The surface chemistry and the morphology of SnO2 nanowires, deposited by Vapour Phase Deposition (VPD) method on Au-covered silicon substrate, were studied before and after subsequent air exposure. For this purpose, surface-sensitive methods including X-ray Photoelectron Spectroscopy (XPS), Thermal Desorption Spectroscopy (TDS) and the Scanning Electron Microscopy (SEM) were applied. The studies presented within this paper allowed to determine the surface non-stoichiometry combined with the presence of carbon contaminations, in a good correlation with the surface morphology. The relative concentrations of the main components [O]/[Sn]; [C]/[Sn]; [Au]/[Sn] together with the O – Sn; O – Si bondings were analyzed. The results of TDS remained in a good agreement with the observations from XPS. Moreover, conclusions obtained for SnO2 nanostructures deposited with the use of Au catalyst were compared to the previous obtained for Ag-assisted tin dioxide nanowires. The information obtained within this studies are of great importance for the potential application of SnO2 nanowires deposited on Au covered Si substrate in the field of novel chemical nanosensor devices, since the results can provide an interpretation of how aging effects influence gas sensor dynamic characteristics.

Global warming is increasing the frequency and intensity of compound drought-heat events (CDHEs), potentially leading to larger and more extreme fire seasons in mesic forests. Wildfire activity in subtropical China, under the influence of monsoonal rainfall, was historically limited to dry winters and rare in rainy summers. Here we seek to test that this area is on the brink of a major change in its fire regime characterized by larger fire seasons, extending into the summer, leading to increases in burned area. We analyze fire activity in Chongqing Municipality (46,890 km2), an important area in subtropical China hosting the Three Gorges Reservoir Area. We observed significant increases in summer forest fires under anomalous dry-hot summer conditions, where total burned area was 3-6 higher than the historical annual mean (largely confined to the winter season). Vapor pressure deficit, an indicator of hot and dry conditions, was a strong predictor of fire activity, with major wildfires occurring on days where VPD was higher than 3.5kPa. Results indicate that major wildfire activity may occur in the area as a result of climate change, unless strong fire prevention policies are implemented.