The present disclosure describes devices and methods capable of generating multi-phase emulsions, including double emulsion droplets in a gas phase. In one particular embodiment, the occlusion of the fallopian tubes by an intrafallopian contraceptive device may be confirmed by contrast enhanced ultrasonography. The invention furthermore relates to processes for the preparation of the compounds of the formula, their use as pharmaceuticals, and pharmaceutical compositions comprising them. A series of guiding belts are employed for circumferentially mounting on the outer surface of the reinforcing materials to form a sleeve. The actuator is rotated with reference to the pivot.