33 research outputs found
Phase transition pathways for the production of 100 nm oil-in-water emulsions
Oil/water emulsions can be produced through phase inversion, by adding water to a reverse water/oil microemulsion. According to small angle neutron scattering experiments and visual observations performed during phase inversion, the stages of this process are as follows: (i) upon water addition, the microemulsion gives way to a highly swollen lamellar phase; (ii) the transient lamellar phase breaks up to yield an array of droplets; (iii) the droplets loses the correlations of the lamellar phase. This emulsion is already present less than one minute after the initial addition of water, and it reaches the final size distribution in one hour. The final population of oil droplets is homogenous with a mean diameter below 100 nm
Small-Angle Neutron Scattering Study of Crude Oil Emulsions: Structure of the OilâWater Interfaces
In Vitro Characterization and Mosquito (Aedes aegypti) Repellent Activity of Essential-Oils-Loaded Nanoemulsions
The nanoemulsions composed of citronella oil, hairy basil oil, and vetiver oil with mean droplet sizes ranging from 150 to 220Â nm were prepared and investigated both in vitro and in vivo. Larger emulsion droplets (195â220Â nm) shifted toward a smaller size (150â160Â nm) after high-pressure homogenization and resulted in higher release rate. We proposed that thin films obtained from the nanoemulsions with smaller droplet size would have higher integrity, thus increasing the vaporization of essential oils and subsequently prolonging the mosquito repellant activity. The release rates were fitted with Avramiâs equations and n values were in the same range of 0.6 to 1.0, implying that the release of encapsulated limonene was controlled by the diffusion mechanism from the emulsion droplet. By using high-pressure homogenization together with optimum concentrations of 5% (w/w) hairy basil oil, 5% (w/w) vetiver oil (5%), and 10% (w/w) citronella oil could improve physical stability and prolong mosquito protection time to 4.7Â h due to the combination of these three essential oils as well as small droplet size of nanoemulsion