Search Results (1,110)

To investigate the effects of repeated drying and wetting on the mechanical properties and meso-fabric of metal tailings, lead-zinc tailings from Hunan Province were studied. A self-developed apparatus was used to simulate the cyclic drying-wetting processes. Combined with triaxial shear tests and stereomicroscopic image analysis, the changes in macroscopic mechanical properties and meso-fabric, as well as their correlation mechanisms, were investigated. The results indicate that the wet-dry cycles did not alter the strain-softening characteristics of the tailings’ stress-strain curves; however, they significantly intensified the degree of softening during the later stages of cycling (4–6 cycles). The static strength exhibited a trend characterized by “initial gradual degradation → temporary recovery → further deterioration” with an increasing number of cycles. After six cycles, the strength was significantly reduced compared to the initial state. The effective cohesion (c′) fluctuated markedly, with an amplitude of 31.1%, while the variation in the effective internal friction angle (φ′) was only 6.02%, indicating that dry-wet cycles have a more pronounced effect on the cohesion of tailings. At the microscopic level, the dry-wet cycling process promoted the upward migration of fine particles ranging from 0 to 60 µm, resulting in a decrease in the proportion of smaller particles in the lower layer. The porosity increased overall, with the lower layer rising from 44.06% to 54.26%. Pore evolution was dominated by the enlargement of pores larger than 150 µm. The macro-meso correlation analysis revealed that “fine particle migration → expansion of pores → loss of cementitious material” was the core driving factor for the deterioration of macroscopic mechanics, and the macroscopic mechanical response was the external manifestation of the adjustment of the microscopic structure. This research can provide certain theoretical support for the long-term safe operation and stability improvement of tailings dams. Full article

Declining recovery factors from mature oil fields, coupled with the technical challenges of recovering residual oil under harsh reservoir conditions, necessitate the development of advanced enhanced oil recovery (EOR) techniques. While promising, chemical EOR often faces economic and technical hurdles in high-salinity, high-temperature environments where conventional polymers like hydrolyzed polyacrylamide (HPAM) degrade and fail. This study presents a comprehensive numerical investigation that addresses this critical industry challenge by applying a rigorously calibrated simulation framework to evaluate a novel hybrid EOR process that synergistically combines an ionic liquid (IL) with HPAM polymer. Utilizing core-flooding data from a prior study that employed the same Berea sandstone core plug and Saudi medium crude oil, supplemented by independently measured interfacial tension and contact angle data for the same chemical system, we built a core-scale model that was history-matched with RMSE < 2% OOIP. The calibrated polymer transport parameters—including a low adsorption capacity (~0.012 kg/kg-rock) and a high viscosity multiplier (4.5–5.0 at the injected concentration)—confirm favorable polymer propagation and effective in -situ mobility control. Using this validated model, we performed a systematic optimization of key process parameters, including IL slug size, HPAM concentration, salinity, temperature, and injection rate. Simulation results identify an optimal design: a 0.4 pore volume (PV) slug of IL (Ammoeng 102) reduces interfacial tension and shifts wettability toward water-wet, effectively mobilizing residual oil. This is followed by a tailored HPAM buffer in diluted formation brine (20% salinity, 500 ppm), which enhances recovery by up to 15% of the original oil in place (OOIP) over IL flooding alone by improving mobility control and enabling in-depth sweep. This excellent history match confirms the dual-displacement mechanism: microscopic oil mobilization by the IL, followed by macroscopic conformance improvement via HPAM-induced flow diversion. This integrated simulation-based approach not only validates the technical viability of the hybrid IL–HPAM flood but also delivers a predictive, field-scale-ready framework for heterogeneous reservoir systems. The work provides a robust strategy to unlock residual oil in such challenging reservoirs. Full article

The flotation efficiency of magnesite in the slurry system is critically influenced by its surface wettability. In this work, molecular dynamics (MD) and density functional theory (DFT) calculations were employed to investigate the interactions between water molecules and the magnesite (104) surface. To elucidate the underlying mechanisms, systematic evaluations were conducted, encompassing frontier orbital energies, water molecule adsorption behavior, and the water wetting process. Results indicate that electrons readily transfer from the highest occupied molecular orbital (HOMO) of water to the lowest unoccupied molecular orbital (LUMO) of magnesite. Specifically, the chemisorption of a single water molecule onto the magnesite surface was observed, with a calculated adsorption energy of −91.6 kJ/mol. This process involves an interaction between the oxygen atom of water and a surface magnesium atom, leading to the formation of an Mg–O_W bond. This bond primarily arises from hybridization between the Mg 2p, Mg 2s, and O_W 2p orbitals. Furthermore, water molecules within the first adsorbed monolayer exhibited an average adsorption energy of −66.3 kJ/mol, which further confirms the occurrence of chemisorption. Notably, minimal changes were observed in the orbital interactions between water molecules and surface Mg atoms, a trend consistent with the single-molecule adsorption case. The average adsorption energies for the second and third water layers were calculated to be −63.2 kJ/mol and −45.6 kJ/mol, respectively. The stabilization of the hydration layer structure is attributed to the hydrogen-bonding network formed among water molecules in the outer layers. As the number of water layers increases, the structural disorder of water molecules on the magnesite surface progressively intensifies. This decrease in adsorption energy with increasing layer number is attributed to the progressively enhanced contribution of hydrogen-bonding interactions between water molecules across different layers. Consequently, the magnesite surface exhibits a low contact angle, indicating high intrinsic hydrophilicity. Collectively, these findings provide molecular-level insights into the wettability of the magnesite surface, thereby contributing to a more fundamental understanding of magnesite flotation mechanisms. Full article

The wettability of a carbon fiber surface is an important factor that determines the strength of its bonding with matrices, and hence, an optimized criterion is required to accurately measure the wettability. In this study, the Washburn capillary rise method was used to select the capillary constant with the minimal deviation among various carbon fiber lengths, and it was applied to determine the contact angle and surface free energy of each carbon fiber length according to the wetting liquid. The smallest deviation in the contact angle was observed for a carbon fiber length of 2 inches, and this observation was attributed to the pores in the fibers and the orientation of the carbon fibers packed inside the column. By reducing the number of pores and achieving favorable packing, the surface free energy of carbon fibers can be measured with a high degree of accuracy, contributing to an improved understanding of fiber–matrix interactions. Full article

Background/Objectives: Enhancing excipient functionality through environmentally friendly and scalable processing methods is essential for improving the manufacturability and performance of orally disintegrating tablets (ODTs). Microwave-assisted wet granulation enables controlled microstructural modification without chemical alteration of excipient components. This study aimed to develop and evaluate a rice starch (RS)–mannitol co-processed excipient using microwave-assisted wet granulation for direct compression of ODTs. Methods: RS and mannitol were co-processed by wet granulation followed by microwave treatment under varying power levels and irradiation times. The effects of processing conditions on granule morphology, solid-state properties, porosity, powder flow, compressibility, wettability, and disintegration behavior were systematically investigated. The optimized excipient was further evaluated in ODT formulations containing chlorpheniramine maleate and piroxicam and benchmarked against a commercial co-processed excipient (Starlac^®). Results: Microwave treatment generated internal vapor pressure that promoted pore formation and particle agglomeration, resulting in enhanced powder flowability (compressibility index 8.4–10.8%). Partial crystallinity reduction and microstructural modification improved compressibility and surface wettability compared with non-microwave-treated materials. The optimized formulation (MW-RM-H-30) exhibited rapid wetting (25 s), high water absorption (90.5%), low contact angle (42°), and fast tablet disintegration (31 s). ODTs prepared with MW-RM-H-30 showed rapid disintegration (42 s for chlorpheniramine maleate and 32 s for piroxicam) and dissolution behavior comparable to Starlac^®. Conclusions: Microwave-assisted wet granulation provides an efficient, scalable, and environmentally friendly strategy for engineering starch-based co-processed excipients with enhanced functionality for direct compression ODT applications. The developed excipient demonstrates strong potential for solid dosage form manufacturing. Full article

Methane emissions from rice paddies account for over 11% of global atmospheric CH₄, making water management practices such as Alternate Wetting and Drying (AWD) critical for climate change mitigation. Remote sensing offers an objective approach to monitoring AWD implementation and improving greenhouse gas estimation accuracy. This study investigates the backscattering mechanisms of L-band SAR for inundation/non-inundation classification in paddy fields using full-polarimetric ALOS-2 PALSAR-2 data. Field surveys and satellite observations were conducted in Ryugasaki (Ibaraki) and Sekikawa (Niigata), Japan, collecting 1360 ground samples during the 2024 growing season. Freeman–Durden decomposition was applied, and relationships with plant height and water level were analyzed. The results indicate that plant height strongly influences backscatter, with backscattering contributions from the surface decreasing beyond 70 cm, reducing classification accuracy. Random forest models can classify inundated and non-inundated fields with up to 88% accuracy when plant height is below 70 cm. However, when using this method, it is necessary to know the plant height. Volume scattering proved robust to incidence angle and observation direction, suggesting its potential for phenological monitoring. These findings highlight the effectiveness of L-band SAR for water management monitoring and the need for integrating crop height estimation and regional adaptation to enhance classification performance. Full article

This paper presents a unified aerodynamic design and optimization framework for morphing Blended-Wing-Body (BWB) Unmanned Aerial Vehicles (UAVs) operating in subsonic and near-transonic regimes. The proposed framework integrates parametric CAD modeling, Computational Fluid Dynamics (CFD), and surrogate-based optimization using Response Surface Methodology (RSM) to establish a generalized approach for geometry-driven aerodynamic design under multi-Mach conditions. The study integrates classical aerodynamic principles with modern surrogate-based optimization to show that adaptive morphing geometries can maintain efficiency across varied flight conditions, establishing a scalable and physically grounded framework that advances real-time, high-performance aerodynamic adaptation for next-generation BWB UAVs. The methodology formulates the optimization problem as drag minimization under constant lift and wetted-area constraints, enabling systematic sensitivity analysis of key geometric parameters, including sweep, taper, and twist across varying flow regimes. Theoretical trends are established, showing that geometric twist and taper dominate lift variations at low Mach numbers, whereas sweep angle becomes increasingly significant as compressibility effects intensify. To validate the framework, a representative BWB UAV was optimized at Mach 0.2, 0.4, and 0.8 using a parametric ANSYS Workbench environment. Results demonstrated up to a 56% improvement in lift-to-drag ratio relative to an equivalent conventional UAV and confirmed the theoretical predictions regarding the Mach-dependent aerodynamic sensitivities. The framework provides a reusable foundation for conceptual design and optimization of morphing aircraft, offering practical guidelines for multi-regime performance enhancement and early-stage design integration. Full article

The stability of bank slopes in pumped storage power stations is crucial, particularly in regions where frequent water level fluctuations occur. This study aims to investigate the degradation mechanism of bank slope under such fluctuating conditions, focusing on granite residual soil from the pumped storage power stations in Fujian, China. To explore the effects of drying-wetting cycles and matric suction on soil shear strength, drying and wetting cycles were conducted with unsaturated triaxial shear tests. The results revealed that the shear parameter strengthening effect occurs when the matric suction increases from 50 kPa to 200 kPa. Moreover, during the first five drying-wetting cycles, soil shear strength decreased sharply, with cohesion and internal friction angle decreasing by approximately 15.4% and 11.2%, respectively. This degradation trend stabilized in the later cycles. Scanning Electron Microscopy (SEM) analysis of the soil microstructure showed an evolution from a dense structure to a penetrating cavity during the cycles. This change reflects that the strength degradation characteristics of granite residual soils are controlled by the synergistic effects of structural and frictional mechanisms, manifesting as initial degradation followed by stabilization. Additionally, by fitting the nonlinear characteristics of the experimental data, shear strength evolution functions for matric suction and drying-wetting cycles were established, revealing the effect of these factors on strength degradation. These findings provide a theoretical basis for the stability analysis of bank slopes in pumped storage power stations, offering insights into soil behavior under fluctuating water levels. Full article

Driven by environmental concerns, the packaging industry is shifting toward high-performance and bio-based coating alternatives. In this research, poly(methylmethacrylate) (PMMA) and modified cellulose nanocrystal (m-CNC) were employed as reinforcing agents to develop sustainable poly (lactic acid)-based coatings for packaging applications. Various formulations, influenced by polymer matrix blends and m-CNC loadings (1–5%), were prepared using solvent and applied as protective coating on cardboard paper substrates. The grammage of polymeric coatings (CG) on paper was also investigated using various wet film thicknesses (i.e., 150–250 μm). Accordingly, key parameters including water contact angle, thermal behavior, mechanical performances and barrier properties were systematically evaluated to assess the effectiveness of the developed nanocomposite coatings. As a result, nonylphenol ethoxylate surfactant-modified cellulose nanocrystals exhibited good dispersion and stable suspension in chloroform for one hour, improving compatibility and interaction of polymer–CNC fillers. The water vapor permeability (WVP) of PLA-coated papers was significantly reduced by blending PMMA and increasing the content of m-CNC nanofillers. Furthermore, CNC incorporation enhanced the oil resistance of PLA/PMMA-coated cardboard. Pronounced improvements in barrier properties were observed for paper substrates coated with dry coat weight or CG of ~20 g/m² (corresponding to 250 μm wet film thickness). Coatings based on blended polymer—particularly those reinforced with nanofillers—markedly enhanced the hydrophobicity of the cardboard papers. SEM-microscopy confirmed the structural integrity and morphology of the nanocomposite coatings. Regarding mechanical properties, the upgraded nanocomposite copolymer (PLA-75%/PMMA-25%/m-CNC3%) exhibited the highest bending test and tensile strength, achieved on coated papers and free-standing polymeric films, respectively. Based on DSC analysis, the thermal characteristics of the PLA matrix were influenced to some extent by the presence of PMMA and m-CNC. Overall, PLA/PMMA blends with an optimal amount of CNC nanofillers offer promising sustainable coatings for the packaging applications. Full article

Bacterial biosurfactants have potential applications in green cleaning due to their environmental friendliness. Among all isolated bacterial strains in this study, strain N33 exhibited the most potent oil-displacing activity and was identified as Pseudomonas aeruginosa. Its biosurfactant yield was approximately 550 mg/L, and structural characterization revealed it to be a glycolipid-type biosurfactant. The oil-displacing ring diameters of the biosurfactant against vegetable oil, paraffin oil, and crude oil reached 6.3 ± 0.3 cm, 5.8 ± 0.2 cm, and 3.8 ± 0.5 cm, respectively. Its critical micelle concentration (CMC) was determined to be 150 mg/L, with a corresponding surface tension of 39.55 mN/m. Notably, this bacterial biosurfactant significantly improved interfacial wettability, reducing the contact angles of vegetable oil, paraffin oil, and crude oil on oil-wetted glass slides from 93.0°, 99.0°, and 98.8° to 10.0°, 15.0°, and 19.0°, respectively. The emulsification efficiency for the three oils was 80%, 57%, and 10%, respectively. Furthermore, capillary oil removal assays verified that the biosurfactant could efficiently strip oil films from the inner walls of capillaries. These findings demonstrate that the biosurfactant produced by P. aeruginosa strain N33 possesses considerable oil-removal efficacy, thereby providing a novel candidate for the research, development, and application of green detergents. Full article

In this study, cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT) are employed to systematically investigate surface and wetting properties on hydrophobic surfaces, specifically in mixed solvents composed of ethylene glycol (EG) and water at 298.15 K. By varying the concentration of each surfactant within the EG–water mixture, both surface tension and contact angle measurements are performed to elucidate how surfactant type and solvent composition influence interfacial behavior and wettability. PTFE and wax surfaces were chosen as model hydrophobic surfaces. Surface tension measurements obtained in pure water and in water–EG mixtures containing 5, 10, and 20 volume percentage EG reveal a consistent decrease in the premicellar slope (${\displaystyle \frac{d\gamma }{d\mathit{log}C}}$) with increasing EG content. This reduction reflects weakened hydrophobic interactions and less effective surfactant adsorption at the air–solution interface. The corresponding decline in maximum surface excess (${\Gamma }_{max}$) and increase in minimum area per molecule ($A_{min}$) confirm looser interfacial packing due to EG participation in the solvation layer. Plots of adhesion tension (A_T) versus surface tension (γ) exhibit negative slopes, consistent with reduced solid–liquid interfacial tension (${\Gamma }_{LG}$) and greater redistribution of surfactant molecules toward the solid–liquid interface. AOT shows stronger sensitivity to EG compared to CTAB, reflecting structural headgroup-specific adsorption behavior. Work of adhesion (W_A) measurements demonstrate enhanced wettability at higher EG concentrations, highlighting the cooperative impact of co-solvent environment and surfactant type on wetting phenomena. Full article

Horizontal wells combined with multi-stage fracturing are key techniques for extracting tight oil formation. However, due to the ultra-low permeability and porosity of reservoirs, energy depletion occurs rapidly, necessitating external supplements to sustain production. During the hydraulic fracturing process, large volumes of fracturing fluid are injected into reservoirs, increasing its pressure to a certain extent. However, due to the oil-wet nature of the formation, the fracturing fluid cannot penetrate the rock, failing to enhance oil recovery during the shut-in period. Surfactant-based nanofluids have been introduced as fracturing fluid additives to reverse rock wettability, thereby boosting imbibition-driven recovery. Although the imbibition has been studied to inspire the tight oil recovery, few studies have demonstrated the imbibition in enhanced fossil hydrogen energy, which further promotes the imbibition recovery. In this paper, complex nanofluid dispersions (CND) have been proved to enhance the tight reservoir pressure. Through contact angle and imbibition experiments, it is shown that CND can transform oil-wet rock to water-wet, reduce the adhesion of oil, and improve the ultimate oil recovery through the imbibition effect. Then, core flow testing experiments were conducted to show CND can decrease the flow resistance and improve the swept area of the injected fluid. In the end, pressure transmission tests were conducted to show CND can enhance the formation energy and production after fracturing. Results demonstrate that CND enables the fracturing fluid to travel further away from the hydraulic fractures, thus decreasing the depletion of tight formation pressure and maintaining a higher oil production rate. Results help optimize the design of the hydraulic fracturing of tight offshore reservoirs. Full article

To investigate the variation in shear strength of expansive soil under dry–wet cycles, laboratory direct shear tests were conducted on remolded soil from a foundation pit in the Chengdu area. The tests were performed under controlled drying and wetting paths, with systematic variations in water content (w), number of dry–wet cycles (N), and dry density (ρ). The characteristics and evolution of shear strength under these conditions were analyzed. Using a nonlinear multiple surface fitting method, empirical relationships were established between the soil’s shear strength parameters (cohesion c and internal friction angle φ) and the variables w and N. Furthermore, equations describing the attenuation of these parameters with respect to ρ and N were derived. Based on the experimental data and within the framework of the Mohr–Coulomb strength theory, a practical predictive model was developed for the shear strength of expansive soil under the coupled effects of dry–wet cycles, water content, and dry density. Verification results demonstrate that the model predictions are in good agreement with experimental measurements. The proposed model provides a practical reference for estimating the shear strength of similar expansive soils in the Chengdu area under cyclic drying and wetting conditions. Full article

We present a theoretical and numerical framework for computing asymmetric two-dimensional droplet shapes on surfaces with a sharp wetting boundary separating regions of distinct contact angles. Through Lagrange multiplier analysis of the constrained Gibbs free energy functional, we derive a simplified spreading condition that relates the contact line position ratio to the ratio of spreading functions encoding unbalanced Young stress at each contact line, reducing to an explicit algebraic relation that eliminates iterative computation. Gravitational effects substantially modify droplet height and curvature distribution across Bond number regimes, yet the contact line position ratio remains invariant, confirming that horizontal partitioning depends exclusively on interfacial energy ratios rather than body forces. Hydrophilic surfaces exhibit intuitive spreading toward regions with better wettability, producing flattened asymmetric profiles, while hydrophobic surfaces display counterintuitive behavior where droplets preferentially occupy regions with poorer wettability, maintaining tall compact geometries. Mixed hydrophilic–hydrophobic boundaries violate equilibrium conditions and drive spontaneous droplet migration. We develop an efficient two-stage computational strategy decoupling shape computation from equilibrium position determination, reducing computational cost by orders of magnitude. These findings provide quantitative design criteria for controlled droplet positioning on patterned substrates, with implications for microfluidic devices and droplet-based technologies. Full article

The titanium alloy Ti-6Al-4V is widely used in the aerospace, medical, and automotive industries; however, its machining remains challenging due to its low thermal conductivity and high chemical reactivity. This study investigates the influence of the tool clearance angle on tool wear during the turning of Ti-6Al-4V under wet cutting conditions. A Design of Experiments (DoE) approach was employed, varying the clearance angle, cutting speed, and feed rate to determine their effects on tool wear. Tool wear was analysed using 3D topography measurements. Regression analysis was used to evaluate the experimental data with the main objective of quantifying the impact of the individual factors and their interactions, resulting in the development of a predictive statistical model. The model’s accuracy was assessed using the coefficient of determination (R²) and the adjusted coefficient of determination (R²adj). The results demonstrate that the clearance angle has a significant impact on crater wear formation and overall tool life. An optimised moderate clearance angle reduces tool degradation, enhances tool life, and improves the surface integrity of the machined component. Full article