Analytical and numerical studies of secondary electro-osmotic flow (EOF) and its mixing in microchannels with heterogeneous zeta potentials are carried out in the present work. The secondary EOFs are analyzed by solving the Stokes equation with heterogeneous slip velocity boundary conditions. The analytical results obtained are compared with the direct numerical simulation of the Navier-Stokes ...

I T HAD BEEN ESTABLISHED by previous observations”2 that heating normal human red blood cells increases their osmotic and mechanical fragiities, and results in their sequestration in the spleen37 and liver.8 Human erythrocytes undergo budding, and the heated red cells subdivide into fragments having a decreased ratio of surface volume and increased osmotic fragility.’ Kimber and Lander8 have sh...

We revisit the classical problem of diffusion-limited ion transport to a membrane (or electrode) by considering the effects of charged sidewalls. Using simple mathematical models and numerical simulations, we identify three basic mechanisms for overlimiting current in a microchannel: (i) surface conduction carried by excess counterions, which dominates for very thin channels, (ii) convection by...

A new hypothesis is presented for the mechanism of metabolic response during osmoregulation in the alga Dunaliella salina. We propose that the osmotic response is initiated by differential volume changes of the cytoplasm and the chloroplast (observed using the electron microscope) which alter the cytoplasmic orthophosphate concentration. This triggers a flow through the Pi/triose-phosphate shut...

Hepatic encephalopathy and brain edema are important complications in the course of a patient with acute liver failure. Presumed unrelated for many years, increasing evidence suggests that an increase in brain water is seen in all forms of hepatic encephalopathy. Ammonia, traditionally linked to the pathogenesis of hepatic encephalopathy, plays an important role in the increase in brain water. ...

The effective osmotic pressure across the blood-joint barrier is a key factor controlling synovial fluid volume and joint effusions. The effect of plasma colloid osmotic pressure (COP) on trans-synovial flow was studied directly in rabbit knees expanded by intra-articular fluid infusion. The synovial microcirculation was perfused with blood of varying COP. Absorption of fluid from the joint cav...

Water permeability coefficients of dog, cat, and beef red cell membranes have been measured under an osmotic pressure gradient. The measurements employed a rapid reaction stop flow apparatus with which cell shrinking was measured under a relative osmotic pressure gradient of 1.25 to 1.64 times the isosmolar concentration. For the dog red cell the osmotic permeability coefficient is 0.36 cm(4)/(...

Water transport across plasma membranes is a universal property of cells, but the route of such transport is unclear. In this study, volume changes of cells of the J774 murine macrophage-like cell line were monitored by recording the intensity of light scattered by the cells. We investigated the effects of several inhibitors of glucose transport on cell membrane osmotic water permeability as ca...

Monodisperse microcapsules with ultra-thin membranes are microfluidically designed to be highly sensitive to osmotic pressure, thereby providing a tool for the direct measurement of the osmotic strength. To make such osmocapsules, water-in-oil-in-water double-emulsion drops with ultra-thin shells are prepared as templates through emulsification of core-sheath biphasic flow in a capillary microf...