Search Results (288)

The development of highly efficient, stable, and cost-effective non-precious metal electrocatalysts to replace conventional platinum-based materials holds profound significance for accelerating the commercialization of advanced energy conversion devices, such as zinc–air batteries (ZABs). Herein, we propose a facile and highly efficient strategy to prepare a defect-rich, highly active nitrogen-doped porous carbon-based electrocatalyst (denoted U-Fe-N-C, urea-assisted iron–nitrogen–carbon material), via high-temperature co-pyrolysis of heme with urea. Our results demonstrate that urea not only serves as an excellent nitrogen source during pyrolysis, introducing abundant topological defects and heteroatom doping sites, but also induces the carbon substrate to form a hierarchical sponge-like porous structure with a high specific surface area. This unique microenvironment effectively prevents the agglomeration of iron species at high temperatures, achieving enhanced dispersion of iron species stabilized within the nitrogen-rich carbon matrix. Electrochemical evaluations reveal that under the optimal synthesis conditions (a precursor mass ratio of 1:3, calcination at 900 °C), U-Fe-N-C exhibits excellent oxygen reduction reaction (ORR) catalytic performance, delivering a half-wave potential of 0.731 V vs. RHE, and shows long-term operational durability that significantly surpasses that of commercial Pt/C. Furthermore, liquid rechargeable zinc–air batteries assembled with U-Fe-N-C as the air cathode deliver remarkable cycling stability, operating for up to 270 h of charge–discharge cycling without noticeable performance degradation. This study not only provides useful insights into the mechanisms of pore formation and assistance but also offers a practical perspective for the rational design and scalable synthesis of high-performance metal–nitrogen–carbon (M-N-C) electrocatalysts. Full article

This case study investigates the rapid through-wall perforation of newly installed hot-dip galvanized (HDG) fire sprinkler pipes in a coastal Mediterranean environment. Failure occurred along the internal waterline of horizontal sections within a short service period. Forensic analysis—comprising metallography, SEM, and EDS—identified a synergistic atmospheric–aqueous corrosion mechanism. Marine aerosol exposure during pre-service storage led to significant chloride enrichment and localized depletion of the 40–50 μm zinc coating, initiating early-stage pitting. Upon commissioning, stagnant water established oxygen concentration gradients and differential-aeration cells, driving localized anodic dissolution. Additionally, sulfate-reducing bacteria (SRB) contributed to accelerated degradation through microbiologically influenced corrosion (MIC), as suggested by sulfur-bearing tubercles. The findings demonstrate that standard galvanizing thickness alone does not ensure longevity in high-salinity environments if atmospheric “preconditioning” occurs. These results underscore the necessity of shielding internal pipe surfaces during storage and construction to prevent premature failure. This case study informs predictive maintenance and material selection for stagnant-water systems in coastal regions. Full article

Vehicle fleet renewal policies promoting NEVs aim to decarbonize transportation but inadvertently alter urban atmospheric corrosivity, threatening the durability of infrastructure coatings. This study investigated the cross-system impacts of vehicle trade-in subsidies on the degradation of protective coatings. We developed a coupled framework integrating a Mixed Logit model for fleet evolution, dynamic Life Cycle Assessment for tracking acidic precursors (SO₂, NO_x), and an Environmental Corrosion Risk Index. Using established Dose–Response Functions, we quantified the lifespan depletion of a standard epoxy zinc-rich primer and polyurethane topcoat system. Our results indicate that aggressive subsidies induce a transition to heavy NEVs, triggering an “emission inversion” that spikes upstream grid acidic emissions. This localized acidification significantly accelerates chemical degradation, reducing the effective service life of infrastructure coatings by 1.3–2.3 years and necessitating premature, costly recoating. We identify a Pareto-optimal subsidy window (8000–10,500 CNY) that effectively balances decarbonization targets with coating preservation. In conclusion, sustainable urban policies must incorporate surface engineering and material durability metrics to prevent emission shifts from compromising the physical integrity of transportation infrastructure. Full article

Historical buildings are highly prone to degradation because they are continuously exposed to the external environment, which represents an extremely aggressive factor. Globally, there are so many historical buildings that need urgent restoration. This paper focuses on finding a new consolidant for real oak old wood and presents a new recipe based on multi-walled carbon nanotubes (MWCNTs) decorated with zinc oxide (ZnO) nanoparticles dispersed in PHBHV solution, aimed at improving old wood properties. The research was conducted on Banloc Castle oak wood, which is predominant throughout the castle. The obtained treatment was applied by brushing onto the wood surface, while the retention and uniform application of the consolidation were confirmed by optical microscopy. One major advantage of the treatment is that the natural color of the wood is not affected, with the total color difference being very small. Another advantage gained after consolidation was the enhanced hydrophobic behavior of the old wood confirmed through water absorption, humidity and contact angle tests. In contrast, untreated wood exhibited hydrophilic behavior and high water and moisture absorption capacity, making aged wood extremely vulnerable to environmental degradation over time. Mechanical tests confirmed that the consolidant solution significantly improved the properties of the wooden material, due to the effective impregnation of the treatment into the wood structure. Furthermore, the MWCNT-based consolidant inhibited the growth of the Aspergillus niger strain, providing antifungal protection and preventing the colonization of microorganisms within the wood structure and its subsequent degradation. Through the methods investigated in this work, it was proven that the treatment is suitable for the consolidation of aged and degraded oak wood materials. Full article

This study characterizes novel cross-linked polymeric composites based on bisphenol A glycerolate dimethacrylate (BPA.DM) as the primary matrix, incorporating 1-vinyl-2-pyrrolidone (NVP) or 2-hydroxyethyl methacrylate (HEMA) as active diluents, and modified with antimicrobial agents: zinc oxide (ZnO), copper(II) sulfate (CuSO₄), nanosilver (Ag), and benzethonium chloride (BEN). Release kinetics of active components into water and LH medium were measured over 20 days using HPLC (bisphenol A, benzethonium chloride), GF AAS (Cu, Zn, Ag), and GC–MS, revealing highest silver release from HEMA+Ag composites (1671 µg/L), substantial copper release from HEMA (354 mg/L) and NVP (319 mg/L) systems, while benzethonium chloride exhibited significantly lower migration. The effect of NVP- and HEMA-containing composites on the metabolism of the Cerrena unicolor was also assessed. Scanning electron microscopy (SEM) and optical profilometry confirmed extensive surface degradation by C. unicolor mycelium, manifesting as cracks, increased porosity, and altered surface across HEMA- and NVP-based composites after 21-day incubation. Biochemical analysis of the fungus post-culture liquids demonstrated that both composite types markedly enhanced extracellular laccase activity at all tested time points (7, 14, 21 days), with ethanol-sterilized samples inducing a slower-migrating laccase isoform identified via zymography. These materials also increased total protein concentration and superoxide anion radical levels while reducing phenolic compounds relative to controls. The findings demonstrate that antimicrobial-modified BPA.DM composites not only undergo controlled biodegradation by C. unicolor but crucially serve as potential laccase inducers, highlighting their dual utility in bioactive material design and fungal enzyme biotechnology. Full article

Water resources face a significant environmental challenge: pollution from microplastics (MP) and heavy metals (HM). These elements pose a dual threat to ecosystems and public health. Microplastics, defined as particles smaller than 5 mm, are of anthropogenic origin, resulting from the degradation of plastics by environmental factors such as solar radiation and friction with the surrounding environment, as well as from their addition to cosmetic and textile products. These materials have been widely detected in drinking water and everyday foods. Heavy metals, high-density elements $(>5{\mathrm{g}/\mathrm{cm}}^3)$, while naturally present in the Earth’s crust, are also generated in large quantities through human activity. Their toxicological risk lies in their ability to accumulate and efficiently move through the trophic chain. Due to the risks to public health and the impacts these pose to ecosystems, it is necessary to continue seeking solutions that enable their monitoring and detection. As a contribution, this work presents a methodology for detecting microplastics and heavy metals in seawater using different machine learning models and an electronic tongue coupled to a sensor network. Two different types of heavy metals, primarily zinc (Zn) and cadmium (Cd), as well as microplastic particles composed of expanded polystyrene (EPS), were detected under controlled conditions simulating different types of water. Atomic absorption spectroscopy (AAS) confirmed the concentrations of the heavy metals studied, supporting machine-learning classification of contaminated waters. Microplastics exhibited strong metal adsorption, influenced by the physicochemical properties of the water. Overall, AUC values above $90\%$ were obtained for seven different models, demonstrating the reliability of the electronic tongue in conjunction with classical machine learning techniques for detecting these elements. Full article

The aim of the study was to modify polylactide with zinc oxide nanoparticles (ZnO), raspberry leaf extract (E), and a combined ZnO/extract system (EZnO) in order to prepare novel packaging materials via a solvent-free method, namely cast extrusion. Physicochemical properties: Morphology (GPC, SEM, FTIR), mechanical (tensile tests, puncture), barrier (WVTR, OTR, UV-Vis) and water contact angle for PLA-based films with two thickness ranges were investigated. Additionally, antimicrobial (antibacterial, antifungal and antiviral) tests were performed. GPC results revealed that the presence of the extract counteracted biopolyester degradation during hot melt processing. The best mechanical properties (TS ca. 50 MPa, EB ca. 18%) were obtained for PLA modified with raspberry leaf extract (PLA/E). EZnO addition led to the highest increase in oxygen (with 25%) and water vapor (up to ca. 28%) barrier properties. The material with EZnO addition was also found to be the only one to demonstrate antibacterial effectiveness, although the activity was insignificant. However, the incorporation of EZnO into the biopolymer matrix enhanced its antiviral properties, resulting in the complete inactivation of Φ6 bacteriophage particles used as a surrogate of SARS-CoV-2 virus. Full article

Bone tissue plays a vital role in the human body and possesses intrinsic self-repair mechanisms; however, large defects or pathological fractures may exceed its natural healing capacity. Bone tissue engineering provides promising strategies to restore bone integrity through the use of scaffolds, growth factors, and stem cells. While calcium phosphate (CaP)-based ceramics, such as hydroxyapatite (HAp) and tricalcium phosphate (TCP), represent the current benchmark, their limitations, including slow degradation (HAp) and limited osteoinductivity (TCP), have driven the development of alternative biomaterials. In this context, magnesium phosphate (MgP)-based materials have gained increasing attention due to their tunable resorption rate, improved biodegradability, and ability to stimulate osteogenesis and angiogenesis through the release of magnesium (Mg²⁺) ions. This study reports on composite scaffolds based on electrospun poly(ε-caprolactone) (PCL) fibres coated with MgP layers doped with lithium (Li) and zinc (Zn), designed to mimic the nanofibrous architecture of the extracellular matrix. Lithium and zinc were selected due to their known ability to modulate cellular response, with lithium promoting osteogenic activity and zinc contributing to improved cell proliferation and antibacterial potential. The phosphate phases obtained by coprecipitation were deposited onto the PCL fibres using Matrix-Assisted Pulsed Laser Evaporation (MAPLE), enabling controlled surface functionalization. Following thermal treatment, the formation of the crystalline magnesium pyrophosphate (Mg₂P₂O₇) phase was confirmed by chemical and structural characterization. The combination of a slowly degrading PCL matrix, providing sustained structural support, and a bioactive MgP coating, enabling rapid and controlled ion release, results in improved scaffold performance in terms of biocompatibility, biodegradability, and bioactivity. While the slow degradation rate of PCL ensures mechanical stability over an extended period, the surface-deposited MgP phase allows immediate interaction with the biological environment, facilitating faster ion release and enhancing cell–material interactions. These findings highlight the potential of the developed composites as promising candidates for trabecular bone regeneration and as viable alternatives to conventional CaP-based scaffolds in regenerative medicine. Full article

Licania tomentosa leaf extract was used to synthesize zinc oxide nanoparticles (ZnO NPs) which were systematically analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Visible (UV-Vis) and Fourier transform infrared (FT-IR) spectroscopies and energy-dispersion X-ray spectroscopy (EDS) methods. Based on XRD scans, the green NPs have an average crystallite size of 15.9 nm as estimated using the Scherrer equation and have a roughly spherical shape with an average diameter of 25.15 ± 1.2 nm as calculated from SEM data. As estimated from the Tauc plot based on UV-Vis absorption spectra, ZnO NPs have a small band gap of 3.0 eV. The biosynthesized ZnO NPs were effectively utilized for the photodegradation of methylene blue (MB) and crystal violet (CV) dyes under UV illumination with resulting MB and CV degradation efficiencies of ~94% and ~81% after 60 min and 70 min, with pH = 12 and pH = 10, respectively. Different experimental parameters such as NPs quantity, experimental pH, light intensity and initial concentration of dyes were varied to test the performance of the catalyst. Furthermore, efficient recycling of the catalyst was demonstrated. We also undertook antimicrobial studies of the green ZnO NPs. The ZnO NPs demonstrated broad-spectrum antimicrobial efficacy against Escherichia coli ATCC 35218, Enterococcus faecalis ATCC 29737, Klebsiella pneumoniae ATCC 700603, Pseudomonas aeruginosa ATCC 27853, P. aeruginosa B3, Staphylococcus aureus ATCC 29213, and S. aureus SA01, with the minimum inhibitory concentration (MIC) and the inhibitory concentrations associated with 50% effect (IC50) values ranging from 250 to 2000 µg/mL and 7.74 to 283.14 µg/mL, respectively. The nanoparticles also significantly inhibited biofilm formation by E. faecalis ATCC 29737, P. aeruginosa ATCC 27856, and S. aureus SA03. The antimicrobial efficiency of the ZnO NPs against Escherichia coli ATCC 25922 and Staphylococcus aureus SA03 isolates was also assessed using the disk diffusion assays. Taken together, our results reveal that the biosynthesized ZnO NPs are promising multifunctional materials with potential applications in antimicrobial treatments, biofilm control, and photocatalytic remediation. Full article

Surface discharge-induced degradation poses a significant threat to the operational reliability of high-voltage insulation systems. This research investigates the dielectric endurance of polyester-based nanocomposites reinforced with seven distinct nano-additives: iron oxide (Fe₃O₄), copper oxide (CuO), titanium oxide (TiO₂), aluminum oxide (Al₂O₃), silicon dioxide (SiO₂), zinc borate (ZnB) and graphene oxide (GO). Specimens were fabricated at 0.5% and 0.75% weight concentrations and subjected to constant AC electrical stress of 4.5 kV at 50 Hz until failure using the first-plane tracking method. To accurately monitor the aging process, a sophisticated signal processing framework involving Hankel-matrix-enhanced Robust Principal Component Analysis (RPCA) was developed to extract high-frequency discharge features from captured leakage current signals. The degradation characteristics were quantified using various statistical metrics, including Kurtosis, RMS and Burst Discharge Index (BDI). Experimental findings demonstrate that the incorporation of nanoparticles significantly extends the time-to-failure compared to neat polyester, although the effectiveness is highly dependent on both additive type and concentration. At 0.5 wt.%, ZnB exhibited the superior performance in delaying carbonized track formation. However, at 0.75 wt.%, Al₂O₃ emerged as the most effective additive, achieving a maximum endurance time of 31.61 min. In contrast, certain additives like TiO₂ showed a performance decline at higher loadings, likely due to nanoparticle agglomeration. The Hankel-RPCA methodology successfully isolated discharge-specific signatures from background noise, establishing a strong correlation between signal features and material failure stages. This study confirms that the synergy between advanced nanomaterial modification and robust signal processing provides an effective diagnostic tool for monitoring insulation health, offering a vital pathway for the designing of high-performance dielectrics for real-world power system applications. Full article

Aqueous redox flow batteries (ARFBs) are a promising solution for large-scale energy storage; however, the development of organic posolytes that combine high redox potential with long-term stability remains a significant hurdle. This study introduces sodium 3-(10H-phenoxazin-10-yl)propane-1-sulfonate (POZS), a novel sulfonate-functionalized phenoxazine derivative designed to overcome these limitations. By incorporating hydrophilic anionic sulfonic groups, this molecular engineering strategy enhances the structural stability of redox-active phenoxazine materials. Although POZS shows limited solubility in pure water, its solubility increases to 0.98 M (equivalent to a charge capacity of 26.3 Ah L⁻¹) upon the addition of 1.5 M tetraethylammonium chloride (TEAC). This enhancement suggests that the supporting electrolyte optimizes the ionic environment and mitigates intermolecular aggregation, thereby facilitating higher active species concentration. Electrochemical characterization of POZS reveals a highly positive redox potential of 1.51 V (vs. Zn/Zn²⁺) and rapid electron transfer kinetics (2.02 × 10⁻² cm s⁻¹). When tested in a zinc-based hybrid flow cell, the POZS posolyte demonstrates excellent rate capability (up to 50 mA cm⁻²) and a temporal capacity fade rate of 0.335% per hour over 500 cycles—a nearly five-fold improvement over previously reported quaternized phenoxazines. Post-cycling analyses indicate that while the phenoxazine core remains susceptible to nucleophilic ring substitution, the pendant sulfonate groups ensure that any resulting byproducts remain soluble, preventing the catastrophic depletion typically caused by the precipitation of degraded active species. These findings establish a robust molecular framework for the design of high-potential, durable organic posolytes for sustainable energy storage systems. Full article

Biodegradable zinc (Zn) has attracted increasing interest as a material for temporary implants, primarily due to its moderate degradation kinetics. In recent years, additive manufacturing of Zn alloys using the laser powder bed fusion method (L-PBF) has shown promising results. Compared to as-cast Zn alloys, it offers preferable customized solutions for patient-specific temporary biomedical implants. Due to the novelty of these printed degradable biomaterials and due to reported cytotoxic effects of Zn alloys, this study investigates additively manufactured ZnAgCu, ZnAgCuMn, and ZnAgCuTi alloys, both in as-printed and post-processed conditions, with a focus on L929 and SAOS-2 biocompatibility. In this work, we demonstrate that the increased porosity and therefore larger surface areas compared to polished Zn-alloy samples affect their biocompatibility. Minimal to no cell proliferation was observed on and near the Zn-alloy test plates after 24 h. Undiluted extracts from as-cast Zn and L-PBF-manufactured plates were initially cytotoxic to SAOS-2 cells. However, as passivation proceeded, cytocompatibility was significantly increased from day 3 onward. Zn²⁺ ion release peaked at 24 h and declined significantly from day 2 to day 10. Compared to the other Zn alloys, ZnAgCuMn exhibited the lowest cytocompatibility. Most intriguingly, 3-month surfaces exhibited reduced cytocompatibility to osteoblasts compared to freshly polished samples. The observed in vitro cytotoxicity motivates further investigation of as-printed and post-processed L-PBF-manufactured Zn alloys, aiming to develop novel surface modification strategies to mitigate the initial ion burst responsible for reduced cytocompatibility and to adjust and tailor the overall degradation kinetics to physiologically tolerable levels tailored to the intended clinical application. Full article

The adaptive nature of bacteria and their increasing resistance to conventional therapies demand alternative strategies to effectively control wound infections. At the wound site, dynamic biological processes are easily disrupted by microbial colonization, compromising normal healing. In this study, Zn-based nanoparticles composed of zinc oxide (ZnO) and zinc phosphate (Zn₃(PO₄)₂) were synthesized via a green route using coconut milk and coconut water as biological media. Although ZnO formation via zinc hydroxide intermediates was initially targeted, structural analyses revealed a multiphase Zn-based system resulting from interactions between Zn²⁺ ions and naturally occurring phosphate species in the coconut-derived sources. The resulting material was incorporated into sodium alginate/poly(vinyl alcohol) hydrogel dressings, further enhanced with spirulina and aronia powders. Physicochemical characterization (XRD, SEM, EDS, FTIR), along with swelling and degradation studies, confirmed structural stability and appropriate hydrogel behavior. Antimicrobial testing against Staphylococcus aureus and Escherichia coli demonstrated a dominant antibiofilm effect of the Zn-based nanoparticles, while botanical additives exhibited moderate, time-dependent activity. Biological evaluation demonstrated good cytocompatibility toward human keratinocytes and murine macrophages, with botanical additives mitigating mild nanoparticle-induced cellular responses. Full article

Growing concerns about environmental pollution and the sustainability of conventional nanomaterial synthesis have accelerated interest in plant-based routes for nanoparticle production. This review provides an in-depth analysis of more than 290 peer-reviewed research and review articles published between 2010 and 2025, extracted from the Web of Science and Scopus databases, on the green synthesis of metallic and metal oxide nanoparticles using plant extracts, with particular emphasis on their characterization and application in water treatment. Plant-derived phytochemicals serve as natural reducing and stabilizing agents, enabling nanoparticle formation without hazardous reagents. Key physicochemical characterization techniques, including UV–Visible spectroscopy, X-ray diffraction, Fourier Transform Infrared spectroscopy, scanning and transmission electron microscopy, and energy-dispersive X-ray analysis, are evaluated for their roles in confirming nanoparticle structure, morphology, surface chemistry, and optical behavior. The review focuses on water purification applications, highlighting adsorption and photocatalytic degradation as the most extensively investigated removal pathways. Particular attention is given to widely studied material classes such as silver, zinc oxide, titanium dioxide, and iron-based nanoparticles, which demonstrate effective removal of heavy metals, synthetic dyes, pesticides, and pharmaceutical residues. Current limitations related to synthesis reproducibility, mechanistic understanding, stability, and scalability are critically discussed. The review concludes by identifying priority research directions, including standardized synthesis protocols, deeper chemical analysis of plant extracts, and the integration of green nanoparticles into immobilized and membrane-based systems to advance their practical implementation in sustainable water treatment technologies. Full article

Given the increasing environmental degradation, this study investigates advanced zinc oxide (ZnO)-based materials for the mineralization of toxic compounds through the combined action of photo- and piezocatalysis. Two complementary strategies were employed to enhance catalytic efficiency. First, ZnO_1−xN_x thin films were deposited by reactive high-power impulse magnetron sputtering (R-HiPIMS) to reduce the band gap energy. Second, flower-like ZnO nanostructures were synthesized using the pulsed thermionic vacuum arc (p-TVA) technique to increase the specific surface area. Both systems were further modified by decoration with Ag₂O nanoparticles to improve charge separation. The R-HiPIMS technique offers significant advantages in terms of precise control over processing parameters, enabling accurate tuning of film properties, including microstructure, chemical composition, and electronic structure. However, films produced via R-HiPIMS generally exhibit lower photo-piezocatalytic activity compared to nanostructured counterparts, primarily due to their comparatively reduced effective surface area and limited charge separation efficiency. In contrast, the p-TVA technique enables the synthesis of nanostructured thin films with substantially enhanced photo-piezocatalytic performance. This improvement is attributed to the increased effective surface area and the promotion of more efficient electron–hole pair separation. The materials were comprehensively characterized in terms of optical properties (UV–Vis spectroscopy), chemical composition and bonding (XPS), crystalline structure (XRD), surface morphology (FE-SEM), and photo-piezocatalytic performance. Catalytic activity was evaluated via the degradation of methylene blue (MB) under visible light irradiation and mechanical vibrations. Nitrogen incorporation in ZnO_1−xN_x thin films led to an increase in photocatalytic efficiency from 20% to 28.7%, while the simultaneous application of light and mechanical stimulation increased efficiency to approximately 50%. Under identical irradiation conditions, Ag₂O-decorated ZnO and Ag₂O-decorated ZnO_1−xN_x exhibited photo-degradation reaction rate constants up to 65% higher than bare counterparts, attributed to reduced electron–hole recombination. ZnO nanostructures achieved degradation efficiencies of 59%, rising to 88.3% with Ag₂O decoration under solar illumination for 120 min. When combined with mechanical vibrations, after 60 min, the degradation efficiencies reached 93% for ZnO and 98% for Ag₂O/ZnO systems. A photodegradation mechanism of Ag₂O NPs-decorated ZnO heterostructures was proposed. Full article