Intervening region

As we have already seen, accidental equivalence could be responsible for the theoretically nonequivalent protons of an AB system presenting as a singlet and for the more complex ABX system presenting as a simple doublet and triplet. But occasionally, even more interesting manifestation of accidental equivalence can be observed. Consider the molecule below (Structure 6.10) and its spectrum (Spectrum 6.6) which shows only the regions of interest to us - expanded and with the intervening region removed. 

But if diffusion rates are too slow the activation energy of chemical reaction would not have any role in the progress of reaction and we would have a situation where the progress of reaction is Diffusion Controlled." In intervening regions where both chemical reaction rate and rates of diffusion have influence on overall progress of reaction we say that the reaction progress is in the "Mixed Control" domain. 

Using the Grashof and the Reynolds numbers, we can indicate whether forced or free convection dominates in a particular case. Because Re equals inertial forces/viscous forces (Eq. 7.19) and Gr equals buoyant x inertial forces/(viscous forces)2 (Eq. 7.20), Re2/Gr equals inertial forces/buoyant forces. Thus Re2/Gr reflects forced convection/free convection. Experiments reveal that forced convection accounts for nearly all heat transfer when Re2/Gr is greater than 10, free convection accounts for nearly all heat transfer when Re2/Gr is less than 0.1, and the intervening region has mixed convection (i.e., both forced and free convection should then be considered, especially for Re2/Gr near 1). Using Equations 7.19 and 7.20, we obtain... 

Schematic drawing showing production of eukaryotic mRNA. The primary transcript is capped before it is released. Then its 3 -OH end is modified, and finally the intervening regions are excised. MeG, 7-methylguanosine. Two nucleotides whose riboses may be methylated.

Fig. 3 Keapl functional domains. Schematic overview of the three major fimctional domains in the mouse Keapl protein, with each domain labeled. BTB, bric-a-brac/tram-track/broad complex IVR, intervening region DGR, double glycine repeat. The scale at the top of the panel indicates 50 amino acid sections of the protein. The position of each cysteine residue in the protein is indicated.

IVR 179-321 Intervening region Cysteine-rich (6.3% of amino acids) ... 

---