The X-ray beam is attenuated to a higher degree. by calcium, therefore less photons pass through. bone to the detectors, resulting in its âwhiteâ. appearance on CT. White matter is less cellular, contains myelinated. axons (fat), and has a higher water content than. gray matter, resulting in slightly lower.
The piston ring (PR) is a split band pressed against the wall of the cylinder by springs (S) mounted in the inner junk ring (JR). The tongue (T) maintains the seal as the ring expands and splits apart. Spring-loaded piston rings. A pair of piston rings mounted on a 47mm two-stroke cycle scooter piston.A piston ring is a split ring that fits into a groove on the outer diameter of a piston in a reciprocating engine such as an internal combustion engine or steam engine. Sealing the combustion chamber so that there is no transfer of gases from the combustion chamber to the crank. 2  Supporting heat transfer from the piston to the cylinder wall. 3  Regulating engine oil consumption.
For other uses, see Obturator. Obturator rings are a specific type of piston ring used in World War I aero engines to compensate for warping of the cylinders.he rotary aircraft engines of World War I (engines with the crankshaft fixed to the airframe and rotating cylinders) were notoriously difficult to keep cool when operating. Thus, their very thin walled steel cylinders would become distorted to an unacceptable level.