Search Results (1,806)

This work characterizes oil film evolution and predicts the hydrostatic-to-hydrodynamic dominance transition in low-speed heavy-duty journal bearings under starved lubrication induced by insufficient inlet pressure, accounting for the thermo-viscous coupling effect. A thermo-viscous coupling model (TVCM) based on the Vogel equation is established and compared with the conventional constant viscosity model (CVM). Analyses are conducted with VG460, VG680, and VG1000 lubricants at rotational speeds of 10–50 rpm. Results show that the CVM systematically overestimates temperature rise and effective viscosity by neglecting the negative feedback among temperature rise, viscosity attenuation, and reduced heat generation, with deviations increasing with rotational speed and lubricant viscosity. Under insufficient oil supply, load-carrying capacity rises rapidly then stabilizes, reflecting the hydrostatic-to-hydrodynamic dominance transition. In the hydrodynamic-dominated stage, a dominance shift between hydrodynamic enhancement and thermal softening is identified: the peak load point marks the switching of dominant factors, and the corresponding critical speed decreases with rising lubricant viscosity. This transition is accompanied by a failure mode shift from global oil film breakdown to localized high-temperature adhesive wear and fatigue spalling. These findings provide a theoretical basis for formulating emergency speed limits and safe operation strategies for journal bearings under insufficient oil supply. Full article

Rolling bearings serve as core rotating components in high-end equipment such as aerospace systems, wind turbines, and high-speed electric multiple units, and their service life directly affects the operational reliability and service life of the host machinery. To clarify the research landscape of rolling bearing life prediction, summarize existing prediction techniques, and identify future development trends, this paper systematically reviews the major research advances in this field. The review first traces the evolution of bearing life models, with particular emphasis on the roles of key influencing factors, including stress thresholds, material defects, and lubrication conditions, in their development. Second, it presents a comparative analysis between conventional life calculation methods and those that account for dynamic variations in lubrication conditions, thereby revealing the influence patterns and underlying mechanisms through which surface topography and oil-film characteristics affect fatigue life. Third, it discusses methods for assessing bearing system life, with special attention given to accelerated life testing techniques and bearing condition monitoring approaches. Finally, it summarizes the state of the art in data-driven bearing life prediction and identifies online sensing of lubrication states, system-level reliability design, and improvements in the interpretability and robustness of AI-based prediction models as important future research directions in rolling bearing life prediction. Full article

With the continuous increase in horizontal displacement during unconventional oil and gas drilling, drilling operations are commonly plagued by high frictional resistance, severe pipe sticking issues and difficulties in directional drilling. Conventional single-component water-based drilling fluid lubricants fail to satisfy multifunctional demands, including high-temperature resistance, salt tolerance and long-term lubrication. In this work, a novel microsphere lubricant, RB-Si, with high-temperature and high-salinity resistance was developed by combining the merits of solid and liquid lubricants. The product was synthesized using myristic acid and triethanolamine as raw materials via co-reaction with boric acid and nano-silica. Laboratory tests reveal that after aging at 180 °C, the lubrication coefficient reduction rates of based mud, saturated salinity-based mud and a high-density (2.0 g/cm³) drilling fluid gel system containing 1.0 wt% RB-Si reached 90.1%, 83.3% and 62.8%, respectively. Meanwhile, RB-Si can effectively plug the micropores in the filter cake, reduce fluid loss, inhibit shale hydration and swelling, and exhibit excellent compatibility with drilling fluids. RB-Si rapidly adsorbs onto the surfaces of metallic drill strings and formation rocks to construct a durable and high-strength lubricating film, accompanied by the rolling friction of the incorporated microspheres, thereby reducing frictional drag between the drill string/casing and the drill string/borehole wall. This lubricant effectively mitigates high frictional resistance under prolonged friction conditions, and is expected to provide technical support for long-horizontal-well drilling. Full article

In axial piston pumps under variable loading, the system-level excitation and local tribological responses of the slipper pair can become temporally and spatially decoupled. The scientific contribution of this paper is a phase-consistent chain that achieves three things: it resolves the central-pocket pressure boundary with a dual-orifice and dual-control-volume model instead of directly imposing piston chamber pressure, propagates this boundary through posture-dependent clearance to three-dimensional flow–thermal and single-slipper structural responses within the same local cycle, and screens candidate high-risk regions from the spatial proximity and phase relationship of multi-field cycle envelopes rather than from a single peak. The results show that the central pocket pressure exhibits peak attenuation, peak-time difference, and pressure-rate weakening relative to the piston chamber pressure. The steady peak attenuation ratio is $2.83$–$3.33\%$, while pressure-rate weakening under variable loading is $6.29$–$7.14\%$; the high-to-low unloading case gives the largest attenuation of $4.81\%$. Increasing steady load reduces the tilt amplitude and raises the minimum film thickness from about $13.024$ to $13.452\mathsf{\mu }\mathrm{m}$, but the maximum temperature rise increases from $34.12$ to $65.01\mathrm{K}$. A $10\%$ cycle-envelope projection shows no common overlap among the film-thinning, oil-film temperature-rise, and structural-stress core high-response regions with pairwise overlap ratios of 0–$3.27\%$. This traceable chain supports comparative lubrication-safety screening; the identified zones remain numerical candidates rather than experimentally confirmed wear or failure regions. Full article

Open-surface coalescence of microdroplets is essential for droplet-based microreactors, emulsion processing, and multiphase microfluidics, yet existing methods often require closed channels or patterned electrodes. Here, we report a corona-driven open-oil-film platform that achieves voltage-regulated coalescence of aqueous microdroplets in a simple needle–plate electrode configuration. Positive corona discharge induces coupled electrohydrodynamic effects—including ion transport, interfacial charge redistribution, and Maxwell stresses—that drive oil-film contraction and charge-regulated droplet bouncing, thereby reducing inter-droplet spacing and promoting successive merging. The coalescence rate and final droplet size are tunable via the applied voltage and oil volume: complete coalescence into a single droplet is achieved at 12 kV, and an optimal oil volume of 60 μL maximizes confinement efficiency. To enable quantitative, frame-by-frame analysis, we develop an improved YOLOv5–OC-SORT framework that yields an overall mAP@0.5 of 0.905 for automatic droplet detection and tracking. As a proof-of-concept, the platform achieves electro-demulsification of a surfactant-stabilized water-in-oil emulsion, increasing the average droplet diameter from ~0.005 mm to ~0.2 mm and enabling effective oil–water separation. This work provides a simple, electrode-pattern-free strategy for controllable droplet coalescence and open-surface emulsion breaking. Full article

Chronic wounds remain a significant clinical challenge due to persistent inflammation and impaired tissue repair. Anti-inflammatory agents play a pivotal role in wound management by reducing excessive inflammation, preventing further tissue damage, and creating a microenvironment conducive to healing. Among them, Ketoprofen, a non-steroidal anti-inflammatory drug, is effective in modulating inflammation. However, its systemic administration is associated with adverse effects, highlighting the need for localized and controlled delivery systems. Gelatin-based carriers provide important advantages, including biocompatibility, biodegradability, low immunogenicity, cost-effectiveness, and the ease of chemical modification to tailor drug release profiles. In this pioneering study, gelatin-based microspheres crosslinked with tannic acid were developed to achieve sustained topical release of Ketoprofen. The microparticle system was produced through the single water-in-oil emulsification process and optimized by varying homogenization speed, crosslinking time, and molar ratio. Morphological, physicochemical, functional, and biological characterizations were conducted. The optimized formulation yielded spherical microspheres (5–35 µm) with high crosslinking efficiency and a controlled drug release profile over time. COX inhibition assays provided preliminary evidence that released Ketoprofen-retained inhibitory activity under the assay conditions, while cytocompatibility tests supported the short-term compatibility of the system within the tested concentration range. A qualitative wound-model test provided preliminary evidence of powder hydration, film formation, and macroscopic retention. Overall, tannic acid-crosslinked gelatin microspheres represent a biocompatible and promising platform for localized drug delivery of non-steroidal anti-inflammatory in wound management. Full article

The demand for sustainable food preservation has driven the development of biodegradable alternatives to conventional, petroleum-based plastics. This study developed and evaluated bioactive starch-based films incorporated with citrus peel essential oils (lemon, orange, and tangerine) at concentrations ranging from 0.5% to 2% (w/w). The physical, chemical, mechanical, and antimicrobial properties of all film formulations containing 0.5–2% (w/w) essential oils were evaluated. Based on the experimental design, only the selected formulations containing 1 and 2% essential oils were subjected to structural and thermal characterization (XRD, SEM, FTIR, and TGA/DTG), transparency measurements, soil biodegradation, and phytotoxicity assays. FTIR spectroscopy revealed that oil incorporation did not alter the characteristic chemical bands of starch, indicating predominantly physical interactions. The essential oils modulated the physical and mechanical performance of the films. The films containing lemon and tangerine essential oils exhibited superior antimicrobial activity against foodborne pathogens. Furthermore, soil biodegradation was concentration-dependent, with mass loss exceeding 50% within 15 days, while phytotoxicity tests confirmed the environmental safety of the degraded residues. These findings demonstrate that the developed citrus-infused starch films hold great promise as active biodegradable packaging to extend the shelf life of bakery products and mitigate plastic waste. Full article

Systematic field data on adjuvant-amended microbial-derived pesticides against L. pratensis in arid, high-ultraviolet cotton regions remain scarce. This study systematically evaluated the laboratory toxicity and field efficacy of four kinds of microbial-derived pesticides (abamectin, emamectin benzoate, B. bassiana, and M. anisopliae) and their combinations with adjuvants against L. pratensis in Xinjiang cotton fields. As a comprehensive regional study, this work elucidates the differential enhancement patterns of d-limonene and mineral oil on antibiotic insecticides and entomopathogenic fungi, providing targeted field data for pesticide reduction strategies. The laboratory toxicity of seven microbial-derived pesticides was determined using the leaf-tube residual film method. Four effective agents were selected and combined with d-limonene or mineral oil for field efficacy trials. Abamectin and emamectin benzoate exhibited rapid and high insecticidal activity, with 48 h LC₅₀ values of 1.198 mg/L and 3.424 mg/L, respectively. The two entomopathogenic fungi exhibited slower insecticidal activity than the chemical insecticides but maintained relatively stable control effects throughout the observation period. In field trials, when abamectin or emamectin benzoate was applied at a 30% reduced rate in combination with mineral oil or d-limonene, the control efficacy was equivalent to or higher than that of the full-rate application of the pesticide alone. The treatment of abamectin (4.20 g a.i./hm²) plus mineral oil achieved the highest control efficacy (89.24%) at 3 days post-treatment. For B. bassiana and M. anisopliae, reduced-rate adjuvant-amended treatments showed numerically higher initial and residual efficacy than the full-rate single-agent fungal treatments. The treatment of M. anisopliae (7.35 × 10¹² spores/hm²) plus d-limonene reached 70.50% efficacy at 7 days post-treatment, which was significantly higher than that of the full-rate fungal treatment alone. No phytotoxicity symptoms were observed on cotton plants. Under the tested conditions, the rational combination of microbial-derived pesticides with appropriate adjuvants demonstrates the potential for a 30% reduction in pesticide dosage while maintaining or improving field efficacy, providing region-specific reference for the sustainable management of L. pratensis in Xinjiang cotton fields. Full article

Potato starch extrudates, chemically modified by a K₂CO₃ catalyst and enriched with two types of edible oils (rapeseed or sunflower) at varying concentrations (3%, 6%, 9%), were used as film substrates. This study was carried out as a continuation of previous research on analogous extrudates in the form of dry powders and liquid solutions. The main objective was to determine surface properties of polysaccharide films as a function of oil type and concentration to monitor their wettability, biocompatibility, and functional characteristics (e.g., transparency, colour, thickness, flexibility, solubility). Advancing and receding contact angles for polar liquids (water and formamide) and non-polar diiodomethane were measured on the base and oil-modified extruded starch films. Based on these measurements, the surface free energy of the films was determined using the contact angle hysteresis (CAH) model. Optical profilometry confirmed the wettability results through surface morphology and roughness evaluation. Additionally, FTIR analysis of the films was compared to the FTIR spectra of extruded starch powders. Combining these methods provided an in-depth characterization of the films, thereby improving control over their stability and wettability, which is essential for applications in the pharmaceutical and food industries to extend product freshness and enhance resistance to oxidation and spoilage. Full article

When predicting cavitation erosion risk in practical engineering bearings, traditional vapor cavitation models neglect the effect of dissolved air in the lubricant and fail to account for its precipitation and dynamic evolution in local low-pressure regions, leading to deviations in the prediction of cavitation extent, intensity, and distribution. Taking the main bearing of a certain type of diesel engine as the research object, a coupled cavitation model combining the Schnerr–Sauer vapor cavitation model and a Henry’s law-based gas dissolution model is established. Together with large eddy simulation (LES), the accuracy of the numerical model is verified by constructing a visualization experimental platform. Numerical analysis is then carried out to investigate the effect of dissolved air in the lubricant on the cavitating flow field of the bearing oil film under initial conditions ranging from undersaturated to saturated states (air mass concentration of 0–0.4 g/L). The results show that as the mass concentration increases, the amount of air precipitation in the near-wall region gradually increases and extends downstream. When the mass concentration reaches 0.1 g/L, the precipitated air mass reaches 50% of the vapor cavitation mass, significantly expanding the cavitation range. In the critical mass concentration range of 0.24–0.28 g/L, intense air precipitation occurs inside the oil hole and covers the entire region. Through the synergistic effects of inhibiting high-speed jets, altering the local pressure field, and competing for cavitation nuclei, the precipitated air significantly suppresses the development of near-wall vapor cavitation, and the vapor cavitation mass decreases by 83.1% at saturation. In summary, within the practical mass concentration range, the presence of dissolved air significantly enhances the gas phase intensity near the bearing bush surface and expands the cavitation range, thereby exacerbating the risk of cavitation erosion damage in this region, while having little effect on the oil supply performance of the oil hole. Full article

Water-based enhanced oil recovery (EOR) techniques continue to attract interest because of their technical practicality and economic feasibility. Hybrid low-salinity surfactant flooding is a promising EOR strategy for carbonate reservoirs; however, the coupled effects of low-salinity brine, surfactant addition, wettability alteration, electrostatic modification, and capillary pressure reduction remain difficult to isolate. This study investigates hybrid low-salinity surfactant flooding in restored tight carbonate cores using integrated experimental measurements and core-scale numerical modeling. The experimental workflow included oil–water interfacial tension (IFT), zeta potential, contact angle measurements using a custom-designed HPHT imbibition cell, and reservoir-condition HPHT coreflooding under sequential and standalone injection schemes. The sequential flood evaluated the transition from seawater (SW) to 1%diluted seawater (1%dSW) and then to 1%dSW+A-1 surfactant, while standalone floods assessed the direct displacement performance of 1%dSW and 1%dSW+A-1. Dilution from SW to 1%dSW increased IFT from approximately 10.2 to 14.9 mN/m, indicating that the recovery improvement during 1%dSW injection was not caused by IFT reduction. Instead, zeta potential and contact angle results indicated progressive electrostatic modification and wettability alteration toward a less oil-wet state. The contact angle decreased from approximately 123° for SW to 101° for 1%dSW and further to 84° after A-1 addition. In contrast, 1%dSW+A-1 reduced IFT sharply to approximately 0.178 mN/m at 0.2 wt%, lowering the estimated capillary pressure magnitude and weakening capillary trapping. Sequential coreflooding showed that SW recovered 42.65% OOIP, followed by an additional 24.21% OOIP from 1%dSW and 9.11% OOIP from 1%dSW+A-1. Standalone 1%dSW and 1%dSW+A-1 recovered approximately 58.44% and 65.82% OOIP, respectively. Core-scale models reproduced the main recovery and pressure drop trends using zeta potential-guided relative permeability and capillary pressure functions supported by surface complexation modeling concepts. Overall, 1%dSW+A-1 improved oil displacement through a synergistic mechanism in which low-salinity brine stabilized the water film and altered wettability, while A-1 surfactant reduced IFT and weakened capillary trapping. The integrated experimental and modeling workflow provides a mechanistic basis for evaluating hybrid low-salinity surfactant flooding and for linking laboratory-measured interfacial properties to effective core-scale rock–fluid functions. Full article

The accessory gearbox of an aero-engine operates under high-speed and heavy-load conditions, where insufficient lubrication may lead to oil-film failure, increased frictional losses, and reduced transmission reliability. Therefore, understanding oil-jet injection and tooth surface oil-film spreading characteristics is essential for improving lubrication performance. In this study, a three-dimensional geometric model incorporating the meshing region and oil nozzles was established based on a typical accessory gear pair. The model employs the VOF multiphase flow approach and the standard k-ε turbulence model, coupled with dynamic mesh techniques to accurately capture the transient interactions between gear rotation and oil–air two-phase flow. Numerical simulations reveal the dynamic evolution of oil injection, impingement on the tooth surface, oil-film spreading, and transport into the meshing zone, while the effects of injection velocity and nozzle length on lubrication performance are quantitatively analyzed. Results indicate that an injection velocity of 45–55 m/s yields optimal oil-film coverage and uniformity, and a nozzle length of h = 30 mm minimizes jet energy decay and airflow interference, achieving uniform oil filling in the meshing zone. The optimal lubrication performance for accessory gears is obtained at an injection velocity of 45–55 m/s and a nozzle length of 30 mm. This study provides a reference for the design optimization of accessory gear lubrication systems. Full article

This study aimed to determine the effects of whey protein isolate (WPI)-based edible gel coatings, enriched with different additives, on the quality parameters of strawberries (Fragaria x ananassa). The coating solutions were prepared in five different formulations: control (uncoated), WPI-based gel coating (GC), WPI + magnesium powder (GCMg), WPI + cinnamon essential oil (GCEo), and WPI + magnesium + cinnamon essential oil (GCMgEo). In the study, each experimental group was stored at 4 °C for 21 days and evaluated in terms of color parameters (L*, a*, b*, C*, h°, ∆E), weight loss, pH, Water soluble dry matter (WSDM), moisture content, redox potential (Eh), adhesion rate of the coating, decay percentage, texture analysis, and sensory properties. The results revealed that the GCMgEo group yielded the most successful outcomes in terms of color stability, oxidative resistance, and microbial control. However, sensory evaluation scores in this group were found to be lower compared to other groups. The highest overall acceptability scores were observed in the control group up to the 14th day. The coating applications were found to preserve the firmness and integrity of the strawberries, while the adhesion percentage increased with certain additives. Moreover, WPI-based coatings formed a protective film on the fruit surface, providing protection against compression and mechanical damage. These results indicate that while edible coatings slow down the ripening process, some additives may have negative effects on aroma and taste. As a result, WPI-based edible gel coatings have the potential to extend the shelf life of strawberries and reduce quality losses. The addition of magnesium and cinnamon essential oil enhances the functional performance of the coatings but requires sensory optimization. This study reveals that naturally derived coating systems can offer an eco-friendly and effective alternative for preserving fresh fruits. Full article

Joint clearances inevitably deteriorate kinematic accuracy and operational stability of heavy-load mechanical presses. Most existing studies focus on single-type clearances or uniform contact states, failing to reveal the coupled dynamic behavior of multi-type clearances with differentiated lubrication conditions. This work develops a five-degree-of-freedom coupled dynamic model for a double-crank mechanical press, integrating hydrodynamic lubricated revolute joints and dry contact–impact translational joints. Nonlinear dynamic responses under varying clearances, driving speeds and contact regimes are systematically analyzed. Results show that moderately enlarged translational clearance improves positioning accuracy by suppressing oil film whirl-induced chaos; lubricated revolute joints effectively isolate high-frequency impact energy via squeeze-film damping, and the system exhibits non-monotonic dynamic characteristics with speed. This study provides a theoretical basis for clearance matching and operating optimization of mechanical presses. Full article

This study explores the valorization of olive pomace through the green recovery of bioactive phenolic compounds for application in active packaging for olive oil preservation, alongside the development of a low-cost analytical strategy aligned with white analytical chemistry principles. Ultrasound-assisted extraction using 50% (v/v) aqueous ethanol significantly improved polyphenol recovery, reducing extraction time to 2 min while increasing efficiency compared to conventional maceration. Total phenolic content was determined using the Folin–Ciocalteu method and measured with both a UV–Vis spectrophotometer and a portable 3D-printed smartphone-based device, which showed excellent agreement with the reference method and comparable analytical performance. Optimized extracts were incorporated into starch–glycerol films, enhancing UV-barrier properties and enabling controlled release of phenolics. When applied to olive oil packaging, the films reduced color degradation under accelerated aging, indicating improved photo-oxidative stability. Composting tests suggested the biodegradation capability of the developed materials under the evaluated conditions. Overall, the study demonstrates an integrated sustainable approach combining waste valorization, active packaging development, and accessible analytical innovation. Full article