Network thermodynamics

Mikulecky, D. C. (1993). Applications of Network Thermodynamics to Problems in Biomedical Engineering . New York University Press, New York. 

Since about 1989, Homo and coworkers have published a series of papers on their network thermodynamic method of simulation. Only a few of these will be cited here. In the first, the 1989 work, the method is described [309], and again in 1992-4 [271,305,306], adding cyclic voltammetry. In the 1994 paper [305], there is a good description of the method, and an indication how it can be adapted to a multitude of different electrochemical systems. A Chinese group has also used this method [205,208,209,210]. 

The ultimate example studied in this chapter is the mitochondrial respiratory system and oxidative ATP synthesis. This system, in which biochemical network function is tightly coupled with membrane transport, is essential to the function of nearly all eukaryotic cell types. As an example of a critically important system and an analysis that makes use of a wide range of concepts from electrophysiology to detailed network thermodynamics, this model represents a milestone in our study of living biochemical systems. To continue to build our ability to realistically simulate living systems, the following chapter covers the treatment of spatially distributed systems, such as advective transport of substances in the microcirculation and exchange of substances between the blood and tissue. 

Introducing the chemical potential (or free energy) and the thermodynamic constraint provides a solid physical chemistry foundation for the constraint-based analysis approach to metabolic systems analysis. Treatment of the network thermodynamics not only improves the accuracy of the predictions on the steady state fluxes, but can also be used to make predictions on the steady state concentrations of metabolites. To see this, we substitute the relation between reaction Gibbs free energy (ArG ) of the th reaction and the concentrations of biochemical reactants... 

Network thermodynamics can be used in the linear and nonlinear regions of nonequilibrium thermodynamics, and has the flexibility to deal with complex systems in which the transport and reactions occur simultaneously. The results of nonequilibrium thermodynamics based on Onsager s work can be interpreted and extended to describe coupled, nonlinear systems in biology and chemistry. 

Network thermodynamics with bond graph methodology... 

The network thermodynamics model has been applied to understand the effects of diffusion coupling in the membrane transport of binary flows. In the formalism of network thermodynamics, a membrane is treated as a sequence of discrete elements called lumps, where both dissipation and storage of energy may occur. These lumps are joined in the bond graphs, and have a resistance R, and capacitance (volume) C, which are defined by... 

Figure 14.3. Network thermodynamic model with bond graph fora single-component flow system.

The bond graph method of network thermodynamics is widely used in studying homogeneous and heterogeneous membrane transport. Electroosmosis and volume changes within the compartments are the critical properties in the mechanism of cell membrane transport, and these properties can be predicted by the bond graph method of network thermodynamics. In another study, a network thermodynamics model was developed to describe the role of epithelial ion transport. The model has four membranes with series and parallel pathways and three transported ions, and simulates the system at both steady-state and transient transepithelial electrical measurements. 

Network thermodynamics has also been applied to nonstationary diffusion through heterogeneous membranes concentration profiles in the composite membrane and change of the osmotic pressure have been calculated with the modified boundary and experimental conditions. 

A model of a biphasic enzyme membrane reactor for the hydrolysis of triglycerides has been formulated according to the bond graph method of network thermodynamics, and the kinetics, the permeabilities of fatty acids and glycerides, the rates of inhibition of the immobilized enzyme, and the concentration of enzyme in a reaction zone are studied. 

R. Paterson, Network Thermodynamics, in E.E. Bitter, Ed., Membrane Structure and Function, Vol. 2, Wiley, New York (1980). 

L. Peusner, Studies in Network Thermodynamics, Elsevier, Amsterdam (1986). 

In the absence of a network, thermodynamic quantities can be evaluated much more reliably at present, the best approach would therefore be to work where possible with model systems in which the molecular changes correspond to those in junction formation (see Section IV,lg p. 312). 

Simon, A.M., Doran, R, and Paterson, R. 1996. Assessment of diffusion coupling effects in membrane separations. Part I. Network thermodynamics modeling. J. Membr. Sci. 109 231. 

The bond-graph method of network thermodynamics is widely used in studying homogeneous and heterogeneous membrane transport. Electroosmosis and volume changes within the compartments are the... 

G. F. Oster, A. Perelson, A. Katchalsky, Network thermodynamics, dynamic modeling of biophysical systems,... 

The first question was answered by Network Thermodynamics (e.g. Oster et al., 1973 Schnakenberg, 1977 Peusner, 1985) adopting the bond graph technique. This approach benefits from the formal correspondence between certain interpretations of nonequilibrium thermodynamics and of electrical network theory. Adopting the notions of chemical impedance , chemical capacity and chemical inductance , chemical reactions as well transport processes can be represented by networks obeying KirchhofFs current and voltage laws. 

Peusner, L. (1985). Studies in network thermodynamics. Elsevier, Amsterdam. 

Abstract Fuel cells are environmentally friendly futuristic power sources. They involve multiple energy domains and hence bond graph method is suitable for their modelling. A true bond graph model of a solid oxide fuel cell is presented in this chapter. This model is based on the concepts of network thermodynamics, in which the couplings between the various energy domains are represented in a unified manner. The simulations indicate that the model captures all the essential dynamics of the fuel cell and therefore is useful for control theoretic analysis. 

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