Quasi-emulsions

Note The operations described above are applicable to any single-base proplnt. In order to prepare a double-base proplnt, the required amt of NG(or NG + NGc) in a suitable solvent is added at this stage of the process and dispersed uniformly throughout the quasi-emulsion. Substances like DNT, TNT, DBuPh, centralites, etc may be incorporated, if desired in the same manner as NG... 

Re, M.I., Biscans, B., 1999. Preparation of microsphere of ketoprofen with acrylic polymers by a quasi emulsion solvent diffusion method. Powder Technology 101 (2), 120—133. 

Kawashima Y, Niwa T, Handa T, Takeuchi H, Iwamoto T, Itoh K. Preparation of controlled-release microspheres of ibuprofen with acrylic polymers by a novel quasi-emulsion solvent diffusion method. Journal of Pharmaceutical Sciences. January 1989 78(1) 68-72. PubMed PMID 2709323. 

Espitalier, F., Biscans, B., Authelin, J-R. and Laguerie, C. (1997) Modelling of the mechanism of formation of spherical grains obtained by the quasi-emulsion crystallization process. Chemical Engineering Research and Design, 75, 251-161. 

Spherical agglomeration has got more importance than other methods because it is easy to operate and the selection of the solvents is easier than in the other methods. Quasi emulsion solvent diffusion method has the second importance. 

Tapas, A.R., Kawtikwar, P.S., Sakarkar, D.M. (2009). Enhanced dissolution rate of felodipine using spherical agglomeration with Inutec SPT by quasi emulsion solvent diffusion method. Research in Pharmaceutical Sciences, 4, 77-84. 

Details are given of the preparation of nanoparticle suspensions of ethyl acrylate-methyl methacrylate copolymers and loaded with flurbiprofen. The availability of the drug at an intra-ocular level for the prevention of the myosis induced during extracapsular cataract surgery was investigated. Nanosuspensions were prepared by a quasi-emulsion solvent diffusion technique using different formulation parameters. 34 refs. 

The bubbles play the role of the gas phase. The role of the liquid is played by an emulsion phase that consists of solid particles and suspending gas in a configuration similar to that at incipient fluidization. The quasi-phases are in cocurrent flow, with mass transfer between the phases and with a solid-catalyzed reaction occurring only in the emulsion phase. The downward flow of solids that occurs near the walls is not explicitly considered in this simplified model. 

C. Goubault, K. Pays, D. Olea, J. Bibette, V. Schmitt, and E. Leal-Calderon Shear Rupturing of Complex Fluids Application to the Preparation of Quasi-Monodisperse W/OAV Double Emulsions. Langmuir 17, 5184 (2001). 

Figure 6.2 represents the behavior of quasi-monodisperse double emulsions in (C , (pf) coordinates, where (pf is the initial volume fraction of droplets in the globules. Sorbitan monooleate (SMO) was used for the stabilization of the primary W/O emulsion and sodium dodecyl sulfate (SDS, CMC = 8 10 mol/1) was used for the stabilization of the oil globules in the external aqueous phase. Three different compositions zones, referred to as A, B, and C can be defined they differ by their qualitative behavior observed via microscopy. Moderate internal droplet volume fractions are considered first (cpf < 20%). If Ck = CMC/10, the system does not exhibit any structural evolution after a few days of storage (zone A). If C is... 

Figure 6.2. Behavior of a quasi-monodisperse double emulsion as a function of the two composition parameters C/, and

In Zerrouki s experiments, the preparation of aqueous phases of identical clusters is performed in six steps. First, colloidal particles of silica, 1.2 pm in diameter, are synthesized. Next, the surface of the particles is made hydrophobic by chemical grafting. Then, an oil-in-water premix emulsion is made by adding an octane suspension of the colloids in an aqueous solution. Controlled shear of the premix in a Couette-type apparatus is subsequently performed to obtain a quasi-monodisperse... 

FIGURE 35 Emulsified liquid membrane separation mechanisms (A) selective permeation (B) chemical reaction inside emulsion droplet and (C) chemical conversion in liquid membrane and further conversion inside droplet. Both (B) and (C) provide quasi-infinite sink conditions for extraction from the feed solution. 

Using Quasi-Elastic Light Scattering To Study Particle Size Distributions in Submicrometer Emulsion Systems... 

Quasi-elastic light scattering is an excellent technique for studying the formation and stability of submicrometer emulsions. Improvements in the methods of quasi-elastic light scattering data acquisition and analysis that enable full particle-size distribution studies of sub-micrometer emulsion systems are discussed. Using several oil/water emulsion systems as examples, we demonstrate the ability of these techniques to determine the effect of emulsifier concentration on the particle-size distribution produced by an inversion method of emulsification. Some of the benefits of obtaining the full distribution are also discussed. 

Assuming that the steady state of diffusion into the globule exits and the reaction of the front moves slowly in comparison to solute diffusion, a quasi-steady-state periphery of the emulsion globule is stated. The flux of the solute can be obtained by... 

---