Inside-outside ring system

Fig. 2 Bond lengths (in A, shown outside the rings) and bond angles (shown inside the rings) of monocyclic six-membered aromatic systems with one heteroatom from groups 14-15 and periods 2-4 devoid of electrical charges...

FIGURE 4-10 Myelin formation in the peripheral nervous system. (A) The Schwann cell has surrounded the axon but the external surfaces of the plasma membrane have not yet fused in the mesaxon. (B) The mesaxon has fused into a five-layered structure and spiraled once around the axon. (C) A few layers of myelin have formed but are not completely compacted. Note the cytoplasm trapped in zones where the cytoplasmic membrane surfaces have not yet fused. (D) Compact myelin showing only a few layers for the sake of clarity. Note that Schwann cell cytoplasm forms a ring both inside and outside of the sheath. (Adapted with permission from Norton, W. T. The myelin sheath. In E. S. Goldensohn and S. H. Appel (eds), Scientific Approaches to Clinical Neurology. Philadelphia Lea Febiger, 1977, pp. 259-298.)... 

The canister adapter sleeve must be placed on each canister before the system can transfer it from station to station. The canister adapter sleeve is made from Delrin and has an inside diameter sized to fit a particular aerosol container and valve. An O-ring or hp-type seal helps to centre and restrict relative motion of the canister within the sleeve. The outside shape and dimensions are constant for each canister size. 

The diatropism of diazapyraceheptylenes (106), which follows from a comparison of the PMR spectra with that of 105a (Table VI), may be due to the effect of the cyano groups on the electronic configuration of the 7r-system. The chemical shift difference between the inside and outside protons clearly reveals the expected diamagnetic ring current in the annulene derivatives (110). The coupling constants of the seven-membered rings of 110 show that this part of the molecule is planar and delocalized. 

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