Iris sphincter muscle Iris sphincter muscle The iris sphincter muscle (pupillary sphincter, pupillary constrictor, circular muscle of iris, circular fibers) is a muscle in the part of the eye called the iris. It encircles the pupil of the iris, appropriate to its function as a constrictor of the pupil. It is found in vertebrates and some cephalopods. Initially, all the myocytes are of the smooth muscle type but, later in life, most cells are of the striated muscle type. Its dimensions are about 0.75 mm wide by 0.15 mm thick. In humans, it functions to constrict the pupil in bright light (pupillary light
Colored smoke from aircraft was originally based on a mixture of 10-15% dye, 60-65% trichloroethylene or tetrachloroethylene, and 25% diesel oil, injected into the exhaust gases of the aircraft engines. Most commonly, teams now use specifically prepared liquid dyes and only gas oil, light mineral oil or a food grade white oil without harmful chlorinated solvents. Some mixtures used for production of colored smokes contain these dyes: Colored smoke Colored smoke is a kind of smoke created by an aerosol of small particles of a suitable pigment or dye. Colored smoke can be used for smoke signals, often in a military context.