Water dual membranes

M. P. Del Pino and B. Durham, Wastewater reuse through dual-membrane processes opportunities for sustainable water resources. Desalination 124, 271-277 (1999). 

Lozier J., Jones G. (1997), Meeting the challenges of the new drinking water regulations with dual-membrane treatment, Proc. AWVC A Membrane Technolog) Conference, New Orleans, Feb. 97. 

Mechanical filtration is first performed in dual media components featuring a first layer of anthracite to capture the final oil traces, followed by a bed of quartz sand of proper granulometry to prevent silica entrainment by water. Dual media filters can retain particles larger than few microns and are followed by cartridge filters. They represent the last filtration stage before the membrane and are suited to remove fine particles having size larger than about 1 pm. 

A dual isotope labeling technique [85] has been used to measure membrane permeability in plant cells, based on the selective permeabiHty of the membranes of living cells to tritiated water and carbon-14 labeled mannitol. Kieran [29] showed that the results of the dual isotope labeling and Evan s Blue staining methods correlated well as indicators of cell viability however, the latter was preferable in terms of reagent cost and ease of analysis. 

FIGURE 19-55 Dual roles of cytochrome b6f and cytochrome c6 in cyanobacteria. Cyanobacteria use cytochrome bsf, cytochrome c6, and plastoquinone for both oxidative phosphorylation and photophosphorylation. (a) In photophosphorylation, electrons flow (top to bottom) from water to NADP+. (b) In oxidative phosphorylation, electrons flow from NADH to 02. Both processes are accompanied by proton movement across the membrane, accomplished by a Q cycle. 

A second commercially available electrolyzer technology is the solid polymer electrolyte membrane (PEM). PEM electrolysis (PEME) is also referred to as solid polymer electrolyte (SPE) or polymer electrolyte membrane (also, PEM), but all represent a system that incorporates a solid proton-conducting membrane which is not electrically conductive. The membrane serves a dual purpose, as the gas separation device and ion (proton) conductor. High-purity deionized (DI) water is required in PEM-based electrolysis, and PEM electrolyzer manufacturer regularly recommend a minimum of 1 MQ-cm resistive water to extend stack life. 

As a class of tissue, epithelia demarcate body entry points, predisposing a general barrier function with respect to solute entry and translocation. The intestine is lined with enterocytes, which are polarized cells with their apical membrane facing the intestinal lumen that is separated by tight junctions from the basolateral membrane that faces the subepithelial tissues. In addition to their barrier function, the epithelia that line the GI tract serve specialized functions that promote efficient nutrient digestion and absorption and support other organs of the body in water, electrolyte, and bile salt homeostasis. The homeostatic demand on GI tissue that results from this dual function may pose special transport consideration compared with solute translocation across biologically inert barriers. 

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