Active transport, design principles

Lehn and coworkers also discussed the principles of design of self-assembling helical structures on the basis of conformational control. Depending on the solvent used, they were able to obtain helicate fibers and bundles possessing extended molecular channels characterized by hollow cores of limited diameter ofca. 8 A. This finding could form the basis of functional materials for multichannel ion active transport [28]. 

Transport is a three-phase process, whereas homogeneous chemical and phase-transfer [2.87, 2.88] catalyses are single phase and two-phase respectively. Carrier design is the major feature of the organic chemistry of membrane transport since the carrier determines the nature of the substrate, the physico-chemical features (rate, selectivity) and the type of process (facilitated diffusion, coupling to gradients and flows of other species, active transport). Since they may in principle be modified at will, synthetic carriers offer the possibility to monitor the transport process via the structure of the ligand and to analyse the effect of various structural units on the thermodynamic and kinetic parameters that determine transport rates and selectivity. 

The successful development of electrochemical processes for some of the cited reactions requires an understanding not only of surface interactions but also of the changes in activity and selectivity that may incur from cell design, mixing, potential or current distribution, and transport processes. Here, we shall examine some simple reaction engineering principles that would be helpful for elucidating these effects. 

Modeling a chemical process is a very synthetic activity, requiring the use of all the basic principles of chemical engineering science, such as thermodynamics, kinetics, transport phenomena, etc. For the design of controllers for chemical processes, modeling is a very critical step. It should be approached with care and thoughtfulness. 

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