Search Results (6,466)

Although natural biopolymers represent promising sustainable packaging alternatives, their weak mechanical and barrier properties limit industrial use. While previous reviews focus on descriptive aspects of enzymatic modification, this review fills a critical literature gap by systematically bridging molecular-level laccase-driven reactions with quantitative techno-economic and safety and regulatory frameworks. We evaluate the kinetic and topological differences between direct tyrosyl-coupled protein homopolymerisation and mediator-assisted ‘graft-then-link’ polysaccharide strategies. Crucially, we analyse how entrapment versus surface-immobilised architectures dictate mass-transfer regimes, establishing their specific functional fitness for active oxygen scavenging or intelligent time-temperature monitoring. Beyond physical performance, we critically assess the translational bottlenecks currently hindering industrial scaling. For the first time, we integrate a quantitative techno-economic analysis using the Technology Readiness Level (TRL) framework, demonstrating that active film fabrication costs (EUR 0.01–0.10/m²) are heavily offset by high-protein food waste savings (>EUR 2.00/kg). Finally, we navigate European and US regulatory landscapes for enzymatically active materials and evaluate safety risks via the Threshold of Toxicological Concern (TTC) model and deterministic migration modelling. This comprehensive analysis establishes a ‘Safe-by-Design’ paradigm, guiding the scalable development of intrinsically safe, high-performance biocatalytic packaging. Full article

The development of sensitive, low–cost, and visually readable dosimeters for low gamma–ray exposures is important for occupational and environmental radiation monitoring and for other low–dose applications. This work investigates a colorimetric and optical thin–film dosimeter based on polyvinyl alcohol (PVA) containing silver nitrate (AgNO₃) and hafnium oxide (HfO₂). The film was fabricated using a solution–casting technique. The dosimetric response was evaluated over an absorbed–dose range of 22.2–65.2 mGy using diffuse reflectance spectroscopy, Kubelka–Munk (K/S) analysis, CIELAB colorimetry, CMYK image–based analysis, and X–ray diffraction (XRD). Irradiation produced a dose–dependent decrease in visible reflectance and a corresponding increase in optical absorption. The K/S response increased with dose, while CIELAB analysis showed a systematic decrease in lightness and an increase in total color difference (${\Delta \mathrm{E}}_{ab}^{\ast }$), reaching approximately 25 at 65.2 mGy. Linear regression of ${\Delta \mathrm{E}}_{ab}^{\ast }$ over 0–65.2 mGy gave y = 0.399x − 1.0029 with R² = 0.9845. CMYK analysis also showed a clear dose response, with the yellow channel (ΔY) exhibiting the largest relative change among the chromatic channels. XRD identified monoclinic HfO₂ as the dominant crystalline filler phase and showed dose–associated changes in peak intensity, peak position, and the relative prominence of the broad PVA–related feature. At the highest XRD dose, several HfO₂ reflections weakened while the broad contribution near 2θ ≈ 19.9–20° became more prominent. These changes are interpreted as dose–dependent structural modification and partial loss of resolved crystalline order rather than definitive evidence of a newly formed crystalline phase. A surface morphology and microstructure analysis was performed on control and γ–ray–irradiated PVA/HfO₂/AgNO₃ nanocomposite films using scanning electron microscopy (SEM–EDX). The morphological transition to fibrous, tree trunk–like structures seen by SEM is well correlated with the dose–dependent change in composition to higher surface Ag content, supporting the idea that radiation–induced Ag nanoparticle nucleation and growth is the primary degradation mechanism in the irradiated films. The combined optical and colorimetric results demonstrate a measurable response of the PVA/HfO₂/AgNO₃ formulation in the investigated low–mGy gamma–ray range. Full article

Waterborne polyurethane (WPU) has emerged as one of the most promising environmentally friendly coating materials owing to its low volatile organic compound (VOC) emissions, excellent film-forming ability, good adhesion, and versatility in formulation. However, WPU suffers from several intrinsic limitations including inadequate thermal stability, modest mechanical strength, poor flame retardancy, and a lack of inherent antibacterial activity. To address these deficiencies, phosphorylated microfibrillated cellulose (PMFC), prepared from beech wood sawdust via sequential steam explosion, phosphorylation, and superfine grinding, was employed as a substrate for in situ silver nanoparticle (AgNPs) synthesis and subsequent incorporation into WPU via aqueous blending and solvent casting. PMFC functions through a combined mechanism: the hydroxyl and phosphate groups coordinate Ag⁺ ions, providing nucleation sites, while the nanofibrillar network provides steric stabilization against post-synthesis aggregation. The influence of AgNPs loading (1–10 wt% relative to PMFC at a fixed 1 wt% PMFC content) on the morphology, antibacterial activity, silver release behavior, thermal stability, flame retardancy, and mechanical properties of the resulting composite films was comprehensively investigated using free-standing composite films as a model system. At the optimal Ag loading of 5 wt%, the composite exhibited strong antibacterial activity against Escherichia coli with silver release below 1.15 ppb after 96 h, while tensile strength and Young’s modulus increased by 80% and 298%, respectively, relative to neat WPU. At high Ag loadings (70–80 wt%), the composites achieved conductive-level surface resistivity (~3 log Ω) through percolation network formation, demonstrating antistatic functionality. This study provides an effective strategy for fabricating WPU composite films with combined antibacterial, mechanical reinforcement, and antistatic capabilities. Full article

Water-based perovskite solar cells (W-PSCs) provide a promising route toward reducing the use of hazardous organic solvents during perovskite fabrication. However, their development remains limited by sluggish precursor conversion, incomplete phase transformation, and poor control over film morphology. This review summarizes recent progress in W-PSCs, with particular emphasis on aqueous lead precursors and the subsequent conversion from precursor films to perovskite absorbers. The selection criteria for aqueous lead sources are first discussed in terms of water solubility, anion-Pb²⁺ interactions, precursor-solution stability, and ion-exchange behavior. Thermodynamic and kinetic considerations, including nucleation, crystal growth, reaction–diffusion coupling, and ion transport, are then discussed to provide a framework for understanding the conversion of aqueous precursor films into perovskites. Strategies for improving film formation are further classified into precursor-film and substrate engineering, conversion-process regulation, and ionic/compositional engineering. Particular attention is given to the role of precursor-film microstructure in regulating organic ammonium salt transport and conversion completeness. The photovoltaic performance of regular and inverted W-PSCs is subsequently compared, and the possible origins of their performance differences are discussed from the perspectives of precursor-film formation, perovskite conversion, film morphology, and interfacial properties. Finally, future opportunities in substrate-interface regulation, scalable aqueous processing, precursor and additive design, and life-cycle assessment are outlined. This review provides a reaction-diffusion-based perspective for understanding and improving water-based perovskite photovoltaics. Full article

Gold-sputtered tapered optical fiber (Au-TOF) sensors were developed for high-sensitivity refractive-index (RI) detection using aqueous glucose standards spanning 1.33–1.41 RIU (0–50% w/v). The sensors were fabricated using a reproducible workflow combining flame-brushing tapering, plasma surface preparation, and rotational magnetron sputtering, enabling azimuthally uniform gold coatings without the use of thiol or sulfur linker chemistries. Two sputtering durations (24 s and 30 s) were investigated to examine thickness-dependent plasmonic coupling and sensing performance. Optical measurements were conducted using a broadband supercontinuum source and compact spectrometer within a 20 µL microfluidic sensing chamber. Increasing glucose concentration produced a monotonic decrease in transmission intensity and a systematic red shift of the resonance minimum, consistent with enhanced evanescent-field interaction at the gold–dielectric interface. Across four independent trials, the 24 s Au-TOF sensor exhibited sensitivities up to 985 nm/RIU, while the 30 s device achieved sensitivities up to 1590 nm/RIU with strong linearity (R² = 0.99). The enhanced sensitivity observed for the longer sputtering duration is attributed to improved gold film continuity and stronger plasmonic coupling. These results demonstrate a scalable, linker-free fabrication strategy for plasmonically enhanced tapered fiber sensors and establish the Au-TOF platform as a promising approach for label-free optical biosensing in compact microfluidic environments. Full article

Micron-sized spherical gold powders possessing high dispersibility and favorable sintering performance are critical for high-performance thick-film gold conductor pastes. Herein, monodisperse micron-sized spherical gold powders were fabricated through an environmentally benign chemical reduction route, where L-ascorbic acid served as the reductant and gum arabic acted as the dispersant. The influences of solution pH, reaction temperature, stirring speed and reaction time on particle morphology and size distribution were systematically explored. With the mass ratio of gold precursor to reductant maintained at 1:1, the optimal synthetic conditions were determined as pH 3, 20 °C, 550 rpm and 20 min. Under such optimized conditions, spherical gold particles with an average diameter of 0.88 μm were harvested, featuring narrow particle-size distribution, high sphericity, good dispersibility and low organic residue of 0.70 wt%. The as-prepared powder delivered high crystallinity and appropriate sintering activity. Quantitative porosity characterization demonstrated that the thick film derived from this micron-scale gold powder achieved the minimum residual porosity in comparison with the other two counterparts, verifying its outstanding densification behavior. Benefiting from the well-developed dense conductive network, the resultant thick film achieved a low sheet resistance of 1.73 mΩ/sq, a superior adhesion strength of 3.65 N/mm², as well as reliable multi-firing stability. This work offers a feasible approach for large-scale manufacturing of high-quality gold powders toward thick-film electronic devices. Full article

Traditional microwave-absorbing metasurfaces struggle to integrate optical transparency with ultra-wideband and high-efficiency microwave absorption, severely limiting their deployment in optoelectronics-compatible electromagnetic protection. To address this constraint, we propose a transparent ultra-wideband microwave-absorbing metasurface based on multilayered indium tin oxide (ITO) films. The unit cell is constructed using a multilayered PMMA dielectric configuration, where ITO conductive layers are patterned as a top square patch, middle square rings, and a continuous bottom film. Full-wave parametric optimization, combined with multilayer resonant coupling, effectively extends the absorption bandwidth. We elucidate the underlying broadband absorption mechanism by analyzing electromagnetic field and surface current distributions at typical resonant frequencies. Furthermore, we systematically investigate the impacts of ITO sheet resistance, incident angle, and polarization state on absorption performance. A 6 × 6 array prototype is fabricated and experimentally characterized in a microwave anechoic chamber. The measured results demonstrate that the proposed metasurface achieves an absorptance exceeding 90% across 9.2–40.2 GHz, delivering a fractional bandwidth of 125.5%. The experimental responses are in good agreement with numerical simulations, and the fabricated prototype retains good optical transparency. Benefiting from the synergistic integration of ultra-wideband microwave absorption and superior optical transmissivity, this multilayer stacked metasurface offers a promising strategy for advanced optoelectronics-compatible stealth and transparent electromagnetic shielding applications. Full article

Tungsten trioxide (WO₃) and molybdenum trioxide (MoO₃) are redox-active Group VI transition-metal oxides widely used in functional thin-film technologies. Many studies have examined single-phase WO₃ and MoO₃ films. However, WO₃/MoO₃ nanocomposite thin films and heterostructures have not yet been comprehensively reviewed as interface-engineered platforms for smart and sustainable technologies. This review addresses this gap by analyzing WO₃/MoO₃ thin-film nanocomposites through the concept of interfacial synergy. Particular attention is paid to the structural complementarity of WO₃ and α-MoO₃, oxygen nonstoichiometry, mixed W⁶⁺/W⁵⁺/W⁴⁺ and Mo⁶⁺/Mo⁵⁺/Mo⁴⁺ valence states, crystallographic-shear suboxides, W–O–Mo interfaces, and fabrication routes for mixed, graded, and multilayer films. The functional advantages of these systems do not arise from simply combining the two oxides. Instead, they result from charge and oxygen-vacancy redistribution, shortened ion–electron transport pathways, phase stabilization, and the formation of new active sites at interface boundaries. The review also emphasizes the need to distinguish genuine interfacial synergy from apparent improvements caused by surface area, film thickness, porosity, hydration, or measurement conditions. Finally, the review links structural features, defect chemistry, and interface-controlled properties to device-level functionality. This framework highlights promising directions for WO₃/MoO₃ nanocomposite films in a wide range of smart and sustainable technologies. Full article

The extensive use of petroleum-based packaging materials has generated significant environmental concerns because of their poor biodegradability and their contribution to plastic pollution. Growing attention has therefore been directed toward sustainable packaging systems derived from renewable resources. Among these alternatives, proteins recovered from pea-processing by-products have emerged as promising film-forming materials because of their biodegradability, renewability, and compatibility with circular-bioeconomy principles. This review critically synthesises, rather than merely catalogues, the development of pea protein-based films produced with different biopolymer matrices, with emphasis on fabrication methods, film-formation mechanisms, physicochemical and mechanical properties, barrier performance, and antimicrobial/antioxidant functionality. Where the literature reports conflicting or concentration-dependent results—for example, the divergent effect of essential oil type on tensile strength, or the existence of optimal polyphenol-loading thresholds beyond which mechanical and barrier performance deteriorate—mechanistic explanations grounded in protein additive interactions, cross-link density, and matrix polarity are proposed and discussed. Quantitative barrier and mechanical data extracted from the reviewed studies are compiled and compared on a normalised basis, and the regulatory, safety, and scale-up barriers relevant to active pea protein-based packaging (EU food-contact-material compliance, migration testing, allergenicity, and life-cycle assessment) are discussed explicitly given the review’s focus on active food packaging. Overall, pea protein-based biodegradable films represent a promising and scientifically active alternative to petroleum-derived packaging materials, but their translation to commercial active-packaging products will depend on resolving moisture sensitivity, establishing standardised testing protocols, and generating the regulatory and techno-economic evidence base that is currently lacking. Full article

Temperature-dependent characterization of nanomaterials is commonly performed through electrical measurements, and many temperature-sensing applications similarly rely on electrical readout signals. Although these approaches are simple and widely used, they require direct sample contact and may lose sensitivity when the electrical response is weak, saturated, or only weakly dependent on temperature. In this study, a photoacoustic (PA) measurement system was used to evaluate the temperature-dependent response of AgNW networks. PA measurement system detects ultrasonic waves generated through transient thermoelastic expansion after optical absorption, which enables sensitive probing of temperature-dependent optothermal responses beyond conventional electrical measurements. Silver nanowire (AgNW) films with different surface coverage were fabricated through one to four repeated spin-coating cycles using a 1% AgNW ethanol dispersion containing nanowires with diameters of 20–40 nm and lengths of 10–20 µm. The photoacoustic (PA) signals of the fabricated films were measured at various temperatures using a customized PA measurement system and were compared with sheet resistance values obtained using a four-point probe. Both sheet resistance and PA signals increased with increasing temperature, regardless of AgNW surface coverage. Notably, AgNW films with higher surface coverages showed only weak temperature dependence in sheet resistance but pronounced temperature-dependent PA response. These results indicate that PA analysis is particularly useful for characterizing AgNW networks with higher surface coverage, including those used in stretchable electrodes. All samples showed linear relationships for both sheet resistance and PA signals, with coefficients of determination (R²) exceeding 0.9. Overall, these findings suggest that PA measurement may provide complementary information on temperature-dependent behavior that is not fully reflected in sheet-resistance measurements. Full article

Three kinds of surface treatments, including permanganate, molybdate, and phytic acid conversion films, were fabricated on La-Ce mischmetal containing AM60B magnesium alloy. Their effects on the corrosion and tribological behaviors of the alloy in 3.5 wt% NaCl solution were systematically investigated via Mott–Schottky analysis, electrochemical measurements, and friction–wear tests. The results show three surface treatments shift the flat band potential in the negative direction, reduce the corrosion current density, enlarge the electrochemical impedance arc radius, and decrease the friction coefficient, conferring remarkably enhanced corrosion and wear resistance to the alloy substrate. The performance enhancement is ascribed to the formation of uniform, dense conversion films that act as effective physical barriers, which impede the penetration of corrosive species, isolate the substrate from the aggressive aqueous environment, and improve the chemical and electrochemical stability of the alloy–solution interface. The comprehensive performance ranking of the three surface treatments in terms of corrosion and wear resistance is as follows: permanganate conversion film > molybdate conversion film > phytic acid conversion film. Full article

Transparent glazing systems are increasingly required to provide simultaneous control over light transmission, solar heat gain, thermal losses, surface contamination, and environmental durability, creating new challenges for the development of multifunctional coating technologies. This review critically examines advanced optical and self-cleaning coatings developed for transparent glass and polymeric substrates, with particular emphasis on the relationships between materials chemistry, surface/interface chemistry, microstructure, and functional performance. Dielectric multilayers, metal oxides, ceramic coatings, sol-gel-derived hybrid systems, and emerging chromogenic materials are discussed in terms of their chemical compositions, structural characteristics, and mechanisms governing optical, thermal, and surface properties. Particular attention is given to structure–property relationships associated with photosynthetically active radiation (PAR) transmission, near-infrared (NIR) management, thermal emissivity, solar modulation, wettability, and self-cleaning behavior, together with their implications for energy-efficient transparent glazing and greenhouse environments. The influence of coating architecture, porosity, surface roughness, interfacial interactions, and deposition conditions on functional performance and long-term stability is critically evaluated. The advantages and limitations of representative deposition strategies are further compared, considering scalability, process compatibility, substrate sensitivity, and application to heat-sensitive polymeric films. Environmental degradation mechanisms induced by ultraviolet irradiation, moisture, thermal cycling, and mechanical stresses are analyzed to identify the key factors governing coating durability and sustainability. Finally, current knowledge gaps and emerging research directions are identified, highlighting the need for rational materials design, multifunctional integration, scalable fabrication, and improved structure-property-durability correlations for next-generation transparent glazing and greenhouse applications. Full article

In this work, a Fe-based amorphous coating (Fe₄₄Cr₁₈Mo₇Ni₄Cu₂B₂₀Si₃C₂) was fabricated via high-velocity oxygen fuel (HVOF) spraying, and the effect of annealing temperature on its microstructure, phase composition, and corrosion resistance in 3.5 wt.% NaCl solution was investigated. The as-sprayed (AS) coating exhibits an amorphous content of 85.71% and a porosity of 1.37%. Annealing at 540 °C (H540) reduces porosity to 0.98% without significant crystallization, whereas annealing at 640 °C (H640) and 740 °C (H740) triggers extensive crystallization (amorphous content drops to 24.18% and 19.20%), and porosity increases to 1.82% and 2.17%. Electrochemical tests show that corrosion resistance deteriorates progressively with increasing temperature. i_corr increases from 3.56 μA/cm² (AS) to 50.0 μA/cm² (H740), while R_p decreases from 8472 to 669 Ω·cm². EIS reveals that the AS coating is dominated by the inner barrier layer (R_b >> R_t), whereas annealing causes a drastic collapse of R_b (from 8.374 × 10⁴ to 5.011 Ω·cm²). This degradation is attributed to crystallization-induced grain boundaries and reduced effective Cr content, which impair passive film integrity and accelerate corrosion. Full article

Surface wettability is a critical factor influencing the biological performance of orthopedic Ti implants. The native TiO₂ film on Ti undergoes changes in wettability under ultraviolet (UV) irradiation. However, the limited tissue penetration of UV light compared with near-infrared (NIR) light restricts its potential clinical application. In this study, a black TiO₂ (b-TiO₂) coating with NIR-responsive wettability was fabricated directly on a Ti substrate using a one-step atmospheric plasma spraying process. Under 808 nm NIR irradiation, the water contact angle of the b-TiO₂ coating increased from 0° to 154.4 ± 4.0°, indicating a transition from a superhydrophilic to a stable superhydrophobic state. FTIR and XPS analyses showed that NIR-induced photothermal heating promoted the removal of surface hydroxyl groups and the passivation of oxygen-deficient sites, thereby driving the wettability transition. Among TiO₂ coatings with hydrophilic, intermediate-wettability, and hydrophobic surfaces, the hydrophobic coating effectively directed macrophage polarization toward the anti-inflammatory M2 phenotype and delivered slightly superior osteoblast activity. It also markedly inhibited Staphylococcus aureus adhesion, achieving an anti-adhesion efficiency of 98.61%. These findings demonstrate that NIR irradiation can regulate the wettability of plasma-sprayed b-TiO₂ coatings and provide concurrent immunomodulatory and antibacterial effects. This approach may support the development of light-responsive surfaces for orthopedic implants. Full article

A^IVB^VI semiconductors, particularly lead chalcogenides, remain key materials for mid-wave infrared (MWIR) photodetection due to their narrow bandgap and exceptional carrier transport properties. However, the realization of high-quality p-type PbTe thin films, suitable for p–n junction devices, remains a technological challenge. In this work, we report the fabrication of high-mobility p-type PbTe thin films grown on muscovite mica by electron beam-assisted physical vapor deposition. The films were derived from a Te-rich Pb_0.999Te_1.001 ingot, enabling controlled acceptor formation via excess tellurium. Structural characterization reveals growth with strong (111) texture, large grain size, and low surface roughness. Comprehensive electrical measurements in the range of 80–300 K show a record room-temperature hole mobility of 876 cm²/V·s, achieved under optimized fabrication conditions. This figure approaches values typical for epitaxial n-type PbTe, indicating low scattering and high crystallinity. These results establish an effective route for producing strongly (111)-textured p-type PbTe films with high room-temperature hole mobility through optimized deposition and post-deposition annealing. Full article