Continuous Phase Research Articles

Marching exercise on balance and blood pressure among Thai community-dwelling older adults at risk of falling

Falls are a major cause of death among older people, and they are becoming a bigger problem as people lose their balance. A quasi-experimental study was conducted to examine the effects of marching exercises on the balance abilities of community-dwelling Thai seniors at risk of collapsing. Thirty-five participants were randomly assigned to the experimental or control group. The experimental group engaged in a 12-week marching exercise program that included a continuous foot-turning phase. The control group did not engage in any form of exercise. Compared to the control group, the experimental group demonstrated significant improvements in their ability to maintain their balance. The experimental group's timed up and go test (TUG) score decreased by 3.54 seconds,<em> </em>95%CI: (2.13 to 4.95), p<0.001 while the functional reach test (FRT) score increased by 4.80 centimeters, 95%CI: (2.34 to 7.25), p<0.001. The systolic blood pressure decreased by 8.62 mmHg, the diastolic blood pressure by 6.48 mmHg, and the heart rate by 4.04 beats per minute. These findings imply that regular marching exercise may improve balance in at-risk older adults. Further research is necessary to clarify the effects of marching exercise on people diagnosed with chronic diseases.

Polytypic metal chalcogenide nanocrystals.

By engineering chemically identical but structurally distinct materials into intricate and sophisticated polytypic nanostructures, which often surpass their pure phase objects and even produce novel physical and chemical properties, exciting applications in the fields of photovoltaics, electronics and photocatalysis can be achieved. In recent decades, various methods have been developed for synthesizing a library of polytypic nanocrystals encompassing IV, III-V and II-VI polytypic semiconductors. The exceptional performances of polytypic metal chalcogenide nanocrystals have been observed, making them highly promising candidates for applications in photonics and electronics. However, achieving high-precision control over the morphology, composition, crystal structure, size, homojunctions, and periodicity of polytypic metal chalcogenide nanostructures remains a significant synthetic challenge. This review article offers a comprehensive overview of recent progress in the synthesis and control of polytypic metal chalcogenide nanocrystals using colloidal synthetic strategies. Starting from a concise introduction on the crystal structures of metal chalcogenides, the subsequent discussion delves into the colloidal synthesis of polytypic metal chalcogenide nanocrystals, followed by an in-depth exploration of the key factors governing polytypic structure construction. Subsequently, we provide comprehensive insights into the physical properties of polytypic metal chalcogenide nanocrystals, which exhibit strong correlations with their applications. Thereafter, we emphasize the significance of polytypic nanostructures in various applications, such as photovoltaics, photocatalysis, transistors, thermoelectrics, stress sensors, and the electrocatalytic hydrogen evolution. Finally, we present a summary of the recent advancements in this research field and provide insightful perspectives on the forthcoming challenges, opportunities, and future research directions.

Solution Synthesis and Diffusion-Mediated Formation Pathway of NbTe4 Particles.

NbTe4 is an important material because of its fundamental low-temperature electronic behavior and its potential interest for thermoelectric, catalytic, and phase-change applications, especially as nano- and microscale particles. As a tellurium-rich group V transition metal telluride, bulk NbTe4 is typically synthesized through high-temperature solid-state or metal flux reactions and NbTe4 films can be made by sputtering and annealing, but NbTe4 is generally not amenable to the lower-temperature solution-based syntheses that yield small particles. Here, we demonstrate a solvothermal route to NbTe4 particles that is based on mainstream colloidal nanoparticle synthesis. We find that the reaction proceeds in situ through a multistep pathway that begins by first forming elemental tellurium needles. NbTe4 then deposits on the surface of the tellurium needles through a diffusion-based process. Time-point studies throughout the reaction reveal that crystallographic relationships between Te and NbTe4 define how the diffusion-based reaction proceeds and help to rationalize the morphology of the resulting NbTe4 particles. As synthesized, NbTe4 particles exhibit a surface consisting of predominantly Nb-Te and reduced NbOx species, but after storage, surface oxidation transforms these species to primarily Nb2O5 and TeO2, while the NbTe4 remains unchanged. These synthetic capabilities and reaction pathway insights for NbTe4, made using a solvothermal method, will help to advance future studies on the properties and applications of this and related tellurides.

Extensive study of droplet dynamics with end-grafted polymer chains in Pickering emulsions: Molecular Dynamics simulation and a generic model derived from the generalized Langevin equation

This paper investigates Pickering emulsions (PEs), formed by suspending oil droplets as the dispersed phase in water as the continuous phase using uncharged particles at their interface. To prevent coalescence, the particles are grafted with polymer chains, as emulsifier, not only to provide steric repulsion forces through the excluded volume between monomers floating in water, compensating for the absence of Coulombic repulsive forces but also control emulsion stabilization/destabilization. We combined molecular dynamics (MD) simulations and a generalized Langevin equation (GLE) model to study the dynamics of hairy-droplets using two dynamic quantities: mean square displacement (MSD) and velocity autocorrelation function (VACF). The number of grafted-polymer-chains, f, was the main parameter of interest, while the other parameters of the system were kept constant. A statistical approach was used to estimate theoretical GLE-based model parameters along with their uncertainties, providing insight into the diffusion behavior of these hairy-droplets and specifically addressing the transition between different observed regimes. we capture three specific values of grafted-polymer-chains as, fb=47 and ft=185 describe the transitions of mushroom-brush conformation of grafted-polymer-chains and viscous-viscoelastic behavior of hairy-droplets, respectively, and fg=257 representing the gel-like state number.

Full-space metasurfaces for independent manipulation of transmission and reflection.

In recent years, beam manipulation using metasurfaces has evolved from being limited to either a transmission or reflection space to encompassing a full space. However, existing methods still inevitably require complex systems and are unable to achieve continuous and arbitrary phase manipulation. Here, one type of a bilayer metasurface is proposed to simultaneously manipulate reflection and transmission phases continuously and independently, which also makes the optical system more compact without requiring any analyzers and enhances the degree of freedom for full-space beam manipulation. As a proof-of-concept demonstration, one device is designed to show different holograms in transmission and reflection spaces. Additionally, the Dammann grating designed in the reflection hologram increases the information capacity. The proposed method may pave the way toward achieving a variety of applications such as multi-channel beam manipulation and multifunctional optical devices.

Development of the full Lagrangian approach for modeling dilute dispersed media flows (a review)

Continuum models of media with zero pressure are widely used in various branches of physics and mechanics, including studies of a dilute dispersed phase in multiphase flows. In zero-pressure media, the particle trajectories may intersect, “folds” and “puckers” of the phase volume may arise, and “caustics” (the envelopes of particle trajectories) may appear, near which the density of the medium sharply increases. In recent decades, the phenomena of clustering and aerodynamic focusing of inertial admixture in gas and liquid flows have attracted increasing attention of researchers. This is due to the importance of taking into account the inhomogeneities in the impurity concentration when describing the transport of aerosol pollutants in the environment, the mechanisms of droplet growth in rain clouds, scattering of radiation by dispersed inclusions, initiation of detonation in two-phase mixtures, as well as when solving problems of two-phase aerodynamics, interpretation of measurements obtained by LDV or PIV methods, and in many other applications. These problems gave an impetus to a significant increase in the number of publications devoted to the processes of accumulation and clustering of inertial particles in gas and liquid flows. Within the framework of classical two-fluid models and standard Eulerian approaches assuming single-valuedness of continuum parameters of the media, it turns out impossible to describe zones of multi-valued velocity fields and density singularities in flows with crossing particle trajectories. One of the alternatives is the full Lagrangian approach proposed by the author earlier. In recent years, this approach has been further developed in combination with averaged Eulerian and Lagrangian (vortex-blob method) methods for describing the dynamics of the carrier phase. Such combined approaches made it possible to study the structure of local zones of accumulation of inertial particles in vortex, transient, and turbulent flows. This article describes the basic ideas of the full Lagrangian approach, provides examples of the most significant results which illustrate the unique capabilities of the method, and gives an overview of the main directions of further development of the method as applied to transient, vortex, and turbulent flows of “gas-particle” media. Some of the ideas discussed and the results presented below are of a more general interest, since they are also applicable to other models of zero-pressure media.

Co-regulation of gelatin content and Hofmeister effect on 3D-printed high internal phase emulsion gel characteristics for resveratrol delivery

The study investigated the influence of gelatin (GE) content and the Hofmeister effect on the physicochemical, rheological, and printing properties of high internal phase emulsion (HIPE) gels. Incremental GE content introduced more triple helix structures (junction zones) in the continuous phase of HIPE. By soaking in a sodium citrate (Na3Cit)-glycerol-water solution, polymer chain bundling, hydrophobic interactions, and abundant hydrogen bonds between GE and glycerol further increased, achieving a more compact crosslinking density and internal network. The optimized HIPE-GE-Cit3- gel with 1.5 wt% GE displayed improved shape retention, generating smoother and firmer gels with enhanced freezing and heat resistance. Its excellent mechanical strength and viscoelasticity can resist large deformations and maintain reversible structures. HIPE-GE gel with 1.5 wt% GE demonstrated satisfactory printing suitability with clear outlines, favorable visual aesthetics, and minimal dimensional deviation. This post-soaking (Hofmeister effect) also eliminated rough surfaces and visible layered lines, improved mechanical properties and more elastic networks. The printed HIPE-GE1.5-Cit3- gel with higher rigidity and elasticity impeding molecular release, protected encapsulated resveratrol against degradation, especially from heat, and enhanced the release rate in the small intestine, achieving sustained release. This work produced customizable HIPE gels by 3D printing with multiple advantages to develop personalized nutraceutical carriers with high-temperature tolerance.

Microstructural evolution and micromechanical properties of asphalt due to chloride salt erosion: Insights from atomic force microscopy

To explore the impact of chloride salt erosion on the microstructure and micromechanical properties of asphalt, this study utilizes the atomic force microscopy (AFM) to examine the evolution of micromorphology, surface roughness, adhesion, and Young’s modulus of asphalt in dry conditions, under various chloride salt concentrations, and after different erosion times. The results indicate significant changes in the microtopography of the asphalt surface due to chloride salt erosion, characterized by the reorganization of nanoscale protrusions and white spots. This results in a decrease in their quantity and total area, while the average area increased, demonstrating a trend of phase dispersion and aggregation. Erosion increased the surface roughness of the asphalt and significantly altered its mechanical properties. Specifically, with an increase in chloride salt concentration, the average roughness (Ra) of asphalt, after one day of erosion relative to its dry state, increased by 7.99 %, 33.06 %, and 52.55 %, respectively. As the erosion time was extended, at a 2.5 % chloride salt concentration, the growth rate of Ra reached 33.06 %, 54.68 %, and 67.22 %, respectively. A declining trend in nano adhesion was observed, indicating internal structural damage and reduced durability, while Young’s modulus significantly increased, suggesting a densification of the asphalt matrix and enhanced rigidity.

Insight into the aminosilane functionalized-montmorillonite/Pebax mixed matrix membranes with selectively fast gas transport channels for CO2 permeation

Mixed matrix membranes (MMMs) hold a great prospect for CO2 separation and capture. To further improve the separation efficiency, surface modification of fillers with organosilanes is an effective way to establish a link between polymers and fillers with respect to optimizing the interfacial morphology. In this study, MMMs were prepared using polyether-block-polyamide (Pebax) as a continuous matrix phase and aminosilane functionalized-montmorillonite (K-MMT) as dispersive fillers. K-MMT plays multiple roles for modifying the structure and improving the performance of resultant MMMs. The introduction of K-MMT disrupts the hydrogen bonding between the hard segments and decreases the crystallinity of MMMs. Furthermore, the inner channels of K-MMT could provide high-speed facilitated gas transport passages, of which the structural metal cations further offer transport carriers so as to substantially increase the CO2 permeability. Moreover, K-MMT can positively capture CO2 in gas mixture on the dependence of the mobility of long-chain amino groups and the reversible reaction between CO2 and amine groups. Additionally, the introduction of 3-aminopropyl triethoxysilane tends to enlarge the structural interlayer spacings of MMT, resulting into the facilitated penetration of CO2 through resultant MMMs. In brief, the MMMs doped with 4 % K-MMT show the optimal gas separation, i.e., CO2 permeability of 196.4 Barrer and CO2/N2 ideal selectivity of 162.4, which is far beyond the proposed 2019 upper bound for CO2/N2 system.

Scalable In-situ Microfibrillar dielectric films: Achieving exceptional energy density and efficiency

It is a formidable challenge to develop a feasible strategy for the scalable fabrication of all-organic dielectrics with simultaneous improvements in both discharged energy density (Ud) and efficiency (η). Herein, an innovative technology of “melting extrusion-hot stretching-quenching” was put forward for the large-scale preparation of all-organic polymer dielectric films, where polymethyl methacrylate (PMMA) was miscible with polyvinylidene fluoride (PVDF) to form single dispersed phase in the polypropylene (PP) matrix and in-situ transformed into microfibrils with the aid of elongational flow field. Thereby, a simultaneous enhancement in the dielectric constant and breakdown strength was achieved and the as-prepared PP-based all-polymer dielectric film exhibited an unprecedented ultrahigh Ud of 9.6 J cm−3 and an exceptional η of 90.9 %. Experimental verification and computational simulation confirmed that the formation of highly oriented PMMA/PVDF microfibrils and well-aligned interfaces are constructive to enhancing breakdown strength by suppressing electric field distortion. The highly oriented dipoles in PVDF and PMMA, coupled with the eliminated ferroelectric behavior of PVDF, synergistically contributed to the heightened Ud and η. The approach presented in this work opens up a promising avenue for the large-scale production of all-organic capacitor films with enhanced Ud and η, heralding a new era of advanced dielectric materials.

Droplet size, spray structure and droplet velocity mapping in hollow cone sprays using SLIPI-based techniques

The Structured Laser Illumination Planar Imaging (SLIPI) technique received significant attention in recent years due to notable improvements in the measurement of droplet size and the visualization of internal structure in both dilute and dense sprays. However, despite the improvements, the technique remains limited to these microscopic characteristics of the spray, primarily due to the complexity of the optical setup and image acquisition process. In this article, the capabilities of the SLIPI application are exploited, specifically employing the 3p-SLIPI-LIF/Mie (SLSD), and combined application of 1p-SLIPI-LIF & PIV (1p-SLIPI-PIV) for mapping of both Sauter Mean Diameter (SMD) and mean droplet velocity in combination with detailed spray structure analysis. The measurements were carried out in hollow cone sprays operated at the range of injection pressures from 25 to 107 bar. The results obtained using the SLIPI techniques were compared with the Phase Doppler Anemometry (PDA) measurements showing good agreement for both the SMD and mean droplet velocity. The significant improvements in the important microscopic characteristics (droplet size & velocity) and visualization of the internal structure in a wider flow field of hollow cone sprays allowed detailed analysis and understanding of the dispersed phase flow owing to the suppression of diffused light resulting from the multiple scattering effects.

A numerical investigation on the dynamics of particle deposition and fouling on a vertical falling film pipe

The zero liquid discharge process is designed to eliminate the discharge of industrial wastewater into the environment, addressing significant environmental concerns that have emerged in recent decades. Falling film evaporator is one of the primary technologies employed in these systems. As observed, there is a noticeable lack of research numerically simulating these phenomena in a vertical pipe including falling film flow. In the present study, an effort has been made to address the existing research gap by conducting numerical simulation of particles deposition and fouling phenomena in a falling film flow in a three-dimensional vertical pipe using computational fluid dynamics. Continuous phases which contain two non-penetrating fluids, i.e., air and water, are simulated using volume of fluid multiphase model and the large eddy simulation turbulence model. Meanwhile, particles motion has been tracked utilizing discrete phase model. Water film enters the pipe with a thickness of 3.7 mm and an inlet velocity of 1 m/s, and particles with a density of 3110 kg/m3 are injected through the water inlet surface in various cases, each with different diameters. As observed, with an increase in particles diameter from 5 to 15 μm, the asymptotic total fouling mass has increased over 14 times, reaching from 0.016 to 0.18 kg/m2, and the total number of deposited particles has also increased. By increasing the fluids inlet velocity from 1 to 1.5 m/s, the total number of deposited particles has decreased throughout the pipe wall, and the total fouling mass has experienced a reduction of 55.8 %.

Droplet-based microfluidics for engineering shape-controlled hydrogels with stiffness gradient

Current biofabrication strategies are limited in their ability to replicate native shape-to-function relationships, that are dependent on adequate biomimicry of shape, size and spatial heterogeneity, within cell-laden hydrogels. In this study, a diffusion-based microfluidics platform is presented that meets these needs in a two-step process. In the first step, a hydrogel-precursor solution is dispersed into a continuous oil phase within the microfluidics tubing. By adjusting the dispersed and oil phase flow rates, the physical architecture of hydrogel-precursor phases can be adjusted to generate spherical and plug-like structures, as well as continuous meter-long hydrogel-precursor phases (up to 1.75 m). The second step involves the controlled introduction a small molecule-containing aqueous phase through a T-shaped tube connector to enable controlled small molecule diffusion across the interface of the aqueous phase and hydrogel-precursor. Application of this system is demonstrated by diffusing co-initiator sodium persulfate (SPS) into hydrogel-precursor solutions, where the controlled SPS diffusion into the hydrogel-precursor and subsequent photo-polymerization allows for the formation of unique radial stiffness patterns across the shape- and size-controlled hydrogels, as well as allowing the formation of hollow hydrogels with controllable internal architectures. Mesenchymal stromal cells are successfully encapsulated within hollow hydrogels and hydrogels containing radial stiffness gradient. The cells are observed to respond to the microscale spatial heterogeneity as evidenced by increased cell elongation in softer core regions of the hydrogel as compared to the peripheral stiffer hydrogel regions, as well as stiffness-dependent nuclear accumulation of the yes-associated protein mechano-regulator. Finally, breast cancer cells are found to phenotypically switch in response to stiffness gradients, causing a shift in their ability to aggregate, which may have implications for metastasis. The diffusion-based microfluidics will mimic native shape-to-function relationship and provides a platform to further study the roles of micro- and macroscale architectural features that exist within native tissues.

Photometry, rotation period determination and dust coma numerical study of comet C/2017 K2 (PanStarrs)

C/2017 K2 (Pan-STARRS) is an Oort cloud comet discovered in May 2017. Ground observations have revealed that this long-period comet was active at a heliocentric distance beyond 20 au. Several studies observed this object when it was far from the Sun and proposed that, at such a distance, its activity is primarily driven by the sublimation of super-volatile ices such as CO and CO2.The aim of this paper is to analyze the comet’s dust behavior when it was much closer to the Sun. A series of images were taken on different observation routines between July and August 2022 with the 0.6 m Helen Sawyer Hogg (HSH) telescope at the Complejo Astronómico El Leoncito (CASLEO), using broadband V and R filters. The objective was to conduct a morphological, photometric, and numerical analysis of this comet.Digital filters were applied to enhance contrast in the cometary images, revealing an active region embedded within an isotropic coma. Analysis of the magnitudes and dust production rate from the A(0°)fρ parameter suggests a steady-state dust behavior, consistent with findings from other authors.Moreover, thanks to the images covering a significant time span, it was possible to determine the comet’s rotation period using a periodogram analysis with the Phase Dispersion Minimization method (PDM) and to calculate the coordinates of the rotation axis, yielding a rotation period of 14.24 h with a pole situated at the ecliptic longitude and latitude of (244°,−20°).Finally, to gain deeper insights into C/2017 K2’s dust behavior, observations were fitted to a newly developed theoretical model for studying dust comas. The analysis suggests that the comet’s dust coma was principally formed by large dust particles emitted at a velocity of 180ms−1.

The impact of structural properties on the absorption of hen egg-white ovotransferrin with or without Fe3+ at the air/oil-water interface

This study investigated the impact of structural changes (particle size, potential, hydrophobicity, circular dichroism spectra) in ovotransferrin with and without Fe3+ (holo-OVT and apo-OVT) on their interfacial behaviors. Holo-OVT exhibited greater diffusion, penetration, and rearrangement rates at the oil-water interface, whereas apo-OVT was detected at the air-water interface owing to the reduced hydrophobicity of air phase. Reduced hydrophobicity of both the protein (apo-OVT) and the dispersed phase (oil) leads to shorter lag periods. As for the interfacial film, holo-OVT formed denser but thinner films than those formed by apo-OVT at both interfaces, as confirmed by larger viscoelastic modulus, reduced film thickness, and lower Gibbs surface excess. These findings were likely attributable to the greater structural rigidity of holo-OVT presented with significant decreases in hydrophobicity index (432.20) than apo-OVT (522.40). Ultimately, holo-OVT exhibited significant improvements in foaming and emulsifying stability than apo-OVT.

Continuous reduction and phase transformation mechanism of pellets in lumpy zone based on dissected hydrogen blast furnace

The continuous phase transition phenomena and mechanism of pellets in the hydrogen blast furnace is achieved by dissecting the 40m3 hydrogen blast furnace. The results of the dissection reveal that the lumpy zone extends to the bosh of the hydrogen blast furnace (HBF), while it ends at about 2/3 of the stack in traditional blast furnace. The iron oxide (FeOx) began to appear in the upper stack, while the iron started to appear in the lower stack. The reduction rate and metallization rate at the bosh are measured at 95.18% and 95.54%. The content of ferrous oxide (FeO) decreases significantly (measured at 1.73% at the bosh), resulting in an increase in the melting point of the primary slag and a deterioration of its fluidity. FeOx formed in the upper stack continuously diffuses and merges into the gangue, which affects the subsequent transformation of FeOx. FeOx shows a preference for interacting with SiO2, CaO, and MgO, directly influencing the formation of slag in the cohesive zone. These findings offer valuable insights for numerical simulation and research on hydrogen-rich operation.

CFD modeling of spray drying of fresh whey: Influence of inlet air temperature on drying, fluid dynamics, and performance indicators

Whey is a very perishable food and a potent source of protein. It might be more commercialized through the process of spray drying, which would enhance its shelf life. No CFD computational models applied to the drying of fresh sweet whey have been reported in the literature to investigate transport phenomena in spray dryers and to predict crucial design parameters such as deposition, powder recovery, and drying efficiency. Using an Eulerian-Langragean technique, the behavior of multiphase flow as well as heat and mass transfer were investigated. The influence of the inlet air temperature was evaluated in relation to the velocity profiles of the continuous and discrete phases, the residence time distribution, the particle diameter formed, the air temperature near the injection zone, the particle temperature, and the mass fraction of evaporated water. Furthermore, performance parameters such as powder recovery, particle deposition, and drying efficiency were projected for varied air inlet temperatures. The velocity, residence time, and particle size distribution patterns were similar for the different air inlet temperatures. Greater variations might be noticed in the injection zone, especially in the temperature and mass fraction profiles. The lowest drying temperature resulted in the lowest particle deposition and the best thermal efficiency, making it the optimal process condition. This investigation can serve as a benchmark for the design of optimized spray dryers with greater thermal efficiency and yield to produce powdered whey.

Enhanced control and efficiency in millimeter-scale composite droplets preparation

A microfluidic device utilising the flow focusing method was designed and fabricated for the high-throughput and controllable preparation of millimeter-scale water-in-oil (W1/O/W2) droplets. Two distinct flow focusing modes were employed in order to prepare the composite droplets. In the flow-focused axisymmetric jetting mode, the continuous phase propels the dispersed phase, forming a cone, which subsequently leads to a jet formation downstream of the small hole. When the outer phase is activated, perturbation growth interferes with downstream fragmentation, resulting in composite droplets with excellent monodispersity. In the dripping mode, the dispersed phase fails to form a jet downstream, and the interface disintegrates, resulting in droplet formation at the exit of the small orifice. In the jetting mode, the size and shell-to-core ratio of the generated droplets can be controlled by adjusting the volume of flow of the outer and inner phases, as well as the applied frequency. Furthermore, the applied perturbation allows for precise control of droplet size, which significantly reduces satellite droplet formation and enhances droplet monodispersity. In the dripping mode, the shell-to-core ratio is adjusted by manipulating the ratio of inner to outer flow rates, which is tailored to the specific requirements of the flow-focused dripping mode. The prepared compound droplets exhibit good monodispersity. Finally, the rotational solidification method can be employed to obtain spherical shells with a shell thickness of less than 20 μm. In conclusion, the flow focusing method is an effective, controllable, and stable method for synthesising millimetre-sized composite droplets.

Experimental study on CO2 absorption in aqueous solutions and water–oil emulsions of TEA and blended MEA/DEA–TEA

ABSTRACT The CO2 absorptions in aqueous solutions and water-in-oil (W/O) emulsions of TEA, MEA–TEA, and DEA–TEA were investigated. By applying an experimental setup, the effects of reactant concentration (0.25–1 M for TEA, 0.1–0.3 M for MEA/DEA), temperature (15–35°C), volume fraction of the dispersed phase (0.4–0.6), and pressure (100–400 kPa) on capacity and rate of CO2 absorption were measured and compared. The CO2 absorption capacity in a TEA solution with a low/medium concentration (0.25–0.5 M) is more than the theoretical value while these values are approached to each other in the high concentration (1 M). The CO2 absorption capacity of blended solutions (MEA/DEA–TEA) is higher than that of the TEA solution. By increasing the temperature, the CO2 absorption capacities of the TEA and blended solutions are decreased by increasing the temperature. For the emulsion solutions, increasing the volume fraction of the dispersed phase causes a decrement in the capacity of absorption. In the low concentration of MEA/DEA (0.1 M), the aqueous solution has a higher absorption capacity than that of the emulsion while this trend is reverse in the high concentration of MEA/DEA (0.2–0.3 M). The CO2 absorption rates of emulsions are higher than the rates of their corresponding aqueous solutions. For the TEA solutions, the rate of CO2 absorption is controlled by the reaction rate while the shuttle mechanism enhances the absorption rate for the blended solutions. The CO2 absorption capacity and rate for the TEA and blended solutions are increased by pressure while this increment is more significant for the emulsions.

Artificial intelligence-based droplet size prediction for microfluidic system

PurposeThis study aims to introduce a vision-based model to generate droplets with auto-tuned parameters. The model can auto-adjust the inherent uncertainties and errors involved with the fabrication and operating parameters in microfluidic platform, attaining precise size and frequency of droplet generation.Design/methodology/approachThe photolithography method is utilized to prepare the microfluidic devices used in this study, and various experiments are conducted at various flow-rate and viscosity ratios. Data for droplet shape is collected to train the artificial intelligence (AI) models.FindingsGrowth phase of droplets demonstrated a unique spring back effect in droplet size. The fully developed droplet sizes in the microchannel were modeled using least absolute shrinkage and selection operators (LASSO) regression model, Gaussian support vector machine (SVM), long short term memory (LSTM) and deep neural network models. Mean absolute percentage error (MAPE) of 0.05 and R2 = 0.93 were obtained with a deep neural network model on untrained flow data. The shape parameters of the droplets are affected by several uncontrolled parameters. These parameters are instinctively captured in the model.Originality/valueExperimental data set is generated for varying viscosity values and flow rates. The variation of flow rate of continuous phase is observed here instead of dispersed phase. An automated computation routine is developed to read the droplet shape parameters considering the transient growth phase of droplets. The droplet size data is used to build and compare various AI models for predicting droplet sizes. A predictive model is developed, which is ready for automated closed loop control of the droplet generation.