When the temperature of a thin layer of a solution is vertically controlled, Rayleigh-Bemard convection is observed. When a binary isobutyric acid aqueous solution is used as the binary mixture, phase separation is si...When the temperature of a thin layer of a solution is vertically controlled, Rayleigh-Bemard convection is observed. When a binary isobutyric acid aqueous solution is used as the binary mixture, phase separation is simultaneously induced at the approximate critical solution temperature. In this study, these behaviors of phase separation and convection were observed under microwave irradiation. When the microwave power was higher, coalescence of fine droplets after the initial phase separation was accelerated and the coalescence size decreased. However, the solution became more unsteady because of smaller interfacial tension or greater heat generated by the radiation. Finally, in cases of higher microwave power, a steady convection pattern could not exist for a prolonged period because the water-rich phase was more active toward microwave irradiation, and the vertical temperature gradient became disordered.展开更多
Alpine tundra ecosystems have specific vegetation and environmental conditions that may affect soil phosphorus （P） composition and phosphatase activities. However, these effects are poody understood. This study used...Alpine tundra ecosystems have specific vegetation and environmental conditions that may affect soil phosphorus （P） composition and phosphatase activities. However, these effects are poody understood. This study used NaOH-EDTA extraction and solution ^31P nuclear magnetic resonance （NMR） spectroscopy to determine soil P composition and phosphatase activities, including acid phosphomonoesterase （AcP）, phosphodiesterase （PD） and inorganic pyrophosphatase （IPP）, in the alpine tundra of the Changbai Mountains at seven different altitudinal gradients （i.e., 2000 m, 2100 m, 2200 m, 2300 m, 2400 m, 2500 m, and 2600 m）. The results show that total P （TP）, organic P （OP）, OP/TP, NaOH-EDTA extracted P and AcP, PD, and IPP activities over the altitude range of 2500-2600 m are significantly lower than those below 2400 m. The dominant extracted form of P is OP （73%0-83%） with a large proportion of monoesters （65%0-72%）, whereas inorganic P is present in lower proportions （17%-27%）. The activity of AcP is significantly positively correlated with the contents of soil OP, total carbon （TC）, total nitrogen （TN）, and TP （P 〈 0.05）, indicating that the AcP is a more sensitive index for responding P nutrient storage than PD and IPP. Soil properties, P composition, and phosphatase activities decrease with increased altitude and soil pH. Our results indicate that the distribution of soil P composition and phosphatase activities along altitude and AcP may play an important role in P hydrolysis as well as have the potential to be an indicator of soil quality.展开更多
Application of temperature gradient to a binary solution can work as a separation process like freezing desalination. Initial salinity is an important parameter on the final composition of the water obtained. In this ...Application of temperature gradient to a binary solution can work as a separation process like freezing desalination. Initial salinity is an important parameter on the final composition of the water obtained. In this paper, the authors study experimentally the effect of the concentration in aqueous solution on the double diffusion with phase change. NaCI-H20 solution at different salinity is frozen in a rectangular cavity to obtain ice becoming fresh water. Temperature, concentration and rate growth of the interface ice/brine are presented. Three concentrations are tested： 0.02%, 1% and 3.5%.展开更多
The work aims to develop a process for freezing desalination of seawater on cold walls. The experiments were performed with water/NaCl solutions of different concentrations and with samples of seawater. The pilot crys...The work aims to develop a process for freezing desalination of seawater on cold walls. The experiments were performed with water/NaCl solutions of different concentrations and with samples of seawater. The pilot crystallizer consists of a cooled tube immersed in a cylindrical double jacketed tank containing water to be treated. The complete process of desalination is conducted in two steps： the freezing step, leading to the crystallization of the ice layer and the sweating step, which consists of purifying the ice layer in depth by melting the impure zones. The systematic study of the influence of operating parameters has highlighted the important role of the cooling ramp and salinity of the solution on the purity of the ice produced. In the absence of stirring, the temperature of the double jacket also has a noticeable effect on the purity of the ice due to temperature gradients, and consequently, convection currents that may result in the solution. The results of this work show the feasibility of the technique and give a good indication of operating conditions that can be used to produce drinking water.展开更多
The author studies the L2 gradient flow of the Helfrich functional, which is a functional describing the shapes of human red blood cells. For any λi ≥ 0 and co, the author obtains a lower bound on the lifespan of th...The author studies the L2 gradient flow of the Helfrich functional, which is a functional describing the shapes of human red blood cells. For any λi ≥ 0 and co, the author obtains a lower bound on the lifespan of the smooth solution, which depends only on the concentration of curvature for the initial surface.展开更多
文摘When the temperature of a thin layer of a solution is vertically controlled, Rayleigh-Bemard convection is observed. When a binary isobutyric acid aqueous solution is used as the binary mixture, phase separation is simultaneously induced at the approximate critical solution temperature. In this study, these behaviors of phase separation and convection were observed under microwave irradiation. When the microwave power was higher, coalescence of fine droplets after the initial phase separation was accelerated and the coalescence size decreased. However, the solution became more unsteady because of smaller interfacial tension or greater heat generated by the radiation. Finally, in cases of higher microwave power, a steady convection pattern could not exist for a prolonged period because the water-rich phase was more active toward microwave irradiation, and the vertical temperature gradient became disordered.
基金National Natural Science Foundation of China(No.41171241)
文摘Alpine tundra ecosystems have specific vegetation and environmental conditions that may affect soil phosphorus （P） composition and phosphatase activities. However, these effects are poody understood. This study used NaOH-EDTA extraction and solution ^31P nuclear magnetic resonance （NMR） spectroscopy to determine soil P composition and phosphatase activities, including acid phosphomonoesterase （AcP）, phosphodiesterase （PD） and inorganic pyrophosphatase （IPP）, in the alpine tundra of the Changbai Mountains at seven different altitudinal gradients （i.e., 2000 m, 2100 m, 2200 m, 2300 m, 2400 m, 2500 m, and 2600 m）. The results show that total P （TP）, organic P （OP）, OP/TP, NaOH-EDTA extracted P and AcP, PD, and IPP activities over the altitude range of 2500-2600 m are significantly lower than those below 2400 m. The dominant extracted form of P is OP （73%0-83%） with a large proportion of monoesters （65%0-72%）, whereas inorganic P is present in lower proportions （17%-27%）. The activity of AcP is significantly positively correlated with the contents of soil OP, total carbon （TC）, total nitrogen （TN）, and TP （P 〈 0.05）, indicating that the AcP is a more sensitive index for responding P nutrient storage than PD and IPP. Soil properties, P composition, and phosphatase activities decrease with increased altitude and soil pH. Our results indicate that the distribution of soil P composition and phosphatase activities along altitude and AcP may play an important role in P hydrolysis as well as have the potential to be an indicator of soil quality.
文摘Application of temperature gradient to a binary solution can work as a separation process like freezing desalination. Initial salinity is an important parameter on the final composition of the water obtained. In this paper, the authors study experimentally the effect of the concentration in aqueous solution on the double diffusion with phase change. NaCI-H20 solution at different salinity is frozen in a rectangular cavity to obtain ice becoming fresh water. Temperature, concentration and rate growth of the interface ice/brine are presented. Three concentrations are tested： 0.02%, 1% and 3.5%.
文摘The work aims to develop a process for freezing desalination of seawater on cold walls. The experiments were performed with water/NaCl solutions of different concentrations and with samples of seawater. The pilot crystallizer consists of a cooled tube immersed in a cylindrical double jacketed tank containing water to be treated. The complete process of desalination is conducted in two steps： the freezing step, leading to the crystallization of the ice layer and the sweating step, which consists of purifying the ice layer in depth by melting the impure zones. The systematic study of the influence of operating parameters has highlighted the important role of the cooling ramp and salinity of the solution on the purity of the ice produced. In the absence of stirring, the temperature of the double jacket also has a noticeable effect on the purity of the ice due to temperature gradients, and consequently, convection currents that may result in the solution. The results of this work show the feasibility of the technique and give a good indication of operating conditions that can be used to produce drinking water.
基金Project supported by the National Natural Science Foundation of China(No.11026121)the TrainingProgramme Foundation for the Excellent Talents of Beijing(No.2012D005003000004)
文摘The author studies the L2 gradient flow of the Helfrich functional, which is a functional describing the shapes of human red blood cells. For any λi ≥ 0 and co, the author obtains a lower bound on the lifespan of the smooth solution, which depends only on the concentration of curvature for the initial surface.
