The water drop penetration time(WDPT)test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores.It is used to evaluate the hydrophobicity of material...The water drop penetration time(WDPT)test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores.It is used to evaluate the hydrophobicity of materials.This study aims at investigating in more detail the soil-water interaction during the test,exposing its mechanism.For that,a model soil named Hamburg Sand was coated with a hydrophobic fluoropolymer and then a WDPT test was performed while computed tomography(CT)images were taken.Tomography experiments were performed at the P07 high-energy materials science(HEMS)beamline,operated by Helmholtz–Zentrum Hereon,at the storage ring PETRA III at the Deutsches Elektronen-Synchrotron(DESY)in Hamburg.Using synchrotron radiation,a tomogram can be obtained in about 10 min,way less time than regular laboratory X-ray sources usually owned by universities.The faster imaging enables the observation of the drop penetration during time and thus provides insight into the dynamics of the process.After that,digital discrete image correlation is performed to track the displacement of the grains throughout time.From the results one can observe that,as the drop is absorbed at the material's surface,the grains directly around the droplet base are dragged to the liquid-air interface around the drop,revealing grain kinematics during capillary interactions of the penetrating liquid and sand grains.展开更多
【目的】研究斥水性对不同类型植物种子发芽率的影响。【方法】以4种类型、共16种植物种子为试验材料,选用了4种WDPT(water drop penetration time,滴水穿透时间)分别为1、7、12、16 s的塿土土壤进行试验,研究了土壤斥水性对开始发芽时...【目的】研究斥水性对不同类型植物种子发芽率的影响。【方法】以4种类型、共16种植物种子为试验材料,选用了4种WDPT(water drop penetration time,滴水穿透时间)分别为1、7、12、16 s的塿土土壤进行试验,研究了土壤斥水性对开始发芽时间及种子发芽率的影响。【结果】(1)土壤斥水性对植物的开始发芽时间存在影响:花草类、作物类和蔬菜类植物种子的开始发芽时间随土壤斥水性的增强而延迟,树木类植物种子的开始发芽时间受土壤斥水性的影响规律不明显;(2)在试验的第20天,蔬菜类、花草类、树木类和作物类植物在亲水性土壤中的平均发芽率分别为30.00%、43.75%、15.00%和50.83%,均高于斥水性土壤中的发芽率,且WDPT越大发芽率越低。【结论】土壤斥水性对种子发芽率的影响效果在蔬菜类、花草类和作物类植物中比较明显,而树木类植物受土壤斥水性的影响不大。土壤斥水性对大部分植物都有影响,但对油松、油菜作用效果不明显。展开更多
基金funding of this research by the German Research Foundation(Deutsche Forschungsgemeinschaft,DFG)in the framework of Research Training Group GRK 2462:Processes in natural and technical Particle-Fluid-Systems at Hamburg University of Technology(TUHH).
文摘The water drop penetration time(WDPT)test consists of placing water drops on a material's surface in order to evaluate how long it takes to penetrate the pores.It is used to evaluate the hydrophobicity of materials.This study aims at investigating in more detail the soil-water interaction during the test,exposing its mechanism.For that,a model soil named Hamburg Sand was coated with a hydrophobic fluoropolymer and then a WDPT test was performed while computed tomography(CT)images were taken.Tomography experiments were performed at the P07 high-energy materials science(HEMS)beamline,operated by Helmholtz–Zentrum Hereon,at the storage ring PETRA III at the Deutsches Elektronen-Synchrotron(DESY)in Hamburg.Using synchrotron radiation,a tomogram can be obtained in about 10 min,way less time than regular laboratory X-ray sources usually owned by universities.The faster imaging enables the observation of the drop penetration during time and thus provides insight into the dynamics of the process.After that,digital discrete image correlation is performed to track the displacement of the grains throughout time.From the results one can observe that,as the drop is absorbed at the material's surface,the grains directly around the droplet base are dragged to the liquid-air interface around the drop,revealing grain kinematics during capillary interactions of the penetrating liquid and sand grains.
文摘【目的】研究斥水性对不同类型植物种子发芽率的影响。【方法】以4种类型、共16种植物种子为试验材料,选用了4种WDPT(water drop penetration time,滴水穿透时间)分别为1、7、12、16 s的塿土土壤进行试验,研究了土壤斥水性对开始发芽时间及种子发芽率的影响。【结果】(1)土壤斥水性对植物的开始发芽时间存在影响:花草类、作物类和蔬菜类植物种子的开始发芽时间随土壤斥水性的增强而延迟,树木类植物种子的开始发芽时间受土壤斥水性的影响规律不明显;(2)在试验的第20天,蔬菜类、花草类、树木类和作物类植物在亲水性土壤中的平均发芽率分别为30.00%、43.75%、15.00%和50.83%,均高于斥水性土壤中的发芽率,且WDPT越大发芽率越低。【结论】土壤斥水性对种子发芽率的影响效果在蔬菜类、花草类和作物类植物中比较明显,而树木类植物受土壤斥水性的影响不大。土壤斥水性对大部分植物都有影响,但对油松、油菜作用效果不明显。
