A process for preparing an emulsion or a dispersion comprising crystalline particles of at least one active principal that comprises contacting a solution of at least one solute in a solvent or mixture of solvents in a first flowing stream with a non-solvent in a second flowing stream wherein the non-solvent and solvent are not miscible with each other, so as to form an emulsion or a dispersion. The invention includes the attenuated viruses made by this method, antibodies generated using these viruses, and vaccines that can be used for immunizing cattle. These methods and apparatus include preload monitoring devices whereby the mechanic can accurately monitor and regulate the preload to a bearing or bearing assembly. The apparatus also includes a substrate table for holding a substrate, a projection system for projecting the patterned beam onto a target portion of the substrate, and a high voltage conductor in a part of the apparatus that is evacuated or at a low pressure during normal use of the apparatus.