Double-layered membrane cross section

Figure 5 Cross-section of double-layered composite membrane the top layer. A, Is a dense poly(l,6-dlmethy 1-1,4-pheny lene oxide), the Intermediate layer, B, Is made of poly(dl-methyl siloxane) and the support, C, Is a porous 150 m polysulfone support. The membrane displays a separation factor of 4.1 toward an O /No air mixture and over 5 X 10"...

The simultaneous spinning of two polymer solutions to make a double-walled hollow fiber (active layer and support layer) is one of the recent developments. Figure 2.6 shows the schematic representation of the spinneret and the cross section of the membrane during spinning. 

The next barrier present in gram-negative bacteria is also a continuous, but a much more compact, layer of closely packed macromolecules. This entity, referred to as the outer membrane, consists predominantly of lipopolysaccharides (LPS), proteins, and phospholipids. The proteins have been estimated to contribute to about 50% of the surface area of this layer. The lipid-protein-polysaccharide components of the outer membrane form a matrix which appears in cross section as a typical double-tracked structure, similar to a phospholipid bilayer. This matrix is involved in a multiplicity of interactions of the cell surface with its exterior and interior environment. The outer membrane is known to function as a barrier to a large number of compounds, such as the antibiotics, actinomycin D, penicillin G, polymyxin, and bacitracin. In addition to preventing the entry of certain compounds, the outer membrane can also be viewed as a means of keeping enzymes of the periplasmic space trapped within the domain of the cell. 

FIGURE 15.26 (a) Schematic diagram of a dual-layer hollow-fiber spinning process (b) cross section of triple-orifice spinneret (Adapted from L. Setiawan et al.. Journal of Membrane Science, 423-424, 73-84, 2012.) and (c) fabrication process of a dual-layer flat-sheet membrane using a double-blade casting machine. (Adapted from S.A. Hashemifard et al. Journal of Membrane Science, 375, 258-267, 2011.)... 

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