Molecular interchange process

Fnel when the exposure time is greater than 10 5 sec, and the gas phase is saturated. From this discussion it can be concluded that the net rate of phase change, that is, the rate of mass transfer, can be calculated from either Eq. (65) or Eq. (66) with an equal degree of accuracy. However, the absolute rates of vaporization and condensation can only be calculated from the rate expressions based on the molecular interchange process. It is shown later in this chapter that the absolute rates must be determined to describe accurately the energy transfer that accompanies phase change. 

The susceptibility of polyesters and polyamides to interchange reactions, such as may occur in the former between a terminal hydroxyl of one molecule and an interunit ester group of another, was discussed in Chapter III. These interchange processes do not decrease the number of molecules, and hence do not affect Mnj but they might permit some molecular species to be formed in preference to others. In other words, they may conceivably bring about an alteration of the molecular size distribution. 

The nucleoside dipho hatase enzyme was shown by Novikoff to be localized in the membrane of the endoplasmic reticulum of over a dozen cell types, including the five known secretory cells of the rat anterior pituitary gland (Pelletier and Novikoff, 1972). Novikoff could see no evidence for the involvement of transport ATPase or of processes of molecular interchanges between cells on their environment (Pelletier and Novikoff, 1972). 

---