:I don't know what I was exactly thinking with intrinsic repulsion-- I was seeing the pi electrons on each of the carbonyl systems repel each other somehow ( hence why they are not on the same plane )-- maybe because they are both EWGs withdrawing from each other, and this is a mutually repulsive interaction.
32.
Three basic factors contribute to the stability of individual atropisomers : the repulsive interactions ( e . g ., steric bulk ) of substituents near the axis of rotation, the length and rigidity of the single bond, a largely sp 2-sp 2 type of bond joining the aryl rings, and whether there are photochemical or other mechanisms to induce rotation in addition to thermal pathways.
33.
Notch regulates " HES1 ", which sets up the caudal half of the somite . " Notch " activation turns on " LFNG " which in turn inhibits the " Notch " receptor . " Notch " activation also turns on the " HES1 gene " which inactivates " LFNG ", re-enabling the " Notch " receptor, and thus accounting for the oscillating clock model . " MESP2 " induces the " EPHA4 " gene, which causes repulsive interaction that separates somites by causing segmentation . " EPHA4 " is restricted to the boundaries of somites . " EPHB2 " is also important for boundaries.
