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Understanding the temporal and spatial dynamics of land use/cover (LUC) can contribute to reveal the impacts of climate change and human activities on ecosystems and thus be an important prerequisite for ecosystem management. As an ecologically vulnerable area in China, the Three Gorges Reservoir Area (TGRA) of the Yangtze River presented significant complexity in the response to environmental changes. However, there is a general lack of understanding in the underlying mechanism. In this study, we interpreted the time series remote sensing images derived from the Landsat sensors to map the LUC of the TGRA, and aimed to analyze the long-term changes in the distribution and structure of LUC and elucidate the evolution process of LUC, which could provide a scientific basis to understand the complexity of ecosystem changes and regional ecosystem management in ecologically fragile regions. The results showed that the TGRA presented the significant changes in spatial heterogeneity of LUC structure from 1990 to 2015. Meanwhile, the landscape changed from farmland to woodland (forest and shrubland). Farmland decreased from 66.2% to 40.4%, but woodland increased from 31.3% to 53.5%, buildings and water area increased gradually. Forest gradually spread to the middle of the TGRA, while the buildings presented a scattered expansion. In the altitude zone of 500-1000 m and slope zone of 15°-25°, woodland increased noticeably, and the coniferous forest, mixed forest and shrubland had a higher growth rate. In the study period, due to the urban construction and the various ecological restoration projects in the TGRA, the LUC structure varied with the dam ' s impoundment and was characterized by the ecosystem restoration. Ecological restoration projects were helpful to reduce the negative impacts of urban construction and economic development on the environment. [ABSTRACT FROM AUTHOR]

A new catalytic system was developed and applied to the involved in the synthesis of LLM-105, in which protonated peroxotungstate combining chitosan was used as catalyst. With H2O2 as oxidant, good to excellent yields could be achieved in the synthesis of pyrazine-1-oxide, 2,6-dimethoxypyrazine-1-oxide, 2,6-dichloropyrazine-1-oxide, and 2-chloro-6-methoxypyrazine-1-oxide without any addition of trifluoracetic acid, which provided a significant exploration toward novel and environmentally benign synthetic route for LLM-105. Theoretical studies were also carried out with Gaussian 03 to evaluate the oxidation process. All of the calculated data matched well with our experimental results. [ABSTRACT FROM AUTHOR]

The response of plant species composition, diversity and soil nutrient availability to different canopysizes and age gaps in a Pinus Massoniana plantation were surveyed in Taizishan, Hubei province, central China. The soil chemical properties of 27 gaps and 3 non-gaps were measured and compared. The study objectives were: (a) confirm whether and when nutrient pulses emerged in small gaps; (b) determine the effects of gap sizes and ages on the soil properties and species diversity in gaps; and (c) determine the response of species diversity to soil nutrient variables in gaps. The understory plants of all canopy gaps and non-gaps were identified. Diversity indices were employed in this study, and the relationship between understory plant diversity and soil chemical properties were analyzed by detrended canonical correspondence analysis (DCCA). The results showed that soil properties and species diversity were significantly impacted by forest gaps, and the effects of the gap ages were more extensive than those of the gap sizes. The nutrient pulses occurred in gaps, but the emergence of nutrient indicators pulses in different age and size gaps was different. [ABSTRACT FROM AUTHOR]

Molybdenum trioxide (MoO3) microrods, nanofibers, and nanoplates were synthesized via the hydrothermal method and high-temperature calcination method, respectively. Then the MoO3 was added into polyurethane elastomer, respectively. The flame retardancy and smoke suppression of the composites added with different MoO3 were studied by thermal gravimetric analysis, cone calorimeter, and smoke density. The results show that the three kinds of MoO3 with different morphologies could promote the formation of char and possess flame retardancy and smoke suppression, and MoO3 nanofibers exhibit a higher degree of flame retardancy, and 1 wt% addition could make the peak heat release rate of polyurethane elastomer composites reduce from 881.6 kW m−2 for a pure sample to 343.4 kW m−2, a decrease by 61.0%. As for smoke suppression, MoO3 nanoplates possess the best smoke suppression; 5 wt% could decrease a pure sample's smoke density by 41.3% from 361 to 212. Moreover, the char residue of composites after combustion was analyzed by Raman spectra and X-ray photoelectron spectroscopy, and the flame retardancy and smoke suppression mechanisms of MoO3 were discussed. [ABSTRACT FROM AUTHOR]