Search Results (2,060)

Aluminum alloy surface microstructures possess functional characteristics such as hydrophilicity/hydrophobicity and anti-icing and have important applications in fields such as aerospace and power systems. In order to improve the filling quality of the microstructure and verify the anti-icing property of the microstructure, this work develops a scheme for achieving large-area hot embossing of anti-icing functional microstructures based on a multi-arc ion-plating mold. Compared with conventional steel, the hardness of the PVD-coated steel increases by 44.7%, the friction coefficient decreases by 66.2%, and the wear resistance is significantly enhanced. The PVD-coated punch-assisted embossing could significantly improve filling properties. While the embossing temperature is 300 °C, the PVD-coated punch-assisted embossing can ensure the complete filling of the micro-array channels. In contrast, under-filling defects occur in conventional hot embossing. Then, a large-area micro-channel specimen of 100 cm² was precisely formed without warping, and the average surface roughness Ra was better than 0.8 µm. The maximum freezing fraction of the micro-array channel was reduced by about 53.2% compared with the planar, and the complete freezing time was delayed by 193.3%. The main reason is that the air layer trapped by the hydrophobic structures hinders heat loss at the solid–liquid interface. Full article

When exposed to high contact pressure and shear conditions, the sliding and/or rolling contact interfaces of moving mechanical systems can experience significant friction and wear losses, thereby impairing their efficiency, reliability, and environmental sustainability. Traditionally, these losses have been minimized using high-performance solid and liquid lubricants or surface engineering techniques like physical and chemical vapor deposition. However, increasingly harsh operating conditions of more advanced mechanical systems (including wind turbines, space mechanisms, electric vehicle drivetrains, etc.) render such traditional methods less effective or impractical over the long term. Looking ahead, an emerging and complementary solution could be tribocatalysis, a process that spontaneously triggers the formation of nanocarbon-based tribofilms in situ and on demand at lubricated interfaces, significantly reducing friction and wear even without the use of high-performance additives. These films often comprise a wide range of amorphous or disordered carbons, crystalline graphite, graphene, nano-onions, nanotubes, and other carbon nanostructures known for their outstanding friction and wear properties under the most demanding tribological conditions. This review highlights recent advances in understanding the underlying mechanisms involved in forming these carbon-based tribofilms, along with their potential applications in real-world mechanical systems. These examples underscore the scientific significance and industrial potential of tribocatalysis in further enhancing the efficiency, reliability, and environmental sustainability of future mechanical systems. Full article

SARS-CoV-2 variants have demonstrated distinct epidemiological patterns and clinical presentations throughout the COVID-19 pandemic. Understanding variant-specific differences at the respiratory epithelium is crucial for understanding their pathogenesis. Here, we utilized human nasal organoid air–liquid interface (HNO-ALI) cell cultures to compare the viral replication kinetics, innate immune response, and epithelial damage of six different strains of SARS-CoV-2 (B.1.2, WA, Alpha, Beta, Delta, and Omicron). All variants replicated efficiently in HNO-ALIs, but with distinct replication kinetic patterns. The Delta variant exhibited delayed replication kinetics, achieving a steady state at 6 days post-infection compared to 3 days for other variants. Cytokine analysis revealed robust pro-inflammatory and chemoattractant responses (IL-6, IL-8, IP-10, CXCL9, and CXCL11) in WA1, Alpha, Beta, and Omicron infections, while Delta significantly dampened the innate immune response, with no significant induction of IL-6, IP-10, CXCL9, or CXCL11. Immunofluorescence and H&E analysis showed that all variants caused significant ciliary damage, though WA1 and Delta demonstrated less destruction at early time points (3 days post-infection). Together, these data show that, in our HNO-ALI model, the Delta variant employs a distinct “stealth” strategy characterized by delayed replication kinetics and epithelial cell innate immune evasion when compared to other variants of SARS-CoV-2, potentially explaining a mechanism that the Delta variant can use for its enhanced transmissibility and virulence observed clinically. Our findings demonstrate that variant-specific differences at the respiratory epithelium could explain some of the distinct clinical presentations and highlight the utility of the HNO-ALI system for the rapid assessment of emerging variants. Full article

The urinary bladder is a primary target organ for environmental toxicants such as arsenic. The objects of this study were two-fold. First, we constructed a novel 3D urinary bladder mucosa model (3D-UBMM) composed of an overlying epithelium and a supporting subepithelial layer. Primary human bladder urothelial and fibroblast cells were immortalized by introducing the human CDK4^R24C and TERT genes. The construction of the 3D-UBMM involved incorporating immortalized fibroblast cells into a collagen raft, while immortalized urothelial cells were cultured at the air-liquid interface. This 3D-UBMM closely resembles the human bladder epithelium in terms of morphology and marker protein expression, including uroplakin 1b, P63, and cytokeratin 5. Second, using the 3D-UBMM we investigated the cytotoxicity of sodium arsenite (iAs^III) and dimethylarsenic acid (DMA^V). Exposure to iAs^III and DMA^V resulted in increased urothelial necrosis, increased γ-H2AX-positive cells, and reduced P63-positive cells, all in a dose–response manner. These findings affirm that this novel 3D-UBMM resembles the human bladder epithelium and offers a practical in vitro model for evaluating bladder toxicants and carcinogens, identifying mechanisms of carcinogenesis, and supporting hazard identification and risk assessment. Full article

This work aims to study the effect of the bulk rheology of a complex system on the apparent interfacial viscoelastic response of a rising oil droplet of a paraffinic oil (Indopol) undergoing sinusoidal volume dilatations insidean aqueous phase containing a hydrogel. The modulation of the interfacial viscoelasticity is obtained using Span 80 surfactant or fumed silica nanoparticles. The rheology of the continuous phase is tuned by adding 3 to 5 g/L of κ-carrageenan (KC) to switch the continuous aqueous phase from a liquid to a gel state at 15 °C. When KC is liquid, the presence of Span 80 or nanoparticles at the liquid/liquid interface increases the apparent interfacial elastic modulus. However, when KC becomes a weak gel, the apparent interfacial elastic modulus depends on the nature of the surface-active agents. Indeed, if the presence of silica hard nanoparticles enhances the apparent elasticity of the interface, adding Span 80 weakens the apparent elasticity of the interface. These trends are discussed in terms of the localization of the deformation and slippage at the interfaces. Full article

Background: While rhinoviruses (RVs) typically cause mild respiratory infections, their persistence during the SARS-CoV-2 pandemic, particularly in Hong Kong’s strict zero-coronavirus disease 2019 policy, revealed unexpected epidemiological patterns. Two distinct RV surges emerged despite stringent public health measures, suggesting unique transmission advantages among circulating strains. We hypothesised that RV persistence during pandemic restrictions reflected strain-specific adaptations in respiratory tract replication efficiency and/or immune evasion. Methods: We analysed RV genotypes and conducted blinded clinical severity assessment for 96 paediatric hospitalisations during 2020–2021 outbreaks, compared with 180 age- and sex-matched control subjects from the corresponding weeks in pre-pandemic years (2018–2019). RV isolates from 2020 to 2021 outbreaks were characterised for their replication competence and transcriptomic responses in primary human nasal epithelial cell (HNEC) and environmental stability assays, using RV-A16 and RV-A1B as controls. Result: Minor group genotypes RV-A47 and RV-A49 were overrepresented during these two outbreaks. RV-A49 exhibited comparable replication efficiency to RV-A16 but induced significantly stronger transcriptomic responses, notably enhanced TNF and IL-1 signalling, in HNECs, alongside robust replication competence. Our data also suggests the association of RV-A49 with tachypnoea in 2021, particularly in younger males, though limited by a small sample size and single-centre design. Conclusion: The predominance of RV-A49 in hospitalised children during the SARS-CoV-2 pandemic potentially driven by its replication competence in HNECs and its capacity to enhanced inflammatory responses. The result is hypothesis-generating, warranting further studies with historical strains and broader populations to confirm strain-specific severity. Full article

Due to their excellent mechanical stability, chemical stability, and environmentally friendly properties, ceramic materials have received extensive attention for years. Meanwhile, ionic liquids (ILs) have been found to effectively enhance tribological properties when applied as lubricants, which has become a distinctive example of their wide exploration. Here, three novel proton-type ionic liquids containing different polar groups were designed and synthesized as pure lubricants for use on different ceramic friction couples (silicon nitride–silicon nitride, silicon nitride–silicon carbide, and silicon nitride–zirconium oxide contacts), and their lubrication effect was evident. The results indicate that the adsorption behavior and frictional characteristics of different polar groups on a ceramic friction interface differ, largely depending on tribochemical reactions and the formation of a double electric layer on the interface between the ILs and ceramic substrates, without obvious corrosion during sliding. The friction coefficient is reduced by more than 80%, and this excellent anti-friction effect demonstrates that the constructed ionic liquid–ceramic interface tribological system shows good application potential. Based on the analyses of SEM, EDS, and XPS, the tribochemical reaction on the sliding asperity and the film-forming effect were identified as the dominant lubrication mechanisms. Here, the high lubricity and anti-wear performance of ILs containing phosphorus elements on different ceramic contacts is emphasized, enriching the promising application of high-performance ILs for macroscale, high-efficiency lubrication and low wear, which is of significance for engineering and practical applications. Full article

In the present study three composite materials based on iron in combination with bismuth, copper or lithium carbonates FeNO₃@Li₂CO₃ (SFL), FeNO₃@CuCO₃ (SFC), and FeNO₃@(BiO)₂CO₃ (SFB) were synthesized by coprecipitation. The purpose was to obtain materials that possess targeted adsorbent properties for the recovery of silver ions from aqueous solutions. After synthesis, to emphasize the adsorptive qualities of materials for the recovery of silver ions, the synthesized composite materials, as well as those doped with silver ions following the adsorption process (SFL-Ag, SFC-Ag, and SFB-Ag), were characterized and several adsorption-specific parameters were examined, including temperature, contact time, pH, adsorbent dose, and the initial concentration of silver ions in solution. Subsequently, the ideal adsorption conditions were determined to be as follows: pH > 4, contact time 60 min, temperature 298 K, and solid–liquid ratio (S–L) of 0.1 g of adsorbent to 25 mL of Ag (I) solution for all three materials. The Langmuir model properly fits the experimental equilibrium data of the adsorption process; however, the Ho–McKay model closely represents the adsorption kinetics. The maximum adsorption capacities of the materials, 19.7 mg Ag(I)/g for SFC, 19.3 mg Ag(I)/g for SFB, and 19.9 mg Ag(I)/g for SFL, are comparable. The adsorption mechanism is physical in nature, as evidenced by the activation energies of 1.6 kJ/mol for SFC, 4.15 kJ/mol for SFB, and 1.32 kJ/mol for SFL. The highest Ag(I) concentration used for doping all three materials in the study was 150 mg Ag(I)/L. The process is endothermic, spontaneous, and takes place at the interface between the adsorbent and the adsorbate, according to thermodynamic theory. Subsequently, the antimicrobial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans microorganisms was evaluated by rate of inhibition assessment. The SFC-Ag material showed a percentage of 100% inhibition with respect to the positive control for each microorganism. All synthetized materials have better efficiency as antifungal agents. Full article

This study develops an incompressible two-phase flow solver based on the open-source OpenFOAM platform, employing the volume-of-fluid (VOF) method to track the gas–liquid interface and utilizing the MULES algorithm to suppress numerical diffusion. This study provides a comprehensive investigation of the spreading dynamics of droplet pairs near walls, along with the presentation of a corresponding mathematical model. The numerical model is validated through a two-dimensional axisymmetric computational domain, demonstrating grid independence and confirming its reliability by comparing simulation results with experimental data in predicting drConfirmedoplet collision, spreading, and deformation dynamics. The study particularly investigates the influence of surface wettability on droplet impact dynamics, revealing that increased contact angle enhances droplet retraction height, leading to complete rebound on superhydrophobic surfaces. Finally, a mathematical model is presented to describe the relationship between spreading length, contact angle, and Weber number, and the study proves its accuracy. Analysis under logarithmic coordinates reveals that the contact angle exerts a significant influence on spreading length, while a constant contact angle condition yields a slight monotonic increase in spreading length with the Weber number. These findings provide an effective numerical and mathematical tool for analyzing the spreading dynamics of droplet pairs. Full article

Mechanical activation significantly enhances the leaching of chalcopyrite, a process that is fundamentally electrochemical in nature. Thus, a comprehensive understanding of its impact on the electrochemical behavior of chalcopyrite in leaching systems is crucial. This study examines the effect of mechanical activation on the electrochemical and semiconductor properties of chalcopyrite in H₂SO₄ solutions containing Fe²⁺ or/and Fe³⁺ at pH = 1.5. Mechanical activation was carried out using a planetary ball mill at 700 rpm for durations ranging from 0 to 2.5 h to reduce particle size and induce lattice distortion, thereby increasing its electrochemical activity. In iron-containing electrolytes, mechanically activated chalcopyrite is more readily reduced, releasing Fe²⁺ and leading to a higher surface concentration of Fe²⁺, which consequently increases the diffusion coefficient at the solid–liquid interface. Mott–Schottky analysis revealed a decrease in flat band potentials (from 261.7 mV to 131.2 mV in 0.1 mol/L Fe³⁺ after 1.0 h of activation) and an elevation in Fermi levels. As a result, mechanical activation markedly accelerates the corrosion rate of chalcopyrite in ferric solutions—the corrosion current increased from 40.27 µA to 70.71 µA in 0.1 mol/L Fe³⁺ after 1.0 h of activation. These findings provide valuable insights for developing strategies to enhance mineral dissolution, and advance the hydrometallurgical processing of chalcopyrite. Full article

Hexagonal boron nitride (h-BN) possesses a unique combination of a wide bandgap, high thermal conductivity, and chemical inertness, making it a key insulating and thermal management material for advanced electronics and nanocomposites. However, its intrinsic hydrophobicity and strong interlayer van der Waals forces severely limit exfoliation efficiency and dispersion stability, particularly in scalable liquid-phase processes. Here, we report a synergistic exfoliation strategy that integrates acid-induced hydroxylation with gallium (Ga) intercalation to achieve high-yield (>80%) production of ultrathin (<4 nm) hydrophilic h-BN nanosheets. Hydroxylation introduces abundant -OH groups, expanding interlayer spacing and significantly increasing surface polarity, while Ga intercalation leverages its native Ga₂O₃ shell to form strong interfacial interactions with hydroxylated basal planes. This oxide-mediated adhesion facilitates efficient layer separation under mild sonication, yielding nanosheets with well-preserved lateral dimensions and exceptional dispersion stability in polar solvents. Comprehensive characterization confirms the sequential chemical and structural modifications, revealing the crucial roles of hydroxylation-induced activation and Ga₂O₃ assisted wettability enhancement. This combined chemical activation–soft metallic intercalation approach provides a scalable, solution-processable route to high-quality h-BN nanosheets, opening new opportunities for their integration into dielectric, thermal interface, and multifunctional composite systems. Full article

Ti150 has potential applications in aeroengine components. However, the lack of research on its flame resistance, combustion behavior, and mechanisms makes it difficult to assess the risk of “titanium fire” and leaves fire protection design without theoretical support. This study aimed to determine the combustion resistance of Ti150 and elucidate its combustion behavior and mechanisms to address these issues. Through comparative Promoted Ignition-Combustion (PIC) tests between Ti150 and TC11 alloys, microstructural characterization, and thermodynamic/kinetic analyses, the following conclusions were drawn. Ti150 alloy exhibited a higher critical oxygen pressure and a higher ignition temperature but a significantly faster burning velocity, compared with TC11 alloy. The relationship between pressure and ignition temperature was in good agreement with the modified Frank-Kamenetskii ignition model. The ignition activation energy of Ti150 alloy was determined to be 118.41 kJ/mol, which was approximately 21% higher than that of TC11 alloy (97.72 kJ/mol). Moreover, post-combustion microstructural observations of Ti150 alloy revealed a higher oxygen content in the melting zone and an enrichment of Zr at the solid–liquid interface, both of which contribute to the higher burning velocity of Ti150 alloy compared with TC11 alloy. Full article

Gallium-based liquid metal is corrosive to steel alloys, forming FeGa₃ surface films which can potentially be applied as a solid lubricant to enhance wear resistance and mitigate liquid metal-induced corrosion. However, the characteristics of these films remain insufficiently explored. In this study, Ga-In-Sn alloy was ultrasonically soldered onto annealed and decarburised substrates, followed by heating in a vacuum chamber to form a 30 μm thick FeGa₃ reaction layer. The film on the annealed samples with an alpha-ferrite microstructure exhibited high porosity and a surface roughness of 1.97 Ra. In contrast, the film on the decarburised samples with a ferritic microstructure showed minimal porosity and a lower surface roughness of 1.29 Ra. Nanoindentation tests revealed Young modulus values of 231 GPa and 242 GPa and hardness values of 11.4 GPa and 12.7 GPa for the annealed and decarburised samples, respectively. The high porosity in the annealed samples is attributed to the suppression of FeGa₃ formation in regions containing chromium carbides. Shear stress for fracture, measured by microcantilever tests at the interface between the substrate and the inner matrix of the surface film, showed lower fracture shear stress in the annealed sample, attributed to the presence of larger pores within its microstructure. Full article

Biomass reforming under mild conditions for synergistic hydrogen production, driven by renewable solar energy, has rapidly emerged as a promising strategy that not only enables the efficient reutilization of biomass but also facilitates the generation of high-purity hydrogen. In this work, ZnCdS (ZCS) nanoparticles and CoWO₄ (CW) nanocrystals were assembled via a solvothermal method to construct a ZCS/CW S-type heterojunction composite. The resultant materials’ physicochemical characteristics were methodically described. With lignin model compounds (PP-ol) and sodium lignosulfonate as substrates, the ZnCdS/CoWO₄-10% catalyst demonstrated a significant generation of hydrogen activity, producing hydrogen at rates of 223.30 μmol·g⁻¹·h⁻¹ and 140.28 μmol·g⁻¹·h⁻¹, respectively, according to experimental results. The formation of heterojunctions endows composite photocatalysts with higher hydrogen evolution rates compared to single-component catalysts. This is attributed to energy band bending at the interface of the heterojunction, which facilitates efficient charge separation while maintaining strong redox capabilities. High-value compounds like phenol and acetophenone were formed when the oxidation products in the post-reaction lignin model compound solution were subsequently analyzed using high-performance liquid chromatography. Additionally, a convincing mechanism for the catalytic reaction was suggested. It is expected that this study will offer a viable route for the creation of effective photocatalytic materials, high-value organic waste transformation, and sustainable hydrogen production. Full article

Bronze-steel bimetallic structures are structural components finding a growing application in industrial sectors such as aerospace, power generation, and machinery. Recent legislation on green economy and sustainable manufacturing is boosting industry to implement innovative manufacturing processes and new metal alloys capable of lowering environmental footprint by avoiding toxic substances. Laser Metal Deposition is a cost-effective Additive Manufacturing technique for producing bimetallic components by limiting material waste and reducing energy consumption. In this research work, the influence of the main LMD process parameters on the final quality of CuSn₁₁Bi₃ coatings on C45 surfaces is analyzed. The Cu-based powder is specifically designed and developed to reduce environmental pollution and increase worker safety by avoiding the use of hazardous chemical elements. The performed observations demonstrate that high-density (99.90%) and crack-free clads are feasible by preventing melt pool dilution zones. Cu diffusion into the C45 substrate deteriorates the structural integrity at the clad-substrate interface by inducing liquid metal embrittlement cracking, whereas steel diffusion into the as-deposited clad promotes crack propagation. High-density (up to 99.97%) and crack-free CuSn₁₁Bi₃ coatings are achieved by using low specific energies (from 17 J/mm² to 40 J/mm²) and reducing the Oxygen content during sample manufacturing up to 0.02%. Full article