Principal behind the nano-TA-SPM system. (A) Position of cantilever and form change of a cell upon heating. Stage A, the initial heating stage: the coefficient of linear expansion increases, α > 0, and the cell expands at a constant rate. Stage B, the heating stage: the coefficient of linear expansion increases more slowly than stage A, Stage C, the maximum expansion stage: the coefficient of linear expansion has stopped, α = 0, and this temperature is the transition temperature Tg of the coefficient of linear expansion [°C]. Stage D, the ruptured stage: the coefficient of linear expansion decreases, α < 0, and the shape of the heated cell or spore is destroyed. Z0 is the height at the start of heat application, and z max is the height when the transition temperature is reached. (B) The distortion due to expansion after hanging a constant stress from the axial top of Z-value and heating the cell or spore. The change in the physical properties due to heating have occurred when the height = 0 (height Z0 in (A)). Stage A is from t
, where α is constant; stage B is from t
to Tg; stage C is the transition temperature Tg of the coefficient of linear expansion; and stage D is where α < 0 and decreases, the cell fuses, and its shape is destroyed. (C) Changes in the surface form of spores before and after heating, (a) nano-TA image and cross-sectional diagram of B. subtilis before heating, (b) nano-TA image and cross-sectional diagram of B. subtilis heated to the transition temperature (Tg = 125°C). Red circle shows the change in form as the cell reaches the transition temperature, where expansion due to heating is maximum (coefficient of linear expansion = 0) and the cell partially fuses.