A mailing machine base includes a docking system for a User Interface Controller that provides a feedback signal to the mailing machine based on the presence of the UIC. Its use for the production of microgels is also described. The imaging can be performed utilizing low-energy beam techniques such as scanning electron microscopy; however, more sophisticated imaging techniques can also be employed. Each of the separators has a porous substrate and porous coating layers formed on both surfaces of the porous substrate. The timing recovery system in each receiver independently phase-aligns and frequency synchronizes the sampling signal to the serial data signal associated with the receiver.