Electro-osmotic flow, the driving of fluid at nano- or micro-scales with electric field, has found numerous applications, ranging from pumping to chemical and biomedical analyses in micro-devices. Electro-osmotic flow exhibits a puzzling hysteretic behavior when two fluids with different concentrations displace one another. The flow rate is faster when a higher concentration solution displaces ...

Freshly isolated frog rod outer segments are sensitive osmometers which retain their photosensitivity; their osmotic behavior reveals essentially the same light-sensitive Na(+) influx observed electrophysiologically in the intact receptor cell. Using appropriate osmotic conditions we have examined freeze-etch replicas of freshly isolated outer segments to identify the membrane which regulates t...

A novel elementary osmotic pump tablet was developed. The system uses the core of drug-resin complexes (DRCs) loaded with propranolol hydrochloride (PNH) for time-controlled delivery. In traditional osmotic pump tablets (OPTs), the lag time was always minimized. However, in the DRCs osmotic pump tablet (DRCOPT), the lag time was increased to achieve the time-controlled delivery. The quantity of...

The intervertebral disk has an excellent swelling capacity to absorb water, which is thought to be largely due to the high proteoglycan composition. Injury, aging, degeneration, and diurnal loading are all noted by a significant decrease in water content and tissue hydration. The objective of this study was to evaluate the effect of hydration, through osmotic loading, on tissue swelling and com...

The permeability properties of frog rod photoreceptor outer segment discs were investigated in preparations of purified, dark-adapted, outer segment fragments by the techniques of direct volume measurement and electron microscopy. Outer segment discs were found to swell and contract reversibly in response to changes in the osmotic pressure of the bathing medium in accordance with the Boyle-van'...

In this paper, we demonstrate, for the first time, how an external osmotic gradient can be used to regulate diffusion of solutes across a lipid membrane. We present experimental and theoretical studies of the transport of different solutes across a monoolein membrane in the presence of an external osmotic gradient. The osmotic gradient introduces phase transformations in the membrane, and it ca...

Tissue behavior is governed to a large extent by composition and microstructure of the extracellular matrix. In cartilage, various biopolymers (glycosaminoglycans, collagen, hyaluronic acid, etc.) are integrated into a complex network that imparts the tissue with its low-friction characteristics and load-bearing capacity. The structure of collagen (predominantly type II collagen) gives it tensi...

We study the buckling of elastic spherical shells under osmotic pressure with the osmolyte concentration of the exterior solution as a control parameter. We compare our results for the bifurcation behavior with results for buckling under mechanical pressure control, that is, with an empty capsule interior. We find striking differences for the buckling states between osmotic and mechanical buckl...