Anion, increased concentration reducing action

Finally, some general rules for the amount of surfactant appear to be vaHd (13). For anionic surfactants the average size of droplets is reduced for an increase of surfactant concentration up to the critical micellization concentration, whereas for nonionic surfactants a reduction occurs also for concentrations in excess of this value. The latter case may reflect the solubiHty of the nonionic surfactant in both phases, causing a reduction of interfacial tension at higher concentrations, or may reflect the stabilizing action of the micelles per se. 

Action on the plasma membrane is the first and most fundamental of the bewildering array of deleterious effects of the cinnamic and benzoic acids. They reduce the transmembrane electrochemical potential with the immediacy and extent of that action depending on the concentration and lipid solubility of the compound.35,37,45,60 Rate of uptake also is concentration and pH-dependent, with transfer into and across the membrane greatest with lower pH conditions and higher external concentrations.60 Phenolic acid-induced depolarization of membranes causes a nonspecific efflux of both anions and cations accompanying the increased cell membrane permeability, and these membrane effects correlate with an inhibition of ion uptake. The phenolic acids suppress absorption of phosphate, potassium, nitrate, and magnesium ions, and overall changes in tissue... 

Stout and Meagher (1948) showed that addition of sulfate to the culture medium reduced uptake of radioactive Mo by tomatoes (Table 14.1). Stout et al. (1951) confirmed the action of S to decrease Mo uptake from solution culture and showed that the effect was more pronounced in shoots and leaves than in roots (Table 14.2). They also demonstrated that S decreased Mo uptake by tomatoes and peas in soil culture (Table 14.3). They attributed the effect of S in decreasing Mo uptake to direct competition for plant uptake between divalent anions of the same size. Bush et al. (1981) found that addition of 0.05 mEq of sulfate per liter of solution decreased Mo uptake by tall fescue, but that further increases in S concentration had little additional effect (Table 14.4). 

---