Search Results (4,202)

The low thermal conductivity of phase change material (PCM) critically constrains the cooling performance of PCM-based battery thermal management system (BTMS). To address this limitation, embedding high-thermal-conductivity fins into PCM was recently explored. However, it may increase the overall BTMS mass, degrading vehicle performance. Therefore, a quantitative evaluation of the effects of fin design on cooling performance and system mass is required. In this study, the effects of fin design factors in a PCM–fin structured BTMS on the maximum cell temperature and BTMS mass was analyzed using design of experiments (DoE) and analysis of variance (ANOVA). To characterize BTMS thermal behavior, a numerical model was developed by applying thermal fluid partial differential equations (PDEs) with the enthalpy–porosity method to represent the phase change of the PCM. Fin number, thickness, and angle were selected as design factors; responses were calculated through thermal fluid analysis. The results showed a trade-off between thermal performance and mass across all design factors. The number of fins had the greatest effect on maximum cell temperature (78.27%) but less on mass (28.85%). Fin thickness moderately affected temperature (16.71%) but strongly increased mass (63.93%). Fin angle had minimal impact, 4.10% on temperature and 3.10% on mass. Full article

Glycolipids are structurally diverse amphiphilic molecules with potential as non-petrochemical-derived bioproducts, including surfactants, emulsifiers, and antioxidants. The different bioactivities associated with this range of glycolipid structures also present opportunities for dietary supplements, cosmetics, and pharmaceuticals. Marine glycolipids are underexplored due to challenges with purification and structural characterisation. Analytical approaches enabling efficient sample purification, isolation, and identification of target glycolipids are crucial to determining the bioactivity and functions of organisms such as shellfish and seaweed. This review summarises advances in analytical methods applicable to marine glycolipids, including extraction and enrichment methods tailored to specific subclasses. Thin-layer chromatography (TLC)-based rapid detection techniques developed for specific subclasses in complex biological samples are discussed, alongside structure identification methods based on liquid chromatography (LC)–electrospray ionisation (ESI)–tandem mass spectrometry (MS/MS). Hydrophilic interaction liquid chromatography (HILIC), reverse-phase liquid chromatography (RPLC), and supercritical fluid chromatography (SFC) coupled with MS detection are reviewed for their application to glycolipids. The application of two-dimensional liquid chromatography (2D-LC) and advanced MS-based approaches that facilitate both the rapid resolution and comprehensive characterisation of molecular species are also reviewed. Full article

In recent years, research into the synthesis of innovative biomaterials for prosthetic applications has been increasingly growing. In particular, there is a demand for biomaterials with an excellent biocompatibility that can interact with biological fluids. This study involved the development of new silica (SiO₂)-based composite materials using the sol–gel technique and functionalization with ferulic acid (FA), a natural phenolic compound renowned for its biological properties. The synthesis involved controlling the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in acidic and alcoholic environments to incorporate ferulic acid into the sol phase matrix at different weight compositions (5, 10, 15, and 20 wt%). Fourier transform infrared spectroscopy analyses (FTIR) confirmed the successful incorporation of the bioactive compound, and in vitro tests revealed a good cytocompatibility and controlled ferulic acid release over time. These results demonstrate that the developed material shows promise as a bioactive coating for orthopedic prostheses, improving bone integration and reducing undesirable post-operative phenomena. Full article

The compound lift and thrust Vertical Take-Off and Landing (VTOL) fixed-wing Unmanned Aerial Vehicle (UAV) has generated considerable interest in configuration research due to its unique application advantages. This investigation examines the aerodynamic phenomena between the rotors and the main wings, as well as canards, during the transition phase through numerical simulations, thereby advancing the understanding of canard configurations in such UAVs. Based on a systems engineering approach, a 6 kg canard-configured compound lift and thrust VTOL fixed-wing UAV was preliminarily designed for evaluation. Computational Fluid Dynamics (CFD) methods were employed to study the aerodynamic interference under various freestream velocities and rotor speeds during the transition phase. The reliability of the CFD methodology was validated through rotor thrust experiments. Simulations were conducted with freestream velocities ranging from 3 m/s to 15 m/s and rotor speeds from 4000 to 10,000 RPM. The results indicate that the interference of the rotating rotor during the transition phase initially reduces lift, then increases lift, and finally reduces lift again for the wing, while it increases lift for the canard. This phenomenon results from the coupled influence of freestream velocity and rotor-induced flow effects. Full article

In order to solve the problem of low thermal efficiency of a 130 t/h industrial circulating fluidized bed boiler, a computational particle fluid dynamic approach was used in this work to study two-phase gas–solid flow, heat transfer, and combustion. The factors influencing coal particle size distributions, air distribution strategies, and operational loads are addressed. The results showed that particle distribution exhibits “core–annulus” flow with a dense-phase bottom region and dilute-phase upper zone. A higher primary air ratio (0.8–1.5) enhances axial gas velocity and bed temperature but reduces secondary air zone (2.5–5.8 m) temperature. A higher primary air ratio also decreases outlet O₂ mole fraction and increases fly ash carbon content, with optimal thermal efficiency at a ratio of 1.0. In addition, as the coal PSD decreases and the load increases, the overall temperature of the furnace increases and the outlet O₂ mole fraction decreases. Full article

Background: The aims of this paper are to examine the impact of the COVID-19 pandemic on the non-rational use of antibiotics and potential alterations in the antibiotic resistance profiles of multi-drug resistant (MDR) isolates of Klebsiella pneumoniae (KPN), Pseudomonas aeruginosa (PAE), and Acinetobacter baumannii (ABA). Material and Methods: This study was conducted at the tertiary University Hospital “Dr Dragisa Misovic-Dedinje” (Belgrade, Serbia) and was divided into three periods: pre-pandemic (1.4.2019–31.3.2020, period I), COVID-19 pandemic (1.4.2020–31.3.2021, period II), and COVID-19 pandemic-second phase (1.4.2021–31.3.2022, period III). Cultures were taken from each patient with clinically suspected infection (symptoms, biochemical markers of infection). All departments of the hospital were included in this study. Based on the source, all microbiological specimens were divided into 1° blood, 2° respiratory tract (tracheal aspirate, bronchoalveolar lavage fluid, throat, sputum), 3° central-line catheter, 4° urine, 5° urinary catheter, 6° skin and soft tissue, and 6° other (peritoneal fluid, drainage sample, bioptate, bile, incisions, fistulas, and abscesses). After the isolation of bacterial strains from the samples, an antibiotic sensitivity test was performed for each individual isolate with the automated Vitek^® 2 COMPACT. Antibiotic consumption testing was performed by the WHO guideline equations (ATC/DDD). Results: A total of 2196 strains of KPN, PAE, and ABA from 41,144 hospitalized patients were isolated (23.6% of the number of total isolates). The number of ABA isolates statistically increased (p = 0.021), while the number of PAE isolates statistically decreased (p = 0.003) during the pandemic. An increase in the percentage of MDR strains was observed for KPN (p = 0.028) and PAE (p = 0.027). There has been an increase in the antibiotic resistance of KPN for piperacillin–tazobactam, the third and fourth generations of cephalosporins (ceftriaxone, ceftazidime, and cefepime), all carbapanems (imipenem, meropenem, and ertapenem), and levofloxacin; of PAE for imipenem; and of ABA for amikacin. Total antibiotic consumption increased (from 755 DBD to 1300 DBD, +72%), especially in the watch and reserve group of antibiotics. The highest increases were noted for vancomycin, levofloxacin, azithromycin, and meropenem. MV positively correlated with the increased occurrence of MDR KPN (r = 0.35, p = 0.009) and MDR PAE (r = 0.43, p = 0.009) but not for MDR ABA (r = 0.09, p = 0.614). There has been a statistically significant increase in the Candida sp. isolates, but the prevalence of Clostridium difficile infection remained unchanged. Conclusions: The COVID-19 pandemic has influenced the increase in total and MDR strains of KPN, ABA, and PAE and worsened their antibiotic resistance profiles. An increase in the consumption of both total and specific antibiotics was observed, mostly of fluoroquinolones and carbapenems. A positive correlation between the number of patients on MV and an increase in MDR KPN and MDR PAE strains was noted. It is necessary to adopt and demand the implementation of appropriate antimicrobial stewardship interventions to decrease the resistance of intrahospital pathogens to antibiotics. Full article

Metastable titanium alloys have been developed for biomedical use due to their lower elastic modulus, combined with high strength, good ductility, and excellent corrosion resistance. In this study, the electrochemical corrosion resistance of the alternative Ti-23.6Nb-5.1Mo-6.7Zr alloy was investigated. The alloy was initially homogenized at 1000 °C for 24 h and then tested under different processing conditions: 90% cold rolling; 90% cold rolling followed by annealing at 950 °C for 1 h and water quenching; and 90% cold rolling followed by aging at 300 °C, 400 °C, and 500 °C for 4 h each. Electrochemical behavior was assessed using anodic polarization, open circuit potential (OCP), and electrochemical impedance spectroscopy (EIS) tests in a synthetic solution (Ringer’s solution) to simulate body fluid. The obtained results demonstrate the stability of the passive film formed of the conventional and modified alloys, considering long-term use in the human body, regardless of the volumetric fraction and phase distribution across the various processing routes studied as β, α, α″ and ω. The electrochemical parameters, combined with Young’s modulus and hardness of the alternative alloys, enable the definition of a multicriteria selection method of the most suitable mechanical process routes to be used. The application focused on components of functional femoral stems. Full article

Hydrogel-based biosensors are commonly used in diagnostic applications. However, their performance remains constrained by slow analyte diffusion within polymer matrices, particularly when larger biomolecules are involved. Concave hydrogel geometries present a promising solution to enhance diffusion rates through increased surface area. However, the interfacial dynamics governing their formation must be studied. In this research, we investigated the interfacial dynamics that influence the formation of concave hydrogel discs fabricated by a simple pipetting method. We characterized the fluid interactions occurring during droplet deposition of alginate and CaCl₂ solutions. A three-phase flow model incorporating confocal microscopy validation was employed to simulate time-dependent interfacial behaviors. Concave hydrogel discs fabricated with alginate-first deposition exhibited 83% larger surface area compared to hemispherical counterparts at a CaCl₂: alginate volume ratio of one. Increasing the volume ratio further enhanced both surface area and diameter, though this highlighted limitations for microscopy-based detection. According to our results, reaction speed in alginate concave hydrogel discs can be controlled by varying the volume of CaCl₂ solution while keeping the volume of alginate solution constant, which changes the surface area while maintaining constant hydrogel volume. Full article

Background: Intrahepatic cholestasis of pregnancy (ICP) is the most common reversible liver disorder linked to pregnancy, characterised by pruritus and elevated serum bile acids (BAs). Condition severity correlates with increased maternal and neonatal complications, and recent evidence highlights a significantly elevated risk of adverse perinatal outcomes, including stillbirth, when BA > 100 µmol/L. Methods: This retrospective study, conducted at a tertiary perinatology centre between 2019 and 2023, was performed in two phases. In the first phase, baseline group characteristics and pregnancy outcomes were compared between ICP and non-ICP (control) groups. In the second phase, outcomes were analysed across three ICP severity subgroups: mild (BA < 40 µmol/L), moderate (BA 40–99 µmol/L), and severe (BA ≥ 100 µmol/L). Results: A total of 210 patients diagnosed with ICP and 24,177 controls were included in the analysis. After multivariable regression, the results indicated that patients with severe ICP (BA ≥ 100 µmol/L) experienced significantly worse perinatal outcomes compared to those with mild or moderate disease: spontaneous preterm birth occurred in 26.7% of cases (p = 0.002), iatrogenic preterm birth in 36.7% (p < 0.001), meconium-stained amniotic fluid in 43.3% (p = 0.001), and neonatal intensive care unit (NICU) admission in 23.3% (p = 0.006). This subgroup also had the lowest mean birth weight (2830 g, p < 0.001). Notably, no stillbirths were recorded in any of the subgroups. Compared to controls, no major differences in maternal characteristics were noted, except in pregnancies conceived via in vitro fertilisation (IVF, p = 0.012) and those complicated by gestational diabetes (p = 0.040), both showing elevated risk for ICP development. Conclusions: This study confirms an association between ICP and increased perinatal complications, with severity of disease correlating with poorer outcomes. The findings highlight the need for standardised BA testing and improved strategies for perinatal management. Full article

A methane-air premixed gas explosion is one of the most destructive disasters in the process of coal mining, and the dynamic coupling between the shock wave triggered by the explosion and the surrounding rock of the roadway can lead to the destabilization of the surrounding rock structure, the destruction of equipment, and casualties. The aim of this study is to systematically reveal the propagation characteristics of the blast wave, the spatial and temporal evolution of the wall load, and the damage mechanism of the surrounding rock by establishing a two-way fluid-solid coupling numerical model. Based on the Ansys Fluent fluid solver and Transient Structure module, a framework for the co-simulation of the fluid and solid domains has been constructed by adopting the standard $k-\epsilon$ turbulence model, finite-rate/eddy-dissipation (FR/ED) reaction model, and nonlinear finite-element theory, and by introducing a dynamic damage threshold criterion based on the Drucker–Prager and Mohr–Coulomb criteria. It is shown that methane concentration significantly affects the kinetic behavior of explosive shock wave propagation. Under chemical equivalence ratio conditions (9.5% methane), an ideal Chapman–Jouguet blast wave structure was formed, exhibiting the highest energy release efficiency. In contrast, lean ignition (7%) and rich ignition (12%) conditions resulted in lower efficiencies due to incomplete combustion or complex combustion patterns. In addition, the pressure time-history evolution of the tunnel enclosure wall after ignition triggering exhibits significant nonlinear dynamics, which can be divided into three phases: the initiation and turbulence development phase, the quasi-steady propagation phase, and the expansion and dissipation phase. Further analysis reveals that the closed end produces significant stress aggregation due to the interference of multiple reflected waves, while the open end increases the stress fluctuation due to turbulence effects. The spatial and temporal evolution of the strain field also follows a three-stage dynamic pattern: an initial strain-induced stage, a strain accumulation propagation stage, and a residual strain stabilization stage and the displacement is characterized by an initial phase of concentration followed by gradual expansion. This study not only deepens the understanding of methane-air premixed gas explosion and its interaction with the roadway’s surrounding rock, but also provides an important scientific basis and technical support for coal mine safety production. Full article

In many scientific and engineering fields, such as hydrogeology, petroleum engineering, geotechnical research, and developing renewable energy solutions, fluid flow modeling in porous media is essential. In these areas, optimizing extraction techniques, forecasting environmental effects, and guaranteeing structural safety all depend on an understanding of the behavior of single-phase flows—fluids passing through connected pore spaces in rocks or soils. Darcy’s law, which results in an elliptic partial differential equation controlling the pressure field, is usually the mathematical basis for such modeling. Analytical solutions to these partial differential equations are seldom accessible due to the complexity and variability in natural porous formations, which makes the employment of numerical techniques necessary. To approximate subsurface flow solutions, traditional methods like the finite difference method, two-point flux approximation, and multi-point flux approximation have been employed extensively. Accuracy, stability, and computing economy are trade-offs for each, though. Deep learning techniques, in particular convolutional neural networks, physics-informed neural networks, and neural operators such as the Fourier neural operator, have become strong substitutes or enhancers of conventional solvers in recent years. These models have the potential to generalize across various permeability configurations and greatly speed up simulations. The purpose of this study is to examine and contrast the mentioned deep learning and numerical approaches to the problem of pressure distribution in single-phase Darcy flow, considering a 2D domain with mixed boundary conditions, localized sources, and sinks, and both homogeneous and heterogeneous permeability fields. The result of this study shows that the two-point flux approximation method is one of the best regarding computational speed and accuracy and the Fourier neural operator has potential to speed up more accurate methods like multi-point flux approximation. Different permeability field types only impacted each methods’ accuracy while computational time remained unchanged. This work aims to illustrate the advantages and disadvantages of each method and support the continuous development of effective solutions for porous medium flow problems by assessing solution accuracy and computing performance over a range of permeability situations. Full article

A multiphase model of hydrothermal liquefaction (HTL) using the computational fluid dynamics coupling discrete element method (CFD-DEM) is used to simulate biocrude oil production from sludge flocs in a continuous stirred tank reactor (CSTR). Additionally, the influence of the agitator speed and the slurry flow rate on dynamic biocrude oil production is investigated through full transient CFD analysis in a scaled-up CSTR study. The kinetics of the HTL mechanism as a function of temperature, pressure, and residence time distribution were employed in the model through a user-defined function (UDF). The multiphysics simulation of the HTL process in a stirred tank reactor using the Lagrangian–Eulerian (LE) approach, along with a standard k-ε turbulence model, integrated HTL kinetics. The simulation accounts for particle–fluid interactions by coupling CFD-derived hydrodynamic fields with discrete particle motion, enabling prediction of individual particle trajectories based on drag, buoyancy, and interphase momentum exchange. The three-phase flow using a compressible non-ideal gas model and multiphase interaction as design requirements increased process efficiency in high-pressure and high-temperature model conditions. Full article

Fluid inclusions, ubiquitously present within fluorite during diagenesis and mineralization, are released as inevitable ionic components in the pulp during mineral crushing and grinding. This study, grounded in geochemistry, combined microstructural analysis, spectroscopy, and X-ray computed tomography (X-CT) to investigate the morphology and petrographic characteristics of fluid inclusions in fluorite minerals. Building on this foundation, inductively coupled plasma optical emission spectrometry (ICP-OES) and ion chromatography (IC) were employed to analyze the release patterns of fluid inclusion components and their impact on fluorite flotation. The results reveal that fluid inclusions within fluorite are predominantly liquid-rich, two-phase (vapor-liquid) inclusions, exhibiting a spatial distribution density as high as 14.1%. Furthermore, fluid components are released during fluorite grinding, particularly homonymous Ca²⁺ ions, which significantly influence fluorite flotation behavior. Low concentrations of Ca²⁺ can activate fluorite flotation, whereas high concentrations of Ca²⁺ consume the collector (sodium oleate) in solution through competitive adsorption. This competition inhibits the adsorption of sodium oleate onto the fluorite mineral surface. The findings of this research provide theoretical support for in-depth studies on fluid inclusions in minerals and their effects on mineral flotation behavior, thereby facilitating the clean and efficient recovery of strategic fluorite mineral resources. Full article

Numerical simulation has played a crucial role in modeling the behavior of natural gas hydrate (NGH). However, the existing numerical simulators worldwide have exhibited limitations in functionality, convergence, and computational efficiency. In this study, we present a novel numerical simulator, GPSFlow/Hydrate, for modeling the behavior of hydrate-bearing geologic systems and for addressing the limitations in the existing simulators. It is capable of simulating multiphase and multicomponent flow in hydrate-bearing subsurface reservoirs under ambient conditions. The simulator incorporates multiple mass components, various phases, as well as heat transfer, and sand is treated as an independent non-Newtonian flow and modeled as a Bingham fluid. The CH₄ or binary/ternary gas hydrate dissociation or formation, phase changes, and corresponding thermal effects are fully accounted for, as well as various hydrate formation and dissociation mechanisms, such as depressurization, thermal stimulation, and sand flow behavior. In terms of computation, the simulator utilizes a domain decomposition technology to achieve hybrid parallel computing through the use of distributed memory and shared memory. The verification of the GPSFlow/Hydrate simulator are evaluated through two 1D simulation cases, a sand flow simulation case, and five 3D gas production cases. A comparison of the 1D cases with various numerical simulators demonstrated the reliability of GPSFlow/Hydrate, while its application in modeling the sand flow further highlighted its capability to address the challenges of gas hydrate exploitation and its potential for broader practical use. Several successful 3D gas hydrate reservoir simulation cases, based on parameters from the Shenhu region of the South China Sea, revealed the correlation of initial hydrate saturation and reservoir condition with hydrate decomposition and gas production performance. Furthermore, multithread parallel computing achieved a 2–4-fold increase in efficiency over single-thread approaches, ensuring accurate solutions for complex physical processes and large-scale grids. Overall, the development of GPSFlow/Hydrate constitutes a significant scientific contribution to understanding gas hydrate formation and decomposition mechanisms, as well as to advancing multicomponent flow migration modeling and gas hydrate resource development. Full article

Soy protein isolate (SPI) microgels were produced via heat-set gelation (4, 6, 8, and 10% by mass) followed by ultrasonication (400 W, 70% amplitude, 3 or 6 min) and used as stabilizers of oil–water emulsions (10% oil phase). The SPI concentration and ultrasonication time affected microgel size (236–356 nm) and polydispersity (0.253–0.550). The physical stability of the emulsions stabilized with 6 and 8% SPI microgels (6 min of ultrasonication) was evaluated for 14 d, influencing on the average size, creaming index and instability index of the emulsions, where those with 6% SPI microgels resulted in a major stability. The emulsions produced with these microgels encapsulated beta-carotene and were incorporated into whole yogurt at three concentrations: 5 (YE5), 10 (YE10), and 15% (YE15). The addition of the emulsions did not affect the physicochemical or microbiological quality of the yogurt. Rheological tests revealed that the yogurt behaved as a non-Newtonian and pseudoplastic fluid, with yogurts with more emulsions being less viscous. Sensory evaluation revealed consumer acceptance regarding color and texture; however, the perception of residual flavor was proportional to the amount of emulsion added. SPI microgels are effective stabilizers for β-carotene-loaded emulsions and a promising strategy for this compound delivery in yogurt. Full article