Membrane flow

There is a substantial weight of evidence for the cytoskeleton being responsible for the force production and control of cell locomotion. This view has not yet been accepted unanimously. However, an alternative hypothesis continues to be argued which states that membrane cycling is the motive force driving cell locomotion (Bretscher, 1987). One of the predictions of the membrane flow hypothesis is that there should be a discernible flow of lipid from the front to the rear of the cell. Lipid flow has proven very difficult to study, because of the lack of suitable methods to label single lipid molecules and the heterogenous behavior of membrane-associated proteins. The observation that particles were transported rearward when they bound... 

The images obtained from the SPAN module (Figure 4.6.3(c and d)) show completely different characteristics compared with those from the SMC module. Noticeable features are the dense and evenly packed capillary membranes and the lower quality and inhomogeneities in the images. As already discussed for the ID profile (Figure 4.6.2(b)), both intra- and inter-membrane flow seems unhindered... 

MorreDJ, Keenan TW. Membrane flow revisited. Bioscience 1997 47 489-498. 

Silicone membranes, flow through, 15 722— 723. See also Membrane processes Silicone monomers, synthesis of,... 

Figure 20.24. Membrane flow cell (a) Flat-sheet (b) Cross-corrugated form(37)...

Saksa DJ, Smart RB. 1985. Chemiluminescent analysis of chlorine dioxide with a membrane flow cell. Environ Sci Technol 19 450-454. 

Porous supports like agarose, pol3mrethacrylate, or silica beads are generally used in current applications of affinity chromatography. However, in the past several years other types of supports have also become available commercially. Many of these newer materials have properties that give them superior performance in certain applications. Materials that fall in this category include nonporous supports, membranes, flow-through beads, continuous beds and expanded-bed particles. 

Morr6, D. J., Kartenbeck, J. and Franke, W. W. 1979. Membrane flow and interconversions among endomembranes. Biochim. Biophys. Acta 559, 71-152. 

The final colligative property, osmotic pressure,24-29 is different from the others and is illustrated in Figure 2.2. In the case of vapor-pressure lowering and boiling-point elevation, a natural boundary separates the liquid and gas phases that are in equilibrium. A similar boundary exists between the solid and liquid phases in equilibrium with each other in melting-point-depression measurements. However, to establish a similar equilibrium between a solution and the pure solvent requires their separation by a semi-permeable membrane, as illustrated in the figure. Such membranes, typically cellulosic, permit transport of solvent but not solute. Furthermore, the flow of solvent is from the solvent compartment into the solution compartment. The simplest explanation of this is the increased entropy or disorder that accompanies the mixing of the transported solvent molecules with the polymer on the solution side of the membrane. Flow of liquid up the capillary on the left causes the solution to be at a hydrostatic pressure... 

In the membrane flow model of Fig. 1-7, membranes move through the cell from ER—> Golgi apparatus— secretory vacuoles— plasma membrane. In the membrane shuttle proposal, the vesicles shuttle between ER and Golgi apparatus, while secretory vacuoles shuttle back and forth between the Golgi apparatus and the plasma membrane. 

As to membrane flow properties, they can be estimated through permeability constant value Pc. ... 

FIGURE 8.22 Schematics of membrane flow channel equipped flow deflector. 

In radioactive waste treatment, significant operational aspects include the following. Since the operation requires the use of high pressures, there is a need to ensure control of the activity release from possible leaks. As with evaporation, pretreatment of the feed may be necessary to prevent scaling, and where dirty waters are to be fed directly it would be advisable to consider the use of equipment with larger membrane flow channels, which would permit periodic foam ball cleaning of the membrane surface. 

---