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.
A short pipe clamp. A pipe clamp is a type of clamp often employed in woodworking, piping or cabinet shops. When referring to woodwork or cabinet shops, pipe clamps are usually composed of commercially manufactured clamp heads or jaws and a length of common threaded pipe. The capacity of the clamp is determined by the length of the pipe used.