. It presents a specific capacitance of 117 F/g at 1 A/g, a maximum energy density of 41 Wh/kg at a power density of 2000 W/kg, and 87.2% capacity retention after 10,000 cycles. This work provides a feasible strategy for the high-value recycling of industrial-waste petroleum coke and the design of high-performance heteroatom-doped carbon electrodes and matched asymmetric aqueous supercapacitors. Full article

The reverse water–gas shift (RWGS) reaction is a promising route for converting CO₂ into CO, an important feedstock for synthetic fuels and chemicals. In this study, Zn–Co zeolitic imidazolate frameworks (ZIFs), including ZIF-8, ZIF-67, ZIF-67-8, and the core–shell structures ZIF-8@67 and ZIF-67@8, were synthesized as catalyst precursors and thermally activated prior to catalytic testing. Transmission electron microscopy and elemental mapping confirmed the formation of well-defined core–shell architectures, while synchrotron X-ray diffraction verified the characteristic sodalite-type framework. Thermogravimetric analysis revealed substantial framework decomposition during activation at 700 °C. In situ time-resolved X-ray absorption spectroscopy (TR-XAS) showed that Zn remained predominantly in the Zn²⁺ state throughout heating, whereas Co²⁺ underwent progressive reduction to metallic Co⁰ at temperatures approaching 600 °C. Ex situ X-ray absorption spectroscopy confirmed the presence of Zn²⁺ species and metallic cobalt after activation. Catalytic testing of the activated ZIF-derived materials showed that Co-containing catalysts exhibited significantly higher RWGS activity than Zn-only ZIF-8-derived catalyst. Among the investigated samples, ZIF-67@8_C-500 achieved the highest performance, producing 2.50 μmol CO (equivalent to 50 μmol g⁻¹ catalyst) at 600 °C with a H₂/CO₂ ratio of 2:1. The strong dependence of activity on ZIF-67 core loading indicates that metallic cobalt generated from the Co-rich core plays a dominant role in CO₂ conversion. Thermal activation transformed the highly porous ZIF precursors into metallic Co-containing carbonaceous catalysts. The resulting structural evolution, rather than retention of the original porous MOF framework, governed the catalytic performance in the RWGS reaction. Full article