The mechanism of melibiose symport by the melibiose permease of Escherichia coli was investigated by further analyzing the Na+ (H+ or Li+)-coupled facilitated diffusion reactions catalyzed by the carrier in de-energized membrane vesicles, with particular emphasis on the reaction of sugar exchange at equilibrium. It is first shown that melibiose exchange at equilibrium proceeds without concomita...

Potassium ion and Na(+) influx and efflux rates into and from excised barley roots are compared with the maximum capacity of accumulation. Potassium ion and Na(+) influx and efflux involve a cation exchange that is independent of simultaneous exchange of the accompanying anion. These exchange fluxes depend on the concentration and cation composition of the solutions from which they originate. S...

soil productivity is generally associated with poor nutrient status and the physical condition of the soil, but the effect of soil mineralogy on soil productivity has received little attention. in this qualitative study, interactions between mineralogy and physico-chemistry and their role on the productivity of two luvisols, an arenosol and a vertisol are investigated. minerals identified in th...

A proton exchange (Nafion-117), a cation exchange (Ultrex CMI7000), an anion exchange (Fumasep FAD), and a bipolar (FumasepFBM) membrane have been studied to evaluate the principle suitability of ion exchange membranes as separators between the anode and the cathode compartment of biological fuel cells. The applicability of these membranes is severely affected by the neutral pH, and the usually...

Herein, graphene oxide nanosheets (GO) were synthesized and employed as an additive at various proportions to fabricate a novel cation exchange membrane based on grafted cellulose acetate with sodium 4-styrenesulfonate (GCA) via solution casting method for direct methanol fuel cell (DMFC) applications. The structure of composite membranes has been examined using FTIR, TGA, SEM, DSC. physicochem...

Exchange of intracellular sodium for extracellular lithium readily occurs in vascular smooth muscle, but the mechanism of this exchange is not known. These studies examined whether a sodium-lithium countertransport system was present in the cell membrane of vascular smooth muscle. A sarcolemmal-enriched vesicle preparation was obtained from canine superior mesenteric artery via a magnesium aggr...