Aerobic operation of an immersed hollow fibre membrane bioreactor, treating municipal wastewater supplemented with molasses solution, has been studied across mixed liquor suspended solids (MLSS) concentrations between 8 and 32 g L(-1), the higher concentrations being normally associated with thickening operations. Only a marginal loss in membrane permeability was noted between 8 and 18 g L(-1) ...

A numerical model was used to investigate the effect of spatial variability in fracture permeability on liquid seepage and moisture distribution in the vicinity of a waste emplacement drift in the unsaturated zone (UZ) of Yucca Mountain. The model is based on a two-dimensional, cross-sectional, dual-permeability model of the unsaturated zone at Yucca Mountain and uses a stochastic approach to i...

The rate of unidirectional [14C]urea efflux from human red cells was determined in the self-exchange and net efflux modes with the continuous flow tube method. Self-exchange flux was saturable and followed simple Michaelis-Menten kinetics. At 38 degrees C the maximal self-exchange flux was 1.3 X 10(-7) mol cm-2 s-1, and the urea concentration for half-maximal flux, K1/2, was 396 mM. At 25 degre...

Recent studies of the fluxes of sodium and chloride across euryhaline teleost fish have shown that acclimation to fresh water involves a sharp reduction in the flux of both ions (Evans, 1967 c, 1969; Motais, 1967; Maetz et al. 1967 a, b; Potts & Evans, 1967; Ports et al. 1967). It has been shown, at least in Fundulus heteroclitus (Potts & Evans, 1967), Tilapia mossambica (Potts et al. 1967), Xi...

integrally skinned asymmetric membranes based on nanocompositepolyethersulfone were prepared by the phase separation process using the supercritical co2 as a nonsolvent for the polymer solution. in present study, the effects of temperature and nanoparticle on selectivity performance and permeability of gases has beeninvestigated. it is shown that the presence of silica nanoparticles not only di...

Corneal transparency and hydration control are dependent on HCO(3)(-) transport properties of the corneal endothelium. Recent work (13) suggested the presence of an apical 1Na(+)-3HCO(3)(-) cotransporter (NBC1) in addition to a basolateral 1Na(+)-2HCO(3)(-) cotransporter. We examined whether the NBC1 cotransporter contributes significantly to basolateral or apical HCO(3)(-) permeability and whe...

Clostridium botulinum produces a large toxin complex (L-TC) that increases paracellular permeability in intestinal epithelial cells by a mechanism that remains unclear. Here, we show that mitogen-activated protein kinases (MAPKs) are involved in this permeability increase. Paracellular permeability was measured by FITC-dextran flux through a monolayer of rat intestinal epithelial IEC-6 cells, a...

Hayden, Ursula L., and Hannah V. Carey. Neural control of intestinal ion transport and paracellular permeability is altered by nutritional status. Am J Physiol Regulatory Integrative Comp Physiol 278: R1589–R1594, 2000.—This study examined the effect of fasting on the neural control of ion transport and paracellular permeability in piglet jejunum. Muscle-stripped tissues from fed or 48-h fasted...

Liposome permeability to net proton-hydroxide flux was compared under two conditions that have produced extreme values in previous studies. In the first [Nichols, J.W. & Deamer, D.W. (1980) Proc. Natl. Acad. Sci. USA 77, 2038-2042] small pH gradients were permitted to decay near pH 7 and permeability coefficients in the range of 10(-4) cm/sec were obtained. In the second [Nozaki, Y. & Tanford, ...