Выражение встречается в следующем контексте:
Речь об устройстве для электрофореза,но термин скорее общетехнический.

Buffer recirculation is sometimes necessary for extended electrophoretic runs or for use with certain weak buffer systems.
To recirculate electrode buffer from the lower to the upper chambers, a few simple modifications have to be made to the PROTEAN II xi cell.

1. Locate the recirculation port tabs on the lid of the cell. The tab directly above the upper
buffer chamber and one of the tabs directly above the lower buffer chamber must be
removed. Remove by grasping with a pair of pliers and twisting the tab until it breaks
off (see photo).
2. Locate the punch out tab in the upper right corner on both sides of the central cooling
core.
Carefully bore one of the thin membrane tabs with a drill and 1/4 in (6 mm) bit.

Заранее спасибо