Search Results (2,273)

Background/Objectives: Fluid overload in critically ill patients is linked to adverse outcomes. While resuscitation strategies are well established, guidance for the de-resuscitation phase remains limited. This study aimed to identify clinical factors associated with diuretic response and achieving negative fluid balance (FB) in critically ill patients. Methods: We conducted a single-center, retrospective cohort study of ICU patients who received intravenous furosemide between 2017 and 2023. A CHAID (Chi-square Automatic Interaction Detector) decision tree identified clinical variables associated with fluid removal after the first dose, and a mixed-effects model analyzed repeated measurements. Results: The cohort comprised 1764 patients over 6632 ICU days. Mean arterial pressure (MAP) was the strongest predictor of negative FB. MAP ≤ 75 mmHg yielded minimal negative FB (−33 ± 1054 mL/24 h); MAP 75–90 mmHg yielded intermediate negative FB (−467 ± 1140 mL/24 h); and MAP > 90 mmHg produced the greatest negative FB (−899 ± 1415 mL/24 h; p < 0.001). Secondary associations varied by MAP: creatinine at low MAP, blood urea nitrogen at mid-range MAP, and SOFA score at high MAP, all inversely related to negative FB. In mixed-effects analyses, each 1 mmHg MAP increase was associated with 23.3 mL greater fluid removal (p < 0.001). Independent factors linked to reduced negative FB included vasopressor use (noradrenaline), elevated creatinine, and higher SOFA scores. Conclusions: In this cohort, MAP was significantly associated with the likelihood of achieving a negative fluid balance during de-resuscitation. Conversely, vasopressor use, renal dysfunction, and higher illness severity were linked to reduced diuretic responsiveness. These findings support individualized de-resuscitation strategies. Full article

To investigate the influence of particle characteristics on wear in slurry pump flow-through components, this study established a computational fluid dynamics-discrete element method (CFD-DEM) coupled with the Archard wear model for numerical simulation of solid-liquid two-phase flow characteristics and wear mechanisms within the pump. Focusing on the correlation between wear contour distribution and particle collision frequency, the study systematically analyzed the influence mechanisms of particle concentration, size distribution, and shape on wear patterns within the pump. The reliability of the coupled model was validated through external characteristic tests. Results indicate that wear severity on both the impeller and volute increases significantly with rising particle concentration, while wall particle collision frequency exhibits a positive correlation with concentration. Particles of 1.5 mm diameter cause the most severe localized wear on the impeller, whereas the presence of mixed particles partially mitigates the wear effect of larger particles. Both total and localized wear on the volute peak at a particle diameter of 1 mm. Low-sphericity particles intensified overall wear on both the impeller and volute; while high-sphericity particles reduced overall wear, they induced more severe localized wear on the impeller. Volute localized wear was most pronounced at a sphericity of 0.84. This study elucidates the mechanism by which particle characteristics influence wear on slurry pump flow-through components, providing a theoretical basis for optimizing slurry pump design. Full article

Energetic powder processing includes comminution, sieving, drying, conveying, mixing, and packaging, all of which determine product performance and safety. With growing requirements for efficiency and reliability, numerical simulation has become essential for analyzing mechanisms, optimizing parameters, and supporting equipment design. This review summarizes recent progress in simulation techniques such as the discrete element method (DEM), computational fluid dynamics (CFD), and multi-scale coupling while also evaluating their predictive capabilities and limitations across various unit operations and safety concerns such as electrostatic hazards. It, thus, establishes the core “property–parameter–performance” relationships and clarifies mechanisms in multiphase flow, energy transfer, and charge accumulation, and highlights the role of symmetry in improving simulation efficiency. By highlighting persistent challenges, this work lays a foundation for future research, guiding the development of theoretical frameworks and practical solutions for advanced powder processing. Full article

Hot-fluid injection in thermal-enhanced oil recovery (thermal-EOR, TEOR) imposes temperature-driven volumetric strains that can substantially alter in situ stresses, fracture geometry, and wellbore/reservoir integrity, yet existing TEOR modeling has not fully captured coupled thermo-poroelastic (thermo-hydro-mechanical) effects on fracture aperture, fracture-tip behavior, and stress rotation within a displacement discontinuity method (DDM) framework. This study aims to examine the influence of sustained hot-fluid injection on stress redistribution, hydraulic-fracture deformation, and fracture stability in thermal-EOR by accounting for coupled thermal, hydraulic, and mechanical interactions. This study develops a fully coupled thermo-poroelastic DDM formulation in which fracture-surface normal and shear displacement discontinuities, together with fluid and heat influx, act as boundary sources to compute time-dependent stresses, pore pressure, and temperature, while internal fracture fluid flow (Poiseuille-based volume balance), heat transport (conduction–advection with rock exchange), and mixed-mode propagation criteria are included. A representative scenario considers an initially isothermal hydraulic fracture grown to 32 m, followed by 12 months of hot-fluid injection, with temperature contrasts of ΔT = 0–100 °C and reduced pumping rate. Results show that the hydraulic-fracture aperture increases under isothermal and modest heating (ΔT = 25 °C) and remains nearly stable near ΔT = 50 °C, but progressively narrows for ΔT = 75–100 °C despite continued injection, indicating potential injectivity decline driven by thermally induced compressive stresses. Hot injection also tightens fracture tips, restricting unintended propagation, and produces pronounced near-fracture stress amplification and re-orientation: minimum principal stress increases by 6 MPa for ΔT = 50 °C and 10 MPa for ΔT = 100 °C, with principal-stress rotation reaching 70–90° in regions adjacent to the fracture plane and with markedly elevated shear stresses that may promote natural-fracture activation. These findings show that temperature effects can directly influence injectivity, fracture containment, and the risk of unintended fracture or natural-fracture activation, underscoring the importance of temperature-aware geomechanical planning and injection-strategy design in field operations. Incorporating these effects into project design can help operators anticipate injectivity decline, improve fracture containment, and reduce geomechanical uncertainty during long-term hot-fluid injection. Full article

In the pursuit of cleaner and more efficient internal combustion engines, dual-fuel strategies combining diesel and hydrogen are gaining increasing attention. This study employs detailed computational fluid dynamics (CFD) simulations to investigate the behaviour of pilot diesel injections in dual-fuel diesel–hydrogen engines. The study aims to characterize spray formation, ignition delay and early combustion phenomena under various energy input levels. Two combustion models were evaluated to determine their performance under these specific conditions: Tabulated Well Mixed (TWM) and Representative Interactive Flamelet (RIF). After an initial numerical validation using dual-fuel constant-volume vessel experiments, the models are further validated using in-cylinder pressure measurements and high-speed natural combustion luminosity imaging acquired from a large-bore optical engine. Particular attention was given to ignition location due to its influence on subsequent hydrogen ignition. Results show that both combustion models reproduce the experimental behavior reasonably well at high energy input levels (EILs). At low EILs, the RIF model better captures the ignition delay; however, due to its single-flamelet formulation, it predicts an abrupt ignition of all available premixed charge in the computational domain once ignition conditions are reached in the mixture fraction space. Full article

This study presents a quantitative simulation analysis of hydrogen-enriched methane (HENG) storage with nitrogen as the cushion-gas in a depleted gas reservoir by varying three key operational parameters: the injection/withdrawal period, hydrogen blending ratio (5–20%), and injection depth. Ten injection–withdrawal cycles were modeled for each scenario, and performance was evaluated using cycle-averaged and cumulative hydrogen purity, recovery factors, and the mixing zone size. Extending the injection period increased hydrogen purity to 20.00–20.26% and reduced nitrogen to 0.001–0.003%, but recovery decreased from 65.63 to 53.83–41.09% due to enhanced dispersion and residual trapping. The blending ratio was the dominant control: 20% blending yielded 19.9–20.0% purity with nitrogen as low as 0.00–0.03%, whereas 5–10% blending produced lower purity but minimized nitrogen production to 0.97–1.08%. Injection depth affected nitrogen recovery more than purity, increasing from 0.72–1.20% (upper) to 1.46–1.61% (lower), along with thicker mixing zones. Final mixing zone size ranged from 3176 to 5546 blocks, with smaller zones consistently linked to higher purity and lower nitrogen breakthrough. The shut-in period further reduced nitrogen recovery from 6.49 to 1.33% and stabilized mixing behavior. Overall, minimizing late-cycle mixing zone thickness is essential for maintaining HENG storage performance. Although this study provides quantitative insights into HENG operational strategies, the use of a homogeneous grid and simplified fluid properties limits representation of geological heterogeneity and reactive processes. Future work will incorporate heterogeneity and reaction modeling into field-scale simulations to validate and refine these operating strategies for practical deployment. Full article

Geothermal fluids are the main carrier of hydrothermal geothermal resources. Identifying the differences in geothermal fluids in different types of reservoirs is a prerequisite and fundamental for the efficient development of geothermal resources and is of great significance for scientific research on geothermal resources. The North China Plain contains a typical carbonate thermal reservoir, and in this paper, the hydrochemical, isotopic, and redox characteristics of the geothermal fluids in sandstone and carbonate reservoirs are studied to obtain the differences in the geothermal fluids in the Rongcheng geothermal field in Xiong’an New Area. The results indicate that the geothermal fluids in the sandstone and carbonate reservoirs are mainly supplied by atmospheric rainfall, and the hydrochemical type is mainly Cl-Na type. By comparing and analyzing the stable isotope (O, H, C, S, and Sr) characteristics of the two types of geothermal fluids, it is found that the variation range of δ13C values for two types of sandstone thermal storage geothermal fluids was found to be −10.6‰~−12.8‰, while the variation range of δ¹³C values for carbonate thermal storage geothermal fluids was −3.3‰~−7.5‰. The ⁸⁷Sr/⁸⁶Sr ratio of sandstone thermal storage geothermal fluids was distributed between 0.708–0.718, and the ⁸⁷Sr/⁸⁶Sr ratio of carbonate thermal storage geothermal fluids was distributed between 0.708–0.713. The range of δ³⁴S values for sandstone thermal storage geothermal fluids was +9.46‰~+10.5‰, and the range of δ³⁴S values for carbonate thermal storage geothermal fluids was +24.84‰~+34.49‰. The two types of geothermal fluids have been subjected to varying degrees of oxidation-reduction, and their cycling and mixing characteristics are different. This has resulted in the formation of relatively oxidized geothermal fluids in the sandstone geothermal reservoir and relatively reduced geothermal fluids in the carbonate geothermal reservoir. In future development and utilization of geothermal resources, paying attention to the basic characteristics of the geothermal fluids in different reservoirs and identifying the differences in different geothermal fluids can further improve the efficiency of geothermal resource development and utilization. Full article

The Chaijiagou Mo deposit (0.11 Mt Mo @ 0.07%) is located along the northern margin of the North China Craton. This study integrates ore geology, S–Pb–He–Ar–H–O isotopes, and fluid inclusion (FI) analyses to constrain the sources of ore-forming fluids and metals, as well as mineralization mechanisms. Three principal inclusion types were identified: liquid-rich, vapor-rich, and saline FIs. Microthermometry documents a progressive decline in homogenization temperatures and salinities from early to late mineralization stages: Stage 1 (360–450 °C; 5.3–11.3 and 35.4–51.5 wt.% NaCl equation), Stages 2.1–2.2 (320–380 °C and 260–340 °C; 5.4–11.8 and 33.8–44.5 wt.% NaCl equation), and Stage 4 (140–200 °C; 0.4–3.9 wt.% NaCl equation). Noble gas and stable isotope data reveal that the ore-forming fluids were initially dominated by crustally derived magmatic–hydrothermal components with a minor mantle contribution, subsequently experiencing significant meteoric water input. S–Pb isotopic compositions demonstrate a genetic relationship between mineralization and the ore-bearing granite porphyry, indicating a magmatic origin for both sulfur and lead. Fluid–rock interactions and fluid boiling were the dominant controls on molybdenite and chalcopyrite deposition during Stage 2, whereas mixing with meteoric waters triggered galena and sphalerite precipitation in Stage 3. Full article

Lithuania covers the deepest parts of the Baltic basin and contains many reservoirs that have been explored for Hydrocarbon production and gas storage projects, including CO₂ and hydrocarbon gas storage. Studies have also been conducted to assess the storage potential of these reservoirs for gases like CO₂ and Hydrogen. In the studies, four saline aquifers, including Syderiai, Vaskai, and D11, and depleted hydrocarbon reservoirs in the Gargzdai structure were evaluated for potential CO₂ storage. However, the long-term fate of these gases’ migration at the field scale has not been reported previously. In response to the existing gap, this study aims to evaluate the risks and challenges associated with subsurface CO₂ and Hydrogen storage by conducting numerical simulations at two injection rates, of fluid migration, pH variations, and geomechanical responses using the tNavigator platform, complemented by laboratory experiments on outcrops representative of Syderiai formation, to achieve a detailed understanding of geochemical interactions between rocks and fluids. The results reveal distinct gas-specific behaviors: CO₂ exhibits enhanced solubility trapping, density-driven convective mixing, and pronounced pH reduction, whereas Hydrogen demonstrates rapid buoyant migration, higher pressure buildup, and negligible geochemical reactivity. Both gases demonstrate short-term storage viability in the Syderiai aquifer under the modeled conditions, with pressure and total vertical stress remaining below the bottom-hole pressure limit of 450 bars. This integrated simulation and experimental study enhances our understanding of Lithuanian reservoirs for the safe, long-term storage of both CO₂ and Hydrogen. Full article

Systematic investigation into the structural integrity of adjustable ejectors, particularly concerning thermal–fluid–structural (TFS) coupling, is currently lacking. Utilizing the Workbench platform, this study performs unidirectional steady-state TFS coupling numerical simulation of the adjustable air ejector under off-design conditions to systematically analyze its internal flow characteristics and structural mechanical responses across various needle openings. The results show that thermal load is the dominant factor governing the ejector’s structural stress and deformation. The overall deformation is primarily characterized by axial elongation, with the maximum thermal deformation localized at the ejector’s exit section. The nozzle exit is identified as the primary structural weak point, exhibiting the highest local stress, which peaks at 196.8 MPa when the needle opening is minimized. Shock train structures extending from the nozzle’s divergent section into the mixing chamber, coupled with the axial displacement of the needle, significantly influence the ejector’s thermal deformation and thermal stress. Based on the thermally dominated stress mechanism identified, this study proposes a composite nozzle design utilizing a nickel-plated Invar alloy substrate. This material fully leverages Invar alloy’s low thermal expansion to mitigate thermal stress and deformation while the nickel plating ensures corrosion resistance, thereby significantly enhancing the nozzle’s mechanical properties and operational reliability in thermal environments. The findings of this analysis are applicable to off-design evaluations under unidirectional steady-state coupling conditions, providing a valuable reference for the structural design and strength optimization of similar ejectors operating in high-temperature, unsteady environments. Full article

Objectives: The Eight-chop technique is a mechanically based nuclear segmentation method designed to improve surgical efficiency and reduce intraocular tissue stress during phacoemulsification. Early postoperative aqueous flare serves as an objective indicator of surgical invasiveness, whereas corneal endothelial cell density (CECD) loss represents a structural measure of endothelial injury. Although both parameters are clinically important, their relationship has not been systematically investigated in the context of this newer mechanical fragmentation approach. Methods: This prospective observational study included 118 eyes from 70 non-diabetic patients undergoing uncomplicated Eight-chop phacoemulsification. Aqueous flare was measured preoperatively and at postoperative Day 1, Day 7, Week 7, and Week 19 using laser flare photometry. CECD was evaluated preoperatively and at Weeks 7 and 19. Changes over time were analyzed using paired t-tests. Linear mixed-effects models (random intercept = patient ID) were constructed to assess predictors of CECD loss and postoperative intraocular pressure (IOP) reduction. Explanatory variables included Day 1 flare, age, preoperative CECD, nucleus hardness (Emery-Little grade), cumulative dissipated energy (CDE), and irrigation fluid volume. Results: Postoperative flare increased significantly at all time points (all p < 0.001), peaking on Day 7 (16.7 ± 9.21 photon counts/ms). CECD loss was extremely small, averaging 1.38% at Week 7 and 1.46% at Week 19. In mixed-effects models, Day 1 flare was not associated with CECD loss at Week 7 (p = 0.35) or Week 19 (p = 0.85). Significant predictors of CECD loss included Emery-Little grade (p = 0.004 at Week 7; p = 0.025 at Week 19), with borderline contributions from CDE and irrigation volume. IOP decreased significantly at Weeks 7 and 19; however, Day 1 flare did not predict IOP reduction. Conclusions: Eight-chop phacoemulsification produced uniformly low postoperative inflammation and exceptionally small corneal endothelial cell loss. Early postoperative flare did not predict CECD loss, suggesting that the Eight-chop technique provides a highly standardized, low-invasiveness surgical environment. These findings suggest that the Eight-chop technique lowers ultrasound energy requirements and may help reduce corneal endothelial stress relative to standard phacoemulsification. Full article

Efficient mixing in stirred tanks is essential for chemical and biochemical processes. Tubular baffles offer potential energy savings and multifunctionality (e.g., as heat exchangers); however, their interaction with common impeller types is not well understood. This study uses computational fluid dynamics (CFD) simulations to evaluate the hydrodynamic performance of a novel tubular baffle design compared to conventional flat baffles with three impellers: a Rushton turbine (RT), a pitched blade turbine (PBT), and a hydrofoil (HE3). Dimensionless analysis (power number, N_P; and pumping number, N_Q), flow visualization, and vorticity dynamics were employed. The results show that, by attenuating large-scale recirculation, tubular baffles reduce power consumption by 64%, 13%, and 23% for the HE3, PBT, and RT, respectively. However, the HE3 impeller experienced a 30% decrease in pumping capacity, which confined the flow to the lower tank. The PBT showed a 10% increase in N_Q and intensified bottom circulation. The RT uniquely generated distributed, high-intensity turbulence along the baffle height while maintaining its characteristic dual-loop structure. The analysis critiques the local pumping efficiency metric and advocates for a global flow assessment. The HE3 is optimal for efficient bulk blending at low power; the PBT is optimal for strong bottom circulation processes; and the RT is optimal for applications requiring enhanced interfacial processes, where baffles serve a dual function. This work provides a framework for selecting energy-efficient agitation systems by coupling impeller performance with global tank hydrodynamics. Full article

There exists an east–west trending albitite (breccia) zone, approximately 400 km in length, closely related to gold mineralization, in Devonian strata in the South Qinling tectonic belt. The genesis and formation age of these albitite (breccia) are of great significance for understanding gold enrichment mechanisms and guiding future exploration. Past studies have mainly focused on the Fengxian–Taibai area in the western segment of the albitite (breccia) zone, whereas the eastern segment remains significantly understudied. In this study, a systematic field investigation, as well as petrology, geochemistry, and accessory-mineral geochronology studies were conducted on albitites and albitite breccias in the Shangnan area, the eastern segment of the albitite (breccia) zone. The results show that the albitites are interlayered with or occur as lenses within Devonian clastic rocks. The albitite breccias are mostly enclosed in albitite and Devonian strata, and the clasts within are subangular, uniform in type, and exhibit minimal displacement. Both albitites and albitite breccias exhibit similar trace-element characteristics and detrital zircon age spectra to those of Devonian clastic rocks. Abundant hydrothermal monazites with U–Pb ages ranging from 260 to 252 Ma are present in both albitites and albitite breccias but absent in Devonian clastic rocks. Collectively, these results indicate that the albitites in the Shangnan area are of hydrothermal metasomatic origin, while the albitite breccias record hydraulic fracturing and cementation, and both are products of the same fluid activity event in the Late Permian. We propose that albitite (breccia) zones in the South Qinling tectonic belt were formed under distinct tectonic settings during different evolution stages of the Late Paleozoic Mianlüe Ocean. Specifically, the albitites (breccias) in the Shangnan area are products of thorough metasomatism, local fracturing, and cementation of Devonian clastic rocks by mixed fluids, which ascended along the Fengzhen–Shanyang Fault coeval with the emplacement of magmatic rocks related to subduction of the Mianlüe Ocean. In contrast, the albitite breccias in the Fengxian–Taibai area are the result of fluid activity during the transition from regional compression to extension after the closure of the Mianlüe Ocean. Full article

Sensitive reservoirs with high clay content commonly suffer from severe water/salt sensitivity and water-lock damage during conventional water-based hydraulic fracturing, which reduces fracture conductivity and post-stimulation performance. To address this issue, we propose a CO₂ quasi-dry fracturing approach that combines the low-damage feature of CO₂ dry fracturing with the proppant-carrying capacity of a water-based system under atmospheric sand mixing conditions. Taking Well S in the Lulehe Formation (Qaidam Basin) as a case study, we conducted reservoir sensitivity evaluation, laboratory fluid/rock interaction tests, and a field trial with microseismic monitoring. The reservoir is dominated by water and salt sensitivity, indicating high risk of damage when using conventional fluids. Laboratory results show that the CO₂ quasi-dry system improves swelling inhibition and enhances core structural stability compared with fresh water. Field implementation was operationally stable and generated an effective stimulated reservoir volume on the order of 10⁵ m³; post-fracturing oil production increased relative to nearby offset wells with a high flowback ratio. The results demonstrate that CO₂ quasi-dry fracturing provides an effective low-damage stimulation option for strongly sensitive reservoirs and can be transferred to similar formations. Full article

The primary objective of this work is to provide new solutions to increase impact protection, using a three-dimensional textile imbibed with a shear-thinning fluid. An extensive analysis showed a scarcity of research papers related to the damping capacity of deformable porous materials imbibed with non-Newtonian fluid. No studies were found for shear-thinning fluid flow inside highly compressible foams or other soft, porous materials. The damping capacity of the imbibed material was evaluated using impact with a dropping weight. Polyvinyl alcohol solution mixed with water was used for imbibition of a three-dimensional textile. Hydrophilized carbon nanofibers were also added to the solution to augment the shear-thinning behavior. The measured impact force for imbibed samples showed an important reduction compared to the impact force for the dry material. This research does not focus on flow phenomena at the microstructural level but instead aims to highlight the macroscopic attenuation effect that occurs during the compression of the imbibed material. Full article