Search Results (17,516)

Self-supported electrodes that combine high activity, durability, and low-cost manufacturing are essential for scalable alkaline water electrolysis. Here, we report a one-pot, high-current-density electrodeposition platform that grows Ni-rich bimetallic catalysts directly on a carbon fabric derived from a mass-produced bamboo-cellulose kitchen wipe (bamboo-derived carbon fabric, BCF). Using a single NiCl₂/NH₄Cl base bath containing 5 mM of a selectable secondary metal ion (Ce, Fe, W, or Mo), galvanostatic deposition at 1 A cm⁻² for 15 min produces conformal polycrystalline catalyst shells on the individual carbon fibers. The Ce-containing cathode (BCF@NiCe) delivers hydrogen evolution overpotentials of 96.8 mV at 20 mA cm⁻² and 222 mV at 1 A cm⁻², rivaling a Pt/C benchmark on the same substrate at industrially relevant current densities, which is attributed to the cooperative interface between metallic Ni and nanocrystalline, oxygen-vacancy-rich CeO_2−x together with a superhydrophilic fibrous architecture that releases fine H₂ microbubbles. Adding Fe to the same bath yields a Ni–Fe–Ce anode (BCF@NiFeCe) that outperforms a RuO₂ benchmark for oxygen evolution above 0.1 A cm⁻² (η = 312 mV at 0.1 A cm⁻²) with a Tafel slope of 60 mV dec⁻¹. Both electrodes operate stably for 200 h of continuous electrolysis, with the Ni/CeO_2−x nanostructure, the oxygen-vacancy population, and the surface chemical states fully preserved after the test, and the same protocol extends to Ni–W and Ni–Mo on nickel foam, establishing a versatile, low-cost route to high-current-density electrodes for green hydrogen production. Full article

This research addresses the critical challenge of “strength regression” observed in alkali-activated binders synthesized from glass wool wastes. In our preliminary studies, while sodium-based activation provided impressive initial strength, the specimens suffered a systematic and significant decline in mechanical performance at 3, 7 and 28 days, exhibiting a 74.3% strength reduction down to 24.61 MPa. Investigative analysis revealed that this instability is closely correlated with the physical degradation and micro-cracking observed in SEM micrographs, which is consistent with the literature regarding high silica-to-alumina network imbalances. To resolve these structural flaws, the precursor blend was modified by incorporating Class F fly ash and metakaolin to rebalance the Si/Al ratio. The addition of these aluminosilicate sources facilitated the consumption of excess sodium ions through enhanced geopolymerization and provided a micro-filling effect that refined the pore structure. Our findings demonstrate that this optimization not only prevents the subsequent loss of strength but also ensures stable compressive strength development up to 28 days without subsequent regression, reaching an ultimate average strength of 110.81 MPa. This approach provides a viable pathway for transforming insulation glass wool waste into high-performance, durable construction materials. Full article

The transition toward a sustainable hydrogen economy demands cost-effective, durable, and highly active catalysts that span the entire H₂ value chain from green production through storage and transport to end-use conversion. Carbon-based catalytic materials have emerged as a uniquely versatile platform, offering tunable electronic structure, abundant defect- and edge-derived active sites, hierarchical porosity, chemical robustness, and compatibility with both metal-free and single-atom architectures. This review provides a comprehensive overview of advanced carbon-based catalysts designed for the hydrogen economy. We begin with the fundamentals of heteroatom doping, defect and curvature engineering, and M–N₄/M–N₃ coordination environments that govern binding of hydrogen-relevant intermediates (ΔG_H*, ΔG_OH*, ΔG_O*). Three application pillars are then systematically examined: (i) hydrogen production through HER and OER across PEMWE, AEMWE, AWE, and SOEC platforms, including emerging seawater and biomass-/waste-coupled electrolysis; (ii) hydrogen storage and chemical carriers, encompassing physisorption on porous carbons and catalytic (de)hydrogenation of liquid organic hydrogen carriers, ammonia, and formic acid; and (iii) hydrogen utilization in PEMFCs, AEMFCs, direct liquid fuel cells, and hydrogen-coupled CO₂ and N₂ reduction. Particular emphasis is placed on structure–activity descriptors, operando mechanistic probes, device-level benchmarking from rotating-disk electrodes to membrane-electrode assemblies, and techno-economic considerations including the levelized cost of hydrogen. We conclude by highlighting critical challenges—carbon corrosion, PGM-free durability, and scalable synthesis—and outline future directions that integrate AI-accelerated discovery, atomic-precision synthesis, and biomass-derived circular-economy carbons for next-generation hydrogen technologies. Full article

Background: Current guidelines recommend mitral valve (MV) repair over replacement for active native valve endocarditis. However, traditional techniques involving radical debridement and prosthetic patch reconstruction may limit repair feasibility and long-term durability. This study evaluates the long-term clinical outcomes of an alternative approach utilizing a limited resection and non-patch technique in patients presenting with active native MV endocarditis. Methods: Consecutive patients with definite active native MV endocarditis who underwent surgical treatment between January 2016 and December 2021 were retrospectively reviewed. From this cohort, all patients managed with MV repair using a limited resection strategy without patch plasty were selected and compared to patients undergoing MV replacement after radical resection. The prespecified primary endpoints were overall mortality, the incidence of recurrent endocarditis, and the rate of reoperation during five-year follow-up. The Cox proportional hazards model was used to identify predictors of overall mortality and adverse events (composite of death, recurrence, and/or reoperation). Results: Out of 128 patients with active native MV endocarditis, 75 patients successfully underwent MV repair via the limited resection and non-patch technique and 53 patients received MV replacement. Five-year mortality rates were 43% in the repair group and 52% in the replacement group, p = 0.31. Six patients developed recurrent endocarditis in the repair group, while one patient developed it in the replacement group. Reoperation was necessary in five cases in the repair group, while one patient in the replacement group required reoperation due to paravalvular leakage. Surgical strategy was not associated with mortality or adverse events. Staphylococcal endocarditis was a strong predictor of overall mortality (HR: 2.2 (1.3–3.7)) and adverse events (HR: 2.2 (1.0–4.9)). Conclusions: A limited resection approach for active native MV endocarditis appears to be a feasible surgical strategy to enhance valve reparability, particularly in non-staphylococcal cases. Conversely, staphylococcal endocarditis remains a potent independent risk factor associated with increased mortality and adverse events. Full article

This study presents a physics-informed, climate-responsive model for predicting carbonation depth and compressive strength degradation in conventional and sustainable cementitious composites under real environmental exposure. The Semi-Theoretical Predictive Degradation (STPD) model couples hourly temperature, relative humidity, and CO₂ concentration data with two-dimensional diffusion–reaction equations implemented in FEniCS. The model accounts for humidity-sensitive diffusivity, temperature-activated carbonation kinetics, and CO₂ consumption via Langmuir decay. Experimental validation was performed on ordinary Portland cement (OPC) concrete specimens exposed for 30 days to climate profiles representative of Portugal (average 14.2 °C, RH 74%, CO₂ ~417 ppm) and Slovakia (average 4.7 °C, RH 80%, CO₂ ~414 ppm). Carbonation depth increased from 0 to 0.30 mm in Portugal and up to 0.15 mm in Slovakia, with corresponding predicted reductions in compressive strength relative to the corresponding uncarbonated reference of up to 25% and 14%, respectively. The STPD model accurately reproduced these trends, achieving RMSE values of 0.008 mm for carbonation depth and 1.55 MPa for compressive strength in OPC concrete. To assess the broader applicability of the framework, simulations were extended to fly ash/slag-blended, geopolymer, and biochar-containing concretes using material-specific parameters. Among the simulated systems, geopolymer concrete showed the highest predicted durability, with carbonation depths below 1 mm and strength loss below 10%. A degradation index combining carbonation depth and strength loss mapped high-risk zones near the exposed surface, particularly under warm and fluctuating climatic conditions. The model provides a transferable framework for climate-informed durability assessment, material selection, and the design of sustainable cementitious composites. Full article

The sturdy and stable unique polyhedral structure of FeOOH nanoparticles facilitates stress and load transfer, thereby forming a tighter mechanical interlock at the carbon fiber–matrix interface. In this work, the FeOOH nanocrystal layer in situ grown on flexible carbon fiber cloth was rationally designed and fabricated through hydrothermal synthesis. Then, the non-covalent cation–π bond was constructed at the interface between the iron ion-loaded FeOOH nanoparticles and indole-based poly(hexahydrotriazine) (In-PHT). Owing to the collaborative effects of physical anchoring and chemical bonding, the resultant composite exhibited an outstanding tensile strength of 322 MPa, and the friction coefficient significantly decreased by 63% compared with the composites without FeOOH nanoparticles. Moreover, the resultant worn composite showed an excellent self-healing property owing to the introduction of polyethylene wax (PEW) with a low melting point, and the healed friction coefficient remained almost unchanged. Extensive analyses verify that the phase-separated structure and Fe³⁺–π interactions across multiscale interfaces achieve the combined advantages of wear resistance and durability for recyclable carbon fiber-reinforced poly(hexahydrotriazine) composites (PHT-CFRPs). Full article

The increasing generation of construction and demolition waste, along with the depletion of natural aggregates, has driven growing interest in recycled concrete aggregate (RCA) and reclaimed asphalt pavement (RAP) as sustainable alternatives in concrete production. However, a direct and systematic comparison between the two materials remains limited. This review addresses this gap by applying PRISMA guidelines to analyze 82 peer-reviewed studies published between 2010 and 2026. Both materials are evaluated across three key domains: physical properties, mechanical performance, and microstructural characteristics. The findings indicate that RCA can reduce compressive strength by up to 26%, mainly due to the presence of porous adhered mortar and a complex interfacial transition zone (ITZ). In contrast, RAP weakens bonding with cement paste because of its hydrophobic bituminous coating, leading to adhesive failure at the mortar asphalt interface. Despite these limitations, RCA and RAP exhibit distinct behaviors in terms of shear capacity, ductility, energy absorption, and durability. Enhancement techniques such as surface treatment, carbonation, supplementary cementitious materials, and fiber reinforcement show potential in improving performance. Additionally, life cycle and economic analyses reveal that RAP can reduce total costs and carbon emissions when efficiently processed. This study provides a unified comparative framework to support sustainable material selection and design optimization. Full article

Global plastic waste generation and excessive sand extraction are major environmental challenges, but replacing fine aggregate with plastic waste often degrades concrete performance. This work characterizes concrete incorporating recycled HDPE and PET fine aggregates at a 10% volumetric replacement level, with and without polymer-specific surface treatment, across fresh, mechanical, and durability properties. Untreated plastic aggregate generally lowered mechanical performance due to low polymer stiffness, weak plastic–paste bonding, and greater interfacial void formation. Surface treatment partially offsets these effects by strengthening the plastic–paste bond. H₂O₂-treated HDPE granules recovered the 28-day elastic modulus to within 3% of the control while also improving compressive strength, ultrasonic pulse velocity, and freeze–thaw resistance. H₂O₂-treated HDPE chips showed the highest electrical resistivity and the lowest permeable void content. NaOH-treated PET chips gave the lowest chloride penetrability and the greatest drying shrinkage reduction, approximately 25% relative to the control, though NaOH produced no resistivity gain for PET-C. Freeze–thaw durability factor increased with surface treatment for HDPE-G and PET-C, with HDPE-G-T exhibiting the highest durability factor among the recycled plastic mixtures at 94.20%. These results show that surface-treated recycled HDPE and PET fine aggregate can be incorporated at 10% replacement while maintaining acceptable mechanical and durability performance, supporting recycled plastics as a viable partial fine-aggregate replacement. Full article

The development of high-density cementitious composites is critical for specialized applications such as heavy-duty structural components. This study investigates the impact of replacing silica sand with barite powder on the physical, mechanical, and microstructural properties of cementitious composites. The replacement levels varied from \0% to 100% to evaluate the extent of property modification. Experimental results indicate a significant positive correlation between barite content and composite density, which increased by 17.6% to reach a maximum of 2857 kg/m³ at 100% replacement. However, this densification was accompanied by a systematic degradation in mechanical performance. At the 100% replacement level, compressive, tensile, and flexural strengths decreased by 26.4%, 30.2%, and 34.1%, respectively. Furthermore, water absorption nearly doubled, increasing from 1.9% in the control to 3.8% in the 100% barite mix. Scanning Electron Microscopy (SEM)-based microstructural observations suggest that the decline in mechanical performance and the increase in permeability are consistent with weak aggregate–matrix adhesion. The study concludes that while barite is highly effective for increasing composite density, the resulting increase in porosity and loss of cohesive strength must be carefully managed through mix optimization to ensure structural durability. Full article

To explore the emerging role of natural ligands, specifically coumarin and curcumin, and their coordination with the transition metals ruthenium (Ru) and iridium (Ir) as photosensitizers (PSs) in photodynamic therapy (PDT) for cancer. This highlights the integration of natural compounds and transition metals to overcome limitations in photophysical properties, hypoxia tolerance, and clinical translation. Regarding PDT oncology, this examines an immunological effect on Ru/Ir complexes and natural ligand–metal hybrids. They induce immunogenic cell death (ICD) through reactive oxygen species (ROS) generation, calreticulin exposure, extracellular ATP release, and HMGB1 secretion. These damage-associated molecular patterns act as “danger signals” to recruit dendritic cells, prime CD8⁺ cytotoxic T-cells, and establish systemic antitumor immunity. This study compares natural ligand–metal complexes with conventional Ru(II)/Ir(III) complexes and clinical PSs to assess their translational potential as immune-activating agents in PDT oncology, as well as focusing on the integration of nanotechnology with natural ligand–metal complexes to enhance delivery, biocompatibility, and clinical translation. A narrative review was conducted of the literature published between 2010 and 2025 across multiple electronic databases, including WanFang Data, PubMed, ScienceDirect, Scopus, Web of Science, Springer Link, SciFinder, and CNKI, without language restrictions. Studies focusing on coumarin, curcumin, Ru(II), Ir(III), and PDT were analyzed. Extracted data included chemical structures, absorption and emission spectra, singlet oxygen yields, biological activities, and therapeutic outcomes. Comparative evaluation was performed between free natural ligands, their Ru(II)/Ir(III) complexes, and nanodelivery systems to assess efficacy, biocompatibility, and translational potential. Coumarin and curcumin exhibited intrinsic antioxidant, anti-inflammatory, and anticancer properties but were limited by short absorption/emission ranges, poor photostability, and low singlet oxygen yields, restricting preclinical application. Coordination with Ru(II) and Ir(III) significantly enhanced intersystem crossing, extended absorption into the near-infrared region, and improved singlet oxygen quantum yields (Φ_Δ up to ~0.78). These complexes demonstrated potent photocytotoxicity under normoxia and hypoxia, achieving IC₅₀ values in the nanomolar range, which indicated organelle-specific targeting (mitochondria, lysosomes, ER), induced ICD, and synergized with checkpoint blockade. Nanocarrier encapsulation further improved solubility and tumor selectivity, and reduced systemic toxicity. Coumarin- and curcumin-based Ru/Ir complexes represent promising next-generation or immune-activating PDT agents by combining natural pharmacological activity with superior photophysical performance. The ability to generate reactive oxygen species under hypoxia and achieve multimodal therapeutic effects positions them as strong candidates for clinical translation. Clinical approval of natural ligand–Ru/Ir complexes depends on rigorous safety, pharmacokinetic, and nanodelivery validation, but these complexes clearly extend PDT beyond local cytotoxicity toward durable immune protection. Future research should prioritize ligand engineering, nanotechnology integration, and translational models to bridge preclinical promise with safe and effective clinical applications. Full article

Enhancing the performance of titanium biomaterials remains a critical challenge in the development of durable implant materials, particularly under complex physiological conditions where corrosion processes are influenced by interactions with biological species. Electrochemical oxidation has emerged as a promising approach for generating nanostructured titanium dioxide layers, which can improve corrosion resistance. In this study, nanostructured oxide layers were synthesized on additively manufactured 3D titanium scaffolds via anodization in a fluoride-containing ethylene glycol and water electrolyte. Corrosion resistance was systematically evaluated using open-circuit potential measurements, Tafel analysis, and electrochemical impedance spectroscopy, considering the effects of biological medium composition and prolonged exposure to corrosive conditions. The main scientific contribution of this work is the elucidation of the time-dependent corrosion behavior and electrochemical stability of anodized additively manufactured titanium scaffolds under physiological exposure conditions. The results demonstrated that the medium composition significantly influenced the properties of the anodized materials, primarily due to the adsorption of medium species on the nanostructured surface. Prolonged exposure tests further confirmed the superior durability of the coatings, which is attributed to the formation of a protective protein layer that enhances corrosion resistance in aggressive environments. These findings advance the understanding of time-dependent corrosion behavior in complex biological environments and highlight the effectiveness of nanostructured oxide layers in maintaining the electrochemical stability of titanium biomaterials during prolonged exposure. Combined with additive manufacturing, this approach represents a promising route toward the development of patient-specific implants with enhanced durability and long-term functionality for bone regeneration applications. Full article

Natural fibres, both bio-based and mineral-derived, are increasingly investigated for use in mortar as a means of improving technical efficiency while potentially reducing reliance on synthetic fibres where performance and durability are adequate. This review synthesises mortar-focused evidence across cement-based binders, air lime and natural hydraulic lime binders, gypsum-based binders and clay-based binders, with emphasis on mix designs, fibre–matrix interactions, durability-related behaviours and engineering applications. Across binder systems, the most consistently reported benefit of fibre incorporation is improved crack control and post-crack integrity, provided that fibre dispersion, dosage, and workability are adequately controlled. Some formulations also exhibit reduced measured drying shrinkage, whereas changes in compressive and flexural strength are inconsistent, reflecting the effects of fibre type and content, water demand, density, pore structure and matrix–fibre bonding. Durability is strongly binder- and exposure-dependent. For cement-based mortars, alkaline and calcium-rich pore solution remain key limits for many plant fibres, especially under wetting–drying exposure. For lime-based, gypsum-based and clay-based mortars, chemical attack is generally less severe, but performance and property retention remain sensitive to moisture history, curing path and conditioning. Hygrothermal and hygric effects are conditional and should be considered alongside density, moisture state, pore structure and water uptake. Overall, natural fibres are most convincing when crack control, post-crack integrity, compatibility or moisture-related performance are required, rather than for universal strength or durability improvement. For that, further studies and optimisation are needed. Full article

Concrete is the most used construction material, but its long-term performance depends on durability. Although fly ash has been used as a supplementary cementitious material, the effects of its mechanical activation on the concrete durability require further investigation. This study evaluated the influence of replacing 30% of cement with natural Class F fly ash (NFA) and ground fly ash (GFA) in concrete with a water-to-binder ratio (w/b) of 0.62, using a mixture without fly ash (WFA) as reference. Mechanical activation was performed by milling the fly ash, followed by characterization through particle size analysis and X-ray diffraction. Concrete durability was assessed using electrical resistivity, ultrasonic pulse velocity (UPV), water absorption, porosity, rapid chloride permeability (RCPT), carbonation resistance, and compressive strength tests. Mechanical milling reduced and transformed the ash morphology from spherical to amorphous, while quartz and mullite remained the main crystalline phases. Compared with CNFA, CGFA exhibited up to 101% higher electrical resistivity, 39.6% greater resistance to chloride penetration, 10.8% improved carbonation resistance, 0.4% lower water absorption, and a 5.38% reduction in porosity, although compressive strength decreased by more than 20%. These results demonstrate that mechanically activated fly ash is a viable alternative for enhancing the concrete durability performance exposed to aggressive environments. Full article

Background: Dengue has expanded rapidly beyond traditional tropical and subtropical regions, driven by climate change, urbanization, population mobility, and the spread of competent Aedes vectors. Vaccination is an increasingly important component of dengue prevention, but development has been complicated by four viral serotypes, antibody-dependent enhancement, variable baseline serostatus, and the need for balanced and durable tetravalent immunity. Methods: We conducted a narrative review of PubMed/MEDLINE, Google Scholar, ClinicalTrials.gov, and relevant public health and regulatory sources. Evidence on dengue epidemiology, immunopathogenesis, licensed vaccines, advanced candidates, efficacy, immunogenicity, safety, durability, and implementation was critically evaluated. Priority was given to randomized trials, long-term follow-up studies, regulatory assessments, and surveillance data. Evidence was synthesized descriptively without formal meta-analysis or risk-of-bias assessment. Results: CYD-TDV was the first licensed dengue vaccine but is restricted to individuals with documented previous infection because seronegative recipients may experience an increased risk of severe dengue. TAK-003 has demonstrated overall efficacy against virologically confirmed dengue and dengue-related hospitalization in both baseline-seropositive and baseline-seronegative populations. However, protection is heterogeneous by serotype, and evidence remains limited or uncertain for some serotype-by-serostatus strata. Butantan-DV offers a promising single-dose strategy, but broader use requires additional long-term safety, effectiveness, and serotype-specific data. Inactivated, DNA, viral-vectored, virus-like particle, and mRNA vaccines remain investigational. Conclusions: Dengue vaccination should be integrated with surveillance, vector control, clinical preparedness, and risk communication. Population-based vaccination is most appropriate in high-transmission settings, whereas selective, risk-based strategies are preferable in temperate regions. Continued pharmacovigilance and effectiveness monitoring are essential to guide safe and equitable implementation. Full article

Wood and wood-based materials represent low-carbon sustainable alternatives to petroleum sound absorbers, yet their baseline sound absorption coefficient varies drastically with wood species, anatomical cutting orientation and pore connectivity due to strong structural anisotropy. This review systematically integrates multiscale structural regulation, porous acoustic theories and data-driven optimization into a unified framework, revealing that broadband high sound absorption relies on the synergistic coordination of impedance matching, thermo-viscous dissipation and low-frequency resonant mechanisms, rather than simply maximizing porosity. We quantitatively compare state-of-the-art wood absorbers: directionally frozen wood aerogels achieve near-perfect absorption (α = 0.95–1.00, NRC = 0.82) across 520–6300 Hz, marking the current performance benchmark, while multifunctional superhydrophobic wood aerogels deliver moderate absorption (α ≈ 0.40) but stand out as all-biomass weather-resistant composites. Rigid-frame JCA/JCAL and poroelastic Biot models are clarified for wood’s distinct stiffness characteristics, and existing data-driven approaches are categorized, highlighting that most neural surrogates rely solely on FEM simulation without physical impedance-tube validation. Critical unresolved challenges including poor moisture/fire durability, insufficient industrial scalability and incomplete material databases are summarized, and targeted research priorities covering gradient manufacturing, hybrid physics–machine learning models and lifecycle environmental evaluation are proposed. Full article