Membranes illustration

Fig. 6. Solute transport in hemodialysis. Clearance vs solute mol wt for dialy2ers prepared from the two different membranes illustrated in Figure 5. Numbers next to points represent in min /cm calculated from equations 10 and 5. Data is in vitro at 37°C with saline as the perfusion fluid. Lumen flow, dialysate flow, and transmembrane pressure were 200 ml,/min, 500 mL/min, and 13.3 kPa (100 mm Hg) area = 1.6. Inulin clearance of the SPAN...

Figure 12.16 View of the reaction center perpendicular to the membrane illustrating that the pigments are bound between the transmembrane helices. The five transmembrane-spanning a helices of the L (yellow) and the M (red) subunits are shown as well as the chlorophyll (green) and pheophytin (blue) molecules.

Diagrammatic representation of a section through the inner mitochondrial membrane, illustrating features of the chemiosmotic theory in the sequence in which they are mentioned in the song. 

Fig. 1. A simplified scheme of the photosynthetic membrane, illustrating electron transfer from water to ferredoxin, which involves three protein complexes (the PS II reaction centre, the Cyl complex, the PS I reaction centre) and two diffusible components, plastoquinone (PO pool) and plastocyanin (Pc),...

Functional groups Chapter 3 uses the functional groups to introduce important properties of organic chemistry. Relevant examples—PCBs, vitamins, soap, and the cell membrane—illustrate basic solubility concepts. In this way, practical topics that are sometimes found in the last few chapters of an organic chemisuy text (and thus often omitted because instructors run out of time) are introduced early so that students can better grasp why they are studying the discipline. 

Figure 1. The structure of lecithin represented schematically (A), as a formula (B), as a model (C), and symbolically (D). Such phospholipid bilayers are thought to constitute the basic structure of cell membranes. Illustration by Hans Cassidy. Courtesy of Gale Group. 

Figure 1. Random collisions with semi permeable membrane. Illustration by Hans Cassidy. Courtesy of Gale Group.

The flux of 0.03 gfd for the homogeneous polyamide membrane was more than two orders of magnitude too low for commercial desalination. The flux was increased 175 fold with no decrease in salt rejection by casting the membrane with asynmetric morphology. Even higher fluxes, up to 3.5 times that observed for the asymmetric MPD-l/T (100-70/30) polyamide membrane, were obtained with asymmetric membranes cast from polyhydrazides and polyamide-hydrazides. Permeation properties for the three types of aromatic polyamides are shown in Table IX. The RO properties of this group of membranes illustrate the combined effects of Structure Levels I, II and III on membrane performance. 

Figure 1.2 General structure of a cell showing the main compartments (organelles) into which the interior is partitioned. ALL ceLLs of aLL organisms are constructed from the main bioLogicaL macromoLecuLes proteins, carbohydrates, and nucleic acids together with macromolecular lipid structures that comprise the membranes, (illustration from Philip Harris Ltd, Weston Super Mare, UK).

Examine a system in which a dilute solution is separated from a concentrated solution by a semipermeable membrane, illustrated in Figure 14.23. During osmosis, water molecules move in both directions across the membrane, but the solute molecules cannot cross it. Water molecules diffuse across the membrane from the dilute solution to the concentrated solution. The amount of additional pressure caused by the water molecules that moved into the concentrated solution is called the osmotic pressure. Osmotic pressure depends on the number of solute particles in a given volume of solution and is a colligative property of solutions. 

Figure 5.1 Schematic representation of a biological membrane illustrating the barrier produced by the phospholipid bilayer.

The water content of a perfluoro sulfonic acid membrane and a perfluorocarboxylic acid membrane illustrated in Fig. 18 clearly... 

Figure 11.15 Interaction of PDKl and PKB detected by two-photon time domain FLIM. NIH3T3 are transfected with GFP-PDKl (upper panel), co-transfected with mRFP-PKB (middle panel) and stimulated by growth factor PDGF (lower panel). The lifetime maps indicate that the GFP-PDKl lifetime changes at the plasma membrane of these cells upon stimulation. In the presence of the acceptor mRFP-PKB there is no variation of the donor lifetime (GFP-PDKl) at the plasma membrane. The lifetime distributions are indicated by the histograms (right panels). It can be clearly seen that, upon stimulation, the GFP-PDKl lifetime at the plasma membrane decreases from 2.5 to 1.9 ns and the GFP-PDKl lifetime at the cytoplasm (2.3 ns) remains the same as when the acceptor is present. The decrease in lifetime at the plasma membrane illustrates that PDKl and PKB associate upon growth factor stimulation...

Membranes for UF and similar processes are made out of a very thin film with microperforations of 0.1-1 pm size. Such tiny perforation on quite a thin film would be easily damaged by the applied pressures needed to perform separation in actual operation. The ultrathin skin or film is, therefore, supported on a relatively thick (100-200 pm thick) substructure. The retention is performed over the thin film, on which the pore sizes may vary due to the manufacturing technique. Two common membrane structures are the plane membrane and the hollow fiber membrane, illustrated in Figure 10.46. 

The liquid membranes illustrated here are only used in some specific applications because of the rather low selectivities obtained. Selectivities are mainly based on differences in the distribution coefficients of the components of phase 1 with the liquid. If the components are similar these differences are generally not very high. The diffusivities of components of comparable size are similar so that the selectivity, which is determined... 

Fig. 9. Experimental setup for impedance measurements with electrochenucal control of membrane impedance platinized platinum electrodes (a) constant voltage power supply, (b) gold minigrid electrode (c) polypyrrole film, (d) 1 M KCl solution (e) constant current ac circuit, (f). At right is a microscopic view of membrane, illustrating effect of membrane potential on ionic resistance (reprinted with permission ft om Ref.

The WAXS data of vacuum-dried sealed membranes illustrate a polymer peak at 4.5 A and a shoulder peak at 3.3 A. This is an indication of the presence of water even after a long exposure to vacuum. NMR studies of these polymer membranes in our laboratories have established the presence of two types of water molecules [32]. These consist of loose water molecules that are in equilibrium with the environment and tightly-bound water molecules that are difficult to remove. 

Fig. 10.4 Stress-strain curves of BPO SPEEK membranes, illustrating the effect of the filler to matrix ratio on the tensile properties of the membranes. Tests were performed at 23°C and 30% RH. Reference [1], reprinted with permission of John Wiley Sons, Inc...

The physical picture of a reverse osmosis membrane illustrated in Figure 6.3.29b is sometimes identified as the sieve transport model one section of the membrane (fractional area Et] has pores that are completely open, i.e. nonrejecting, while the rest of the membrane (fractional area (1 — j,)) has complete rejection of the solute. However, variations in this model arise depending on the extent of solute mixing downstream of the membrane... 

Consider the composite "PRISM-type membrane illustrated in Example 6.3.14. For such a polysulfone membrane having a thin coating of silicone rubber, the values of the permeability coefficients through layers A and B for a H2-CO mixture are ... 

As mentioned in Chapter 1, the catalyst in porous MRs may just be placed on the membrane (illustrated in Figure 1.12(a)). The reaction takes place in the catalyst phase and the membrane only serves either as a product extractor or as a reactant distributor but does not participate directly in chemical reactions. It is not always easy to obtain a true inert membrane since the porous membrane materials such as alumina, silica, titania, zirconia, zeolite or the components used to modify membrane permeation properties (e.g., pore-filling materials) can make a contribution to reactions. In order to reduce non-selective catalytic activity, the membrane used in selective oxidation reactions often has to be modified significantly by using controlled sintering to reduce surface area, or by doping with alkaline compounds to decrease surface acidity [19]. 

On the basis of the data available at present, a tentative model of the E. coli outer membrane (illustrated diagramatically in Fig. 16) is postulated. This model has the following features [all numbers are calculated assuming that the cell s surface area is 4 (= 4 x 10 A )] ... 

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