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
The wettability of coarse-grained soils has been studied previously.However,soil drying in arid regions due to limited precipitation or irrigation has resulted in soil water repellency to some extent in fine-grained s...The wettability of coarse-grained soils has been studied previously.However,soil drying in arid regions due to limited precipitation or irrigation has resulted in soil water repellency to some extent in fine-grained soils.In this study,laboratory experiments were conducted to investigate the effects of plane(Platanus orientalis L.)leaf biochar with fine(<0.1 mm)and coarse grains(0.1-0.5 mm)on the wettability of a silty clay soil irrigated with saline and non-saline water.Eleven rates of each biochar,ranging from 0 to 10%with 1%intervals,were investigated along with five ionic strengths of water,including 0,0.2,0.4,0.6,and 0.8 mol L^(-1),prepared using sodium and calcium chloride,which are two dominant salts in arid regions.The results showed that application of 5%-10%fine-grained biochar changed the soil hydrophobicity class from strongly to slightly water-repellent,while only 4%coarse-grained biochar was sufficient for the same change in soil wettability.Furthermore,the use of 10%coarse-grained biochar made the soil hydrophilic.The positive effect of plane leaf biochar on soil water repellency reduction was limited by water salinity.The sodium chloride solution was more effective in decreasing the soil wettability than calcium chloride solution and increased the demand for biochar for soil water repellency reduction.In conclusion,plane leaf biochar could be beneficial in managing the hydrophobicity of fine-grained soils.However,water quality as well as biochar particle size determined the quantity of biochar required for improving soil wettability.展开更多
Water-repellent(WR) soil greatly influences infiltration behavior. This research determined the impacts of WR levels of silt loam soil layer during infiltration. Three column scenarios were utilized, including homogen...Water-repellent(WR) soil greatly influences infiltration behavior. This research determined the impacts of WR levels of silt loam soil layer during infiltration. Three column scenarios were utilized, including homogeneous wettable silt loam or sand, silt loam over sand(silt loam/sand), and sand over silt loam(sand/silt loam). A 5-cm thick silt loam soil layer was placed either at the soil surface or 5 cm below the soil surface. The silt loam soil used had been treated to produce different WR levels, wettable, slightly WR, strongly WR, and severely WR. As the WR level increased from wettable to severely WR, the cumulative infiltration decreased. Traditional wetting front-related equations did not adequately describe the infiltration rate and time relationships for layered WR soils. The Kostiakov equation provided a good fit for the first infiltration stage. Average infiltration rates for wettable, slightly WR, strongly WR, and severely WR during the 2 nd infiltration stage were 0.126, 0.021, 0.002, and 0.001 mm min^(-1) for the silt loam/sand scenario,respectively, and 0.112, 0.003, 0.002, and 0.000 5 mm min^(-1) for the sand/silt loam scenario, respectively. Pseudo-saturation phenomena occurred when visually examining the wetting fronts and from the apparent changes in water content(?θ_(AP)) at the slightly WR,strongly WR, and severely WR levels for the silt loam/sand scenario. Much larger ?θAPvalues indicated the possible existence of finger flow. Delayed water penetration into the surface soil for the strongly WR level in the silt loam/sand scenario suggested negative water heads with infiltration times longer than 10 min. The silt loam/sand soil layers produced sharp transition zones of water content. The WR level of the silt loam soil layer had greater effects on infiltration than the layer position in the column.展开更多
Two oil spills occurred in the Evrona Nature Reserve(southern Israel),in 1975 and 2014.This oil contamination induced highly persistent soil hydrophobicity.The objective of this study was to investigate the decrease i...Two oil spills occurred in the Evrona Nature Reserve(southern Israel),in 1975 and 2014.This oil contamination induced highly persistent soil hydrophobicity.The objective of this study was to investigate the decrease in oil-induced soil hydrophobicity under different environmental conditions and to assess the relationship between the hydrophobicity and hydrocarbon content.A laboratory incubation experiment was conducted over 1.5 years to monitor the soil hydrophobicity and total hydrocarbon concentration under different environmental conditions.We hypothesized that the addition of water(20% or 50% saturation),nutrients,and biosurfactants can accelerate the reduction in hydrophobicity and decomposition of hydrocarbons.Water drop penetration time and molarity of ethanol droplet tests were used to assess soil hydrophobicity.In parallel,alkane composition and total petroleum hydrocarbons were evaluated to indicate oil attenuation.The addition of water,nutrients,and biosurfactants resulted in a concomitant reduction in hydrophobicity and hydrocarbon concentration of varying degrees,exhibiting enhanced degradation and hydrophobicity reduction observed in treatments to which nutrients and biosurfactants were added.At the end of the incubation,however,soil hydrophobicity in all treatments remained severe,even though total petroleum hydrocarbon removal was fairly high and reached 40%–80%in the treatments to which water with or without nutrients and/or surfactants was added.展开更多
Objective: to explore the effect of nursing intervention in preventing umbilical infection of newborn. Methods: from January 2017 to July 2018, 112 newborns were selected as the research objects and randomly divided i...Objective: to explore the effect of nursing intervention in preventing umbilical infection of newborn. Methods: from January 2017 to July 2018, 112 newborns were selected as the research objects and randomly divided into the control group and the observation group, with 56 newborns in each group. The nursing care in the control group was relatively ordinary, while the nursing intervention was carried out in the observation group. Check the status of umbilical infection, periumbilical skin damage and umbilical cord shedding time in the two groups. Results: the incidence of umbilical infection and periumbilical skin lesions in the observation group were significantly less than those in the control group, and the duration of umbilical cord shedding was significantly less than that in the control group, the difference was statistically significant (P < 0.05). Conclusion: nursing intervention in the prevention of neonatal umbilical infection can effectively reduce the probability of umbilical infection, reduce skin lesions around the umbilicus, and reduce the drop time of umbilical cord.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The wettability of coarse-grained soils has been studied previously.However,soil drying in arid regions due to limited precipitation or irrigation has resulted in soil water repellency to some extent in fine-grained soils.In this study,laboratory experiments were conducted to investigate the effects of plane(Platanus orientalis L.)leaf biochar with fine(<0.1 mm)and coarse grains(0.1-0.5 mm)on the wettability of a silty clay soil irrigated with saline and non-saline water.Eleven rates of each biochar,ranging from 0 to 10%with 1%intervals,were investigated along with five ionic strengths of water,including 0,0.2,0.4,0.6,and 0.8 mol L^(-1),prepared using sodium and calcium chloride,which are two dominant salts in arid regions.The results showed that application of 5%-10%fine-grained biochar changed the soil hydrophobicity class from strongly to slightly water-repellent,while only 4%coarse-grained biochar was sufficient for the same change in soil wettability.Furthermore,the use of 10%coarse-grained biochar made the soil hydrophilic.The positive effect of plane leaf biochar on soil water repellency reduction was limited by water salinity.The sodium chloride solution was more effective in decreasing the soil wettability than calcium chloride solution and increased the demand for biochar for soil water repellency reduction.In conclusion,plane leaf biochar could be beneficial in managing the hydrophobicity of fine-grained soils.However,water quality as well as biochar particle size determined the quantity of biochar required for improving soil wettability.
基金supported by the National Natural Science Foundation of China (No. 51579213)the National Key Research and Development Program of China (No. 2017YFC0403303)
文摘Water-repellent(WR) soil greatly influences infiltration behavior. This research determined the impacts of WR levels of silt loam soil layer during infiltration. Three column scenarios were utilized, including homogeneous wettable silt loam or sand, silt loam over sand(silt loam/sand), and sand over silt loam(sand/silt loam). A 5-cm thick silt loam soil layer was placed either at the soil surface or 5 cm below the soil surface. The silt loam soil used had been treated to produce different WR levels, wettable, slightly WR, strongly WR, and severely WR. As the WR level increased from wettable to severely WR, the cumulative infiltration decreased. Traditional wetting front-related equations did not adequately describe the infiltration rate and time relationships for layered WR soils. The Kostiakov equation provided a good fit for the first infiltration stage. Average infiltration rates for wettable, slightly WR, strongly WR, and severely WR during the 2 nd infiltration stage were 0.126, 0.021, 0.002, and 0.001 mm min^(-1) for the silt loam/sand scenario,respectively, and 0.112, 0.003, 0.002, and 0.000 5 mm min^(-1) for the sand/silt loam scenario, respectively. Pseudo-saturation phenomena occurred when visually examining the wetting fronts and from the apparent changes in water content(?θ_(AP)) at the slightly WR,strongly WR, and severely WR levels for the silt loam/sand scenario. Much larger ?θAPvalues indicated the possible existence of finger flow. Delayed water penetration into the surface soil for the strongly WR level in the silt loam/sand scenario suggested negative water heads with infiltration times longer than 10 min. The silt loam/sand soil layers produced sharp transition zones of water content. The WR level of the silt loam soil layer had greater effects on infiltration than the layer position in the column.
基金funded by the Ministry of Environmental Protection of Israelfinancial support of the China Scholarship Council。
文摘Two oil spills occurred in the Evrona Nature Reserve(southern Israel),in 1975 and 2014.This oil contamination induced highly persistent soil hydrophobicity.The objective of this study was to investigate the decrease in oil-induced soil hydrophobicity under different environmental conditions and to assess the relationship between the hydrophobicity and hydrocarbon content.A laboratory incubation experiment was conducted over 1.5 years to monitor the soil hydrophobicity and total hydrocarbon concentration under different environmental conditions.We hypothesized that the addition of water(20% or 50% saturation),nutrients,and biosurfactants can accelerate the reduction in hydrophobicity and decomposition of hydrocarbons.Water drop penetration time and molarity of ethanol droplet tests were used to assess soil hydrophobicity.In parallel,alkane composition and total petroleum hydrocarbons were evaluated to indicate oil attenuation.The addition of water,nutrients,and biosurfactants resulted in a concomitant reduction in hydrophobicity and hydrocarbon concentration of varying degrees,exhibiting enhanced degradation and hydrophobicity reduction observed in treatments to which nutrients and biosurfactants were added.At the end of the incubation,however,soil hydrophobicity in all treatments remained severe,even though total petroleum hydrocarbon removal was fairly high and reached 40%–80%in the treatments to which water with or without nutrients and/or surfactants was added.
文摘Objective: to explore the effect of nursing intervention in preventing umbilical infection of newborn. Methods: from January 2017 to July 2018, 112 newborns were selected as the research objects and randomly divided into the control group and the observation group, with 56 newborns in each group. The nursing care in the control group was relatively ordinary, while the nursing intervention was carried out in the observation group. Check the status of umbilical infection, periumbilical skin damage and umbilical cord shedding time in the two groups. Results: the incidence of umbilical infection and periumbilical skin lesions in the observation group were significantly less than those in the control group, and the duration of umbilical cord shedding was significantly less than that in the control group, the difference was statistically significant (P < 0.05). Conclusion: nursing intervention in the prevention of neonatal umbilical infection can effectively reduce the probability of umbilical infection, reduce skin lesions around the umbilicus, and reduce the drop time of umbilical cord.
