Search Results (1,015)

Nanofluids have long been explored for enhancing heat transfer, with early studies focusing primarily on improved thermal conductivity. However, in spray and droplet cooling applications, recent research indicates that conductivity alone cannot fully account for the observed performance gains. Additional mechanisms, such as Brownian-motion-induced convection, dynamic wetting, and nanoparticle-driven surface modification, significantly affect droplet impact dynamics, spreading behavior, boiling transitions, and transient heat transfer during impact and evaporation. This review critically synthesizes these effects, emphasizing how nanofluids interact with complex flow fields, steep thermal gradients, and heated substrates. It also examines emerging strategies for optimizing nanofluid design, including hybrid suspensions and phase-change-enhanced formulations. These developments open new avenues for high-efficiency cooling in electronics, renewable energy systems, and industrial spray processes. By moving beyond thermal conductivity as the sole performance metric, this review promotes a multi-scale, interdisciplinary framework for advancing nanofluid-based thermal technologies that align with sustainability, energy efficiency, and cost effectiveness. Full article

In this study, a scalable surface modification strategy for M2 high-speed steel was applied using multiple-pass friction stir processing (FSP) with overlapping ratios of 25%, 50%, and 75%. A comprehensive investigation of the microstructure, surface hardness, wear, and corrosion resistance was conducted to elucidate the properties of FSPed M2 as a function of the overlapping ratio. In the single-pass FSPed M2, the major phase was martensite and the minor phases included retained austenite where refined carbides (M₆C, M₂₃C₆, and MC) were detected. However, back-tempering occurred near the overlapped zone (OZ) between consecutive tracks for the multiple-pass FSPed M2. The martensite formed in the first pass was turned into tempered martensite by the thermal cycle from the subsequent pass. This back-tempering resulted in a localized decline in hardness from 900 to 650 HV_0.2. Further wear tests revealed that the wear rates of the tempered zone (TZ) of the multiple-pass FSPed M2 (FSP25%: 1.40 × 10⁻⁵ mm³/N·m, FSP50%: 1.20 × 10⁻⁵ mm³/N·m and FSP75%: 1.00 × 10⁻⁵ mm³/N·m) are all higher than that of SZ of the single-pass FSPed M2 (0.75 × 10⁻⁵ mm³/N·m), indicating lower wear resistance of the TZ. Moreover, increased carbide content in the TZ led to the depletion of passivating elements near proximity of the tempered martensite, acting as the active sites for selective corrosion attack. The corrosion potential (E_corr) and corrosion current density (I_corr) increased significantly, with values of −397.6 ± 5.6 mV and 9.5 ± 0.8 μA·cm⁻² for FSP25%, −424.4 ± 6.0 mV and 14.7 ± 1.7 μA·cm⁻² for FSP50%, and −440.9 ± 2.8 mV and 17.1 ± 1.9 μA·cm⁻² for FSP75%. Full article

As an emerging thermal insulation material, silica aerogel holds broad application prospects in building energy conservation. Silica aerogel based waterborne coatings are low thermal conductivity, readily applicable and environmentally friendly, offering significant advantages for improving building energy efficiency. However, the inadequate dispersibility and agglomeration tendency of silica aerogel in aqueous polymer systems adversely affect coating properties. To address this challenge, a waterborne polyurethane (WPU) coating incorporating 3-aminopropyltriethoxysilane-modified organo-bridged silica aerogel (APTES-OBSA) was developed. Integration of organic segments within organo-bridged silica aerogel (OBSA) framework enhanced compatibility of silica aerogel with organic polyurethane chains, thereby reducing aerogel agglomeration. 3-aminopropyltriethoxysilane (APTES) surface modification of OBSA introduced amino groups that strengthened interfacial interaction between OBSA-WPU, effectively enhancing aerogel dispersion within the aqueous polyurethane matrix. APTES-OBSA loading achieved 20 wt% in WPU composite coatings. Compared to neat WPU coating, the composite coatings achieved 21.6% reduction in thermal conductivity, 10 °C lower temperature under thermal irradiation, and 26.6% higher adhesion. Additionally, the composite coatings demonstrated enhanced thermal stability and good water resistance. The excellent comprehensive performance positions this material as a promising eco-friendly thermal insulation coating for building energy-saving applications. Full article

The construction of buildings using shipping containers (SCs) is a way to extend their useful life. They are constructed by modifying the structure, thermal, and acoustic conditioning by improving the envelope and creating openings for lighting and ventilation purposes. This study explores the architectural adaptation of SCs to sustainable residential housing, focusing on structural, thermal, and acoustic performance. The project centers on a case study in Madrid, Spain, transforming four containers into a semi-detached, multilevel dwelling. The design emphasizes modular coordination, spatial flexibility, and structural reinforcement. The retrofit process includes the integration of thermal insulation systems in the ventilated façades and sandwich roof panels to counteract steel’s high thermal conductivity, enhancing energy efficiency. The acoustic performance of the container-based dwelling was assessed through in situ measurements of façade airborne sound insulation and floor impact noisedemonstrating compliance with building code requirements by means of laminated glazing, sealed joints, and floating floors. This represents a novel contribution, given the scarcity of experimental acoustic data for residential buildings made from shipping containers. Results confirm that despite the structure’s low surface mass, appropriate design strategies can achieve the required sound insulation levels, supporting the viability of this lightweight modular construction system. Structural calculations verify the building’s load-bearing capacity post-modification. Overall, the findings support container architecture as a viable and eco-efficient alternative to conventional construction, while highlighting critical design considerations such as thermal performance, sound attenuation, and load redistribution. The results offer valuable data for designers working with container-based systems and contribute to a strategic methodology for the sustainable refurbishment of modular housing. Full article

Nanoporous gold nanoparticles (np-AuNPs) combine inertness, a nanoscale structure, and a porous framework with high surface area, conductivity, and biocompatibility, making them ideal for biosensing, catalysis, fuel cells, and drug delivery. Their open pore structure and low-coordinated atoms enhance biomolecule capture and mass transfer, while their tunable size, pore volume, and ease of surface modification make them promising biosensor transducers. However, synthesizing colloidal np-AuNPs in a simple way with controllable size and scalability remains challenging. The existing approaches mostly rely on specialized equipment, complex setups, and expert knowledge, while still facing challenges in terms of scalability. In this study, we present a simple, seedless, wet-chemical synthesis of colloidal np-AuNPs via the co-reduction of Au/Ag alloys followed by dealloying. By adjusting the Au:Ag ratio, we produced np-AuNPs sized ~120–530 nm, which were immobilized on electrodes for detecting lipopolysaccharide (LPS), a toxic component of Gram-negative bacterial membranes. The LPS biosensor exhibited excellent sensitivity towards detecting wild-type LPS, with a low limit of detection (LOD) of 0.1244 ng/L. This work demonstrates the effective synthesis and application of np-AuNPs in LPS biosensing. Full article

This study applies the Integrated Modification Methodology (IMM) to assess how morphology-driven, nature-based solutions reduce urban heat island (UHI) effects and flooding in Rio de Janeiro’s Cidade Nova. Multi-scale GIS diagnostics identify green continuity and vertical permeability as critical weaknesses. Simulations (Ladybug/Dragonfly) and hydrological modelling (rational method) quantify the intervention’s impact, including greening, material retrofits, and drainage upgrades. Results show a 38% increase in albedo, a 13% reduction in volumetric heat capacity, and a 30% drop in thermal conductivity. These changes reduce the peak UHI by 0.2 °C hourly, narrowing the urban–rural temperature gap to 3.5 °C (summer) and 4.3 °C (winter). Hydrologically, impervious cover decreases from 22% to 15%, permeable surfaces rise from 9% to 29%, and peak runoff volume drops by 27% (16,062 to 11,753 m³/h), mitigating flood risks. Green space expands from 7.8% to 21%, improving connectivity by 50% and improving park access. These findings demonstrate that IMM-guided interventions effectively enhance thermal and hydrological resilience in dense tropical cities, aligning with climate adaptation and the Sustainable Development Goals. Full article

The paper proposes a manufacturing technology for the non-woven/3D-printed (N3DP) hybrid material (HM) with improved radio-absorbing properties. We have fabricated the needle-punched non-woven felt and impregnated it with the carbon fibers containing UV-curable photopolymer resin. The functional 3D-printed layer was attached to the highly porous, deformable polymer substrate by the fused deposition modeling (FDM) technique. The preliminary bulk modification of the filament was realized with the IR- and UV-pigment microcapsules filling. The combination of additive prototyping and non-woven needle-punched fabrics surface modification (by the electrically conductive elements 2D-periodic system applying) expands the frequency range of the electromagnetic radiation effective absorption. It provides the possibility of a reversible change in the color characteristics of the hybrid material surface under the influence of the UV and IR radiation. Full article

In view of the growing demand for flexible, conductive and functional materials for textile gas sensor applications, the effects of ozonation on the properties of expanded graphite (EG) in textile structures were analyzed. Four types of fabrics (cotton, polyamide, viscose, para-aramid) coated with pastes containing EG, which had previously been subjected to a 15-min and 30-min ozonation process, were examined. The paste was prepared using Ebecryl 2002 and the photoinitiator Esacure DP250 and then applied by screen printing. Surface resistance, scanning microscopy and wetting angle analyses were performed. The results showed that short-term ozonation (15 min) notably improved the electrical conductivity and adhesion of EG to the textile substrate, while longer exposure (30 min) led to deterioration of the conductive properties due to excessive functionalization and fragmentation of the conductive layer. The lowest surface resistance was observed in the sample subjected to 15 min of ozonation. The conclusions indicate that a properly controlled ozonation process can increase the usability of EG in sensor applications, especially in the context of smart clothing; however, the optimization of the modification time is crucial for maintaining the integrity and durability of the conductive layer. Full article

Oil-contaminated wastewater presents a significant environmental challenge, necessitating the development of efficient and adaptable treatment technologies. In this study, a pH-responsive chitosan-coated polyethersulfone (Ch/PES) membrane was developed and systematically evaluated for oil/water separation performance under varying pH conditions. PES was chosen as the base membrane material due to its excellent chemical resistance and mechanical durability, while Ch, a biodegradable and environmentally friendly biopolymer with pH-sensitive properties, was applied as a functional surface coating. The Ch/PES membrane was successfully fabricated and characterized by Fourier-transform infrared spectroscopy and scanning electron microscopy, confirming successful surface modification and structural integrity. Additional analyses—including underwater oil contact angle measurements, porosity assessment, and cross-sectional morphological evaluation—demonstrated the membrane’s dynamic pH-responsive wettability and pore size modulation. Oil emulsion separation experiments, conducted using sodium dodecyl sulfate-stabilized emulsions, revealed that the Ch/PES membrane achieved oil removal efficiencies exceeding 97% under acidic conditions. This enhancement was attributed to increased hydrophilicity and reduced effective pore size resulting from chitosan swelling. In contrast, under alkaline conditions, the membrane exhibited greater oleophilicity and maintained a relatively stable pore structure, leading to a reduced separation efficiency of 83.8%. Compared to the unmodified PES membrane, the Ch/PES membrane demonstrated significantly improved responsiveness and adaptability to changes in pH, underscoring its potential as a versatile platform for treating oil-contaminated wastewater of varying chemistries. These findings suggest that the Ch/PES membrane offers a promising, sustainable, and efficient solution for advanced oil/water separation applications. Full article

This study proposed a surface modification method, based on petal-shaped micro-pit texture, allowing to solve the problem of significant wear of the stator caused by the oil film rupture in the metal-rubber friction pair of the screw pump under complex conditions in the later stages of oilfield extraction. A geometric model of the petal-shaped micro-pit texture on the stator rubber surface and a mathematical model of the hydrodynamic lubrication flow field based on the Reynolds equation were developed. Computational Fluid Dynamics (CFD) simulations and friction tests were conducted to systematically study the influence of the medium flow direction, texture area ratio, and texture size on the lubrication performance. The obtained results showed that compared with the flow in the x-direction, the load-carrying capacity of the oil film was increased by more than 0.93% when the medium flowed in y-direction, and it reached its optimal value at an area of 10%. When the area ratio reached 60%, the interference effect of the flow field reduced the pressure by 6.98%. The increase of the size of the petals allowed to expand the positive pressure zone and increase the net load-carrying capacity. Furthermore, friction tests demonstrated that the friction coefficient was decreased with the increase of the texture size and increased with the increase of the texture area ratio. The petal-shaped micro-pit texture with size of 350 μm and an area ratio of 10% demonstrated the lowest friction coefficient and highest wear resistance. Full article

Excessive use of antibiotics can lead to antibiotic resistance, posing a significant threat to human health and the environment. Chloramphenicol (CAP), once widely used, has been banned in many regions for over 20 years due to its toxicity. Detecting CAP residues in food products is crucial for regulating safe use and preventing unnecessary antibiotic exposure. Electrochemical sensors are low-cost, sensitive, and easily detect CAP. This paper reviews recent research on electrochemical sensors for CAP detection, with a focus on the materials and fabrication techniques employed. The sensors are evaluated based on key performance parameters, including limit of detection, sensitivity, linear range, selectivity, and the ability to perform simultaneous detection. Specifically, we highlight the use of metal and carbon-based electrode modifications, including gold nanoparticles (AuNPs), nickel–cobalt (Ni-Co) hollow nano boxes, platinum–palladium (Pt-Pd), graphene (Gr), and covalent organic frameworks (COFs), as well as molecularly imprinted polymers (MIPs) such as polyaniline (PANI) and poly(o-phenylenediamine) (P(o-PD)). The mechanisms by which these modifications enhance CAP detection are discussed, including improved conductivity, increased surface-to-volume ratio, and enhanced binding site availability. The reviewed sensors demonstrated promising results, with some exhibiting high selectivity and sensitivity, and the effective detection of CAP in complex sample matrices. This review aims to support the development of next-generation sensors for antibiotic monitoring and contribute to global efforts to combat antibiotic resistance. Full article

This study evaluates and compares the sorption performance of natural zeolite (NZ) and Fe(III)-modified zeolite (FeZ) in removing Cu(II) ions from aqueous solutions, with the goal of assessing their potential for environmental remediation. NZ was modified with Fe(NO₃)₃, NaOH and NaNO₃ solutions to improve its sorption properties. The modification led to a slight decrease in crystallinity (XRD), increase in pore volume (BET), functional groups (FTIR) and negative surface charge (zeta potential), thereby improving the affinity of FeZ towards Cu(II). Batch sorption experiments were conducted to optimize key parameters including pH, solid/liquid ratio (S/L), contact time, and initial Cu(II) concentration. The pH_o and S/L ratio were identified as key factors significantly influencing Cu(II) sorption on both zeolites, with a particularly pronounced effect observed for FeZ. The optimal conditions determined were pH_o = 3–5 for NZ, pH_o = 3 for FeZ, S/L = 10 g/L and a contact time of 600 min. Experimental results confirmed that FeZ has almost twice the sorption capacity for Cu(II) compared to NZ (0.271 mmol/g vs. 0.156 mmol/g), as further supported by elemental analysis, SEM-EDS and mapping analysis of saturated samples. The sorption of Cu(II) followed a mechanism of physical nature driven by ion exchange, dominated by intraparticle diffusion as the rate-controlling step. Leaching of copper-saturated zeolites according to the standard leaching method, DIN 38414 S4, demonstrated the ability of both zeolites to fully retain Cu(II) within their structure over a wide pH range, 4.01 ≤ pH_o ≤ 10.06. These findings highlight the superior performance of FeZ and its potential as an effective material for the remediation of copper-contaminated environments. Full article

Environmental pollution driven by socioeconomic development has intensified the need for advanced and sustainable wastewater treatment technologies. Herein, TiO₂-based photocatalysis emerged as a promising solution due to its oxidative potential, chemical stability, and eco-friendliness but does have unavoidable immobilized recoverability challenges. Therefore, this study explored the challenges and prospects of TiO₂-based photocatalysis for the degradation of emerging contaminants in wastewater. A comprehensive keyword analysis was conducted by using a decade of publications retrieved from Google Scholar, Scopus, and Web of Science (WOS) databases via Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework. From a pool of 518 refined publications, 318 significant keyword occurrences related to TiO₂-based photocatalysis advanced oxidation processes (AOPs) were revealed. The review delved into various types of AOP mechanisms and catalysts and highlighted the synergistic effect of process parameters and magnetization as recoverability potential for TiO₂-based photocatalysts. Furthermore, emerging strategies including surface modifications, doping, and hybrid AOP integrations were discussed to improve photocatalysis performance and industrial scalability. The study underscores the economic opportunity and environmental sustainability of degrading persistent organic pollutants by integrating a TiO₂-based photocatalytic system with a regenerative magnetic field into the water sector. Full article

This study investigates the influence of hybrid filler systems comprising carbon black (CB), mica, and surface-modified mica (SM) on the properties of ethylene–propylene–diene monomer (EPDM)/butadiene rubber (PB) composites. To reduce the environmental issues associated with CB, mica was incorporated as a partial substitute, and its compatibility with the rubber matrix was enhanced through surface modification using ureidopropyltrimethoxysilane (URE). The composites with hybrid filler systems and surface modification were evaluated in terms of curing behavior, crosslink density, mechanical and elastic properties, and dynamic viscoelasticity. Rheological analysis revealed that high mica loadings delayed vulcanization due to reduced thermal conductivity and accelerator adsorption, whereas SM composites maintained comparable curing performance. Swelling tests showed a reduction in crosslink density with increased unmodified mica content, while SM-filled samples improved the network density, confirming enhanced interfacial interaction. Mechanical testing demonstrated that the rubber compounds containing SM exhibited average improvements of 17% in tensile strength and 20% in toughness. In particular, the CB20/SM10 formulation achieved a well-balanced enhancement in tensile strength, elongation at break, and toughness, surpassing the performance of the CB-only system. Furthermore, rebound resilience and Tan δ analyses showed that low SM content reduced energy dissipation and improved elasticity, whereas excessive filler loadings led to increased hysteresis. The compression set results supported the thermal stability and recovery capacity of the SM-containing systems. Overall, the results demonstrated that the hybrid filler system incorporating URE-modified mica significantly enhanced filler dispersion and rubber–filler interaction, offering a sustainable and high-performance solution for elastomer composite applications. Full article

Polypyrrole, which belongs to the conducting polymer family, has demonstrated profound potential in advanced water purification applications due to its inherent electrical conductivity, environmental stability, and tunable surface chemistry. As a sorbent, PPy exhibits high sorption capacity for aquatic contaminants, including heavy metals, pharmaceutical compounds, and their metabolites, as well as synthetic dyes. The removal efficiency is correlated to a complex interaction mechanism involving electrostatic attractions, redox activity, and π–π stacking. Recent advances have expanded the utility by further developing nanostructured PPy-based (nano)composites, which elevate sorption performance by increasing surface area, mechanical integrity, and selective affinity. In addition, its integration into membrane technologies has enabled the design of an effective filtration system with improved selectivity and regeneration capabilities. Moreover, PPy is effective in electrochemical processes of water treatment, including capacitive deionization and electrochemically assisted sorption, opening novel paths towards energy-efficient pollutant removal. The multifunctionality of PPy as a sorbent material highlights its value as an important material for water treatment, with the capability of extended modification tailored for emerging environmental needs revised in this work. Full article