Surfactants are amphipathic compounds containing both hydrophilic and hydrophobic groups, capable to lower the surface or interfacial tension. Considering the advantages of the use of biosurfactants produced by microorganisms, the aim of this paper was to develop and characterize a biosurfactant produced by Streptomyces sp. DPUA1559 isolated from lichens of the Amazon region. The microorganism ...

Ferula gumosa  Boiss is one of the natural plants of Iran whose exudates (Barijeh) can be used in food industry. In the present study the properties of the gum extracted from tubers of Ferula gumosa were examined. For this purpose, gum was extracted from crude exudates by alcoholic extraction with 90% (v/v) ethanol. The purity of gum was relatively high, and it was composed mostly ...

background: a glycolipopeptide biosurfactant produced by pseudomonas aeruginosa strain ikw1 reduced the surface tension of fermentation broth from 71.31 to 24.62 dynes/cm at a critical micelle concentration of 20.80 mg/l. the compound proved suitable for applications in emulsion stabilization in food, as well as in cosmetic and pharmaceutical formulations. methods: in the present study, placket...

New quaternized oligomeric surfactants containing 4 or 8 alkyl chains were synthesized using ethylenediamine or poly(amidoamine) dendrimers as the central scaffold. Electrical conductivity, surface tension, and pyrene fluorescence measurements, as well as dynamic light scattering were used to characterize their properties. In addition, the dependence of these properties on the alkyl chain lengt...

In the present paper, we aim to investigate the dependence of surface tension on the surface properties and reveal the counter-ion effects on the adsorption of ionic surfactants on the solution surface. The surface tension, surface excess and surface concentration (defined as the amount of surfactant adsorbed in the surface phase divided by the surface area) of two anionic surfactants, namely d...

......................................................................................................................................... x Chapter 1: Introduction to Capillary Driven Microfluidics ..................................................... 1 1.1 Surface Tension-Confined Microfluidics ........................................................................ 1 1.2 Capillary-Driven Micr...

dam spillways are the structures that lead rightly and safely the outflow downstream, so that the dam integrity can be guaranteed. many accidents with dams have been caused by an inadequate spillway design or insufficient capacity. to accurately respond the hydraulic spillways, designers use physical modeling for designing this kind of structures. the scale effect in the spillway modeling, as a...

The method of matched asymptotic expansions is used to solve for the free surface of a thin liquid drop draining down a vertical wall under gravity. The analysis is based on the smallness of the surface tension term in the lubrication equation. In a region local to the front of the drop, where the surface curvature is large, surface tension forces are significant. Everywhere else, the surface c...

We perform energy estimates for a sharp-interface model of two-dimensional, twophase Darcy flow with surface tension. A proof of well-posedness of the initial value problem follows from these estimates. In general, the time of existence of these solutions will go to zero as the surface tension parameter vanishes. We then make two additional estimates, in the case that a stability condition is s...