Figure shows a fiber that reacted in the Reactor free of e-beam irradiation simultaneously with the irradiated one. The length of the nanowhiskers of the irradiated nanofiber (Figure ) are only a quarter of those which grew in the non-irradiated zone (Figure ). Statistical analysis of the nanowhiskers' length of the e-beam irradiated and non-irradiated shows a factor four difference between the length of the two families (391 ± 134 nm for the non-irradiated and 92 ± 36 nm for the irradiated W18O49 nanowhiskers). This intriguing finding is attributed to the interaction of the e-beam with the growing nanowhiskers. On the one hand, the e-beam has a strong chemical reducing nature, but on the other hand, the heating effect of the e-beam cannot be absolutely excluded. Indeed, the vapor pressure of tungsten dioxide, which may be formed, is appreciably smaller that of WO3 at elevated temperatures, which may explain the lower growth rate of the e-beam irradiated W18O49 nanowhiskers. Following Experiment No. 1, a kinetic study of the growth of WO3-x nanowhiskers (analyzed later as the W18O49 phase, see Figure ) on the surface of the e-beam-irradiated -WO3/a-SiO2 nanofiber in the Reactor within the SEM was undertaken. For a detailed discussion of the kinetic analysis see Supplementary Discussion 1. Experiment No. 2, dedicated to the partial reduction of -WO3/a-SiO2 nanofibers at 900 °C under vacuum (10 -3 Pa, i.e. 10 -5 Torr) is described in detail in Supplementary Discussion 2 and visualized in Video 2.