Nodal ring

Alternatively, it may be related to the thickness of sensory and motor nerves, as well as to the distance between nodes of Ranvier. In saltatory impulse conduction, only the nodal membrane is depolarized. Because depolarization can still occur after blockade of three or four nodal rings, the area exposed to a drug concentration sufficient to cause blockade must be larger for motor fibers (p. 205B). 

The phenyl cation is an extremely unstable cation, as is reflected by the high hydride affinity shown in Table 5.2. In this case, the ring geometry opposes rehybridization so the vacant orbital retains sp character. Because the empty orbital is in the nodal plane of the ring, it receives no stabilization firom the n electrons. 

The HOMO-1 is localized on the central rings and has no contribution from the phenyl rings. There are nodal planes running perpendicular to the viewing plane every 45 degrees. There is another nodal plane that is the molecular plane. 

Other systems studied include the spiroheptadiene system (13) in which the cyclopropane moiety lies in the nodal plane of the butadiene HOMO [1 2,9 10]bis-methano[2.2]paracyclophane (15), in which two cyclopropane moieties are joined with two benzene rings in such a way that tertiary-tertiary cyclopropane bonds lie parallel to the aromatic n system 7-methylenequadricyclane radical cation (16 ), in which a pair of cyclopropane groups lie orthogonal to an olefinic moiety and the 7-spirocyclopropanenorbomadiene radical cation (18 ), in which a pair of nonconjugated ethene groups and a cyclopropane moiety are joined. 

This refers lo nodal planes perpendicular lo Ihe plane of Ihe ring The ring ilsclf must he a nodiii plane since ihe it system is constructed (rum atomic p orbuals. 

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