FIG 10.

Influence of heat on the nanomechanical properties of the spore section, including the core, cortex, and coat. The spore section was imaged at elevated temperatures from 20 to 55, 90, 125, 160, 195, 230, 265, 300, and 335°C using the heated AFM tip before it was cooled to 20°C in air. The average dwelling time at each contact point is about 0.5 ms, corresponding to about 8 min for a whole-image scan. The modulus error bars for the coat and cortex (not shown) were comparable with those for the core. The adhesion error bars for the coat and the cortex (not shown) were significantly smaller than those for the spore core. The following AFM parameters were used: scan size, 2.1 μm; scan rate, 1 Hz; number of samples/line, 512; line direction, retrace; capture direction, down; scan angle, 0°; control gain, 18; amplitude set point, 11.5 nN; drive amplitude, 120 nm at 2 kHz; spring constant, 2.5 N/m; tip radius, 30 nm.