Influence Of Droplet Size Research Articles

Influence of droplet size and surface hydrophobicity of soybean protein-based nanoemulsion fillers on the quality of silver carp myofibrillar protein gels

This study investigated the mechanisms underlying the influence of droplet size and emulsifier wettability on gel properties when oil-in-water (O/W) emulsions serve as fillers in myofibrillar protein (MP) gels. Pickering emulsions with varying droplet sizes were prepared using soybean protein isolate (SPI) and SPI-curcumin nanoparticles, then used to construct composite gels. Findings showed that decreased droplet size and increased emulsifier surface hydrophobicity enhanced hydrophobic interactions in the gel, increasing the β-sheet content of MP molecules. Upon the introduction of SPI-Cur-NPs stabilized nanoemulsion (SCNE), the hydrophobic force in the gel was approximately 2.6-fold more remarkable than that of the control, and the β-sheet content increased to 16.51 %. This resulted in a denser mesh framework and more uniform oil droplet distribution, increasing the hardness value from 26.993 g to 41.847 g. Moreover, SCNE addition improved gel antioxidant properties, reducing carbonyl and peroxide levels to 31.82 % and 24.15 % of the control, respectively. These findings offer insights for improving MP-based gel products.

An effective droplet sieving method by a trapezoidal stepped microchannel

The droplet sieving process in a trapezoidal stepped microchannel was visually investigated. The sieving mechanism of the small droplet and the moving trajectory of the main droplet were studied. Three flow patterns were found in the experiment: incomplete sieving, complete sieving and main droplet loss regimes. The results show that with the increase of continuous phase superficial velocity Ut, the flow pattern evolves from incomplete sieving to complete sieving and finally to the main droplet loss regimes. The continuous phase flow rate range for the complete sieving regime increases with the growth of main droplet size. Meanwhile, the influences of droplet size and flow rate of continuous phase on the sieving process were investigated. The sieving efficiency decreases with the increase of droplet size of small droplets, whereas it is almost unaffected by the main droplet size. Under the same continuous phase flow rate of regulating channel, the higher continuous phase flow rate of the main channel would lead to lower sieving efficiency.

Behavior of Compound Materials on Superhydrophobic Cylinders: Effects of Droplet’s Size and Interface Angle

Compound droplets can consist of two or more immiscible substances sharing an interface. Among such droplets, the low-viscosity component of Janus droplets can exhibit peculiar bouncing behavior on nonwettable surfaces. There have been recent advances in droplet control technologies, however the impact dynamics of droplets on complex surfaces, and strategies to control their behavior, have not been extensively studied. This study employs the volume of fluid method to analyze the effects of Janus droplet size and the initial interface angle on the dynamics of the two fluidic components in droplets on superhydrophobic cylinders. Janus droplets are composed of low-viscosity (W-) and high-viscosity liquid (G-component). The dynamic characteristics of Janus droplets are investigated as a function of Weber number (<i>We</i>), initial interface angle, the ratio of the droplet’s diameter to the cylinder’s diameter, and viscosity ratio (α). Numerical models provide a regime map of the separation ratio of Janus droplets based on We and α, and the influence of droplet size on asymmetric bouncing is discussed. This study also examines the threshold We at which separation begins after impact, varying with droplet size and α. In addition, the shape evolutions of the droplets are discussed for various initial interface angles to understand the bouncing behavior and separation efficiency. This study is expected to provide valuable strategies for controlling droplet behavior and separation in applications such as liquid purification, rheology, and solidification.

Influence of droplet size and ejection frequency on molten pool dynamics and deposition morphology in TIG-aided droplet deposition manufacturing

Droplet parameters like diameter and ejection frequency are identified as essential factors in metal-based droplet deposition manufacturing (DDM). A high-fidelity multi-physics model was developed to reproduce the improved DDM process (previously proposed as tungsten inert gas (TIG) - aided DDM) where multiple metal droplets merge with a moving molten pool to form a single track. This paper mainly discusses the influence of droplet parameters on the molten pool behaviors and deposition morphology. Two droplet sizes with different generation frequency were included in the model: high-frequency small droplet and low-frequency large droplet, however, the volume flow rate of the two cases remains same. During deposition, the significant fish-scale ripples on the top surface of deposited layers occurred from the smaller droplets into the larger ones through partial coalescence. For high-frequency small droplet mode, the shape of deposited layer is more beautiful with the surface being continuous, smooth and even. Because of differences in the physical processes involved, the relationship between droplet size mode and deposition morphology was further elaborated based on the molten pool configuration. This work provides a perspective in understanding the physical phenomena involved in TIG-aided DDM and lays the foundation for the optimization of surface macro-quality of deposits.

Investigation into the influence of droplet size on the stability of diesel emulsions based on multiple light scattering

Diesel oil emulsification is a common method to enhance the coal slime flotation, but difficult to apply industrially due to its unstable characteristics. In this paper, based on the multiple light scattering technique and the statistical Box-Behnken design (BBD) tests, the effect of the process parameters such as shear speed (A), shear time (B), and the mass ratio of SDBS to Span80 (C) on turbiscan stability index (TSI) value was systematically studied, and the relationship between emulsion stability and emulsion droplet size was also explored. The results showed that the destabilization of emulsified diesel (ED) was related to gravity migration and an increase in droplet size and was well fitted by the classical first-order kinetic model with R2 > 0.99. The significant order in which the three factors negatively affect the TSI value is, shear speed (A) > the mass ratio of SDBS to Span80 (C) > shear time (B), with shear speed ranging from 1000 to 16000 rpm, with shear time from 10 to 15 min, and with ratio of Span 80/SDBS from 0.45 to 1.48, respectively. Analysis of variance (ANOVA) revealed a high R2 value of the regression model equation (R2 = 0.9857) and fitted to a second-order polynomial equation using multiple regression analysis. The representative particle size (D50) has a positive linear correlation with the TSI value, indicating the smaller the particle size, the more stable the ED. The theoretical analysis using the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory and Stokes-Richardson-Zaki model demonstrated that the smaller ED droplets have the greater energy barrier to overcome before coalescing and lower rising velocity to move to the upper oil phase, and hence better stability.

Influence of droplet size on the antibacterial efficacy of citral and citronella oil nanoemulsions in polysaccharide coated fresh-cut apples

Fresh-cut fruits are highly perishable and susceptible to bacterial contamination. Polysaccharides edible coating loaded with essential oils nanoemulsions have the potential to extend shelf life and improve quality of fruits. The effectiveness of this approach is dependent on the properties of the nanoemulsions, such as droplet size (DS) and stability. This study aimed to optimize the production of citral (CT) and citronella oil (CTO) nanoemulsions (CT-CTO-NEs) incorporated in edible coating film to be used as natural antimicrobial agent in fresh-cut apples. After testing different combinations of surfactant (tween 80) and cosurfactant (propylene glycol) to obtain stable oil-in-water (o/w) nanoemulsions, the results demonstrated that optimized CT-CTO-NEs with DS less than 500 nm have been successfully achieved with high stability for 3 weeks at 4 °C. In addition, CT-CTO-NEs were obtained by In situ formation under magnetic stirring without applying complex high shear homogenization processes. Desired stability of CT-CTO-NEs also has been achieved within semi-solid matrix (sodium alginate cross-linked film). The relationship between DS and antibacterial activity was observed, with the smallest DS (< 100 nm) showing the highest antibacterial efficacy against Listeria monocytogenes and Escherichia coli. These results emphasize the importance of DS in the effectiveness of CT-CTO-NEs as an antibacterial coating for fresh-cut fruits.

Numerical simulation of the enhancing effect of micro–nano protrusions on electrostatic fog harvesting

Fog harvesting is one potential approach to provide supplementary water resources in arid areas. Considerable research has been devoted to electrostatic fog harvesting technology, but there are still some problems, such as high voltage, complex structures and expensive cost. Decorating micro–nano protrusions on the electrode is an effective method to lower the operating voltage and improve fog harvesting efficiency, and the enhancement effect of protrusions has already been experimentally demonstrated. However, the enhancement mechanism at the microscopic level is less reported. This manuscript tries to explain why micro–nano protrusions can enhance the discharge and electrostatic fog harvesting, via numerical simulation. Three key processes of corona discharge, fog droplet migration and fog harvesting efficiency are discussed in detail, especially the influence of droplet size, the tip radius of the protrusion, the protrusion–protrusion angle and so on. The numerical simulation results show that the inception voltage of the barbed electrode decreases from 7 kV to 3 kV (a decrease of 57%), and the current increases significantly (e.g. by 68% at 15 kV). At 15 kV, the fog harvesting efficiency of the barbed electrode is higher (29.8%) than that of the smooth wire (25.7%), even with a less-effective collection area. The collection efficiency increases with the droplet size, and there is an optimized ratio (∼1‰) of the protrusion tip radius and wire radius to gain high collection efficiency. These research results are beneficial for understanding the microscopic mechanism of protrusions that enhance electrostatic fog harvesting, and provide guidance for further fog harvesting equipment improvement.

Influence of Droplet Size and Oil Viscosity on the Descending Velocity of Droplets Using Water Model With and Without Stirring

Metal emulsions have been studied for several decades as a method of increasing the efficiency of the steelmaking process. This study was performed using a water model, observable at room temperature, to compensate for the disadvantages of the high-temperature experiment, the results of which are difficult to observe visually. As a substitute for metal-in-slag emulsions, experiments were conducted by dropping distilled water into silicone oil and comparing the results with the results of a calculation by momentum balance equations. The descending velocity of the water droplet decreased as the diameter of the droplet and viscosity of the fluid (silicon oil) increased. To simulate the descending velocity of a water droplet in silicon oil under stirring conditions, the flow rate of the fluid (silicon oil) was measured by particle image velocimetry (PIV) methods. The calculation of the descending velocity of the water droplet was in good agreement with the measured values, with and without stirring a viscous silicone oil.

Confining Trypanosoma brucei in emulsion droplets reveals population variabilities in division rates and improves in vitro cultivation

Trypanosome parasites are infecting mammals in Sub-Saharan Africa and are transmitted between hosts through bites of the tsetse fly. The transmission from the insect vector to the mammal host causes a number of metabolic and physiological changes. A fraction of the population continuously adapt to the immune system of the host, indicating heterogeneity at the population level. Yet, the cell to cell variability in populations is mostly unknown. We develop here an analytical method for quantitative measurements at the single cell level based on encapsulation and cultivation of single-cell Trypanosoma brucei in emulsion droplets. We first show that mammalian stage trypanosomes survive for several hours to days in droplets, with an influence of droplet size on both survival and growth. We unravel various growth patterns within a population and find that droplet cultivation of trypanosomes results in 10-fold higher cell densities of the highest dividing cell variants compared to standard cultivation techniques. Some variants reach final cell titers in droplets closer to what is observed in nature than standard culture, of practical interest for cell production. Droplet microfluidics is therefore a promising tool for trypanosome cultivation and analysis with further potential for high-throughput single cell trypanosome analysis.

Three-dimensional simulation of drop motion in channels of different cross-sections

Three-dimensional Boundary Element Method accelerated using a heterogeneous Fast Multipole Method is employed to study two-phase flow in a microchannel of different cross-sections. The flow of a mixture of two Newtonian liquids with equal viscosities and densities is described by Stokes equations. A comparison of the simulation results of the droplet dynamics in cylindrical capillaries with experimental data available in the literature was carried out and showed the qualitative agreement. The deformable droplet motion is considered in a channel with a circle, square, and hexagon cross-sectional shape. The influence of droplet size on a relative velocity in a channel is studied. The applied approach to numerical simulation can be used to solve a wide range of problems related to emulsion flows in microscales.

Numerical Study of Condensation Heat Transfer and Droplet Dynamics on Different Wetting Surfaces of Gas Transportation Pipelines

In this work, numerical investigation of condensation on a horizontal pipe which has various wettability properties analyzed. The influence of droplet size and contact angle on the performance of heat transfer is investigated. The condensation heat transfer obtained using MATLAB software to find the optimum function that enhances the performance. The wetting behavior is discussed under the atmospheric condition by considering the non-condensable gas. The effect of thermal boundary layers resulted from the droplet conduction, interfacial, coating, non-condensable gas, convection heat transfer was considered as well. The heat transfer rate is influenced by the droplet diameter for both hydrophilic and hydrophobic surfaces. The heat transfer rate increased by 30% when the droplet diameter is 1.5 mm than the droplet diameter is 2.5mm. The contact angle has affected the performance of heat transfer on hydrophilic surfaces.

In-flight icing simulation for two-dimensional configurations

This paper presents a comprehensive aircraft icing simulation tool implemented in an in-house Navier–Stokes parallel multi-block solver. In detail, the droplet flow field is solved by Eulerian approach, and a Partial Differential Equation (PDE)-based ice accretion model is adopted to determine the runback water flow and icing rate. Numerical validations are performed on the two-dimensional (2D) NACA 0012 airfoil, where good agreements with the literature are observed. Additionally, the paper investigates the influence of droplet size on the final ice shape. Results show that droplets with greater Median Volume Diameter (MVD) are more likely to impact on the wall, which results in larger droplet impingement limit and icing limit.

Formulation and In-vivo Studies of Clopidogrel by Self-nanoemulsifying Drug Delivery System

A self-nano emulsifying drug delivery system (SNEDDS) has been explored to improve poorly watersoluble drug clopidogrel’s solubility and dissolution rate. Different formulations were prepared using oil, surfactant, and co-surfactant in varying ratios. From the ternary phase diagram resultant formulations were investigated for clarity, phase separation, drug content, % transmittance, globule size, freeze-thaw, in vitro dissolution studies, particle size analysis, and zeta potential. Based on particle size, zeta potential and dissolution profile, and other studies, F6 was the best formulation of clopidogrel SNEDDS. The particle size of the optimized SNEDDS formulation was found to be 5.2 nm, and zeta potential was found to be -29 mV which complies with the requirement of the zeta potential for stability. The % release from optimized SNEDDS formulation F6 was highest (98.93%) and faster than other SNEDDS formulations and pure drug substance (32%), indicating the influence of droplet size on the drug dissolution rate. FTIR data revealed no physicochemical interaction between drug and excipients. In vivo bioavailability studies were carried out on the optimized formulation (F6), mean time to attain peak drug concentration (Tmax) was 0.5 ± 0.53 and 1.5 ± 0.72 minutes for the optimized and pure drug, respectively, while means maximum drug concentration (Cmax) was 6.77 ± 1.73 ng/mL and 2.10 ± 0.39 ng/mL respectively. AUC0-α and AUC0-t for the optimized formulation were significantly higher (p is less than0.05) 20.5 ± 2.48 ng.h/mL than the pure drug 6.34 ± 1.73 ng h/mL, respectively. Thus, the results indicate clopidogrel with SNEDDS formulation may be used to improve solubility and dissolution rate for the effective management of heart disease.

Calculated Study of the Influence of Overheating Aluminum Melt on the Dynamics the Granulation Process

A three-dimensional mathematical model of the solidification process of a liquid metal is considered, taking into account the mobility of the boundaries at which the phase transition is carried out (Stefan boundary value problem). The algorithm of calculation is improved, allowing due to the use of the Dirac δ-function in determining the effective heat capacity to take into account the nonlinearity of the equation of unsteady thermal conductivity and the heat of the phase transition. A numerical study of heat transfer during solidification of lead-containing aluminum melt droplets in air and water is carried out. The influence of droplet size and melt overheating on the solidification dynamics of granules has been studied. An approximate ratio based on the square root law is proposed, taking into account the amount of overheating of the liquid phase and linking the thickness of the formed solid phase with the duration of the granulation process

Effect of spray volume, application timing and droplet size on spray distribution and control efficacy of different fungicides against circular leaf spot of persimmon caused by Plurivorosphaerella nawae

In recent years, Spain has been the scenario of the largest production growth of persimmon worldwide. However, circular leaf spot of persimmon, caused by Plurivorosphaerella nawae, was responsible for causing severe yield and economic losses. This work studied the effect of spray volume rate, droplet size, and application timing on spray distribution and disease control efficacy for mancozeb, pyraclostrobin and difenoconazole applications. Also fungicide degradation dynamics on persimmon leaves were studied. A method to inoculate persimmon plants using natural inoculum of P. nawae was developed. Results showed that spray volume influenced canopy spray coverage regardless of the fungicide used, but it did not influence disease control efficacy, except when pyraclostrobin was applied as pre-inoculation spray. Pyraclostrobin also showed a good post-inoculation activity. Influence of droplet size on spray coverage depended on the leaf side considered but it did not affect disease control efficacy except for pyraclostrobin applied 14 days after inoculation, when coarse droplets had lower control than fine ones. In general, slight degradation dynamics of fungicide residues on leaves were observed at 14 days.

Molecular Dynamics Analysis on the Wetting Properties of R32, R1234yf, and Their Mixture on Pillar-Type Nanostructured Substrates.

Understanding the wetting characteristics of a droplet on a solid surface is an important topic in basic research and various engineering applications. The further understanding of wetting characteristics of working fluid is very valuable for revealing the mechanism of phase change heat transfer, especially for understanding the complex phenomena of phase change heat transfer of mixtures. In this study, the wetting behaviors of R32, R1234yf, and R32/R1234yf nanodroplets on square pillar-type substrates were investigated by molecular dynamics simulations. The influences of structure size, droplet composition, and droplet size on the position of the critical line were investigated in particular. The results show that the droplet tends to be the Cassie state with higher pillar and shorter spacing. The influence of droplet composition on wetting state conversion is approximately linear with concentration. The influence of droplet size is relatively small. The results are reasonably explained by the force analysis method proposed in this paper.

Adhesion of a water droplet on inclined hydrophilic surface and internal fluidity

A water droplet attachment on a hydrophilic surface with inclination is investigated. The influence of droplet size and the inclination angle of the surface on the droplet adhesion are examined. Height and lateral extension of the droplet on the inclined hydrophilic surface are formulated and the findings are compared with the experimental data. The hydrodynamic response of the droplet due to inclination of the surface is simulated and the flow field inside the droplet is predicted for various droplet inclination angles of the surface and the droplet size. An experiment is designed to validate the flow field predicted inside the droplet via incorporating particle image velocimetry (PIV). It is found that the velocity predicted agrees well with the PIV data. A circulation cell is developed inside the droplet and the rotational center and the strength of the fluid circulation change with the inclination angle and the droplet size. The adhesion force increases with increasing inclination angle of the surface and the droplet size. The shear force generated at the wetted surface contributes to the adhesion force; however, this contribution is not significant.

Impact of Water Mist Thickness on Shock Wave Attenuation

Explosion protection systems for underground structures are designed to create a suppressing barrier between the site of explosion and the facility to be protected. Studies have shown that water mist, provided that its properties are correctly selected, can effectively reduce shock wave overpressure in tunnels. The influence of droplet sizes and concentration of water in mist on shock wave mitigation processes have been studied by various researchers through experiments and modelling. However, the effect of geometric dimensions of mist on shock wave attenuation in tunnels has not been sufficiently studied.This paper addresses the influence of water mist thickness on blast overpressure under identical mist properties and explosion conditions in the tunnel. The study of such influence is essential for the proper design of the protective system. Experiments were conducted in the tunnel of the underground experimental base of the Mining Institute, Tbilisi, Georgia. The methodology employed envisaged the measurement of overpressures in the tunnel with the mist generated by the spray system. At different stages of experiments, the water mist thickness was 1.6m, 2.6m and 3.8m. Experiments were carried under the following conditions: charge weight - 2 kg; distance from the charge to the mist - 3.5 m, from the charge to the sensors - 11.5 m, droplet size distribution - 10-260μm, Mist density - 1.45 l/s•m3. In the test zone the height of the tunnel was 2.2 m, width - 2.2 m, cross-section - 4.4m2. The results of the experiments showed that the water mist thickness has an influence on the shock wave overpressure. Under the conditions of experiments carried out by us, the increase of the mist thickness by 3.1 times allowed to reduce the overpressure by 34%.

Experimental modulation and theoretical simulation of zonal oscillation for electrostatically levitated metallic droplets at high temperatures

The second- and third-order zonal oscillations of metallic droplets at high temperatures beyond 2000 K were experimentally achieved by electrostatic levitation. To quantitatively describe the suspension stability of different metallic droplets, a stability factor model was proposed as a function of the surface tension and density. The influences of droplet size and temperature on the oscillation pattern, oscillation frequency, and oscillation amplitude were analyzed. As a supplement to experiment, a feasible mathematical model of droplet deformation and oscillation, coupling the effects of electrostatic and flow fields, was established to study the underlying mechanism of droplet dynamics at high temperatures. The simulation not only reproduced the experimental observations, but also predicted the evolution characteristics of higher-order oscillations. The inherent relationships between the oscillation frequency and the droplet size, density, and surface tension of liquid metals were systematically investigated by simulation. Moreover, the suspension stabilities of nine typical metallic droplets were derived and compared with the simulation results.

Influence of Dairy Emulsifier Type and Lipid Droplet Size on Gastrointestinal Fate of Model Emulsions: In Vitro Digestion Study.

Human breast milk is a natural emulsion containing relatively large triacylglycerol droplets coated by a distinct interfacial layer known as the milk fat globule membrane (MFGM). The unique properties of the MFGM impact the release of nutrients from breast milk in an infant's gastrointestinal tract (GIT), but the membrane architecture is susceptible to disruption by industrial processes. To formulate infant formula that simulates the gastrointestinal behavior of breast milk, food manufacturers require knowledge of the impact of the interfacial properties on the gastrointestinal fate of fat globules. In this study, a simulated GIT was utilized to monitor the gastrointestinal fate of emulsified corn oil with different dairy emulsifiers, including sodium caseinate, lactoferrin (LF), whey protein isolate (WPI), and milk phospholipids (MPL) isolated from MFGM. The influence of droplet size on the gastrointestinal fate of the MPL-stabilized emulsions was also examined. Our findings provide valuable information for the optimization of infant formula and dairy-based nutritional beverages.