Article history: Received 13 March 2012 Received in revised form 16 May 2012 Accepted 22 May 2012 Available online 25 June 2012

A model for self-propulsion of a colloidal particle--the osmotic motor--immersed in a dispersion of "bath" particles is presented. The nonequilibrium concentration of bath particles induced by a surface chemical reaction creates an osmotic pressure imbalance on the motor causing it to move. The ratio of the speed of reaction to that of diffusion governs the bath particle distribution which is e...

We present here a procedure for growing lipid tubules in vitro. This method allows us to grow tubules of consistent shape and structure, and thus can be a useful tool for nano-engineering applications. There are three stages during the tubule growth process: initiation, elongation and termination. Balancing the forces that act on the tubule head shows that the growth of tubules during the elong...

Articular cartilage is a hydrated soft tissue composed of negatively charged proteoglycans fixed within a collagen matrix. This charge gradient causes the tissue to imbibe water and swell, creating a net osmotic pressure that enhances the tissue's ability to bear load. In this study we designed and utilized an apparatus for directly measuring the osmotic pressure of chondroitin sulfate, the pri...

The electrosteric stabilization of model colloidal dispersions is quantified through high-frequency rheometry and complementary techniques. Model aqueous dispersions with a poly(butyl acrylate)polystyrene core and a layer of poly(methacrylic acid) grafted onto the surface are prepared and characterized. The influence of pH, electrolyte concentration, and amount of polymer in the stabilizing lay...

Analysis of the cell sap of Hydrodictyon patenaeforme Pocock, from California indicates the usual marked accumulation of potassium, which is 4000 times as concentrated as in the surrounding pond water. Small amounts of sodium and calcium were found. Chloride makes up about three-fourths of the anions, with a very high sulfate, and much lower bicarbonate concentration accounting for most of the ...

The analysis of Sha'afi et al. (Sha'afi, Rich, Mickulecky, Solomon 1970 J Gen Physiol 55: 427-450) for determining solute permeability in red blood cells has been modified and applied to turgid plant cells. Following the addition of permeating solute to the external medium, a biphasic response of cell turgor can be measured with the pressure probe in isolated internodes of Chara corallina. Afte...

A method of measuring the water potential of stored potato tubers (Solanum tuberosum L.) was needed to investigate the relationship of bacterial soft rot in tubers to water potential. Pressure chamber measurements, while useful for tubers with functional stolons, cannot be made on stored tubers. Measurements could be made on excised tissue pieces in a hygrometer chamber and with hygrometers imp...

In simulations and experiments, we study the drying of films containing mixtures of large and small colloidal particles in water. During drying, the mixture stratifies into a layer of the larger particles at the bottom with a layer of the smaller particles on top. We developed a model to show that a gradient in osmotic pressure, which develops dynamically during drying, is responsible for the s...