Search Results (7,121)

Hydrophobicity and hydrophilicity are incompatible in the sense that a single substrate cannot exhibit both characteristics simultaneously. On a hydrophobic substrate, for example, a macroscopic droplet always exhibits a morphology with a contact angle higher than 90°, never lower than 90°. In this paper, we theoretically demonstrate the possibility that a nanoscale droplet can exhibit a contact angle lower than 90° on the same hydrophobic substrate. To demonstrate this, we analyze the morphology and contact angle of a sessile droplet on smooth flat substrates, taking into account disjoining pressure of Lennard–Jones type. By constraining the two-dimensional cylindrical droplet and minimizing the free-energy functional, we derive a formula to determine the droplet’s morphology and the boundary between hydrophilic and hydrophobic contact angles for finite-sized droplets. Using this formulation, we reconsider the formula for the macroscopic contact angle, known as the Derjaguin–Frumkin formula. By utilizing a simple disjoining pressure model, we find that the calculated contact angle at the nanoscale is always smaller than the macroscopic contact angle determined by the Derjaguin–Frumkin formula. Consequently, the wettability (hydrophilicity/hydrophobicity) differs at the nanoscale compared to the macroscale. We further discuss the implication of our results on the size-dependent contact angle and line tension at the nanoscale. Full article

The development of interface-engineered, multifunctional nanostructured materials with controllable surface and magnetic properties remains a critical challenge in wastewater treatment and environmental remediation. In this work, a novel GO–CoFe₂O₄–Silicone Magnetic Sponge was successfully fabricated through the integration of graphene oxide and CoFe₂O₄ magnetic nanoparticles within a silicone-modified porous sponge matrix. The resulting material combines superhydrophobicity, oleophilicity, high adsorption capacity, and magnetic responsiveness in a single architecture. The prepared sponge exhibited a high water contact angle of 161.5°, confirming its superhydrophobic nature, while maintaining excellent structural integrity during repeated use. Vibrating sample magnetometry revealed clear ferrimagnetic behavior, enabling rapid magnetic manipulation and efficient recovery of the sponge from aqueous media. The GO–CoFe₂O₄–Silicone Magnetic Sponge demonstrated strong adsorption performance toward a wide range of oils and organic solvents, including chloroform, olive oil, toluene, ethanol, acetone, gasoline, and hexane, with adsorption capacities remaining stable over multiple cycles. Furthermore, the sponge showed outstanding separation efficiency exceeding 98.3% for various oil/water and organic solvent/water mixtures, both in batch and continuous vacuum-assisted separation systems. The adsorption capacity and separation efficiency were retained after repeated adsorption–desorption cycles, indicating excellent reusability and durability. Owing to its synergistic combination of surface chemistry, porous structure, and magnetic functionality, the GO–CoFe₂O₄–Silicone Magnetic Sponge represents a promising candidate for practical applications in oil spill cleanup and wastewater treatment. Full article

Oily substances (oils, greases, lubricants, etc.) are among the most persistent pollutants for water. They mix with water to form emulsions that contaminate large volumes. Therefore, this project evaluated the use of porous systems (polyurethane foam) modified with polydimethylsiloxane-modified silica (SiO₂/DMS) hybrid ceramics as filtration membranes at the laboratory scale for vegetable oil. The polyurethane foam was modified using sol solutions with various SiO₂/PDMS ratios obtained via the sol–gel method. Tetraethyl-orthosilicate (TEOS) was used as the silica precursor. Three different polydimethylsiloxane chains were employed as the organic fragment: polydimethylsiloxane hydroxyl terminated (DMS-CH₃), aminopropyl-terminated polydimethylsiloxane (DMS-N), and copolymer polydiphenylsiloxane-polydimethylsiloxane hydroxyl terminated (PDS). The siloxane chain was added at a concentration of 20–40% w/w. The modification of the porous system was determined using different characterization techniques, including infrared spectroscopy, which was used to observe the main functional groups. Optical microscopy and SEM were used to identify the hybrid ceramic deposited into the pore structure of the polyurethane sponge. Contact angle measurements revealed the hydrophobic character of the modified material. The removal capacity was evaluated by using vegetable oil as a representative oily contaminant, with values ranging from 43.42 to 96.78 g of oil per gram of adsorbent. In the case of gasoline, removal capacities between 27 and 54 g were observed. This study demonstrated the influence of hydrophobicity on vegetable oil removal, confirming that higher hydrophobicity leads to greater adsorption capacity. Nevertheless, the use of a viscous contaminant introduced challenges in the extraction process from the PS/SiO₂-DMS system. Despite this limitation, the material maintained adequate removal performance for up to five reuse cycles. On the other hand, the removal capacity depends on the amount of polysiloxane chain in the ceramic, as well as the functional group, exhibiting the following behavior: DMS-N < DMS-CH₃ < PDS. This study demonstrates that hydrophobicity is a key property for enhancing the removal capacity of oily substances. Moreover, the control of intermolecular interactions further strengthens this effect, as evidenced in the PS/SiO₂–PDS system. Full article

Composites based on rPE and OPEFB waste are considered sustainable materials. However, their performance is limited by hydrophobic–hydrophilic incompatibility, which weakens interfacial adhesion. This study investigated the atmospheric-pressure air plasma treatment of rPE to enhance its compatibility with OPEFB fibers and evaluated its role as a compatibilizer. Atmospheric plasma treatment for 120 s introduced oxygen-containing groups onto the rPE surface, as evidenced by C-O and OH peaks in the FTIR spectra and the higher O/C ratio in the XPS analysis. Consequently, the water contact angle decreased, reducing the difference in surface tension between rPE and OPEFB from 45.61% to 7.80%. Composites containing 20 wt.% OPEFB were fabricated by varying the proportion of untreated rPE with p-rPE. All p-rPE-based composites exhibited fewer interfacial voids than untreated rPE composites, indicating improved fiber–matrix adhesion. The tensile strength and elastic modulus increased with the p-rPE content, whereas the elongation at break remained higher than that of the untreated composite. Therefore, p-rPE shows potential as a compatibilizer, enabling agricultural and plastic waste value enhancement. Full article

Intervertebral disk pathology, including disk herniation and degeneration, is a major contributor to chronic low back pain, and when conservative treatment fails, surgical management often involves discectomy-based procedures that leave residual annulus fibrosus (AF) defects associated with reherniation and progressive degeneration. These limitations have motivated interest in regenerative strategies using biomaterial scaffolds; however, reproducing the hierarchical, angle-ply architecture of the AF remains challenging. Here, we present a single-step extrusion-based 3D-printing approach to fabricate polycaprolactone (PCL) scaffolds with aligned microscale surface grooves that promote AF-like organization. Patterned nozzles with circumferential peaks generated uniaxial concave microgrooves (10–17 µm wide) directly during printing, enabling formation of multilamellar angle-ply constructs. Human bone marrow-derived mesenchymal stem cells cultured on patterned scaffolds aligned longitudinally within concave grooves, forming end-to-end arrays that guided extracellular matrix deposition. Gene expression analysis showed that topographical cues governed cellular organization without significantly altering gene expression profiles, while TGF-β3 supplementation upregulated outer AF-associated markers, including COL1, COL12, SFRP2, MKX, MCAM, and SCX. TAGLN expression increased specifically on patterned scaffolds in the absence of TGF-β3, indicating an association between microgroove-guided cellular organization and TAGLN expression, warranting further investigation into potential tension-related mechanisms. This novel single-step extrusion-printing approach leverages custom nozzle geometry to impart concave microgrooves, facilitating scalable fabrication of multilamellar angle-ply scaffolds that induce aligned cellular organization and support potential applications in annulus fibrosus repair, as well as mechanobiological studies of anisotropic musculoskeletal tissues. Full article

This study investigates amplified hydraulic braking systems employed in high-performance motorsport applications, utilizing wedge mechanisms for self-energization. An analytical expression for the gain coefficient is derived from a simplified equilibrium analysis of the wedge-shaped pad, capturing the nonlinear dependency on both wedge angle and effective mean disc-pad friction. A previously validated coupled thermoelastic model for carbon-carbon (C/C) braking systems—developed in Dymola and Modelica using the finite volume method (FVM) and an analytical local friction formulation—is here adapted to wedge-amplified braking systems, with the aim of providing performance assessment during the design phase of new calipers at reduced computational cost compared to coupled thermoelastic finite element method (FEM) models. Several caliper configurations featuring different wedge angles are tested experimentally on a dynamometer. A reduction in the effective friction coefficient at high mean effective contact pressure—induced by pronounced wedge angles and reduced pad areas—is observed. To validate the thermoelastic model, simulated braking torque and disc surface temperature are compared against bench data. The model shows satisfactory predictive capability under various operating conditions and test cycles, with mean error indices on peak torque prediction below $5\%$ for the majority of the simulated cases. Finally, the validated model is used to virtually assess the performance of a new caliper prototype prior to its manufacturing and testing. Full article

Aiming at the challenge of simultaneously controlling ride comfort and wheel grounding performance for mining dump trucks, this paper proposes a multi-dimensional synergistic optimization control (MDSOC) strategy based on model predictive control (MPC) for active hydro-pneumatic suspension. First, an accurate hydro-pneumatic suspension and hinged mining truck full-vehicle-dynamics model is established, and the model accuracy is validated through actual vehicle testing. Subsequently, an MDSOC-MPC for active hydro-pneumatic suspension is constructed to minimize the mean square root of the three-axis acceleration of the body, pitch angle, roll angle, and wheel dynamic tire load. Comparative analysis is performed with traditional single-MPC longitudinal, lateral, and vertical control, and the simulation results showed: under emergency braking conditions, the root mean square (RMS) value of the pitch angle is reduced by 18.2%; under single and double-shift conditions, the RMS values of the roll angle are reduced by 40.4% and 30%, respectively; under D-class random road, the RMS values of the longitudinal, lateral, and vertical body acceleration are significantly reduced by 22%, 21.5%, and 21.2%, respectively, while the RMS values of pitch angle and roll angle are reduced by 22.5%, and 20.2%, respectively, systematically improving riding comfort, vehicle wheel contact, and driving safety. This study provides a theoretical basis and feasible engineering methods for the active control of hydro-pneumatic suspension systems in heavy engineering vehicles. Full article

Superhydrophobic materials have clear potential for mitigating rain/humidity-induced damage to cultural heritage. In the present study, the wetting properties of Paraloid B72 were tailored to achieve superhydrophobicity by incorporating modified calcium carbonate (CaCO₃) nanoparticles (NPs). B72 is a well-established conservation product while CaCO₃ is chemically compatible with calcareous materials commonly found in cultural heritage buildings and objects. Initially, the wettabilities of CaCO₃ NPs, functionalised with caproic (C6), caprylic (C8), lauric (C12), myristic (C14), palmitic (C16), and stearic (C18) acid, were evaluated by measuring water contact angles (CAs) on NP pellets. For NPs with short hydrocarbon chains, CA increased with chain length, from 66.3° for CaCO₃-C6 to 118.0° for CaCO₃-C12 NPs. For NPs with longer chains, CA remained stable and around 118°. Based on these results, CaCO₃-C12 NPs were selected for further investigation and subjected to transmission electron microscopy analysis, which revealed chain-like agglomerates of aggregated nanocrystallites (5–10 nm) forming 40–150 nm polycrystalline NPs. Scanning transmission electron microscopy combined with elemental mapping revealed a homogeneous distribution of Ca, C, and O within the NPs. Next, CaCO₃-C12 NPs were dispersed in B72 solutions and sprayed onto limestone, which was employed as a model calcite-rich substrate. At optimal NP concentration, the resulting composite coating exhibited superhydrophobicity (CA > 150°), while it induced minimal colour alteration to limestone and effective resistance to capillary water absorption. The fluorine-free coating also demonstrated good durability against UV exposure, drop impact, salt attack, freeze–thaw cycles, tape peeling, drop pH variations, and thermal treatment. Full article

For decades, zirconia- and ceramic-based materials have dominated dental crown fabrication due to their durability and aesthetic appeal. However, a fundamental shift is occurring as polymeric alternatives emerge with notable advantages: better adhesive bonding, versatile aesthetics, lower costs, and a lighter weight. The advances in polymer chemistry and additive manufacturing have significantly impacted prosthodontics, allowing the rapid creation of highly customized, patient-specific restorations with a precision previously impossible (achieved through advanced Computer-Aided Design software and standardized 3D-printing equipment) with traditional methods. This review provides a detailed analysis of 3D-printed polymeric dental crowns from various angles. It explores the materials science behind different polymers, compares manufacturing methods, and evaluates the mechanical performance and biocompatibility. Despite the progress, polymeric materials still fall short of matching the mechanical properties of advanced ceramics, especially in compressive strength and wear resistance. Moreover, there is limited long-term clinical data over five to ten years. The lack of standardized testing protocols complicates cross-study comparisons, and the regulatory pathways for patient-specific 3D-printed devices are still developing, creating uncertainty for manufacturers and clinicians. The future prospective looks promising in many ways such as innovations like four-dimensional printing, where materials respond dynamically to environmental stimuli, which could enable crowns that adapt to changing oral conditions. Nanocomposites with functionalized nanoparticles might enhance mechanical properties while maintaining printability. AI-driven design optimization could automate and improve the crown morphology, occlusal contacts, and fit. Incorporating bioactive materials could turn crowns into active therapeutic devices that promote remineralization and combat bacterial colonization. This review summarizes the current knowledge, highlights the key gaps, and suggests steps toward establishing polymeric 3D-printed crowns as viable long-term alternatives capable of competing with or surpassing traditional ceramic options. Full article

In this study, by using four different silicon sources obtained from Konya, Turkey, and its surroundings and employing the sol–gel method, we aim to synthesize silica-based aerogel, characterize it, and improve the use of the innovative building material as a thermal insulator in architectural applications. In this direction, silica aerogel production was carried out using four different starting materials (commercial casting sand, waste casting sand, radiolarite, and quartz) and five different pH values (2–4–6–8–9) by the sol–gel method. The produced silica aerogels were subjected to a surface modification process with Trimethylchlorosilane (TMCS), a modification chemical, and then superhydrophobic silica aerogel powder was obtained. In terms of characterization of the obtained final silica aerogels, XRF, XRD, ICP-OES, density study, FT-IR, BET, FESEM, and contact angle studies were performed. In terms of application of the architectural building material, plasterboard experimental samples were produced using low reinforcement rates (0 wt%, 0.5 wt%, 1 wt%, 2 wt%, and 5 wt%) of silica aerogel. To determine the mechanical and physical properties of the produced silica-aerogel-reinforced plasterboard samples, three-point bend (flexural) strength, compressive strength, thermal conductivity, and water absorption tests were applied. After surface modification, the lowest density value was 0.340 g/cm³, the highest surface area was 311.161 m²/g, and the lowest thermal conductivity coefficient was 0.29 W/mK in silica aerogel material containing radiolarite. In addition to high reinforcement contents in the literature, when it comes to silica aerogel low-reinforcement material and mechanical properties, it can be stated that increasing reinforcement contents negatively affects the mechanical behavior of the material after a certain value. Full article

Modulating surface characteristics via metal ions has proven to be a successful approach to enhance the flotation efficiency of carbonates. Consequently, this research thoroughly examines how ferrous ions (Fe²⁺) influence the selective separation of rhodochrosite from calcite. Flotation experiments revealed that at pH 9.0, Fe²⁺ strongly depressed calcite flotation (recovery < 20%) while exerting a negligible influence on the floatability of rhodochrosite (recovery > 75%), enabling effective selective separation. To elucidate the underlying mechanism, contact angle measurements, zeta potential analysis, ToF-SIMS, SEM-EDS, XPS and Visual MINTEQ solution chemistry calculations were employed to characterize mineral surface properties. The results demonstrate that Fe²⁺ undergoes chemisorption onto the calcite surface, inducing the formation of a dense, uniform iron hydroxide layer. This layer creates a stable hydrophilic barrier that inhibits collector adsorption. In contrast, only a thin, discontinuous layer forms on the rhodochrosite surface, which is insufficient to hinder collector interaction. These findings reveal the intrinsic mechanism of selective interfacial regulation by ferrous ions, providing a new theoretical basis for the flotation separation of refractory carbonate minerals. Full article

To investigate the motion mechanism and kinetic energy loss characteristics of wheat particles in a horizontal–vertical upward bend pipe, different curvature radii, gas velocities, and particle mass flow rates are used to study changes in particle velocity, the inter-particle contact force, and the particle–wall contact force in this study. The results indicate that larger curvature radii weaken the inter-particle contact force. The velocity difference between particles inside and outside of the bend first increases and then decreases at the elbow. Increasing the gas velocity increases the particle velocity and the particle–wall contact force. It also enlarges the velocity gap between the inner and outer particles of the bend, while weakening the inter-particle contact force. With an increase in the mass flow rate, the particle–wall contact force gradually rises at 0–30° of the bend, and then gradually falls at 30–90°. Meanwhile, the inter-particle contact force is enhanced. A higher gas velocity leads to a greater loss of particle kinetic energy caused by collisions. The velocity difference exhibited by particles on the inner and outer sides of the bend remains basically unchanged. The maximum inter-particle and particle–wall contact force is around the 30° bend angle. Full article

The replacement of petroleum-based plastics with sustainable and biodegradable materials remains a critical challenge for food packaging and biomedical applications. Gelatin is an attractive natural biopolymer for film fabrication; however, its inherent brittleness, moisture sensitivity, and limited structural stability restrict practical use. In this work, for the first time, low-power direct-probe ultrasonication is introduced as a green and additive-free strategy to regulate molecular organization and enhance the performance of gelatin–glycerol composite films. Systematic variation in ultrasonic power and treatment duration revealed a strong dependence of film structure and properties on processing conditions. Low-power ultrasonication (20 W) promoted gelatin–glycerol interactions, induced a transition from loosely organized molecular arrangements to helix-like molecular packing at the nanometer scale, and produced smooth, compact microscale surface morphologies. As a result, these films exhibited enhanced hydrophilicity, reduced surface defects, and improved thermal stability. In contrast, high-power ultrasonication generated excessive cavitation, leading to large-scale porous structures and diminished thermal and surface performance. Therefore, this work identifies a distinct low-power ultrasonic window that enables controlled molecular reorganization and hierarchical structure formation in gelatin–glycerol systems. Structural and physicochemical analyses using SEM, FTIR, XRD, water contact angle measurements, and thermogravimetric analysis collectively elucidate the ultrasound-driven structure–property relationships within the gelatin–glycerol matrix. Overall, this study demonstrates that controlled ultrasonication enables precise tuning of gelatin-based film architecture and properties, offering a scalable and environmentally friendly route to high-performance biodegradable materials for sustainable packaging and biomedical applications. Full article

Lignin, the second-most-abundant polymer on Earth, has attracted attention for its value-added applications. Colloidal lignin particles can overcome handling and compatibility issues, offer antioxidant, antimicrobial, and UV-protective properties, and serve as Pickering stabilizers. Plant extracts rich in bioactive compounds, such as polyphenols and flavonoids (e.g., quercetin), can further enhance lignin-based formulations. In this context, colloidal lignin–quercetin particles (CLQPs) were produced for the first time via antisolvent precipitation and used as Pickering emulsion stabilizers. CLQP dispersions (30 g/L) were prepared by solubilizing lignin and quercetin in 80% (v/v) aqueous acetone solution, followed by precipitation with a pH 8 buffer. A quercetin content of 50% (w/w) (CLQP-50) resulted in predominantly round-shaped lignin–quercetin particles (<1 µm) with a small fraction of quercetin crystals. Both structures contributed to emulsion stabilization, as evidenced by confocal microscopy, a three-phase contact angle of 91.6 ± 0.1°, and a zeta potential of −52.8 ± 2.7 mV. CLQP-50 successfully stabilized Pickering emulsions at a 60/40 oil/water ratio, showing high physical stability (stability index 0.01) and shear-thinning behavior with gel-like consistency. These findings demonstrate the pioneering development of lignin–quercetin hybrid colloidal particles as sustainable and functional Pickering stabilizers, opening new opportunities for advanced cosmetic and pharmaceutical formulations. Full article

Moisture content varies continuously during aerobic composting, which changes material flowability and can limit the use of a single set of discrete element method (DEM) parameters. To address this issue for a multi-component corn straw–pig manure mixture, we developed a rapid calibration workflow covering a moisture content range of 29–80%. Angle of repose (AoR) images were obtained using a cylinder-lifting test. To improve robustness for irregular pile contours, we proposed an AoR extraction method that combines LOESS smoothing with least-squares line fitting. Key DEM contact parameters affecting AoR were screened using a Plackett–Burman design, and their effective ranges were refined using a steepest-ascent test. A Box–Behnken design was then used to establish a response surface linking AoR to the significant DEM parameters. In addition, a polynomial relationship between moisture content and AoR was fitted and coupled with the AoR-parameter response surface to predict key DEM parameters directly from moisture content. Validation results showed that the predicted AoR exhibited a relative error below 10% across the tested moisture contents. An independent baffle-lifting validation test yielded a relative error below 5%. Overall, this workflow provided a practical strategy for setting DEM simulations of composting feedstocks under variable moisture content and supports numerical analysis and structural optimization of composting-related machinery. Full article