Consideration on the Formulation of Benzoyl Peroxide at Ambient Temperature: Choice of Non-Polar Solvent and Preparation of Submicron Emulsion Gels

ABSTRACT

The aim of this study performed at ambient temperature was first to determine the solubility of benzoyl peroxide in various solvents with a large range of polarity. All these solvents can be used in the dermatological field. Then, using the most suitable solvent, a new drug vehicle submicron oil-in-water emulsion was formulated. Correlation between dielectric constant (ε) and drug solubility in various solvents and different binary mixtures was verified. An original ternary diagram with surfactant–co-surfactant/oil/water was performed at low temperature to determine the regions of submicron emulsions. A dramatic change in the magnitude of benzoyl peroxide solubility occurred above a dielectric constant value of about 20. The solubility of this drug can be enhanced by the replacement of polar solvent by a vehicle of lower dielectric constant. A stable submicron emulsion gel was made with cremophor EL, glycerol, caprilic–capric triglycerides, and water in the proportion of 20–20/35/25, respectively; 1.5% benzoyl peroxide was also added. This submicron emulsion vehicle consisted of oil droplets, with a mean diameter of approximately 100–150 nm, dispersed in a continuous water phase. These studies confirm the potential of benzoyl peroxide incorporation into submicron emulsion gel and the stability of this formulation.     

Optimizing replay intensity and resolution in aberration-compensated off-axis holograms by ambient humidity control

Abstract

In hologrammetry it is desirable to reconstruct the real image rather than the virtual image as the latter must be viewed at a distance through the window of the holographic plate itself. When a scene is located in water but the image is replayed into air, it is necessary to correct for the refractive index difference by reconstructing the image with shorter wavelength illumination and changing the beam angle to satisfy the grating equation. However, this means that the Bragg condition may no longer be satisfied during replay, reducing the diffraction efficiency and decreasing the signal-to-noise ratio of the reconstructed images. Changing the replay beam angle to satisfy better the Bragg condition makes the images brighter but also renders them unusable by increasing the optical aberrations. Our solution is to alter the Bragg properties of the hologram by altering the humidity of the surrounding atmosphere. This approach has been experimentally demonstrated for Agfa 8E56HD emulsions by measuring the brightness and resolution of a reconstructed real image from an off-axis hologram over a humidity range from 6 to 93 per cent. The emulsion swelling and its effect on the Bragg properties of the hologram were modelled using the Flory-Huggins theory of polymer swelling.     

瓜尔豆胶对大豆分离蛋白乳浊液稳定性的影响

研究了不同pH值条件下瓜尔豆胶对大豆分离蛋白乳浊液乳析稳定性和絮凝稳定性的影响。研究结果表明 ,在瓜尔豆胶浓度低于 0 0 4%时 ,随着瓜尔豆胶浓度的增加 ,乳浊液的稳定性逐渐增加。当多糖浓度高于 0 0 4%时 ,液滴发生排斥絮凝 ,体系的稳定性急剧下降 ,更高浓度的瓜尔豆胶因与乳浊液液滴间的热力学不相容性而导致体系发生各向同性和各向异性相分离。     

The characterization of the semi-solid W/O/W emulsions with low concentrations of the primary polymeric emulsifier

Semi-solid multiple W/O/W emulsions with low concentrations (0.8, 1.6 and 2.4% w/w) of lipophilic polymeric primary emulsifier PEG-30-dipolyhydroxystearate (PDHS) have been formulated. Both emulsions, primary and multiple, were prepared with high content of inner phase (Phi1 = Phi2 = 0.8). All the formulations differ only in the lipophilic emulsifier concentration. Evaluating several parameters such as macroscopic and microscopic aspect, droplet size, accelerated stability under centrifugation and flow and oscillatory rheological behaviour, assessed the multiple systems. It is possible to formulate the semi-solid W/O/W multiple emulsions with low concentrations of PDHS as the primary emulsifier. It appeared that the highest long-term stable multiple emulsion with the lowest droplet size, the highest apparent viscosity and highest elastic characteristic, was the sample with the highest concentration (2.4% w/w) of the primary emulsifier.     

Time-dependent competitive adsorption of milk proteins and surfactants in oil-in-water emulsions

Competitive adsorption of pure milk proteins and non-ionic surfactants has been studied in model oil-in-water emulsions (4 g kg^?1 β-lactoglobulin or β-casein, 200 g kg^?1 n-hexadecane) as a function of the age of the adsorbed protein layer at the oil-water interface. With β-lactoglobulin-stabilised emulsions containing oil-soluble surfactant C₁₂ E₂ (diethylene glycol n-dodecyl ether), there is found to be a steadily increasing amount of protein associated with the emulsion droplets over a few hours following emulsification. Addition of water-soluble surfactant Tween 20 (polyoxyethylene (20) sorbitan monolaurate) to a β-lactoglobulin-stabilised emulsion (with or without C₁₂E₂) leads to less protein displacement if the emulsion is aged prior to addition of Tween 20. Moderate additions of C₁₂E₂ or Tween 20 produce no time dependence in the competitive adsorption in β-casein-stabilised emulsions, although some time dependence is observed when C₁₂E₂ and a high concentration of Tween 20 are present together. Crystallisation of the oil phase in β-casein-stabilised emulsions at pH 7 leads to a lowering of the measured protein surface concentration, especially in the presence of C₁₂E₂ and a reduction in the surfactant to protein molar ratio required for complete protein displacement by water-soluble surfactant (Tween 20 or octaethylene glycol n-dodecyl ether). Under more acidic conditions of pH 5 or pH 3, the surface coverage and ease of displacement of β-lactoglobulin at the surface of liquid emulsion droplets is substantially different from that under neutral pH conditions.     

Starch and Egg White lnfluence on Properties of Bologna Sausage as Related to Fat Content

Surface Response Methodology (RSM) was used for simultaneous analysis of levels of added starch (S) and egg white (EW) and their effects on binding and textural characteristics of meat emulsions as related to their fat content (F). Regression models were significant (P < 0.01) for binding properties (cooking loss and purge loss), hardness, chewiness and penetration force and not significant (P > 0.05) for pH, cohesiveness, springiness and work of penetration. Of the three variables studied, starch most influenced binding and textural properties. Starch reduced cooking loss and purge loss and increased hardness, chewiness and penetration force. Egg white affected texture (increased hardness, chewiness and penetration force) and did not affect binding properties. Each individual variable was generally not influenced by the other two.     

A very stable W/O/W multiple emulsion

Synopsis
The comparison of the results of microscopic, conductimetric and rheologic analyses carried out on the same triple W/O/W emulsion, immediately following its manufacture and 10 years later, indicates the remarkable stability of such system. This stability illustrates the great potential of this formula in the protection of unstable ingredients, with regard to external stress, when encapsulated with a high yield.
Résumé
La comparison des résultats des analyses microscopiques effectuées sur une même fomule d'émulsion multiple H/L/H, juste après sa fabrication et après 10 ans de conservation, ont permis de mettre en évidence la remarquable stabilité de ce système. Cette stabilité démontre les grandes possibilités de cette formule dans la protection, vis à vis des milieux extérieurs, des substances fragiles incorporés avec un haut rendement d'encapsulation.     

Preparation of acrylate-based copolymer emulsion and its humidity controlling mechanism in interior wall coatings

In order to investigate the humidity controlling mechanism of an acrylate-based copolymer emulsion (ACE), the storage stable copolymer of a novel waterborne two-pack system was prepared by emulsion polymerization using main monomers and functional monomers, such as acrylic acid (AA) and diacetone acrylamide (DAAM). Influencing factors such as those affecting the coagulum and particle size of the emulsion were investigated. The obtained ACE was characterized by FT-IR spectra and dynamic light scattering (DLS) analysis, and was applied to the preparation of wall coatings with humidity controlling functions, and showed a large capacity for water absorption (274%), increasing indoor humidity and dehumidification in dry or moist environments. Based on analysis of the micro-structure of the coatings and their humidity controlling properties, a humidity controlling mechanism was suggested. The coating properties of the ACE and its film were measured, and showed excellent hardness, gloss and water resistance properties. ACE coatings (ACE-C) exhibited humidity control and excellent moisture retention due to the porous structure of the filler combined with the acrylate-based copolymer.     

SODIUM LIGNIN SULFONATE TO STABILIZE HEAVY CRUDE OIL-IN-WATER EMULSIONS FOR PIPELINE TRANSPORTATION

ABSTRACT

The efficiency of sodium lignin sulfonate (SLS) as an anionic surfactant derived from waste wood pulping industry in stabilizing an Egyptian heavy crude oil (Geisum)-in-water emulsions for pipeline transportation has been investigated. The stability and rheology of the emulsions stabilized by SLS or with a nonionic surfactant nonyl phenol diethylenetriamine formaldehyde ethoxylate (NDFE) individually or in a mixture have been studied. It has been found that the dynamic shear viscosity of the crude oil decreases substantially when it is emulsified with water in the form of an oil-in-water type of emulsion. The stability of the oil-in-water emulsion increases as the surfactant concentration increases. Potable water and saline water containing different molar concentrations of NaCI have been used to study the effect of aqueous phase salinity on the stability and viscosity of the emulsion. Surfactant dissolved in saline water has been utilized to find out the possibility of injecting the surfactant into a well bore to effect emulsification in the pump or tubing for enhancing the production of heavy crude oils as oil-in-water emulsion. The study revealed that, the viscosity of the emulsion containing potable water is always less than that containing saline water and the viscosity increases as the salt content increased.