Double-layered membrane

Ultrastructural examination of nuclei in situ showed they were not surrounded by a continuous double-layered membrane, but that the membrane was interrupted by pores (Callan and Tomlin, 1950). These were not holes but were highly organized structures involved in transport between the nucleus and the cytosol. 

An interesting feature of the structure of Nitrobacter is the presence of several double-layered membranes... 

Cell Membrane 10-20 nm Doubled-layered membrane main semi-permeable barrier of cell 5-10% of cell dry wt 50% protein, 30% lipid and 20% carbohydrate... 

Cell membrane 0.007-0.01 Much-folded, double-layered membrane semipermeabie to nutrients... 

The free floating film is transferred to a microporous support by bringing a sheet of the support into contact with the underside of the ultrathin film, lifting it from the water surface.9 Also, two layers can be simultaneously cast and laminated to a carrier web.7 8 Numerous patents have appeared in recent years on the fabrication of gas separation membranes by float-casting, even including the double layer membrane technique.10 11... 

Endospores contain a newly replicated bacterial chromosome and a small portion of cytoplasm inside a double-layered membrane, all enclosed within a thick spore coat of protein (Fignre 6.15.3). This coat makes the endospore resistant to many harsh chemicals (Tortora et al., 2001). Most of the water present in the endospore is eliminated, and endospores do not carry out metabolic reactions. 

A spectacular example of a ridge and valley textile structure, 320 m in length, covers the central concourse of Denver Airport Terminal (1994) and is intended to mirror the snow-capped Rocky Mountains in the distance (Brown, 1994). This is a double-layer membrane used to improve the thermal and acoustic performance of the space (Berger, 2000, pp. 220-221). It is particularly employed to reduce the impact of aircraft engine noise on the interior. As Fig. 7.12 shows, here the distinct contrast between the bright membrane (bright, even though it is double-layer) and the duller surfaces at concourse level can clearly be seen, as discussed previously in Section 7.6.2. 

Shim IK, Suh WH, Lee SY, Lee SH, Heo SJ, Lee MC, et al. Chitosan nano-/microfibrous double-layered membrane with rolled-up three-dimensional structures for chondrocyte cultivation. J Biomed Mater Res A 2009 90A 595-602. 

In vitro, cardiac myocytes of foetal mice resupplied with oxygen and glucose after 1 h of deprivation showed degenerating mitochondria, myofibrils, and glycogen granules surrounded by a single or double layered membrane which at times was incomplete (Sybers etal. 1979). The vacuoles were most commonly located in the perinuclear region and the nuclear envelope frequently had a concavity adjacent to the vacuoles as if indented by pressure from the vacuole. 

If the diacetylene moiety is introduced into phospholipids or similar double-layered membrane and/or micelle/vesicle-forming molecular structures, these special forms of orgemisation may be polymerized as well providing a solid-like arrcungement of the reactive groups is attained. Vesicles and micelles of polydiacetylenes have been prepared in a great variety following this principle (12,16). 

Fig. 2.2 Assemblies fonned in selective solvent conditions by multiblock copol3nners (from upper left to right) Janus spheres, core-shell spheres, raspberry-like spheres, Janus cylinders, core-shell cylinders, segmented cylinders, asymmetric (Janus) membrane vesicles, double-layer membrane vesicles, vesicles with hexagonally packed cylinders. Reproduced from [3] with permission from Elsevier...

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