Droplet Size Distribution Profile Research Articles

Resilient dataset of rain clusters with life cycle evolution during April to June 2016–2020 over eastern Asia based on observations from the GPM DPR and Himawari-8 AHI

Abstract. Our knowledge of the properties of precipitation and clouds over their life cycles has progressed with the rapid development of satellite observations. However, previous studies have focused on the life cycle evolution of the macroscale features of precipitation and clouds, whereas the evolution of the microphysical properties of precipitation and clouds over their life cycles is yet to be determined. One of the reasons for this lack of knowledge is the fact that there is no single dataset providing both the three-dimensional structure of precipitation and the relevant life cycle properties. We identified initial rain clusters (RCs) from the Global Precipitation Measurement (GPM) 2ADPR dataset and mesoscale convective systems (MCSs) from the Himawari-8 Advanced Himawari Image (AHI) gridded product. Based on the contours of the initial RCs and MCSs, we then carried out a series of resilient processes, including filtration, segmentation, and consolidation, to obtain the final RCs. The final RCs had a one-to-one correspondence with the relevant MCS. We extracted the RC area, central location, average radar reflectivity profile, average droplet size distribution profile, and other precipitation information from the contours of the final RCs and GPM 2ADPR dataset. The life cycle evolution of the MCS area, location, and cloud-top brightness temperature were retrieved from the corresponding MCSs and their tracks from Himawari-8 observations. The final dataset provides both three-dimensional precipitation information and life cycle information of precipitating clouds during April to June 2016–2020 over eastern Asia. This dataset facilitates studies of the life cycle evolution of precipitation and provides a good foundation for convection parameterizations in precipitation simulations. The dataset used in this paper is freely available at https://doi.org/10.5281/zenodo.6198716 (Zhang et al., 2022).

Effect of water chemistry on the stability of water-in-crude oil emulsion: Role of aqueous ions and underlying mechanisms

Recent studies have shown that although low salinity waterflooding leads to promising EOR impacts, it is to blame for the formation of unwanted water-in-oil emulsions. Thus, this study aims to explore the effect of water chemistry, namely ionic strength and ion types on the stability of natural water-in-oil (W/O) emulsions at the reservoir temperature of 80 °C. To this end, seawater and its dilutions with different concentrations of potential determining ions (PDIs) were used as the aqueous phase. The experimental study was performed by tracking the emulsion droplet size distribution, phase separation study and also IFT measurements. Results showed that the higher the ionic strength of the aqueous phase, the lower the W/O emulsion stability, which could be explained based on the salting-out mechanism. It was found that the IFT parameter did not significantly contribute to the emulsion stability. Regarding the effect of ion types on the stability of emulsions prepared by eight-time diluted seawater with different PDIs, the trend was Mg2+≥ Ca2+> SO42−. These observations were described in the light of the higher tendency of divalent cations to bond with crude oil polar components. As to the phase separation study, the amount of expelled water in the presence of Mg2+ was 15 vol% of the initial water, compared to 24 vol% for Ca2+ and almost half for SO42− after one-day aging. It was also found that the co-existence of sulfate with divalent cations improved the emulsion stability, while the less stable emulsions were obtained by the sulfate-rich brine. This was further supported by the droplet size distribution profile in which a more uniform profile was obtained for emulsions with the co-existence of sulfate and divalent cations as compared to the sulfate-rich samples. Results of this study addressed that the ionic strength of the aqueous phase coupled with its ionic content regulates the emulsion stability, such that there exists a specific range of salinity and ion concentration beyond that the emulsion stability may impair.

Comparison of plasma and pulmonary availability of chlorogenic acid, forsythiaside A and baicalin after intratracheal and intravenous administration of Shuang-Huang-Lian injection

Ethnopharmacological relevanceThe off-label nebulization of Shuang-Huang-Lian (SHL) injection is often utilized to treat respiratory tract infections in China. However, the pulmonary biopharmaceutics of SHL was generally unknown, limiting the rational selection of therapeutic dose and dose frequency. Aim of the studyTo characterize the size distribution of nebulized aerosols and to compare the pharmacokinetics and the lung distribution of three chemical makers of SHL, chlorogenic acid (CHA), forsythiaside A (FTA) and baicalin (BC), after intratracheal and intravenous administration of SHL to rats. Materials and methodsThe droplet size distribution profiles over nebulization process were dynamically monitored using a laser diffraction method whereas the levels of CHA, FTA and BC in plasma, lung tissues and bronchoalveolar lavage fluids (BALF) were determined by a validated LC-MS/MS assay. The pulmonary anti-inflammatory efficacy was evaluated using a lipopolysaccharide (LPS) induced lung inflammation model as indicated by the level of tumor necrosis factor-α (TNF-α) in BALF. ResultsThe nebulization of SHL showed good inhalability and allowed the aerosols to reach the upper or lower respiratory tract dependent on the performance of selected nebulizers. Following intratracheal administration of SHL at different doses, CHA, FTA and BC were absorbed into the bloodstream with the mean absorption time being 67.5, 63.5 and 114 min, respectively, rendering mean absolute bioavailabilities between 42.4% and 61.4% roughly independent of delivered dose. Relative to the intravenous injection, the intrapulmonary delivery increased the lung-to-plasma concentration ratios of CHA, FTA and BC by more than 100 folds and markedly improved the lung availability by 563–676 folds, leading to enhanced and prolonged lung retention. The production of TNF-α in BALF was decreased by ~50% at an intratracheal dose of 125 μL/kg SHL to LPS-treated mice. ConclusionThe nebulization delivery of SHL is a promising alternative to the intravenous injection for the treatment of respiratory tract infections.

Experimental Investigation of Spray Characteristics of Pre-Filming Air-Blast Atomizers II – Influence of Liquid Properties

One of the most important advantages of twin-fluid atomizers over other atomizers is the opportunity of atomizing liquids in a wide range of liquid properties efficiently. Thus, the fundamentals of spray dynamics, such as spray pattern, liquid breakup length, and spatial droplet size evolution using different liquid properties need to be investigated in some detail. The purpose of this study is therefore to examine and describe the influence of the liquid viscosity and surface tension on the spray performance of prefilming air-blast atomizers. A high-speed background shadowgraphy technique associated with particle tracking and Phase Doppler Anemometry (PDA) as a non-intrusive high-resolution local measurement technique were utilized to study the atomization process regarding the influence of the liquid properties on the spray quality. Generally, the break up mechanism is considerably influenced by the liquid viscosity. The breakup length ( ) is dependent on liquid viscosity with for Pa = 0.25 and 0.6 bar air pressure, respectively. Droplet size distribution profiles of different liquids in axial and radial directions are studied. No significant influences of the surface tension and viscosity were observed on the mean droplet velocity downstream of the spray. A minor increase of the droplet mean diameter was observed with liquid viscosity variations from 22 to 111 mPas, however, the liquid surface tension was verified to play an important role in the atomization process at prefilming airblast atomizers as well. According to the available experimental data, it has subsequently been possible to develop an original and descriptive model based on a dimensional approach at different air pressure ranges.

Droplet size distribution and mixing hydrodynamics in a liquid–liquid stirred tank by CFD modeling

Stirred tanks are the common unit operations employed for liquid–liquid dispersion in many industries. In this study, computational fluid dynamic (CFD) coupled with population balance modeling (PBM) were applied to simulate mixing of water in crude oils in a stirred tank equipped with Rushton turbine. An Eulerian multiphase model and standard k-ε turbulence model were employed to simulate the flow field inside the tank. Experimental results were then used to validate simulation results. The effect of impeller speed, volume fraction of dispersed phase, and oil viscosity on droplet size distribution were investigated in this work. An increase in agitation speed was found to decrease the mean and Sauter mean diameter while increasing the homogeneity of the system. A wider droplet size distribution profile was achieved at higher oil volume fractions with almost no significant change in droplet size. Additionally, increasing the viscosity of the oil phase resulted in a gradual shift towards smaller droplets and narrower droplet size distribution. Liquid–liquid dispersions were occurred in two different turbulent regimes depending on the viscosity of continuous phase. Related correlations for each regime were obtained and the values of maximum droplet size were fitted with the dimensionless numbers.

CFD modeling of the creaming zone of batch gravity separation with coalescence

Gravity separation of liquid-liquid dispersions is present in many industrial applications, and it involves the complex governing mechanisms of creaming and coalescence in concentrated mixtures. The aim of this work is to model the laminar creaming zone of batch gravitational separation with coalescence using CFD tools. The numerical results were compared to the experimental decay curves of bottle tests. The initial DSD representation by the population balance model was obtained with the Gauss-Legendre Quadrature. The number of velocity groups and the application range of the drag modifier showed to be a function of the initial DSD profile and polydispersity, respectively. The coalescence models evaluated were the constant coalescence efficiency, the critical approach velocity and the film drainage for a deformable partially mobile interface. The coalescence models parameters were calibrated for a determined initial condition (phases volume fraction and droplet size distribution (DSD)) and then applied for different initial conditions. All models were able to model the separation of all initial conditions with the same calibrated parameters, although the drainage model did not need to be calibrated. This suggests that when employed in the modeling of a continuous separator, these can be calibrated by the decay curves of bottle tests.

Stabilization of Dispersed Oil Droplets in Nanoemulsions by Synergistic Effects of the Gemini Surfactant, PHPA Polymer, and Silica Nanoparticle.

Nanoemulsion systems comprising n-heptane (oleic component), stabilized by the {gemini surfactant (14-6-14 GS) + polymer [partially hydrolyzed poly-acrylamide (PHPA)] + silica (SiO2) nanoparticle} shell and dispersed in aqueous phase, were synthesized by ultrasonication (high-energy method). Influence of ultrasonication time on nanoemulsion kinetics was investigated to predict the saturation droplet diameter. Morphological analysis by transmission electron cryomicroscopy imaging showed that oleic phase appears as uniformly dispersed spherical droplets in 14-6-14 GS-stabilized nanoemulsion, which on PHPA addition changes into a network structure consisting of larger oil droplets. 14-6-14 + PHPA + SiO2 nanoemulsion systems show more effective packing arrangement with irregular-shaped (nonspherical) droplets. Dynamic light scattering studies identified droplet size distribution profiles in the range 4.2-25.4 nm for the surfactant-stabilized nanoemulsion, 125.9-358.8 nm for the surfactant-polymer nanoemulsion, and 88.4-222.3 nm for the surfactant-polymer-nanoparticle-based nanoemulsion in optimal dosage(s). Statistical analyses were performed using normal, log-normal, and Cauchy-Lorentz distribution functions. A modified form of Hinze theory was employed to model droplet behavior in analyzed nanoemulsion systems. Zeta potential values of nanoemulsions were studied at different time intervals to determine kinetic stability as well as corroborate Hinze model findings. In summary, this article aims at investigating nanoemulsion droplet stability by thorough examination of electrostatic repulsive barrier and steric hindrance effects.

Influence of pH value on microstructure of oil-in-water emulsions stabilized by chickpea protein flour.

Food industry is highly interested in the development of healthier formulations of oil-in-water emulsions, stabilized by plant proteins instead of egg or milk proteins. These emulsions would avoid allergic issues or animal fat. Among other plant proteins, legumes are a cost-competitive product. This work evaluates the influence of pH value (2.5, 5.0 and 7.5) on emulsions stabilized by chickpea-based emulsions at two different protein concentration (2.0 and 4.0 wt%). Microstructure of chickpea-based emulsions is assessed by means of backscattering, droplet size distributions and small amplitude oscillatory shear measurements. Visual appearances as well as confocal laser scanning microscopy images are obtained to provide useful information on the emulsions structure. Interestingly, results indicate that the pH value and protein concentration have a strong influence on emulsion microstructure and stability. Thus, the system which contains protein surfaces positively charged shows the highest viscoelastic properties, a good droplet size distribution profile and non-apparent destabilization phenomena. Interestingly, results also reveal the importance of rheological measurements in the prediction of protein interactions and emulsion stability since this technique is able to predict destabilization mechanisms sooner than other techniques such as backscattering or droplet size distribution measurements.

Improvement of an In Vitro Model to Assess Delivered Dose and Particle Size for a Vibrating Mesh Nebulizer During Mechanical Ventilation.

In an in vitro model of mechanical ventilation with gravity-dependent filter position we observed artificially high delivered doses resulting from liquid droplet collection and precipitation of aerosolized drug. We sequentially modified the model to obtain accurate reproducible measurements of delivered dose and particle size at endotracheal tube exit. Stepwise changes in the model included (1) altering the endotracheal tube position to a gravity-independent position, (2) adding fluid traps, (3) humidifying air near the test lung, and (4) simplifying test lung and filters. Delivered dose of aerosolized vancomycin and losses in different compartments were assessed under low-flow and high-flow conditions, with or without circuit humidification. Droplet size distribution (DSD) of aerosolized Amikacin Inhalation Solution at endotracheal tube exit was measured by laser diffraction. Changing endotracheal tube position and adding traps allowed separation of liquid droplets and aerosolized drug, providing a delivered vancomycin dose of 35.1% (high flow). Active heated humidification of exhaled air significantly reduced delivered dose (21.0%) and dose variability. Simplification of the model to improve usability had no further effect on delivered dose, which was higher under low-flow than high-flow conditions, although there was no difference between humidified (high flow, 20.3%; low flow, 45.8%) and nonhumidified (high flow, 22.8%; low flow, 47.3%) conditions. With circuit humidification, drug loss decreased in endotracheal tube and nebulizer T-piece, whereas more drug was captured in traps. Lower inspiratory flow and humidity in the circuit were associated with higher Dv50 of aerosolized Amikacin Inhalation Solution at endotracheal tube exit. We successfully modified our in vitro model of mechanical ventilation to allow more accurate measurement of the delivered dose of aerosolized vancomycin and DSD profile of aerosolized Amikacin Inhalation Solution at the endotracheal tube exit.

Towards better characterization and quantification of emulsification of silicone oil invitro.

Emulsification is related to complications arising from silicone oil (SO) tamponade. Currently, there is no widely accepted method for testing the propensity of SO to emulsify that are physiologically realistic and quantitative. We compared different ways of inducing emulsification namely vortex mixing, sonication and homogenization. Silicone oil (SO) emulsification was quantitatively assessed using the Coulter counter and laser light scattering. The invitro results are compared with the droplet size distribution profile of vitreous clinical washout. Conventional SO was compared with two novel SO blends with high-molecular-weight (HMW) additives (SOHMW2000 and SOHMW5000 ). Of the three methods for inducing emulsification, homogenization generated the most consistent emulsion samples with the smallest variance. The results from the Coulter counter measurement correlated strongly with the laser light scattering measurement within the range of 1 to 30µm. The droplet size distribution profiles from human eyes were similar to that of emulsions generated invitro by homogenization. The human size distribution profile was within the range of values obtained by the invitro experiment. Compared to the conventional SO, the emulsion droplet counts for the new SO blends were significantly lower (SOHMW2000 and SOHMW5000 were 79% (±17%) and 49% (±18%) of the SO2000 and SO5000 , respectively; p=0.03 and p=0.002). Emulsion generated invitro by homogenization has similar droplet size profile as human eyes filled with SO. Using this method to induce emulsion, SO blends with HMW additives demonstrated less propensity to emulsification with lower droplet counts compared to conventional SO with similar shear viscosity.

Systematic Multi‐Scale Model Development Strategy for the Fragrance Spraying Process and Transport

AbstractThe fast and efficient development and application of reliable models with appropriate degree of detail to predict the behavior of fragrance aerosols are challenging problems of high interest to the related industries. A generic modeling template for the systematic derivation of specific fragrance aerosol models is proposed. The main benefits of the fragrance spraying template are the speed‐up of the model development/derivation process, the increase in model quality, and the provision of structured domain knowledge where needed. The fragrance spraying template is integrated in a generic computer‐aided modeling framework, which is structured based on workflows for different general modeling tasks. The benefits of the fragrance spraying template are highlighted by a case study related to the derivation of a fragrance aerosol model that is able to reflect measured dynamic droplet size distribution profiles for limonene.