Interstitial channel

In order to explain all the salient features of the key experimental results on ECT (viz. listed as 1. to 6. at the beginning of Section II, Phenomenology of ECT), Vijh25 proposed a detailed electrochemical mechanism in which electroosmosis of the tissue (and thence water movement from anode to cathode) and electrode reactions (thence necrosis of the tissue, pH changes etc.) play the dominant roles. In particular, he presented a model and some quantitative considerations that delineate Nordenstrom s idea of electroosmosis through the narrow interstitial channels lined with fixed charges as the mechanism of the electrochemical destruction of the tumor tissue.10 Also he examined the role of electrode reactions and other events as possible contributory factors, as follows25 in Section III.2. 

Figure 8. Electroosmosis depicted in the negatively charged tumor tissue wall enclosing an interstitial channel carrying extracellular liquid the water movement follows the direction of the field, i.e., always from the anode to the cathode.25...

The differential mass balance of the solute in the interstitial channels of the packed column can be described by... 

If retention is only due to the solubility mechanism, the initial conditions of analyses must be such that the polymer precipitates from the injected solution. In general, the sample is injected at ambient temperature. If the possibly differing column temperature does not cause precipitation, the latter must be obtained by (partly) exchanging sample solvent for nonsolvent from the running eluent. This should happen in the uppermost part of the column. Such a process is straightforward if narrow-pore packings are used and the initial eluent is a nonsolvent. Provided that the polymer is too bulky for penetration into the pores, it is restricted to the interstitial channels, whereas the solvent from the sample can exchange freely with the nonsolvent in the pores. 

Figure 2 Projection in the ac plane of the inclusion compound (6)4-(benzene) showing several host molecular staircases (hexagonal projection). The guest molecules occupy interstitial channels between these staircases. Host hydrogen atoms are omitted for clarity. In this figure, and subsequent ones, the opposite enantiomers are indicated by white or black carbon atoms, and the atom designators N (horizontal hatching) and Br (diagonal hatching), are used.

Figure 1.13 illustrates flow through a bed packed with porous particles and ui and U2 are the EOF velocities through the small intraparticle pores and the larger interstitial channels, respectively. For pressure driven flow, assuming that the path length and the pressure drops are the same for the two cases the flow velocity varies as square of... 

In the less turbulent flow through the straight channel of a monolith, momentum transfer from the fluid to the wall is less effective and in the case of two-phase, countercurrent annular flow, momentum transfer between gas and liquid will also be less than in the interstitial channels of a packed bed. The lower rates of momentum transfer, which is the reason for the higher permeability of monoliths, should in principle improve the possibility for achieving countercurrent flow of gas and liquid at realistic velocities. 

Causes for deviations from ideal plug flow are molecular diffusion in the gas and dispersion caused by flow in the interstitial channels of the bed, and uneveness of flow over the cross section of the bed. 

Molecular diffusion in the gas and dispersion resulting from flow through the interstitial channels cause a spread in residence time that can be described by an apparent diffusivity in longitudinal direction (i.e., the direction of the gas stream in the bed), j. 

Talapatra, S., Zambano, A.Z., Weber, S.E., and Migone, A.D. (2000). Gases do not adsorb on the interstitial channels of closed-ended single-waUed carbon nanotube bundles. Phys. Rev. Lett., 85, 138-41. 

As is discussed in some detail in Chapter 9 in this book, there are three possible groups of adsorption sites on a nanotube bundle of close-ended tubes the grooves, the interstitial channels (ICs) and the outer sites (OSE). The grooves are the convex valleys formed in the region on the outside surface of the bundle where two nearest neighbor tubes come closest together the IC is the open space encircled by three nearest neighbor tubes at the interior of a bundle and, the OSE are the outer surface of individual tubes located on the external surfiice of the bundle (see Chapter 9 in this book) [41]. 

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