Sediment incipience under flows passing a backward-facing step was studied. A series of experiments were conducted to measure scouring depth, probability of sediment incipience, and instantaneous flow velocity field d...Sediment incipience under flows passing a backward-facing step was studied. A series of experiments were conducted to measure scouring depth, probability of sediment incipience, and instantaneous flow velocity field downstream of a backward-facing step. Instantaneous flow velocity fields were measured by using Particle Image Velocimetry (PIV), and an image processing method for determining probability of sediment incipience was employed to analyze the experimental data. The experimental results showed that the probability of sediment incipience was the highest near the reattachment point, even though the near-wall instantaneous flow velocity and the Reynolds stress were both much higher further downstream of the backward-facing step. The possible me- chanisms are discussed for the sediment incipience near the reattachment point.展开更多
Serious desertification caused by human activity and climate change,in addition to water loss and soil erosion related to arsenic sandstone in the Mu Us Sandy Land,lead to severe scarcity of soil and water resources,w...Serious desertification caused by human activity and climate change,in addition to water loss and soil erosion related to arsenic sandstone in the Mu Us Sandy Land,lead to severe scarcity of soil and water resources,which causes worse local agricultural conditions accordingly.Many physical properties of arsenic sandstone is complementary with that of sand,arsenic sandstone is therefore supposed to be blended to enhance water productivity and arability of sandy land.Container experiments are carried out to study the enhancement of water holding capacity of the mixture,the blending ratio of arsenic sandstone and sand,and the proper size of the arsenic sandstone particles,respectively.The results of the experiments show that particle size of 4 cm with a ratio of 1∶2 between arsenic sandstone and sand are the proper parameters on blending.Both water content and fertility increase after blending.Water use efficiency in the mixture is 2.7 times higher than that in sand by the water release curves from experiments.Therefore,a new sand control and development model,including arsenic sandstone blending with sand,efficient water irrigation management and reasonable farming system,is put forward to control and develop sandy land so that water-saving agriculture could be developed.Demonstration of potato planting about 153.1 ha in area in the Mu Us Sandy Land in China indicates that water consumption is 3018 m3/ha in the whole growth period.It means that about 61%of irrigation water can be saved compared with water use in coarse sand without treatment.Recycle economic mode and positive feedback of sand resource-crop planting-soil resource are constructed,which changes sand into arable soil and make it possible to develop water-saving agriculture on it.The proposed model will be helpful for soil-water resources utilization and management in the Mu Us Sandy Land.展开更多
In the present study, we aimed to prepare poloxamer 403/407 mixed micelles in order to improve the solubility and oral bioavailability of genistein. Genistein was incorporated in the mixed poloxamer micelles by thin-f...In the present study, we aimed to prepare poloxamer 403/407 mixed micelles in order to improve the solubility and oral bioavailability of genistein. Genistein was incorporated in the mixed poloxamer micelles by thin-film hydration method, and its physicochemical properties, including particle size, zeta potential, entrapment efficiency and drug loading, were investigated. In vitro release of genistein from the mixed micelles was monitored by dialysis method, and pharmacokinetic study of genistein loaded mixed micelles was carried out in rats. We found that the particle size and zeta potential of mixed micelles were（20.31±0.43） nm and（–8.94±0.35） m V, with encapsulation efficiency 90.59%±0.67% and drug loading 7.74%±0.05%. Solubility of genistein in mixed micelles reached 3.80 mg/m L, which was about 130 times higher than that in water. Genistein-loaded mixed micelles showed sustained release characteristics in vitro with no burst release phenomenon, but it was faster than suspension. The AUC0–t and AUC0–∞ of mixed micelles were 196.74% and 204.62% greater than that of genisein suspension, respectively. Consequently, poloxamer 403/407 mixed micelles significantly improved the solubility and oral bioavailability of genistein, which could be used as an effective drug delivery system for oral administration of poorly soluble drugs.展开更多
基金National Natural Science Foundation of China (No.10602017)Maritime Research Center and DHI-NTU Center of Nanyang Technological University, Singapore
文摘Sediment incipience under flows passing a backward-facing step was studied. A series of experiments were conducted to measure scouring depth, probability of sediment incipience, and instantaneous flow velocity field downstream of a backward-facing step. Instantaneous flow velocity fields were measured by using Particle Image Velocimetry (PIV), and an image processing method for determining probability of sediment incipience was employed to analyze the experimental data. The experimental results showed that the probability of sediment incipience was the highest near the reattachment point, even though the near-wall instantaneous flow velocity and the Reynolds stress were both much higher further downstream of the backward-facing step. The possible me- chanisms are discussed for the sediment incipience near the reattachment point.
基金Under the auspices of National Natural Science Foundation of China(No.51079120)Education Department Research Program of Shaanxi Province(No.12JK0481)Water Conservancy Science and Technology Plan of Shaanxi Province(No.2012-07)
文摘Serious desertification caused by human activity and climate change,in addition to water loss and soil erosion related to arsenic sandstone in the Mu Us Sandy Land,lead to severe scarcity of soil and water resources,which causes worse local agricultural conditions accordingly.Many physical properties of arsenic sandstone is complementary with that of sand,arsenic sandstone is therefore supposed to be blended to enhance water productivity and arability of sandy land.Container experiments are carried out to study the enhancement of water holding capacity of the mixture,the blending ratio of arsenic sandstone and sand,and the proper size of the arsenic sandstone particles,respectively.The results of the experiments show that particle size of 4 cm with a ratio of 1∶2 between arsenic sandstone and sand are the proper parameters on blending.Both water content and fertility increase after blending.Water use efficiency in the mixture is 2.7 times higher than that in sand by the water release curves from experiments.Therefore,a new sand control and development model,including arsenic sandstone blending with sand,efficient water irrigation management and reasonable farming system,is put forward to control and develop sandy land so that water-saving agriculture could be developed.Demonstration of potato planting about 153.1 ha in area in the Mu Us Sandy Land in China indicates that water consumption is 3018 m3/ha in the whole growth period.It means that about 61%of irrigation water can be saved compared with water use in coarse sand without treatment.Recycle economic mode and positive feedback of sand resource-crop planting-soil resource are constructed,which changes sand into arable soil and make it possible to develop water-saving agriculture on it.The proposed model will be helpful for soil-water resources utilization and management in the Mu Us Sandy Land.
基金The Zhejiang Public Welfare Technology Application Research Project(Grant No.2015C31100)the Ningbo Science and Technology Innovation Team Project(Grant No.2015C110027)
文摘In the present study, we aimed to prepare poloxamer 403/407 mixed micelles in order to improve the solubility and oral bioavailability of genistein. Genistein was incorporated in the mixed poloxamer micelles by thin-film hydration method, and its physicochemical properties, including particle size, zeta potential, entrapment efficiency and drug loading, were investigated. In vitro release of genistein from the mixed micelles was monitored by dialysis method, and pharmacokinetic study of genistein loaded mixed micelles was carried out in rats. We found that the particle size and zeta potential of mixed micelles were（20.31±0.43） nm and（–8.94±0.35） m V, with encapsulation efficiency 90.59%±0.67% and drug loading 7.74%±0.05%. Solubility of genistein in mixed micelles reached 3.80 mg/m L, which was about 130 times higher than that in water. Genistein-loaded mixed micelles showed sustained release characteristics in vitro with no burst release phenomenon, but it was faster than suspension. The AUC0–t and AUC0–∞ of mixed micelles were 196.74% and 204.62% greater than that of genisein suspension, respectively. Consequently, poloxamer 403/407 mixed micelles significantly improved the solubility and oral bioavailability of genistein, which could be used as an effective drug delivery system for oral administration of poorly soluble drugs.
