One-pot achievement of ethyl levulinate from cassava was conducted in ethanol–water system over several simple sulfate salt catalysts. Al2(SO4)3catalyst had the best performance in synthesizing ethyl levulinate compa...One-pot achievement of ethyl levulinate from cassava was conducted in ethanol–water system over several simple sulfate salt catalysts. Al2(SO4)3catalyst had the best performance in synthesizing ethyl levulinate comparing with those of a series of sulfate salts. The highest yields of ethyl levulinate was up to 39.27% as well as 7.78% levulinate acid when cassava was catalyzed in ethanol medium by adding 10?wt% water.13C and1H NMR spectroscopic investigations confirmed that isomerization of glucose to fructose over Al2(SO4)3catalyst is an important step in producing ethyl levulinate and levulinate acid. Due to aggregations of Al3+under hydrothermal conditions, tiny amount of Al3+were detected in filtrate at the percentage of 0.32% even if in absolute water. Br?nsted and Lewis acids could improve the yield of ethyl levulinate and levulinate acid by synergistic effect. All results suggested that Al2(SO4)3was a simple and efficient catalyst for ethyl levulinate and levulinate acid production. ? 2016 Science Press展开更多
The canopy stomatal movement, a plant physiological process, generally occurs within leaves but its influence on exchange of CO2, water vapor, and sensible heat fluxes between atmosphere and terrestrial ecosystem. Man...The canopy stomatal movement, a plant physiological process, generally occurs within leaves but its influence on exchange of CO2, water vapor, and sensible heat fluxes between atmosphere and terrestrial ecosystem. Many studies have documented that the interaction between leaf photosynthesis and canopy stomatal conductance is obvious. Thus, information on stomatal conductance is valuable in climate and ecosystem models. In current study, a newly developed model was adopted to calculate canopy stomatal conductance of winter wheat in Huang-Huai-Hai (H-H-H) Plain of China (31.5 - 42.7°N, 110.0 - 123.0°E). The remote sensing information from NOAA-AVHRR and meteorological observed data were used to estimate regional scale stomatal conductance distribution. Canopy stomatal conductance distribution pattern of winter wheat on March 18, 1997 was also presented. The developed canopy stomatal conductance model might be used to estimate canopy stomatal conductance in land surface schemes and seems can be acted as a boundary condition in regional climatic model runs.展开更多
Response pattern was investigated for seedlings of Salix psammophila, a dominant shrub in Maowusu sandland, to the simulated precipitation change by artificially controlling water supply at four levels. The growth cha...Response pattern was investigated for seedlings of Salix psammophila, a dominant shrub in Maowusu sandland, to the simulated precipitation change by artificially controlling water supply at four levels. The growth characters, in terms of plant height, stem diameter, total branch number, total leaf number and area, total bifurcation ratio, total branch lenght and branch number, branch lenght, leaf number and leaf area of each branch order, and leaf, branch and root biomass significantly increased when water supply increased. That water supply had significant effect on biomass allocation showed different investment pattern of biomass resource of the seedlings grown under different water supply treatments. Stomatal density of abaxial leaf surface decreased, and stomatal apparatus length and width of adaxial and abaxial leaf surface increased with the increase of water supply, while Stomatal density of adaxial leaf surface was not affected by water supply. Water supply obviously affected the diumal changes of photosynthetic rate, and the photosynthetic rate of the seedlings showed strongly midday depression grown under the 157.5 mm water supply, but not grown under higher water supply. Additionally the assimilation-light response curves and flourescence efficiency more showed that water supply improve photosynthesis capacity. Finally, S. psammophila seedlings stood out by their slow growth and relatively high investments in root growth in order to reduce tissue losing rate and consumption of water resource for keeping water balance under water stress. The seedlings that grown under rich water supply did by their fast growth and relatively high investments in branch and leaf growth in order to improve the power of capturing light energy for higher photosynthesis.展开更多
The application of atrazine in China during the last ten years has led to some environmental problems. In this paper, the multimedia model of atrazine in soil-plant-groundwater system at Baiyangdian Lake area in North...The application of atrazine in China during the last ten years has led to some environmental problems. In this paper, the multimedia model of atrazine in soil-plant-groundwater system at Baiyangdian Lake area in Northern China was established using a fugacity approach, and verified with observed values. The model involved 7 environmental compartments which are air, groundwater, soil, corn roots, corn stem, corn leaf and kernel of corn. The results showed that the relative errors between calculated and observed values have a mean value of 24.7%, the highest value is 48% and the lowest value is 1.4%. All these values indicated that this multimedia model can be used to simulate the environmental fate of atrazine. Both the calculated and observed values of concentrations of atrazine in plant compartments are in the following order: in corn roots > in corn stem > in kernel of corn > in corn leaf, it exhibited a good regularity. The prediction results indicated that concentrations of atrazine in the groundwater and kernel of corn will override the limitation of 3 μg/L and 0.05 mg/kg respectively.展开更多
A two-dimensional （2D） optimized nanotaper mode converter is presented and analyzed using the finite- difference time-domain （FDTD） method. It can convert the mode size in a silicon pillar waveguide （PWG） from 4...A two-dimensional （2D） optimized nanotaper mode converter is presented and analyzed using the finite- difference time-domain （FDTD） method. It can convert the mode size in a silicon pillar waveguide （PWG） from 4 μm to 1 μm over a length of 7 μm and achieve a transmission efficiency of 83.6% at a wavelength of 1.55 μm. The dual directional mode conversion of the nanotaper and its ability to perform mode compression and expansion are also demonstrated. The broadband with high transmittance is satisfied in this structure. Using this silicon-based nanotaper, mode conversion between integrated photonic devices can be more compact and efficient.展开更多
基金supported by the National Natural Science Foundation of China(51536009 and 51576199)
文摘One-pot achievement of ethyl levulinate from cassava was conducted in ethanol–water system over several simple sulfate salt catalysts. Al2(SO4)3catalyst had the best performance in synthesizing ethyl levulinate comparing with those of a series of sulfate salts. The highest yields of ethyl levulinate was up to 39.27% as well as 7.78% levulinate acid when cassava was catalyzed in ethanol medium by adding 10?wt% water.13C and1H NMR spectroscopic investigations confirmed that isomerization of glucose to fructose over Al2(SO4)3catalyst is an important step in producing ethyl levulinate and levulinate acid. Due to aggregations of Al3+under hydrothermal conditions, tiny amount of Al3+were detected in filtrate at the percentage of 0.32% even if in absolute water. Br?nsted and Lewis acids could improve the yield of ethyl levulinate and levulinate acid by synergistic effect. All results suggested that Al2(SO4)3was a simple and efficient catalyst for ethyl levulinate and levulinate acid production. ? 2016 Science Press
文摘The canopy stomatal movement, a plant physiological process, generally occurs within leaves but its influence on exchange of CO2, water vapor, and sensible heat fluxes between atmosphere and terrestrial ecosystem. Many studies have documented that the interaction between leaf photosynthesis and canopy stomatal conductance is obvious. Thus, information on stomatal conductance is valuable in climate and ecosystem models. In current study, a newly developed model was adopted to calculate canopy stomatal conductance of winter wheat in Huang-Huai-Hai (H-H-H) Plain of China (31.5 - 42.7°N, 110.0 - 123.0°E). The remote sensing information from NOAA-AVHRR and meteorological observed data were used to estimate regional scale stomatal conductance distribution. Canopy stomatal conductance distribution pattern of winter wheat on March 18, 1997 was also presented. The developed canopy stomatal conductance model might be used to estimate canopy stomatal conductance in land surface schemes and seems can be acted as a boundary condition in regional climatic model runs.
文摘Response pattern was investigated for seedlings of Salix psammophila, a dominant shrub in Maowusu sandland, to the simulated precipitation change by artificially controlling water supply at four levels. The growth characters, in terms of plant height, stem diameter, total branch number, total leaf number and area, total bifurcation ratio, total branch lenght and branch number, branch lenght, leaf number and leaf area of each branch order, and leaf, branch and root biomass significantly increased when water supply increased. That water supply had significant effect on biomass allocation showed different investment pattern of biomass resource of the seedlings grown under different water supply treatments. Stomatal density of abaxial leaf surface decreased, and stomatal apparatus length and width of adaxial and abaxial leaf surface increased with the increase of water supply, while Stomatal density of adaxial leaf surface was not affected by water supply. Water supply obviously affected the diumal changes of photosynthetic rate, and the photosynthetic rate of the seedlings showed strongly midday depression grown under the 157.5 mm water supply, but not grown under higher water supply. Additionally the assimilation-light response curves and flourescence efficiency more showed that water supply improve photosynthesis capacity. Finally, S. psammophila seedlings stood out by their slow growth and relatively high investments in root growth in order to reduce tissue losing rate and consumption of water resource for keeping water balance under water stress. The seedlings that grown under rich water supply did by their fast growth and relatively high investments in branch and leaf growth in order to improve the power of capturing light energy for higher photosynthesis.
基金TheNationalNaturalScienceFoundationofChina (No .2 97770 2 6 )andtheMajorProjectFoundationoftheChineseAcademyofSciences (KZ95 1
文摘The application of atrazine in China during the last ten years has led to some environmental problems. In this paper, the multimedia model of atrazine in soil-plant-groundwater system at Baiyangdian Lake area in Northern China was established using a fugacity approach, and verified with observed values. The model involved 7 environmental compartments which are air, groundwater, soil, corn roots, corn stem, corn leaf and kernel of corn. The results showed that the relative errors between calculated and observed values have a mean value of 24.7%, the highest value is 48% and the lowest value is 1.4%. All these values indicated that this multimedia model can be used to simulate the environmental fate of atrazine. Both the calculated and observed values of concentrations of atrazine in plant compartments are in the following order: in corn roots > in corn stem > in kernel of corn > in corn leaf, it exhibited a good regularity. The prediction results indicated that concentrations of atrazine in the groundwater and kernel of corn will override the limitation of 3 μg/L and 0.05 mg/kg respectively.
基金supported by the National Natural Science Foundation of China (Nos. 60578048 and 60706013)the National Basic Research Program of China (No. 2006CB708310)the Creative Foundation of Wuhan National Laboratory for Optoelectronics(No. P080003).
文摘A two-dimensional （2D） optimized nanotaper mode converter is presented and analyzed using the finite- difference time-domain （FDTD） method. It can convert the mode size in a silicon pillar waveguide （PWG） from 4 μm to 1 μm over a length of 7 μm and achieve a transmission efficiency of 83.6% at a wavelength of 1.55 μm. The dual directional mode conversion of the nanotaper and its ability to perform mode compression and expansion are also demonstrated. The broadband with high transmittance is satisfied in this structure. Using this silicon-based nanotaper, mode conversion between integrated photonic devices can be more compact and efficient.
