Positive-pressure gas
loading manifold (nominal pressure is 2.7
atm for a 0.5 L OP-cell), which consists of Teflon pneumatic valves
and tubing, one-way check valves, in-line O2 and Rb getters/filters,
vacuum and pressure sensors, and two exit paths: “in vivo”
(i.e., for clinical use) and “in vitro” (i.e., for experiments
not involving living organisms). Implementation of the Rb filter does
not appear to measurably impact 129Xe hyperpolarization
(ref (20)).