Figure 3. Temperatures recordings by two thermocouples (Akzo Instrumentos, Brazil), one inserted in a control straw in position 5 of the device and the second in ambient air. Three cooling periods are monitored: 1) for 20 min in a refrigerator, 2) for ten minutes in an expanded polystyrene container containing liquid nitrogen, the support is then in fluctuation mode, 3) for a variable period in liquid nitrogen (LN2) the straws being then released from the support.