Search Results (19,650)

The aim of this study was to investigate the effect of PEG functionalization of hydrothermal carbon (HTC) on quercetin adsorption and desorption kinetics and, through that, evaluate the potential of functionalized HTC as a carrier for quercetin. Hydrothermal carbon (HTC) was synthesized using fructose as a precursor at a temperature of 160 °C. Structural and morphological analyses using X-ray diffraction and scanning electron microscopy (SEM) confirmed an amorphous carbon structure and microspherical particles with an average size of 5.6 µm. X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared (FT-IR) spectroscopy characterization revealed a surface enriched with hydroxyl and carboxyl groups, which facilitated successful PEG modification. Surface modification was further corroborated by a zeta potential shift from –26.4 mV to –16.4 mV. Cytotoxicity assays in MRC-5 and HeLa cell lines confirmed high biocompatibility, with cell viability remaining above 70%. Quercetin binding experiments showed that PEG functionalization increased binding capacity up to 14%, reaching 19.50 mg/g for PEG-functionalized fructose-derived carbon. Desorption kinetics followed a pseudo-second-order model, with the PEG-modified sample exhibiting significantly slower rates than the unmodified sample. These findings indicate that PEG functionalization can improve the adsorption/desorption properties of HTC compared with the pristine material, highlighting its potential as a promising, environmentally friendly, and efficient delivery system for quercetin. Full article

Climate-related and environmental hazards affect cultural heritage sites in markedly different inland, coastal, lacustrine and underwater settings, creating documentation requirements that cannot be addressed by a single sensing approach. This study presents the multi-sensor geometric documentation of eight cultural heritage sites. Unmanned aerial vehicle (UAV) photogrammetry was applied to six inland and coastal sites, while underwater photogrammetry, unmanned surface vehicles (USVs), acoustic sounding and a prototype green-wavelength flash LiDAR were used at three shallow-water sites. The campaigns produced orthomosaics, elevation models, dense point clouds, textured meshes, bathymetric maps and underwater LiDAR point clouds at scales appropriate to the conservation problem of each site. The resulting products document exposed architectural remains, excavation areas, cliffs and unstable slopes, lake-margin changes, submerged masonry, wooden structures and lakebed morphology. Their main contribution is the establishment of spatially explicit, site-specific baselines that provide measurable geometric and visual evidence for condition assessment, future repeat-survey comparisons and the spatial integration of environmental, archaeological and conservation information. The study demonstrates the operational and information complementarity of optical, acoustic and active ranging approaches, which address different documentation scales, environmental constraints and heritage targets, and provide distinct spatial evidence that can serve as potential inputs to subsequent digital twin and decision support applications. Full article

To mitigate the deterioration of the tribological performance of end-face friction pairs under low-speed conditions, this study investigated a water-lubricated CF/PEEK–316L stainless steel end-face friction pair. Surface micro-textures with different depth-to-diameter ratios and texture area ratios were fabricated on the 316L stainless steel surface to evaluate the effects of texture parameters and sliding speed on tribological performance. The results showed that appropriately designed micro-textures effectively reduced the coefficient of friction and improved the wear characteristics of the friction pair. Among the tested conditions, the CF/PEEK–316L stainless-steel tribo-pair with a 316L counterface textured at ε = 0.05 and s = 10% exhibited the lowest average friction coefficient. At 200 rpm, this textured tribo-pair exhibited an average friction coefficient approximately 34.8% lower than that of the untextured tribo-pair. Furthermore, laser micro-textures suppressed interfacial material transfer and mitigated adhesive wear and three-body abrasive wear by capturing wear debris. Gear-pump prototype tests further showed that the textured surface improved flow-delivery and volumetric-efficiency performance, while promoting more uniform end-face wear morphology, indicating its potential application in practical gear-pump components. The findings provide guidance for surface-texture design and tribological-performance optimization of polymer/metal end-face friction pairs. Full article

In the present study, the potential applications of Cu thin films and Ag/Cu bilayer thin films obtained by the pulsed laser deposition (PLD) technique are investigated in terms of the physicochemical effects resulting from their interaction with an aqueous solution containing Reactive Blue 21 (RB21) dye and sodium bicarbonate (NaHCO₃). The thin-film deposition process was carried out using a Q-switched Nd:YAG laser system operating at a wavelength of λ = 532 nm, with a pulse duration of τ = 10 ns, a repetition rate of ν = 10 Hz, a pulse energy of E = 180 mJ, a laser spot diameter of d = 336 μm, and an angle of incidence of α = 45°. Two types of thin films were prepared: a Cu thin film and an Ag/Cu bilayer thin film. The thermal effects induced by the interaction of the laser beam with the target materials were investigated by numerical simulations performed in COMSOL, allowing the evaluation of melt-phase formation for each material separately and providing a better understanding of the morphology and topography of the deposited thin films. The simulation results were validated through scanning electron microscopy (SEM) observations and surface roughness analyses. The two thin films were subsequently treated with an aqueous solution containing 10 g/L RB21 dye and 10 g/L NaHCO₃. Physicochemical analyses performed after treatment, including scanning electron microscopy (SEM), optical microscopy (OM), profilometry, Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), X-ray Photoelectron Spectroscopy (XPS) and UV–Vis spectroscopy, revealed significant degradation of the RB21 dye accompanied by corrosion of the thin films, with the corrosion process being more pronounced in the case of the Cu thin film. The obtained results indicate that the method analyzed in this study may represent an alternative approach for the decomposition of recalcitrant organic dyes using thin Cu films, without relying on conventional photocatalytic processes. Equally important are the potential applications of the RB21/NaHCO₃ solution as an etching and patterning medium for thin Cu layers, while the Ag overlayer may provide a protective effect during such processes. These findings may contribute to the development of novel fabrication techniques for optoelectronic components, including solar cells, photovoltaic windows, and other industrial and laboratory applications. Full article

Background and Objectives: Magnesium-based biomaterials are increasingly investigated due to their biodegradability, bone-like elastic modulus, and potential osteogenic properties. However, alloy composition may influence degradation behavior and local tissue response. This study aimed to assess and compare the local biocompatibility, degradation characteristics, and bone regenerative response induced by Mg-Zn-Mn-Ca and Mg-Nd-Y-Zr-Zn magnesium alloy powders. Materials and Methods: Two magnesium alloys were evaluated through physicochemical characterization, in vitro osteoblast cytocompatibility and antimicrobial assays, and in vivo testing in Sprague–Dawley rats. Standardized cylindrical defects were created in the medial femoral condyle and filled with either Mg-Nd-Y-Zr-Zn or Mg-Zn-Mn-Ca alloy powders, while untreated defects served as controls. Bone remodeling and defect healing were assessed by micro-computed tomography, allowing three-dimensional qualitative and quantitative evaluation of newly formed bone. Scanning electron microscopy was used to analyze surface morphology and degradation features, while histopathological examination assessed inflammation, osteogenesis, and tissue integration at the implant site. Results: Both magnesium alloy powders showed antimicrobial potency and elicited no cytotoxic effects in vitro, while animal studies revealed progressive biodegradation over time, associated with new bone formation within and around the defect area. Micro-CT analysis demonstrated active bone remodeling in experimental groups, with differences in bone distribution and defect-filling patterns between Mg-Nd-Y-Zr-Zn and Mg-Zn-Mn-Ca implants. SEM revealed alloy-specific degradation morphologies. Histological evaluation showed a moderate early inflammatory response that decreased at later time points, together with ongoing osteogenesis and favorable tissue integration. No severe local adverse reactions or persistent inflammation were observed. Conclusions: Both Mg-Nd-Y-Zr-Zn and Mg-Zn-Mn-Ca alloy powders were locally biocompatible and supported bone regeneration in a rat femoral condyle defect model. Differences in degradation behavior and tissue response emphasize the relevance of alloy composition in developing magnesium-based biomaterials for bone defect treatment. Full article

This study developed an oleic acid (OA)-functionalized, bio-derived calcium carbonate (Bio-CaCO₃) filler recovered from Asian green mussel (Perna viridis) shell waste for incorporation into a hydroxypropyl methylcellulose (HPMC)-glycerol (Gro) matrix as a hydrophobic composite coating for reducing pesticide deposition on mandarin surfaces. Aragonite-rich Bio-CaCO₃ was extracted through a combined chemical treatment and mechanical pulverization process. The extracted Bio-CaCO₃ was characterized by scanning electron microscopy, X-ray diffraction, laser diffraction, and ATR FT-IR spectroscopy. At the optimal OA concentration, surface functionalization yielded OA-functionalized Bio-CaCO₃ (OA-Bio-CaCO₃) powder beds that exhibited apparent superhydrophobicity; successful functionalization was confirmed by X-ray photoelectron spectroscopy. The resulting HPMC-Gro-OA-Bio-CaCO₃ coating dispersion (CD-OA) formed hydrophobic composite films (f-CD-OA), as demonstrated by water contact-angle measurements and surface-morphology analysis. The CD-OA coating formulation was successfully applied to mandarin surfaces by a dip-coating process. Colorimetric screening indicated that organophosphate pesticide residues on coated mandarins did not exceed hazardous levels, even at 20 times the manufacturer-recommended application rate. Quantitative LC-MS/MS and GC-MS/MS analyses demonstrated that the optimized CD-OA coating formulation provided substantial short-term protection against acetamiprid and chlorothalonil with pesticide-deposition reductions of 89% and ≥96%, respectively, after 1 d relative to pristine mandarins. These findings advance the functional reuse of biogenic CaCO₃ and offer a simple, water-based dip-coating approach that provides temporary surface protection for citrus production and food-safety management. Full article

Background/Objectives: Morphological signs of non-carious tooth surface loss are clinically heterogeneous, and their prevalence depends strongly on the diagnostic framework and threshold used. This exploratory secondary analysis evaluated a study-specific combined morphological outcome restricted to second permanent molars and its association with cumulative caries experience in a regional clinical sample of adolescents. Methods: The analysis included 231 adolescents aged 13–19 years from Dolj, Gorj, and Olt counties, selected from a parent clinical database of 638 participants. The study-specific outcome was coded when a clearly discernible non-carious hard-tissue change compatible with an abrasive, erosive, or abfraction-related morphology was identified on any clinically accessible surface of tooth 17, 27, 37, or 47. This study did not use BEWE, the Smith and Knight Tooth Wear Index, or another validated severity-based tooth wear index; subtype, surface, and severity were not retained separately in the analytical dataset. Dental caries experience was measured using DMF-T. Group comparisons, correlations, and multivariable logistic regression were performed in JASP version 0.96.0. Sensitivity analyses included a participant-level coding audit and a logistic model using DMF-T recalculated after excluding the contribution of teeth 17, 27, 37, and 47. Results: The study-specific morphological outcome was present in 50/231 participants (21.6%). A coding audit confirmed that 181 participants had no positive second molar and 50 had exactly one positive second molar; tooth-specific counts were 14, 15, 12, and 9 for teeth 17, 27, 37, and 47, respectively. In the primary model, male sex (adjusted OR = 3.34, 95% CI 1.67–6.71) and DMF-T (adjusted OR = 1.15 per point, 95% CI 1.01–1.31) were associated with the outcome. After excluding the four evaluated second molars from DMF-T, the caries experience association remained positive but borderline (OR = 1.198, 95% CI 1.000–1.435, p = 0.049), while male sex remained associated (OR = 3.310, 95% CI 1.647–6.652, p < 0.001). Conclusions: A modest exploratory association was observed between the study-specific morphological outcome and cumulative caries experience in this clinical sample. The result should not be interpreted as a standardized NCDL prevalence estimate, a causal relationship, or a prediction model. Confirmation using validated whole-mouth tooth wear measures, outcome-specific reliability assessment, and population-based longitudinal data is required. Full article

Ammonium dinitramide (ADN) is a high-energy green oxidizer with significant potential for use in solid propellants; however, its practical application is restricted by its strong hygroscopicity and low safety. In this study, morphology control and surface coating were simultaneously addressed by preparing ADN/PVA composite particles with different PVA contents by membrane emulsification. At a PVA content of 5%, the ADN/PVA composite microspheres exhibited favorable morphology and a high degree of sphericity, with no phase transition induced and the crystal structure well preserved. DSC results showed that the initial decomposition temperature of ADN/PVA increased by 21.88–26.50 °C compared to that of raw ADN, and the exothermic peak became narrower, indicating that the energy release of ADN was more concentrated and its thermal stability was significantly improved. Meanwhile, the impact sensitivity and friction sensitivity were reduced by 33.33% and 16.67%, respectively, relative to raw ADN, and the moisture absorption rate was reduced by 87.92%. Therefore, the ADN/PVA composite particles prepared by membrane emulsification exhibit excellent thermal stability and anti-hygroscopicity. Full article

Significant research efforts have recently focused on nanomaterial processing for gas sensors and related sensing applications. However, the major challenges in the field involve the choice of material for the sensing layer of the sensor device element, together with the right structure, assembly, and morphology through which the full sensing properties of the material can be realised. Herein, we critically review the hierarchical nanostructures of V₂O₅ nanomaterial for application in gas sensing technology. Beyond the sheet structure, which serves as the fundamental building block of the V₂O₅’smolecular arrangement, nanostructures ranging from nanobelts to nanowires, nanorods, nanoribbons, nanofibres, nanotubes, and thin films were discovered as preferred configurations and thermodynamically favourable structures, according to many synthesis processes. Ethanol (C₂H₅OH) and Nitrogen dioxide (NO₂) gases were identified as preferred molecules commonly detected by various V₂O₅ morphologies, with the nanotube structure showing preferential sensitivity and selectivity to C₂H₅OH. We also discuss perspectives from density functional theory (DFT) studies of V₂O₅ nanostructures and other (2D) materials structures for gas sensing applications. The studies highlight enhanced adsorption energy, increase conductivity, and band gap variation as a result of an upper shift in the Fermi level, all as a consequence of surface interaction between semiconductor crystal orientation and chemical molecules. Finally, our calculations of the optimised parameters for α-V₂O₅ orthorhombic structure showed good agreement with experimental and other theoretical data in the literature. The adsorption energy profile for NO₂ molecules revealed that the Ag-doped surface exhibits the most negative adsorption energy compared with the clean surface and other doped surfaces. Full article

This work investigated the extraction behavior of Zn, Cu, and Fe during sulfuric acid leaching of metallurgical waste from the Ust-Kamenogorsk zinc production plant. At the same time, the detailed kinetic analysis was restricted to Zn dissolution. This study aimed to determine the structural and morphological characteristics of metallurgical wastes and the extraction efficiencies of Zn, Cu, and Fe, and to evaluate the apparent kinetics of Zn dissolution comparatively. The phase composition of the initial and mechanically treated samples was studied by X-ray diffraction analysis, functional groups by FTIR spectroscopy, and morphological features by scanning electron microscopy. Leaching experiments were conducted to assess the effect of sulfuric acid concentration, temperature, and process duration. The results showed that mechanical treatment produced qualitative morphological and structural changes in the slag and was accompanied by improved extraction of Zn, Cu, and Fe during sulfuric acid leaching. The extraction behavior depended on the experimental variable investigated. In the sulfuric acid concentration series, extraction from the mechanically treated sample reached 70.55 ± 0.88% for Zn, 90.50 ± 0.47% for Cu, and 42.37 ± 0.47% for Fe at 1.0 M H₂SO₄. In the leaching time series conducted at 1.0 M H₂SO₄ and 75 °C, Zn extraction reached 78.06 ± 0.92% at 120 min after mechanical treatment, whereas Cu extraction reached its maximum of 90.78 ± 0.55% at 60 min. The time-dependent extraction behavior differed among the investigated metals, and no single leaching time maximized Zn, Cu, and Fe extraction simultaneously. Comparative analysis using Shrinking Core Model expressions indicated that both surface-reaction and product-layer-diffusion expressions provided comparable descriptions of the Zn leaching data; however, the limited number of kinetic data points does not allow definitive identification of a unique rate-controlling mechanism. For Zn dissolution, the apparent activation energies were 8.16 and 10.17 kJ mol⁻¹ for the surface chemical reaction expression and 14.37 and 17.81 kJ mol⁻¹ for the product-layer diffusion expression before and after mechanical treatment, respectively. A conceptual leaching pathway based on the available experimental observations was proposed to relate the observed structural and morphological changes to Zn extraction and the formation of a gypsum-containing solid residue. The results indicate that mechanical treatment is a promising pretreatment approach for improving the hydrometallurgical processing of the investigated metallurgical waste under the tested conditions. Full article

Background: The optical losses in the form of reflections, parasitic absorption, and scattering limit photovoltaic efficiency. This review examines plasma-assisted surface engineering as an effective tool for improving light management in solar cells. Plasma-based methods, including etching, oxidation, deposition, and texturing, enable precise control of surface morphology and chemistry, lowering reflectance, enhancing light trapping, and passivating defects. Methods: In contrast to wet-chemical or high-temperature processes, plasma processes are dry, low-temperature, scalable, and can be used with silicon, perovskite, thin-film, and organic solar cells, as well as tandem structures. The fundamentals of optical losses are described, along with the principles of radio-frequency (RF), inductively coupled plasma (ICP), microwave, and atmospheric plasma systems and their distinctive advantages for controlling ion and reactive-species generation. Key applications reviewed include black-silicon texturing by ICP reactive-ion etching (ICP-RIE), anti-reflective/passivation coatings by plasma-enhanced chemical vapor deposition (PECVD), and interface activation by atmospheric plasma. Results: Among performance improvements are a reflectance of less than 2%, a photocurrent increase of 10–20%, and longer carrier lifetime. Conclusions: The advantages of plasma compared to lithography and sol–gel processes are in the precision and affordability of the method. The difficulties include damage caused by the processing, uniformity over extensive areas, and environmental stress resistance. Future directions rely on low-temperature plasmas for flexible PV, machine-learning-guided process optimization, and hybrid plasma–laser systems. This synthesis of otherwise fragmented studies is intended to support the implementation of plasma-based methods in next-generation, high-efficiency, and sustainable solar production. Full article

Surfactants are widely used to promote hydrate formation and improve flow assurance, yet their effects on hydrate surface morphology at the microscale remain poorly understood. Here, in situ Atomic Force Microscopy (AFM) was employed to quantitatively characterize the surface microstructure of tetrahydrofuran (THF) hydrate formed in the presence of five distinct surfactants, with particular emphasis on grain area, protrusion distribution, grain-boundary geometry, and surface roughness. Results show that pure THF hydrate exhibits a relatively smooth and regular grain morphology, with narrow and shallow grain boundaries and only limited protrusions. Surfactant addition induces pronounced surface reconstruction, yet the morphological evolution pathways differed markedly among systems. Surfactants I and II were associated with grain refinement, reducing the average grain area to 71.4 and 89.9 μm², respectively, while protrusions were concentrated mainly near grain boundaries and grain-boundary grooves became deeper, corresponding to a grain-boundary-dominated roughening mode. In contrast, surfactants III–V were associated with grain coarsening, increasing the average grain area to 121.1, 128.2, and 156.0 μm², respectively, together with more pronounced intragranular protrusions and widened grain boundaries, corresponding to an intragranular-dominated roughening mode. All surfactants increase surface roughness of THF hydrate to different extents. These findings reveal that surfactants regulate hydrate surface architecture through site-selective adsorption, offering a mechanistic framework for the molecular design of surfactant additives in hydrate-based applications. Full article

Background: The development of sustainable biomaterials that combine imaging capability with complementary biological functions without relying on incorporated drugs or exogenous fluorophores represents an attractive strategy for multifunctional biomedical platforms. Methods: Here, carboxymethyl cellulose (CMC) hydrogels reinforced with nanographene oxide (nGO) were developed by citric acid-mediated crosslinking using nGO contents of up to 3% (w/w) and evaluated for their physicochemical, electrochemical, and biological properties. Results: nGO exhibited a nanosheet morphology, a hydrodynamic diameter of 5.0 ± 0.2 nm, and a specific surface area of approximately 650 m² g⁻¹. Incorporation of nGO modified the hydrogel structure and reduced water uptake within the tested formulation window. The nanocomposite hydrogels maintained high cytocompatibility, with approximately 100% HeLa cell viability after 24 h. Confocal microscopy and quantitative fluorescence-intensity analysis demonstrated enhanced fluorescence relative to untreated cells, reaching approximately eightfold higher signal intensity and supporting proof-of-concept fluorescence-assisted visualization of HeLa cells without exogenous fluorescent probes. However, because only HeLa cells were evaluated and no cancer-specific targeting ligand was incorporated, these findings do not establish diagnostic specificity. The CMC–nGO hydrogels also exhibited radical-scavenging activity of up to 96.5% and antimicrobial activity against Escherichia coli and Candida albicans, with maximum inhibition zones of 12.9 and 9.2 mm, respectively. In addition, nGO incorporation modified the electrochemical response of graphite electrodes, supporting the multifunctional character of the platform. Conclusions: Overall, CMC–nGO hydrogels provide a sustainable, drug-free, and fluorophore-free biointerface combining fluorescence-assisted cell visualization with antioxidant, antimicrobial, and electrochemical functionalities. Further photophysical characterization, comparison with non-cancerous cervical cells, rheological and mechanical evaluation, and validation in advanced biological models are required to establish their potential for future bioimaging and biosensing applications. Full article

Building facades and construction materials are continuously exposed to airborne particulate matter, organic pollutants, and microbial colonization, which cause progressive soiling, aesthetic degradation, and structural deterioration while imposing high maintenance and energy burdens. Photocatalytic titanium dioxide (TiO₂) has emerged as the most widely studied material for imparting self-cleaning functionality to building surfaces, owing to its ability to mineralize adsorbed contaminants under solar irradiation and to modulate surface wettability. This narrative review provides a structured account of TiO₂-based self-cleaning coatings for building materials, organized around three complementary themes: surface mechanisms, performance metrics, and outdoor durability. We first rationalize the two intertwined self-cleaning mechanisms—photocatalytic oxidative degradation and photoinduced superhydrophilicity—and their combination with physically repellent (superhydrophobic/superamphiphobic) wetting states. We then survey the principal coating-design strategies, including morphology and facet engineering, SiO₂-TiO₂ composites, metal/non-metal doping and heterojunction construction for visible-light activation, and dual-functional photocatalytic–superhydrophobic systems, and their integration into cementitious substrates, natural stone and cultural heritage, and transparent glass/photovoltaic surfaces. The quantitative metrics used to benchmark self-cleaning performance—water contact angle, dye photodegradation, NO_x and VOC abatement, and antimicrobial activity—are critically discussed together with the limitations of standardized laboratory tests. Finally, we analyze the weathering-induced deactivation pathways (photocatalyst leaching, surface contamination by soluble salts, and UV aging of organic matrices) and the emerging strategies for durable coatings, including inorganic binders, light-driven hydration, and defect- and heterojunction-engineered photocatalysts. The review concludes with an outlook on the open challenges that must be addressed to translate these coatings from laboratory demonstrations to long-lived, large-scale building applications. Full article

Versatile nanostructured materials based on electrochemically etched porous silicon (pSi) are being developed, which have tuneable pore morphology and unique optical and electrochemical properties that enable their effective biosensing applications. It has been shown that fabrication parameters critically influence pore formation and sensor performance, yet challenges remain in reproducible synthesis, structural stability and device integration. Here we review the electrochemical etching synthesis of pSi and recent advances in pSi-based optical and electrochemical biosensors for detecting bacteria, biomolecules, and viruses. We highlight strategies such as surface functionalisation, incorporation of nanomaterials, and integration with microfluidic and lab-on-a-chip technologies that enhance sensitivity and response times by addressing mass transfer limitations. These developments highlight pSi’s potential as a low-cost, adaptable biosensing material with applications in clinical diagnostics and environmental monitoring, while mapping future directions to overcome current fabrication and stability challenges. Full article