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1
Bromley, Keith M., e Cait E. MacPhee. "BslA-stabilized emulsion droplets with designed microstructure". Interface Focus 7, n. 4 (16 giugno 2017): 20160124. http://dx.doi.org/10.1098/rsfs.2016.0124.
Testo completoAbstract (sommario):
Emulsions are a central component of many modern formulations in food, pharmaceuticals, agrichemicals and personal care products. The droplets in these formulations are limited to being spherical as a consequence of the interfacial tension between the dispersed phase and continuous phase. The ability to control emulsion droplet morphology and stabilize non-spherical droplets would enable the modification of emulsion properties such as stability, substrate binding, delivery rate and rheology. One way of controlling droplet microstructure is to apply an elastic film around the droplet to prevent it from relaxing into a sphere. We have previously shown that BslA, an interfacial protein produced by the bacterial genus Bacillus , forms an elastic film when exposed to an oil- or air–water interface. Here, we highlight BslA's ability to stabilize anisotropic emulsion droplets. First, we show that BslA is capable of arresting dynamic emulsification processes leading to emulsions with variable morphologies depending on the conditions and emulsification technique applied. We then show that frozen emulsion droplets can be manipulated to induce partial coalescence. The structure of the partially coalesced droplets is retained after melting, but only when there is sufficient free BslA in the continuous phase. That the fidelity of replication can be tuned by adjusting the amount of free BslA in solution suggests that freezing BslA-stabilized droplets disrupts the BslA film. Finally, we use BslA's ability to preserve emulsion droplet structural integrity throughout the melting process to design emulsion droplets with a chosen shape and size.
2
Yong, Ah Pis, Md Aminul Islam e Nurul Hasan. "The Effect of pH and High-Pressure Homogenization on Droplet Size". International Journal of Engineering Materials and Manufacture 2, n. 4 (10 dicembre 2017): 110–22. http://dx.doi.org/10.26776/ijemm.02.04.2017.05.
Testo completoAbstract (sommario):
The aims of this study are to revisit the effect of high pressure on homogenization and the influence of pH on the emulsion droplet sizes. The high-pressure homogenization (HPH) involves two stages of processing, where the first stage involves in blending the coarse emulsion by a blender, and the second stage requires disruption of the coarse emulsion into smaller droplets by a high-pressure homogenizer. The pressure range in this review is in between 10-500 MPa. The homogenised droplet sizes can be reduced by increasing the homogenization recirculation, and there is a threshold point beyond that by applying pressure only, the size cannot be further reduced. Normally, homogenised emulsions are classified by their degree of kinetic stability. Dispersed phase present in the form of droplets while continuous phase also known as suspended droplets. With a proper homogenization recirculation and pressure, a more kinetically stable emulsion can be produced. The side effects of increasing homogenization pressure are that it can cause overprocessing of the emulsion droplets where the droplet sizes become larger rather than the expected smaller size. This can cause kinetic instability in the emulsion. The droplet size is usually measured by dynamic light scattering or by laser light scattering technique. The type of samples used in this reviews are such as chocolate and vanilla based powders; mean droplet sizes samples; basil oil; tomato; lupin protein; oil; skim milk, soymilk; coconut milk; tomato homogenate; corn; egg-yolk, rapeseed and sunflower; Poly(4-vinylpyridine)/silica; and Complex 1 until complex 4 approaches from author case study. A relationship is developed between emulsion size and pH. Results clearly show that lower pH offers smaller droplet of emulsion and the opposite occurs when the pH is increased.
3
Silva, T. M., N. N. P. Cerize e A. M. Oliveira. "The Effect of High Shear Homogenization on Physical Stability of Emulsions". International Journal of Chemistry 8, n. 4 (28 settembre 2016): 52. http://dx.doi.org/10.5539/ijc.v8n4p52.
Testo completoAbstract (sommario):
<p class="03Abstract">Emulsions are thermodynamically unstable systems where droplet size is one of the main factors that affect its physical stability and consequently their quality. In this context, this work analyses the incorporation of a high shear homogenization step in the manufacturing process of an emulsion with the objective of maintaining its physical stability. In order to demonstrate the effects of this homogenization in the manufacturing process, the emulsion characterization was carried out by microscopy, rheology, laser diffraction and analytical photo-centrifugation techniques. The effect of high shear homogenization into the emulsion physical results was dependent on the speed applied to the homogenizer pump, with an effective 3600 rpm speed. There was no evidence of change on pH attributes and emulsion density, although there was a change in volumetric relationship between the droplet family presented in each sample, reducing the population of larger droplets to form a third family of intermediate droplets and increasing the volumetric proportion of the population of smaller droplets. This profile change in the droplet size distribution contributed to increased viscosity and emulsion without the presence of separation after it was submitted to the stress condition of temperature and agitation.</p>
4
Li, Chun, Jian Ouyang, Fangjie Dou e Jingtao Shi. "Mechanism Influencing the Drying Behavior of Bitumen Emulsion". Materials 14, n. 14 (12 luglio 2021): 3878. http://dx.doi.org/10.3390/ma14143878.
Testo completoAbstract (sommario):
The drying process of bitumen emulsion largely dominates the strength development of emulsion-based mixtures for pavement structure, thus it can be used to judge the quality of bitumen emulsion. However, the drying behaviour of bitumen emulsions was seldom considered. The emulsion drying and film formation theory are employed to study the drying process of different bitumen emulsions with a thin layer. Results indicated the drying process of bitumen emulsion can be divided into three stages: (a) an initial high evaporation rate stage; (b) an intermediate stage with a rapidly decreasing evaporation rate; (c) a final stage with a very small evaporation rate. The boundaries among the three stages can be identified by studying the water evaporation rate. Three drying parameters, i.e., the critical volume fractions of bitumen defining the boundaries among the three stages and the maximum packing fraction of bitumen droplets, are proposed to quantitatively characterize the drying behavior of bitumen emulsion. High values of these parameters indicate a bitumen emulsion that has rapid drying behavior. Therefore, these parameters are independent of the emulsifier type, but they are highly dependent on the bitumen’s droplet size. These drying parameters increase with a decrease in bitumen droplet size. Therefore, bitumen emulsion with a smaller size distribution of bitumen droplets can have a more rapid drying behavior, which is recommended in real engineering.
5
Jiang, Tianyi, Yankai Jia, Haizhen Sun, Xiaokang Deng, Dewei Tang e Yukun Ren. "Dielectrophoresis Response of Water-in-Oil-in-Water Double Emulsion Droplets with Singular or Dual Cores". Micromachines 11, n. 12 (17 dicembre 2020): 1121. http://dx.doi.org/10.3390/mi11121121.
Testo completoAbstract (sommario):
Microfluidic technologies have enabled generation of exquisite multiple emulsion droplets, which have been used in many fields, including single-cell assays, micro-sized chemical reactions, and material syntheses. Electrical controlling is an important technique for droplet manipulation in microfluidic systems, but the dielectrophoretic behaviors of multiple emulsion droplets in electrical fields are rarely studied. Here, we report on the dielectrophoresis response of double emulsion droplets in AC electric fields in microfluidic channel. A core-shell model is utilized for analyzing the polarization of droplet interfaces and the overall dielectrophoresis (DEP) force. The water-in-oil-in-water droplets, generated by glass capillary devices, experience negative DEP at low field frequency. At high frequency, however, the polarity of DEP is tunable by adjusting droplet shell thickness or core conductivity. Then, the behavior of droplets with two inner cores is investigated, where the droplets undergo rotation before being repelled or attracted by the strong field area. This work should benefit a wide range of applications that require manipulation of double emulsion droplets by electric fields.
6
Spicer, Patrick T., e Richard W. Hartel. "Crystal Comets: Dewetting During Emulsion Droplet Crystallization". Australian Journal of Chemistry 58, n. 9 (2005): 655. http://dx.doi.org/10.1071/ch05119.
Testo completoAbstract (sommario):
Liquid oil emulsion droplets can violently dewet their own solid crystals during crystallization as a result of surfactant adsorption. The crystal shape formed is a function of the relative rates of dewetting and crystallization as controlled by surfactant adsorption, cooling rate, and lipid purity. For negligible dewetting rates, crystals nucleate and grow within the droplet. At similar crystallization and dewetting rates, the droplet is propelled around the continuous phase on a crystalline ‘comet tail’ much larger than the original droplet. Rapid dewetting causes the ejection of small discrete crystals across the droplet’s oil–water interface.
7
Zheng, Hongxia, Like Mao, Jingyi Yang, Chenyu Zhang, Song Miao e Yanxiang Gao. "Effect of Oil Content and Emulsifier Type on the Properties and Antioxidant Activity of Sea Buckthorn Oil-in-Water Emulsions". Journal of Food Quality 2020 (13 gennaio 2020): 1–8. http://dx.doi.org/10.1155/2020/1540925.
Testo completoAbstract (sommario):
Sea buckthorn oil-in-water emulsions were prepared through high pressure homogenization, and the effects of droplet size, oil content, and emulsifier type on emulsion properties and the overall antioxidant activity of the emulsions were evaluated. Emulsions with different droplet size were obtained by varying homogenization pressure, and higher oil content resulted in bigger droplet size of the emulsions. Among three tested emulsifiers, sodium caseinate and sugar ester were able to form emulsions with much smaller particle size than soy protein isolate. The emulsions with bigger droplets tended to cream in an accelerated centrifugation test. The antioxidant property of the emulsions was expressed as their DPPH radical scavenging activity. The emulsions processed at lower pressure or contained higher oil content had higher DPPH radical scavenging activity. The soy protein isolate-stabilized emulsion presented higher antioxidant activity than sodium caseinate- and sugar ester-stabilized ones. Upon storage, the antioxidant activity of the emulsions was decreased due to the changes in emulsion stability and the degradation of antioxidants. The knowledge obtained in this study would be useful in developing healthy food containing sea buckthorn oil.
8
Fingas, Merv. "OIL SPILL DISPERSION STABILITY AND OIL RE-SURFACING". International Oil Spill Conference Proceedings 2008, n. 1 (1 maggio 2008): 661–65. http://dx.doi.org/10.7901/2169-3358-2008-1-661.
Testo completoAbstract (sommario):
ABSTRACT This paper summarizes the data and the theory of oil-in-water emulsion stability resulting in oil spill dispersion re-surfacing. There is an extensive body of literature on surfactants and interfacial chemistry, including experimental data on emulsion stability. The phenomenon of resurfacing oil is the result of two separate processes: de stabilization of an oil-in-water emulsion and desorption of surfactant from the oil-water interface which leads to further de stabilization. The de stabilization of oil-in-water emulsions such as chemical oil dispersions is a consequence of the fact that no emulsions are thermodynamically stable. Ultimately, natural forces move the emulsions to a stable state, which consists of separated oil and water. What is important is the rate at which this occurs. An emulsion is said to be kinetically stable when significant separation (usually considered to be half or 50% of the dispersed phase) occurs outside of the usable time. There are several forces and processes that result in the destabilization and resurfacing of oil-in-water emulsions such as chemically dispersed oils. These include gravitational forces, surfactant interchange with water and subsequent loss of surfactant to the water column, creaming, coalescence, flocculation, Ostwald ripening, and sedimentation. Gravitational separation is the most important force in the resurfacing of oil droplets from crude oil-in-water emulsions such as dispersions. Droplets in an emulsion tend to move upwards when their density is lower than that of water. Creaming is the de stabilization process that is simply described by the appearance of the starting dispersed phase at the surface. Coalescence is another important de stabilization process. Two droplets that interact as a result of close proximity or collision can form a new larger droplet. The result is to increase the droplet size and the rise rate, resulting in accelerated de stabilization of the emulsion. Studies show that coalescence increases with increasing turbidity as collisions between particles become more frequent. Another important phenomenon when considering the stability of dispersed oil, is the absorption/desorption of surfactant from the oil/water interface. In dilute solutions, much of the surfactant in the dispersed droplets ultimately partitions to the water column and thus is lost to the dispersion process. This paper provides a summary of the processes and data from some experiments relevant to oil spill dispersions.
9
Xu, Ke, Peixi Zhu, Tatiana Colon, Chun Huh e Matthew Balhoff. "A Microfluidic Investigation of the Synergistic Effect of Nanoparticles and Surfactants in Macro-Emulsion-Based Enhanced Oil Recovery". SPE Journal 22, n. 02 (23 settembre 2016): 459–69. http://dx.doi.org/10.2118/179691-pa.
Testo completoAbstract (sommario):
Summary Injecting oil-in-water (O/W) emulsions stabilized with nanoparticles (NPs) or surfactants is a promising option for enhanced oil recovery (EOR) in harsh-condition reservoirs. Stability and rheology of the flowing emulsion in porous media are key factors for the effectiveness of the EOR method. The objective of this study is to use microfluidics to (1) quantitatively evaluate the synergistic effect of surfactants and NPs on emulsion dynamic stability and how NPs affect the emulsion properties, and to (2) investigate how emulsion properties affect the sweep performance in emulsion flooding. A microfluidic device with well-defined channel geometry of a high-permeability pathway and multiple parallel low-permeability pathways was created to represent a fracture/matrix dual-permeability system. Measurement of droplet coalescence frequency during flow is used to quantify the dynamic stability of emulsions. An NP aqueous suspension (2 wt%) shows excellent ability to stabilize the macro-emulsion when mixed with a trace amount of surfactant (0.05 wt%), revealing a synergistic effect between NPs and surfactant. For a stable emulsion, when a pore throat is present in the high-permeability pathway, it was observed that flowing emulsion droplets compress each other and then block the high-permeability pathway at a throat structure, which forces the wetting phase into low-permeability pathways. Droplet size shows little correlation with this blocking effect. Water content was observed to be much higher in the low-permeability pathways than in the high-permeability pathways, indicating different emulsion texture and viscosity in channels of different sizes. Consequently, the assumption of bulk emulsion viscosity in the porous medium is not applicable in the description and modeling of the emulsion-flooding process. Flow of emulsions stabilized by an NP/surfactant mixture shows droplet packing in high-permeability regions that is denser than those stabilized by surfactant only, at high-permeability regions, which is attributed to the enhanced interaction between droplets caused by NPs in the thin liquid film between neighboring oil/water (O/W) interfaces. This effect is shown to enhance the performance of emulsion-blockage effect for sweep-efficiency improvement, showing the advantage of NPs as an emulsion stabilizer during an emulsion-based EOR process.
10
Jarzębski, Maciej, Przemysław Siejak, Wojciech Smułek, Farahnaz Fathordoobady, Yigong Guo, Jarosław Pawlicz, Tomasz Trzeciak et al. "Plant Extracts Containing Saponins Affects the Stability and Biological Activity of Hempseed Oil Emulsion System". Molecules 25, n. 11 (10 giugno 2020): 2696. http://dx.doi.org/10.3390/molecules25112696.
Testo completoAbstract (sommario):
In this study, two saponins-rich plant extracts, viz. Saponaria officinalis and Quillaja saponaria, were used as surfactants in an oil-in-water (O/W) emulsion based on hempseed oil (HSO). This study focused on a low oil phase content of 2% v/v HSO to investigate stable emulsion systems under minimum oil phase conditions. Emulsion stability was characterized by the emulsification index (EI), centrifugation tests, droplet size distribution as well as microscopic imaging. The smallest droplets recorded by dynamic light scattering (droplets size v. number), one day after the preparation of the emulsion, were around 50–120 nm depending the on use of Saponaria and Quillaja as a surfactant and corresponding to critical micelle concentration (CMC) in the range 0–2 g/L. The surface and interfacial tension of the emulsion components were studied as well. The effect of emulsions on environmental bacteria strains was also investigated. It was observed that emulsions with Saponaria officinalis extract exhibited slight toxic activity (the cell metabolic activity reduced to 80%), in contrast to Quillaja emulsion, which induced Pseudomonas fluorescens ATCC 17400 growth. The highest-stability samples were those with doubled CMC concentration. The presented results demonstrate a possible use of oil emulsions based on plant extract rich in saponins for the food industry, biomedical and cosmetics applications, and nanoemulsion preparations.
11
Wardhono, Endarto Yudo, Mekro Permana Pinem, Hadi Wahyudi e Sri Agustina. "Calorimetry Technique for Observing the Evolution of Dispersed Droplets of Concentrated Water-in-Oil (W/O) Emulsion during Preparation, Storage and Destabilization". Applied Sciences 9, n. 24 (4 dicembre 2019): 5271. http://dx.doi.org/10.3390/app9245271.
Testo completoAbstract (sommario):
In this work, the evolution of dispersed droplets in a water-in-oil (W/O) emulsion during formation, storage, and destabilization was observed using a calorimetry technique. The emulsion was prepared by dispersing drop by drop an aqueous phase into an oil continuous phase at room temperature using a rotor-stator homogenizer. The evolution of droplets during (1) preparation; (2) storage; and (3) destabilization was observed using differential scanning calorimetry (DSC). The samples were gently cooled-down below its solid-liquid equilibrium temperature then heated back above the melting point to determine its freezing temperature. The energy released during the process was recorded in order to get information about the water droplet dispersion state. The mean droplet size distribution of the sample emulsion was correlated to its freezing temperature and the morphology was followed by optical microscopy. The results indicated that the calorimetry technique is so far a very good technique of characterization concentrated W/O emulsions.
12
Miao, Chuanwei, Mani Tayebi e Wadood Y. Hamad. "Investigation of the formation mechanisms in high internal phase Pickering emulsions stabilized by cellulose nanocrystals". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 376, n. 2112 (25 dicembre 2017): 20170039. http://dx.doi.org/10.1098/rsta.2017.0039.
Testo completoAbstract (sommario):
Medium and high internal phase Pickering emulsions stabilized by cellulose nanocrystals (CNCs) have been prepared and the effects of CNC concentration and type of oil phase on the properties of emulsions were studied. The maximum oil phase volume that can be stabilized by CNCs is 87% when the CNC concentration is 0.6 wt.%; this slightly decreases to 83% when the CNC concentration is increased to 1.2 wt.% or higher. In addition, the oil droplets stabilized with 0.6 wt.% CNC suspensions have a larger size than those stabilized with higher concentration CNC suspensions. As evidenced by the change in oil droplet morphology and size, two different emulsion formation mechanisms are proposed. For a CNC concentration of 0.6 wt.%, the extra oil added into the emulsion is accommodated by the expansion of oil droplet size, whereas for CNC concentrations of 1.2 wt.% and higher, the oil is stabilized mainly by the formation of new oil droplets.
13
Egley, Grant H., James E. Hanks e C. Douglas Boyette. "Invert Emulsion Droplet Size and Mycoherbicidal Activity ofColletotrichum truncatum". Weed Technology 7, n. 2 (giugno 1993): 417–24. http://dx.doi.org/10.1017/s0890037x00027822.
Testo completoAbstract (sommario):
When formulated and sprayed in an invert emulsion (IE), conidia of the mycoherbicide,Colletotrichum truncatum, controlled hemp sesbania in the absence of dew. To optimize hemp sesbania control, formulation droplet size influence upon the pathogen's germination and pathogenicity was investigated. Conidia germination in manually produced IE droplets decreased from 46% to 5% as droplet diameter decreased from 2700 to 900μm. Droplet size did not affect appressoria formation. On a per conidium basis, 900-μm droplets were more pathogenic to detached hemp sesbania leaves than were 2100-μm droplets. An air-assist spray system produced droplet spectra with volume median diameters of 421 and 104μm, respectively. The spectrum of smaller droplets covered the target better than did that of larger droplets. When applied to whole hemp sesbania plants in greenhouse trials, conidia in the smaller and larger droplet spectra gave 90 and 94% control, respectively. Sufficient conidia germinated in IE droplets of a variety of sizes to control hemp sesbania excellently.
14
Xu, Xia, Hong Chen, Qi Zhang, Fei Lyu, Yuting Ding e Xuxia Zhou. "Effects of Oil Droplet Size and Interfacial Protein Film on the Properties of Fish Myofibrillar Protein–Oil Composite Gels". Molecules 25, n. 2 (10 gennaio 2020): 289. http://dx.doi.org/10.3390/molecules25020289.
Testo completoAbstract (sommario):
The effects of oil droplet size and the formation of an interfacial protein film (IPF) on silver carp myofibrillar protein (MP)–oil composite gels were studied. MP- or Tween 80-stabilized camellia seed oil emulsions with different droplet sizes were prepared and added to MPs to prepare composite gels. The oil droplet size of the Tween 80-stabilized emulsion was significantly smaller (p < 0.05) than that of the MP-stabilized emulsion with the same homogenization speed. However, polymerization of Tween 80-stabilized emulsions during the preparation of the composite gels was found. Composite gels with the MP-stabilized emulsions of a small droplet size showed significantly improved water-holding capacity, texture, and dynamic rheological properties. Interfacial shear rheology studies revealed that the storage modulus (G’) of the MP-stabilized emulsion composite gels was higher than that of the Tween 80-stabilized gels, and the tan δ of the MP-stabilized oil emulsion composite gels was smaller than that of the Tween 80-stabilized gels, indicating that stronger elastic gel structures were formed. These results suggested that the IPF formed in the MP-stabilized emulsion helped stabilize the oil droplets embedded in the protein gel network, and the smaller the droplet size, the more stable the composite gel. This work provides a better understanding of how oil emulsions interact with protein and affect the properties of MP–oil composite gels.
15
Pronkina, Tatiana Vasilievna. "About the influence of the forces of interaction between the droplets on the dynamics of emulsion". Yugra State University Bulletin 15, n. 1 (9 dicembre 2019): 59–65. http://dx.doi.org/10.17816/byusu20190159-65.
Testo completoAbstract (sommario):
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.
16
Leister, Nico, e Heike P. Karbstein. "Influence of Hydrophilic Surfactants on the W1–W2 Coalescence in Double Emulsion Systems Investigated by Single Droplet Experiments". Colloids and Interfaces 5, n. 2 (8 aprile 2021): 21. http://dx.doi.org/10.3390/colloids5020021.
Testo completoAbstract (sommario):
Double emulsions are a promising formulation for encapsulation and targeted release in pharmaceutics, cosmetics and food. An inner water phase is dispersed in an oil phase, which is again emulsified in a second water phase. The encapsulated inner water phase can be released via diffusion or via coalescence, neither of which is desired during storage but might be intended during application. The two interfaces in a double emulsion are stabilized by a hydrophilic and a lipophilic surfactant, to prevent the coalescence of the outer and the inner emulsion, respectively. This study focuses on the influence of the hydrophilic surfactant on the release of inner water or actives encapsulated therein via coalescence of the inner water droplet with the outer O–W2 interface. Since coalescence and diffusion are difficult to distinguish in double emulsions, single-droplet experiments were used to quantify differences in the stability of inner droplets. Different lipophilic (PGPH and PEG-30 dipolyhydroxylstearate) and hydrophilic surfactants (ethoxylates, SDS and polymeric) were used and resulted in huge differences in stability. A drastic decrease in stability was found for some combinations, while other combinations resulted in inner droplets that could withstand coalescence longer. The destabilization effect of some hydrophilic surfactants depended on their concentration, but was still present at very low concentrations. A huge spread of the coalescence time for multiple determinations was observed for all formulations and the necessary statistical analysis is discussed in this work. The measured stabilities of single droplets are in good accordance with the stability of double emulsions for similar surfactant combinations found in literature. Therefore, single droplet experiments are suggested for a fast evaluation of potentially suitable surfactant combinations for future studies on double-emulsion stability.
17
Shakya, Gazendra, Samuel E. Hoff, Shiyi Wang, Hendrik Heinz, Xiaoyun Ding e Mark A. Borden. "Vaporizable endoskeletal droplets via tunable interfacial melting transitions". Science Advances 6, n. 14 (aprile 2020): eaaz7188. http://dx.doi.org/10.1126/sciadv.aaz7188.
Testo completoAbstract (sommario):
Liquid emulsion droplet evaporation is of importance for various sensing and imaging applications. The liquid-to-gas phase transformation is typically triggered thermally or acoustically by low–boiling point liquids, or by inclusion of solid structures that pin the vapor/liquid contact line to facilitate heterogeneous nucleation. However, these approaches lack precise tunability in vaporization behavior. Here, we describe a previously unused approach to control vaporization behavior through an endoskeleton that can melt and blend into the liquid core to either enhance or disrupt cohesive intermolecular forces. This effect is demonstrated using perfluoropentane (C5F12) droplets encapsulating a fluorocarbon (FC) or hydrocarbon (HC) endoskeleton. FC skeletons inhibit vaporization, whereas HC skeletons trigger vaporization near the rotator melting transition. Our findings highlight the importance of skeletal interfacial mixing for initiating droplet vaporization. Tuning molecular interactions between the endoskeleton and droplet phase is generalizable for achieving emulsion or other secondary phase transitions, in emulsions.
18
Trivana, Linda, Nugraha E. Suyatma, Dase Hunaefi e S. Joni Munarso. "Effect of Surfactant Addition on The Physico-Chemical Properties and Stability of Virgin Coconut Oil Nanoemulsions". Buletin Palma 22, n. 1 (30 giugno 2021): 31. http://dx.doi.org/10.21082/bp.v22n1.2021.31-42.
Testo completoAbstract (sommario):
<p>Virgin coconut oil (VCO) is high quality coconut oil and categorized as the healthiest oil and functional foods. Based on these benefits, the development of a VCO in emulsion product might increase the human consumption of coconut oil because consumers dislike the only taste of pure VCO. The aim of this study was to develop the water compatible form of VCO through nano-emulsification. The effect of different types and amounts of surfactants (Tween 80 and Span 80) on the physio-chemical characteristic of emulsion containing VCO was investigated. VCO based emulsions were prepared with the aid of Ultra-Turrax homogenizer. Emulsions were developed by adding and mixing VCO with surfactants. The ratio of Tween 80 and Span 80 used were 0:10, 2.5:7.5, 5:5, 7.5:2.5, and 10:0. The droplet size of nanoemulsions consisting of Tween 80:Span 80 (0:10, 2.5:7.5, 5:5, 7.5:2.5, and 10:0) were 1.343, 0.606, 0.829, 1.439, and 2.506µm, respectively. Based on the TEM analysis and polydispersity index (PDI) >0.5 showed the oil droplets are in not uniform shape, indicating a unstable emulsion. VCO emulsion with ratio Tween 80:Span 80 (0:10) obtained a homogeneous emulsion (stable) compare than that of others and w/o type emulsion. The stability of emulsion is evaluated by turbidity measurement using UV-VIS spectrophotometer with wavelength 502 nm. A combination of treatments (ambient condition, thermal treatmeant (40°C)), and centrifuge) of VCO emulsion has resulted on thermal treat, the turbidity measured from the emulsion was higher than the other emulsion, reflecting the presence of the smaller droplets in this emulsion.</p>
19
Xu, Weili, Yang Yang, Sophia Xue, John Shi, Loong-Tak Lim, Charles Forney, Guihua Xu e Bio Bamba. "Effect of In Vitro Digestion on Water-in-Oil-in-Water Emulsions Containing Anthocyanins from Grape Skin Powder". Molecules 23, n. 11 (29 ottobre 2018): 2808. http://dx.doi.org/10.3390/molecules23112808.
Testo completoAbstract (sommario):
The effects of in vitro batch digestion on water-in-oil-in-water (W/O/W) double emulsions encapsulated with anthocyanins (ACNs) from grape skin were investigated. The double emulsions exhibited the monomodal distribution (d = 686 ± 25 nm) showing relatively high encapsulation efficiency (87.74 ± 3.12%). After in vitro mouth digestion, the droplet size (d = 771 ± 26 nm) was significantly increased (p < 0.05). The double W1/O/W2 emulsions became a single W1/O emulsion due to proteolysis, which were coalesced together to form big particles with significant increases (p < 0.01) of average droplet sizes (d > 5 µm) after gastric digestion. During intestinal digestion, W1/O droplets were broken to give empty oil droplets and released ACNs in inner water phase, and the average droplet sizes (d < 260 nm) decreased significantly (p < 0.05). Our results indicated that ACNs were effectively protected by W/O/W double emulsions against in vitro mouth digestion and gastric, and were delivered in the simulated small intestine phase.
20
Cho, Yu-Jin, Dong-Min Kim, In-Ho Song, Ju-Young Choi, Seung-Won Jin, Beom-Jun Kim, Jin-Won Jeong, Chae-Eun Jang, Kunmo Chu e Chan-Moon Chung. "An Oligoimide Particle as a Pickering Emulsion Stabilizer". Polymers 10, n. 10 (27 settembre 2018): 1071. http://dx.doi.org/10.3390/polym10101071.
Testo completoAbstract (sommario):
A pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA)-based oligoimide (PMDA-ODA) was synthesized by a one-step procedure using water as a solvent. The PMDA-ODA particles showed excellent partial wetting properties and were stably dispersed in both water and oil phases. A stable dispersion was not obtained with comparison PMDA-ODA particles that were synthesized by a conventional two-step method using an organic solvent. Both oil-in-water and water-in-oil Pickering emulsions were prepared using the oligoimide particles synthesized in water, and the size of the emulsion droplet was controlled based on the oligoimide particle concentration. The oligoimide particles were tested to prepare Pickering emulsions using various kinds of oils. The oil-in-water Pickering emulsions were successfully applied to prepare microcapsules of the emulsion droplets. Our new Pickering emulsion stabilizer has the advantages of easy synthesis, no need for surface modification, and the capability of stabilizing both oil-in-water and water-in-oil emulsions.
21
Liu, Fei, Yanling Wang, Xiaqing Li, Zhaoxiang Zhang, Xiaodong Dai, Xuewu Wang, Yanping Xin et al. "The phase inversion mechanism of the pH-sensitive reversible invert emulsion from w/o to o/w". Open Physics 18, n. 1 (28 luglio 2020): 380–90. http://dx.doi.org/10.1515/phys-2020-0112.
Testo completoAbstract (sommario):
AbstractAlteration in the environmental conditions will cause a reversed reaction between o/w emulsion and w/o emulsion that has similar advantages of different liquids form on the reversible invert emulsion. The reversible phase inversion of the emulsion has a benefit of dealing with drilling cutting, so the reversible invert emulsion also can be thought used as a drilling fluid. The phase inversion from w/o emulsion to o/w emulsion can be divided into three stages. They are w/o emulsion, w/o/w emulsion, and o/w emulsion. In the w/o emulsion stage, the structure appeared among water droplets when the percentage of the HCl solution (5%) was less than 0.375%. In the w/o/w emulsion stage, the structure among water droplets existed at the beginning of this stage; however, the internal phase and the external phase can interchange their positions during the process. In the third stage, the structures among droplets of the emulsion would be broken and the degree of the dispersion of the oil droplet in the emulsion would increase. The changes in the microstructure, conductivity, electrical stability, standing stability, and the viscosity of the emulsion, which have edified among droplets in the process from w/o emulsion to o/w emulsion, were studied. The result of the microstructure microscopic observation agrees with the result of the electrical stability and viscosity experiments. Moreover, the internal phase and the external phase can interchange positions during the process.
22
Li, Ze Fu, Lin Zhang, Xuan Luo, Xiao Jun Wang e Yi Yang. "Simulation of Droplets Formation in Co-Flowing Microfluidic Channels". Applied Mechanics and Materials 513-517 (febbraio 2014): 4180–84. http://dx.doi.org/10.4028/www.scientific.net/amm.513-517.4180.
Testo completoAbstract (sommario):
Emulsion droplets or multi-emulsion droplet formation was important for functional materials synthesizing by microfluidic. To obtain tunable monodisperse droplets with millimeter scale, the flow regime in co-flowing channels was divided by numerical simulation. A typical co-flowing model was created using finite volume method, and the VOF (volume of fluid) muti-phase model was selected. Then, droplets were produced by changing the velocity ratio under the dripping regime. Compared to the experimental value of droplet diameter, theoretical and numerical absolute error was below 60 % and 15 %, separately. Greet agreement of diameter changing tendency was found in simulation and experiment.
23
Lin, Cherng-Yuan, Chein-Ming Lin e Che-Shiung Cheng. "An Experimental Investigation of Burning Droplets of Emulsified Marine Fuel Oils with Water". Journal of Ship Research 39, n. 01 (1 marzo 1995): 95–101. http://dx.doi.org/10.5957/jsr.1995.39.1.95.
Testo completoAbstract (sommario):
An experimental investigation is presented of the influences of emulsification of marine fuel oils A and C with water on the micro-explosion phenomenon and combustion characteristics of a burning droplet. The amount of surfactant and water-to-oil ratio by volume in the emulsion are varied to observe the variations of ignition delay, flame length, time required to attain the maximum flame length, duration as well as intensity of micro-explosion, flame appearance, and overall burning time. The measurements show that the emulsification effects on the combustion of marine fuel oils A and C are different. A droplet of C-oil emulsion is shown to be influenced by the addition of water and surfactant more significantly. The micro-explosion phenomena of droplets of A-and C-oil emulsions are seen to occur after and before their ignition, respectively. In addition, separate combinations of water and surfactant content exist for these fuel oils to achieve better emulsification effects on combustion. Droplets of emulsions with W/O = 15/85, E% = 2% for fuel oil A and W/O = 25/75, E% = 1% for fuel oil C are found to have the most violent droplet-disruption phenomenon and the longest flame length.
24
A. Ismael, Mhadi, Morgan Heikal, A. A. Aziz, Cyril Crua, Mohmmed El-Adawy, Zuhaib Nissar, Masri Baharom, Ezrann Zainal A. e Firmansyah. "Investigation of Puffing and Micro-Explosion of Water-in-Diesel Emulsion Spray Using Shadow Imaging". Energies 11, n. 9 (30 agosto 2018): 2281. http://dx.doi.org/10.3390/en11092281.
Testo completoAbstract (sommario):
Water-in-diesel emulsions potentially favor the occurrence of micro-explosions when exposed to elevated temperatures, thereby improving the mixing of fuels with the ambient gas. The distributions and sizes of both spray and dispersed water droplets have a significant effect on puffing and micro-explosion behavior. Although the injection pressure is likely to alter the properties of emulsions, this effect on the spray flow puffing and micro-explosion has not been reported. To investigate this, we injected a fuel spray using a microsyringe needle into a high-temperature environment to investigate the droplets’ behavior. Injection pressures were varied at 10% v/v water content, the samples were imaged using a digital microscope, and the dispersed droplet size distributions were extracted using a purpose-built image processing algorithm. A high-speed camera coupled with a long-distance microscope objective was then used to capture the emulsion spray droplets. Our measurements indicated that the secondary atomization was significantly affected by the injection pressure which reduced the dispersed droplet size and hence caused a delay in puffing. At high injection pressure (500, 1000, and 1500 bar), the water was evaporated during the spray and although there was not enough droplet residence time, puffing and micro-explosion were clearly observed. This study suggests that high injection pressures have a detrimental effect on the secondary atomization of water-in-diesel emulsions.
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Francke, Nadine Monika, Frederic Schneider, Knut Baumann e Heike Bunjes. "Formulation of Cannabidiol in Colloidal Lipid Carriers". Molecules 26, n. 5 (8 marzo 2021): 1469. http://dx.doi.org/10.3390/molecules26051469.
Testo completoAbstract (sommario):
In this study, the general processability of cannabidiol (CBD) in colloidal lipid carriers was investigated. Due to its many pharmacological effects, the pharmaceutical use of this poorly water-soluble drug is currently under intensive research and colloidal lipid emulsions are a well-established formulation option for such lipophilic substances. To obtain a better understanding of the formulability of CBD in lipid emulsions, different aspects of CBD loading and its interaction with the emulsion droplets were investigated. Very high drug loads (>40% related to lipid content) could be achieved in emulsions of medium chain triglycerides, rapeseed oil, soybean oil and trimyristin. The maximum CBD load depended on the type of lipid matrix. CBD loading increased the particle size and the density of the lipid matrix. The loading capacity of a trimyristin emulsion for CBD was superior to that of a suspension of solid lipid nanoparticles based on trimyristin (69% vs. 30% related to the lipid matrix). In addition to its localization within the lipid core of the emulsion droplets, cannabidiol was associated with the droplet interface to a remarkable extent. According to a stress test, CBD destabilized the emulsions, with phospholipid-stabilized emulsions being more stable than poloxamer-stabilized ones. Furthermore, it was possible to produce emulsions with pure CBD as the dispersed phase, since CBD demonstrated such a pronounced supercooling tendency that it did not recrystallize, even if cooled to −60 °C.
26
A, Acero-Lopez, Schell P, Corredig M e Alexander M. "Characterization of lactoferrin oil-in-water emulsions and their stability in recombined milk". Journal of Dairy Research 77, n. 4 (8 settembre 2010): 445–51. http://dx.doi.org/10.1017/s0022029910000622.
Testo completoAbstract (sommario):
Emulsions were prepared with 20% soy oil and different concentrations of lactoferrin, and tested at pH values from 3 to 7·5. The stability of the emulsions decreased as the pH got closer to the isoelectric point of the protein. A concentration of 1% lactoferrin was determined to be sufficient to provide full coverage of the emulsion droplets. Lactoferrin-stabilized emulsions were then prepared in water at pH 6·6 and their behaviour when added to reconstituted milk was studied. It was observed that lactoferrin emulsions were stable when reconstituted in milk, but they showed aggregation when diluted in milk serum alone. The destabilization was caused by shielding of the charges on the surface of the oil droplets. Stabilization in milk occurred due to interactions at the interface with other soluble proteins. In fact, when β-lactoglobulin or sodium caseinate were added to the serum, stability of the emulsion droplets was restored, indicating that these proteins were able to adsorb at the interface and aid in the stabilization. Since ζ-potential measurements did not show significant overall charge on the emulsion droplets, this suggests that the stabilization forces are not only electrostatic in nature, but that there are other mechanisms at play.
27
Souza, Clitor Junior Fernandes de, e Edwin Elard Garcia Rojas. "Emulsion of systems containing egg yolk, polysaccharides and vegetable oil". Ciência e Agrotecnologia 36, n. 5 (ottobre 2012): 543–50. http://dx.doi.org/10.1590/s1413-70542012000500007.
Testo completoAbstract (sommario):
This work characterizes the emulsifying properties of systems containing egg yolk (0.1; 1.0 and 2.5 % w/v) and polysaccharides (xanthan gum, carrageen, pectin and carboxymethylcellulose) and three different vegetable oils (sunflower, canola, and palm oils). Emulsifying activity and emulsion stability were measured of each combination and it was found the effect of the oil on emulsion stability correlated to the amount of monounsaturated fatty acid. Additionally, increased egg yolk concentration increased emulsifying activity by reducing coalescence of oil droplets. Lastly, 2.5% egg yolk and 0.2% polysaccharide generated emulsions with high emulsifying activity, excellent stability, and droplet size of 4.32 µm.
28
Murphy, Ryan, Lijie Zhu, Ganesan Narsimhan e Owen Jones. "Impacts of Size and Deformability of β-Lactoglobulin Microgels on the Colloidal Stability and Volatile Flavor Release of Microgel-Stabilized Emulsions". Gels 4, n. 3 (15 settembre 2018): 79. http://dx.doi.org/10.3390/gels4030079.
Testo completoAbstract (sommario):
Emulsions can be prepared from protein microgel particles as an alternative to traditional emulsifiers. Prior experiments have indicated that smaller and more deformable microgels would decrease both the physical destabilization of emulsions and the diffusion-based losses of entrapped volatile molecules. The microgels were prepared from β-lactoglobulin with an average diameter of 150 nm, 231 nm, or 266 nm; large microgels were cross-linked to decrease their deformability. Dilute emulsions of 15–50 μm diameter were prepared with microgels by high shear mixing. Light scattering and microscopy showed that the emulsions prepared with larger, untreated microgels possessed a larger initial droplet size, but were resistant to droplet growth during storage or after acidification, increased ionic strength, and exposure to surfactants. The emulsions prepared with cross-linked microgels emulsions were the least resistant to flocculation, creaming, and shrinkage. All emulsion droplets shrank as limonene was lost during storage, and the inability of microgels to desorb caused droplets to become non-spherical. The microgels were not displaced by Tween 20 but were displaced by excess sodium dodecyl sulfate. Hexanol diffusion and associated shrinkage of pendant droplets was not prevented by any of the microgels, yet the rate of shrinkage was reduced with the largest microgels.
29
Elbing, E., AG Parts, CJ Lyons, BAW Coller e IR Wilson. "Miniemulsions of Vinyl Stearate. II. Light-Scattering Studies During the Polymerization". Australian Journal of Chemistry 42, n. 12 (1989): 2085. http://dx.doi.org/10.1071/ch9892085.
Testo completoAbstract (sommario):
The course of the polymerization of vinyl stearate has been followed by dilatometry and by light scattering. Kinetically stable and visually clear or at most opalescent 'miniemulsions' were used to minimize the scattering (otherwise large) by emulsion droplets. Light-scattering results demonstrate that the final particle size of the latexes may be greater or less than that of the emulsion droplets in the starting miniemulsion. This suggests that polymer particles are nucleated from the aqueous (micelle-containing) phase, and grow by transport of vinyl stearate monomer through the aqueous medium from the emulsion droplets to feed polymerization in the particles. Thus the droplets gradually decrease in size and disappear when all the monomer has been taken up by absorption into micelles or into growing particles. A previously proposed droplet-particle collision theory does not appear to be necessary.
30
Jans, Alexander, Jonas Lölsberg, Abdolrahman Omidinia-Anarkoli, Robin Viermann, Martin Möller, Laura De Laporte, Matthias Wessling e Alexander J. C. Kuehne. "High-Throughput Production of Micrometer Sized Double Emulsions and Microgel Capsules in Parallelized 3D Printed Microfluidic Devices". Polymers 11, n. 11 (15 novembre 2019): 1887. http://dx.doi.org/10.3390/polym11111887.
Testo completoAbstract (sommario):
Double emulsions are useful geometries as templates for core-shell particles, hollow sphere capsules, and for the production of biomedical delivery vehicles. In microfluidics, two approaches are currently being pursued for the preparation of microfluidic double emulsion devices. The first approach utilizes soft lithography, where many identical double-flow-focusing channel geometries are produced in a hydrophobic silicone matrix. This technique requires selective surface modification of the respective channel sections to facilitate alternating wetting conditions of the channel walls to obtain monodisperse double emulsion droplets. The second technique relies on tapered glass capillaries, which are coaxially aligned, so that double emulsions are produced after flow focusing of two co-flowing streams. This technique does not require surface modification of the capillaries, as only the continuous phase is in contact with the emulsifying orifice; however, these devices cannot be fabricated in a reproducible manner, which results in polydisperse double emulsion droplets, if these capillary devices were to be parallelized. Here, we present 3D printing as a means to generate four identical and parallelized capillary device architectures, which produce monodisperse double emulsions with droplet diameters in the range of 500 µm. We demonstrate high throughput synthesis of W/O/W and O/W/O double emulsions, without the need for time-consuming surface treatment of the 3D printed microfluidic device architecture. Finally, we show that we can apply this device platform to generate hollow sphere microgels.
31
Ng, Siou Pei, Yih Phing Khor, Hong Kwong Lim, Oi Ming Lai, Yong Wang, Yonghua Wang, Ling Zhi Cheong, Imededdine Arbi Nehdi, Lamjed Mansour e Chin Ping Tan. "Fabrication of Concentrated Palm Olein-Based Diacylglycerol Oil–Soybean Oil Blend Oil-In-Water Emulsion: In-Depth Study of the Rheological Properties and Storage Stability". Foods 9, n. 7 (3 luglio 2020): 877. http://dx.doi.org/10.3390/foods9070877.
Testo completoAbstract (sommario):
The present study focused on investigating the storage stability of oil-in-water (O/W) emulsions with high oil volume fractions prepared with palm olein-based diacylglycerol oil (POL-DAG)/soybean oil (SBO) blends at 25 °C. The incorporation of different ratios of oil blends significantly influenced (p < 0.05) the texture, color, droplet size distribution, and rheological parameters of the emulsions. Only emulsions incorporated with 10% to 20% POL-DAG in oil phase exhibited pseudoplastic behavior that fitted the Power Law model well. Furthermore, the O/W emulsions prepared with POL-DAG/SBO blends exhibited elastic properties, with G’ higher than G”. During storage, the emulsion was found to be less solid-like with the increase in tan δ values. All emulsions produced with POL-DAG/SBO blends also showed thixotropic behavior. Optical microscopy revealed that the POL-DAG incorporation above 40% caused aggregated droplets to coalesce and flocculate and, thus, larger droplet sizes were observed. The current results demonstrated that the 20% POL-DAG substituted emulsion was more stable than the control emulsion. The valuable insights gained from this study would be able to generate a lot more possible applications using POL-DAG, which could further sustain the competitiveness of the palm oil industry.
32
Bielas, Rafał, e Arkadiusz Józefczak. "The Effect of Particle Shell on Cooling Rates in Oil-in-Oil Magnetic Pickering Emulsions". Materials 13, n. 21 (26 ottobre 2020): 4783. http://dx.doi.org/10.3390/ma13214783.
Testo completoAbstract (sommario):
Pickering emulsions (particle-stabilized emulsions) are usually considered because of their unique properties compared to surfactant-stabilized emulsions including better stability against emulsion aging. However, the interesting feature of particle-stabilized emulsions could be revealed during their magnetic heating. When magnetic particles constitute a shell around droplets and the sample is placed in an alternating magnetic field, a temperature increase appears due to energy dissipation from magnetic relaxation and hysteresis within magnetic particles. We hypothesize that the solidity of the magnetic particle shell around droplets can influence the process of heat transfer from inside the droplet to the surrounding medium. In this way, particle-stabilized emulsions can be considered as materials with changeable heat transfer. We investigated macroscopically heating and cooling of oil-in-oil magnetic Pickering emulsions with merely packed particle layers and these with a stable particle shell. The change in stability of the shell was obtained here by using the coalescence of droplets under the electric field. The results from calorimetric measurements show that the presence of a stable particle shell caused a slower temperature decrease in samples, especially for lower intensities of the magnetic field. The retarded heat transfer from magnetic Pickering droplets can be utilized in further potential applications where delayed heat transfer is desirable.
33
Félix, Manuel, Alberto Romero, Cecilio Carrera-Sanchez e Antonio Guerrero. "A Comprehensive Approach from Interfacial to Bulk Properties of Legume Protein-Stabilized Emulsions". Fluids 4, n. 2 (3 aprile 2019): 65. http://dx.doi.org/10.3390/fluids4020065.
Testo completoAbstract (sommario):
The correlation between interfacial properties and emulsion microstructure is a topic of special interest that has many industrial applications. This study deals with the comparison between the rheological properties of oil-water interfaces with adsorbed proteins from legumes (chickpea or faba bean) and the properties of the emulsions using them as the only emulsifier, both at microscopic (droplet size distribution) and macroscopic level (linear viscoelasticity). Two different pH values (2.5 and 7.5) were studied as a function of storage time. Interfaces were characterized by means of dilatational and interfacial shear rheology measurements. Subsequently, the microstructure of the final emulsions obtained was evaluated thorough droplet size distribution (DSD), light scattering and rheological measurements. Results obtained evidenced that pH value has a strong influence on interfacial properties and emulsion microstructure. The best interfacial results were obtained for the lower pH value using chickpea protein, which also corresponded to smaller droplet sizes, higher viscoelastic moduli, and higher emulsion stability. Thus, results put forward the relevance of the interfacial tension values, the adsorption kinetics, the viscoelastic properties of the interfacial film, and the electrostatic interactions among droplets, which depend on pH and the type of protein, on the microstructure, rheological properties, and stability of legume protein-stabilized emulsions.
34
Azarmanesh, Milad, Mousa Farhadi e Pooya Azizian. "Simulation of the double emulsion formation through a hierarchical T-junction microchannel". International Journal of Numerical Methods for Heat & Fluid Flow 25, n. 7 (7 settembre 2015): 1705–17. http://dx.doi.org/10.1108/hff-09-2014-0294.
Testo completoAbstract (sommario):
Purpose – The purpose of this paper is to present a practical way to create three kinds of double emulsions such as double emulsion, double-component double emulsion and viscoelastic double emulsion. Design/methodology/approach – A hierarchical T-junction microfluidic device is selected to simulate this phenomenon. A system of the three-phase flows consists of the inner, middle and outer phases were simulated by the direct numerical simulation (DNS) method. The dripping regime is considered for the droplet formation in both T-junctions. The adaptive mesh refinement technique is used to simulate the droplet formation and determine the interface rupture. Findings – The one-step and two-step encapsulation are used to create the double emulsion and the viscoelastic double emulsion, respectively. In both T-junctions, droplets are created by the balance of three parameters which are instability, viscous drag and pressure buildup. The one-step formation of double emulsion is presented for encapsulates the viscoelastic fluid. Originality/value – The simulated hierarchical microchannel shows some desirable features for creating the complex compounds. The encapsulation process is simulated in micro-scale that is useful for drug delivery applications.
35
Luo, Shirui, Jarrod Schiffbauer e Tengfei Luo. "Effect of cooling on droplet size in supersaturation-induced emulsions". Physical Chemistry Chemical Physics 19, n. 44 (2017): 29855–61. http://dx.doi.org/10.1039/c7cp05905a.
Testo completoAbstract (sommario):
In this work, the droplet size in a water-in-oil emulsion obtained by supersaturation is studied. The average size of water droplets in the emulsion is found to be proportional to the square root of the cooling rate.
36
Lee, Dongkyu, Hiroyuki Kitahata e Hiroaki Ito. "Fabrication of Microparticles with Front–Back Asymmetric Shapes Using Anisotropic Gelation". Micromachines 12, n. 9 (17 settembre 2021): 1121. http://dx.doi.org/10.3390/mi12091121.
Testo completoAbstract (sommario):
Droplet-based microfluidics is a powerful tool for producing monodispersed micrometer-sized droplets with controlled sizes and shapes; thus, it has been widely applied in diverse fields from fundamental science to industries. Toward a simpler method for fabricating microparticles with front–back asymmetry in their shapes, we studied anisotropic gelation of alginate droplets, which occurs inside a flow-focusing microfluidic device. In the proposed method, sodium alginate (NaAlg) aqueous phase fused with a calcium chloride (CaCl2) emulsion dispersed in the organic phase just before the aqueous phase breaks up into the droplets. The fused droplet with a front–back asymmetric shape was generated, and the asymmetric shape was kept after geometrical confinement by a narrow microchannel was removed. The shape of the fused droplet depended on the size of prefused NaAlg aqueous phase and a CaCl2 emulsion, and the front–back asymmetry appeared in the case of the smaller emulsion size. The analysis of the velocity field inside and around the droplet revealed that the stagnation point at the tip of the aqueous phase also played an important role. The proposed mechanism will be potentially applicable as a novel fabrication technique of microparticles with asymmetric shapes.
37
Pavlovic, Marko, Markus Antonietti e Lukas Zeininger. "Cascade communication in disordered networks of enzyme-loaded microdroplets". Chemical Communications 57, n. 13 (2021): 1631–34. http://dx.doi.org/10.1039/d0cc08310k.
Testo completo
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Chongprakobkit, Suchada, e Wanpen Tachaboonyakiat. "A Thermal Controlled Release of Naproxen from Sodium Phosphorylated Chitosan Nanoemulsion". Advanced Materials Research 701 (maggio 2013): 217–21. http://dx.doi.org/10.4028/www.scientific.net/amr.701.217.
Testo completoAbstract (sommario):
The aim of this research was to control the delivery of naproxen from emulsion-based sodium phosphorylated chitosan (PCTS) nanoparticles (PCTS nanoemulsion) by thermal stimulus. The dynamic light scattering and optical microscope results demonstrated that the droplet size of emulsion-based nanoparticles was sensitive to temperature. The PCTS nanoemulsion exhibited the droplet size around 230 nm at 30°C. Emulsion droplets were increased in their size over critical temperature of around 60°C. Besides, the droplet size was reversible to 270 nm when the temperature decreased to 30°C. This indicated that the droplet size of PCTS nanoemulsion was sensitive to thermal stimulus. It might owe to molecular chain extension and rearrangement of PCTS at the interface of emulsion droplets. Therefore, the control release of naproxen from PCTS nanoemulsion via thermal stimulus was investigated.In vitrorelease study showed that the naproxen was released from PCTS nanoemulsion in high amount over critical temperature. These results indicated that the PCTS nanoemulsion exhibited a potential application as intelligent thermal sensitive drug carrier.
39
Bawazer, Lukmaan A., Ciara S. McNally, Christopher J. Empson, William J. Marchant, Tim P. Comyn, Xize Niu, Soongwon Cho et al. "Combinatorial microfluidic droplet engineering for biomimetic material synthesis". Science Advances 2, n. 10 (ottobre 2016): e1600567. http://dx.doi.org/10.1126/sciadv.1600567.
Testo completoAbstract (sommario):
Although droplet-based systems are used in a wide range of technologies, opportunities for systematically customizing their interface chemistries remain relatively unexplored. This article describes a new microfluidic strategy for rapidly tailoring emulsion droplet compositions and properties. The approach uses a simple platform for screening arrays of droplet-based microfluidic devices and couples this with combinatorial selection of the droplet compositions. Through the application of genetic algorithms over multiple screening rounds, droplets with target properties can be rapidly generated. The potential of this method is demonstrated by creating droplets with enhanced stability, where this is achieved by selecting carrier fluid chemistries that promote titanium dioxide formation at the droplet interfaces. The interface is a mixture of amorphous and crystalline phases, and the resulting composite droplets are biocompatible, supporting in vitro protein expression in their interiors. This general strategy will find widespread application in advancing emulsion properties for use in chemistry, biology, materials, and medicine.
40
N. A., M. Mukhtar, Abd Rashid Abd Aziz, Ftwi Y. Hagos, M. M. Noor, Kumaran Kadirgama, Rizalman Mamat e A. Adam Abdullah. "The Influence of Formulation Ratio and Emulsifying Settings on Tri-Fuel (Diesel–Ethanol–Biodiesel) Emulsion Properties". Energies 12, n. 9 (6 maggio 2019): 1708. http://dx.doi.org/10.3390/en12091708.
Testo completoAbstract (sommario):
In this study, an alternative fuel for compression ignition (CI) engines called tri-fuel emulsion was prepared using an ultrasonic emulsifier. The objective of the study is to investigate the effect of emulsifying settings and formulation ratio on the physicochemical properties of tri-fuel emulsions. Design of experiment (DOE) with the two-level factorial design was employed to analyze the effect of emulsifying settings such as time, amplitude, and cycle along with the variation ratio of tri-fuel emulsion components as control factors. Numbers of responses identified were important parameters that may contribute to microexplosion phenomenon in CI engine. Analysis of variance (ANOVA) was carried out for each response, and the results indicated that density, dynamic viscosity, surface tension, and average droplet size were influenced by specific preparation control factors. Furthermore, interaction among the control factors was found to affect the responses as well. Interaction means the effect of two factors together is different than what would be expected from each factor separately. Besides, the stability of the tri-fuel emulsion was observed for three months. Furthermore, a qualitative approach with a multiobjective lens digital microscope revealed the geometry of freshly made dispersed tri-fuel emulsion droplets. Microscopic examination on tri-fuel emulsion droplets has shown that the dispersed ethanol capsulated within diesel with the help of biodiesel is similar to a water in diesel emulsion and is dissimilar to commercial diesel mixed with fatty acid methyl esters found in the market.
41
Chung, Casper Ho Yin, Binbin Cui, Ruyuan Song, Xin Liu, Xiaonan Xu e Shuhuai Yao. "Scalable Production of Monodisperse Functional Microspheres by Multilayer Parallelization of High Aspect Ratio Microfluidic Channels". Micromachines 10, n. 9 (10 settembre 2019): 592. http://dx.doi.org/10.3390/mi10090592.
Testo completoAbstract (sommario):
Droplet microfluidics enables the generation of highly uniform emulsions with excellent stability, precise control over droplet volume, and morphology, which offer superior platforms over conventional technologies for material synthesis and biological assays. However, it remains a challenge to scale up the production of the microfluidic devices due to their complicated geometry and long-term reliability. In this study, we present a high-throughput droplet generator by parallelization of high aspect ratio rectangular structures, which enables facile and scalable generation of uniform droplets without the need to precisely control external flow conditions. A multilayer device is formed by stacking layer-by-layer of the polydimethylsiloxane (PDMS) replica patterned with parallelized generators. By feeding the sample fluid into the device immersed in the carrying fluid, we used the multilayer device with 1200 parallelized generators to generate monodisperse droplets (~45 μm in diameter with a coefficient of variation <3%) at a frequency of 25 kHz. We demonstrate this approach is versatile for a wide range of materials by synthesis of polyacrylamide hydrogel and Poly (l-lactide-co-glycolide) (PLGA) through water-in-oil (W/O) and oil-in-water (O/W) emulsion templates, respectively. The combined scalability and robustness of such droplet emulsion technology is promising for production of monodisperse functional materials for large-scale applications.
42
Nagelberg, Sara, Amy Goodling, Kaushikaram Subramanian, George Barbastathis, Moritz Kreysing, Tim Swager, Lauren Zarzar e 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.
Testo completoAbstract (sommario):
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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TOUZOUIRT, Saida, Fetta KESSAL, Chanez BELAIDI e Dihia BOULHALFA. "INFLUENCE OF PROCESSING PARAMETERS ON RHEOLOGICAL BEHAVIOR OF BENTONITE-BASED PICKERING EMULSION". Journal of Drug Delivery and Therapeutics 8, n. 5 (12 settembre 2018): 442–47. http://dx.doi.org/10.22270/jddt.v8i5.1903.
Testo completoAbstract (sommario):
The aim of this work is to study the impact of processing parameters on the rheological properties of Pickering emulsions containing bentonite particles, CTAB, NaCl and soybean oil. Emulsification experiments were performed using mixing and homogenization at different speeds for 10 minutes. The effects of stirring speed and homogenization were investigated to determine the best conditions for producing a suitable Pickering emulsion for the intended application. In order to assess the influence of processing parameters on the Pickering emulsion rheological behavior average droplet size was measured and rheological tests were performed on all the emulsions samples. The rheological behavior of these emulsions is modeled by Casson's law. Results show that the stirring speed first decreases the average size of the droplets, and then an effect on the initial viscosity is observed. Increasing the stirring speed increases the values of the initial viscosity in contrast to the infinite viscosity which is influenced by the homogenization speed. On the other hand, these processing parameters significantly affect the values of the yield strength.
Keywords: stirring speed, speed homogenization, rheological properties, Pickering emulsion.
44
Zhang, Yin, Xiaojin He, Rebecca Zhuo, Ruojie Sha, Jasna Brujic, Nadrian C. Seeman e Paul M. Chaikin. "Multivalent, multiflavored droplets by design". Proceedings of the National Academy of Sciences 115, n. 37 (27 agosto 2018): 9086–91. http://dx.doi.org/10.1073/pnas.1718511115.
Testo completoAbstract (sommario):
Nature self-assembles functional materials by programming flexible linear arrangements of molecules and then folding them to make 2D and 3D objects. To understand and emulate this process, we have made emulsion droplets with specific recognition and controlled valence. Uniquely monovalent droplets form dimers: divalent lead to polymer-like chains, trivalent allow for branching, and programmed mixtures of different valences enable a variety of designed architectures and the ability to subsequently close and open structures. Our functional building blocks are a hybrid of micrometer-scale emulsion droplets and nanoscale DNA origami technologies. Functional DNA origami rafts are first added to droplets and then herded into a patch using specifically designated “shepherding” rafts. Additional patches with the same or different specificities can be formed on the same droplet, programming multiflavored, multivalence droplets. The mobile patch can bind to a patch on another droplet containing complementary functional rafts, leading to primary structure formation. Further binding of nonneighbor droplets can produce secondary structures, a third step in hierarchical self-assembly. The use of mobile patches rather than uniform DNA coverage has the advantage of valence control at the expense of slow kinetics. Droplets with controlled flavors and valences enable a host of different material and device architectures.
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Gunning, A. P., A. R. Mackie, P. J. Wilde e V. J. Morris. "Atomic Force Microscopy of Emulsion Droplets: Probing Droplet−Droplet Interactions". Langmuir 20, n. 1 (gennaio 2004): 116–22. http://dx.doi.org/10.1021/la034835+.
Testo completo
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Jain, N., C. K. Liu, B. S. Hawkett, G. G. Warr e 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, n. 1 (25 dicembre 2013): 41–52. http://dx.doi.org/10.1107/s1600576713030045.
Testo completoAbstract (sommario):
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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Ma, Pu, Hamiti, Wei e Chen. "Elaboration of the Demulsification Process of W/O Emulsion with Three-Dimensional Electric Spiral Plate-Type Microchannel". Micromachines 10, n. 11 (1 novembre 2019): 751. http://dx.doi.org/10.3390/mi10110751.
Testo completoAbstract (sommario):
Rapid and efficient demulsification (destabilizing of an emulsion) processes of a water in oil (W/O) emulsion were carried out in a three-dimensional electric spiral plate-type microchannel (3D-ESPM). In this experiment, the demulsifying efficiency of emulsions by 3D-ESPM was compared with that by gravity settling, the factors influencing demulsifying efficiency were investigated, and the induction period, cut size and residence time in the demulsification process were studied. The results showed that in contrast to the gravity settling method, 3D-ESPM can directly separate the disperse phase (water) instead of the continuous phase (oil). The maximum demulsifying efficiency of W/O emulsion in a single pass through the 3D-ESPM reached 90.3%, with a microchannel height of 200 μm, electric field intensity of 250 V /cm, microchannel angle of 180°, microchannel with 18 plates and a flow rate of 2 mL /min. An induction period of 0.6 s during the demulsification process was simulated with experimental data fitting. When the residence time of emulsion in 3D-ESPM was longer than the induction period, its demulsifying efficiency increased as the increase of the flow velocity due to the droplet coalescence effects of Dean vortices in the spiral microchannel. For this device a cut size of droplets of 4.5 μm was deduced. Our results showed that the demulsification process of W/O emulsion was intensified by 3D-ESPM based on the coupling effect between electric field-induced droplets migration and microfluidic hydrodynamic trapping.
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Dinache, Andra, Tatiana Tozar, Adriana Smarandache, Ionut Relu Andrei, Simona Nistorescu, Viorel Nastasa, Angela Staicu, Mihail-Lucian Pascu e Mihaela Oana Romanitan. "Spectroscopic Characterization of Emulsions Generated with a New Laser-Assisted Device". Molecules 25, n. 7 (9 aprile 2020): 1729. http://dx.doi.org/10.3390/molecules25071729.
Testo completoAbstract (sommario):
This paper presents a spectroscopic study of emulsions generated with a laser-assisted device. Fourier transform infrared (FTIR), Raman and UV–Vis–NIR reflectance spectra of emulsions, recorded before and after exposure to laser radiation were used to characterize the effect of laser irradiation. The paper also presents a comparison between the calculated IR spectra and the experimental FTIR spectra of an emulsion’s components. FTIR measurements allowed the identification of absorption bands specific to each of the emulsions’ components. Moreover, it enabled the observation of destabilization of the emulsion in real-time. Raman spectroscopy allowed the observation of the modifications at a molecular level, by identifying the vibrations of the representative functional groups and the polymerization of sodium tetradecyl sulfate (STS) molecules by analyzing the evolution of the carbonyl band. UV–Vis–NIR reflectance spectra of emulsions before and after exposure to laser radiation showed that the physical characteristics of the emulsions changed during irradiation—the dimensions of the droplets decreased, leading to an emulsion with a better time stability. These results proved that the employed spectroscopy techniques were powerful tools in emulsion analysis.
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Ruan, Da, Diliyaer Hamiti, Zheng-Dong Ma, Ya-Dong Pu e Xiao Chen. "Demulsification of Kerosene/Water Emulsion in the Transparent Asymmetric Plate-Type Micro-Channel". Micromachines 9, n. 12 (19 dicembre 2018): 680. http://dx.doi.org/10.3390/mi9120680.
Testo completoAbstract (sommario):
Asymmetric plate-type micro-channels (APM) have one hydrophobic wall and one hydrophilic wall. By flowing through APM, a kerosene-in-water emulsion can be de-emulsified in one second. To date, however, the demulsification process in the APM is still a black box. In order to observe the demulsification process directly, transparent asymmetric plate-type micro-channels (TAPM) were fabricated with two surface-modified glass plates. Emulsions with oil contents of 10%, 30%, and 50% were pumped through TAPM with heights of 39.2 μm and 159.5 μm. The movement and coalescence of oil droplets (the dispersed phase of a kerosene-in-water emulsion) in the TAPM were observed directly with an optical microscope. By analyzing videos and photographs, it was found that the demulsification process included three steps: oil droplets flowed against and were adsorbed on the hydrophobic wall, then oil droplets coalesced to form larger droplets, whereupon the oil phase was separated. The experimental results showed that the demulsification efficiency was approximately proportional to the oil content (30–50%) of the emulsions and increased when the micro-channel height was reduced.
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Masalova, Irina, e Alexander Ya Malkin. "Rheology of Highly Concentrated Emulsions – Concentration and Droplet Size Dependencies". Applied Rheology 17, n. 4 (1 agosto 2007): 42250–1. http://dx.doi.org/10.1515/arh-2007-0011.
Testo completoAbstract (sommario):
Abstract The concentration and size dependencies of elastic properties of highly concentrated w/o emulsions were studied. The range of weight concentration of the disperse phase was 90 - 96%, the range of the average droplet size was 16 - 20 mm, and the droplet size distribution remained unchanged. The disperse phase consists of droplets of over-cooled concentrated aqueous solutions of inorganic salts. The concentration range being studied lies above the limit of maximal close packing, j > jm. The droplet size distribution is fairly wide and the shape of droplets is polygonal. These factors alone determine possible new rheological effects, such as the elasticity and visco-plastic behaviour of emulsions, as well as the observed form of concentration and size dependencies of rheological properties of emulsions. The complete flow curves were measured for these fairly new emulsion systems. It emerged that they were similar to the entire concentration and droplet size ranges being studied. The concentration dependencies of the yield stress and storage modules corresponded to the Princen-Kiss theory with critical volume concentration approximately 0.71 - 0.74. However, this theory describes the size dependence of elastic modules incorrectly. A new model is proposed, which correctly describes the dependencies of elastic modules on both determining parameters - those of concentration and droplet size.