Search Results (1,698)

We demonstrate that pulsed laser annealing induces plasmonic gold nanoparticles in ZnO thin films, monitored in real-time via pulse-by-pulse spectroscopy. Initially embedded gold nanoparticles (smaller than 5 nm) in sputtered ZnO films were annealed using 532 nm pulses from a Q-switched Nd:YAG laser while monitoring transmission spectra in situ. A plasmonic resonance dip emerged after ~100 pulses in the 530–550 nm region, progressively deepening with continued exposure. Remarkably, different incident energies converged to a thermodynamically stable optical state centered near 555 nm, indicating robust nanoparticle configurations. After several hundred laser shots, the process stabilized, producing larger nanoparticles (40–200 nm diameter) with significant surface protrusion. SEM analysis confirmed substantial gold nanoparticle growth. Theoretical modeling supports these observations, correlating spectral evolution with particle size and embedding depth. The protruding gold nanoparticles can be functionalized to detect specific biomolecules, offering significant advantages for biosensing applications. This approach offers superior spatial selectivity and real-time process monitoring compared to conventional thermal annealing, with potential for optimizing uniform nanoparticle distributions with pronounced plasmonic resonances for biosensing applications. Full article

Wetlands are delicate ecosystems that host diverse species and face ongoing environmental stress. The “Carlos Anwandter” Ramsar Site in Valdivia, Chile, is the world’s main breeding ground for the black-necked swan, which strongly relies on the aquatic plant Egeria densa. This area has been impacted by anthropogenic activities that have increased particulate iron (Fe) and zinc (Zn) deposition. However, standard protocols for metal analysis encourage eliminating any particles on the plant’s surface, neglecting the contribution of deposited particulate contaminants. Appropriate sample treatment is therefore essential to quantify metal concentrations and the potential impact on herbivore species. This study aimed to evaluate how sample treatments and plant sectioning affect Fe and Zn concentrations in E. densa. Samples were collected from both the Ramsar site (Cruces River) and a control site (Calle-Calle River). Results showed that washing samples (both in the field and lab) significantly reduced reported metal concentrations, underscoring the importance of standardised sampling and pre-treatment protocols. Fe concentrations were notably higher at the Ramsar site (11,155 mg kg⁻¹) compared to the control (3783 mg kg⁻¹). The same is true for Zn (108 mg kg⁻¹ and 60 mg kg⁻¹, respectively). Over time, Fe concentrations remained stable, while Zn concentrations declined, suggesting a consistent Fe input and a decreasing Zn trend in the wetland. These findings are crucial for interpreting metal pollution and understanding spatial–temporal variability in aquatic plant contamination. Full article

This study investigates the impact of tire wear particles (TWPs) and their dissolved organic matter (DOM) on soil DOM dynamics and heavy metal behavior. Through short-term incubation experiments under simulated natural conditions with TWPs of varying particle sizes, we analyzed ecological changes in soil. Using three-dimensional excitation–emission matrix (3D-EEM) spectroscopy coupled with parallel factor analysis, we monitored the photochemical properties and compositional evolution of soil dissolved organic matter. Results demonstrate that TWP amendment substantially alters soil DOM molecular characteristics, inducing a sharp decrease in protein-, carbohydrate-, and lipid-like components, the degradation of low-aromaticity unstable dissolved organic matter, and an overall increase in aromaticity. Furthermore, TWP input directly modified soil properties, triggering the transformation of soil aggregates: the proportion of large aggregates significantly decreased while that of small aggregates increased, thereby reducing overall aggregate stability. The bioaccessibility of heavy metals (HMs) (Cd, Cu, and Zn) extracted by CaCl₂ increased, primarily due to the release of endogenous metals from TWPs, compounded by the disruption of soil aggregates. In contrast, Pb tended to transform into more stable fractions under TWP stress, reducing its bioaccessibility. Further correlation analysis indicated that TWPs indirectly affected HM (Cd, Cu, and Zn) fractionation by influencing the soil dissolved organic matter properties and soil properties. This study provides a new perspective for elucidating the interplay between dissolved organic matter and HMs in urban soils, as mediated by tire wear particles (TWPs). Full article

Efficient synthesis routes for zinc oxide nanoparticles (ZnO NPs) that are rapid and non-toxic and operate at room temperature (RT) are essential to expand accessibility, minimize environmental impact, and enable integration with temperature-sensitive substrates. In this work, ZnO NPs were synthesized by probe ultrasonication at RT for durations from 30 s to 10 min and benchmarked against our previously reported water bath sonication method. A 10-min probe treatment yielded highly uniform ZnO NPs with particle sizes of 60–550 nm and a specific surface area of up to 75 m² g⁻¹, compared to ~38 m² g⁻¹ for bath sonication. These features were largely preserved after calcination at 500 °C. When integrated into chemiresistive devices, the resulting ZnO (P(10))-based sensors exhibited pronounced selectivity toward styrene, showing reversible responses at low concentrations (10–50 ppm) and stronger signals at higher levels (up to 200 ppm, with resistance changes reaching 2930%). The sensors demonstrated stable operation across 10–90% relative humidity, and consistent performance from −20 °C to 180 °C. Flexibility tests confirmed reliable sensing after 100 bending cycles at 30°. Overall, RT-probe ultrasonication offers a rapid, scalable, and eco-friendly route to ZnO NPs with tunable properties, opening new opportunities for flexible gas sensing. Full article

This study systematically optimizes the T6 heat treatment of a commercial EV31A magnesium alloy and evaluates the resulting microstructural evolution and mechanical properties. Optical microscopy, scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to characterize the microstructure and phase constitution, while differential scanning calorimetry (DSC) was employed to determine appropriate solution treatment parameters. Brinell hardness measurements and tensile tests at room temperature and 150 °C were carried out to quantify the mechanical response. The as-cast alloy consists of α-Mg equiaxed grains, bone-shaped Mg₁₂(Nd,Gd) eutectic phases at grain boundaries, and minor intragranular lath-shaped Mg₁₂Nd phases. After T6 treatment (520 °C/10 h solution treatment + 200 °C/16 h aging), the grain boundary eutectic phases partially dissolve and transform into Mg₄₁(Nd,Gd)₅, while intragranular nano-scale β′ precipitates and stable Zn₂Zr₃ particles form, achieving multi-scale synergistic strengthening. Compared to the as-cast condition, the T6-treated alloy exhibits room-temperature ultimate tensile strength and yield strength of 309 ± 40.5 MPa (31% increase) and 180 ± 14.2MPa (45% increase), respectively. At 150 °C, the strength reaches 241 ± 7.5 MPa (39% increase) and 154 ± 16.8 MPa (52% increase), while maintaining an elongation of 10.9± 0.7%, demonstrating an excellent strength–ductility balance. Full article

Fungal infections caused by Fusarium solani demand sustainable alternatives to conventional fungicides and free nanoparticles, which often show poor stability and rapid release. This study developed zinc-crosslinked alginate microparticles containing silver (AgNPs), zinc oxide (ZnONPs), or both to improve nanoparticle stability, sustain release, and enhance antifungal efficacy. Microparticles were produced by ionic gelation and characterized by FTIR, microscopy, swelling analysis, encapsulation efficiency, and kinetic modeling. AgNPs weakened hydrogen bonding within alginate, yielding rough, porous structures, whereas ZnONPs strengthened COO⁻–Zn²⁺ interactions, forming smoother surfaces with smaller pores; co-loaded particles combined both characteristics. Encapsulation efficiencies were 77.9% (AgNPs) and 98.6% (ZnONPs), with co-loaded systems retaining 64.0% and 98.9%, respectively. Swelling was highest in AgNP-loaded microparticles (63.8%) and lowest in ZnONP and co-loaded systems (≈42%). AgNPs followed anomalous transport (n = 0.65), while ZnONPs transitioned from Fickian diffusion (n ≈ 0.36–0.38) to zero-order release (K₀ = 1.00 for ZnONPs alone; 0.80 co-loaded). Antifungal tests showed strong inhibition: 80.7% for AgNPs, 91.4% for ZnONPs, and 99.7% for co-loaded formulations. Microscopy confirmed membrane disruption, hyphal collapse, and ROS-mediated damage, with the strongest effects in co-loaded samples. These results demonstrate a tunable, synergistic, sustained-release platform that outperforms single nanoparticles and offers a promising strategy for sustainable crop protection. Full article

Al–Zn–Ca alloys are good candidates for industrial electronics and electric vehicles due to their high thermal conductivity, castability, and corrosion resistance, but their strength requires improvement. This study investigates how Sc and Zr additions affect the microstructure, thermal, mechanical, and corrosion properties of an Al–3 wt% Zn–3 wt% Ca base alloy. Microstructural analysis showed that substituting Sc with Zr did not drastically alter the phase composition but changed the elemental distribution: Sc was uniform, while Zr segregated to center of dendritic cell. Zr addition also refined the grain size from 488 to 338 μm. An optimal aging treatment at 300 °C for 3 h was established, which enhanced hardness for all alloys via precipitation of Al₃Sc/Al₃(Sc,Zr) particles. However, this Zr substitution reduced thermal conductivity (from 184.7 to 168.0 W/mK) and ultimate tensile strength (from 269 to 206 MPa), though it improved elongation at fracture (from 4.6 to 7.1%). All aged alloys exhibited high corrosion resistance in 5.7% NaCl + 0.3% H₂O₂ water solution, with Zr-containing variants showing a lower corrosion rate and better pitting resistance. The study confirms the potential of tuning Sc/Zr ratios in Al–Zn–Ca alloys to achieve a favorable balance of strength, ductility, thermal conductivity, and corrosion resistance. Full article

This paper presents the preparation and characterization of single-mode optical fibers coated with zinc oxide (ZnO) nanoparticles using the immersion technique. The study was carried out in three stages: the first consisted of pretreating the fiber by means of controlled immersion in HCl and H₂SO₄ solutions and exposure in a muffle furnace; the second involved the growth and deposition of ZnO nanoparticles synthesized in a laboratory; and the third was characterization by means of atomic force microscopy (AFM). In this last stage, we obtained through AFM that Sample 1, considered optimized, presented high particle density (9.203 particles/µm²), an RMS roughness (Rq) of 2.98 nm, and average roughness (Ra) of 1.82 nm, as well as an average height of 1.117 nm. These parameters reflect a uniform and stable surface, desirable conditions for applications in the development of high-sensitivity optical sensors and biosensors. Full article

Cu₂ZnSnSe₄ is a promising light-absorbing material for cost-effective and eco-friendly thin-film solar cells; however, its synthesis often leads to secondary phases that limit device efficiency. To overcome these challenges, we devised a straightforward and efficient method to obtain single-phase Cu₂ZnSnSe₄ nanocrystalline powders directly from the elements Cu, Zn, Sn, and Se via mechanochemical synthesis followed by vacuum annealing at 450 °C. Phase evolution monitored by X-ray diffraction (XRD) and Raman spectroscopy at two-hour milling intervals confirmed the formation of phase-pure kesterite Cu₂ZnSnSe₄ and enabled tracking of transient secondary phases. Raman spectra revealed the characteristic A₁ vibrational modes of the kesterite structure, while XRD peaks and Rietveld refinement (χ² ~ 1) validated single-phase formation with crystallite sizes of 10–15 nm and dislocation densities of 3.00–3.20 10¹⁵ lines/m². Optical analysis showed a direct bandgap of ~1.1 eV, and estimated linear and nonlinear optical constants validate its potential for photovoltaic applications. Scanning electron microscopy (SEM) analysis showed uniformly distributed particles 50–60 nm, and energy dispersive X-ray (EDS) analysis confirmed a near-stoichiometric Cu:Zn:Sn:Se ratio of 2:1:1:4. X-ray photoelectron spectroscopy (XPS) identified the expected oxidation states (Cu⁺, Zn²⁺, Sn⁴⁺, and Se²⁻). Electrical characterization revealed p-type conductivity with a mobility (μ) of 2.09 cm²/Vs, sheet resistance (ρ) of 4.87 Ω cm, and carrier concentrations of 1.23 × 10¹⁹ cm⁻³. Galvanostatic charge–discharge testing (GCD) demonstrated an energy density of 2.872 Wh/kg⁻¹ and a power density of 1083 W kg⁻¹, highlighting the material’s additional potential for energy storage applications. Full article

Rare-earth oxide (REO) nanoparticles (NPs)—such as cerium (CeO₂), samarium (Sm₂O₃), neodymium (Nd₂O₃), terbium (Tb₄O₇), and praseodymium (Pr₂O₃)—have demonstrated strong antimicrobial activity against multidrug-resistant bacteria. Their effectiveness is attributed to unique physicochemical properties, including oxygen vacancies and redox cycling, which facilitate the generation of reactive oxygen species (ROS) that damage microbial membranes and biomolecules. Additionally, electrostatic interactions with microbial surfaces and sustained ion release contribute to membrane disruption and long-term antimicrobial effects. REOs also inhibit bacterial enzymes, DNA, and protein synthesis, providing broad-spectrum activity against Gram-positive, Gram-negative, and fungal pathogens. However, dose-dependent cytotoxicity to mammalian cells—primarily due to excessive ROS generation—and nanoparticle aggregation in biological media remain challenges. Surface functionalization with polymers, peptides, or metal dopants (e.g., Ag, Zn, and Cu) can mitigate cytotoxicity and enhance selectivity. Scalable and sustainable synthesis remains a challenge due to high synthesis costs and scalability issues in industrial production. Green and biogenic routes using plant or microbial extracts can produce REOs at lower cost and with improved safety. Advanced continuous flow and microwave-assisted synthesis offer improved particle uniformity and production yields. Biomedical applications include antimicrobial coatings, wound dressings, and hybrid nanozyme systems for oxidative disinfection. However, comprehensive and intensive toxicological evaluations, along with regulatory frameworks, are required before clinical deployment. Full article

To investigate the effect of nanoparticle reinforcement, polymer blends (M8) comprising polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, and chitosan were modified using zinc oxide particles (M8/ZnO). This study introduces an M8-modified ZnO composite that offers a non-antibiotic approach relevant to antimicrobial resistance. The average particle size of the ZnO particles was determined to be 181.8 nm using scanning electron microscope (SEM) analysis. Based on the inhibition percentage, M8 has a minimum inhibition concentration (MIC) to have at least a 50% inhibition, or MIC50 value, against Pseudomonas aeruginosa (PA) and Salmonella enterica (SE) at 12.5 and 25% of M8, respectively. The MIC with at least a 90% inhibition percentage, or MIC90, of M8 against SE and PA is 25% of M8. On the other hand, the MIC50 of M8/ZnO against SE, Staphylococcus aureus (SA), and PA is 25, 12.5, and 50% of M8/ZnO, respectively. The MIC90 of M8/ZnO against SE and SA is 50% and 25% of M8/ZnO, respectively. However, M8/ZnO does not inhibit a minimum of 90% of the PA bacteria. Hence, the ratio optimization between M8 and ZnO or the usage of other particles should be considered as a topic for future study. Full article

This research focuses on the investigation of microstructure, deformation, and superplastic behavior in wide range of strain rates of novel crossover Al-Zn-Mg-Cu alloy with Y/Er. The precipitation and superplastic behavior of the Al-Zn-Mg-Cu-Zr-Cr-Ti with Er/Y and Fe/Si impurities alloys have been studied. The microstructure of the alloys with nano-sized precipitates and micron-sized particles allows obtaining a micrograin stable microstructure. The spherical D0₂₃-Al₃(Er,Zr) precipitates with a diameter of about 20 nm and rod-like crystalline and qusicrystalline E (Al₁₈Mg₃Cr₂) precipitates with a thickness of about 20 nm and length of about 150–200 nm were identified by transmission electron microscopy. The superplastic deformation behaviors were investigated under different temperatures of 460–520 °C and different strain rates of 3 × 10⁻⁴ to 3 × 10⁻³ s⁻¹. The microstructure observation shows that uniform and equiaxed grains can be obtained by dynamic recrystallization before superplastic deformation. The alloy with Y exhibits inferior superplastic properties, while the alloy with Er has an elongation of more than 350% at a rate of 1 × 10⁻³ s⁻¹ and a temperature of 510 °C. Full article

The influence of synthesis method on the properties of Zn_1−xFe_xO nanoparticles with different Fe doping levels (x = 0, 0.01, 0.03, and 0.05) for Congo Red (CR) adsorption was investigated. Nanoparticles were prepared by sol–gel and coprecipitation and characterized by XRD, SEM-EDS, FTIR, and BET analyses. Sol–gel synthesis produced smaller particles (~13 nm) than coprecipitation (~35 nm), and both the method and calcination temperature strongly affected crystallite size. Sol–gel nanoparticles showed significantly higher adsorption efficiency (~90%) due to their larger BET surface area, greater BJH pore volume, and smaller particle size, which increased the number of accessible active sites. In contrast, coprecipitation nanoparticles exhibited a much lower adsorption capacity (~24%). Fe incorporation further enhanced performance by introducing lattice distortions and oxygen vacancies, as evidenced by XRD peak broadening and increased lattice strain. SEM images displayed particle growth and compaction after adsorption, particularly in doped samples. Temperature-dependent experiments indicated that undoped ZnO lost efficiency at 60 °C due to weak physical interactions, whereas Fe-doped nanoparticles maintained high adsorption, due to improved stability of the adsorbent-adsorbate bond. The combination of Fe doping and sol–gel synthesis significantly improved the properties of ZnO, yielding highly efficient adsorbents suitable for environmental remediation. Full article

Zinc oxide (ZnO) nanoparticles are widely used in cosmetics, coatings, and industrial formulations due to their UV-absorbing and antimicrobial properties; however, their increasing release into aquatic systems has raised concerns about potential ecological risks. This study evaluates the acute toxicity of pure and silver-doped ZnO (Ag-ZnO) nanoparticles using Artemia salina as a marine model organism. Nanoparticles were synthesized via a reflux-assisted method and characterized by UV–Vis spectroscopy, HRTEM, ED, FTIR, and EDX analyses, confirming a crystalline wurtzite structure, particle sizes of 10–30 nm, and successful incorporation of 5% Ag. Silver doping produced a slight blue shift in the absorption edge and minor lattice distortions, indicating modifications in the electronic structure. Toxicity assays revealed clear concentration- and time-dependent decreases in nauplii survival. Dose–response modeling showed LC₅₀ values of 358 ppm (24 h) and 64 ppm (48 h) for pure ZnO, whereas Ag-ZnO exhibited LC₅₀ values of 607 ppm (24 h) and 28 ppm (48 h). These results indicate that Ag doping does not enhance short-term toxicity but markedly increases toxicity after prolonged exposure. Overall, the findings highlight the need to consider both nanomaterial composition and exposure duration in ecotoxicological assessments and provide relevant data for evaluating the environmental impact of doped nanomaterials in marine systems. Full article

The impact of zinc oxide (ZnO) nanoparticles on the dispersion, rheological behaviour, and mechanical properties of epoxy-based composites was investigated. Through experimental examinations, we found that 100 nm ZnO with a 4 wt.% content, when incorporated into epoxy, demonstrated homogeneous dispersion. Conversely, an increase in ZnO nanoparticle content led to particle agglomeration within the composite’s core. Rheology tests revealed that the 4 wt.% ZnO/epoxy mixture exhibited the lowest shear stress value, surpassing even the neat epoxy. Additionally, theoretical models were employed to evaluate the stress–strain properties of the ZnO/epoxy with the hollow glass fibre composite system. The study demonstrates the critical role of ZnO nanoparticle content in achieving dispersion and mechanical strength without the need for chemical solvents or surface modifications. Furthermore, variations in ZnO content within the composite resulted in a differing Young’s Modulus and UV absorbability, highlighting the importance of nanoparticle concentration in determining material properties. The study also delves into the effects of core diameter, length of hollow glass fibres (HGF), and adhesive layer thickness on stress transfer and strain deformation mechanisms within the composite system. Full article