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The dynamic surface properties of mixed monolayers of 1,2-Dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC) and negatively charged polystyrene particles (PS) of different size were investigated with the aim to model the interactions of particles with biointerfaces. Special attention was paid to the aggregation of the particles at the water/air interface. The particle aggregates have a weaker influence...
We report on the synthesis of copper-silver core-shell (Cu@Ag) particles with about 1μm-diameter Cu core coated with a thin (∼20nm) silver shell, for application in printed electronics as low cost conductive ink. The process is based on using the environmentally friendly sodium formaldehyde sulfoxylate dehydrate as a reducing agent for copper ions and two types of polymeric stabilizers (nonionic PVP...
To predict the stability of protein-stabilized emulsions against flocculation under different conditions (pH and concentration), a quantitative description of the effect of the relevant factors is essential. Typically, pH is considered to affect the protein charge (viz. zeta potential) and thereby the interactions between the emulsion droplets. In this study, it is shown that emulsion flocculation...
Marangoni flows offer an interesting and useful means to transport particles at fluid interfaces with potential applications such as dry powder pulmonary drug delivery. In this article, we investigate the transport of partially wetted particles at a liquid/vapor interface under the influence of Marangoni flows driven by gradients in the surface excess concentration of surfactants. We deposit a microliter...
Therapeutic pulmonary surfactants are currently investigated in clinical medicine as corticosteroids delivery vehicles into the lung. The influence of the corticosteroids Budesonide and Beclometasone dipropionate on the surface properties of aqueous solutions of the therapeutic surfactant preparation Curosurf® has been studied using the black foam film and the wetting film methods. The measurements...
Sessile liquid droplets deposited on soft substrates may cause substrate deformation. The substrate elasticity affects the apparent contact angle and the spreading dynamics of the sessile drop. In the present work, a model for description of a droplet on an elastic substrate is developed using the disjoining pressure concept. A Finite Element Method for the elasticity problem in a substrate is coupled...
Equilibrium of liquid droplets on soft deformable substrates is investigated. Disjoining pressure action in the vicinity of the apparent three phase contact line is taken into account. It is shown that the combined disjoining and capillary pressure action determine the substrate deformation. A simplified linear disjoining pressure isotherm and simple Winkler's model to account for the substrate deformation...
Onset of surface-tension driven convection in a heated liquid layer with insoluble surfactant adsorbed on the free surface is analyzed in the framework of the linear stability theory. The limit of a deep layer is considered. The general dispersion relation is obtained and investigated analytically and numerically.
Experimental and numerical study of the droplet formation mechanism in thin layers of water-isopropanol mixtures under the laser heating is presented. It is shown that after the beginning of the irradiation the thermocapillary convection dominates that result in the thinning of the layer in the heated area due to the flow of liquid into the cold area. In a few seconds, the loss of isopropanol in the...
Spontaneous formation of aqueous droplets in kerosene was observed, which was facilitated by the presence of an oil soluble surfactant: Span® 80 at concentrations above CMC. Kerosene/water interfacial tension under all conditions studied was not lower than 4mN/m. Therefore, ultra-low interfacial tension was not required for this process to occur spontaneously. The process was caused by a transfer...
The dynamic surface pressure Π and the two components E’ (real part) and E” (imaginary part) of the dynamic surface dilational modulus of adsorbed β-lactoglobulin (BLG) layers at the water/air interface were measured by oscillating drop/bubble profile analysis tensiometry with the aim to enlarge information on the surface rheology of solutions of this practically important protein. The effects of...
The effect of chirality on the thermodynamic behavior, the morphological features, and the 2D lattice structures of 3-monopalmitoyl-sn-glycerol monolayers is studied. The results are based on measurements of the surface pressure-area (π-A) isotherms, Brewster angle microscopy (BAM), and Synchrotron X-ray diffraction at grazing incidence (GIXD). The π-A isotherms of the enantiomeric 3-monopalmitoyl-sn-glycerol...
Despite the significant effort spent over the years to study wetting and dewetting phenomena of droplets on solid substrates under applied forces, there are still many unresolved issues. To name a few, a concise theory for the two dimensional contact line is missing. Also, a controversy has recently arisen for the effect of droplet size on the tangential force required for the inception of sliding...
The adsorption of proteins (β-lactoglobulin, β-casein) and the oxyethylated non-ionic surfactants C10EO8 and C14EO8 at the aqueous solution/air interface is strongly enhanced and accelerated by the presence of hexane vapour in the air phase caused by the co-adsorption of hexane molecules. Due to this hexane co-adsorption, the dependence of dilational visco-elasticity modulus on surface pressure is...
The process of drop detachment from a capillary tip and formation of satellite droplets is studied for solutions of trisiloxane surfactants above the critical aggregation concentration. Two of the studied surfactants self-assemble in bilayer based phases, whereas the third forms micelles. The difference in the aggregates formed results in an essential difference in the rate of equilibration between...
It has been recently shown that thermal treatment of polydimethylsiloxane (PDMS) films in air atmosphere leads to modification of wetting characteristics of the film surface. In the present work we studied the wettability and imbibition properties of substrates produced by thermal treatment of PDMS films of different thicknesses and elastic properties at 650°C in atmosphere of air. The samples undergo...
Current drug delivery devices (DDD) are mainly based on the use of diffusion as the main transport process. Diffusion-driven processes can only achieve low release rate because diffusion is a slow process. This represents a serious obstacle in the realization of recent successes in the suppression of lymphatic metastasis and in the prevention of limb and organ transplant rejection. Surprisingly, it...
This paper presents a novel approach to the characterization of hybrid cation-exchange membranes by applying the “fine porous membrane” model. We verify this approach using samples of cation-exchange membranes synthesized on the base of the perfluorinated MF-4SC membrane and halloysite nanotubes and prepared by the casting method. For characterization we use the initial pure MF-4SC membrane and two...
Solid supported lipid layer has been of broad interest for decades. DPPC modified Ti-6Al-4V could be used as dental and orthopedic implants because of excellent mechanical property, corrosive resistance and enhanced biocompatibility. However, to be long time lasting, biostability is also a crucial property of implanted surface. In previous Part I and Part II surface properties of Ti-6Al-4V depending...
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