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...

We have developed a statistical theory for columnar aggregates of semi-flexible polyelectrolytes. The applicability of previous, simplified theories was limited to polyelectrolytes with unrealistically high effective charge and, hence, with strongly suppressed thermal undulations. To avoid this problem, we utilized more consistent approximations for short-range image-charge forces and steric co...

A theory is proposed which allows us to calculate the distribution of the multivalent counterions around a colloidal particle using the cell model. The results are compared with the Monte Carlo simulations and are found to be very accurate in the two asymptotic regimes, close to the colloidal particle and far from it. The theory allows to accurately calculate the osmotic pressure and the effect...

Cells swell in response a hypoosmotic challenge. By converting osmotic pressure to hydrostatic pressure at the cell membrane via van't Hoff's law, and converting that to tension via Laplace's law one predicts that the cell membrane should stretch and become stiff. We tested this prediction using the atomic force microscopy. During osmotic swelling cells did not become stiff and generally became...

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...

1. The swelling and the osmotic pressure of gelatin at pH 4.7 have been measured in the presence of a number of salts. 2. The effect of the salts on the swelling is closely paralleled by the effect on the osmotic pressure, and the bulk modulus of the gelatin particles calculated from these figures is constant up to an increase in volume of about 800 per cent. As soon as any of the salts increas...

This study was performed to evaluate the effectiveness of three different conditions of osmotic pressure (325, 365 and 385 mOsm kg-1) in combination with dimethyl sulfoxide (DMSO) and NaCl or glucose on spermatozoa DNA damage, rate and duration of motility. Sperm was collected from eight healthy mature Mesopotamian catfish, evaluated microscopically and pooled at 25 °C. The pooled sperm samples...

Several recent works have considered the pressure exerted on a wall by a model polymer. We extend this consideration to vesicles attached to a wall, and hence include osmotic pressure. We do this by considering a two-dimensional directed model, namely that of area-weighted Dyck paths. Not surprisingly, the pressure exerted by the vesicle on the wall depends on the osmotic pressure inside, espec...

Peanut (Arachis hypogaea L.) and cotton (Gossypium hirsutum) plants were grown for 4 weeks in saline, isoosmotic rooting substrates with different proportions of K and Na. Isoosmotic media did not affect growth (except at the highest external K concentrations) or estimates of intracellular osmotic pressure in expanding leaves (i.e. osmotic pressure of leaf sap and intracellular osmotic pressure...