The present invention relates to an optical device having a passive alignment frame with an opening therethrough. The cement head permits selective launching of darts, setting plugs, balls or other objects which can be held in place within the cement head without being damaged or washed away by slurry flow, but which can be beneficially launched into said slurry flow at desired point during the cementing process. The undiluted hydrocarbon fuel supply is passed through a nickel reactant desulfurizer bed wherein essentially all of the sulfur in the organic sulfur compounds reacts with the nickel reactant, and is converted to nickel sulfide, while the desulfurized organic remnants continue through the remainder of the fuel processing system. A verification is made that the desired nerve is being stimulated by the first level of ultrasonic energy. Such compounds may be used in combination with a chemotherapeutic agent andor a potentiator.