Search Results (4,179)

An experimental investigation was conducted to evaluate the thermal conductivity (TC) and local heat-transfer coefficients (LHTCs) of nanofluids containing alumina (Al₂O₃), hematite (Fe₂O₃), and copper oxide (CuO) nanoparticles dispersed in deionized water. A newly developed non-invasive LHTC probe was integrated into the inner wall of the test section to enable direct quantification of interfacial heat-transfer performance. The measurements were conducted under laminar and turbulent flow conditons across Reynolds numbers ranging from 1000 to 10,000. The selected nanoparticles were chosen based on their high intrinsic thermal conductivity, cost effectiveness, and, in the case of Fe₂O₃, magnetic recoverability. The nanoparticles enhanced both TC and LHTCs through improved thermophysical propoerties and possible interfacial effects. Maximum TC enhancements of 19%, 21%, and 25% were achieved for Al₂O₃/distilled water (DW), Fe₂O₃/DW, and CuO/DW nanofluids, respectively, at 0.05 vol% and 55 °C, while the corresponding LHTC enhancements reached 44%, 50%, and 53%. Under turbulent flow, CuO/DW exhibited the highest heat-transfer performance, attributed to a 25% increase in TC and corresponding improvement in connective heat transfer. Since the boundary-layer thickness exceeded the nanoparticle diameter (30 nm), nanoparticles penetrated the interfacial film, inducing localized micro-convection and catalytic micro-mixing, which intensified interfacial heat transport. The experimentally determined Nusselt numbers showed strong agreement with the Xuan–Qiang correlation at 55 °C, suggesting that the nanoparticle volume fraction governs the catalytic interfacial heat-transfer mechanism. Full article

Biodegradable active packaging that incorporates food-grade additives offers a promising solution for extending shelf life and minimizing food waste. This study investigates the development of functional packaging films for cheese applications by blending thermoplastic starch (TPS) and poly (butylene adipate-co-terephthalate) (PBAT) in a 60/40 (w/w) ratio with various concentrations of sodium lactate (SL; 1–7% w/w) using blown-film extrusion. Spectroscopic analyses, including ¹H NMR and FTIR, confirmed the presence of hydrogen-bonding and ionic interactions between the hydroxyl (–OH) groups of thermoplastic starch (TPS) and the carboxylate (–COO⁻) groups of sodium lactate, which enhanced interfacial compatibility and produced smoother, more compact film morphologies. SL acted as a multifunctional plasticizer and compatibilizer, improving film flexibility while slightly reducing tensile strength. Notably, SL incorporation increased water vapor permeability and surface wettability but significantly decreased oxygen permeability to below 1 cc·mm/m²·day·atm. At moderate concentrations (≥ 3% w/w), SL also exhibited antimicrobial activity against Staphylococcus aureus. When applied to cheese packaging, SL-modified films effectively maintained color stability for up to 9 days under refrigerated storage. Notably, cheeses packaged with films containing 3–7% (w/w) SL exhibited significantly lower hardness values than the control on day 3, indicating improved moisture retention and texture preservation, although these differences were no longer significant by day 9. These findings demonstrate that sodium lactate can simultaneously enhance interfacial miscibility, oxygen barrier performance, and antimicrobial functionality in sustainable, biodegradable active packaging systems. Full article

Seawater flotation is increasingly adopted to reduce freshwater demand; however, its complex ionic environment often deteriorates sulfide mineral floatability and necessitates effective regulation strategies. In this work, seawater magnetization and collector magnetization were evaluated as two independent treatment routes affecting chalcopyrite flotation, and their impacts on flotation performance and interfacial properties were quantified. Pure-mineral flotation tests were conducted at pH 8 using butyl xanthate as the collector and pine oil as the frother, with magnetic field strength and magnetization duration varied in a controlled manner. Both flotation recovery and interfacial responses exhibited a distinct parameter-window behavior, rather than a monotonic enhancement. Under magnetized seawater conditions, chalcopyrite recovery increased from 80.45% to 92.7% at 200 mT and 8 min, while magnetized collector treatment under identical conditions produced a stronger enhancement, yielding a maximum recovery of 96.5%. Contact-angle measurements demonstrated an increase in chalcopyrite surface hydrophobicity within the effective magnetization range, whereas zeta-potential measurements revealed a positive shift toward less negative values, indicating weakened electrostatic repulsion in the seawater system. The consistent trends among flotation recovery, surface wettability, and surface electrical properties suggest that magnetization influences chalcopyrite floatability by modifying the balance between hydrophobic surface stabilization and electrostatic interactions, thereby highlighting an effective operating window for seawater flotation systems. Full article

Microplastics (MPs) are an increasingly pervasive pollutant, prompting interest in using them as a waste valorization feedstock in cementitious composites—most commonly as partial replacements for mineral aggregates. This review critically assesses the technical feasibility and implications of this approach based on current experimental and analytical evidence. Across the literature, MPs differ fundamentally from natural aggregates in stiffness, density, and surface chemistry, which weakens particle packing and interfacial bonding. Consequently, MP–aggregate substitution typically reduces workability and compressive strength and degrades durability-related performance, including resistance to chloride ingress, carbonation, and freeze–thaw action, with adverse effects generally increasing at higher replacement levels. While isolated benefits such as reduced unit weight and occasional post-cracking responses have been reported under specific mix designs, untreated MPs usually behave as mechanically inactive inclusions and stress concentrators rather than effective reinforcement. Major uncertainties remain regarding long-term durability and the risk of secondary MP release. Overall, MP-based aggregate replacement should be considered a conditional, application-specific strategy, currently most defensible for non-structural or function-driven applications under carefully defined performance and environmental criteria. Full article

Civil engineering infrastructure suffers material degradation, shortened service life and high maintenance costs under harsh environments and natural aging, threatening public safety. Nanopolymer composites, featuring designable microstructures and excellent macroscopic properties, provide a revolutionary solution to improve the weather resistance and toughness of civil engineering materials. This paper systematically clarifies the modification mechanisms of nanocomposites, focusing on nanofiller–polymer matrix interfacial interactions (physical adsorption, chemical bonding) and their synergistic effects in enhancing environmental aging resistance (UV, corrosion, freeze–thaw) and mechanical performance (toughening, strengthening, dynamic load resistance). It summarizes the latest applications in nanomodified protective coatings, sealing/bonding materials and composite structural components, revealing the inherent “structure-property-application” relationships. Furthermore, this paper addresses core large-scale application challenges, including technical bottlenecks, performance evaluation limitations and economic/environmental barriers. Finally, future research directions are proposed, covering multifunctional intelligent materials, green development, interdisciplinary computational methods and standardized systems. This review offers an integrated perspective, providing theoretical guidance and practical references for advancing durable, resilient and sustainable civil engineering. Full article

In this work, a rational catalyst design based on interfacial architecture engineering is proposed for low-temperature dry methane reforming (DMR) at 550 °C. Ni-based catalysts containing 10 wt% Ni were developed on a γ-Al₂O₃ support modified with 9 wt% MgO–1 wt% ZrO₂. Zirconia promoters were introduced either by dry impregnation or via an ammonia vapor-assisted route to construct a Ni–NiO–ZrO₂ interfacial network. The effects of ZrO₂ content (0, 1, and 3 wt%) and synthesis route on metal–support interactions, oxygen mobility, and coke resistance were systematically investigated. ZrO₂ promotion increased the fraction of reducible Ni species and preferentially enhanced CO₂ activation, thereby promoting the reverse water–gas shift (RWGS) reaction and lowering the H₂/CO ratio. In contrast, ammonia vapor-assisted preparation induced the formation of an LDH-derived Ni–NiO–ZrO₂ surface network, which increased the concentration of surface-accessible Ni species, suppressed excessive zirconia coverage, and significantly improved apparent oxygen mobility. These synergistic structural features are consistent with enhanced oxygen-assisted carbon removal and improved coke management through regulation of the nature of carbon species, leading to more balanced activation of CH₄ and CO₂. Overall, this study provides insights into interfacial structure–performance relationships for designing efficient Ni-based catalysts for CO₂ utilization. Full article

Staphylococcus aureus, particularly its multidrug-resistant strains, poses a critical biological hazard throughout the global food supply chain, underscoring the need to transition from inert petroleum-based packaging to active, biodegradable alternatives. This review presents a comprehensive analysis of the structure function relationships and interfacial interaction mechanisms that govern polysaccharide-, protein-, and lipid-based films designed for the targeted inhibition of S. aureus. We critically evaluate the extent to which the intrinsic molecular features—such as the polycationic charge density of chitosan and the amphiphilic self-assembly of fatty acids—determine baseline antibacterial activity. A key contribution of this work is the elucidation of three synergistic pathways: physical barrier effects, chemical interference, and biological regulation. Furthermore, we discuss how composite systems, such as polysaccharide lipid hybrids and protein nanomaterial scaffolds, exploit charge complementarity and controlled-release kinetics to surpass the performance limitations of single-component materials. Finally, we address the critical trade-offs between mechanical integrity and antimicrobial efficacy, proposing a roadmap for intelligent, stimuli-responsive packaging that is capable of responding to microbial metabolic cues. Overall, this review provides a theoretical foundation for the rational design of high-performance biodegradable films to safeguard global food safety. Full article

The construction of Z-scheme heterojunctions is regarded as one of the most effective modification strategies for photocatalysts. However, how to improve the interfacial charge transfer efficiency to further enhance the photocatalytic activity remains an urgent issue to be addressed. In this study, sulfur vacancy-enriched ZnIn₂S₄/MoS₂ Z-scheme heterojunctions (V-ZIS/MS) containing interfacial Mo-S bonds was successfully synthesized using a hydrothermal method. The V-ZIS/2%MS showed the highest hydrogen evolution rate, achieving 19.21 ± 0.78 mmol·g⁻¹·h⁻¹ under visible light and 112.89 ± 10.98 mmol·g⁻¹·h⁻¹ under full-spectrum illumination, which are 5.07 and 4.41 times higher than ZIS (3.79 ± 0.79 mmol·g⁻¹·h⁻¹) and V-ZIS (4.36 ± 0.98 mmol·g⁻¹·h⁻¹) under visible light, respectively, outperforming most reported ZIS-based photocatalysts. This is because the composite of V-ZIS and MS enhanced its light absorption performance. More importantly, the formation of Mo-S bonds at the V-ZIS/MoS₂ interface facilitated efficient charge transfer and reduced interfacial resistance, leading to significantly improved photocatalytic activity. Cycling experiments further demonstrate that V-ZIS/2%MS exhibits considerable photocatalytic stability. X-ray diffraction analysis before and after the reaction further confirmed the structural stability of the catalyst. This work provides a certain reference for the preparation of high-performance ZIS-based photocatalysts. Full article

The utilization of waste and renewable oils as asphalt modifiers is a crucial strategy for achieving sustainable development in pavement engineering. However, the different physicochemical effects exerted by oil sources (bio-based versus petroleum-based) on the asphalt–aggregate interface remain insufficiently understood. This study aims to elucidate the influence mechanism of two bio-based oils and two petroleum-based oils on asphalt adhesion and the pavement performance of mixtures. A quantitative evaluation method combining the boiling test with digital image processing (DIP) technology was developed to assess the anti-stripping performance of modified asphalt on different lithological aggregates (acidic granite and alkaline limestone). Additionally, Fourier transform infrared spectroscopy (FTIR) was employed to reveal the chemical evolution of the modified asphalt. The results indicated that, although all oil-based modifiers demonstrated excellent compatibility and storage stability with the base asphalt (segregation ratio < 5%), their adhesion properties were significantly influenced by aggregate lithology. The key finding was that, compared to petroleum-based oils, bio-based oils exhibited superior adhesion performance on acidic granite surfaces, markedly mitigating moisture-induced stripping. FTIR analysis confirmed that this enhancement was attributable to the aromatic and carbonyl functional groups introduced by bio-based oils, which effectively promoted the interfacial bonding. Furthermore, bio-oil-modified mixtures exhibited optimal low-temperature cracking resistance without compromising high-temperature stability. These findings elucidate the mechanism by which bio-oil enhances the water-damage resistance of acidic aggregate systems, providing a theoretical basis for the optimized selection of sustainable asphalt modifiers. Full article

In this work, the deposition of graphene coatings on substrates of an ELI grade Ti-6Al-4V alloy was carried out using the Plasma Enhanced Chemical Vapor Deposition (PECVD) technique. The purpose of this study was to improve the surface properties of the material. The characterization of the material was carried out by non-destructive techniques, such as Raman Spectroscopy and Thermoelectric Potential. A preliminary characterization of Ti substrates was carried out by Raman spectroscopy. Conversely, thermoelectric potential tests were conducted using three distinct tip systems and four different temperature gradients. Lastly, some surface roughness measurements were conducted on all samples, both coated and uncoated. Graphene micro-structured coatings were obtained using a plasma-activated mixture of hydrogen and methane gases with an equimolar feed ratio (1:1 H₂:CH₄) at a temperature of 850 °C and a plasma exposure of 150 Watts and duration of 15 min. Raman spectra verified the presence of uniform micrometric graphene on the surface of Ti substrates. Graphene-coated Ti-6Al-4V ELI substrates exhibited Seebeck coefficient values indicating metallic-like behavior and suitability for thermoelectric sensing. In the eddy current analyses, it was found that low frequencies provided the highest sensitivity for differentiating between samples. An inverse relationship was identified between substrate thickness and phase angle, and a direct relationship with calculated electrical conductivity was also identified. This direct relation is attributed to penetration depth and interactions due to the chemical nature of the substrate and coating. Despite a slight increase in surface roughness after graphene deposition, values remained comparable to the base alloy, preserving compatibility for biomedical integration. Thermoelectric potential measurements revealed enhanced sensitivity to surface morphology and interfacial effects when high-sensitivity probe configurations were employed. These results support potential applications in implantable or wearable temperature sensors, energy harvesting devices, and smart biomedical interfaces. The thickness of the graphene coating was also characterized by SEM, which showed that the films deposited by PECVD are about 1 micron thick. Full article

Microencapsulated phase change materials (MPCMs) offer a promising way to enhance the thermal performance of cement-based materials; however, their incorporation often compromises mechanical properties and durability, limiting practical application. A mechanistic understanding of how MPCM particle size governs the coupled thermal, mechanical, and transport behavior of cementitious systems remains incomplete. In this paper, two organic MPCMs with identical core–shell chemistry but distinct particle sizes (mean diameters of 10.78 μm and 34.21 μm) were incorporated into mortar at dosages of 10 wt.% and 20 wt.% under w/b ratios of 0.35 and 0.45. The effects of MPCM particle size and content on hydration kinetics, rheology, strength development, pore transport behavior, and thermal conductivity were systematically investigated using isothermal calorimetry, flow spread testing, compressive strength measurements, capillary water absorption, thermal conductivity analysis, X-ray diffraction, and SEM–EDS characterization. Results show that MPCM incorporation delays early-age hydration and reduces peak hydration rates, with finer particles exerting a stronger inhibitory effect due to increased specific surface area and water adsorption. While all MPCM-modified mortars exhibit reduced compressive strength and increased capillary absorption, larger MPCM particles mitigate strength loss by limiting the total interfacial transition zone (ITZ) area and reducing ITZ connectivity. In contrast, smaller MPCM particles more effectively decrease thermal conductivity, achieving up to a 33% reduction, owing to enhanced interfacial thermal resistance. Microstructural observations confirm that MPCMs do not alter cement hydration products but influence performance through interfacial defects, porosity evolution, and particle-scale interactions. These findings demonstrate that MPCM particle size critically controls the trade-off between thermal regulation and structural integrity, providing quantitative guidance for designing PCM-modified concrete through optimizing particle-size. Full article

Droplet impact dynamics is a critical subject in interfacial fluid mechanics, with applications in aerospace, energy transport, microfluidics, and chemical engineering. This study investigates the impact behavior of double droplets on cylindrical surfaces, focusing on the interaction dynamics and the effects of parameters such as Weber number, droplet spacing, and surface curvature. Using numerical simulations, the study identifies three distinct rebound modes—twin-wing rebound, vertical rebound, and arc-shaped rebound—regulated by the Weber number and droplet spacing. Results show that increasing the Weber number enhances spreading and reduces contact time, with the arc-shaped rebound mode resulting in the shortest contact times. Droplet spacing further influences the dynamics, with wider spacing increasing contact time due to additional retraction phases. The findings provide valuable insights into the complex multi-field interactions governing droplet behavior on curved surfaces, offering new perspectives for the design of anti-icing coatings and curved microfluidic devices. Full article

Hydrogen is a key energy carrier for fuel cell vehicles and hydrogen energy systems. However, its colorless and odorless nature, combined with a wide flammability range, poses significant safety risks in the event of leakage. Accordingly, compact and reliable hydrogen sensors capable of low-ppm detection at moderate operating temperatures are essential for early-stage safety monitoring. In this study, a bias-optimized hydrogen gas sensor based on a Pd-functionalized SnO₂ thin film with Mo electrodes and an integrated microheater is designed, fabricated, and systematically characterized. The sensor employs a Mo-based vertical microheater and a multilayer thermal insulation stack, enabling thermally efficient and stable operation at 250–280 °C with low power consumption. The electrical and sensing properties of the SnO₂ layer are optimized by controlling the oxygen partial pressure during reactive sputtering and post-deposition annealing. The Pd catalytic layer promotes hydrogen dissociation and spillover, resulting in pronounced resistance modulation through surface redox reactions and interfacial charge transport effects. By systematically optimizing the sensing bias voltage, a clear trade-off between sensitivity enhancement and electrical noise is identified, which allows stable and repeatable operation in the low-ppm regime. The sensor response follows a power-law dependence on hydrogen concentration, and an automated measurement platform is employed to evaluate repeatability and statistical performance. Based on baseline noise analysis and concentration-dependent resistance variation, a limit of detection of approximately 6.4 ppm is achieved. Furthermore, a concentration-normalized figure of merit that combines response magnitude and concentration dependence is introduced to quantitatively assess low-concentration hydrogen sensing performance. These results demonstrate that the proposed Mo-electrode Pd/SnO₂ thin-film sensor, enabled by bias-optimized operation and integrated thermal control, provides a robust and scalable platform for safety-critical hydrogen leak detection. Full article

Low-frequency oscillatory flow is a long-standing instability in cryogenic jet condensation systems and is closely associated with abnormal pressure fluctuations in propulsion pipelines. While previous studies mainly focused on operating conditions, the role of injector orifice layout in triggering low-frequency oscillations remains unclear. In this work, a three-dimensional numerical investigation was conducted to examine the effect of orifice layout on condensation-induced oscillatory flow in an oxygen jet condensation system. A curvature-coupled mass transfer model is employed, in which the interfacial mass transfer rate is dynamically linked to local vapor–liquid interfacial curvature, enabling accurate representation of interfacial evolution. A series of numerical cases are designed by varying the number, arrangement, and diameter of orifices under different combinations of mass rate, mass flux, and total injection area. Two distinct condensation patterns are identified: suck-back chugging and weak pulsation. Pronounced low-frequency oscillations are observed only for specific orifice layouts. When the total injection area and gaseous oxygen mass rate are maintained, chugging persists under different layouts, producing dominant frequencies of approximately 10~11 Hz and pressure amplitudes of about 80~120 kPa. Once either the total area or mass rate is altered, the system transitions to weak pulsation with pressure fluctuations below 3 kPa. These results demonstrate that low-frequency oscillatory flow is a layout-enabled instability rather than a mass-flux-controlled phenomenon, highlighting the importance of injector geometric design in regulating condensation-induced oscillations. Full article

We report a comprehensive spectroscopic, microscopic, and device-level investigation of the ambient-driven degradation of PTQ10:IDIC bulk-heterojunction organic solar cells (BHJ-OSCs), up to 500 h. The power conversion efficiency dropped from 9.51% to 7.69% (≈19% relative loss), primarily due to a decrease in short-circuit current density (J_SC 15.93 to 13.82 mA cm⁻²), while the open-circuit voltage remained largely stable (0.92 to 0.90 V). Atomic force microscopy reveals surface smoothing upon ageing, with the root-mean-square roughness decreasing from 4.29 to 3.45 nm, and the UV–vis absorption spectra show negligible changes, indicating preserved bulk light-harvesting capability. In contrast, X-ray photoelectron spectroscopy indicates pronounced surface compositional evolution, with a decrease in oxygen (5.18 to 3.18%) and a substantial increase in fluorine content (3.23 to 7.23%), consistent with fluorine-rich surface segregation or reorientation. Ultraviolet photoelectron spectroscopy further reveals a 0.48 eV reduction in surface work function, indicative of surface dipole modification and near-surface electronic reorganization. Collectively, these results demonstrate that ambient ageing primarily impacts interfacial chemistry and morphology rather than bulk optoelectronic properties, highlighting interfacial engineering and encapsulation as effective strategies for improving long-term device stability. Full article