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Thomas Heinze - One of the best experts on this subject based on the ideXlab platform.
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nanoparticles from conventional cellulose esters evaluation of preparation methods
Cellulose, 2013Co-Authors: Holger Wondraczek, Katrin Petzoldwelcke, Pedro Fardim, Thomas HeinzeAbstract:Nano-scaled particles were obtained from two different cellulose acetates, cellulose acetate propionate, and cellulose acetate butyrate using the Emulsification solvent evaporation procedure and the low energy methods of solvent displacement (dialysis and controlled precipitation). The relationship between the formulation parameters and the particle properties were evaluated in case of the Emulsification-evaporation technique. For the solvent displacement procedures, the influence of the formulation parameters, and the intrinsic polymer properties like the hydrophilic-hydrophobic balance was evaluated. Comparing the methods, it could be shown that large amounts of small and uniform nanoparticles can be obtained by the Emulsification solvent evaporation procedure. The solvent displacement techniques turned out to be very easy to use and to yield narrowly distributed particles as well.
Mitsutoshi Nakajima - One of the best experts on this subject based on the ideXlab platform.
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production of uniform droplets using membrane microchannel and microfluidic Emulsification devices
Microfluidics and Nanofluidics, 2012Co-Authors: Goran T. Vladisavljevic, Mitsutoshi Nakajima, Isao KobayashiAbstract:This review provides an overview of major microengineering Emulsification techniques for production of monodispersed droplets. The main emphasis has been put on membrane Emulsification using Shirasu Porous Glass and microsieve membrane, microchannel Emulsification using grooved-type and straight-through microchannel plates, microfluidic junctions and flow focusing microfluidic devices. Microfabrication methods for production of planar and 3D poly(dimethylsiloxane) devices, glass capillary microfluidic devices and single-crystal silicon microchannel array devices have been described including soft lithography, glass capillary pulling and microforging, hot embossing, anisotropic wet etching and deep reactive ion etching. In addition, fabrication methods for SPG and microseive membranes have been outlined, such as spinodal decomposition, reactive ion etching and ultraviolet LIGA (Lithography, Electroplating, and Moulding) process. The most widespread application of micromachined Emulsification devices is in the synthesis of monodispersed particles and vesicles, such as polymeric particles, microgels, solid lipid particles, Janus particles, and functional vesicles (liposomes, polymersomes and colloidosomes). Glass capillary microfluidic devices are very suitable for production of core/shell drops of controllable shell thickness and multiple emulsions containing a controlled number of inner droplets and/or inner droplets of two or more distinct phases. Microchannel Emulsification is a very promising technique for production of monodispersed droplets with droplet throughputs of up to 100 l h−1.
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Encapsulation of Lipophilic Bioactive Molecules by Microchannel Emulsification
Food Biophysics, 2008Co-Authors: Marcos A. Neves, Isao Kobayashi, Henelyta S. Ribeiro, Mitsutoshi NakajimaAbstract:Currently, much effort is being invested in novel formulations of bioactive molecules, such as emulsions, for pharmaceutical, food, and cosmetic applications. Therefore, methods to produce emulsions with controlled-size droplets of uniform size distribution have been developed. On this concern, a microfluidic device called the microchannel (MC) was used in this work for Emulsification. This is a novel method for producing monodispersed emulsion droplets with very narrow droplet size distribution and low energy input, due to the spontaneous droplet generation basically driven by the interfacial tension, unlike other conventional Emulsification processes. This technology provides the formulation of oil-in-water (O/W) emulsions containing lipophilic active molecules with increased bioavailability, which may be readily absorbed by the human body. MC Emulsification enables the preparation of highly monodispersed O/W emulsions, which may be applied as enhancer on active molecules delivery systems, as well as in foodstuff. In this study, formulations of O/W emulsions loaded with bioactive molecules, such as β-carotene and γ-oryzanol, were prepared by the MC Emulsification process. Refined soybean oil containing the dissolved lipophilic molecule and either sugar ester or gelatin solution (1 wt.%) were used as the dispersed and continuous phases, respectively. The Emulsification process conducted using the asymmetric straight-through MC plate enabled the production of monodispersed O/W emulsions, resulting in β-carotene-loaded O/W emulsions with average droplet size (dav) of 27.6 μm and coefficient of variation (CV) of 2.3% and γ-oryzanol-loaded droplets with dav of 28.8 μm and CV of 3.8%. The highly monodisperse β-carotene-loaded droplets were physically stable throughout the storage period observed, resulting in droplets with dav 28.2 μm and CV of 2.9% after 4 months storage in darkness at 5 °C. Single micrometer-sized monodisperse emulsions loaded with β-carotene were successfully formulated using the grooved MC Emulsification, resulting in droplets with dav of 9.1 μm and CV of 6.2%.
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characterization of spontaneous transformation based droplet formation during microchannel Emulsification
Journal of Physical Chemistry B, 2002Co-Authors: Shinji Sugiura, Mitsutoshi Nakajima, Naoyuki Kumazawa, And Satoshi Iwamoto, Minoru SekiAbstract:Recently, we proposed a microchannel (MC) Emulsification technique, which is a novel method for making a monodispersed emulsion from a microfabricated channel array. The droplet formation mechanism for MC Emulsification is a unique one, in which the distorted dispersed phase is spontaneously transformed into spherical droplets by interfacial tension. The objective of this study was to characterize the flow in MC Emulsification. We investigated the Emulsification behavior at different flow velocities of the dispersed phase using MCs with different sizes and analogous shapes and found a critical flow velocity over which the character of flow changed drastically. The formed droplet diameters were almost constant below the critical velocity, and monodispersed emulsions were formed. The droplet diameters increased drastically above the critical velocity, and polydispersed emulsions were formed. The critical velocities were independent of MC size. Analysis using a dimensionless number revealed that the critical...
Roozbeh Rafati - One of the best experts on this subject based on the ideXlab platform.
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effect of ultrasound radiation duration on Emulsification and dEmulsification of paraffin oil and surfactant solution brine using hele shaw models
Ultrasonics Sonochemistry, 2015Co-Authors: Hossein Hamidi, Erfan Mohammadian, Mohammad Asadullah, Amin Azdarpour, Roozbeh RafatiAbstract:Abstract Ultrasound technique is one of the unconventional enhanced oil recovery methods which has been of interest for more than six decades. However, the majority of the oil recovery mechanisms under ultrasound reported in the previous studies are theoretical. Emulsification is one of the mechanisms happening at the interface of oil and water in porous media under ultrasound. Oppositely, ultrasound is one of the techniques using in oil industry for dEmulsification of oil/water emulsion. Therefore, the conditions in which Emulsification becomes dominant over dEmulsification under ultrasound should be more investigated. Duration of ultrasound radiation could be one of the factors affecting Emulsification and dEmulsification processes. In this study a technique was developed to investigate the effect of long and short period of ultrasound radiation on Emulsification and dEmulsification of paraffin oil and surfactant solution in porous media. For this purpose, the 2D glass Hele-shaw models were placed inside the ultrasonic bath under long and short period of radiation of ultrasound. A microscope was used above the model for microscopic studies on the interface of oil and water. Diffusion of phases and formation of emulsion were observed in both long and short period of application of ultrasound at the beginning of ultrasound radiation. However, by passing time, dEmulsification and coalescence of brine droplets inside emulsion was initiated in long period of ultrasound application. Therefore, it was concluded that Emulsification could be one of the significant oil recovery mechanisms happening in porous media under short period of application of ultrasound.
Martin B G Jun - One of the best experts on this subject based on the ideXlab platform.
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use of vegetable oil in water emulsion achieved through ultrasonic atomization as cutting fluids in micro milling
Journal of Manufacturing Processes, 2014Co-Authors: Geoff Burton, Chanseo Goo, Yanqiao Zhang, Martin B G JunAbstract:Abstract Significant amount of work is reported on development of vegetable oil based metalworking fluids (MWFs). Many also report on development and performance evaluation of vegetable based oils. For many of these water-based MWFs with vegetable oils, much effort is focused on stable Emulsification of vegetable oil in water using a variety of surfactants. It has been found that surfactant-free stable Emulsification of oil in water is possible through ultrasonic vibration. However, Emulsification through ultrasonic atomization has not yet been considered, and the feasibility of emulsified metalworking fluids through ultrasonic atomization has not been investigated. In this paper, stable Emulsification of vegetable oil in water has been achieved through ultrasonic atomization without using any surfactant. The emulsified vegetable oil in water is directly used to investigate its effectiveness as MWF in milling operations. Lower cutting forces, chip thickness, and burr amount are observed with vegetable oil-in-water emulsion compared to conventional MWF. The experimental results show strong potential for vegetable oil-in-water emulsion obtained through ultrasonic atomization as an effective MWF.
Xing Huang - One of the best experts on this subject based on the ideXlab platform.
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electro coalescence in step Emulsification dynamics and applications
Lab on a Chip, 2020Co-Authors: Xing Huang, Hao Pei, Yun Jie RuanAbstract:Step Emulsification is a low-shear method to produce monodispersed microdroplets by spontaneous breakup of dispersed fluid at a spatial “step”. As a semi-open microfluidic system, controllable coalescence of multiple components in step Emulsification has not been achieved. Here, we use a low voltage to control the coalescence position of flow tips in the terrace. By investigating the interaction between the coalescence behavior and the hydrodynamics of the drop formation, we numerically predict the shape evolution of the flow tips and give a semi-empirical model to calculate the sizes of droplets by the flow rates and the voltage. Furthermore, we explore the capabilities of the electro-coalescer based on step Emulsification. To trigger the coalescence in the wide reservoir, the clogging problem in precipitate-producing reactions is avoided. Besides, the low-shear nature of step Emulsification also facilitates the production of multilayered droplets.