Spatial-temporal changes and driving forces of aeolian desertification of grassland in the Sanjiangyuan region from 1975 to 2015 based on the analysis of Landsat images.

The Sanjiangyuan region is the source of the Yangtze, Yellow, and Lantsang rivers and is an important water conservation area in China. Due to the high altitude and cold climate in the region, the vegetation ecosystem has become very sensitive to environmental changes. In recent decades, due to the impact of climate change and human activities, the grassland degradation and desertification in this region have become very serious. In order to study the changes in aeolian desertification of grassland (ADG) in Sanjiangyuan, the Landsat images and GIS technology were used to monitor the dynamics of ADG from 1975 to 2015, and the driving factors behind this were analyzed. The results revealed that from 1975 to 2000, the area of ADG increased by 2855.8 km2, and the growth rate was 114.23 km2 a-1. In contrast, the ADG was restored from 2000 to 2015, with a decrease of 1286.54 km2 and a rate of 85.77 km2 a-1. The main reasons for the expansion of ADG in the early stage were the rising temperature, the fluctuation of precipitation and wind speed, and the increase in intensified human activities. The main reasons for the reversal of ADG in the later stage were the warming and humidification of the climate, the reduction in wind speed, and the reduction in human activities and restoration of grassland caused by the ecological protection project.

Assessment of titanium metallization thin film deposited on alumina substrate: Microstructure and nano-indentation.

Surface titanium (Ti) metallization was conducted on alumina (Al2O3) through chemical vapor deposition (CVD) method derived from non-contact pack cementation. The effects of different deposition temperature (1000 °C, 1050 °C, and 1100 °C) were examined in this scenario. The morphology, phase composition, and interfacial defects of the resulting films were systematically investigated through scanning electron microscopy, energy dispersive spectrometry, and X-ray diffraction. The nanomechanical characterization of the proposed thin films was evaluated by conducting nano-indentation tests at different depths. The results revealed that uniform Ti films were coated on the Al2O3 substrate. During coating, the atoms on the matrix surface were driven to form different structure due to different deposition temperature, leading to disparate morphologies of the surface and the interface, which consequently influenced the binding force between the film and the substrate. Moreover, the nanomechanical properties were found to be related to the internal and interface structure. Decreased modulus and hardness were obtained for metallization films treated at 1050 °C, and plastic deformation was the main deformation pattern.