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[Display omitted] Two major protein families are present in rapeseed, namely cruciferins and napins. The structural differences between the two protein families indicate that they might behave differently when their mixture stabilises oil–water interfaces. Therefore, this work focuses on elucidating the role of both proteins in interface and emulsion stabilisation. Protein molecular properties were evaluated, using SEC, DSC, CD, and hydrophobicity analysis. The oil–water interface mechanical properties were studied using LAOS and LAOD. General stress decomposition (GSD) was used as a novel method to characterise the nonlinear response. Additionally, to evaluate the emulsifying properties of the rapeseed proteins, emulsions were prepared using pure napins or cruciferin and also their mixtures at 1:3, 1:1 and 3:1 (w:w) ratios. Cruciferins formed stiff viscoelastic solid-like interfacial layers (G s ′ = 0.046 mN/m; E d ′ = 30.1 mN/m), while napin formed weaker and more stretchable layers at the oil–water interface (G s ′ = 0.010 mN/m; E d ′ = 26.4 mN/m). As a result, cruciferin-formed oil droplets with much higher stability against coalescence (coalescence index, CI up to 10%) than napin-stabilised ones (CI up to 146%) during two months of storage. Both proteins have a different role in emulsions produced with napin-cruciferin mixtures, where cruciferin provides high coalescence stability, while napin induces flocculation. Our work showed the role of each rapeseed protein in liquid–liquid multiphase systems. [ABSTRACT FROM AUTHOR]

Colored oil droplets are a common feature in the cones of almost all diurnal lizards. Using white light microscopy, three chromotypes of droplet can be identified in anoles – yellow, green and colorless. These droplets have been associated with different cone classes using microspectrophotometry. The principal member of double cones contain a yellow droplet while the accessory member contains a diffuse yellow pigment. Both members contain the LWS visual pigment. One class of large single cone contains a yellow droplet and the LWS visual pigment. The two remaining classes of large single cone contain the green droplet and either the LWS or MWS visual pigment. As such, by noting the distribution and numbers of the different droplet chromotypes, information about cone distribution, type, and number can be deduced microscopically. Retinas from three anole species (A. cristatellus, A. sagrei, and A. carolinensis) were isolated, flattened and oriented using the two foveae as landmarks. A 19-gauge needle was used to punch out six full-thickness retinal disks from identical retinal regions from both eyes of the three species. The different oil droplets were microscopically identified by color and counted. In all three species at all six retinal areas, the colorless droplets associated with the UVS and SWS single cones represented approximately 10% of the total droplets counted. However, the proportions of the yellow and green droplets were significantly different between the species. For A. cristatellus, 80% of the droplets were green while 10% were yellow. For A. sagrei approximately 85% of the droplets were yellow while only 5% were green. For A. carolinensis 50% of the droplets were yellow while 40% were green. The possible significance of these variable proportions is discussed in terms of possible effects on color vision and ecotype of the three anoles.

Emulsion systems are extensively used in the food processing sector and the use of natural emulsifiers like proteins for stabilizing emulsion has been in demand from consumers due to increased awareness about the consumption of healthy food. Numerous methods are available for the preparation of emulsion, but ultrasound got more attention among common methods owing to its economical and environment-friendly characteristics. The physical effects caused by to bursting of the cavity bubble, result in reduced droplet size, thus forming an emulsion with appreciable stability. Ultrasound ameliorates the emulsifying characteristics of natural emulsifiers like protein and improves the storage stability of the emulsion by positively boosting the rheological, emulsifying characteristics, improving zeta potential, and reducing average droplet size. The stability of protein-based emulsion is affected by environmental stresses hence conjugate of protein with polysaccharide showed good emulsifying characteristics. However, the data on the effect of ultrasound parameters on emulsifier properties is lacking and there is a need to develop a sonication device that can carry out large-scale emulsification operation. The review covers the principles and mechanisms of ultrasound-assisted formation of protein-based and protein-based conjugate emulsions. Further, the effect of ultrasound on various characteristics of protein-based emulsion is also explored. This review will provide concise data to the researchers to extend their experiments in the area of ultrasound emulsification which will help in commercializing the technology at the industrial scale.

This research aims to analyze the forces that affect oil droplets to illustrate that augmenting the mass of an oil droplet fosters favorable conditions for interaction between displaced and displacing fluids. This, in turn, impedes the bypassing of the displacing fluid around the oil droplets. In this investigation, the concept of augmenting the mass of an oil droplet is realized through absorption phenomena, employing coated spinel oxide (cobalt ferrite oxide) nanoparticles (CFO NPs). The synthesis of CFO NPs was successfully carried out in the laboratory using a sol-gel technique, followed by coating with a surfactant and lauric acid. The coated spinel oxide NPs underwent characterization using IR, XRD, and XRF techniques. The procedures started with the calculation of capillary force restrictions for small and large oil droplets. Furthermore, practical experiments involving oil droplets on glass plates at a 30° angle were conducted for different scenarios: without water injection, with water injection, and during the “absorption effect” of CFO NPs. The findings revealed that a large oil droplet exhibits lower capillary pressure restrictions compared to a small oil droplet, with a disparity of 0.02 m/s2 . Consequently, it is comparatively easier for large oil droplets to become free than small ones. Moreover, a large oil droplet exhibits faster movement than small oil droplets due to gravitational effects in the absence of any injections. During the water injection scenario, the water droplets were unable to displace the oil droplet; instead, they passed through the passage beside and above the oil droplet consistently with an increase in the amount of water droplets. However, in the coated CFO NPs scenario, absorption of the coated CFO NPs onto the oil droplet was observed. This resulted in the aggregation of oil molecules, augmenting the gravity of the oil droplet and creating favourable conditions for its displacement. Notably, no water bypass beside the oil droplet was observed in this scenario, unlike the water scenario. Additionally, the aggregation of oil molecules induced corner flow, providing conducive conditions for microemulsion formation, altering wettability, modifying residual oil saturation, and enhancing injection performance. Euler’s equation was employed to analyse corner flow, indicating that the level of oil deformation increases with the rising rotation velocity, potentially leading to an increased recovery factor.

Key message Hereby, we present a rare case of a resected endobronchial tumour that floated or showed oil droplets in saline. In this study, we report an interesting image related to endobronchial lipomatous hamartoma cryotherapy.

Investigating the motion of discrete oil droplets in a rotating flow field can provide a theoretical basis for optimizing the flow field and structural parameters of hydrocyclones and centrifugal separation equipment. In the present work, the particle image velocimetry (PIV) method was applied to study the velocity distribution of a three-dimensional axial-rotor-driven rotating flow field and the influence of the velocity distribution of different rotor speeds on the flow field. The radial migration of oil droplets with different particle sizes in the rotating flow field was visually analyzed using high-speed video (HSV). The results showed that the oil droplets with the same radial position had diameters of 2.677 and 4.391 mm, whereas the movement times to the axis were 0.902 and 0.752 s. The larger the oil droplet size, the shorter the time to move to the axial center of the rotating flow field. The radial velocities of oil droplets with diameters of 2.677 and 2.714 mm were 0.0221 and 0.02 m·s−1, respectively. In addition, a mathematical expression was established between the radial migration time and the oil droplet size in the rotating flow field. The accuracy of the proposed expression was verified using experiments. [ABSTRACT FROM AUTHOR]

Both oil spill and microplastics (MPs) are major issues in marine environments. After a spill, the oil film may disperse into the water column as droplets under the function of sea waves. The oil dispersion may be affected due to the attachment of oil to MPs. In this paper, the impacts of salinity and temperature on the dispersion of spilled oil in the presence of MPs were individually studied by batch conical flask oscillation experiments. The results indicated that the rise in salinity or temperature displayed a more significant effect on promoting, rather than inhibiting, oil dispersion with MPs. When the salinity rose from 15% to 35%, the oil dispersion efficiency (ODE) with the 13 μm polyethylene (PE) and polystyrene (PS) MPs was increased by 10.4% and 12.9%, respectively; when the temperature rose from 10 °C to 25 °C, the corresponding ODE was increased by 15.6% and 12.7%, respectively. In addition, the volumetric mean diameter (VMD) of the dispersed oil droplets decreased with an increase in salinity or temperature. Furthermore, the 13 μm MPs showed a higher impact on the oil dispersion than 106 μm of MPs, and the ODE with PE MPs was greater than that with PS MPs. The findings of this study expanded the understanding of the migration of spilled oil in seawater in the presence of MPs and may further improve the capability of predicting the impact of oil spills by marine environment managers. [ABSTRACT FROM AUTHOR]

Previous studies have been carried out on the effect of silica nanoparticles (SNPs) on the stability of oil–water emulsions. However, the combining configuration of SNPs and oil droplets at the molecular level and the effect of SNP content on the coalescence behavior of oil droplets cannot be obtained through experiments. In this paper, molecular dynamics (MD) simulation was performed to investigate the adsorption configuration of hydrophilic SNPs in an O/W emulsion system, and the effect of adsorption of SNPs on coalescence of oil droplets. The simulation results showed: (i) SNPs adsorbed on the surface of oil droplets, and excessive SNPs self-aggregated and connected by hydrogen bonds. (ii) Partially hydrophilic asphaltene and resin molecules formed adsorption configurations with SNPs, which changed the distribution of oil droplet components. Furthermore, compared with hydrophobic asphaltene, the hydrophilic asphaltene was easier to combine with SNPs. (iii) SNPs would extend the oil droplet coalescence time, and the π–π stacking structures were formed between asphaltene and asphaltene or resin molecules to enhance the connection between oil droplets during the oil droplet contact process. (iv) Enough SNPs tightly wrapped around the oil droplet, similar to the formation of a rigid film on the surface of an oil droplet, which hindered the contact and coalescence of components between oil droplets. [ABSTRACT FROM AUTHOR]

Investigating the motion of discrete oil droplets in a rotating flow field can provide a theoretical basis for optimizing the flow field and structural parameters of hydrocyclones and centrifugal separation equipment. In the present work, the particle image velocimetry (PIV) method was applied to study the velocity distribution of a three-dimensional axial-rotor-driven rotating flow field and the influence of the velocity distribution of different rotor speeds on the flow field. The radial migration of oil droplets with different particle sizes in the rotating flow field was visually analyzed using high-speed video (HSV). The results showed that the oil droplets with the same radial position had diameters of 2.677 and 4.391 mm, whereas the movement times to the axis were 0.902 and 0.752 s. The larger the oil droplet size, the shorter the time to move to the axial center of the rotating flow field. The radial velocities of oil droplets with diameters of 2.677 and 2.714 mm were 0.0221 and 0.02 m·s−1, respectively. In addition, a mathematical expression was established between the radial migration time and the oil droplet size in the rotating flow field. The accuracy of the proposed expression was verified using experiments.

• Proteins can be used as emulsifiers due to their amphiphilic nature. • Cavitation events in sonication reduce the droplet size of the emulsion and enhance its stability. • Ultrasound ameliorates the emulsifying characteristics of natural emulsifiers like protein and improves the storage stability of the emulsion. • The study on sonication-assisted formation of protein-based stable emulsion is still limited. Emulsion systems are extensively used in the food processing sector and the use of natural emulsifiers like proteins for stabilizing emulsion has been in demand from consumers due to increased awareness about the consumption of healthy food. Numerous methods are available for the preparation of emulsion, but ultrasound got more attention among common methods owing to its economical and environment-friendly characteristics. The physical effects caused by to bursting of the cavity bubble, result in reduced droplet size, thus forming an emulsion with appreciable stability. Ultrasound ameliorates the emulsifying characteristics of natural emulsifiers like protein and improves the storage stability of the emulsion by positively boosting the rheological, emulsifying characteristics, improving zeta potential, and reducing average droplet size. The stability of protein-based emulsion is affected by environmental stresses hence conjugate of protein with polysaccharide showed good emulsifying characteristics. However, the data on the effect of ultrasound parameters on emulsifier properties is lacking and there is a need to develop a sonication device that can carry out large-scale emulsification operation. The review covers the principles and mechanisms of ultrasound-assisted formation of protein-based and protein-based conjugate emulsions. Further, the effect of ultrasound on various characteristics of protein-based emulsion is also explored. This review will provide concise data to the researchers to extend their experiments in the area of ultrasound emulsification which will help in commercializing the technology at the industrial scale. [ABSTRACT FROM AUTHOR]

Both oil spill and microplastics (MPs) are major issues in marine environments. After a spill, the oil film may disperse into the water column as droplets under the function of sea waves. The oil dispersion may be affected due to the attachment of oil to MPs. In this paper, the impacts of salinity and temperature on the dispersion of spilled oil in the presence of MPs were individually studied by batch conical flask oscillation experiments. The results indicated that the rise in salinity or temperature displayed a more significant effect on promoting, rather than inhibiting, oil dispersion with MPs. When the salinity rose from 15% to 35%, the oil dispersion efficiency (ODE) with the 13 μm polyethylene (PE) and polystyrene (PS) MPs was increased by 10.4% and 12.9%, respectively; when the temperature rose from 10 °C to 25 °C, the corresponding ODE was increased by 15.6% and 12.7%, respectively. In addition, the volumetric mean diameter (VMD) of the dispersed oil droplets decreased with an increase in salinity or temperature. Furthermore, the 13 μm MPs showed a higher impact on the oil dispersion than 106 μm of MPs, and the ODE with PE MPs was greater than that with PS MPs. The findings of this study expanded the understanding of the migration of spilled oil in seawater in the presence of MPs and may further improve the capability of predicting the impact of oil spills by marine environment managers.

Lubrication failure of bearing is one of the important factors that limit the service life of the space shafting system. Due to the strict restrictions on the volume and weight, the traditional oil supply devices are difficult to meet the requirements of space active lubrication. In this article, we propose a piezoelectric microjet, which can achieve active lubricating for bearings of space equipment serving in a harsh environment. A constant pressure oil storage system, with a storage capacity of more than 4 g and can achieve vacuum oil storage, is proposed. Control accuracy of 0.012 μL per pulse is obtained and a theoretical service life of more than 20 years can be achieved. The whole active lubricating system is embedded in the bearing system, which has no effect on the normal operating of the original bearing system and almost creates no mass increment of the bearing system. The methods of controlling the characteristics of the ejected oil droplet are proposed to meet different lubrication requirements. Combined with the monitoring of bearing temperature and friction torque, active lubrication on demand can be realized. This work can provide important references for prolonging the service life of space bearing. [ABSTRACT FROM AUTHOR]

Collective cell migration (CCM) is a universal process that is responsible for various biological phenomena in living organisms. Therefore, unraveling the mechanism of CCM is critical for understanding the principles underlying such processes and for their application in biomaterials and biomedical science. Among these phenomena, unjamming/jamming transitions are particularly intriguing as they are controlled by three factors: cell motility, cell density, and cell–cell adhesion. However, there is no experimental system to independently demonstrate and control these effects. In this study, we added 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) to a nitrobenzene droplet containing KI and I2 to develop a prototype system that shows self-propelled motion in an aqueous trimethylstearylammonium chloride (TSAC) solution. First, we explored the relationship between the motility of the droplet and experimental parameters, namely, the concentrations of TSAC, I2, and DMPC and droplet size. The droplet showed directional motion driven by Marangoni convection owing to a solubilization promoted by the formation of mixed micelles filled with oil between DMPC and TSA+; notably, droplet motility could be controlled by each parameter. Furthermore, the interfacial tension (γ) at the oil–water interface, measured using the pendant drop method, indicated that each parameter contributed to changes in γ. Based on our experimental results, we inferred that the dynamics of the insertion of TSA+ in the aqueous phase into the self-assembled DMPC membrane covering the nitrobenzene droplet, as well as the solubilization, are important factors that trigger Marangoni convection and lead to controlled droplet motility. Furthermore, the developed droplets remained stable in a confluent state, wherein they were in contact with each other and exhibited various polygonal shapes depending on their size and density because they were protected by a robust self-assembled DMPC membrane layer. The results indicated that the density and the morphology of the droplets are controllable in this system, and that they indirectly altered droplet adhesion. Thus, we procured a prototype system that could be controlled independently using three parameters to elucidate phase transition for CCM. This system can be biomodified through the combination of phospholipids with any biomolecule and can enable a more precise evaluation of the CCM exhibited by living cells.

Key message: Hereby, we present a rare case of a resected endobronchial tumour that floated or showed oil droplets in saline. In this study, we report an interesting image related to endobronchial lipomatous hamartoma cryotherapy. [ABSTRACT FROM AUTHOR]

Previous studies have been carried out on the effect of silica nanoparticles (SNPs) on the stability of oil–water emulsions. However, the combining configuration of SNPs and oil droplets at the molecular level and the effect of SNP content on the coalescence behavior of oil droplets cannot be obtained through experiments. In this paper, molecular dynamics (MD) simulation was performed to investigate the adsorption configuration of hydrophilic SNPs in an O/W emulsion system, and the effect of adsorption of SNPs on coalescence of oil droplets. The simulation results showed: (i) SNPs adsorbed on the surface of oil droplets, and excessive SNPs self-aggregated and connected by hydrogen bonds. (ii) Partially hydrophilic asphaltene and resin molecules formed adsorption configurations with SNPs, which changed the distribution of oil droplet components. Furthermore, compared with hydrophobic asphaltene, the hydrophilic asphaltene was easier to combine with SNPs. (iii) SNPs would extend the oil droplet coalescence time, and the π–π stacking structures were formed between asphaltene and asphaltene or resin molecules to enhance the connection between oil droplets during the oil droplet contact process. (iv) Enough SNPs tightly wrapped around the oil droplet, similar to the formation of a rigid film on the surface of an oil droplet, which hindered the contact and coalescence of components between oil droplets.

• Systematic study of the rising motion of oil droplets in natural waters. • Discovered that oil droplet properties affect the rising motion process. • Modeling the terminal velocity of oil droplets in natural waters. • Modeling the drag coefficient of oil droplets in natural waters. This work focuses on investigating the dynamics of different types of oil droplets rising freely in water columns. Fifteen different types of oils were selected to cover most of the conventional oils. The particle size range of the study is 1.41∼13.58 mm, which can cover the largest oil droplet size that may occur in the real environment. Investigation results show that oil droplet characteristics greatly influence the dynamics process of oil droplet motion. The characteristics which play a dominant role will change as the oil droplet particle size increases. Meanwhile, a set of computational models applicable to the terminal velocity and drag coefficient of oil droplets in the range of 20 < Re < 1200 in a non-pure system are obtained by organizing the experimental data and comparing with the traditional correlation equation, respectively. The models involve dimensionless parameters such as Eo, Mo, and We numbers with fitting coefficients up to 0.984. [ABSTRACT FROM AUTHOR]

Abstract Background The essential oil is an important compound of the root and rhizome of medicinally used valerian (Valeriana officinalis L. s.l.), with a stated minimum content in the European pharmacopoeia. The essential oil is located in droplets, of which the position and distribution in the total root cross-section of different valerian varieties, root thicknesses and root horizons are determined in this study using an adapted fluorescence-microscopy and automatic imaging analysis method. The study was initiated by the following facts:A probable negative correlation between essential oil content and root thickness in selected single plants (elites), observed during the breeding of coarsely rooted valerian with high oil content.Higher essential oil content after careful hand-harvest and processing of the roots. Results In preliminary tests, the existence of oil containing droplets in the outer and inner regions of the valerian roots was confirmed by histological techniques and light-microscopy, as well as Fourier-transform infrared spectroscopy. Based on this, fluorescence-microscopy followed by image analysis of entire root cross-sections, showed that a large number of oil droplets (on average 43% of total oil droplets) are located close to the root surface. The remaining oil droplets are located in the inner regions (parenchyma) and showed varying density gradients from the inner to the outer regions depending on genotype, root thickness and harvesting depth. Conclusions Fluorescence-microscopy is suitable to evaluate prevalence and distribution of essential oil droplets of valerian in entire root cross-sections. The oil droplet density gradient varies among genotypes. Genotypes with a linear rather than an exponential increase of oil droplet density from the inner to the outer parenchyma can be chosen for better stability during post-harvest processing. The negative correlation of essential oil content and root thickness as observed in our breeding material can be counteracted through a selection towards generally high oil droplet density levels, and large oil droplet sizes independent of root thickness.

A coalescer is a useful device for removing oil from oil-in-water (O/W) emulsion, but it is unsuitable for the coalescence of fine oil droplets less than 10 pm. In this study, a nanofiber membrane was applied as a fibrous layer equipped in the coalescer to coalesce the fine oil droplets less than 10 pm, and the lipophilic polypropylene nanofiber membrane was selected in consideration of an affinity for oil. The O/W emulsion including the fine oil droplets was permeated through the membrane for evaluating the coalescence properties of fine oil droplets. In the initial stage of permeation, the oil droplets were strongly attracted to the lipophilic surface of nanofibers, and a thin oil film was formed on the entire fiber surface. Subsequent oil droplets were incorporated into the oil film, resulting in the growth of the oil film. When the fibers could no longer hold fully grown oil film, excess oil film was finally released from the outlet of the membrane. The released oil pieces floated and formed an oil layer on the surface of permeated fluid. In the steady state, the separation ratio of 83.3 % was observed under low pressure loss of 17 kPa. The size distribution data of droplets in the permeated fluid clearly demonstrated that the polypropylene nanofiber membrane used in this study could completely coalesce and separate the fine oil droplets of 2 to 10 gni. [ABSTRACT FROM AUTHOR]

Abstract Background The unicellular green alga, Chlamydomonas reinhardtii, is a classic model for studying flagella and biofuel. However, precise gene editing, such as Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and CRISPR-associated protein (Cas9) system, is not widely used in this organism. Screening of random insertional mutant libraries by polymerase chain reaction provides an alternate strategy to obtain null mutants of individual gene. But building, screening, and maintaining such a library was time-consuming and expensive. Results By selecting a suitable parental strain, keeping individual mutants using the agar plate, and designing an insertion cassette-specific primer for library screening, we successfully generated and maintained ~150,000 insertional mutants of Chlamydomonas, which was used for both reverse and forward genetics analysis. We obtained 26 individual mutants corresponding to 20 genes and identified 967 motility-defect mutants including 10 mutants with defective accumulation of intraflagellar transport complex at the basal body. We also obtained 929 mutants defective in oil droplet assembly after nitrogen deprivation. Furthermore, a new insertion cassette with splicing donor sequences at both ends was also constructed, which increased the efficiency of gene interruption. Conclusion In summary, this library provides a multifunctional platform both for obtaining mutants of interested genes and for screening of mutants with specific phenotype.

Highlights • The interactions between an oil droplet and a horizontal solid surface was analyzed. • There is a separation distance between an oil droplet and a solid surface. • The droplet and solid surface zeta potentials affect the droplet moving direction. • The droplet moving velocity increases with the decrease of the separation distance. Abstract This work numerically investigated the translational velocity of a negatively charged oil droplet in the water near a negatively charged solid surface under a DC electric field. The equilibrium separation distance between the charged oil droplet and the charged solid surface is calculated under different parameters and the translational motion of the droplet near the solid surface is simulated via a three-dimensional mathematical model. The results indicate that the velocity of the droplet is higher under a larger zeta potential of the solid surface and a smaller zeta potential of the droplet. When the absolute value of the negative zeta potential of the droplet is larger than that of the solid surface, the droplet will move in opposite direction of the electric field. It is also found that the droplet translational velocity increases with the decrease of the separation distance between the oil droplet and the solid surface. [ABSTRACT FROM AUTHOR]

Abstract Oil–air lubrication supplies lubricants in the form of droplets to elastohydrodynamic lubrication (EHL) contacts, such as those in high-speed spindle bearings. However, there is a paucity of information related to understanding the lubrication behaviors of oil droplets within EHL contacts. In this study, behaviors of lubricant droplets, in terms of spreading around a static contact as well as passing through a rolling contact, were studied with an optical ball-on-disk EHL test rig. Influences of oil droplet size, viscosity, and surface tension on droplet spreading were examined. Lubricating film formation was also investigated when droplets traveled through the EHL contact region. The results indicated that droplet size and running speed significantly influenced film profiles. With increasing entrainment speeds, a small droplet passed through the contact without spreading and generated films with a significant depression in the central contact region.

A modified computational fluid dynamic (CFD) model has been developed to obtain oil removal efficiency for oily wastewater treatment in large-scale flotation tanks. According to the investigation of oil droplet/bubble interactions in a flotation tank, a modified Bloom−Heindel model is used to calculate the collision and attachment efficiencies between oil droplets and bubbles. Effects of the gas flow rate, oil diameter and oil concentration on oil removal efficiency of flotation tank were analyzed experimentally. The application scope of this modified CFD model is evaluated using experimental results. In addition, the comparison between the existing model and the modified model demonstrates that this modified CFD model can make a good prediction for the separation performance of the flotation tank.

Highlights • There is a separation distance between an oil droplet and an air–water interface. • A negatively charged interface moves in opposite direction of the DC electric field. • The effect of the mobile air–water interface on the droplet velocity was analyzed. • This moving oil droplet surface and the inner flow affect the droplet velocity. Abstract A numerical study on the electrokinetic motion of a charged oil droplet near a charged air–water interface is presented in this paper. First, the separation distance between the oil droplet and the air–water interface is calculated, and then the electrokinetic velocity of the droplet is simulated utilizing a three-dimensional numerical model under different applied electric fields, droplet’s radii, ionic concentrations, zeta potentials of the oil–water interface, and zeta potentials of the air–water interface. The numerical results indicate that a negatively charged oil droplet near a negatively charged air–water interface moves in opposite direction of the direct current electric field and has larger velocity under higher electric field strength, droplet’s radius, ionic concentration, and absolute values of the two interface zeta potentials. [ABSTRACT FROM AUTHOR]

In recent years, significant progress has been achieved in the study of aqueous foams. Having said this, a better understanding of foam physics requires a deeper and profound study of foam elements. This paper reviews the studies in the microscale of aqueous foams. The elements of aqueous foams are interior Plateau borders, exterior Plateau borders, nodes, and films. Furthermore, these elements' contribution to the drainage of foam and hydraulic resistance are studied. The Marangoni phenomena that can happen in aqueous foams are listed as Marangoni recirculation in the transition region, Marangoni-driven flow from Plateau border towards the film in the foam fractionation process, and Marangoni flow caused by exposure of foam containing photosurfactants under UV. Then, the flow analysis of combined elements of foam such as PB-film along with Marangoni flow and PB-node are studied. Next, we contrast the behavior of foams in different conditions. These various conditions can be perturbation in the foam structure caused by injected water droplets or waves or using a non-Newtonian fluid to make the foam. Further review is about the effect of oil droplets and particles on the characteristics of foam such as drainage, stability and interfacial mobility. [ABSTRACT FROM AUTHOR]

Multi-oil droplet target recognition is one of the applications of machine vision in the measurement of oil-water two-phase flow parameters , which could combine other algorithms to obtain the oil droplet velocity and the water holdup of oil water two-phase flow. Appropriate target representation features can improve the recognition effect of multiple oil droplets. However, due to shooting environment differences and quality differences of oil-water two-phase flow images, existing target representation features do not perform well in low-quality oil-water two-phase flow images. To improve the precision of multi-oil droplet target recognition in oil-water two-phase flow and reduce the miss rate, this paper constructs an integrated feature on the basis of aggregate channel features (ACF). The integrated feature named aggregate channel features with histogram of local gravitational feature（ACFHG） contains the color feature channels reflecting the overall color features of the oil droplet sample, the gradient amplitude channel reflecting the overall gradient of the oil droplet sample image, the gradient direction histogram feature channels reflecting the local gradient of the oil droplet sample image, and the local gravitational feature channels that ensure oil droplet target recognition in low quality photos and photos taken in complex shooting environments. Moreover, the rotation invariance is obtained by taking the oriented gradient histogram of the local gravitational feature to further improve the multi-oil droplet target recognition effect. Experiment results show that the average precision of multi-oil droplet target recognition using the integrated features is 83.38%, which is 9.93% higher than that with using ACF, and the miss rate is 9.13%, which is 57.18% lower than that with using ACF. Compared with other existing target detection methods, the method proposed in this paper still has an advantage in the rate of missed detection. • Integrated features for improving the precision and reducing the miss rate in the multi-oil droplet recognition process are proposed. • The average precision of using integrated feature is 9.93% higher than that of using aggregate channel features. • The miss rate of using integrated feature is 57.18% lower than that of using aggregate channel features. [ABSTRACT FROM AUTHOR]