In discontinuous systems

It is important to bear in mind that an electrophoresis gel is an element in an electrical circuit and as such obeys the fundamental laws of electricity. Each gel has an intrinsic resistance, R, determined by the ionic strength of its buffer (R changes with time in discontinuous systems). When a voltage V is impressed across the gel, a current I flows through the gel and the external circuitry. Ohm s law relates these three quantities V = IR, where V is expressed in volts, I in amperes, and R in ohms. In addition, power P, in watts, is given by P = IV. The generation of Joule heat, H, is related to power by the mechanical equivalent of heat, 4.18 J/cal, so that H = (PI4.18) cal/sec. 

In the presence of hydrophilic synthetic polymers such as PEG, the apparent rate of enzyme inactivation can be reduced a 200-fold increase of enzyme lifetime has been reported in some cases [36]. This aspect can reduce catalyst requirements and improve turnover and economical feasibility of the process. In continuous reactors treating phenolic compounds, the inactivation rate is reduced and the presence of additives has less beneficial effects than in discontinuous systems. This is due to the decreased reaction rate and, hence, decreased production rate of phenoxy radicals. Even so, the presence of PEG reduces the retention time required [81]. 

Amino adds, peptides, and proteins are analyzed by a variety of modes of capillary electrophoresis (CE) which employ the same instrumentation, but are different in the mechanism of separation. A fundamental aspect of each mode of CE is the composition of the electrolyte solution. Depending on the specihc mode of CE, the electrolyte solution can consist of either a continuous or a discontinuous system. In continuous systems, the composition of the electrolyte solution is constant along the capillary tube, whereas in discontinuous systems, it is varied along the migration path. 

In discontinuous systems, intensive state variables have the same value throughout in each sub-system. But the same are discontinuous at the boundary of homogeneous... 

Although networks originally were intended as a language for describing processes particularly in discontinuous systems, they may also be utilized to derive equations for continuous systems in a very consistent and transparent way. As an example, let us derive the so-called Nernst-Planck equations for ionic transport in continuous media from a network construction for the underlying elementary processes. Before going into the details of the derivation we should mention that the Nernst-Planck... 

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