Search Results (1,075)

This study investigates the valorization of dredged sludge as a sustainable subgrade fill material through stabilization with a nano-calcium carbonate–cement composite. Unconfined compressive strength (UCS) tests were systematically conducted to determine the optimal dosage of nano-CaCO₃ as a supplementary additive at a fixed cement content of 8% by dry soil mass. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and quantitative pore structure analysis were employed to elucidate the underlying solidification mechanisms. The results demonstrate that the addition of 2% nano-CaCO₃ yields the highest 28-day UCS of 721 kPa, representing a statistically significant 21% improvement over the cement-only reference (596 kPa) and a more than threefold increase relative to untreated sludge (213 kPa). Conversely, increasing the nano-CaCO₃ dosage to 2.5% leads to a significant strength reduction, attributed to nanoparticle agglomeration and hindered cement hydration. Microstructural characterization reveals that the optimal nano-CaCO₃ dosage accelerates early-age hydration through a nucleation effect, promotes the consumption of portlandite, and enhances the formation of calcium silicate hydrate (C–S–H) gel. Semi-quantitative XRD analysis further confirms the conversion of less stable monosulfate (AFm-SO₄) into stable monocarboaluminate (AFm-CO₃) phases. These synergistic mechanisms—nucleation, physical pore filling, and chemical reaction—result in a densified matrix with a refined pore structure, reduced total porosity, and a more homogeneous pore-size distribution. The findings provide a robust theoretical basis for the resource-oriented utilization of dredged sludge and the design of low-carbon composite stabilizers for soft soil treatment. Full article

The peripheries of rare-metal metallogenic systems frequently host skarn-type or hydrothermal vein-type Pb-Zn deposits, though their genetic connections with parental systems remain debated. The newly identified Gariatong W-Mo polymetallic metallogenic system in the Lhasa Terrane displays well-defined Nb-Ta-Rb, Mo-W, W-Mo, W-Bi, and Pb-Zn-Ag metallogenic zoning, establishing it as an exemplary site for investigating genetic relationships between Pb-Zn and rare-metal mineralization. This investigation targets skarn-type Pb-Zn deposits spatially associated with rare-metal orebodies at Gariatong, utilizing integrated analytical approaches, including in situ LA-ICP-MS trace-element analysis of sulfides, sulfur isotope geochemistry, and LA-ICP-MS elemental mapping of sphalerite, to constrain metal sources, characterize fluid evolution, and establish genetic correlations with the rare-metal system. Key findings include the following: (1) sphalerite shows enrichment in Fe, Mn, Co, and Cd, while pyrite contains elevated As, Pb, Co, Cu, and Mn. Fe, Cd, and Mn primarily occur as solid solutions or nanoparticles, whereas As and Pb exist as micro-inclusions. (2) Sphalerite Zn/Cd ratios (73.6–184) and Co-Ni-As ternary diagrams confirm a magmatic–hydrothermal skarn origin. (3) Mineralization occurred under moderate-temperature, mildly oxidized conditions, as constrained by sphalerite Fe contents and mineral assemblages. Sulfur isotope compositions (δ³⁴S = −1.0‰ to 3.2‰; mean: 1.9‰) indicate a magmatic sulfur source. This study reveals that the Nb-Ta-Rb mineralization, quartz-vein- and greisen-type W-Mo deposits, and skarn-type Pb-Zn orebodies—all genetically associated with highly fractionated granites—constitute an integrated magmatic–hydrothermal system with vertical (depth-related) zoning relative to the granitic intrusion. These results provide critical constraints for understanding rare-metal–Pb-Zn genetic associations and suggest that Pb-Zn mineralization may serve as a key exploration indicator for rare metals in the Lhasa Terrane. Full article

Despite the growing adoption of Ti6Al4V-ELI made by Laser Powder Bed Fusion (LPBF) in tribologically demanding applications, the influence of hybrid nanoparticle additives on its lubrication behavior under starved contact conditions remains insufficiently explored. The tribological performance of Ti6Al4V was investigated under starved boundary-to-mixed lubrication conditions using engine oil modified with Ag-doped TiO₂ nanoparticles. Double-scan LPBF-fabricated discs were tested in a ball-on-disc configuration against AISI 52100 bearing steel using a TRB³ tribometer. Nanolubricants were prepared by dispersing TiO₂ and Ag–TiO₂ nanopowders with different Ag⁺/Ti⁴⁺ ratios (0.5%, 1.5%, and 2.5%) in SAE 10W-40 engine oil at a constant nanoparticle concentration of 0.05 wt%. Comprehensive physicochemical characterization of the nanopowders and nanolubricants was performed through structural, chemical, optical, morphological, rheological, and stability analyses. Tribological experiments were conducted following a full-factorial design combining three normal loads (5–15 N), three sliding speeds (0.10–0.20 m·s⁻¹), and four lubricant formulations. The steady-state coefficient of friction ranged between 0.281 and 0.359, while the specific wear rate varied from 2.81 × 10⁻⁴ to 4.83 × 10⁻⁴ mm³·N⁻¹·m⁻¹. The contact temperature rise remained relatively moderate, within the interval of 1.9–9.4 °C. Among the investigated formulations, the lubricant containing 1.5% Ag–TiO₂ exhibited the lowest friction coefficient, whereas the formulation with the highest Ag content showed improved stability of tribological performance across the investigated operating domain. These results indicate that Ag-modified TiO₂ nanoparticles are consistent with the formation of protective tribofilms and contribute to the stabilization of friction, wear, and thermal behavior under starved lubrication conditions. ANOVA confirmed that sliding speed and the load–lubricant interaction are the dominant factors governing friction and wear, while normal load controls the thermal response. These findings support the use of Ag–TiO₂ nanolubricants as a viable strategy for stabilizing interfacial behavior in LPBF-fabricated titanium components operating under starved lubrication conditions. Full article

This study explored the eco-friendly synthesis of AgNPs using Prosopis laevigata seed mucilage and assessed their antimicrobial, antibiofilm, and biocompatibility effects against foodborne pathogens. The AgNPs were mostly spherical, with sizes ranging from 2.5 to 56 nm (average: 14.69 nm), as confirmed by XRD and DLS analysis. They showed consistent antimicrobial activity, with MICs at 0.5 mg/mL and MBCs at 1.0 mg/mL across all tested strains, and inhibited bacterial growth by over 75% at 0.5–5 mg/mL, similar to or better than gentamicin. The antibiofilm performance was notable, with inhibitions of 76–84% against E. coli (1–10 mg/mL), 96–98% against S. aureus (0.5–10 mg/mL), 76–82% against Salmonella Typhimurium (0.5–10 mg/mL), and 70–84% against P. aeruginosa (1–10 mg/mL), surpassing gentamicin against E. coli and P. aeruginosa. Cell viability remained 100% at 0.25 mg/mL, and no significant changes in immunological parameters were observed, suggesting good biocompatibility at therapeutic doses. This research shows, for the first time, that P. laevigata mucilage is an effective bioreducing agent for green synthesis of AgNPs with antimicrobial and antibiofilm activity against both Gram-negative and Gram-positive foodborne pathogens. Its superior ability to inhibit biofilms compared to traditional antibiotics, along with its safety profile at therapeutic levels, makes these nanoparticles promising for food safety applications, antimicrobial coatings, and topical treatments. Overall, the findings support the use of native plant resources in green nanotechnology to address global challenges of antimicrobial resistance. Full article

Contamination of water resources by organic pollutants is a major environmental issue. Utilizing photocatalytic materials for the degradation of these pollutants presents a viable strategy for environmental clean-up. This study introduces the synthesis of an organic/inorganic hybrid photocatalyst of β-cyclodextrin (β-CD)/reduced graphene oxide (rGO) and titanium oxide (TiO₂) nanoparticles. The nanocomposite was characterized by using FT-IR, XRD, SEM, and EDAX, and the photocatalytic activity was studied by measuring the photodegradation of methylene blue (MB) under simulated solar radiation. The synthesized nanocomposite showed excellent stability and performance, with up to 92% photodegradation of MB. To further enhance the photocatalytic activity, the synthesized nanocomposite underwent modification with Ag and Pt nanoparticles. Within 90 min, photodegradation rates of 100% and 97% for MB were attained with Pt and Ag nanoparticles that were loaded at 5 wt.%, respectively. The photocatalyst’s reusability was evaluated through multiple usage cycles. Additionally, the impact of functionalization on the band gap alteration of TiO₂ is reported. Full article

Although teixobactin, a promising cyclic undecadepsipeptide, exhibits efficacy against Gram-positive bacteria due to its novel mode of action and low potential for resistance, its clinical application is limited by two key shortcomings: ineffectiveness against Gram-negative bacteria and poor penetration of the protective extracellular polymeric substance (EPS) in biofilms. This renders it unsuitable for targeting the polymicrobial biofilms, which are the cause of periodontitis and peri-implantitis. We designed a modified teixobactin analog by integrating rhamnolipid, Ag@Fe₃O₄ nanoparticles, and _L-Chg₁₀-teixobactin to obtain a novel magnetic nanoparticle (MNP). The MNP demonstrates the ability to simultaneously degrade EPS, penetrate biofilm structures, and eliminate both G⁺ and G⁻ pathogens under a rotating magnetic field (RMF). Rhamnolipid grafting degraded 52.5% of biofilm EPS. MNPs showed broad-spectrum antimicrobial activity, with minimal inhibitory concentrations from 100 to 200 µg/mL. Combined with RMF, biofilm eradication rates reached 97.0% (E. faecalis), 97.7% (S. gordonii), 88.4% (P. gingivalis), and 74.2% (F. nucleatum). The biofilm thickness was reduced from 19.4 ± 2.9 µm to 7.4 ± 1.0 µm, and the biofilm biomass was reduced by 68.5%. This combined strategy integrates enzymatic EPS degradation, magneto-mechanical disruption, and dual antimicrobial action, offering a promising topical therapy for periodontitis and peri-implantitis. Full article

Naked oat (Avena nuda L.) is an important dual-purpose crop for grain and forage in cold regions; however, its high fatty acid content renders seeds prone to deterioration during storage. This study aimed to investigate the protective effects of zinc oxide nanoparticles (ZnO NPs) on artificially aged naked oat seeds and elucidate the underlying molecular mechanisms. Non-aged seeds (Naged) were subjected to artificial aging at 45 °C and 100% relative humidity for 24 h (Aged), followed by priming with 30 mg L⁻¹ ZnO NPs for 6 h (Daged). Antioxidant enzyme activities were determined spectrophotometrically, and transcriptome sequencing was performed on an Illumina platform to identify differentially expressed genes (DEGs) and enriched pathways. We found that ZnO NPs increased catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD) activities by 3–4-fold, restored germination rate from 75% to 98%, and enhanced seed vigor index. A total of 21,403 DEGs were detected, with 15,841 stably expressed in response to nano-priming. Reactive oxygen species (ROS) burst rapidly induced up-regulation of AP2/EREBP transcription factor family members, which subsequently activated antioxidant enzyme genes to maintain cellular redox homeostasis. Metabolic pathway analysis demonstrated that the phenylpropanoid pathway was reprogrammed, characterized by down-regulated lignin biosynthesis and up-regulated flavonoid production, thereby enhancing ROS scavenging capacity. Additionally, the pentose phosphate pathway was activated to provide additional NADPH for antioxidant defense, and up-regulated ADP-glucose pyrophosphorylase (AGPase) facilitated starch accumulation. Notably, the 40S ribosomal protein S13 exhibited the highest connectivity in protein–protein interaction networks, was up-regulated 2.1-fold, and was enriched in post-translational modification processes. These findings suggest that nano-priming with ZnO NPs represents a promising biotechnological strategy for enhancing seed vigor and storability in naked oat, with potential applications in sustainable agriculture and the seed industry. Full article

Objective: The objective of this study is to evaluate the ability of silver oxide nanoparticle (Ag₂ONP)-functionalized high-efficiency particulate air (HEPA) filters and colloidal Ag₂ONP suspensions to inhibit biofilm formation by major respiratory pathogens causing infections at operating rooms. Background: Respiratory infections caused by bacterial pathogens such as Streptococcus pneumoniae, Pseudomonas aeruginosa and Staphylococcus species are often associated with the formation of biofilms, which confer increased resistance to antibiotics and host immune responses. Effective strategies to prevent biofilm formation on biological surfaces and in air filtration systems are urgently needed in clinical settings. Methods: The biofilm-forming ability of each bacterial strain was assessed by crystal violet microplate assay, viable count or confocal microscopy after prior incubation of the culture medium with Ag₂ONP-coated HEPA filter material or colloidal Ag₂ONP suspension. Results: Both silver-functionalized filters and silver nanoparticle suspensions significantly inhibited biofilm formation by S. pneumoniae and P. aeruginosa, with near-complete suppression observed. In the case of S. aureus and S. epidermidis, the silver nanoparticle suspension showed partial inhibition of biofilm development. Conclusions: Ag₂ONP-functionalized HEPA filters and colloidal Ag₂ONP suspensions effectively prevent biofilm formation by major respiratory pathogens, for both Gram-negative and Gram-positive bacteria. These materials show promise for integration with air filtration and surface coating systems to reduce microbial load and transmission in healthcare environments such as operating room facilities. Full article

Green-synthesized silver nanoparticles (AgNPs) exhibit outstanding antibacterial and antioxidant potential for designing and developing nanomedicines and medical devices. Nephelium lappaceum or rambutan contains polyphenol-based phytochemicals, which suggests its suitability for the green synthesis of NPs. However, the lack of a systematic approach directly impacts the robustness and reproducibility of the process. Design of experiments can address these challenges in obtaining NPs with the desired quality profile. In this work, we demonstrated the advantages of a Plackett–Burman model in the semi-automated green synthesis of AgNPs using N. lappaceum peel extract. The extract concentration was the only significant factor affecting the particle size. The optimized NPs exhibited triangular and hexagonal morphologies and a hydrodynamic diameter of 80 nm after 24 h without a stabilizing agent, representing 1.2% prediction error according to the model’s equation. The in vitro antioxidant capacity was confirmed through the ABTS radical scavenging assay. The AgNPs displayed a minimum inhibitory concentration of 23.5 µg mL⁻¹ against Escherichia coli and Staphylococcus aureus. Overall, this work highlights the synergistic role between a DoE-assisted green synthesis, the phytochemicals from N. lappaceum peel extract, and the formed AgNPs, positioning this systematic approach as a sustainable and efficient process for novel antibacterial and antioxidant agents. Full article

Fiber-reinforced polymer (FRP) composites used in marine environments suffer progressive degradation due to hydrothermal aging, which undermines their structural, physical and morphological integrity. In this study, a novel polyester-based nano-gelcoat reinforced with hexagonal boron nitride (h-BN) nanoparticles was developed as an advanced FRP composite coating for marine applications. Glass fiber/epoxy laminates coated with h-BN/polyester nano-gelcoat were subjected to accelerated hydrothermal aging (immersion in 80 °C artificial seawater for 90 days). Mechanical (tensile/flexural tests), viscoelastic (creep and stress relaxation), thermal (DSC/TGA), and morphological (optical microscopy/SEM) analyses were performed on aged and unaged samples. The h-BN-enhanced nano-gelcoat increased the composite’s resistance to hydrothermal aging. In particular, the optimally doped nano-gelcoat (~1 wt% h-BN) retained the highest tensile and flexural strength and modulus, reducing the property losses seen in the unreinforced system by about half (flexural strength 531.29 MPa vs. 1070.52 MPa for the uncoated laminate). Thermal analysis indicated elevated decomposition onset temperatures and higher char yields with h-BN, confirming improved thermal stability. Morphological observations revealed well-dispersed h-BN at 1 wt% with minimal microcracking, whereas higher filler loadings led to agglomeration. Additionally, a TOPSIS-based multi-criteria decision-making (MCDM) analysis was performed across mechanical, viscoelastic, and thermal metrics, which identified the 1 wt% h-BN coating as the most balanced formulation after hydrothermal aging. Full article

Silver nanoparticles (AgNPs) are among the most widely used type of nanoparticles due to their antimicrobial properties. While their application in disease treatment is well established, less is known about their ecological effects after they are released into ecosystems, where they may affect microorganisms and disrupt ecological balance. A green synthesis using Sambucus nigra fruit extract was applied to prepare AgNPs of two sizes, and their interactions with Brevundimonas vesicularis USM1, Pseudarthrobacter oxydans USM2, Pseudomonas putida USM4, Escherichia coli ATCC 10536, Staphylococcus aureus ATCC 25923, and Pseudomonas aeruginosa ATCC 27853 were examined. The nanoparticles were characterized by UV–Vis, TEM, and DLS, and microbial growth was assessed using microplate assays and colony enumeration. No significant inhibition of E. coli ATCC 10536, S. aureus ATCC 25923, or P. aeruginosa ATCC 27853 was observed in the presence of small (22 nm) or large (66 nm) AgNPs. Growth inhibition occurred in P. oxydans USM2 and P. putida USM4 exposed to small AgNPs, and in B. vesicularis USM1, P. oxydans USM2, and P. putida USM4 exposed to large AgNPs. The strain-specific responses indicate a size-dependent impact on bacteria, suggesting potential effects on microbiome structure and function. This study provides insights supporting environmental risk evaluation and safer-by-design development of AgNP-based materials. Full article

Cutaneous wound healing is a complex biological process often impaired by bacterial infections, especially by Staphylococcus aureus. To address this, alginate (ALG)/chitosan (CS) polyelectrolyte multilayer (PEM) films incorporating alginate-coated silver nanoparticles (ALG–AgNPs) were fabricated by layer-by-layer self-assembly. The films exhibited a porous, layered morphology with homogeneous distribution of ALG–AgNPs, hydrophilic surfaces (contact angle ≈ 55°), a high swelling degree (~175%), and a water vapor transmission rate of 1830 g m⁻²·day⁻¹. Thermal analyses showed similar degradation profiles up to 600 °C, with the ALG–AgNP film displaying lower moisture loss and higher dehydration temperature, consistent with enhanced ionic and coordination crosslinking (–NH₃⁺/–COO⁻ and Ag–O–C bonds). The release of Ag⁺ in PBS (pH 7.4) was ~3% after 24 h, following a Korsmeyer–Peppas mechanism (R² = 0.97, n < 0.5), and degradation, with ~40% mass loss in 6 days, indicated gradual matrix disintegration. Cytocompatibility studies revealed >80% viability for fibroblasts, keratinocytes, macrophages, and <2% hemolysis of red blood cells. Immune assays showed a tendency towards reduced TNF-α and IL-1β and regulated IL-6/IL-8 release. Antibacterial evaluations demonstrated a 5-log reduction in planktonic bacterial viability and >2-log reduction in adhesion, and an 11 ± 1 mm inhibition zone for S. aureus. These results demonstrate that ALG/CS–AgNP PEM films combine biocompatibility, antibacterial efficacy, controlled degradation, and structural stability, making them promising multifunctional scaffolds for the regeneration of infected skin wounds. Full article

Postprandial hyperglycemia represents a critical therapeutic target in type 2 diabetes mellitus (T2DM), requiring interventions that simultaneously address glycemic dysregulation and oxidative stress. This study evaluated the anti-hyperglycemic and antioxidant properties of Sclerocarya birrea leaf crude extract (CE) and biosynthesized silver nanoparticles (AgNPs). Phytochemical screening, nanoparticle characterization (UV–Vis, XRD, TEM, SEM, DLS, FTIR), enzyme inhibition assays (α-amylase, α-glucosidase, DPP-IV), glucose dynamics in Caco-2 cells, and antioxidant assays (DPPH, total antioxidant capacity, H₂O₂ cytoprotection) were performed. Phytochemical analysis identified flavonoids, tannins, alkaloids, and terpenoids as major constituents of Sclerocarya birrea leaf extract. AgNPs exhibited spherical morphology (36.8 ± 8.6 nm, n = 100 particles analyzed), face-centered cubic crystallinity (crystallite size: 32.1 nm), and characteristic surface plasmon resonance at 451 nm. Both formulations inhibited α-amylase (CE IC₅₀: 14 µg/mL; AgNPs IC₅₀: 14.07 µg/mL, n = 3) and α-glucosidase (CE IC₅₀: 15.96 µg/mL; AgNPs IC₅₀: 15.82 µg/mL, n = 3), showing substantial inhibition, though less potent than acarbose. Uniquely, AgNPs demonstrated selective DPP-IV inhibition (IC₅₀: 220.5 µg/mL, n = 3, p < 0.001 vs. CE), completely absent in CE. In antioxidant assays, DPPH scavenging potency was comparable between formulations (CE IC₅₀: 23.45 µg/mL; AgNPs IC₅₀: 22.26 µg/mL, n = 3), while CE achieved higher maximal scavenging at the tested concentrations. Conversely, AgNPs provided superior intracellular cytoprotection against H₂O₂-induced oxidative stress in kidney cells (80.2 ± 2.1% viability at 76 µg/mL vs. CE 69.8 ± 3.4% at 190 µg/mL, n = 3, p < 0.001), representing a 2.5-fold dose advantage. Neither formulation significantly altered glucose uptake or SGLT1 expression in intestinal epithelial cells (p > 0.05, two-way ANOVA, n = 3). These findings establish S. birrea-based formulations, particularly AgNPs, as promising multifunctional candidates for managing postprandial hyperglycemia and oxidative complications in T2DM. They also highlight nanotechnology-enhanced phytomedicine as an innovative therapeutic strategy. Full article

Reliable detection of microplastics by surface-enhanced Raman scattering (SERS) is often hindered by poor particle–substrate contact and limited access to plasmonic hotspots on conventional planar substrates optimized for molecular adsorption. Here, we report a rapid microwave-assisted carbothermal shock strategy to fabricate silver nanoparticle-decorated electrospun carbon fibers (AgNPs@ECF) as a three-dimensional plasmonic platform tailored for solid microplastic sensing. Localized microwave-induced heating in a mixed ethanol–hexane system enables Ag nanoparticle nucleation and anchoring on conductive carbon fibers within 45 s, yielding a mechanically compliant, junction-rich architecture without chemical reductants or vacuum processing. The AgNPs@ECF composite was evaluated using morphologically weathered polystyrene (PS) and polyethylene terephthalate (PET) microplastics, along with size-controlled PS bead standards ranging from ~50 nm to 45 μm. Across these models, SERS response is governed primarily by particle–substrate contact geometry and near-field accessibility rather than polymer type. The strongest enhancement occurs in the sub-micrometer regime, where particles can engage multiple AgNP-decorated fiber junctions, while ultrasmall and large, smooth particles show reduced enhancement due to limited contact or rapid field decay. Spatially resolved Raman mapping and finite-difference time-domain simulations support a contact-dominated enhancement mechanism, revealing localized field confinement at particle–fiber interfaces. These results establish the design principles for three-dimensional SERS substrates targeting heterogeneous solid particulates, demonstrating that contact-accessible plasmonic architectures are critical for reliable microplastic detection under realistic solid-particle measurement conditions. Full article

This study presents a straightforward process for producing a hybrid ternary composite of silver nanoparticles (Ag NPs), small graphene oxide (s-GO), and zirconia (ZrO₂) and its use as an electrode material for electrochemical sensing. The physico-chemical properties of the ternary composite were analyzed by means of field emission scanning electron microscopy (FE-SEM), ultraviolet-visible (UV-vis) and FTIR spectroscopy, X-ray Photoelectron Spectrometry (XPS) and contact angle (CA) measurements. The synthesized hybrid nanomaterial was employed as an electrode modifier in the fabrication of a modified screen-printed carbon electrode (SPCE) and used for the simultaneous electrochemical sensing of key environmental pollutants such as hydroquinone (HQ) and catechol (CAT). The developed sensor exhibited linearity in the range of 0–100 µM for both HQ and CAT, with sensitivity values of 2640 µA·mM⁻¹·cm⁻² for HQ and 5120 µA·mM⁻¹·cm⁻² for CAT. The limits of detection (LOD) were 1.5 µM for HQ and 0.72 µM for CAT, respectively. The synergistic enhancement of electron transfer kinetics, the increased electroactive surface area, the strong anti-interference capability, and excellent reproducibility and stability establish these modified electrodes as promising candidates for environmental monitoring and real sample analysis. Full article