Fig. 2
Changes in the (a, d) PC1 score and (b, e) superimposed PC1 score calculated from NIR second derivative spectra (6300–5450 cm−1) as a function of treatment time. Blue circle, green circle, pink circle and red circle show the score of wood samples treated at 120, 130, 150 and 180 °C, respectively. R 2 shows the determination coefficient between the measured and simulated values. (c, f) Arrhenius plot of shift factors from empirical superposition of the change of ln(a T ). Left figures show the result for thermal treatment and right figure shows the result for hygrothermal treatment. Species is hinoki