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.
Hose clamp. For a long clamp with a pipe as an integral component, see Pipe clamp. Screw/band hose clamps. A hose clamp or hose clip is a device used to attach and seal a hose onto a fitting such as a barb or nipple.