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1
Xing, Lei, Jinyu Li, Minghu Jiang i Lixin Zhao. "Dynamic behavior of compound droplets with millimeter-sized particles impacting substrates with different wettabilities". Physics of Fluids 35, nr 2 (luty 2023): 022108. http://dx.doi.org/10.1063/5.0137505.
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The dynamic behavior of compound droplets, which are made up of a millimeter-sized particle and distilled water, impacting substrates of different wettabilities is investigated via high-speed photography. The effects of the size of the particle within the compound droplet, substrate contact angle, and impact height on the deformation of the droplets and the characteristics of the impact are analyzed. It is found that the collisions of compound droplets with substrates can be classified into four categories based on the observed experimental phenomena that occur during the impact. These categories are referred to as adhesion collision, rebound collision, daughter-droplet collision (or partial rebound collision), and breakup collision. We consider both the impact of water droplets and compound droplets (with one of two different-sized particles) on substrates of different wettabilities. The effects of inertia, surface tension, and adhesion between the substrate and the liquid droplet, and adhesion between the particle and the liquid droplet are considered to explain the different collision phenomena of compound droplets and reveal the evolution mechanism of the droplet morphologies in the experiments. Furthermore, the effects of the height from which the droplet is released and the contact angle of the substrate (i.e., its wettability) on the maximum spreading diameter and maximum jet height of the droplet are presented quantitatively. The effect of the size of the particle within the compound droplet and the substrate contact angle on the dynamic behavior of the compound droplet subject to impact with the substrate is also described.
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Nguyen, Khanh P., i Truong V. Vu. "Collision Modes of Two Eccentric Compound Droplets". Processes 8, nr 5 (18.05.2020): 602. http://dx.doi.org/10.3390/pr8050602.
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A compound droplet with its single inner droplet appears in a broad range of applications and has received much attention in recent years. However, the role of the inner droplet location on the dynamical behaviors of the compound droplet is still not completely understood. Accordingly, the present study numerically deals with the eccentricity of the compound droplet affecting its colliding behaviors with the other droplet in a simple shear flow. The solving method is a front-tracking technique that treats the droplet interface as connected elements moving on a rectangular fixed grid. Initially, two compound droplets assumed circular are placed at a distance symmetrically to the domain center and they come into contact, because of the shear flow, when time progresses. During the collision process, the inner droplet that is initially located at a distance to its outer droplet center circulates around this center. It is found that this rotation also contributes to the formation of the collision modes including the reversing, passing-over and merging ones. Starting from a passing-over mode, a transition to a reversing mode or a merging mode can appear when the inner droplets, in terms of their centroids, are closer than their outer droplets. However, the location of the inner droplet within the outer droplet only has an effect when the value of the Capillary number Ca is varied from 0.01 to 0.08. For Ca < 0.01 corresponding to the merging mode and Ca ≥ 0.16 corresponding to the passing-over mode, the inner droplet position has almost no impact on the collision behaviors of two compound droplets.
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Pronkina, Tatiana Vasilievna. "About the influence of the forces of interaction between the droplets on the dynamics of emulsion". Yugra State University Bulletin 15, nr 1 (9.12.2019): 59–65. http://dx.doi.org/10.17816/byusu20190159-65.
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The dynamics of deposition of compound droplets of the emulsion under the action of gravity is investigated. The interaction of the droplet with its inclusion is taken into account. Axisymmetric and asymmetric problems of deposition of compound droplets are considered. Expressions for the relative and absolute velocities of the compound emulsion droplets are found. Based on numerical modeling, the trajectories of the relative and absolute motion of the droplets are obtained.
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Sun, Meimei, Miao Zhao i Wei Gao. "Hydrodynamics of Compound Droplet Flowing in the Curved Minichannel". Advances in Condensed Matter Physics 2019 (15.10.2019): 1–11. http://dx.doi.org/10.1155/2019/5726974.
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Based on the volume of fluid (VOF) method, a theoretical model of compound droplet deformation in curved minichannel is developed. The effects of curved angle, continuous phase, radius ratio between the inner and integral droplets, and viscosity of the middle phase are examined to reveal the underlying mechanism of compound droplet deformation. The results indicate that the deformation process of the compound droplets in the curved minichannel can be divided into three stages, namely, the initial stage, the turning stage, and the adjustment stage. Both large curved angle and high capillary number of the continuous phase result in the large shear force and high eccentricity of the compound droplet. However, as the radius ratio increases, the influence of the inner droplet on the deformation of the compound droplet transits from enhancing to suppressing.
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Xue, Xinzhi, i Joseph Katz. "Formation of compound droplets during fragmentation of turbulent buoyant oil jet in water". Journal of Fluid Mechanics 878 (4.09.2019): 98–112. http://dx.doi.org/10.1017/jfm.2019.645.
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Fragmentation of a vertical buoyant silicone oil jet injected into sugar water is elucidated by refractive index matching and planar laser-induced fluorescence. Compound droplets containing multiple water droplets, some with smaller oil droplets, form regularly at jet Reynolds numbers of $Re=1358$ and 2122 and persist for at least up to 30 nozzle diameters. In contrast, they rarely appear at $Re=594$. The origin of some of the encapsulated water droplets can be traced back to the entrained water ligaments during the initial roll-up of Kelvin–Helmholtz vortices. Analysis using random forest-based procedures shows that the fraction of compound droplets does not vary significantly with $Re$, but increases rapidly with droplet diameter, reaching 78 % for 2 mm droplets. Consequently, the size distributions of compound droplets have peaks that increase in magnitude and shift to a lower diameter with increasing $Re$. On average, the interior pockets raise the oil–water interfacial area by 15 %, increasing with diameter and axial location. Also, while the oil droplets are deformed by the jet’s shear field, the interior interfaces remain nearly spherical, consistent with prior studies of the deformation of isolated compound droplets for relevant capillary numbers and viscosity ratio.
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Ma, Zeyao, Shuai Zhang, Bo Wang, Qingquan Liu i Xiaodong Chen. "Deformation characteristics of compound droplets with different morphologies during transport in a microchannel". Physics of Fluids 35, nr 4 (kwiecień 2023): 042003. http://dx.doi.org/10.1063/5.0146560.
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A numerical investigation of the deformation of compound microdroplets transported inside a circular microchannel is described in this article. Two droplet morphologies are considered (shell-core and Janus), which correspond to nonequilibrium and equilibrium states, respectively, based on the balancing of the three interfacial tensions at the triple line. Numerical simulations coupled with a three-phase volume-of-fluid method are performed on axisymmetric models to consider both the absence and presence of a triple line. In addition to adaptive mesh refinement on the interfaces, topology-oriented refinement is used to resolve thin films between the shell and core droplets. After experimental validation, the effects of flow rates, physical properties, and confinement conditions are considered. In the reference frame of the droplets, there are five inner vortexes inside the shell-core droplet, while only three are present inside the Janus droplet, the same as single-phase droplets. For shell-core droplets, the aspect ratio of the shell droplet decreases with the capillary number of the continuous phase and droplet sizes, while sudden jumps are identified when the thin film forms between the shell and core interfaces. Conversely, the aspect ratio of the core droplet increases and then decreases when the shape of the core droplets is influenced by the flow and space confinements. With Janus droplets, the aspect ratio decreases with the capillary number. The axial length of the front portion decreases with the capillary number and then reaches a plateau with small variations, while that of the rear portion increases nearly linearly.
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Suzuki, Toyoko, Yunfeng Li, Albert Gevorkian i Eugenia Kumacheva. "Compound droplets derived from a cholesteric suspension of cellulose nanocrystals". Soft Matter 14, nr 47 (2018): 9713–19. http://dx.doi.org/10.1039/c8sm01716f.
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Compound Janus droplets were generated using microfluidic emulsification of the cholesteric suspension of cellulose nanocrystals and mineral oil. The capability to fine-tune droplet composition and the shape of the cholesteric phase is shown. The droplets were used to generate cholesteric microgels with non-conventional shapes.
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Ghaznavi, Amirreza, Yang Lin, Mark Douvidzon, Adam Szmelter, Alannah Rodrigues, Malik Blackman, David Eddington i in. "A Monolithic 3D Printed Axisymmetric Co-Flow Single and Compound Emulsion Generator". Micromachines 13, nr 2 (26.01.2022): 188. http://dx.doi.org/10.3390/mi13020188.
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We report a microfluidic droplet generator which can produce single and compound droplets using a 3D axisymmetric co-flow structure. The design considered for the fabrication of the device integrated a user-friendly and cost-effective 3D printing process. To verify the performance of the device, single and compound emulsions of deionized water and mineral oil were generated and their features such as size, generation frequency, and emulsion structures were successfully characterized. In addition, the generation of bio emulsions such as alginate and collagen aqueous droplets in mineral oil was demonstrated in this study. Overall, the monolithic 3D printed axisymmetric droplet generator could offer any user an accessible and easy-to-utilize device for the generation of single and compound emulsions.
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Weyer, Floriane, Marouen Ben Said, Johannes Hötzer, Marco Berghoff, Laurent Dreesen, Britta Nestler i Nicolas Vandewalle. "Compound Droplets on Fibers". Langmuir 31, nr 28 (8.07.2015): 7799–805. http://dx.doi.org/10.1021/acs.langmuir.5b01391.
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Ruehl, C. R., P. Y. Chuang i A. Nenes. "Aerosol hygroscopicity at high (99 to 100%) relative humidities". Atmospheric Chemistry and Physics Discussions 9, nr 4 (24.07.2009): 15595–640. http://dx.doi.org/10.5194/acpd-9-15595-2009.
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Abstract. The hygroscopicity of an aerosol largely determines its influence on climate and, for smaller particles, atmospheric lifetime. While much aerosol hygroscopicity data is available at lower relative humidities (RH) and under cloud formation conditions (RH>100%), relatively little data is available at high RH (99.2 to 99.9%). We measured the size of droplets at high RH that had formed on particles composed of one of seven compounds with dry diameters between 0.1 and 0.5 μm, and calculated the hygroscopicity of these compounds. We use a parameterization of the Kelvin term, in addition to a standard parameterization (κ) of the Raoult term, to express the hygroscopicity of surface-active compounds. For inorganic compounds, hygroscopicity could reliably be predicted using water activity data and assuming a surface tension of pure water. In contrast, most organics exhibited a slight to mild increase in hygroscopicity with droplet diameter. This trend was strongest for sodium dodecyl sulfate (SDS), the most surface-active compound studied. The results suggest that partitioning of surface-active compounds away from the bulk solution, which reduces hygroscopicity, dominates any increases in hygroscopicity due to reduced surface tension. This is opposite to what is typically assumed for soluble surfactants. Furthermore, we saw no evidence that micellization limits SDS activity in micron-sized solution droplets, as observed in macroscopic solutions. These results suggest that while the high-RH hygroscopicity of inorganic compounds can be reliably predicted using readily available data, surface-activity parameters obtained from macroscopic solutions with organic solutes may be inappropriate for calculations of the hygroscopicity of micron-sized droplets.
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Henkel, Thomas, Günter Mayer, Jörg Hampl, Jialan Cao, Linda Ehrhardt, Andreas Schober i Gregor Alexander Groß. "From Microtiter Plates to Droplets—There and Back Again". Micromachines 13, nr 7 (28.06.2022): 1022. http://dx.doi.org/10.3390/mi13071022.
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Droplet-based microfluidic screening techniques can benefit from interfacing established microtiter plate-based screening and sample management workflows. Interfacing tools are required both for loading preconfigured microtiter-plate (MTP)-based sample collections into droplets and for dispensing the used droplets samples back into MTPs for subsequent storage or further processing. Here, we present a collection of Digital Microfluidic Pipetting Tips (DMPTs) with integrated facilities for droplet generation and manipulation together with a robotic system for its operation. This combination serves as a bidirectional sampling interface for sample transfer from wells into droplets (w2d) and vice versa droplets into wells (d2w). The DMPT were designed to fit into 96-deep-well MTPs and prepared from glass by means of microsystems technology. The aspirated samples are converted into the channel-confined droplets’ sequences separated by an immiscible carrier medium. To comply with the demands of dose-response assays, up to three additional assay compound solutions can be added to the sample droplets. To enable different procedural assay protocols, four different DMPT variants were made. In this way, droplet series with gradually changing composition can be generated for, e.g., 2D screening purposes. The developed DMPT and their common fluidic connector are described here. To handle the opposite transfer d2w, a robotic transfer system was set up and is described briefly.
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Peng, Feng, Zhaohui Wang, Yiwei Fan, Qianwen Yang i Jie Chen. "Study on the interfacial dynamics of free oscillatory deformation and breakup of single-core compound droplet". Physics of Fluids 34, nr 4 (kwiecień 2022): 042009. http://dx.doi.org/10.1063/5.0087738.
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Compound droplets are usually taken as microcontainers for biomedical and material encapsulation applications in which a good understanding of the free oscillatory deformation and breakup behavior is essential. In this work, the dynamics of free oscillatory deformation and breakup of a single-core compound droplet with an initial ellipsoidal shell was investigated numerically using the volume-of-fluid method. The effects of droplet diameter and the outer droplet initial deformation parameter are considered. Four outcomes are identified: oscillatory deformation, separation, separation breakup, and breakup. The evolution of the kinetic energy and pressure field of the compound droplet for the four typical outcomes is also analyzed in detail. A clear boundary exists between the first and the latter three outcomes (initial deformation parameters of 0.600–0.773), while the critical factor for the latter three outcomes is the inner and outer droplet diameter ratio. The oscillatory deformation is characterized by the inner and outer droplet undergoing a finite deformation and subsequent oscillatory behavior, with the maximum deformation of the inner and outer droplets being related to the energy transfer between the two, and the outer droplet being a periodic decaying oscillation, while the inner droplet is a large deformation oscillation interspersed with a small deformation oscillation. Separation, separation breakup, and breakup are characterized by breakup at the inner or outer interface during deformation; separation and breakup times are largely dependent on droplet diameter and the initial deformation parameter of the outer droplet; and the neck width at separation is also analyzed in detail.
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Nagelberg, Sara, Amy Goodling, Kaushikaram Subramanian, George Barbastathis, Moritz Kreysing, Tim Swager, Lauren Zarzar i Mathias Kolle. "Bi-phase emulsion droplets as dynamic fluid optical systems". EPJ Web of Conferences 215 (2019): 13003. http://dx.doi.org/10.1051/epjconf/201921513003.
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Micro-scale optical components play a critical role in many applications, in particular when these components are capable of dynamically responding to different stimuli with a controlled variation of their optical behavior. Here, we discuss the potential of micro-scale bi-phase emulsion droplets as a material platform for dynamic fluid optical components. Such droplets act as liquid compound micro-lenses with dynamically tunable focal lengths. They can be reconfigured to focus or scatter light and form images. In addition, we discuss how these droplets can be used to create iridescent structural color with large angular spectral separation. Experimental demonstrations of the emulsion droplet optics are complemented by theoretical analysis and wave-optical modelling. Finally, we provide evidence of the droplets utility as fluidic optical elements in potential application scenarios.
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Eriksson, Hans, Johan Brengdahl, Petter Sandström, Mattias Rohman i Bruno Becker. "Validation of Low-Volume 1536-Well Assay-Ready Compound Plates". Journal of Biomolecular Screening 14, nr 5 (21.05.2009): 468–75. http://dx.doi.org/10.1177/1087057109335324.
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Assay-ready compound plates (ARPs) are sealed assay plates that contain DMSO solutions of screening compounds predispensed for particular assays. Assays are started by adding assay buffer and reagents to the ARPs. This concept offers important logistical advantages for screening such as decoupling of the plate preparation from the screening process and exchange of assay plates between different geographical locations. Compound solutions can be accurately and precisely dispensed by acoustic droplet ejection technology in the small volumes required for screening in the 1536-well format. At such low volumes, however, potential effects such as solvent evaporation, compound degradation, precipitation, or adsorption are reasons for concern with regard to assay reproducibility, performance, and shelf life of ARPs. To address these concerns, the authors screened freshly prepared ARPs using several types of assays. The results were compared to results obtained from plates stored for up to 13 days under 2 storage conditions (22 °C, —18 °C). Tight correlations between results were found that indicated that temperature and time had very little influence on the assay performance for up to about 1 week storage time of the plates. In addition, using a time series of microphotographs of DMSO droplets, the authors visually confirmed that the sizes of the droplets in ARPs apparently do not change over 13 days under certain storage conditions.
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Gao, Sheng Dong, Yang Wang, Yan Wu i Zhi Wei Liu. "Experimental Study on Factors of Jet Breakup for Uniform Droplet Stream". Applied Mechanics and Materials 101-102 (wrzesień 2011): 1027–30. http://dx.doi.org/10.4028/www.scientific.net/amm.101-102.1027.
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In this study an experimental device capable of producing uniform metal droplet stream with image gathering was set up. A periodic vibration was applied to a compound liquid jet for an experimental study on its breakup. The breakup processes of the compound jet were discussed from the image taken from the experiment. The aim is to study the relationship of the factors which determine the jet breakup into a series of uniform droplets.
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Chen, R. H., i C.-M. Lai. "Collision outcome of a water drop on the surface of a deep diesel fuel pool". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 225, nr 7 (11.05.2011): 1638–48. http://dx.doi.org/10.1177/0954406211403066.
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This study investigated the collision of water drops with diesel fuel. The target liquid was selected not only because this interaction is commonly observed in many fires but also because diesel fuel exhibits similar viscosity to heavy oils on fire. Investigated collision phenomena include water drop disintegration, cavity development, droplet ejection from the underside of the cavity, droplet ejection from the liquid (diesel fuel) crown rim, and formation of water-in-diesel compound drops. Results suggest that the number of water droplets from the disintegrated water drop increases non-linearly with increased Weber number. At a Weber number of 700, the number of water droplets reached a maximum while their size was minimized.
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Ruehl, C. R., P. Y. Chuang i A. Nenes. "Aerosol hygroscopicity at high (99 to 100%) relative humidities". Atmospheric Chemistry and Physics 10, nr 3 (5.02.2010): 1329–44. http://dx.doi.org/10.5194/acp-10-1329-2010.
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Abstract. The hygroscopicity of an aerosol strongly influences its effects on climate and, for smaller particles, atmospheric lifetime. While many aerosol hygroscopicity measurements have been made at lower relative humidities (RH) and under cloud formation conditions (RH>100%), relatively few have been made at high RH (99 to 100%), where the Kelvin (curvature) effect is comparable to the Raoult (solute) effect. We measured the size of droplets at high RH that had formed on particles composed of one of seven compounds with dry diameters between 0.1 and 0.5 μm. We report the hygroscopicity of these compounds using a parameterization of the Kelvin term, in addition to a standard parameterization (κ) of the Raoult term. For inorganic compounds, hygroscopicity could reliably be predicted using water activity data (measured in macroscopic solutions) and assuming a surface tension of pure water. In contrast, most organics exhibited a slight to mild increase in hygroscopicity with droplet diameter. This trend was strongest for sodium dodecyl sulfate (SDS), the most surface-active compound studied. The results suggest that, for single-component aerosols at high RH, partitioning of solute to the particle-air interface reduces particle hygroscopicity by reducing the bulk solute concentration. This partitioning effect is more important than the increase in hygroscopicity due to surface tension reduction. Furthermore, we found no evidence that micellization limits SDS activity in micron-sized solution droplets, as observed in macroscopic solutions. We conclude that while the high-RH hygroscopicity of inorganic compounds can be reliably predicted using readily available data, surface-activity parameters obtained from macroscopic solutions with organic solutes may be inappropriate for calculations involving micron-sized droplets.
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Zhou, Ronghong, Sheng Li, Liang Shi, Ningning Wang, Yong Liu i Haihu Liu. "Modeling and simulation of the penetration of a compound droplet into a throat in a pore-throat structure". Physics of Fluids 35, nr 2 (luty 2023): 023328. http://dx.doi.org/10.1063/5.0134587.
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We present a theoretical and numerical study of a compound droplet flowing through a single pore-throat structure. By quantifying the capillary pressures in the pore and throat under various geometrical conditions, we derive a theoretical model to predict whether the compound droplet is able to penetrate into the throat in a pore-throat structure. Meanwhile, the lattice Boltzmann simulations are conducted to assess the capability and accuracy of the theoretical model. Through a combination of theoretical analysis and lattice Boltzmann simulations, we then investigate the effect of inner droplet size, compound droplet size, and surface wettability on the invasion behavior of a compound droplet. The results show that with increasing the inner droplet size or the compound droplet size, the compound droplet undergoes the transition from the state where the entire compound droplet can pass through the throat to the state where only a part of outer droplet penetrates into and blocks the throat. Although the theoretical predictions show good agreement with the simulation results for most of the cases investigated, it is found that the proposed theoretical model is not applicable to the cases in which the droplets are intermediate-wetting or wetting to the solid surface. This is because the shape of newly formed interface in the pore significantly deviates from the initial circle, which violates the assumption made in the derivation of the theoretical model.
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Han, Xiaotian, Hua Zhou, Yifei Zhu, Liangyu Wu, Feng Yao i Cheng Yu. "Improvement of the Sphericity and the Thickness Uniformity of the Polystyrene (PS) Shell Microsphere during Curing Process". Coatings 9, nr 6 (14.06.2019): 385. http://dx.doi.org/10.3390/coatings9060385.
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To improve the quality of dispersed polystyrene (PS) compound droplets, a new random rotating curing system is designed. In addition, the qualities of the curing products of the PS compound droplets of this new system are compared with those of the traditional curing system with a constant rotating speed, so as to verify the effectiveness of the new system on the quality improvement of the PS compound droplets. The effect of the liquid level, rotation rate and the density difference on the curing process is also analyzed to reveal the mechanism of the curing process in a rotating flow field. The results indicate that, in the new rotating curing system, the disturbance of the fluid increases the deformation recovery ability of the compound droplets. Furthermore, the vortex with different directions in the external flow fields, make the compound droplets spin in many directions, which improves the spheroidization and concentricity of the compound droplets. Compared with using the traditional rotating curing system, when utilizing the random rotating curing system, the sensitivity of the microspheres’ quality to the density mismatch between the phases is smaller, and the sphericity and the thickness uniformity of the polystyrene (PS) microsphere increase by 10.2% and 4.5%, respectively. In addition, there is an optimal rotation rate for the random rotating curing device, which can optimize the survival rate and quality of the hollow microspheres.
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MAHADEVAN, L., M. ADDA-BEDIA i Y. POMEAU. "Four-phase merging in sessile compound drops". Journal of Fluid Mechanics 451 (25.01.2002): 411–20. http://dx.doi.org/10.1017/s0022112001007108.
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We consider the statics of compound droplets made of two immiscible fluids on a rigid substrate, in the limit when gravity is dominated by capillarity. In particular, we show that the merging of four phases along a single contact line is a persistent and robust phenomenon from a mechanical and thermodynamic perspective; it can and does occur for a range of interfacial energies and droplet volumes. We give an interpretation for this in the context of the macroscopic Young–Laplace law and its microscopic counterpart due to van der Waals, and show that the topological transitions that result can be of either a continuous or discontinuous type depending on the interfacial energies in question.
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Chim, Man Mei, Chiu Tung Cheng, James F. Davies, Thomas Berkemeier, Manabu Shiraiwa, Andreas Zuend i Man Nin Chan. "Compositional evolution of particle-phase reaction products and water in the heterogeneous OH oxidation of model aqueous organic aerosols". Atmospheric Chemistry and Physics 17, nr 23 (5.12.2017): 14415–31. http://dx.doi.org/10.5194/acp-17-14415-2017.
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Abstract. Organic compounds present at or near the surface of aqueous droplets can be efficiently oxidized by gas-phase OH radicals, which alter the molecular distribution of the reaction products within the droplet. A change in aerosol composition affects the hygroscopicity and leads to a concomitant response in the equilibrium amount of particle-phase water. The variation in the aerosol water content affects the aerosol size and physicochemical properties, which in turn governs the oxidation kinetics and chemistry. To attain better knowledge of the compositional evolution of aqueous organic droplets during oxidation, this work investigates the heterogeneous OH-radical-initiated oxidation of aqueous methylsuccinic acid (C5H8O4) droplets, a model compound for small branched dicarboxylic acids found in atmospheric aerosols, at a high relative humidity of 85 % through experimental and modeling approaches. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (Direct Analysis in Real Time, DART) coupled with a high-resolution mass spectrometer reveal two major products: a five carbon atom (C5) hydroxyl functionalization product (C5H8O5) and a C4 fragmentation product (C4H6O3). These two products likely originate from the formation and subsequent reactions (intermolecular hydrogen abstraction and carbon–carbon bond scission) of tertiary alkoxy radicals resulting from the OH abstraction occurring at the methyl-substituted carbon site. Based on the identification of the reaction products, a kinetic model of oxidation (a two-product model) coupled with the Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients (AIOMFAC) model is built to simulate the size and compositional changes of aqueous methylsuccinic acid droplets during oxidation. Model results show that at the maximum OH exposure, the droplets become slightly more hygroscopic after oxidation, as the mass fraction of water is predicted to increase from 0.362 to 0.424; however, the diameter of the droplets decreases by 6.1 %. This can be attributed to the formation of volatile fragmentation products that partition to the gas phase, leading to a net loss of organic species and associated particle-phase water, and thus a smaller droplet size. Overall, fragmentation and volatilization processes play a larger role than the functionalization process in determining the evolution of aerosol water content and droplet size at high-oxidation stages.
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Jain, N., C. K. Liu, B. S. Hawkett, G. G. Warr i W. A. Hamilton. "Application of small-angle neutron scattering to the study of forces between magnetically chained monodisperse ferrofluid emulsion droplets". Journal of Applied Crystallography 47, nr 1 (25.12.2013): 41–52. http://dx.doi.org/10.1107/s1600576713030045.
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The optical magnetic chaining technique (MCT) developed by Leal-Calderon, Stora, Mondain-Monval, Poulin & Bibette [Phys. Rev. Lett.(1994),72, 2959–2962] allows precise measurements of force profiles between droplets in monodisperse ferrofluid emulsions. However, the method lacks anin situdetermination of droplet size and, therefore, requires a combination of separately acquired measurements of droplet chain periodicityversusan applied magnetic field from optical Bragg scattering and droplet diameter inferred from dynamic light scattering (DLS) to recover surface force–distance profiles between the colloidal particles. Compound refractive lens (CRL) focused small-angle neutron scattering (SANS) MCT should result in more consistent measurements of droplet size (form factor measurements in the absence of field) and droplet chaining period (from structure factor peaks when the magnetic field is applied), and, with access to shorter length scales, extend force measurements to closer approaches than possible by optical measurements. This article reports on CRL-SANS measurements of monodisperse ferrofluid emulsion droplets aligned in straight chains by an applied field perpendicular to the incident beam direction. Analysis of the scattering from the closely spaced droplets required algorithms that carefully treated resolution and its effect on mean scattering vector magnitudes in order to determine droplet size and chain periods to sufficient accuracy. At lower applied fields, scattering patterns indicate structural correlations transverse to the magnetic field direction owing to the formation of intermediate structures in early chain growth.
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Liu, Dongdong, i Tuan Tran. "The ejecting lamella of impacting compound droplets". Applied Physics Letters 115, nr 7 (12.08.2019): 073702. http://dx.doi.org/10.1063/1.5097370.
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Yao, Zhuosen, James E. Mungall i Kezhang Qin. "A Preliminary Model for the Migration of Sulfide Droplets in a Magmatic Conduit and the Significance of Volatiles". Journal of Petrology 60, nr 12 (1.12.2019): 2281–316. http://dx.doi.org/10.1093/petrology/egaa005.
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Abstract A close relationship between Ni–Cu–(PGE) sulfide deposits and magmatic conduit systems has been widely accepted, but our present understanding still rests on empirical inductions that sulfide liquids are entrained during magma ascent and aggregated at hydrodynamic traps such as the opening of a conduit into a larger magma body. In this contribution, a preliminary quantitative model for the dynamics of mm-scale sulfide droplets in a vertical magmatic conduit is developed, examining such limiting parameters as the size, transport velocity and the magmas’ maximum carrying capacity for sulfide droplets. Addition of numerous dense sulfide droplets significantly reduces magma buoyancy and rapidly increases the bulk viscosity, and the resulting pressure gradient in the propagating conduit dyke restricts the maximum volume fraction of droplets that can be carried by ascending magma. For sulfide droplets alone, the maximum carrying capacity is low, but it will be improved dramatically by the addition of volatiles which reduces the density and viscosity of silicate melt. Potential volatile degassing during decompression further facilitates sulfide entrainment by reducing bulk magma density, and the formation of buoyant compound vapour-sulfide liquid bubble drops also greatly enhances the carrying capacity. The breakdown of compound drops by detachment of parts of the vapour bubble or sulfide droplet may occur at low pressure, which liberates sulfide liquids from rising compound drops, potentially to collect in traps in the conduit system. When sulfide-laden magma flows through a widening conduit, many droplets can be captured by the re-circulation flow just downstream of the expanding section, followed by sulfide liquid accumulation and enhanced chemical interaction via diffusive exchange with the recirculating magma, potentially resulting in an economic, high-tonnage ore body. We apply our models to the emplacement of sulfide-rich magmatic suspensions at Noril’sk and show that the disseminated mineralization in intrusions could have formed when magmas carrying re-suspended sulfide liquid entrained from pre-existing sulfide accumulations in the conduit system reached their limiting sulfide carrying capacity as dictated by buoyancy and were deflected into blind sills flanking the principal conduit for flood basalt volcanism.
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Kalyuzhnaya, Dariya, Evgeniy Sokolov, Anastasia Vasilyeva, Irina Sutarina i Petr Ryapolov. "Dynamics of Nonmagnetic and Magnetic Emulsions in Microchannels of Various Materials". Fluids 8, nr 2 (25.01.2023): 42. http://dx.doi.org/10.3390/fluids8020042.
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The formation of droplets in microchannels (droplet microfluidics) has a large number of applications, such as in micro-dosing and gas meters. This paper considers the dynamics of direct and inverse emulsions based on water, polydimethylsiloxane, and synthetic and mineral oil in microfluidic chips based on two technologies: glass–parafilm–glass sandwich structures and removable scaffold in a silicone compound. It is shown that wettability, roughness and chip wall material; channel thickness; magnetic fluid flow rate; and magnetic field strength affect the size of emulsion droplets formed in a microfluidic chip. The addition of another mechanism for regulating the hydrodynamics of emulsions using a magnetic field opens up new possibilities for the development of promising devices.
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Iqbal, R., S. Dhiman, A. K. Sen i Amy Q. Shen. "Dynamics of a Water Droplet over a Sessile Oil Droplet: Compound Droplets Satisfying a Neumann Condition". Langmuir 33, nr 23 (26.05.2017): 5713–23. http://dx.doi.org/10.1021/acs.langmuir.6b04621.
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Stone, H. A., i L. G. Leal. "Breakup of concentric double emulsion droplets in linear flows". Journal of Fluid Mechanics 211 (luty 1990): 123–56. http://dx.doi.org/10.1017/s0022112090001525.
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The behaviour of concentric double emulsion droplets in linear flows is examined analytically, for the case when both fluid–fluid interfaces remain nearly spherical, and numerically, for the effect of finite interface deformation. The theoretical analysis is used to calculate the velocity fields interior and exterior to the particle, the first effects of flow-induced deformation, and the effective viscosity of a dilute emulsion of compound droplets. The numerical simulations allow for a complete investigation of the finite deformation of both the outer drop and the encapsulated particle. For concentric multiphase particles, there appear to be two distinct mechanisms of globule breakup: (i) continuous extension of the globule corresponding to non-existence of a steady particle shape or (ii) contact of the two interfaces at the globule centre, owing to incompatibility of the steady inner and outer interface shapes, even though the globule is only modestly deformed. Finally, the effect of different flow-types, i.e. uniaxial or biaxial extensional flows, is shown, in one example, to suggest breakup of the inner droplet even though the outer droplet maintains a steady shape.
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Chalella Mazzocato, Marcella, Sylvie Chevallier, Carmen S. Fávaro-Trindade i Denis Poncelet. "Monitoring the Capillary Jet Breakage by Vibration Using a Fast-Video Camera". Applied Sciences 11, nr 21 (1.11.2021): 10222. http://dx.doi.org/10.3390/app112110222.
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The production of beads by simple extrusion dropwise of an alginate solution in a calcium bath is a simple method. It may be done at room temperature without any toxic compound. However, simple extrusion drop by drop from a needle may result in large capsules and a low flow rate. The solution must be extruded as a jet to get a smaller size and higher flow rate, which breaks into droplets either by vibration or a cutting tool. The present contribution reports jet breakage observations into droplets under vibration by extruding an alginate solution varying some parameters during the study. The droplet formation was observed using a high-speed camera, and images were analyzed. The size, length before breakage, and droplet velocity were obtained by examining 50 droplets, and experiments were repeated three times. The high-speed camera allowed us to observe more precisely the capillary jet breakage. The study showed the importance of selecting a well-designed vibrating system, presented data while varying nozzle size, frequency, and flow rate to get optimum breakage keeping across all the same alginate solution. Further experiments would be interesting, modify the extruded solution concentration and composition, and find a precise criterion to identify optimum conditions.
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Bhopalam, Sthavishtha R., Jesus Bueno i Hector Gomez. "Elasto-capillary fluid–structure interaction with compound droplets". Computer Methods in Applied Mechanics and Engineering 400 (październik 2022): 115507. http://dx.doi.org/10.1016/j.cma.2022.115507.
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Che, Zhizhao, Yit Fatt Yap i Tianyou Wang. "Flow structure of compound droplets moving in microchannels". Physics of Fluids 30, nr 1 (styczeń 2018): 012114. http://dx.doi.org/10.1063/1.5008908.
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Arakawa, Sota, i Taishi Nakamoto. "Compound chondrule formation via collision of supercooled droplets". Icarus 276 (wrzesień 2016): 102–6. http://dx.doi.org/10.1016/j.icarus.2016.04.041.
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Cook, Ryan D., Ying-Hsuan Lin, Zhuoyu Peng, Eric Boone, Rosalie K. Chu, James E. Dukett, Matthew J. Gunsch i in. "Biogenic, urban, and wildfire influences on the molecular composition of dissolved organic compounds in cloud water". Atmospheric Chemistry and Physics 17, nr 24 (21.12.2017): 15167–80. http://dx.doi.org/10.5194/acp-17-15167-2017.
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Abstract. Organic aerosol formation and transformation occurs within aqueous aerosol and cloud droplets, yet little is known about the composition of high molecular weight organic compounds in cloud water. Cloud water samples collected at Whiteface Mountain, New York, during August–September 2014 were analyzed by ultra-high-resolution mass spectrometry to investigate the molecular composition of dissolved organic carbon, with a focus on sulfur- and nitrogen-containing compounds. Organic molecular composition was evaluated in the context of cloud water inorganic ion concentrations, pH, and total organic carbon concentrations to gain insights into the sources and aqueous-phase processes of the observed high molecular weight organic compounds. Cloud water acidity was positively correlated with the average oxygen : carbon ratio of the organic constituents, suggesting the possibility for aqueous acid-catalyzed (prior to cloud droplet activation or during/after cloud droplet evaporation) and/or radical (within cloud droplets) oxidation processes. Many tracer compounds recently identified in laboratory studies of bulk aqueous-phase reactions were identified in the cloud water. Organosulfate compounds, with both biogenic and anthropogenic volatile organic compound precursors, were detected for cloud water samples influenced by air masses that had traveled over forested and populated areas. Oxidation products of long-chain (C10−12) alkane precursors were detected during urban influence. Influence of Canadian wildfires resulted in increased numbers of identified sulfur-containing compounds and oligomeric species, including those formed through aqueous-phase reactions involving methylglyoxal. Light-absorbing aqueous-phase products of syringol and guaiacol oxidation were observed in the wildfire-influenced samples, and dinitroaromatic compounds were observed in all cloud water samples (wildfire, biogenic, and urban-influenced). Overall, the cloud water molecular composition depended on air mass source influence and reflected aqueous-phase reactions involving biogenic, urban, and biomass burning precursors.
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Varga, Z., G. Kiss i H. C. Hansson. "Modelling the cloud condensation nucleus activity of organic acids". Atmospheric Chemistry and Physics Discussions 7, nr 2 (19.04.2007): 5341–64. http://dx.doi.org/10.5194/acpd-7-5341-2007.
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Abstract. In this study vapour pressure osmometry was used to determine water activity in solutions of organic acids. The surface tension of the solutions was also monitored in parallel and then Köhler curves were calculated for nine organic acids (oxalic, malonic, succinic, glutaric, adipic acid, maleic acid, malic acid, citric acid and pinonic acid). Surface tension depression is negligible for most of the organic acids in dilute (≤1 w/w%) solutions. Therefore, these compounds affect the supersaturation only in the beginning phase of droplet formation but not necessarily at the critical size. An exception is cis-pinonic acid which remarkably depress surface tension also in dilute (0.1 w/w%) solution and hence at the critical point. The surface tension of organic acid solutions is influenced by the solubility of the compound, the length of the carbon chain and also by the polar functional groups present in the molecule. Similarly to surface tension solubility plays an important role also in water activity: compounds with higher solubility (e.g. malonic, maleic, and glutaric acid) reduce water activity significantly in the early phase of droplet formation while less soluble acids (e.g. succinic and adipic acid) are saturated in small droplets and the solution starts diluting only in bigger droplets. As a consequence, compounds with lower solubility have a minor effect on water activity in the early phase of droplet formation. To deduce the total effect Köhler curves were calculated and critical supersaturations were determined for the organic acids using measured surface tension and water activity. It was found that critical supersaturation grew with growing carbon number. Oxalic acid had the lowest critical supersaturation in the size range studied and it was comparable to the activation of ammonium sulfate. The Sc values obtained in this study were compared to data from CCNC measurements. In most cases good agreement was found.
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K. V. S., Chaithanya, i Sumesh P. Thampi. "Dynamics and stability of a concentric compound particle – a theoretical study". Soft Matter 15, nr 38 (2019): 7605–15. http://dx.doi.org/10.1039/c9sm01332f.
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Bermúdez, Miguel A., María A. Balboa i Jesús Balsinde. "Lipid Droplets, Phospholipase A2, Arachidonic Acid, and Atherosclerosis". Biomedicines 9, nr 12 (13.12.2021): 1891. http://dx.doi.org/10.3390/biomedicines9121891.
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Lipid droplets, classically regarded as static storage organelles, are currently considered as dynamic structures involved in key processes of lipid metabolism, cellular homeostasis and signaling. Studies on the inflammatory state of atherosclerotic plaques suggest that circulating monocytes interact with products released by endothelial cells and may acquire a foamy phenotype before crossing the endothelial barrier and differentiating into macrophages. One such compound released in significant amounts into the bloodstream is arachidonic acid, the common precursor of eicosanoids, and a potent inducer of neutral lipid synthesis and lipid droplet formation in circulating monocytes. Members of the family of phospholipase A2, which hydrolyze the fatty acid present at the sn-2 position of phospholipids, have recently emerged as key controllers of lipid droplet homeostasis, regulating their formation and the availability of fatty acids for lipid mediator production. In this paper we discuss recent findings related to lipid droplet dynamics in immune cells and the ways these organelles are involved in regulating arachidonic acid availability and metabolism in the context of atherosclerosis.
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Varga, Z., G. Kiss i H. C. Hansson. "Modelling the cloud condensation nucleus activity of organic acids on the basis of surface tension and osmolality measurements". Atmospheric Chemistry and Physics 7, nr 17 (7.09.2007): 4601–11. http://dx.doi.org/10.5194/acp-7-4601-2007.
Pełny tekst źródłaStreszczenie:
Abstract. In this study vapour pressure osmometry was used to determine water activity in the solutions of organic acids. The surface tension of the solutions was also monitored in parallel and then Köhler curves were calculated for nine organic acids (oxalic, malonic, succinic, glutaric, adipic, maleic, malic, citric and cis-pinonic). Surface tension depression is negligible for most of the organic acids in dilute (≤1 w/w%) solutions. Therefore, these compounds affect equilibrium vapour pressure only in the beginning phase of droplet formation when the droplet solution is more concentrated but not necessarily at the critical size. An exception is cis-pinonic acid which remarkably depress surface tension also in dilute (0.1 w/w%) solution and hence at the critical point. The surface tension of organic acid solutions is influenced by the solubility of the compound, the length of the carbon chain and also by the polar functional groups present in the molecule. Similarly to surface tension solubility plays an important role also in water activity: compounds with higher solubility (e.g. malonic, maleic and glutaric acid) reduce water activity significantly in the early phase of droplet formation while less soluble acids (e.g. succinic and adipic acid) are saturated in small droplets and the solution starts diluting only in bigger droplets. As a consequence, compounds with lower solubility have a minor effect on water activity in the early phase of droplet formation. To deduce the total effect Köhler curves were calculated and critical supersaturations (Sc) were determined for the organic acids using measured surface tension and water activity. It was found that critical supersaturation grew with growing carbon number. Oxalic acid had the lowest critical supersaturation in the size range studied and it was comparable to the activation of ammonium sulphate. The Sc values obtained in this study were compared to data from CCNC experiments. In most cases good agreement was found. For modelling purposes Sc vs. ddry plots are given and the dependence of water activity and surface tension on concentration are also formulated.
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Berli, Claudio L. A., i Martín G. Bellino. "Nanotextured Surfaces Lead to Differential Wettability of Compound Droplets". Advanced Materials Interfaces 8, nr 15 (14.07.2021): 2100714. http://dx.doi.org/10.1002/admi.202100714.
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Liu, Meifang, Lin Su, Jie Li, Sufen Chen, Yiyang Liu, Jing Li, Bo Li, Yongping Chen i Zhanwen Zhang. "Investigation of spherical and concentric mechanism of compound droplets". Matter and Radiation at Extremes 1, nr 4 (lipiec 2016): 213–23. http://dx.doi.org/10.1016/j.mre.2016.07.002.
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Chen, Chun-Kuei, Wei-Mon Yan i Ta-Hui Lin. "Experimental study on streamwise interaction of burning compound droplets". Case Studies in Thermal Engineering 21 (październik 2020): 100707. http://dx.doi.org/10.1016/j.csite.2020.100707.
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Liu, Dongdong, i Tuan Tran. "Emergence of two lamellas during impact of compound droplets". Applied Physics Letters 112, nr 20 (14.05.2018): 203702. http://dx.doi.org/10.1063/1.5026821.
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Riupassa, Helen, Suyatno Suyatno, Hendry Y. Nanlohy, Andi Sanata, Trismawati Trismawati, Rachmat Subagyo, Satworo Adiwidodo i in. "Effects of Eugenol and Cineol Compound on Diffusion Burning Rate Characteristics of Crude Coconut Oil Droplet". Automotive Experiences 6, nr 1 (28.01.2023): 59–67. http://dx.doi.org/10.31603/ae.8150.
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The burning rate of coconut oil droplets has been investigated experimentally by adding bio-additives of clove oil and eucalyptus oil. Tests were carried out with single droplets suspended on thermocouples at room atmospheric pressure, and room temperature and ignited with a hot wire. The addition of clove oil and eucalyptus oil as bio-additives into coconut oil was 100 ppm and 300 ppm, respectively. The droplet combustion method was chosen to increase the contact area between the air and fuel so that the reactivity of the fuel molecules increases. The results showed that the eugenol compounds contained in clove oil and cineol compounds in eucalyptus oil were both aromatic, and had an unsymmetrical carbon chain geometry structure. Furthermore, this factor can potentially accelerate the occurrence of effective collisions between fuel molecules. Therefore the fuel is combustible, as evidenced by the increased burning rate, where the results show that without bio-additives, the burning rate of crude coconut oil (CCO) is about 0.7 seconds. These results are 0.15 to 0.2 seconds slower than CCO with bio-additive, which is around 0.55 to 0.6 seconds. Moreover, from the observations, it was found that the highest burning rate was achieved in both bio-additives with a concentration of 300 ppm.
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Huang, Y. J., M. Q. Kong, G. L. Chen, Q. Yang i G. X. Li. "Formation and dynamics of core–shell droplets in immiscible polymer blends". RSC Adv. 4, nr 81 (2014): 43150–54. http://dx.doi.org/10.1039/c4ra07229d.
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Sorjamaa, R., T. Raatikainen i A. Laaksonen. "The role of surfactants in Köhler theory reconsidered". Atmospheric Chemistry and Physics Discussions 4, nr 3 (19.05.2004): 2781–804. http://dx.doi.org/10.5194/acpd-4-2781-2004.
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Abstract. Atmospheric aerosol particles typically consist of inorganic salts and organic material. The inorganic compounds as well as their hygroscopic properties are well defined, but the effect of organic compounds on cloud droplet activation is still poorly characterized. The focus of the present study is in the organic compounds that are surface active i.e. they concentrate on droplet surface and decrease droplet surface tension. Gibbsian surface thermodynamics were used to find out how partitioning in binary and ternary aqueous solutions affects the droplet surface tension and the droplet bulk concentration in droplets large enough to act as cloud condensation nuclei. Sodium dodecyl sulfate was used as a model compound together with sodium chloride to find out the effect the correct evaluation of surfactant partitioning has on the solute effect (Raoult effect). While the partitioning is known to lead to higher surface tension compared to a case in which partitioning is neglected, the present results show that the partitioning also alters the solute effect, and that the change is large enough to further increase the critical supersaturation and hence decrease the droplet activation. The fraction of surfactant partitioned to droplet surface increases with decreasing droplet size, which suggests that surfactants might enhance the activation of larger particles relatively more thus leading to less dense clouds. Cis-pinonic acid-ammonium sulfate aqueous solution was studied in order to relate the partitioning to more realistic atmospheric situation and to find out the combined effects of dissolution and partitioning behaviour. The results show that correct partitioning consideration alters the shape of the Köhler curve when compared to a situation in which the partitioning is neglected either completely or in the Raoult effect.
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Marsh, Aleksandra, Rachael E. H. Miles, Grazia Rovelli, Alexander G. Cowling, Lucy Nandy, Cari S. Dutcher i Jonathan P. Reid. "Influence of organic compound functionality on aerosol hygroscopicity: dicarboxylic acids, alkyl-substituents, sugars and amino acids". Atmospheric Chemistry and Physics 17, nr 9 (3.05.2017): 5583–99. http://dx.doi.org/10.5194/acp-17-5583-2017.
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Abstract. Hygroscopicity data for 36 organic compounds, including amino acids, organic acids, alcohols and sugars, are determined using a comparative kinetics electrodynamic balance (CK-EDB). The CK-EDB applies an electric field to trap-charged aqueous droplets in a chamber with controlled temperature and relative humidity (RH). The dual micro dispenser set-up allows for sequential trapping of probe and sample droplets for accurate determination of droplet water activities from 0.45 to > 0.99. Here, we validate and benchmark the CK-EDB for the homologous series of straight-chain dicarboxylic acids (oxalic–pimelic) with measurements in better agreement with Universal Quasichemical Functional Group Activity Coefficients (UNIFAC) predictions than the original data used to parametrise UNIFAC. Furthermore, a series of increasingly complex organic compounds, with subtle changes to molecular structure and branching, are used to rigorously assess the accuracy of predictions by UNIFAC, which does not explicitly account for molecular structure. We show that the changes in hygroscopicity that result from increased branching and chain length are poorly represented by UNIFAC, with UNIFAC under-predicting hygroscopicity. Similarly, amino acid hygroscopicity is under-predicted by UNIFAC predictions, a consequence of the original data used in the parametrisation of the molecular subgroups. New hygroscopicity data are also reported for a selection of alcohols and sugars and they show variable levels of agreement with predictions.
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Zhang, Jifen, Jiao Zhang, Shuai Wang i Tao Yi. "Development of an Oral Compound Pickering Emulsion Composed of Nanocrystals of Poorly Soluble Ingredient and Volatile Oils from Traditional Chinese Medicine". Pharmaceutics 10, nr 4 (1.10.2018): 170. http://dx.doi.org/10.3390/pharmaceutics10040170.
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In this study, an oral drug nanocrystals self-stabilized Pickering emulsion (NSSPE), which used nanocrystals of a poorly soluble ingredient from Puerariae Radix called puerarin as solid particle stabilizers and Ligusticum chuanxiong essential oil since the main oil phase had been developed to improve the oral bioavailability of puerarin. The appearance of emulsions, size and zeta potential of droplets, and content of puerarin in emulsified layer during a storage of six months at 4, 25, and 40 °C were investigated. The centrifugation stability at 4000× g was also studied. The micro-structure of emulsion droplets was characterized by a scanning electron micrograph (SEM), confocal laser scanning microscopy (CLSM), a fluorescence microscope (FM), and differential scanning calorimetry (DSC). The in vivo oral bioavailability of puerarin NSSPE was investigated in rats. Results showed that appearances of puerarin NSSPE kept stable after centrifugation at 4000× g for 15 min or storage for six months at 4, 25, and 40 °C. SEM, CLSM, FM, and DSC showed that the puerarin NSSPE had a stable core-shell structure of emulsion droplets formed by the adsorption of puerarin nanocrystals on the surface of oil droplets of mixed oil of Ligusticum chuanxiong essential oil and Labrafil M 1944 CS (9:1, v/v). The relative bioavailability of puerarin NSSPE to puerarin coarse powder suspension, nanocrystal suspension, and surfactant emulsion were 262.43%, 155.92%, and 223.65%, respectively. All these results indicated that puerarin nanocrystals could stabilize Pickering emulsion of Ligusticum chuanxiong essential oil without any other stabilizers and Pickering emulsion could improve the oral bioavailability of puerarin, which suggests that the drug nanocrystal self-stabilized Pickering emulsion as a promising oral drug delivery system for Traditional Chinese Medicine containing poorly soluble ingredients and volatile oils.
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Epstein, S. A., E. Tapavicza, F. Furche i S. A. Nizkorodov. "Direct photolysis of carbonyl compounds dissolved in cloud and fog droplets". Atmospheric Chemistry and Physics Discussions 13, nr 4 (24.04.2013): 10905–37. http://dx.doi.org/10.5194/acpd-13-10905-2013.
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Abstract. Gas phase photolysis is an important tropospheric sink for many carbonyl compounds, however the significance of direct photolysis of carbonyl compounds dissolved in cloud and fog droplets is uncertain. We develop a theoretical approach to assess the importance of aqueous photolysis for a series of carbonyls that possess carboxyl and hydroxyl functional groups by comparison with rates of other atmospheric processes. We use computationally and experimentally derived Henry's law parameters, hydration equilibrium parameters, aqueous hydroxyl radical (OH) rate constants, and optical extinction coefficients to identify types of compounds that will not have competitive aqueous photolysis rates. We also present molecular dynamics simulations of atmospherically relevant carbonyl compounds designed to estimate gas and aqueous phase extinction coefficients. In addition, experiments designed to measure the photolysis rate of glyceraldehyde, an atmospherically relevant water soluble organic compound, reveal that aqueous quantum yields are highly molecule-specific and cannot be extrapolated from measurements of structurally similar compounds. We find that only three out of the 92 carbonyl compounds investigated, pyruvic acid, 3-oxobutanoic acid, and 3-oxopropanoic acid, may have aqueous photolysis rates that exceed the rate of oxidation by dissolved OH. For almost all carbonyl compounds lacking α, β conjugation, atmospheric removal by direct photolysis in cloud and fog droplets can be neglected.
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Liu, Meifang, Yueqing Zheng, Yiyang Liu, Zhanwen Zhang, Yuguang Wang, Qiang Chen, Jing Li, Jie Li, Yawen Huang i Qiang Yin. "Effects of surfactant adsorption on the formation of compound droplets in microfluidic devices". RSC Advances 9, nr 71 (2019): 41943–54. http://dx.doi.org/10.1039/c9ra07141e.
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Meng, Xianze, Yongli Wang, Xin Li, Xue Chen, Dongjun Lv, Chuang Xie, Qiuxiang Yin, Xuling Zhang i Hongxun Hao. "Confined Crystallization of Pigment Red 146 in Emulsion Droplets and Its Mechanism". Nanomaterials 9, nr 3 (6.03.2019): 379. http://dx.doi.org/10.3390/nano9030379.
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In this work, the effect of confined space on crystallization processes of pigments was investigated by using C.I. Pigment Red 146 (PR 146) as a model compound. The colloidal system (i.e., emulsion droplets) was used as a nanoreactor to prepare nanoscale PR 146 for the inkjet printer. The effects of the space confinement were investigated by comparing the products of PR 146 prepared from bulk solution, macroemulsion, and miniemulsion. The results showed that PR 146 crystallized in mini-emulsion had the narrowest particle size distribution and the average particle size can be as small as 172.5 nm, one order of magnitude smaller than the one obtained from the bulk solution. X-ray diffraction (XRD) data revealed that PR 146 crystallized in all three solutions where the crystalline state and had similar crystallite sizes. The process mechanism of crystallization confined in the miniemulsion droplets was proposed and explained. The function mechanism of the co-stabilizer during the crystallization of PR 146 in emulsion was also explained. It was found that sodium chloride could counteract the pressure difference as an osmotic pressure agent and prevent the migrating of water from small droplets into big droplets. The influences of dosages of emulsifiers and co-stabilizers on droplet size and the size of the obtained PR 146 particles were evaluated and the optimal conditions were determined. Furthermore, the disparity of PR 146 products prepared by different methods was investigated by UV–Vis spectra. The aqueous dispersion of PR 146 crystallized in miniemulsion had the highest absorbance and darkest color.
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Wang, Bo, Haiyan Tian i Dong Xiang. "Stabilizing the Oil-in-Water Emulsions Using the Mixtures of Dendrobium Officinale Polysaccharides and Gum Arabic or Propylene Glycol Alginate". Molecules 25, nr 3 (10.02.2020): 759. http://dx.doi.org/10.3390/molecules25030759.
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Coconut oil-in-water emulsions were prepared using three polysaccharides: Dendrobium officinale polysaccharide (DOP), propylene glycol alginate (PGA), gum arabic (GA) and their polysaccharide complexes as emulsifiers. The effects of the ratio of the compounded polysaccharides on their apparent viscosity and interfacial activity were explored in this study. The average particle size, zeta potential, microstructure, rheological properties, and physical stability of the emulsions prepared with different compound-polysaccharides were studied. The results showed that mainly DOP contributed to the apparent viscosity of the compound-polysaccharide, while the interfacial activity and zeta potential were mainly influenced by PGA or GA. Emulsions prepared with compound-polysaccharides exhibited smaller average particle sizes, and microscopic observations showed smaller droplets and less droplet aggregation. In addition, the stability analysis of emulsions by a dispersion analyzer LUMiSizer showed that the emulsion prepared by compounding polysaccharides had better physical stability. Finally, all of the above experimental results showed that the emulsions prepared by PGA:DOP = 2:8 (total concentration = 1.5 wt%) and 2.0% GA + 1.5% DOP were the most stable.
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Vu, Truong V., Vinh T. Nguyen, Phan H. Nguyen, Nang X. Ho, Binh D. Pham, Hoe D. Nguyen i Hung V. Vu. "Dynamics of a contracting fluid compound filament with a variable density ratio". Science and Technology Development Journal 24, nr 2 (10.05.2021): first. http://dx.doi.org/10.32508/stdj.v24i2.2515.
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Introduction: Compound fluid filaments appear in many applications, e.g., drug delivery and processing or microfluidic systems. This paper focuses on the numerical simulation of an incompressible, immiscible, and Newtonian fluid for the contraction process of a fluid compound filament by solving the Navier-Stokes equations. The front-tracking method is used to solve this problem, which uses connected segments (Lagrangian grid) that move on a fixed grid (Eulerian grid) to represent the interface between the liquids.
Methods: The interface points are advected by the velocity interpolated from those of the fixed grid using the area weighting function. The coordinates of the interface points are used to construct the indicators specifying the different fluids and compute the interfacial tension force.
Results: The simulation results show that under the effects of the interfacial tension, the capsuleshaped filament can transform into a spherical compound droplet (i.e., non-breakup) or can break up into smaller spherical compound and simple droplets (i.e., breakup). When the density ratio of the outer to middle fluids increases, the filament changes from non-breakup to breakup upon contraction.
Conclusion: Increasing the density ratio enhances the breakup of the compound filament during contraction. The breakup is also promoted by increasing the initial length of the filament.