Flow mosaic model

Miyazawa et al. (92) related rates of decrease of aliphatic hydrogen protons during pyrolysis of ethylene tar pitch to formation of mesophase. Yokono et al, (93) used the model compound anthracene to monitor the availability of transferable hydrogen. Co-carboniza-tions of pitches with anthracene suggested that extents of formation of 9,10-dihydroanthracene could be correlated with size of optical texture. The method was then applied to the carbonization behaviour of hydrogenated ethylene tar pitch (94). This pitch, hydrogenated at 573 K, had a pronounced proton donor ability and produced, on carbonization, a coke of flow-type anisotropy compared with the coarse-grained mosaics (<10 ym dia) of coke from untreated pitch. 

In mosaic nonequilibrium thermodynamics formulations not all the flows are dependent on all the fiee-energy differences, mainly because only a subset of catalytic components affects each flow relation. In this respect, the models differ from classical nonequilibrium thermodynamics where all flows are a function of all forces. 

The model system described above remains anyhow a simplified model for epithelia, as it neglects diffusive phenomena in the inner compartment and the possibility of coupling between the passive and active solute flows, which can be excluded only in mosaic membranes. In any case the results seem useful in order to explain the experimental data and to obtain a better control of the experiments. In effect, the variability of the filtration, ultrafiltration and apparent reflection coefficients which appear to be a function of both the experimental conditions and of the activity of the epithelia, imposes to be very careful in programming the experiments and when comparing the values existing in literature, often determined in poorly defined conditions. 

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