Fraction Profiles Research Articles

Darcy-Forchheimer Flow of Hybrid Carbon Nanotube over a Permeable Stretching/Shrinking Curved Surface

The Darcy-Forchheimer flow of hybrid carbon nanotube over a permeable curved stretching/shrinking surface is investigated in this work. The Darcy-Forchheimer phrase is used to describe porous spaces with different porosity and permeability. The current problem is modelled using curvilinear coordinates due to the curved form of the geometry. A similarity transformation will be applied to the partial differential equations (PDEs) of the fluid flow to convert them to ordinary differential equations (ODEs). The numerical solutions of the equations of continuity, momentum, and energy are obtained using the bvp4c solver in MATLAB. To examine the impact of various physical parameters, including nanoparticle volume fraction, suction, inertia coefficient, and porosity, on temperature and velocity profiles, as well as the local Nusselt number and skin friction, a comprehensive graphical analysis is conducted. By carefully modifying these parameters and scrutinizing their effects on the flow and heat transfer properties, a dual solution was observed on the graphs. The results suggest that increasing the single-wall carbon nanotube (SWCNT) nanoparticle and inertia coefficient parameters narrow the range of solutions. When the SWCNT of a shrinking curved sheet is raised, the skin friction increases. Meanwhile, the inertia coefficient showed the opposite pattern. The increased SWCNT and inertia coefficient parameters decrease the local Nusselt number. Moreover, the findings are compared and rigorously confirmed with previous reported findings in the literature.

Dilatancy and its coupling to the kinematics in sheared granular media

Models for slow flow of dense granular materials often treat the medium as incompressible, thereby neglecting the role of Reynolds dilatancy. However, recent particle simulations have demonstrated the presence of a significant coupling between the volume fraction and velocity fields. The model of Dsouza & Nott (J. Fluid Mech., vol. 888, 2020, R3) incorporates dilatancy and captures the coupling, but it has thus far lacked experimental validation. In this paper, we provide the first experimental demonstration of dilatancy and its coupling to the kinematics in a two-dimensional cylindrical Couette cell. We find a shear layer near the inner cylinder within which there is significant dilation. Within the shear layer, the azimuthal velocity decays roughly exponentially and the volume fraction rises with radial distance from the inner cylinder. The predictions of the model of Dsouza & Nott (2020) are in good agreement with the experimental data for a variety of roughness features of the outer cylinder. Moreover, by comparing the steady states resulting from different initial volume fraction profiles (but having the same average), we show the inter-dependence of the velocity and volume fraction fields, as predicted by the model. Our results establish the importance of shear dilatancy even in systems of constant volume.

Effect of bovine and buffalo ghee fractionation on triacylglycerols profile, lipids nutritional quality indices, thermal behavior, and tocopherols content: A comparative analysis with two categories of infant formula fat.

The increased use of dairy fat in various applications is facilitated by its fractionation into hard and liquid fractions. Herein, the fractionation of bovine ghee and buffalo ghee was investigated, and triacylglycerol (TAG) profiles of milk fat fractions and 2 categories of infant formulas fat were quantified by using ultra-performance convergence chromatography quadrupole time-of-flight mass spectrometry (UPC2-Q-TOF-MS) using carbon dioxide as the mobile phase. Furthermore, the thermal behavior of the different samples was evaluated, and tocopherols content was also quantified. A total of 176, 188, and 84 TAG species were identified in bovine ghee fractions, buffalo ghee fractions, and infant formulas fat, respectively. The results showed significant differences in TAG profile, lipid quality indices, and tocopherols content between the different fat types. Stearin fractions had higher levels of saturated TAG, while olein fractions had significantly lower levels. These results could provide interesting insights into the field of human milk fat substitutes.

Oxidative Gaseous Air Pollutant Exposure Interacts with PNPLA3-I148M Genotype to Influence Liver Fat Fraction and Multi-Omics Profiles in Young Adults.

PNPLA3-I148M genotype is the strongest predictive single-nucleotide polymorphism for liver fat. We examine whether PNPLA3-I148M modifies associations between oxidative gaseous air pollutant exposure (Oxwt) with i) liver fat and ii) multi-omics profiles of miRNAs and metabolites linked to liver fat. Participants were 69 young adults (17-22 years) from the Meta-AIR cohort. Prior-month residential Oxwt exposure (redox-weighted oxidative capacity of nitrogen dioxide and ozone) was spatially interpolated from monitoring stations via inverse-distance-squared weighting. Liver fat fraction was assessed by MRI. Serum miRNAs and metabolites were assayed via NanoString nCounter and LC-HRMS, respectively. Multi-omics factor analysis (MOFA) was used to identify latent factors with shared variance across omics layers. Multivariable linear regression models adjusted for age, sex, body mass index, and genotype with liver fat or MOFA factors as an outcome and examined PNPLA3 (rs738409; CC/CG vs. GG) as a multiplicative interaction term. Overall, a standard deviation difference in Oxwt exposure was associated with 8.9% relative increase in liver fat (p=0.04) and this relationship differed by PNPLA3 genotype (p-value for interaction term: pintx<0.001), whereby relative increases in liver fat for GG and CC/CG participants were 71.8% and 2.4%, respectively. There was no main effect of Oxwt on MOFA Factor 1 expression (p=0.85), but there was an interaction with PNPLA3 genotype (pintx=0.01), whereby marginal slopes were 0.211 and -0.017 for GG and CC/CG participants, respectively. MOFA Factor 1 in turn was associated with liver fat (p=0.006). MOFA Factor 1 miRNAs targeted genes in Fatty Acid Biosynthesis and Metabolism and Lysine Degradation pathways. MOFA Factor 9 was also associated with liver fat and was comprised of branched-chain keto acid and amino acid metabolites. The effects of Oxwt exposure on liver fat is exacerbated in young adults with two PNPLA3 risk alleles, potentially through differential effects on miRNA and/or metabolite profiles.

Two-phase flow evolution and interfacial area transport downstream of the mixing-vane spacer grid in rod bundle channels

This study investigated the axial two-phase flow evolution and interfacial area transport characteristics downstream of the mixing vane spacer grid (MVSG) in a tight lattice rod bundle channel with a subchannel hydraulic diameter of Dh = 17.27 mm. The experiment was conducted under the air-water two-phase flow at room temperature and atmospheric pressure. The phase distributions of 6 positions downstream of MVSG (Z/Dh = 9.15, 14.94, 20.73, 26.52, 32.31, and 61.26) were measured utilizing a self-developed double-layer wire-mesh sensor (WMS). 42 cases were obtained, involving the bubbly flow, cap-bubbly flow, and slug flow. Void fraction, bubble velocity, interfacial area concentration (IAC), and bubble size distribution (BSD) databases were built. Under the group-1 (G-1) flow, due to the swirling flow generated by MVSG, the G-1 bubbles were drawn from the bundle surface and the gap region into the subchannel center to form a spindle core-peak distribution. BSD results demonstrate that the swirling flow promotes bubbles’ coalescence. The one-dimensional (1-D) void fraction and IAC downstream of the MVSG decrease first and then recover, which contrasts with the non-mixing vane spacer grid (N-MVSG) effect. It was attributed to the increment of the bubbles’ velocity after MVSG due to the bubbles’ migration to the channel center and coalescence. Under the group-2 (G-2) flow, MVSG intensifies the core peak distribution of void fraction, and the void fraction profile is also spindle-shaped. The obvious bubbles’ break-up occurs at Z/Dh = 14.94 attributed to the swirling decay. The 1-D void fraction and IAC transport indicate, that with the liquid-velocity increment, the MVSG effect is different from the N-MVSG effect, which is mainly achieved by affecting the G-1 bubbles’ dynamic behaviors. The model evaluation utilizing the interfacial area transport equation (IATE) closing bubble interaction source/sink terms indicates that the advection effect dominates the IAC evolution and the contribution of the pressure effect is weak. The remarkable bubbles’ coalescence occurs under the high liquid velocity. In future studies, the additional bubble break-up and coalescence source/sink term model considering the MVSG effect should be developed based on these cases to improve the IATE prediction ability.

A Data Assimilation-Based Method for Real-Time Monitoring and Estimation of Gas Influx Size and Distribution During Gas Migration in a Marine Drilling Riser

Effective well control is essential in marine drilling operations to prevent catastrophic blowouts that endanger human lives and cause severe environmental damage, including long-lasting impacts on marine ecosystems. Accurate real-time monitoring and management of well conditions after taking gas influxes are critical for maintaining safety and environmental protection during offshore drilling operations.When a gas influx becomes trapped in a closed marine drilling riser, its upward migration can result in excessively high surface pressure, presenting significant risks to offshore drilling and well control. Therefore, the accurate estimation of downhole gas influx size and distribution during gas migration events is crucial for effectively managing these situations. The complexities of wellbore two-phase flow and gas migration make direct measurements challenging, leading to potential inaccuracies in traditional modeling approaches. This study introduces a Data Assimilation (DA) technique, employing the Ensemble Kalman Filter (EnKF), to improve the real-time estimation of gas influx rates and distribution, thereby enhancing the accuracy of two-phase flow models in marine drilling.This research utilizes full-scale gas influx migration experiments conducted at Louisiana State University, where gas was injected from the bottom of an experimental well to simulate a riser gas event in a Water-based Mud (WBM) system. Key real-time measurements, including downhole pressure gauges at multiple depths and Distributed Acoustic Sensing (DAS) data, were employed to validate the estimated gas influx size and distribution within the riser using the EnKF. The overall gas influx distribution was captured through the real-time estimation of a dimensionless distribution index (DI), offering additional insights into the spatial characteristics of the migrating gas. Additionally, a Drift Flux Model (DFM) calibrated online through DA was used to predict flow parameters such as gas void fraction profiles within the riser during migration. The validation of these predictions demonstrated a strong correlation between the estimated and measured values.The outcomes of this study underscore the effectiveness of the proposed method in estimating parameters that are otherwise difficult to measure directly, thereby improving the predictive accuracy of gas influx behavior in marine drilling risers. This method offers significant practical value by enhancing real-time decision-making and risk management in marine drilling operations that involve gas migration, contributing to the broader goals of offshore drilling safety and marine environment protection.

Statistical analysis and numerical simulation of wire coating process with sisko nanofluid: exploring variable thermophysical properties

The wire coating process enhances wire durability, safety, and performance, preventing corrosion and providing insulation against abrasion, temperature changes, and chemicals. To evaluate process quality, characteristics like fluid flow and heat transfer in the die are analysed. This work focuses on understanding molten polymer rheology via momentum, thermal distribution, and nanoparticle volume fraction profiles. A mathematical model is developed for a Sisko fluid using the Buongiorno model, which includes temperature-dependent thermophysical properties. The governing equation is reduced to dimensionless form using non-dimensional parameters and solved using the numerical technique. The results are visualised graphically for the parameters like Sisko fluid parameter, viscosity parameter (between 0 and 1), Brinkmann number, Hartmann number (between 2 and 10) using 2D and 3D plots. The study shows that the thermal field is enhanced by nanofluid factors, which subsequently enhances the heat transfer rate in the presence of nanoparticles. The optimization of the responses: shear stress rate ( S rz ) and rate of heat transfer ( Nur ) is carried out concurrently using the Surface Response Method. Furthermore, a sensitivity analysis has been conducted. The findings indicate that the viscosity parameter significantly impacts the sensitivity of the both shear stress rate and heat transfer rate.

Numerical treatments for peristaltic transport of Johnson‐Segalman nanofluid through a vertical divergence irregular channel in the presence of inclined magnetic field and double‐diffusive

AbstractThis paper presents a computational study for the peristaltic pumping within vertical irregular divergence channels filled with magnetic Johnson—Segalman nanofluid. Various configurations of the outer boundaries are considered, namely, square wave, multi‐sinusoidal wave, trapezoidal wave, and triangular wave. An inclined magnetic field together with nanoparticles and mass concentrations is considered. Influences of the Dufour and Soret numbers are examined, and the cases of low Reynolds number and long wavelength are applied. All the computations are obtained numerically using Mathematica symbolical software (ND‐Solve), and the obtained results are presented in terms of the axial velocity , heat transfer rate , nanoparticle fraction profile , concentration profile , temperature profile , extra stress tensor , pressure gradient , pressure rise , and stream function . The major outcomes revealed that the square wave shape gives higher pressure gradients near the inlet and outlet parts while the multi‐sinusoidal wave gives periodic behaviors of . Also, the maximizing in thermophoresis parameter is better to obtain a higher rate of heat transfer while the increase in thermo‐diffusion and diffusion thermo effects causes a reduction in the rate of heat transfer. The discipline of biological and medical engineering, particularly for nanofluid peristaltic pumps, can benefit from the practical uses of such a model, which can be used to simulate the small vessel transport of particles in hemodynamics.

A three-axis regime diagram for quantitative analyses of the mixing field structure in laminar and turbulent combustion

The combustion characteristics and stability are affected primarily by the mixing field structure. The goal of many practical systems is to achieve higher stability by creating Inhomogeneous, Partially Premixed, and Stratified (IPPS) environments. A three-axis regime diagram is proposed in this work to describe the mixing field structure of the IPPS, the non-premixed, and the premixed environments. The proposed axes of the diagram are the mean, the fluctuations, and the 2-D gradients of the conserved scalar mixture fraction.Highly resolved two-dimensional measurements of the mixture fraction in highly stabilized burners with well-controlled mixture inhomogeneity using advanced Rayleigh scattering measurements are used in this study to investigate the abilities of the proposed diagram. The effects of the mixing level, equivalence ratio, and Reynolds number on the mixing field structure were investigated using this diagram adequately. The three-axis diagram provided quantitative detailed information on the mixing field structure at different operating conditions. In addition, the local mixing layer thickness data are extracted from the diagram based on the mixture fraction profiles and the corresponding mixture fraction gradients profiles in the mixture fraction space.The level of mixture inhomogeneity and equivalence ratio significantly affect the mixing field structure, while the effect of the Reynolds number in turbulent conditions is weak. The correlations between the local mixing layer thickness and the main operating parameters are observed using its PDFs. Reducing the level of mixture inhomogeneity reduces the maximum mixture fraction gradients at zero fluctuations of the mean mixture fraction. The correlations are clear for further analytical investigation. This study shows that the proposed three-axis diagram is a useful tool to investigate and analyze the mixing field structure of the IPPS regimes.

Oxygen Concentration and Reaction Rate Profiles Analysis of Polymer Electrolyte Fuel Cell

Introduction A one-dimensional (1D) model of polymer electrolyte fuel cells (PEFCs) is especially suitable for performance diagnostics, design optimization, and material evaluation, due to its high computational efficiency. Uniform distributions of reactants are commonly assumed in 1D models, i.e., a single representative reactant concentration inside the gas channel is required. However, this concentration is strongly dependent on the flow field. Although plenty of 1D models with sufficient accuracy as 3D models have been reported, the effects of the flow field have not been sufficiently discussed in the literature. In this work, efforts have been put into developing a generalized theory suitable for various flow fields to quantitatively analyze the in-plane reaction rate profile, so that the flow-field-sensitive representative reactant concentration can be employed to further fill the gaps in the 1D models. Analytical model A series of a plug flow reactor (PFR) and a continuous stirred tank reactor (CSTR) was proposed to explain the unideal flow and the macromixing behaviors inside a gas channel coupled with a gas diffusion layer (GDL), as shown in Fig. 1(a).[1] The fraction of PFR’s space time to total space time was defined as the characterization factor γ, which should be the function of flow field shape and flow rate. Furthermore, under-rib oxygen concentration and current density profiles were taken into account by introducing the dimensionless moduli.[2] Especially, the under-rib convection can be evaluated by Péclet modulus Pe, by increasing which will improve the under-rib mass transfer and the effectiveness factor f. The in-plane profile of the ohmic resistance of the membrane was assumed uniform. The oxygen reduction reaction (ORR) was regarded as a surface reaction occurring on the interface of cathode catalyst layer (CCL) and GDL. The ORR rate was assumed to be proportional to oxygen partial pressure and independent of relative humidity (RH). Results and Discussion The characterization factors γ of different flow fields were determined according to the residence time distribution simulated by the computational fluid dynamics (CFD) model. The ORR rate constant at each electrical potential was obtained from the measured polarization curve of a parallel gas channel (PN0) with 0.35 mm channel depth, by employing the analytical model mentioned above. Fig. 1(c) shows the polarization curves of parallel channels with staggered 1-mm-long partially narrowed structures (PSN1) and PN0 with different channel depths. Compared to the PN0, the under-rib convection improves the oxygen mass transport and the cell performance, where f increases 17 % at 0.35 V in the case of the PSN1. On the other hand, increasing the channel depth restrains the oxygen diffusion and f decreases by 18 % at 0.35 V. The analytical model results show good agreement with experiment data, which indicates that the effects of the flow field can be summarized by the parameters γ and f.The analytical model provides the in-plane oxygen mole fraction and current density profiles. Fig. 2 shows the oxygen partial pressure distribution in a single gas channel calculated by the CFD model and analytical model. The mean oxygen partial pressure on the under-channel CCL-GDL interface calculated by the analytical model approximately equals the CFD result. By employing the ohmic resistance estimated according to the inlet conditions, although the current density is underestimated where RH is high, the integral mean of the in-plane current density offered by the analytical model has less than 5 % error compared to the CFD results, as shown in Fig. 3.The analytical model also gives an effective way to estimate the integral mean in-plane oxygen partial pressure. Fig. 4 demonstrates the relationships among integral mean, inlet, and outlet oxygen partial pressures. When the reaction rate constant and effectiveness factor are fixed, Fig. 4 also reveals the relationships between total and local current densities. If the parameters γ and f are determined, the integral mean of the oxygen partial pressure can be obtained when the outlet oxygen partial pressure or oxygen conversion is known. Conclusions The analytical model quantitatively demonstrates the effects of the flow field shape and provides a quick and effective way to estimate the reaction rate profile, based on the fixed in-plane ohmic resistance assumption. This model was verified by experiment and CFD model in case of the oxygen conversion less than 0.33 and can be applied to ORR kinetics determination and rapid performance prediction. Reference [1] Y. Ma et al., J. Electrochem. Soc., 170, 084506 (2023).[2] Y. Ma et al., ECS Meet. Abstr., MA2023-02, 1867 (2023). Figure 1

A three-phase dispersion profile model for stratified pipe flow: Effects of gas bubbles on the distribution of oil and water droplets

A three-phase dispersion profile model for stratified gas/oil/water pipe flow was developed. The main goal was to incorporate the effects of gas bubbles on the cross-sectional distribution of oil and water droplets in the continuous liquids. Gas bubbles entrain from the gas layer above the oil/water layers and modify the oil and water dispersion profiles in several different ways. Increased hindered settling due to gas bubbles, reduction of the effective background mixing density that affects buoyancy, turbulence suppression due to droplets and bubbles and finally reduction of oil and water droplet entrainment rate due to area blocking by gas bubbles at the oil/water interface. All three dispersion profiles were modelled consistently with respect to their mutual coupling. The tuned model qualitatively reproduced the shapes and magnitude of the volume fraction profile data obtained from X-ray measurements. Several areas were identified where more fundamental experimental research would be needed.

Elucidating high-pressure chemistry in acetylene oxidation: Jet-stirred reactor experiments, pressure effects, and kinetic interpretation

Acetylene plays a crucial role as an intermediate in the combustion of complex hydrocarbons, such as, e.g., jet fuels. In this study, high-pressure acetylene oxidation has been investigated by a combination of kinetic and experimental methods using a jet-stirred reactor (JSR) in the range of 497–910 K at p = 24 atm. The study covered three fuel-equivalence ratios: φ = 0.5 (fuel-lean), φ = 1.0 (stoichiometric), and φ = 3.0 (fuel-rich). Mole fraction profiles of 10 species, including CO, CO2, CH4, C2H4, C2H6, C3H6, C3H8, CH3OH, CH3CHO, and C3H4O, were identified and quantified using gas chromatography (GC) and gas chromatography-mass spectrometry (GC–MS). A kinetic model for describing the high-pressure chemistry of acetylene oxidation is proposed, which well characterizes important experimental findings, such as the fuel oxidation reactivity and the speciation of crucial products. At high pressures (p = 24 atm), acetylene exhibits a higher fuel consumption than at lower pressures (p = 1 and 12 atm) because of the increased sensitivity of dehydrogenation reactions by OH radicals accelerating the oxidation of the fuel at low temperatures. Furthermore, fuel-specific intermediates are observed, including acetaldehyde, propanal, small alkanes, and alkenes. These species mainly result from H-abstraction reactions by OH following O2-addition reactions from triple carbon bond moieties in acetylene. The formation of further products, such as carbon monoxide and carbon dioxide, is closely related to the consumption of these fuel-specific species. In particular, the formation of aromatics, such as e.g., benzene and toluene, are detected at trace levels in the current experiments due to the rapid formation and decomposition process occurring at high pressures. By analyzing the distinct kinetic behavior, it was found that acetylene was almost completely depleted at higher system pressure (p = 24 atm). Some intermediates are rather active and can react with O2 and peroxides. Consequently, the high-pressure oxidation of acetylene mainly proceeds along the pathway of CC → CHCHOH → HOCHO/OCHCHO → CO → CO2 at the high-pressure chemistry (p = 24 atm). Overall, this study provides valuable insights into the pressure-dependent combustion behavior of acetylene and its implications for optimizing jet fuel combustion processes.

Brownian dynamics simulation of the structural evolution in monodisperse hard-sphere suspensions during drying and sedimentation processes.

The drying behavior of monodisperse colloidal films, with a focus on the influence of process variables on film microstructures, is explored via Brownian dynamics (BD) simulations. In our model, hard-sphere colloidal particles are dispersed in a Newtonian liquid with an initial particle volume fraction of 0.1. The effects of the drying rate and sedimentation on the evolving microstructures are systematically investigated using two dimensionless numbers: the Péclet number (Pe), which represents the competition between evaporation and diffusion, and the sedimentation number (Ns), which reflects the relative influence of sedimentation on evaporation. First, we analyze the local particle volume fraction and film structure at various Pe and Ns. As Pe increases, particle accumulation occurs near the liquid-gas interface, whereas a high Ns promotes dense packing near the substrate owing to sedimentation. The BD simulation results, viz. the local volume fraction profiles and drying regime maps, are in good agreement with those of the continuum model proposed by Wang and Brady. Structural analysis of the dried films reveals that at a low Pe (Pe = 0.1), a face-centered cubic (FCC) structure dominates, primarily independent of the sedimentation effects. In contrast, a high Pe leads to hexagonal close-packed or amorphous structure formation. Notably, at intermediate drying rates (Pe = 10), an increase in Ns promotes additional FCC ordering in the final film structure. Our study provides new insights into the hitherto underexplored role of sedimentation in the structural evolution of drying colloidal films, revealing the mechanisms of drying-induced assembly in colloidal systems.

Metabolite Profiling of Potential Fraction from Ethyl Acetate Extract of Ziziphus mauritiana Leaves by LC-MS/MS Analysis

Metabolite Profiling of Potential Fraction from Ethyl Acetate Extract of Ziziphus mauritiana Leaves by LC-MS/MS Analysis

Integrative Proteomic and Phosphoproteomic Profiling Reveals the Salt-Responsive Mechanisms in Two Rice Varieties (Oryza Sativa subsp. Japonica and Indica).

Salinity stress induces ionic and osmotic imbalances in rice plants that in turn negatively affect the photosynthesis rate, resulting in growth retardation and yield penalty. Efforts have, therefore, been carried out to understand the mechanism of salt tolerance, however, the complexity of biological processes at proteome levels remains a major challenge. Here, we performed a comparative proteome and phosphoproteome profiling of microsome enriched fractions of salt-tolerant (cv. IR73; indica) and salt-susceptible (cv. Dongjin/DJ; japonica) rice varieties. This approach led to the identification of 5856 proteins, of which 473 and 484 proteins showed differential modulation between DJ and IR73 sample sets, respectively. The phosphoproteome analysis led to the identification of a total of 10,873 phosphopeptides of which 2929 and 3049 phosphopeptides showed significant differences in DJ and IR73 sample sets, respectively. The integration of proteome and phosphoproteome data showed activation of ABA and Ca2+ signaling components exclusively in the salt-tolerant variety IR73 in response to salinity stress. Taken together, our results highlight the changes at proteome and phosphoproteome levels and provide a mechanistic understanding of salinity stress tolerance in rice.

CFD Modeling of Film Condensation from a Steam-Air Mixture in Vertical Channels

Steam condensation in the presence of a noncondensable gas is of vital importance for passive cooling containment systems. The noncondensable gas causes a significant reduction in the condensation rate and heat transfer across the containment, which is important for postulated loss-of-coolant accidents in a nuclear reactor. In this work, computational fluid dynamics models of condensation and the adjacent single-phase steam-air mixture flow are developed for laminar and turbulent flow in vertical channels by two distinct wall condensation modeling approaches using the commercial code STAR-CCM+. The first is the fluid film model available in STAR-CCM+, which solves liquid layer governing equations with connections to the adjacent gas mixture flow. The second is a user-defined wall condensation model that neglects the fluid film and instead accounts for mass, momentum, and heat transfer via user-defined volumetric sink terms adjacent to the cold wall. The condensation models are assessed by first comparing the calculated results with the numerical solution of laminar flow, solved using a complete two-phase model that solves parabolic equations based on conservation of mass, momentum, energy, and species for each phase. Next, the results of a two-dimensional analysis are compared with COPAIN experiments and existing numerical solutions from three-dimensional analyses. The comparisons include new, detailed results that have not been reported in previous analyses of a COPAIN case. These new results include local field profiles of velocity, temperature, and air mass fraction, and local mass flux.

A novel 4-aminoquinoline chemotype with multistage antimalarial activity and lack of cross-resistance with PfCRT and PfMDR1 mutants.

Artemisinin-based combination therapy (ACT) is the mainstay of effective treatment of Plasmodium falciparum malaria. However, the long-term utility of ACTs is imperiled by widespread partial artemisinin resistance in Southeast Asia and its recent emergence in parts of East Africa. This underscores the need to identify chemotypes with new modes of action (MoAs) to circumvent resistance to ACTs. In this study, we characterized the asexual blood stage antiplasmodial activity and resistance mechanisms of LDT-623, a 4-aminoquinoline (4-AQ). We also detected LDT-623 activity against multiple stages (liver schizonts, stage IV-V gametocytes, and ookinetes) of Plasmodium's life cycle, a feature unlike other 4-AQs such as chloroquine (CQ) and piperaquine (PPQ). Using heme fractionation profiling and drug uptake studies in PfCRT-containing proteoliposomes, we observed inhibition of hemozoin formation and PfCRT-mediated transport, which constitute characteristic features of 4-AQs' MoA. We also found minimal cross-resistance to LDT-623 in a panel of mutant pfcrt or pfmdr1 lines, but not the PfCRT F145I mutant that is highly resistant to PPQ resistance yet is very unfit. No P. falciparum parasites were recovered in an in vitro resistance selection study, suggesting a high barrier for resistance to emerge. Finally, a competitive growth assay comprising >50 barcoded parasite lines with mutated resistance mediators or major drug targets found no evidence of cross-resistance. Our findings support further exploration of this promising 4-AQ.

Void drift in narrow rectangular channels for highly advective bubbly flows: A macroscopic drift-flux model derived from two-fluid local simulations

This article addresses the issue of reduced models to describe turbulent two-phase flows in industrial applications. This work is an application based on Bois (2021) theoretical derivations to connect the spatially-averaged drift-flux model (DFM) to the local Reynolds-averaged two-fluid model (TFM). It presents new opportunities to calibrate closure laws or propose new models based on finer-scale descriptions. Highly convective steady bubbly flows with wall-peaking void fraction profiles are considered. Dispersed bubbles are weakly deformable. A new model dedicated to void fraction dispersion in flat rectangular channels is developed for application into the DFM. The model is calibrated based on reference local Euler–Euler two-fluid simulations of pressurised water and steam mono-dispersed bubbles, in adiabatic conditions. 64 conditions are considered to cover regularly the 3D parameter space in void fraction, Reynolds and Eötvös numbers. The new formulation proposed shows a very good fit with the post-processed predictions of local CFD simulations along with a substantial reduction in grid requirement. The model contains sub-filter correlations between vapour concentration and mixture or relative velocities. This model derived from local simulations is validated a posteriori in an industrial component scale code where the full space-filtered DFM is implemented and resolved. This work proves the benefits and feasibility of one-by-one model development and calibration based on two-fluid simulations.

Mass and momentum balance during particle migration in the pressure-driven flow of frictional non-Brownian suspensions

The transient shear-induced particle migration of frictional non-Brownian suspensions is studied using particle-resolved simulations. The numerical method – the fictitious domain method – is well suited to heterogeneous flows thanks to a frame-invariant formulation of the subgrid (lubrication) corrections that does not involve the ambient flow (Orsi et al., J. Comput. Phys., vol. 474, 2023, 111823). The paper aims to give an accurate quantitative picture of the mass and momentum balance during the flow. The various assumptions and local constitutive laws that together form the suspension balance model (SBM) are thoroughly examined. To this purpose, the various quantities of interest are locally averaged in space and time, and their profile across the channel is extensively studied, with specific attention to the time evolution of the different contributions, either hydrodynamic in nature or from contact interactions, to the shear and normal stresses. The latter, together with the velocity gradient in the wall-normal direction and the volume fraction profile, yield the local constitutive laws, which are compared with their counterpart obtained in homogeneous shear flow. A fair agreement is observed except in a layering area at the boundaries and at the very centre of the channel. In addition, the main assumption of the SBM, i.e. the local relation between the hydrodynamic force on the particles and the particle flux, is meticulously investigated. The hydrodynamic force is found to be mainly a drag, except in the lower range of the probed volume fractions, where a non-drag contribution is observed.

Phytochemical profiling from Dioscorea bulbifera L. bulbils using LC-MS, proximate analysis and antidiabetic activity: in vitro and in silico approaches

ABSTRACT The nutritional value and medicinal properties of highly edible Bulbils of Dioscorea bulbifera L are still unexplored. This study reported the nutritional and medicinal values by In vitro, and In silico studies along with chemical profiling using LC-MS. The proximate analysis was conducted by the AOAC method. The antioxidant and antidiabetic activities were assessed using DPPH and α- α-glucosidase enzyme inhibition assay. Molecular docking was used to do an In silico examination of the identified molecules, and ADMET analysis of the hit candidate was also performed. The result showed that bulbils of D. bulbifera were found to have a higher percentage of protein (8.83%), fat (0.96%), and fiber (5.40%). It exhibited significant levels of phenolic and flavonoid content 106.93 ± 0.02 mg GAE/g and 11.51 ± 0.02 mg QE/g, respectively. The ethyl acetate fraction of D. bulbifera showed potent antioxidants with an IC 50 = 13.75 ± 0.6 μg/mL. Furthermore, the methanol extract showed more than 50 % inhibition activity with IC 50 values of 26.29 ± 0.6 μg/mL and 191.2 ± 0.7 μg/mL against α-glucosidase and α-amylase, respectively. The ethyl acetate fraction showed higher α-glucosidase and α-amylase inhibitory activity with an IC 50 of 14.42 ± 0.4 μg/mL and 171.5 ± 0.4 μg/mL, respectively, compared to the standard acarbose (p < 0.05). Chemical profiling of most bio-active ethyl acetate fraction was done using LC-MS analysis, where eleven compounds were annotated. In conclusion, bulbils of D. bulbifera demonstrate promising anti-diabetic activity through In vitro and In silico studies.