Disclosed herein is a method of initiating oxygen scavenging in a packaging article comprising an oxygen scavenging polymer. The evaporating heat-exchange tube comprises a smooth surface portion, a finned portion provided with plurality of fins and a transitional portion connecting the smooth surface portion to the finned portion, with primary evaporating chambers defined between the fins. A tube defining a fluid-flow path for the amount of fluid is between the expandable device and the collapsible reservoir. In the improved AP-pinned structure each of the ferromagnetic layers has a thickness greater than 30 \u212b, preferably greater than approximately 50 \u212b, and the APC layer is either Ru or Ir with a thickness less than 7 \u212b, preferably about 5 \u212b or less. The processed events are used to generate a playback file which is used by a channel emulator to perform testing.