Carbocations are species bearing a formal + charge on carbon. The have sp2 hybridization and trigonal planar geometry, with an empty p orbital on carbon, perpendicular to the plane containing the substituents (see diagrams shown to the right).
Aortic cross-clamp. An aortic cross-clamp is a surgical instrument used in cardiac surgery to clamp the aorta and separate the systemic circulation from the outflow of the heart. An aortic cross-clamping procedure serves, for example, in the repairing of coarctation of the aorta.
As beam hooks the points of the two blades are hooked into an overhead beam and a weight such as an animal's limb hung from the connecting chain. The animal's weight ensures that the clamp bites deeply. silage clamp. a mass of ensilage held together at the sides between solid walls but open at the ends. surgical clamp.