Extended time range modeling of myelin growth.

When some poorly water-soluble solid surfactants are contacted with water, several microstructures are observed as part of the dissolution process of the surfactants in water. One such microstructure called "myelin," which is observed when a surfactant like phosphatidylcholine is contacted with water, is the subject of this paper. In this study we have used video microscopy to investigate myelin growth over a wide time range, namely 0.25-700 s, and found that existing models do not correctly express myelin growth over extended time ranges. When studied over a wide time range, the myelin growth was found to evolve over three distinct regimes, namely ballistic, diffusional, and subdiffusional regimes. The underlying growth models are physically explained and mathematically expressed. A relationship is derived between the width of myelin and the growth rate at long times. The estimated width of myelin is consistent with experiments.