A USB circuit device prevents reverse current while complying with USB specifications. The workspace has an opening permitting user ingress and egress, and the partition has a height lower than a ceiling height to form a gap between a top edge of the partition and a ceiling. The example implementation further includes an indicator element adjacent the feeler portion and coupled to the elastic shaft, wherein the indicator element projects from the cartridge chamber when the feeler portion is displaced by a cartridge. The reference object serves as the standard for the process. An example application is a graphic-based programming tool used to generate screens and their underlying program logic. The sample plate shows excellent selectivity for glycoprotein, and can be easily and cost effectively prepared.