Search Results (487)

Studying Bingham flows in permeable media under a periodic magnetic field enhances the understanding of yield-stress fluids for applications like oil recovery and filtration. This study combines non-Newtonian behavior with porous-medium resistance and magnetic variations, facilitating the analysis of complex flow phenomena, including oscillatory yielding and improved flow control in porous structures. The viscous potential theory is employed to streamline the mathematical processes. The utilization of linear governing partial differential equations of motion, along with appropriate nonlinear boundary conditions, yields additional simplifications. The investigation yields a nonlinear Mathieu oscillator that governs the interfacial displacement. A non-perturbative method is used to convert this nonlinear ordinary differential equation into a linear equation. A non-dimensional formulation minimizes the fundamental variables required to characterize the system by establishing a collection of dimensionless physical characteristics. The study analyzes a nonlinear Mathieu oscillator with complex coefficients to explore system dynamics related to elevation. By simplifying the variable coefficients, it enhances the examination of stability and resonance behavior. Despite inherent complexities, the work effectively clarifies fundamental concepts, contributing to a more coherent understanding of the subject. The Hartman number, magnetic field, and magnetic permeability ratio exert a destabilizing effect. Conversely, the Bingham parameter, Weber number, and periodic frequency exert a stabilizing influence. Full article

To overcome the computational bottlenecks of iterative Computational Fluid Dynamics (CFD) in turbomachinery design, this study introduces a real-time, data-driven inverse design framework for 2D uncooled, high-Reynolds turbine blades. The novelty of this work lies in the application of Kolmogorov–Arnold Networks (KAN), a distinct deep-learning architecture, to predict blade geometry and performance metrics from aerodynamic loading inputs. The foundation of the model is a comprehensive database of approximately 30,000 blade profiles, generated through an automated optimization pipeline coupled with the MISES solver. This dataset explores an extensive design space, covering inlet flow angles from $-{50}^{\circ }$ to $0^{\circ }$ and outlet angles from ${50}^{\circ }$ to ${75}^{\circ }$, with flow turning up to ${125}^{\circ }$. A rigorous benchmarking campaign compares KAN against Multi-Layer Perceptrons (MLPs) and Gaussian Process Regression (GPR), highlighting KAN’s capability to overcome the scalability bottlenecks of Gaussian Process Regression to enable real-time performance while achieving MLP-level accuracy with significantly fewer parameters. A further analysis regarding the trade-off between database size and filtration of unfeasible designs indicates that an optimal data filtration threshold exists, balancing noise reduction with model robustness. The final KAN tool achieves real-time inference speeds (∼0.1 s), reducing the design cycle by four orders of magnitude compared to traditional solvers, while maintaining high accuracy (mean outlet angle error of ${0.086}^{\circ }$ and Mach profile RMS error of $0.004$). Furthermore, the model’s predicted RMS error is exploited as a quantitative proxy for aerodynamic feasibility, identifying ill-posed inverse problems where the target loading cannot be physically realized. This metric enables the generation of comprehensive maps that rigorously delineate the boundaries of the viable design space across arbitrary aerodynamic loading styles, providing physics-aware guidelines for preliminary design. Full article

Apical perforation is a possible complication during root canal treatment, often caused by instrumentation beyond the working length, and requires prompt, precise sealing. In immature teeth needing endodontic therapy, the same principles used for managing apical perforations apply. Despite the widespread use of calcium silicate cement (CSC)-based materials, there is limited evidence comparing the sealing performance of putty-type CSCs and injectable bioceramic sealers in apical perforations under standardized laboratory conditions. This study aimed to compare the sealing ability of Retro-MTA cement and Endoseal MTA sealer in standardized apical perforations using the fluid-filtration method. In this in vitro study, 34 extracted human maxillary central incisors were used and divided into two groups. In Group 1, apical perforations were sealed with Retro-MTA and obturated using warm vertical compaction. In Group 2, perforations were sealed with Endoseal MTA and obturated using the single-cone technique. Micro-leakage was assessed using the fluid-filtration method. Data were analyzed with an independent t-test (α = 0.05). All samples exhibited leakage after two weeks. However, Retro-MTA demonstrated significantly lower micro-leakage than Endoseal MTA (0.265 vs. 0.473 μL/min/cmH₂O; p < 0.001), corresponding to approximately a 44% difference in leakage values between the two materials. The findings indicate that Retro-MTA provides a superior apical seal and lower leakage rates than Endoseal MTA. Therefore, Retro-MTA appears to be the more effective material for sealing apical perforations and managing open apices, potentially providing more stable apical seal under controlled laboratory conditions. Full article

Objectives: This study compared the risk profiles, nutrient intake, and kidney function of calcium oxalate stone formers with and without enteric hyperoxaluria. Methods: Thirty-seven patients with calcium oxalate stone disease and enteric hyperoxaluria (cases) and 37 sex- and age-matched idiopathic calcium oxalate stone formers (controls) were enrolled. Patients did not receive any nutritional counseling prior to the start of the study, and they discontinued medications affecting urinary parameters four weeks before their study participation. Anthropometric, clinical, and metabolic parameters were recorded. Dietary and 24-h urinary variables were measured under the habitual diet and under a balanced, standardized diet. The [¹³C₂] oxalate absorption and calcium loading tests were carried out. Results: The median [¹³C₂] oxalate absorption was significantly higher in cases (14.8%) than in controls (8.9%). Under the balanced diet, hypocitraturia, hypomagnesuria, low urine volume and pH value were significantly more common in the case group, whereas hypercalciuria occurred more frequently in the control group, affecting 45.9% of controls and 5.4% of cases. Furthermore, the control group exhibited a greater reduction in urinary calcium excretion under the balanced diet. Urinary oxalate excretion and the ion-activity product index of calcium oxalate were significantly higher under both diets, with a greater decline observed in the case group under the balanced diet. The estimated glomerular filtration rate (eGFR) was lower in cases. A multivariable linear regression analysis revealed a significant association between urine pH and eGFR. Conclusions: Calcium oxalate stone formers with and without enteric hyperoxaluria benefit from a balanced diet and sufficient fluid intake. The reduction in urinary oxalate excretion and the biochemical risk of recurrent calcium oxalate stone formation were even more pronounced in patients with enteric hyperoxaluria. Particular attention should be paid to low urine pH, as it is hypothesized to be a potential indicator of impaired kidney function. Full article

To address wellbore instability and the technical challenges associated with high-density water-based drilling fluid loss control in deep shale gas formations of the Sichuan-Chongqing region in China, a novel nano-micro sealant designated CLG-Seal was synthesized via molecular structural optimization. The molecular structure of newly developed CLG-Seal exhibits distinct core–shell structural characteristics. The inorganic nano-silica constitutes the rigid core of CLG-Seal, which guarantees its plugging performance. The hydrophobically associating polymer which is coated on the surface of nano-silica constructs the flexible shell of CLG-Seal, endowing the CLG-Seal with excellent gel-forming capacity, adhesion film-forming capacity, deformability and perfect dispersibility. Transmission electron microscopy and scanning electron microscopy were employed to characterize the morphology of the CLG-Seal nanomicron-scale plugging agent. The sealing performance and underlying mechanisms of CLG-Seal were subsequently evaluated via particle plugging apparatus tests, displacement experiments, and etched glass micromodel simulations. Field trials conducted in the third section of Well WY3-2-3HF validated the application effectiveness of this agent in drilling fluid systems. The results indicate that the nano-micro sealant CLG-Seal exhibits a median particle size of D₅₀ is 146 nm, which can be modulated by adjusting the synthesis conditions. The nano-micro sealant CLG-Seal significantly mitigates fluid loss in low-permeability microfractures and fissures. Notably, a concentration of merely 3% is sufficient to achieve optimal nano-micro plugging performance. The results of the mechanism study indicate that while the CLG-Seal particles are close to each other, the polymer chains with flexible long chain structure which are coated on the surface of nano-silica constructs tend to be intertwined, forming a cross-linked network structure of gel film, thereby increasing the interaction between nano-micron particles and forming an impermeable plugging film. In addition, due to the nanoscale effect, the CLG-Seal has a strong tendency to adsorb onto the surface of shale rock through hydrogen bonding with the shale matrix. The hydrophobically associating polymer with high elastic modulus and excellent mechanical properties can enhance the pressure-bearing capacity of the filter cake through elastic deformation. Therefore, these nano-micron particles can form a strong sealing film on the filter cake and at the micropores of shale rock, thereby creating a dense mud cake on the outside of the shale formation. Field trial results demonstrate that the incorporation of the nano-micro sealant CLG-Seal into the drilling fluid for the third section of Well WY3-2-3HF reduced the PPA fluid loss to 4.6 mL. This value represents a substantial reduction compared to adjacent wells and signifies a remarkable improvement over the drilling fluids previously employed in the Longmaxi Formation of this block. Furthermore, the treated drilling fluid exhibited a superior filtration control pressure capacity of 10.5 MPa. The operation was completed successfully without any lost circulation or wellbore instability, and achieved a drilling footage of 42 h with an average penetration rate of 7.81 m/h. The mud weight was reduced by approximately 0.08–0.10 g/cm³ compared to offset wells. These results confirm the excellent application efficiency of the newly developed CLG-Seal in field operations. Full article

Capillary imbibition is the process by which liquids are absorbed into porous materials as a result of capillary pressure differences at the pore scale. Accurate characterization of imbibition dynamics, particularly in the presence of gravitational potential, is essential for understanding fluid transport in diverse systems such as soil, fractured rocks, filtration media, and plant roots. This study presents systematic imbibition experiments using filter papers with pore sizes of 2.5 µm, 11 µm, and 20 µm, each inclined at 80° to quantify the influence of gravitational potential on imbibition behavior. For horizontally positioned samples, the imbibition front propagated radially and symmetrically, exhibiting a power law dependence on time. The measured temporal exponents ranged from 0.386 to 0.403, consistently lower than the theoretical value of 1/2 predicted by the Lucas–Washburn law. With increasing permeability, the temporal exponent approached the Washburn limit, indicating a marked dependence of imbibition dynamics on pore structure. For the inclined configuration at an 80° angle, the imbibition fronts remained nearly circular but exhibited a pronounced displacement of the front center toward gravity. This displacement increased with permeability, from approximately 0.497 cm for the 11 µm filter paper to 3545 cm for the 20 µm filter paper, highlighting the combined effects of permeability and gravitational potential on fluid movement. Furthermore, the advance of the imbibition front was significantly slower in the smallest pores (2.5 µm) compared to the larger ones. Experimental results were evaluated against a theoretical model proposed by Medina, demonstrating moderate quantitative agreement at early times, when gravitational potential effects are less significant. These findings confirm that both the temporal scaling exponent and the spatial evolution of the imbibition front are governed by the porous medium’s permeability and inclination angle, providing experimental evidence of deviations from ideal Washburn behavior in real porous systems. Full article

Gel plugging agents are key drilling fluid additives for maintaining wellbore stability. However, the downhole ultra-high-temperature, high-salinity environments, and developed micro-fractures in deep and ultra-deep wells pose severe challenges to the performance of gel plugging agents. To address this problem, this paper presents the preparation of a nano-micron gel plugging agent with a core–shell structure, denoted as LMS, suitable for high-temperature and high-salinity water-based drilling fluids. LMS was synthesized via emulsion polymerization, using a styrene–sodium p-styrenesulfonate copolymer as the core and 2-acrylamido-2-methylpropanesulfonic acid and methacryloyloxyethyltrimethyl ammonium chloride as the shell-modifying monomers. LMS was characterized by infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, and particle size analysis, confirming that LMS met the design expectations. Experimental results showed that after aging at 220 °C for 16 h under saturated-salt conditions, the filtration loss of the drilling fluid with 3 wt% LMS was 10.4 mL, a reduction of 57.4% compared to the base mud. Meanwhile, LMS exhibited good plugging performance in microporous membrane tests and sand bed tests. After aging at 220 °C for 16 h under saturated-salt conditions, the core plugging rate reached 95.4%. LMS can not only adsorb onto clay surfaces to increase the thickness of the hydration film, enhancing drilling fluid stability, but can also synergistically build a filter cake with clay particles to plug nano-micron pores, preventing drilling fluid infiltration into the formation. This paper provides a preparation method for a high-temperature- and high-salinity-resistant gel plugging agent with excellent plugging effects, which is expected to support safe and efficient drilling in deep and ultra-deep formations. Full article

Chronic kidney disease (CKD) is a progressive and irreversible disorder affecting over 850 million individuals globally and is associated with significant morbidity, mortality, and healthcare burden. Conventional diagnostic approaches rely on intermittent laboratory measurements, including serum creatinine, estimated glomerular filtration rate (eGFR), and urinary albumin, which provide limited temporal resolution and fail to capture dynamic physiological changes. Recent advances in wearable biosensing technologies offer new opportunities for continuous, non-invasive monitoring of biochemical and physiological markers relevant to renal function. This review provides a comprehensive analysis of wearable biosensors for CKD monitoring, focusing on sensing mechanisms (electrochemical, optical, and field-effect transistor), biofluid interfaces (sweat, interstitial fluid, and saliva), and materials engineering strategies enabling flexible, high-performance devices. Emphasis is placed on biofluid transport dynamics, analytical performance across sampling matrices, and system-level integration with wireless communication and digital health platforms. Key challenges limiting clinical translation, including biofouling, enzymatic instability, and variability in biofluid composition, are examined—alongside emerging solutions such as antifouling interfaces, synthetic recognition elements, and multimodal sensing architectures. Finally, regulatory pathways and the role of artificial intelligence in digital nephrology are discussed. This review highlights the potential of wearable biosensors to transform CKD management through continuous monitoring, early detection, and personalized therapeutic intervention. Full article

In situ leaching (ISL) of uranium faces challenges in solid–liquid separation of pregnant leaching solution, with conventional bag filters showing suboptimal performance. This study investigates wellbore and ore-bearing layer clogging in neutral ISL uranium mining, characterizing particle size distribution in the leaching solution. Results show that leaching solution particles consist mainly of clay and silt-grade debris (<200 μm). A novel hybrid separation system integrating an optimized hydro cyclone with a bag filter was developed using theoretical fluid mechanics and CFD simulations. The optimized hydro cyclone with a novel swirl chamber and conical inverted wire mesh collector achieves complete separation of particles > 60 μm and 99.9% efficiency for particles > 50 μm. The hybrid system significantly reduces operating pressure and filter bag replacement frequency from three times to once weekly, mitigating ore-bearing layer clogging. This research provides insights into particle migration mechanisms and offers an efficient solid–liquid separation solution for uranium mining operations. Full article

Efficient uranium recovery from productive leaching solutions requires accurate prediction of hydrodynamic and mass-transfer processes in ion-exchange sorption columns. In this study, a coupled multidimensional hydrodynamic and mass-transfer model is developed to investigate uranium sorption in a packed ion-exchange column equipped with a conical flow distributor. Fluid flow in the porous resin bed is described using the Forchheimer filtration law combined with the mass conservation equation, while transport of dissolved uranium species is modeled using a convective–dispersion equation coupled with a linear driving force kinetic model. The numerical solution is obtained using the fictitious domain method, which enables accurate representation of complex column geometries. The results reveal pronounced radial flow non-uniformity, incomplete flow equalization, and the formation of a ring-shaped sorption zone, indicating uneven utilization of the sorbent bed. It is shown that under practical operating conditions, mass-transfer dynamics are governed primarily by hydrodynamics rather than intrinsic sorption kinetics. The proposed model provides a practical tool for analysis and optimization of industrial uranium recovery columns. Full article

Renewable drilling fluids have attracted considerable focus due to their impact on marine ecosystems. Regulatory agencies utilize environmental evaluations to oversee the use and discharge of chemicals in marine environments. Common non-aqueous drilling fluids are derived from n-paraffin and internal olefins, with research highlighting biodiesel and ester-based fluids for their non-toxicity and biodegradability under anaerobic conditions, although their performance may vary. This study focused on Hydrotreated Vegetable Oil (HVO) as a base fluid, comparing it with an olefin fluid. Commercially sourced HVO was evaluated at a 60/40 oil-to-water ratio, typical of inverse emulsion fluids. The analysis included rheological properties, filtration, electrical stability, and ecotoxicological aspects. The HVO-based fluid exhibited strong electrical stability (>200 V), appropriate rheological behavior, thixotropic properties, and promising biodegradability, achieving 75% biodegradation in 28 days. The data show HVO’s potential for formulating effective non-aqueous inverse emulsion drilling fluids with suitable viscosity and gel strength. Full article

Background: The estimation of the postmortem interval (PMI) remains a complex challenge in forensic medicine. While macroscopic, biochemical, and molecular methods are well-documented, postmortem functional approaches at the organ level are largely underexplored. This pilot study investigated the feasibility of utilizing an isolated ex vivo kidney perfusion model to assess residual postmortem renal function—specifically glomerular filtration and tubular solute handling—as a potential chronological marker for PMI. Methods: Sixteen adult New Zealand rabbits were euthanized and randomly assigned to four postmortem interval groups (1, 5, 10, and 15 h). An unoxygenated, room-temperature crystalloid perfusion system was established to mimic natural postmortem decay. Initially, 32 kidneys were perfused; two were excluded due to anuria, resulting in 30 successfully analyzed kidneys. To strictly eliminate pseudoreplication bias, bilateral functional data were mathematically aggregated at the subject level, establishing the individual rabbit (n = 16) as the statistical unit. Results: Following statistical adjustment at the subject level, none of the measured functional parameters exhibited statistically significant chronological variation across the postmortem intervals (all p > 0.05; statistical significance defined as p < 0.05). Glomerular filtration was profoundly depressed across all groups, with adjusted inulin clearance ranging between 0.0031 and 0.0086 mL/min/g (peaking nonsignificantly at 10 h). Furthermore, active tubular reabsorption was virtually nonexistent; calculated reabsorbed loads for evaluated solutes, particularly potassium and sodium, yielded predominantly negative values. This phenomenon indicates a complete absence of physiological active reabsorption, reflecting instead a massive passive leakage of intracellular electrolytes into the tubular fluid due to cellular autolysis. Conclusions: Within this specific experimental setup, the isolated kidney perfusion model failed to demonstrate reproducible, time-dependent renal function useful for PMI estimation. These findings indirectly suggest that, unlike the prolonged supravital physiological resilience observed in skeletal muscle, highly metabolically active renal tissue rapidly loses its complex functional capacity following somatic death. Future studies exploring supravital renal function should consider targeting the immediate early postmortem period (0–1 h) or integrating advanced organ preservation techniques to unmask residual cellular capabilities. Full article

This study presents an optimized numerical and empirical modeling framework for ionic wind-driven electrostatic precipitators designed for atmospheric particulate matter (PM) removal. While traditional particle tracing models in long ducts often suffer from transient evaluation errors (the “flight time paradox”), this work introduces a Fate-based Steady-state Evaluation (FSE) method. By coupling Electrostatics, Laminar Flow, and Particle Tracing in a high-fidelity 2D axisymmetric model, we achieved a baseline validation with a Mean Absolute Error (MAE) of 5.3% compared to experimental data (20 kV, 0.5 m/s). Furthermore, a non-linear regression engine based on a physical-exponential decay function was developed to provide real-time performance predictions. The resulting hybrid model demonstrates a high scientific reliability (R² = 0.98), establishing it as a robust tool for the design and optimization of air purification systems targeting fine atmospheric aerosols (0.1–3.0 μm). In addition, the proposed Fate-based Steady-state Evaluation (FSE) method eliminates transient bias commonly observed in long-duct Lagrangian particle simulations. This methodological improvement enables statistically consistent efficiency estimation for electrohydrodynamic filtration systems and can be applied to a broad class of Computational Fluid Dynamics (CFD)-based particulate capture studies. The developed framework enables rapid design optimization of compact electrohydrodynamic filtration systems and provides a practical alternative to computationally expensive full-scale Computational Fluid Dynamics (CFD) simulations. Full article

A sustainable polymer-based filtration control system was developed for high-temperature, high-density water-based drilling fluids. The system’s rheological stability, filtration performance, and filter cake properties were evaluated under varying conditions of temperature, salinity, and density. The drilling fluid density ranged from 1.80 to 2.20 g/cm³, the temperature from 25 to 150 °C, and the NaCl mass fraction w(NaCl) = 5–20%. The results indicated that increasing fluid density resulted in a progressive increase in apparent and plastic viscosities (from 42.6/28.4 mPa·s to 65.1/47.9 mPa·s), while the yield point remained relatively stable (14.2–17.2 Pa), suggesting that high solid loading enhanced viscous dissipation without inducing structural stiffening. Filtration loss increased moderately with temperature (6.8–12.3 mL at 25–150 °C) and salinity (6.8–10.7 mL at w(NaCl) = 5–20%), whereas it decreased significantly with increasing density (13.1–9.4 mL at 1.80–2.20 g/cm³), indicating a density-dominated filtration regime. At 120 °C, w(NaCl) = 12%, and 2.00 g/cm³, the developed system achieved a low filtration loss of 8.4 mL, outperforming three representative conventional filtration-control systems, including starch-based, sulfonated asphalt-based, and polymer-based technologies. Filter cake analysis revealed that increasing density facilitated the packing of multi-scale solids, reducing filter cake thickness from 1.62 mm to 0.98 mm and permeability from 1.34 × 10⁻¹⁵–4.05 × 10⁻¹⁶ m², while significantly improving resistance to erosion and compression. These findings demonstrate that the combination of interfacial stabilization and filter cake densification offers a robust and controllable filtration solution for high-temperature, high-density drilling environments, presenting a promising approach for drilling fluid systems in challenging conditions. Full article

Non-Newtonian weighted fracturing fluids are used to carry out hydraulic fracturing operations into the deep and ultra-deep earth for oil and gas extraction, though their flow and friction drag characteristics are largely unknown. This study aims to understand the abovementioned characteristics. An engineering-oriented cost-effective numerical scheme is deployed, incorporating LES with a generalized Newtonian fluid constitutive equation, for predicting the non-Newtonian pipe flow and friction drag coefficient C_f. The weighted fracturing fluid is described as a power-law fluid, i.e., viscosity $\mu \left(\dot{\gamma }\right)=K{\dot{\gamma }}^{n-1}$, where both K and n are coefficients related to fluid rheology, and $\dot{\gamma }$ is the shear rate. The influences of fluid density ρ, mean velocity U and pipe diameter D, as well as K and n on C_f were documented and compared with a water pipe flow. It was found that C_f = f₁ (K, n, ρ, U, D) may be reduced to C_f = f₂ (Re_g), where the scaling factor Re_g = ρU²⁻ⁿDⁿ/(K8ⁿ⁻¹) is the generalized Reynolds number. This scaling law can reasonably well predict the friction drag variation in the pipe flow of non-Newtonian weighted fracturing fluids throughout a range of interests and engineering applications. Full article