摘要 :
Land degradation and global warming are currently highly active research topics. Land degradation can both change land cover and surface climate and significantly influence atmospheric circulation. Researches have verified that ca...
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Land degradation and global warming are currently highly active research topics. Land degradation can both change land cover and surface climate and significantly influence atmospheric circulation. Researches have verified that carbon dioxide (CO_2) and methane (CH_4) are major greenhouse gases (CHG) in the atmosphere and are directly affected by human activity. However, to date, there is no research on the spatial distribution of GHG concentrations and also no research on how land degradations affect GHG concentrations in arid and semi-arid regions. In this study, we used GHG data from the ENVlronment SATellite (ENVISAT) and the Greenhouse gases Observing Satellite (GOSAT), the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) data from the MODerate resolution Imaging Spectroradiometer (MODIS) and precipitation data from ground stations to analyze the way land degradation affects GHG concentrations in northern China and Mongolia, which exhibit the most serious land degradation process in East Asia. Our research revealed that the CO_2 and CH_4 concentrations (XCO_2 and XCH_4) increased from 2003 to 2009 and then decreased into 2011. We used geostatistics to predict and simulate the spatial distribution of XCO_2 and XCH_4 and found that the distribution of XCO2 displays a seasonal trend and is primarily affected by plant photosynthesis, soil respiration and precipitation. As the distribution of XCH_4 is mainly affected by the sources' distribution, microbial processes, LST and submarine hydrate, the CH_4 concentration presents no obvious seasonal changes and the high XCH4 values are primarily found in northeast and southeast China. Land degradation increases the concentration of GHG: the correlation coefficient between NDVI and XCO_2 is R~2 = 0.76 (P < 0.01) and the value between NDVI and XCH_4 is R~2 = 0.75 (P < 0.01).
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摘要 :
Ions (C~+, N_2~+ and O~+) implantation into evaporated Ti films was performed in the transmission electron microscope (TEM). Ti films grown on NaCl (001) surfaces at room temperature consisted mainly of (0 3 · 5)-oriented hcp-Ti ...
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Ions (C~+, N_2~+ and O~+) implantation into evaporated Ti films was performed in the transmission electron microscope (TEM). Ti films grown on NaCl (001) surfaces at room temperature consisted mainly of (0 3 · 5)-oriented hcp-Ti and (110)-oriented CaF_2-type TiH_x. NaCl-type Ti compounds of (001)-oriented TiC_z, TiN_y and TiO_u were epitaxially formed by the transformation of (0 3 · 5)-oriented hcp-Ti to (001)-oriented fcc-Ti sublattices and the occupation of the octahedral (O-) sites by implanted ions, whereas (110)-oriented Ti compounds were formed from a (110)-oriented TiH_x without structural transformation of Ti sublattices. Observations of EELS elucidated that, in the early N-implanting stage, the variation of the energy of the loss peak due to plasmon excitation of the areas where TiH_x grew in the as-evaporated Ti films was different from that of the areas where hcp-Ti grew. Analysis of Mulliken bond overlap populations indicated that the occupation of O-sites by N atoms gives rise to weakening of Ti-Ti bonds and forming of Ti-N covalent bonds.
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摘要 :
Production of liquid fuels from biomass has drawn keen attention
in terms of petroleum alternatives and suppression of global warming
because biomass is renewable and carbon neutral. Fatty acid methyl
ester (FAME) is well-known as...
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Production of liquid fuels from biomass has drawn keen attention
in terms of petroleum alternatives and suppression of global warming
because biomass is renewable and carbon neutral. Fatty acid methyl
ester (FAME) is well-known as the first generation biodiesel, and is
produced through trans esterification of triglycerides from vegetable
oils and animal fats with methanol. Bio hydrofined diesel (BHD) is
another promising fuel, of which components are mainly aliphatic
hydrocarbons, and is produces by hydrogenation of triglycerides at
high pressure. However, these processes have some disadvantages
such as difficulty in the separation of oil, alkali catalyst, and
glycerin, and a high pressure operation with high cost.
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