Lamellae surface area

Figure 4. Cross-section of a Plante plate. The fine lamellas of the casting enlarge its surface area by a factor of 8-12. On the top, the current collector, the plate lug, is to be seen.

The BET surface area of the catalysts is summarised in Table 3. The enhancement could be explained in case of MO-s with the reconstruction of the lamella structure. The reason of enhancement in the presence of 212 is still not known. All the other cases significant decrease can be observed. The surface area of metallic part of the used RNi-s shows increase from A to C, with the increasing temperature of the catalyst production, indicating growing Ni distribution. 

The free energy of a lamella, where the fold surface area A(= L1L2) is taken to be much larger than lateral surface area (L3L1 + L2L3), follows from Eq. (1.20) as... 

The layer of water adjacent to the absorptive membrane of the enterocyte is essentially unstirred. It can be visualized as a series of water lamellas, each progressively more stirred from the gut wall toward the lumen bulk. For BCS class 2 compounds the rate of permeation through the brush border is fast and the diffusion across the unstirred water layer (UWL) is the rate-limiting step in the permeation process. The thickness of the UWL in human jejunum was measured and found to be over 500 pm [3]. Owing to its thickness and hydrophilicity, the UWL may represent a major permeability barrier to the absorption of lipophilic compounds. The second mechanism by which the UWL functions act as a barrier to drug absorption is its effective surface area. The ratio of the surface area of the UWL to that of the underlying brush border membrane is at least 1 500 [4], i.e., this layer reduces the effective surface area available for the absorption of lipophilic compounds and hence impairs its bioavailability. 

This is also evident when considering the convective entanglement of two initially vertical liquid lamellae. For the double-sided structured channel, a considerable increase in the lamellae entanglement and an enlarged interfacial surface area are observed. 

The secondary collimator ensures that only constant angle scatter reaches the detector. As indicated in Fig. 21, it consists of a series of thin lamella that are conical surfaces of resolution around the Z axis. Each of these has a surface area of 0.25 m2 and requires stabilization using a low-density foam filling and/or radial ribs positioned at regular intervals in the sense. The scatter detector and collimator shown in Fig. 21 can be replicated on both sides of the XY plane for increased signal and reduced attenuation artefacts. 

With lamellar electrodes the main idea is to decrease the voltage across the bath by increasing the electrode surface area. To this a great number of lamellae are used, held in position by spacers the whole set is then tightened together by horizontal clamping bolts. The electrode bundles so formed are inserted into the electrolyzer in such a manner so that the individual plates are... 

There is considerable evidence that oxidation and other reactions take place preferentially at the crystallite edges rather than on the flat faces of the lamellae. The scope for such reactions would be small except with very finely divided powders because the proportion of edge surface to total surface area is small, and this theory is consistent with the general stability of the disulphide. 

Foam is a disperse system with a high surface area, and consequently foams tend to collapse spontaneously. Ordinarily, three-dimensional foams of surfactant solutes persist for a matter of hours in closed vessels. Gas slowly diffuses from the small bubbles to the large ones (since the pressure and hence thermodynamic activity of the gas within the bubbles is inversely proportional to bubble radius). Diffusion of gas leads to a rearrangement of the foam stmctures and this is often sufficient to rupture the thin lamellae in a well-drained film. 

If an insoluble agent is dispersed in the liquid interior of foam lamellae, then, from thermodynamics, it can penetrate or enter the gas—liquid interface if the entering coefficient, E, is positive (originally defined (55) as a rupture coefficient, R). E is defined, for unit surface areas, as... 

The accessibility curve given in Figure 3 is effectively a cumulative pore distribution relating pore volume to pore size. With an assumption of pore shape it supplies all the information required to calculate the surface area of the pores. In previous publications we have postulated that the most basic particle shape within the cell wall is that of lamellae or sheets of microfibrils. The pores would then be the slit like spaces between these sheets as depicted in the simple model shown in Figure 4. In the model two sheets are separated by a distance w (pore width) and contain a pore volume Ao. If A A is the area of the pore bounded by the two sheets, then obviously AA/2 is the area of one face of the pore and the three quantities, A A, At , and w are related by the equation ... 

The last effect to be described here is film elasticity In case of ionic surfactants the aqueous phase in the double layers contain dissolved counter ions of the surfactants. When the ionic density increases, the repulsive forces of equally charged ions become substantial, see Fig. 11. The repulsive forces are also responsible for a certain elasticity of double layers. The thickness of double layers in the well-known coloured air bubbles lies between 1,000 and 10,000 A. It can be determined by the order of interferential colours The process is very dynamic and fluctuates over the surface area. Under certain conditions the drainage reaches an end at a metastable state (so called black films ) giving the lamella or bubble a limited time of existence ... 

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