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Transfer units, membranes

Figure 8.12 Two types of electrotransfer apparatus. At the left a tank transfer cell is shown in an exploded view. The cassette (1) holds the gel (2) and transfer membrane (3) between buffer-saturated filter paper pads (4). The cassette is inserted vertically into the buffer-filled tank (5) between positive and negative electrodes (not shown). A lid with connectors and leads for applying electrical power is not shown. On the right side of the figure is shown an exploded view of a semidry transfer unit. The gel (5) and membrane (6) are sandwiched between buffer-saturated stacks of filter paper (4) and placed between the cathode assembly (3) and anode plate (7). A safety lid (1) attaches to the base (9). Power is applied through cables (8). Figure 8.12 Two types of electrotransfer apparatus. At the left a tank transfer cell is shown in an exploded view. The cassette (1) holds the gel (2) and transfer membrane (3) between buffer-saturated filter paper pads (4). The cassette is inserted vertically into the buffer-filled tank (5) between positive and negative electrodes (not shown). A lid with connectors and leads for applying electrical power is not shown. On the right side of the figure is shown an exploded view of a semidry transfer unit. The gel (5) and membrane (6) are sandwiched between buffer-saturated stacks of filter paper (4) and placed between the cathode assembly (3) and anode plate (7). A safety lid (1) attaches to the base (9). Power is applied through cables (8).
Plate and frame systems offer a great deal of flexibility in obtaining smaller channel dimensions. Equations 4 and 5 show that the Increased hydrodynamic shear associated with relatively thin channels Improves the mass-transfer coefficient. Membrane replacement costs are low but the labor involved is high. For the most-part, plate and frame systems have been troublesome in high-pressure reverse osmosis applications due to the propensity to leak. The most successful plate and frame unit from a commercial standpoint is that manufactured by The Danish Sugar Corporation Ltd. (DDS) (Figure 15). [Pg.417]

The flux of oxygen transfer per unit membrane area /q (molorcm min cm" ) is given by... [Pg.263]

As a second possibility, lipid-protein interaction must be considered. The red shift might be explained in terms of hydrophobic interaction of the hydrocarbon chains of phospholipids with the protein in such a way that the amide chromophores are transferred to a less polar environment (89). Again, the hypothesis can be tested by removal of lipid. The existence of the red shift in lipid-depleted mitochondria and in lipid-free mitochondrial structural protein shows that lipid-protein interaction is not necessary to produce the ORD spectra characteristic of membranes. It is possible that if some molecular rearrangement occurs during the extraction process, a red shift caused by hydrophobic lipid-protein association could be replaced with a red shift arising from hydrophobic protein-protein association. Such an explanation is unlikely, especially in view of the retention of the unit membrane structure in electron micrographs taken of extracted vesicles (30). On the basis of ORD, then, the most reasonable conclusion is that the red shift need not be assigned to lipid-protein association. [Pg.278]

Figure B3.2.2 Electroblotting with a tank transfer unit. The polyacrylamide gel containing the protein(s) to be transferred is placed on the smooth side of the polyethylene sheet (or filter paper sheets) and covered with the PVDF membrane and then a single sheet of filter paper. This stack is sandwiched between two fiber pads and secured in the plastic gel holder cassette. The assembled cassette is then placed in a tank containing transfer buffer. For transfer of negatively charged protein, the membrane is positioned on the anode side of the gel. Charged proteins are transferred electrophoretically from the gel onto the membrane. Figure B3.2.2 Electroblotting with a tank transfer unit. The polyacrylamide gel containing the protein(s) to be transferred is placed on the smooth side of the polyethylene sheet (or filter paper sheets) and covered with the PVDF membrane and then a single sheet of filter paper. This stack is sandwiched between two fiber pads and secured in the plastic gel holder cassette. The assembled cassette is then placed in a tank containing transfer buffer. For transfer of negatively charged protein, the membrane is positioned on the anode side of the gel. Charged proteins are transferred electrophoretically from the gel onto the membrane.
An alternative to the tank transfer system is the semidry transfer system. In this procedure, the gel is stacked horizontally on top of the membrane in the transfer apparatus. Because only a small volume of transfer buffer is used, SDS from the gel is less effectively diluted, which may result in incomplete binding and lower yields, especially with PVDF membranes. For this reason, semidry transfer units are not recommended when reproducible high recoveries of electroblotted proteins are desired (e.g., for subsequent sequence analysis). Some procedures recommend stacking multiple transfer sandwiches to achieve several transfers simultaneously. To prevent unbound protein from migrating through the next gel and onto the membrane in the next transfer stack, sheets of porous cellophane sheets or dialysis membrane are placed between adjacent transfer stacks (see Fig. B3.2.3). Semidry electrotransfer requires shorter transfer times than tank transfer. [Pg.191]

Figure B3.2.3 Electroblotting with a semidry transfer unit. In most cases, the lower electrode is the anode, as shown. Position the Mylar mask (optional) directly over the anode. Layer on three sheets of filter paper that have been wetted in transfer buffer. For negatively charged proteins, place the preequilibrated transfer membrane on top of the filter paper followed by the gel and three additional sheets of wetted filter paper. If multiple gels are to be transferred, separate the transfer sandwiches by inserting a sheet of porous cellophane or dialysis membrane between each stack. Place the cathode on top of the assembled transfer stack(s). Transfer the proteins by applying a maximum current of 0.8 mA/cm2 gel area. Figure B3.2.3 Electroblotting with a semidry transfer unit. In most cases, the lower electrode is the anode, as shown. Position the Mylar mask (optional) directly over the anode. Layer on three sheets of filter paper that have been wetted in transfer buffer. For negatively charged proteins, place the preequilibrated transfer membrane on top of the filter paper followed by the gel and three additional sheets of wetted filter paper. If multiple gels are to be transferred, separate the transfer sandwiches by inserting a sheet of porous cellophane or dialysis membrane between each stack. Place the cathode on top of the assembled transfer stack(s). Transfer the proteins by applying a maximum current of 0.8 mA/cm2 gel area.
Disconnect the power supply from the transfer unit, disassemble the layers, and cut a notch on the PVDF membrane to mark the position of lane 6. Stain the gel following the transfer with Coomassie Blue as described in step 8. This is done to ensure that the proteins on the gel were transferred to the PVDF membrane. [Pg.298]

Earlier papers on the continuous membrane column (28,29) have discussed the separation of CO2-N2, CO2-O2 and O2-N2 (air) mixtures in stripper, enricher and total column units composed of 35 silicone rubber capillaries. A characterization of the membrane column using a membrane unit concept (analogous to transfer unit concept — HTU, NTU) has also been presented. The purpose of this paper is to present some new data and discussions on the extended study of continuous membrane column. Specifically, the topics of multicomponent separations, Inherent simulation difficulties, composition minima in the enriching section, variation of experimental parameters, and local HMU variation along the column will be covered. [Pg.260]

The performance of the continuous membrane column was characterized earlier (28) in a manner analogous to the transfer unit concept for packed columns. The expressions developed for NMU (difficulty of separation) and HMU (efficiency) were... [Pg.267]

Hydrodynamic permeability, I, is defined by permeated water across the ion exchange membrane per unit time and unit membrane area (volume transfer per unit time and unit membrane area across the membrane, V) in the presence of an hydraulic pressure difference, AP,... [Pg.28]

PEM Polymer electrolyte membrane or proton exchange membrane PTU Power transfer unit... [Pg.108]

Other procedures and calculation techniques have been developed for both stagewise and differential permeation, such as those presented S-T Hwang and K. Kammermeyer, but they are not pursued here, inasmuch as the analogy is to be made specific to vapor-liquid mass transfer unit operations. In this way, the conventions and techniques already developed for mass transfer operations can be more readily utilized. Also note that the symbols and terminology used for membrane permeation have evolved through the years and vary from one author to another. [Pg.18]


See other pages where Transfer units, membranes is mentioned: [Pg.143]    [Pg.155]    [Pg.167]    [Pg.169]    [Pg.206]    [Pg.221]    [Pg.222]    [Pg.264]    [Pg.264]    [Pg.197]    [Pg.66]    [Pg.110]    [Pg.298]    [Pg.723]    [Pg.2784]    [Pg.770]    [Pg.187]    [Pg.153]    [Pg.109]    [Pg.240]    [Pg.240]    [Pg.3]    [Pg.29]    [Pg.1008]    [Pg.2783]    [Pg.357]    [Pg.44]   
See also in sourсe #XX -- [ Pg.143 ]

See also in sourсe #XX -- [ Pg.143 ]




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